Docunlent Type] Specification
[Title of the Ti~ventiw~] BURRING METHOD AND BURRING APPARATUS
[Technical Field of the Invention]
[QOO I]
The present inventiorl relates to a burring method and a buning apparatus.
Priority is claimed on Japanese Patent Application No. 2014-014817, filed on
January 29,2014, the content of which is incorporated herein by reference,
[Related 4
[0002]
As is well knownj 'as a link structure member which connects a plurality of
objects to each othel; a link structure member in which a joining portion is formed on
an end por-tion oi* an intermediate position of a link structure member has been put into
practical use. For example, the Iink structure member is used in various applications
such as a link structure member for a construction structure, a link structure member
for a suspension of an automobile, or the like.
[0003]
For example, as the suspension device of an automobile, various types of
suspension devices have been put into practical use, and for example, in a fivelink
type suspension, suspensioll links such as a toiver link, an upper lit~ko, r a lateral Iiuk
are used (for example, refer to Patent Document 1 below).
[0004] .
In the link srructu~m~e mber, for exsr~nplea, suspension link dioivn in FIG 1
of Patent Document I irlcludes a joining portion 11 1 which is formed in a cylindlfcal
shape, and a joining portion 1 12 having wall portions which are formed in a U shape
andaredisposedsoas to facecachather. Thejoiningportions 311 and 112ai~
connected to each other by a rod portion 11 3. The joining portion 11 1 is co~u~ectetod
an axIe by fitthg and inserting a bush or lhe like into a hole and inserting a shaft
member or the like into the fitted and inselted bush. The joining portion 112 is
co~rnectedto a vehicle body by a bolt inserted into a fastening hole.
[0005]
For example, in tile suspension link, there is a lateral link in which a load
applied from the vehicle body to the IateraI link is not necessalaily Iarge and the lateral
Iitlk can be thinned. Howemr; in order to connect the joining portion to the rod
portion by welding, it may be necessary to thicken the thickness so as to obtain a
suficie~rts trength of a welded portion. As a result, there is a problem that the weight
of the link sttucu~m~e.m ber increases.
roooq
Meanwhile, in a case in which joining portions having wall portions which
face each other on end portions of metal pipes are integatty formed in order to
decrease the weight of the link structure member, the thickness of the joining portion is
set depending on the thickness of the forined metal pipe.
[0007]
As a result, it is necessary to stab1 jr hold a bush or the like within ranges of the
thicknesses of the facing ~vall~portioncos nfigul-ing the joinitrg portions, and stably
holding Qle bush or the like is not easy. Stably hdding the bush or the like is
significantly dificult in,cases in wlzich the diameter of the end portion of the metal
pipe increases, ihe thickness of the end portion is thiimed, and a busing holding portion
into which a hrge bush can be fitted and inserted is formed.
[0008]
Accordingly, in the joining portion including the bush holding portion, in
order to forin a rising wall portion on a periphcra1 edgc poi-tion such as a bus11 holdillg
llole formed 011 each of the facing wall portions, and, to increase a holding area in an
inner circumference of the bush holding hole, a bun-ing technology for forming a
burring shape portion in the bush l~oldingIm le or the like Is widely used (for example,
refer to Patent Documents 2 and 3). Hereinafter, as the bush holding hole or the like,
tlle,hole in which the rising wall portion is formed on the pel+ipllerael dge portion by
burring is wefemd to as a burring hole.
[Prior Art Document]
[Patent Document]
[0009J
patent Document l] Japanese Unexamined Patent Application, First
Publication No. 2007-076547
[Patent Document 21 Japanese Unexamined Patent Application, First
Publication No. 2005-246474
[Patent Doaunent 33 Japanese Unexan~inedP atent Apglicalbn, First
Publication No. 20 12-24768
[DiscIosure of the Invent ion]
[Problems to be Solved by the Invention]
. [oalo]
However, for example, in a case in which the burring apparatus disclosed in
Patent Document 2 is used, in order to forin the burring hole with respect to each of the
pair of wall portions facing each other, first, it is necessary to form one of the burring
hoks by burring one of the pair of wall portions, and thereafter, it is necessary to fmm
the otller buning hole by burring the otller one of the pair of wall portions.
Accordingly, it is necessary to perform the burring in two steps, and there is a problem
that thc work efficiency decrease,^.
[0011] .
In addition, as described above, in the case in which the pair of burring holes
is formed in two steps, since the n~isaligmenbt etween a center axis line of the burriling
hole foimed on one ~wlplo rtion and a center axis line of tlie burring hole formed on
the other wall portion easily occurs, it is dificult to form burr.iilg holes so as to have
the same axis line as the center axis lines with respect to the pair of wall pol-tioas.
[OO 1 21
Meanwhile, Patent Docurner~t3 discloses a technology which can
simultanmnsly form the burring holes having the same axis line with respect to the
pair of wall portions facing each other. However, in the techtlology disclosed in
Patent Document 3, before burring the pair of the walI portions, it is necessary to form
a prepared hole for burring with respect to each of the pair of wall portions using a
general punching device such as a punching machine (refer to Paragraph [0033] of
f atent Document 3).
[0013]
That is, irr the technology disclosed in Patent Docu~nent3 , first, after forming
the prepared hole with respect to each of the pair of wall portions using the general
punching device, it is necessary to burr the plepared hole using the burring apparatus.
Accordingly, the misalignnlent between the center axis line of the fillally obtained
burring hole,aild the center axis line of the prepared hole is likely tamcur.
[OO 141
If the misalignment between the center axis line of the burring hole and the
center axis line of the prepared hole occurs, burring hdes having shapes atld
dimensions different from design data are Tornled. As a result, for example, in R case
in which the burring hole is the bush holding hole of the lateral link, there is a concer~~
that attaclmlent accuracy of a bush and a bush hoIding force m y decrease.
In acldition, if the misaligmneilt behveen the center axis fine of the burring
hole and the center axis Iine of the prepared hole occurs, cracks easily occur in the
rising wall podon of the burring hole, and there is a concern that prod~~ctivimtya y
decrease.
[a01 51
The present invention is made in consideration of the above-described
cirwmstances, and an object thereof is to provide a burri~lgm ethod and a buwing
apparatus capable of accurately and effectively forming burring holes having the same
axis line as the center axis lines with respect to a first wall poltion and a second wall
pol-tion facing each other.
[Meam for Solving the Problem]
[0016j
In order to solve the above-described problems and achieve the related object,
the present invention adopts the following means.
(1) According to an aspect of the pi-esent invention, a burring method for
forming butling holes having a first axis line as center axis lines with respect to a first
wall portion and a second wall portion facing each other, includes: a first process of
disl~ositiga n intesna1 unit of a burring apparatus between the first wall portion and the
second WRU portion, disposing a first external unit of the burring apparatus outside the
first wail portion, and disposing a second external unit of the bulring apparatus outside
the second wall portion; a second process of, out of a piercing punch and a burring
punch which are shaft members having the first axis h e as the center axis lines
provided in at least one of the internal unit, the first extarnaI unit, and the second
exte~naul nit, and are pimvicled so as to be ~novablea long the first axis line, first,
forrnir~g prepared holes lmving the first axis lines as the center axis lines with respect
to the fii-st wall portion and the second wall portion using the piercing punch, and
thereafter, forming bul~i~hlogl es having the first axis line as the center axis lines with
respect to the first wall portion and the second walI portion using the burring punch;
and a third process of detaching the intexnal unit, the first external unit, and the second
external unit h m the first wall poltion and the second wall poltion.
[OO 171
(2) In the burring method according to (I), in the second process, after one
of the prepared holes is follned on the first wall portion using a first ppierciizg punch
provided in the first external unit, one of the burring holes may be formed by bending a
peripheral edge portion of the prepared hole of the first wall portion to the inside of the
first wall portion using a first burring punch which is provided in the first external unit
and has the first axis line as the center axis line along with the first piercing punch; and
after the other prepared hole is formed on the second wall portion using a second
piercing punch provided in the second externaI unit, the other burring hole may be
fornzed by bending a peripheral edge portion of the prepared hole of the second walI
portion to the inside of the second wall portion using a second burring punch which is
provided in- thesecond exfernal unit and has the first axis line as the center axis line
along with the second piercing punch.
C. [OO 1 81
(3) In the burring method according to (2), in the first process, among a first
burring l~alderw hich is provided in the first external unit and has a first though Imle
serving as a passage of the first burring punch, the first burring punch ~vhichis
disposed inside the first through hole, and the first piercing punch which is disposed
inside the first burring punch, the first burring holder and the first burring punch may
come into pressure contact with an outer wall surface of the first wall portion in a state
where center axis lines of the first through hole, the firsi piercing punch, and the first
bul-ring punch coincide with the first axis line; ainong a secor~db urring holder ~vllichis
provided in the second external unit a~cdh as a second through hole serving as a
passage of the second bttring punch, the second burri~lgp unch which is disposed
inside the second through hole, and the second piercing punch which is disposed inside
the second burring punch, the second burring holder and the second burring punch may
come into pressure contact with an outer wall surface of the second wall portion in a
state where center axis Iines of the second through hole, the second piercing punch,
and the second burring punch coincide with the first =is line; a first burring die which
is provided in the internal unit and has a first forming hole, and a first piercing die
which is provided inside the first forming hole arid has a first piercing hole may come
into pressure contact with an inner wall surface of the first wall portion in a state where
center axis lines of the first forming hole and the first piercing hole coincide with the
first axis line; and a second burring die which is provided in the internal unit and has a
second forming hole, and a second piercing die which is provided inside the second
forming hole and has a second piercing hole may cbme into pressure contact with an
inner wall surfice of the second wall porkion in a state where center axis Si~eos f the
second forming hole and the second piercing hob coincide with the first axis line.
.-. In the second process, one of the prepared holes inay be formed on the first
wall portion by moving the first piercing punch from the outside of the first wall
portion to the inside thereof atong the first axis line such that the first piercing punch is
inserted into the first piercing hole; the other prepared hole may be formed on the
second walt portion by moving the second piercing punch from the outside of the
second wall porti011 to the inside thereof along the first axis line st~chtl lat the second
piercing punch is inserted into the second piercing hole; the peripheral edge portion of
the prepared hole of the first wall portion may be bent to the inside of the first wall
portion to form one oft he burring holes by rnovj ng the first burring pu tic11 froin the
outside of the first wall portion to the inside thereof along the first axis line such that
the first burring punch is inserted into the first forming hole, and the first piercing die
may be returned to a position close to a center between tlie first wall pol-iion and the
second walI portion; the peripheral edge portion of the prepared hole of the second
wall poltion may be bent to the inside of the second wall portion to form the other
bul~ingh ole by moving the second bu14tlg punch from the outside oft he second wall.
portion to the inside thereof along the first axis line such that the second burring punch
is inserted into the second forming hole, and the second piercing die may be returned
to a position close to the center bebyeen the first wall portion and the second wall
portion; and the first burring die and the second burring die may be returned to the
position close to the center between the first wall pol-tiofi and the second wall. portion
after both of the burring holes are forllzed.
[OO 191
(4) In the burring method according to (3), in the first process, the first
burring die may come into pressure contact with tlie inner waf 1 surface oft lle first wall
portion and the second burring die may come into pressure contact with the inner wall
surface of the second ~valpl ortion by inselding w first stopper into a portion between
the first barring die and the seco~~budr ring die in the internal unit; and the first
piercing die may coine into p~cssurec ontact with the inner wall surface of the first wall
portion and the second piercing die may come into pressure contact wit11 the inner walI
surface of the second wall portion by inserting a secoi~dst opper into a portion between
the first piercing die and the second piercing die.
111 the second process, after the second stopper is removed from the portion
between the fixst piercing die and the second piercing die, one of the burring holes may
be formed on the first wall poi-tiori by inserting the first bui~ingp unch into the first
fonning hole, and the other burring hole may be formed on the second wall portion by
inserting the second burring punch into rhe second forming hole; and after both of the
burring holes are formed, the first stopper may be removed fiom the portion between
the first burring die and the second burring die, and the first burring die and the second
burring die {nay be retur~~etdo the position close to the center between the first wall
portion and the'secand wall portion by applying an external force to the first bu wing
die and the second bulTing die in a direction approaching each ofher.
(5) In the burring method accordiug to (I), in the second process, after one
of the prepared holes is formed on the fmt wal1 portion using a first piercing punch
provided in the first external unit, one of the burring holes may be formed by bending a
peripheral edge portion of the prepared hole of the first wall portion to the outside of
the first wall portion using a first burring punch which is provided in the internal unit
and has the fitst axis Iine as the center axis Iine alotlg with the fwst piercing punch; and
after the other prepared hole is formed on the second wall portion using a second
piercing punch provided in the second external unit, the other burring hole may be
formed by bending a per-lp11e1d edgeportion of the prepared hole of the second wall LL
poition to the outside of the second wall portion rrsing a second burring punch which is
provided in the interrlal unit and has the first axis line as the center axis line along with
the second piercing p~~nch.
(6) 111 the burring nlcthod acceding to (5), in the first process, among a first
burring die which is provided in the first external unit and has a first forming hole, a
first piercing h~oIdetw hich is provided inside the first forming llole and has a first
through hole sewing as a passage of the first piercing punch, and the first piercing
punch which is provided inside the first through hole, the first bul-ring die and the first
piercing holder may come into pressure contact with an outer wall sutfiice of the first
wall poition in a state where center axis lines of the fuxt forn~ingh ole, the first through
hole, and the first piercing punch coincide with the first axis line; among a second
burring die which is provided in the second external unit and has a second forming
hole, a second piercing holder which is provided inside the second forming hoIe and
has a second through hole serving as a passage of the second piercing punch, and tlie
second piercing punch which is pi-ovided inside the second through hole, the second
burring die and the second piercing holder may come into pressure contact with an
outer wall surface of the second wall portion in a state where center axis lines of the
second forming hole, the second through hole, and the second piercing punch coincide
with the first axis line; and after a tubular housing which is provided in the internal unit,
i~lcludesth e first burring putlcfi and the second burring punch, and has both opened
ends is disposed between the fist wall portion and the second wall portion in a state
where center axislines of the first bur~ingp unch, the second burring pu~lcha, nd the
housing coiiicide with the first axis line, the first burring punch may come into
pressure contact with an inner .wall surface of the first wall portion, and the second ., ,
burring punch may come into pressure contact with an inner wall surface of the second
~ ~por1tion1.
In the second process, one of the prepared holes may be formed on the first
wall pol-tion by moving die first piercing punch from the outside of the first wall
- 10 -
portion to the inside thereof along the first axis line such that the first piercing punch is
inserted into the first piercing hole provided in the first buring punch; the othex
prepared 11ole may be formed on the second wall portion by moving the second
piercing punch from the outside of the second wall portion to the inside thereof along
the first axis line such that the second pie~ingpunch.iisn serted into the second
piercing hole provided in the first burring punch; the peripheral edge portion of the
prepared hole of the first wall portion may be bent to the outside of the first .r+all
portion to form one of the burring holes by moving the first burring punch fivm the
inside of the fist wall poition to the outside thereof along the first axis line such that
the first burring punch is inserted inb the first forming hole; the peripheral edge
poriion of the prepared hole of the second wall portion may be bent to the outside of
the second wall poi-iion to form the other bul~ingh ole by moving the second burring
punch from the inside of tl~ese cond wall poi-tion to the outside thereof along the first
axis Ijne such that the second burring punch is inserted into the second forming hole;
and the first burring punch arld the second burring punch may be returned to-the
position close to the ccnter between the first wall portion and the second wall portion
after both of the burring holes are formed.
COO221
- (7) In tlie,b~u~~minegth od according to (61, in the first process, the first
burring punch may co~nein to pressure contact wit 11 the inner wall surface of the first
wall portion and the secand burring pmlch may come into pressure contact witb.the
inner wall surface of the second u~alpl ortion by inserting a stopper into a portion
between the first burring punch and the second burring punch in tlie internal unit.
In the second process, the first burring punch may move fium tlze inside of the
first wall portion to the outside thereof along the first axis line to form one of the
burring holes on the first wall portion and the second burring punch may move from
the inside of the,secqnd wall portion to the outside thereof along the first axis Iif>e to
form the other burring hole on the second waIl portion by inserting the stopper deeper
into the poltion between the first burring punch and the secor~db urring puach; and
after both of the burring holes are fornled, the stopper may be removed ftom the
po~qionb etween the first burring punch and the second burring pt~ncha, nd the first
burring die and the second burring die may be returned to the position cIose to the
center between the first wall portion and the second wall portiol~b y applying an
extel-11a1fo rce to the first burring die and the second bur.1-ingd ie in a direction
approaching each other.
[0023]
(8) In the burring method according to (6), in the first process, the first
burring pundl may come into pressure contact with tile inner wall surface of the first
wall portion and the secorld bul~ingp unch may come into pressure contact with the
inner wall surface of the second wall portion by inserting a stopper into a portion
between the first burring punch and the second burring punch in the internal unit.
In the second process, after the prepared hole is formed on each of the first
wall portion and the second wall portion using the first piercing punch and the second
piercing punch, by moving the second piercing punch toward the first waIl portion
along the first axis line in a state where a front end of the second piercing punch comes
into contact with a-bottom portion of the second piercing hole of the second bu~~ing
putich, the second bulri~lgp unch, a separable separatiorl block provided ia the stopgel;
and the first burring punch may simuItaneous1y move toward the outside of the first
wall poriion along the first axis line to form one of the burring holes OII the first rvali
portion; by moving the first piezciilg punch toward the second wall portion along the
first axis line in a state where a front end of the first piercing punch comes into contact
wilh a bottom portion of the first piercing hole,of tile first burring punch, the first
burring pimch, the separation block provided in the stopper, and the second burring
. plmch may sjmultaneously move toward file outside of the second wall portion along
the first axis line to f o ~tnhe other burring hole on the second wall portion; and by
moving the second piercing punch toward the first wall portion along the first axis line
in a state where the ffont end of the second piercing punch comes into contact with the
bottom portion of the second piercing hole of the second burring punch, the separation
block rnay be retunled into the stopper.
[OD241
(9) In the burring method according to (1.1, in the second process, after one
of the ptepatd holes is formed on the first wall portion using a first piercing punch
provided in the fint external unit, one of thc burring holes may be formed by bending a
peripheral edge portion of the prepared hole of the fiixt wall portion to the inside of the
first wall portion using a first bu~~inpugn ch which is provided in the first external unit
and has the first axis Iine as the center axis line along with the first piercing punch; and
after the other prepared hole is formed on the sccond svaIl portioil using a second
piercing punch provided in the internal unit, the other burring hole may be formed by
bending a peripheral edge portion of the pi-epar-ed lloie of the second lvall portion to the
outside of the second wall portion using a second burring punch which is provided in
the internaltunit and has fhe first axis line as the center axis Iine along with the second
piercing punch.
[0025j
(10) In the burring method according to (91, in the first process, among a
first burring holder wkicll is provided in the first external unit arid has a first through
hole se~vinga s a passage of the first blli~ingp unch, the first burring punch ~vhichis
disposed inside the first through hole, and the first piercing pmch which is attached to
a front end of the first burlhifigp unch, the first burring holder may came into pressure
contact with an outer wall surface of the first wail portion in a state where cerlter axis
lines of the first through hole, the first butring punch, and the first piercing punch
coincide with the first axis line; a first burring die which is provided in the internal unit
and has a fit-st folming hole, and a &st piercing die which is provided inside the first
forming hole and has a first piercing hole may come into pressure contact with an inner
wall surface of the firsst !will portion in a state where center axis lines of the first
forming hok and the first piercing hole coincide with the first axis line; among a
second burring holder whicll is provided in the internal unit and has a second through
hole serving as a passage oft he second burring punch, the second burring punch which
is disposed inside the second through hole, and the second pie~cingp unch which is
aitacl~edto a front end of the second burring punch, the second burring holder may
come illto pressur- contact with an inner wall surface of the second wail portion in a
state where ceilier axis lines of the second through hole, the second burring punch, and
the second piercing punch coi~~cidweit h the first axis line; and a second burring die
which is provided in the second external unit and has a second forming hole, and a
second piercing die whicll is provided inside the second forming hole and has a second
piercing hole may come into pressure contact with an outer \vat1 surface of the second
wall'prtion in a state where center axis lines of the secold forming hole and the
second piercing hole coincide with the first axis line.
111 the second process, one of the prepared holes may be fonned on tile first
wall portion by moving the first burring punch and the first piercing punch from the
outside of the fit-st wall portion to the inside thereof along the first axis Ijne such that
the first piercing pu~~icsh in serted illto the first piel-cirlgh ole; by moving the first
burring punch fivn~th e ontside,,ofth e first wall portion to tfie inside thereof along the
first axis line such that the first burring punch is inserted into the first forming hole
after the piepared hole is formed on the first wall poltion, the peripheral edge portion
of the prepared hole of the fitst \wll portion may be bent to the inside of the first wall
poition to form one of the bwriag holes; by moving the first burring puncl~to ward the
second wall portion in a state where the front end of the fmt piercing punch comes into
contact with the bottom poltion of the first piercing hole, the second burring puncll and
the second piercing punch may move from the inside of the second wall portion to the
outside theleaf along the first axis line to form the other prepared hole on the seco~id
wall portion such that the second piercing yuilch is inserted into the second piercing
hole; by further movirlg the first but~jngp unch toward the second wall portion a k rt he
prepared hole is forrned on the second wall portion, the second burring punch may
move firom the inside of the sccond wall portion to the outside the~vofa long the first
axis line such that the second burring punch is inserted into the second forming hole,
and a peripheral edge of the prepared hole of the secorid wall portion may be bent to
the outside of the second wall portion to for1 the other burring hole; and by ~noving
the second burring punch to the inside of the second wall pol~iona fter the burring hole
is formed on the second wall poltion, tl~efi rst burring die and the first piercing die may
be rehlrned to a position close to tile center between the first wall partion and the
second wall port ion.
[0026]
(1 1) In the burring mnethod according to (101, in the first process,
insc~tinga stopper into a portion betwen the first burring holder and the second
burring die in the internal unit, the first burring die and the first piercing die disposed
inside tl~cfi rst burring die may come illto pressure contact with the irltier wall surface
of thc first wall portion, and the second burring holder and the second piefcillg punch
disposed inside the second burring holder nlay come illto pressure contact with the
inner wall surface of d~see cond wall portion.
In the second process, by moving the first burring punch toward the second
wail poition along tlze first axis line in a state where a front end of the first piercing
punch comes into contact with a bottom poltion of the first piercing hole of the first
piercing die, the first piercing die, a sepal-able separation block provided in the stopper,
and the second burring punch to which the second piercing punch is attached may
si~nultaneouslym ove toward the outside of the second wall poltion along the first axis
line, and after the burring hole of the first wall portion and the prepared hole of the
second wall portion are simultaneously formed, finally, the burring hole of the second
wall portion may be formed; after the separation block is returned into the stopper by
moving the first piercing die, the separation block, and the second bulring punch to the
- inside of the second wall portion, the stopper may be iemoved from the portion
behveen the first burring die and the second bu~~inhogld er; and the first bun-jng die
may be returned to the position close to the center between the first wall portion and
the seco~ldw all portion by applying an external force to the first burring die in a
direction toward the second wall portion.
[00271
(12) According to another aspect of the. pl-eserlt illvention, a b111ring
apparatus for fornling burring holes having a first axis line as cwlter axis lines with
respect to a first wall portion and a second wall portion king each other, includes; an
internal unit which is disposed between the first wall portion and the second wall
portion; a first external unit which is disposed outside the first waIl poriion; and a
second external unit which is disposed outside the second wall portion, in which at
least one of the internal unit, the first external urrit, and d ~see cond external unit
includes a piercing punch and a burri~igp uncl-1 which are shaft members having the
first axis line as the center axis lines and are provided so as to be movable along the
fi~*satx is line.
(13) In the burring apparatus according to (121, the first external unit may
include: a first piercing punch which hrms a pqaicd hole on the fust wall pol-tion;
and a first burring punch which has the first axis line as the center axis line along with
the first piercing punch, and bends a peripheral edge portion of the prepared hole of the
first wall portion to the inside of the first wall polqion to form the bunkg hole4
The second external unit may include: a second piercing punch which forms a
prepared hole on the second wall poltion; and a second burring punch which has the
first axis line as the center axis line along with the second piercing puncfl, and bends a
peripheral edge portion of the prepared hole of the second wall portion to the inside of
the secondwall portion to form the burring hole.
(14) In the burring apparatus according to (1 31, the first external. unit may
further include a first bur~ri~hlogl der which has a first through hole sewing as a passage
of the first burring punch and is provided so as lo be movable outside the first wail
poxtion in a state where a center axis line of the first tlvough hole coi~~cidwesit h the
firsst axis line.
The first busing punch may be provided so as to be n~ovabIeb etween the
outside and the inside of the finr wall portion along the first axis line in a state whc1.e a
center axis line of the first burring punch coincides with the first axis line inside the
first tlwough hole of the first burrir~gh older.
The first piercing pundi may be provided so as to be movable behueen the
outside and the inside of the first wall portion along the first axis line in a state where a
center axis Iine of the first piercing punch coincides with the first axis line inside the
first burring punch.
The second external unit may further include a secoi~db urring holder which
has w second through hole sewing as a passage of the second barring punch and is
provided so as to be movable outside the second wall portion in a state where a center
axis line of the second through hole coincides with the first axis line.
The second burring punch may be provided so as to be movable between the
outside and the inside of the second wall poition along the first axis line in a state
where a center axis line of the second burring punch coincides with the first axis line
inside the second through hole of the second burring holder,
The second piercing punch is piwvided so as to be movable between the
outside and the inside of the second wall portion along the first axis line in a state
where a center axis line of the second piercing punch coincides with the first axis Iine
inside the second burring punch.
The internal unit rnay include: a first burring die which has a first fonning
hole into wlich the fust burring punch is inselied, and is provided so as to be movable
inside the first wall poition along the first axis line In a state where a center axis line of
the first forning hole coir~cidews ith ,the first axis line; a first piercing die which has a .>
first piercing hole into which the first piercing punch is inserted, and is provided so as
to be tnovable inside the first walI portion along the fust axis line in a state where a
center axis line of the first pierci~lgh ole coincides with the first axis line inside the first
forming hole of the fust burring die; a second buming die which has a secorld forming
hole into which the second burl-ing punch is inserted, and is provided so as to be
movable inside the second walI portion along the first axis line in a state wlwe a center
axis line of the second forming llole coincides with the first axis line; and a second
piercing die which has a second piercing hole into which the second piercing punch is
inserted, and is provided so as to be movable hlside the second wall portion aIong the
first axis line in a state where a center axis line of the second piercing hole coincides
with the first axis line inside the second forming hole of the secoi~db urring die.
[0030]
(1 5) In the burring apparatus according to (1 4), in a case where a center
position between the first walI portion and the second wall portion on the first axis line
is defined as a reference point, the first burring die and the second burring die may be
disposed so as to face each other in a state where the reference point is interposed
therebetwen, and the first piercing die and the second piercing die may be disposed so
as to face each other in a state ~vhereth e reference point is interposed therebetween.
The internal unit may further include a fwst stopper and a second stopper
\vl~icfp~a ss through the reference point and are provided so as to be movable along a
second axis line oithogonal to the fi~sat xis Iine.
The first stopper may have w shape which causes the first burring die to ~nove
toward the fii-st wall portion and the second burring die to move toward the second
wall portion in a process in which the first stopper passes through the reference point
along the second axis line. .,,
The second stopper rnay have a shape which causes the first piercing die to
move toward the first wall portion and the second piercing die to move toward the
second wall portion in a proqess in which the second stopper passes through the
refclrlzce point along the second axis line.
COO3 1 j
( I 6) In the burring apparatus according to (1 51, the internal tinit may, further
irlclude a die reh~rnm echanism wl~ichs eparteiy applies an external fo1-cet oward the
reference point to each of the first bu~.ing die and the second burring die.
[0032]
(17) In the burring apparatus accol-ding to (12), the first external unit may
include a first piercing punch which forms a prepared hole on the first wall portion.
The second external ullit may i11cIude a second piercing punch which forms a
prepared hole on the second wall portion.
TIE internal unit may include: a &+st brvring punch which has the first axis
Iine as the center axis line along with the first piercing punch, and bends a peripheral
edge portion of the prepared hole of the fust wall portion to the outside of the frrst wall
portion to form the burring hole; and a second burring puncll which has the firsiaxis
line as the center axis line along with the second piercing punch, and bends a
peripheral edge portion of the prepared hole of the second wall portion to the outside
of the second wall portion to form the bul-ring hole.
[003 3 ]
(18) In the burring appa~.atuas ccording to (17), the first external unit may
further include: a first burring die whidi has tlle first forming hole into whicl~th e first
burring punch is inserted, and is provided so as to be movable along the first axis line
outside the first wall portion in a state where a center axis Iine of the first forming hale
coincides with the first axis line; and a first piercing llolder which has the first thty317gh
hde serving as a passage of the fii-st piercing punch and is provided so as to be
nzovable along the first axis line outside the first wall portion in a state w11ae a center
axis line of the first througli bole coincides will1 the fir31 axis line inside the first
+
forming hole of the first burring die.
The first piercing punch may be provided so as to be movable between the
outside and the inside of the first wall poltion along the first axis line inside the fil-st
through hole of the first piei-cing holder in a state where a center axis Ilne of the first
piercing puncll coincides with the first axis line.
. The second external unit may hrther include: a second bt~rringd ie which has
the second forming hole into which the second burring punch is i~lse~teadn,d is
provided so as to be movable along the first axis line outside the second wall poxtion in
a state where a center axis Iine of the second forming hole coincides wit11 the first axis
line; and a second piercing holder wllich has the second through hole serving as a
passage of the: second piercing punch and is prqvided so as to be movable along the
first axis line outside the second ~valpl ortion in a state where a center axis line of the
second through hole coincides wit11 the first axis Iine inside the second forming Role of
the second burring die.
The second piercing punch may be provided so as to be movable between the
outside and the inside of the second wall portion along the fust axis 1 ine inside the
second through hole of the second piercing holder in a state where a cenkr axis line of
the second piercing punch coincides with the first axis liae.
The internal unit-may further include a tubular llousing whicl~in cludes the
first burring punch atid the second burring prmc1-i and has both opened end surfaces, in
which the housing may be configured such that one end su~faceo f the 116using comes
into surface contact with an inner wall surface of the first wall portion and the other
end surface of the housing coines into surface contact with an inner waII surface of the
second wall portion.
Tile first burring punch may include a first piercing hole into whicl~th e first
piercing punch is inserted, arid is provided so as to be movable between the outside and
the insid. e .o. f the fitxt wall portion alo~lgth e first axis line inside the housing in a siate
where a center axis Iine of the first piercing hoIe coincides with the first axis line.
The second burring punch may include a second piercing hole into which the
second piercing punch is inserted, and is provided so as to be tnovabIe between the
outside and the inside of the second wall portion along the first axis line inside the
housing in a state where a center axis line of the second piercing hole coincides with
the first axis line.
[0034]
(19) In the burring apparatus accotding to (181, in a case where a center
position befiveen the first wall poition and the second wall portion an the first axis line
is defined as a reference point, the first burring punch and the second burring punch
may be disposed so as to face each other in a state where the reference point is
interposed therebehveen.
The internal unit may fi~iqherin clude a stopper ~vllichp asses through the
reference point and is provided st, as to be rnovabIe along a second axis line orthogonal
to the first axis line.
The stopper may have a shape which causes the first burring punch to move to
the outside of the first wall portion and the second burring punch to move to the
outside of the second wait portiotl in a process in which the stopper passes thl.ough the
1-efel.ence point-along the secorid axis line. *-.
I00351
(20) In the burring appat-atus acrsolAdingto (1 9 ), the internal uui t n~ayfu rther
include a burring punch return mechailism which separately applies an ex tcwal fo14ce
toward the reference point to each of the first bu~r.it~pgu nch and the second burring
(21) 111 the burring apparatus according fa (181, each of the first piercing
hole of the first burring punch and the second piercing hole of the second burring
p~mchm ay ii~cludea bottom portion.
In a case wl~el-ea center position between the first wall portion and the secolld
wall portion on the first axis line is defined as a reference point, the first burring punch
and the second burring punch may be disposed so as to face each other in a state where
the reference point is interposed therebetween, and the internal unit may further
indude a stopper which passes tlwough the reference point and is provided so as to be
rnovabie along a second axis line 01fhogonal to the first axis line.
The stopper may have a sllape which causes the first bwring punch to move
toward the fint wall portion and the second burring punch to move toward the second
wall portion in a process in which the stopper passes through the reference point along
the seco~ida xis Iirle.
The stopper nay itlclude a separation block which is separated from the
stopper when the stopper stops in a state where the first burring punch comes into
pressure contact with an inner wall surface of the first wal po~tioaln~d the secotld
bu~~inpugn ch comes into pressure contact with an irlller wall surface of the second
wall portion, and which is movable inside the liousing aIong the first axis line along
with the first burring punch and the second burring punch. ),.
[0037j
(22) ~n the burring apparatus according to (121, the first external unit may
include: a first piercing punch which fo~ma p repared hole on the first wall portion;
and a first burring punch which has the first axis line as the center axis line along with
the first piercing punch, and bends a peripheral edge portion of the prepared hole of the
first wall portion to the inside of the first walJ portion to form the burring hole.
The internal unit may include: a second piercing punch which fo~~ina s
plGepal.edh ole on the second wall portion; and a second burring punch which has the
first axis line as the center axis line along with the second piercing punch, and bends a
peripheral edge portion of the prepared hole of the second wall portion to the outside
of the second waIl poltion to form tlie baing hole.
[0038l
(23) In the burring apparatus according to (221, tlie first external unit may
further include a first burring holder which has a first through hde sewing as a passage
of the first burring punch and is provided so as to be movable outside the first waIL
poltion in a state where a center axis line of the first through hole coincides with the
first axis fine.
The first burring punch may be provided so as to be movable along the first
axis Iine inside the first though hole of the first burring holder in a state where a center
axis line of the first bulring coincides with the first axis line.
The first piercing punch may be attached to a front end of the first buning
punch while having the first axis Iine as the ce~ltera xis line along wit11 the fuxt bul-ring
punch.
The internal unit may fi~rtherin clude: a first burring die which has a first
,.formingh ole into which the first burring punch is inse~keda, nd is provided so as to be
rnovable along the first axis Iine jn a state where a center axis line of the first for~ning
hole coincides with the first axis line; a first piercing die which has a first piercing hole
into which the first piercing punch is inserted, and is piwvided so as to be movable
along the first axis line inside the frrst forming hole of the first burring die in a state
where a center axis Iinc of the first piercing hde coincides with the first axis line; and
a scctl~lrl burring llolder whicll has a second tlxough hole serving as a passage of the
second burring punch, and is provided so as to be movable along the frrst axis line in a
state where a center axis line of the second thl-ough hole coincides with the first axis
line.
The second burring punch may be PI-ovided so as to be movable along the first
axis line inside the second through hole of the second bul~ingh older in a state where a
center axis line of the second burring punch coincides with the first axis line.
The second piercing pmlch may be attached to a front end of the secotld
burring punch while having the first axis Iine as the center axis line along with the
second bul~ingp uncll.
The second external unit may include: a second burring die which has a
second forming hole into which the second burring ptinch is inserted, and is provided
so as to be movable outside the second wall portion along thc first axis line in a state
where a center axis line of the second for-ming hole coincides with the first axis lint;
and a second piercing die which has a second piercing hole into which the second
piercing punch is inserted, and is provided so as to be movable outside the second wall
portion along the first axis line in a state where a center axis line of the second piercing
hole coincides with the first axis line inside the second Cornling hole of the second
burring die.
LO03 91 I:.
(24) In the burring apparatus according to (231% the first piercing hole of the
first piercing die may include a bottom portion.
In a case where a center positio~zb etween the first wall portion and the second
wall portion on the first axis line is defined as a reference point, the first burring die
and the second burring holder may be disposed so as to [ace each other in a state where
the reference point is interposed thel-ebelween, the first piercing die and the second
btlrring punch may be disposed so as to face each other in a state ivhexe the reference
point is interposed therebetween, m~d the internal unit may further include a stopper
wl~ichp asses though the reference point and is provided so as to be movable along a
second axis Iine oi-thogonal,to the -first axis line.
The stopper may have a shape which causes the first bw~ingd ie and the first
piercing die to move toward the first wall portion and the second burring holder and
the second burring punch to move toward the second wall portion in a process in which
the stopper passes through the reference point along the second axis line.
The stopper may include a separation block ?vhicl~is separated from the
stopper when the stopper stops in a state where the first burring die and the first
piercing die come into pressure contact with an inner wall surface of the first 1vaI1
portion, and the second piercing punch attached to front ends of the second burring
holder and the second burring punch come into pressure contact with ar~in ner wall
surface of the second wall p013io11,a nd ~vl~icish l novable along the first axis tine along
with the first piercing die and the second Burring punch.
[0040]
(25) In the burring apparatus according to (24); the internal unit may further
include a die return mechanism which applies an exter~laflo rce toward the reference
point to the first burring die.
[Effects of the Invention]
[0041]
According to the aspects, it is possible to accurately and effectirrely form
blurring holes having the same axis line as center axis Iines wit11 respect to a first wall
portion and a second wall porfion facing each other:
[Brief Descsipt ion of the Dl-awjngs)
[DO421
FIG. 1 is a perspective view showing a schematic configuration of a lateral
link 1 which is an example of a product in which buuing hales are famed on a pair of
wal portions facing each.othe~
FIG 2 is a front view sl~owingth e schematic corlfiguration of the lateral link 1.
FIG. 3A is a sectional view taken along line A-A in FIG 2.
FIG. 3B is a sectional view taken along line B-B in FIG 2.
FIG. 3C is a sectional view taken alctng line C-C in FIG. 2.
FIG 3D is a sectional view taken along line D-D in FIG. 2.
FIG 4 is a flowchart showing a manufacturing process of the lateral link 1.
FIG 5A is a first explanatory view with respect to the manufacturing process
of the lateral link I in detail.
FIG. 513 is a second explanatory view with respect. to the manufacturing
pimess of the lateral link 1 in detail.
FIG. 5C is a third explanatoly view with respect Lo the manufacturing process
of the lateral link 1 in detail.
FIG. 5D is a fourth explanatory view with respect to the manufacturing
process of the lateral link 1 in detail.
FIG. 5E is.a f&h explanatory view with respect to the manufacturing process
of the lateral link 1 in detail.
FIG. 6A is a side sectional view of a burring apparatus 300 according to a first
embodiment of the present insrention.
FIG. 6B is a front sectional view of the burring apparatus 3 00 according to the
fist embodiment of the present inve-etion.
FIG. 7 is a11 explanatoly view fyith respect to a first process of a burring
method according to the first enlbodirnent of the pixsent inverition.
FIG. 8 is a first explanatory view with respecf to a second process of the
burring method according to the first enlbodiment of the present invention.
FIG. 9 is a second explartatory view with respect to tIie second process of the
burring method according to the fust embodiment of the present invention.
FIG. 10 is a third explanatory view with l-espect to the second process of lhe
butling method according to the first embodiment of the present invention.
FIG, I1 is a fourth explanatory view with respect to the second process of the
burring method according to the first embodiment of the present invention.
FIG 12 is an explanatory view with respect to a third p~vlcesso f the burring
method according to the first embodiment of the present invention.
FIG. 13A is a side sectio~~vaile w of a buning apparatus 400 according to a
second embodiment of the present invention.
FIG 13B is a front sectional view of the buwing apparatus 400 accoilding to
the seco~lde mbodiment of the present invention.
FIG 14 is an explanatory view with ~espectto a first process of a burring
met hod according to the second embodiment of the present invention,
FIG, 15 is a first explanatory view with respect to a second process of the
burring metl~oda ccorditig to the second embodiment of the present invention.
FIG. 16 is a second explanatory view with respect to the second process of the
brtcchg method according to the second embodiment of the present invetition.
HG. 17 is a third explanatoly view with respect to the second process of the
burling method accolding to the second embodiment of the present invention,
FIG. 18 is an explanatory view with respect to a third pmccss of the burring
method according to the second embodiment of the present invention.
FIG. 19A is a side sectio~lalv iew of a burring apparatus 500 according to a
third embodiment of the present invention.
FIG 19B is a f i o ~s~ectt ional view of the burring apparatus $00 according to
the third ernbodiment of the present invention,
FIG 20 is an explanatory view with respect to a first process of a bu~ring
method according to the third embodiment of the present invention.
FIG. 21 is a first explanatory view with respect to a second pl-ocess of the
burring method according to tile third embodiment of the present invention.
FIG. 22 is a second explanatory view with ~gspectto the second process of the
burring method according to the third embodiment of the present invention.
FIG 23 is a third explanatory view with respect to the second process of the
burring niethod according to the third embodiment of the present invention.
FIG 24 is a fourtl~e xplanatory view with respect to the second process of the
buming method according to the third embodiment of the presefit invention.
FIG. 25 is an explanably view with respect to a third process of the burring
method according to the third embodiment ofthe present invention.
FIG. 2GA is a side sectional view of a burring apparatus 600 according to a
fourth etnbodiment of the prese~t invention.
FIG. 263 is a front sectio~lavl iew of the burring apparatus 600 accordi~lgto
the fourth embodiment of the pre.sent invention.
FIG. 27 is an explruutor~v~ie w with respect to a first process of a b~~rring
method according to the fourth embodiment of the present invention.
. FIG, 28 is a first explanatory view with r-espect to a second process of the
burring merllod according to the fourth embodiment of the present inve~ltioll.
FIG. 29 is a second explanatory view with respect to the secoi~dp rocess of the
burring rnetlzod according to the fourth embodime~o~ft the present invention.
. FIG 30 is a third explatlatoiy view with respect to the second process of the
burring method according to the fourth embodiment of the present invention.
FIG 3 1 is a fourth explarlntory view with respect to the secorxd process of the
blaring metl~oda ccording to the fourth embodiment of the present invention.
FIG 32 is a fifth explanato~yv iew with respect to the second process of the
burring method according to the fourth embodiment of the present invention.
FIG33 is an explanatory view with respect to a third process of the burring
method according to the fourth embodiment of the present invention.
[Embodimerlts of the Lnvention]
[0043]
Hereinafter, embodiments of the present invention will be described in detail
with reference to the drawings.
First, for easy understanding of a buying apparatus and a burring method
according to the present embodiment, an example (for example, a lateral Iink which is
a lirlk structure member used in a suspension of a vehicle) of a product, in which a
burring hole is formed, is described.
FIG. 1 iS,a perspective view showing>as chematic configuration'of a lateral
Iink 1 in whicli a bush-Iloldirlg portion 20 is formed on an end portion of a steel pipe
L
(metal pipe). FIG 2 is a front view sllowing the schematic configuration of the lateral
Iink 1. FIG 3A is a secliona1 view taken along line A-A in FIG 2. FIG 38 is a
secdot~avl iew taken along line B-B in FIG 2. FIG. 3C js a sectional view taken along
line C-C in FIG. 2. FIG. 3D is a sectional view taken along line D-D in FIG. 2.
[0045]
As sllown in FIGS. 1 and 2, the lateral link 1 includes a rod portion 10, the
bush holding portion 20 which is connected to one end of the rod po~rtio10~, ~a nd a
fastening poi-tion 30 which is connected to the other end of the rod portion 10.
For example, the bush holding portion 20 can be connected to an axle by a
shaft member or the like which is fitted and inserted via a bush (not shown). The
fastening po~tion3 0 can be connected to a vehicle body (not shown) by a bolt or the
like.
[0046]
The rod portion 10 is coilfigured of a holiow steel pipe (metal pipe) in which a
cross section orthogonal to a longitudinal direction is a closed cross section. The
bush holding portion 20 and the fastening portion 30 are formed integrally with the rod
portion I0 by plastically deforming both ends of the rod pot-fion 10 by press forming.
For example, in the rod poi-tioa 10, the cross section orthogonal to the
longitudil~al direction has a ciirular peripheral wall section.
LO0471
The bush holding portion 20 includes at1 expanded and tapered pipe portion
1 1, a straight portion 12, bush holding wall portions 2 I, and widening connectio~~
po~-#io~22ls.
For; example, the bush holding wall portions 21 ace co~mectedto the rod
po~tiu~10z via the widening cam~ectionp ortions 22. Each of the widening con~~ectiol~
portions 22 is a connecti~ns hape portion which connects each of the bush tloldirig cvall.
por.tions 21 and the rod portion 10.
[004&]
The expanded and tapered pipe portion f 1 ii~cludesa conical taper in which a
diameter gradually increases from a base end side toward a front end side by plastically
deforrnillg one end of the rod portion 10. The iiu~edr ia~nteer of a front end opening
portion of the expanded and tapered pipe portio~I~1 is lager than the inner diameter of
the rod portion 10. The thickness of a peripheral wall section of the expanded and
tapered pipe portion 11 is thinner than the thickness of a peripheral wall section of the
rod portion 10.
[OD491
The straight portion 12 is connected to the front end side of the expanded and
taperedpipepor-tion 11, Theimerdiameterofthestraightportion 12is thesameas
the inner diameter of the front end opening pol-tion of the expanded and tapered pipe
portion 11. The thickness of a peripheral wall sectio~ol f the straight portion I2 is the
same as the thickness of the peripheral wall section of llle expanded and tapered pipe
portion 1 I.
[OOSO]
The pair of bush holding wall portions 21 is flat portions which extend toward
the outside in the longitudinal direction from the straight porlion 12 so as to face each
other and to be paralel to each other.
In a case in which the front end sides of the bus11 holding wall portions 2 1 are
viewed from the base end side (rod portion 10 side), as shown in FIG 3A, flat portions
are formed on the front end sides of the bush holding wall portions 21 over the elltire
widths of the bush holding wall portions 21.
Hereinafter, one of the pair of bush holding wall porlions 21 facing each other
may be referred to as a first wall portion 21 1, and the other may be refwed to as a
second nnll portion 2 12.
[oos 1 ]
In addition, a bush holding hole 24 is formed at tile center in a width direc~ion
of each of the bush holding wall portions 21. A bul~ings hape portion 25 is fomled on
a peripheral edge portion of the bush holding hole 24.
The burring shape portions 25 mn~~tuaIIeyx tend from the bush holding wall
portions (first wall portion 21 1 and second wali portion 212) 21 toward the inside
(opposite wall portion), and rising lengths of the burring shape portions 25 from the
first wall portion 21 I and the second wall portion 212 are the same as each other, and
inner circurnferentia1 diameters of the bumi ilg shape poitians 25 are the same as each
other.
Hereinafter, as described above, the bush holding hole 24, in which the
burring shape portion 25 (rising wail portions) is formed on the peripheral edge portion
by burring, may be referled to as a burring hole.
[OOSZ]
As shown in FIG. I, the pair of burring holes (bush holding holes 24) formed
on the first wall portions 21 1 and the second wall portion 212 has a first axis line X
oihogonsl to Ule fist wall portion 21 1 and the second wall portion 2 12 as the center
axis lines. In other wolds, the center axis line of one of tlze pair of burring holes and
the denter axis line of the other one of the pair of but~ingh oles coincide with the first
axis line X.
. [0053] J. *
A bush (not sho~vni)s inserted into each of bush holding surfaces 25A (refer
to FIG. 3A) which are formed on inner circumferer~ceso f the burring shape portions 25
and the bush holding holes 24, a shaft tnerxlber or the like is inserted into the bushes,
and the bus tl Iloldi~lgp orrtion 20 is connected to an axle via the bushes. In addition,
since an area (that is, area of the bush hoiding srrrface 2SA) on the inner
circz~n~ferentisaul rface of the br~shh olding 110le 24 for~nedo n the peripheral edge
portion can be Iargely secured, the burring shape portion 25 which is the rising wall
portion can stably hold the bush or tlie like.
[0054J
As showil in FIG 2 and 3B, the widening connediou portion 22 includes a
pair of wall portions, which includes bent portions in which cl-oss sections orthogonal
to the rod portion 10 approach each other and has an approximately cfiannel shape, on
both ends. The front end side of the widening connection portion 22 is connected to
the bush holding wall poriion 21, and the base end side of the widening con~~ection
portion 22 is connected to tlie front end seclio~o~f t he straight portion 12.
In addition, the widening connection portion 22 is plastically deformed such
that a V-shaped gap is fbrmed from the base end side toward the front end side in the
front view, the bent portions on both ends are shortened, and the widths of the flat
pol-iions increase.
[0055 J
As a result, the cross sectiorl of the widening connection portion 22 is fosined
in an app~vlxiinatelyc hannel shape, and the widening comcction portion 22 is formed
such that the shape is gradually changed from the chamel-s11aped cross section to the
flat portion while the width increases fro111 the base end side toward the front end side.
FIG. 3C shows a cross section when the.bush holdirlg portion 20 is viewed
from the straight portion 12 in the loi~gituditiald irection of the rod portion 10. In
addifion, FIG. 3D shows a cross section when the bush holding portion 20 is viewed
from the rod portion 10 in the longitudhl direction of the rod portion 10.
[OOSG]
In addition, in the pair of wall portioils configtiring the bush I~oldingw all
portions 21 and the widerlirlg connection portions 22, the kngth in the cmss section
ortl~ogonatlo the rod portio~1~0 is the same as the circumference of the peripheral wall
section of the straight portion 12 (except for the width of the slit which is foimed
during the rnat~ufacturingp rocess) in which the steel pipe is expanded.
[0057]
As shown in FIG. 2, the fastening portion 30 includes fastening wall portions
r
31, first separation connecfiorl portions 32, and second separation connection portions
The fastening wall portions 31 are connected to the rod portion 10 via the first
sepalation connection po~tions3 2 and the second separation connectionpo~tion3s 3.
The first separation connection portions 32 and the second separation connection
portions 33 are cofltlection shape portions which connect the fastening ~valIp ortions 3 1
and the rod podion 10.
[0058]
The fastening wall pol-tions 3 I include a pair of facing wall portions having
flat poi-tions facing each other on the front end sides. For example, in a case in which
the front end sides of the fastening wall poriions 3 1 are viewed from the base end sides
(rod portion 1 0 sides), flat poi-tions are formed over the entire widths of the fastening
wall portions 3 1 . In addition, attaclmet~ht oles 34 are fo~meda t the centers of the
fastening wall portions 3 1 in the width dir-ection.
[0059]
Far example, the frrst separation connection portions 32 include a pair of
channel-shaped wall portions which has bent portions in which cross sections
orthogonal to the rod portion f 0 approach each other on both e~~dsT. he fastening
wall poi-tiorts 31 are connected to the fiunt end sides of the first separation cont~ection
portions 32, and the second separatio~c onnection portions 33 are con~~ectetod the
base end sides of the first separation connection portions 32.
[0060]
In addition, the first separation connection potfions 32 are plastically
deformed such that a V-shaped gap in a front view is formed from the base end side
toward the front end side and widths of flat portions increase while bent polt ions on
both ends decrease, In addition, reinforcing beads wllich swell inward from the
inside and extend in the longitudinal direction are formed at the centers of the first
separation connection potqions 32 in the width direction.
[OOGlJ
The second separation connection portions 33 include a pair of appmximateIy
channel-shaped wall portions which has bent pol-tions in whiclx cross sect ions
orthogonal to the rod portion 10 approach each other on both ends. The first
separation connection portions 32 are connected to the front end sides of the second
separation co~lnectionp ortions 33 and the ~wdpo rtion 10 is connected to the base end
sides off he second sepal-ationc onnectia~pl ortions 3 3.
[0062]
111 addition, in the second sepalation connection por-tions 33, the cross sections
are fomcd in approximately channeI shapes in which bent portiolis formed 011 both
ends approach each other, and in a front view, the second separation connection
portions 33 are formed in a V shape in which the pair of wall portions is gradually
separated from each other from the base end side toward the front end side.
In addition, one reinforcing bead which swells inward from the inside and
extends in the longitudinal direction is fortned at the centers of the second separation
co~mectionp ortiolls 3 3 in the width direction.
[OW3 1
According to this configuration, the cross sections of the second separation
connection portions 33 are formed in approximately channel shapes, and the second
separation connection portions 33 are connected to the first separation connection
portions 32 while being separated from each other froin the base end sides toward the
front end sides. The cross sections of the first separation cont~ectionp ortions 32 are
formed in approximately channel shapes, and the first sepalhaito n connection portions
32 ale formed such that the cross sectiorls are gradually changed from channel shapes
to flat portions.
LO0641
In addition, in the pair of wall portions configuring the fastening wall portions
3 1, the first separation connectiorl portions 32, and the second separation connection
portions 33, the length in the cross section o~$liogonatlo the rod portion 10 is the same
as the circumference ofthe peripheral iwll section (except for the width of the slit
which is for~nedd uring the manufacturing process) of the stee1 pipe,
[OM51
Nexf, with reference to FIGS. 4 and SA to 5E, a rneiIlod for forming the bush
holding poltion 2-0 d l be described. FIG 4 is a diagram showing an example of a
flo~rcliarsth owing a manufacturing process of a Iateral Link by integrally forming the
bush holding poltion 20 on the end portion of the steel pipe.
In addition, FIGS. 5Ato 5E are views showing the li~a~~ufacturpinrogc ess in
which the bush holding partion 20 is integrally formed.
LO066 J
(1) First, for example, a pipe expa~lsionp unch (not shown) is inserted into a
'f
steel pipe I OM configuring the rod portion 10, and a fornation pla1111edp ortion 20A
for forming the bush holding portion 20 is formed (Step S 1 shown in FIG 4).
As shown in FIG. 5A, the fornlation planned portion 20A includes the
expanded and tapered pipe portion 11 in which the diameter is conically increased
fium the base end side of the steel pipe 10M toward the front end side by a pipe
expansion punch or the like, the straight pol-tion 12, and a formation planned portion
2 10 in which the bush holding portion 20 is formed, and the circamfe~.enceo f the
formation planned por-tion 20A is longer than that of the steel pipe 1 OM, and the
thickness of the formation planned portion 20A is thinner than that of the steel pipe
IOM.
(2) Next, two slits 2 105 extending in the longitudirlai direction are formed on
the steel pipe 10M, two wall portiorls 210A before press farming in which lengths in
the circumferential direction are the same as each other are provided, and a division
wall portion 20B corresponding to the bush holding portion 20 is formed (Step S2
shown in FIG 4).
For example, as shown in FIG 5B, the pair of facing wall portions 2 10A
before press forming having the same shape is formed by fornling two slits 2 1 05 at
ci~cumferentiapl ositions symmetrical to the center axis of the forination planned wall
portion 21 0. ,. .
(3) Next, the wall portions 21 0A before press forming are plastically
deformed into the bush holding wall portions 210C after press forming by press:
forming the wall portions 2 1 0A befop~l~xs s forming (Step 53 shown in FIG 4).
For example, the press formirig is performed according to procedures shown
in FIGS. 5C to 5E.
1) First, as shown in FIG. SC, the steel pipe 10M is set by a press rl~oldK l,
and a punch K2 advances in the axial direction of the steel pipe 1 OM and is inserted
into the wall portions 210A before press forming,
2) Next, as show in FIG. 5D, each of the slits 2105 is formed in an
app~*oximatelVy- shaped slit 210T by advancing the puncl~K 2, the wall portions 210A
before press forming ale plastically deformed into intermediate shape wall portions
2 10B in which bent portions are formed an both ends in the width direction and the
bent portions are shortened toward the front end sides such that the shapes are changed
to the flat poitions, and an intermediate wall portion 20C of the bus11 holding portion
20 is formed.
3) Next, as shown in FIG. SE, each of the sIits 210T is formed to a slit 210U
by advancing the punch K2 to the advance end, the intermediate shape wall portions
2 1 0B are formed to the bush holding la1 1 partions 2 1 0C after press forming, and a
bush holding portion 20D before trimming is formed, which corresponds to the bush
holding portion 20 in which the front ends are sepaiated from each other at
approximately the same interval as the outer diameter of the expanded steel pipe 1OM.
According to the processes, the pair of bush holding wall portions 21 (first
wall portion 2 11 and second wall po~fion2 1 2) is formed, 1v1lich face each other and
extends from the straight portion 12 to the outside in the longitudinal direction so as io
be parallel to each other.
(4) Next, prepared lmles are formed, which I~aveth e first axis line X as the
center axis lines with respect to the first wall portion 211 and the seco~lcwl all podion
212 using a burring apparatus and a burring method of the present ernbodirnent
described below (Step S4 shown in FIG. 4).
(5) Finally, the bush holding holes 24 having the burring shape portions 25
which are the rising wall portions are foriiled by bending the peripheral edge portions
of the prepared hotes formed on the first wall portion 2 11 and the second wall portion
212 in the direction along the first axis line X using the btrrring apparatus and the
burring methad of the present ernbadi~nent(S tep S5 sho\vrt in FIG. 4).
According to the processes, the lateral link 1 is completed, in which the
burring hales (bash holding holes 24) having the first axis line X as the center axis
lines are formed with respect to the first rval l portion 2 1 1 and the second wall portio~~
2 12 (the pair of bush holding wall portions 21).
10067 J
Hereinafier, the bul~inga pparatus arid the burring method of the pi~seiit
embodiment used in the above-described steps S4 and S5 will1 be described in detail.
, [0068]
[First En~bodiment]
First, a bul~inga pparatus and a buning method according to a first
embodimentofthepresentinvention~villbedescribed. Inthefirstembodiment,as
shown in FIGS. 1 and 2, a buzring apparatus and a bu~ringm ethod for forming the
burring hole having the rising wall portion which is bent toward the inside of the first
wail portion 2 1 1 011 the first wall portion 2 1 1, and the burring hole having the rising
wall portion which is bent towal-d the inside of the second wall portion 212 on the
second wall portion 212 will be described.
[OM91
Moreover, in both sides of the first walI portion 21 1 on thefirst axis line X,
the side on \1#1ic11th e second-wallp ortion 212 exists is defined as an "inside of the first
wall portion 21 I", and the opposite side is defined as an "outside of the first wall
poltion 21 1". In addition, in both sides of the second \vat1 pol-tion 212 on the first
axis line X, the side on which the first wall portion 21 I exists is defined as an "inne~
side of the second wall. portion 212", and the opposite side is defined as an "outer side
of the second waI t portion 212".
[0070]
FIG. 6A is a side sectional view of e burring apparatus 300 according to the
first embodiment. FIG. GB is a front sectional view of the burring apparatus 300
accol*ding to the first embodiment.
As shown in FIG. GA, a center position between the first wall portion 211 and
the second wall portion 2 I2 on the first axis line X is defined as a reference point P,
and an axis line which is orthogonal to the first axis line X thnugh the reference point
P and is parallel to the extension directions of the first wall portion 21 1 and the secand
wall portion 212 is defined as a second axis line Y. The second axis line Y coincides
with the center axis line of the lateral link 1. That is, FIG 6A is a view when the
burring apparatus 300 is viewed along a cross section including the first axis line X
and the second axis line Y,
In addition, as shown in FIG GB, an axis line which is orthogonal to the first
axis line X and the second axis line Y through the reference point P is defined as a third
axis line 2. The third axis line Z is pal-allel to the width directions of the first wall
portion 211 and the second wall portio11212. That is, FIG 6B is a view when the
burring apparatus 300 is viewed along a cross section (cross section orthogollal to the
second axis line Y) including the first axis Iine X and the third axis line 2.
., [0071] .-
As shown in FIGS. 6A and GB, the burring apparatus 300 includes a first
external unit 3 10 mrhich is disposed outside the first wall portion 21 1, a secorld external
unit 320 which is disposed outside the second wall portion 212, and an internal unit
330 which is disposed betsveen the first wall portion 211 and (he second wall portion
2 12.
[0072] .. ..
In the descriptions below, a piercing punch is a shaft menlbcr for fornming a
prepared hole for burring on the first wall portion 21 1 and the second wall portion 21 2.
In addition, a burring punch is a sllaft nlember for forming bui~ingh oles haviilg rising
wall portions by bending the peripheral edge portions of the prepared holes in the
direction along the first axis line X.
100731
The fixst external uulit 3 10 includes a first piercing punch 3 11, a first burring
punch 3 12, and a fi~stb uning holder 3 313.
KO0741
The first piercing punch 3 t 1 is a columnar shaft member for forming the
prepared holes on the first wall portion 21 1. The first burring punch 3 12 has the first
axis IineX as the center axis line along rvith the first piercing punch 311 and is a
cylindrical sM member for forming the burring holes on the first wall poxtion 211 by
bending the peripheral edge pol-tion of the prepared hole of the first wall paltion 21 1 to
the inside of the first wall portion 21 I. Both end surfaces of the first burring punch
312 are open such that the first piercing pui~cli3 1 1 can be inserted into the first burring
punch 3 12.
[0075]
,.. The first burring holder 3 13 is a circular thickplate member which has a first
through hole 3 13a serving as a passage of the f ~ sbtu rring punch 3 1 2. The first
tlirough 1101e 3 13a is a circular hole which penetrates in a plate thickness direction of
the first bur~ingh older 3 13 and has the same center axis line as the center axis line of
the first burring holder 3 1 3.
[0076]
The first burring holder 3 13 is provided so as to be movable outsidc the first
wall portion 21 1 along the first axis line X in a state where the center axis line of the
first through hole 3 13a coincides with the first axis line X. Tn addition, the first
burring holder 3 13 has a flat surface 313b ~vl~icchan come into surface coiltact with an
outer wall surface 21 la of the first watt portion 211.
[0077]
The first burring punch 3 12 is provided so as to be movable between the
outside and the inside of the first wall portion 21 1 along the first axis line X inside the
first though hole 313a of the first burring holder 3 13 in a state where the center axis
line of the first bul~ingp unch 3 12 coincides with the first axis line X.
[0078j
The first piercing punch 3 1 1 is provided so as to be movable between the
outside and the inside of the first wall portion 21 1 along the first axis line X inside the
first burring punch 3 12 in a state where the center axis line of the first piercing punch
311 coincideswitl~thefirsta xislineX. Thatis,aninternalsl>aceofthefirstb u~~ing
punch 3 12 tav3ng a cyli~ldricasl hape is used as a passage of the first piercing punch
311.
COO791 , -
As described above, in the first external unit 3 10, the first piercing punch 3 11,
;I the first burring punch 3 12, and the first bur~ing.holder3 13 have the first axis line X as
the center axis lines.
[0080]
In addition, in the first external unit 3 10, preferably, an inner circumfel*ential
surface of the first burring. hoIder 3 13 (a surface of the fmt though 11oIe 3 13a) and an
outer circumferentiaL surface of the first burring pmlch 3 12 come into close co~ltact
with each other* In addition, preferably, an irmer circumferential surface of the first
burrit~gp unch 3 I2 and an outer circumfcrcntial surface of the first piercing punch 3 11
come into dose contact with each other.
Accordingly, wIreti the first piercing punch 3 11 and the first burring punch
3 12 move along the first axis line X, it is possible to prevent the center axis lines of the
first piercing punch 3 11 and the first burring punch 3 12 froin being deviated from the
first axis line X.
[OOS 11
The second external unit 320 includes a second piel0cing punch 32 1, a second
buwing punch 322, and a second burring holder 323.
[OOSZ]
The second piercing punch 321 is a columnar shaft member for forming thc
prepared holes on the second wdl portion 2 12, The second buning punch 322 has the
first axis line X as the center axis line along with the second piercing punch 321 and is
a cylinblicd shaft member for forming the burring holes an the second wall portion
212 by bending the peripheral edge portion of the prepared hole of the second wall
portion 2 12 to the inside of the second wall portion 21 2. Both end surfaces of the
second burring punch 322 are open such that the second piercing punch 32 1 can be
inserted into the second butring puncl~3 22,
[0083]
The second barring holder 323 is a circular thick plate member which has a
second through hole 323a sei-ving as a passage of the secorzd burring punch 322. The
second through hole 323a is a circular hole which penetrates in a plate thickness
direction of the second burring holder 323 and has the same center axis line as the
center axis line of the second bu~~irilhlgo lder 323.
[0084]
Tile second bu~~ihnogId er 323 is provided so as to be nzovable outside the
second ~valpl oition 212 along the first axis line X in n state where the center axis line
of the second tlmugh hole 323a coincides with the first axis line X. In addition, the
second burring holder 323 has a flat surface 323b which can come into surface contact
with an outer wall surface 2 12a of the second lvdl pm.tion 212.
[OOSS]
The second burring punch 322 is provided so as to be movable between the
outside and the inside of tile second wall portion 212 along the first axis line X inside
the second ?lll.ough hole 323a of the second burring holder 323 in a state where the
ce~ltera xis line of the second b u ~ ~ i pnugn ch 322 coincides with the first axis line X.
[OO 861
The second piercing punch 32 1 is provided so as to be movable between Ihe
outside and the inside of the second wall poition 212 along the first axis line X inside
the second burring punch 322 in a state where the center axis line of the second
piercing punch 321 coincides with the fust axis line X. That is, an internal space of
the second burring punch 322 having a cylindrical shape is used as a passage of the
second piercing punch 3 2 1.
[0087]
As described above, in the second external unit 320, the second piercing
punch 321, the second burring punch 322, and the second burring l~older3 23 have the
first axis line X as the center axis lines,
[0088]
In additiotl, in the second exteo~alu nit 320, preferably, an inner
circumfere~~tiasul rface of the second burrkg holder 323 (a surface of the second
thru~lghh ole 323a) and an outer circumferential surface of the second burring pr~nch
322 come into close corltact with each other. In addition, preferably, an inner
circumfel-ential surface of the second b u ~ ~ i pnugn ch 322 and an outer circumferential
surface of the second piercing plinth 321 come into dose contact with each other.
Accordingly, when the second piercing punch 32 1 and the second burring
punch 322 move along the first axis line X, it is possible to prevent the center axis lines
of the second piercing punch 321 and the second burriitlg punch 322 from being
deviated from the first axis line X.
[0089]
The hternaI unit 330 indudes a housing 33 1, a first burring die 332, a first
piercing die 333, a second burring die 334, a second piercing die 335, a first stopper
334, and a second stopper 337.
[0090]
The housing 33 1 is a cylindrical member which includes the first burring die
332, the first piercing die 333, the second burring die 334, and the second piercing die
335 and in which both end surfaces are open. The housing 331 is disposed between
the first wall portion 211 and the second ~vaHp ortion 212 in a state where the center
axis line of the-housing coincides with the first axis line X. In addition, the housing
33 1 includes a first opetling poi-tion 33 1 a and a second opening portion 33 1 b which are
open to have sizes of the openings tluvug h which the first stopper. 3 3 6 and the seco~ld~
stopper 337 can pass along the second axis line Y.
(009 1 j
The first burring die 332 is a cil.cular thick plate nlernber having a fir-st
forming hole 332a into which the first burring punch 3 12 is inserted. Tile first
forming hole 332a is a Jrcuiar hole which perletrates along the plate thickness
direction of the first burring die 332 and has the same center axis line as the center axis
fine of the first burring die 332. Preferably, the diarneter of the first forming hole
332a has the satne value as the sum of the outer diameter of the first burning punch 3 12
and the thickness of the first wall portion 211.
to0921
The first burldingd ie 332 is provided so as to be movable inside the first wall
portion 21 11 along the first axis line X inside the housing 33 1 in a state where the center
axis line of the first fonnit~gh ole 332a coincides with the first axis line X. In addition,
the first burring die 332 includes a flat surface 332b which can come into surface
contact with an inner wall surface 21 1 b of the first wall portion 211 and an inclined
surface 332c which is inclined in a direction toward the frrst wall portion 21 1 with
respect to the second axis line Y.
[0093]
The first piercing die 333 is a circular thick plate member having a first
piercing hole 3 33a into which the first piercing punch 3 1 1 is inserted. The first
0 piercing hole 333a is a circular hole which penetrates along the plate thickness
direction of the fmt piercing die 333 and has the same center axis line as the center
axis line of the first piercing die 333. Preferably, the diameter of tIie first piercing
hole 333a is the same as the outer diameter of the first piercing punch 311.
roo941
The first piercing die 333 is provided so as to be movable inside the first wall
portion 21 1 along the first axis line X inside the first forming hole 332a of the first
burring die 332 in a state where the center axis line of the first piercing hole 33 3a
coincideswithtl~efi~~staxislineXIn. addition, thefirstpiercingdie333 incIudesa
flat surface 333b which can come into surface contact with an inner wall surface 21 1 b
of the first wall portion 2 1 1 and an inclined surface 33 3c which is illcli~~ei1 d1 the
direction toward the first wall portion 21 1 with I-espect to the second axis line Y, The
inclination angle of the irlclined surface 333c of the first piercing die 33 is the same as
the inclination angle of the inclined surface 332c of the first burring die 332.
[OOSS] . -..
The second burring die 334 is a circular thick plate member having a second
forming bole 334a into which the second burring punch 322 is 'inserted. The second
forming hole 334a is a circular hole which penetrates along the plate thickness
direction of the second burring die 334 and has the same center axis line as the center
axis line of the secot~d buuing die 334. Preferably, the diameter of the second
forming hole 33421 has the same value as tlie sum of the outer diameter of the second
burring punch 322 and the thickness of the second wall portion 2 12.
roo961
The second burring die 334 is provided so as to be movable inside the second
wall portion 212 along the filst axis line X inside the housing 331 in a state wher-e the
center axis line of the second forming hole 334a coincides with the first axis line X.
In addition, the second burring die 334 includes a flat surface 334b which can come
into surface contact with an inner wall surface 21 2b of the second wall po14ion 21 2 and
an inclined surface 334c which is iilclined in a direction toward the second wall portion
212 with respect to the second axis line Y.

Document Type] CLAIMS
What is claimed is:
I
1. A burling method for forming btn.l'ing holes having a first axis line as center
axis lines with respect to a first wall portion and n second wall portion facing each
other, the burring method comprising:
a first process of disposing an internal unit of a b~~l-rinapgp aratus betweal the
first wall portion and the second wall poltion, disposing a fust external unit of the
burring apparatus outside the first 1val1 portion, and disposing a second external unit of
the bul~illga pparatus outside the second wall portion;
a second process of, out of a piercing punch and a bu~r.ingp unch which ale
shaft members having the first axis line as the center axis lines provided in at least one
of the internal unit, the first external unit, and the second external unit, and are
provided so as to be movable along the first axis line, first, forming prepared holes
having the first axis lii~esa s the center axis lines with respect to the first wall portion
-and the second wail portion using the piercing punch, md thereafter, forming burring
lloles having the first axis line as the center axis lines with respect to the first wall
portion and the second wall poi-tiot~u sing the burring punch; and
a third process of detaching the internal unit, the first external unit, and the
secai~de xternal unit-from the first waI1 pot-tion and the second wall portion.
2, . The b11uing method according to Claim I ,
wl~ereinin the second process,
after one of the prepared lloles is foulled on the first u \ d l portion using a first
piercing punch provided in the first external unit, one of the burring holes is fonned by
. . bending a peripheral edge portion of the prepared hole of the first wall portion to the
inside of the first wall portion using a first burring punch which is plaovided in the first
external unit and has the first axis line as the center axis line along with the first
piercing punch; and
after the other prepared hole is formed on the sccond wall polZion using a
I
second piercing punch provided in the second external unit, the other burring hde is
fol+mned by bending a periplerai edge poltion of the piAeparedh ole of the second wail
portion to the inside of the second wall portion using a second b~trringp unch which is
provided in the second external unit and Iias the first axis line as the center axis line
along with the second piercing puilch.
3. The burring method according to Claim 2,
wherein in the frrs t process,
among a first burring holder which is provided in the first external unit and
has a first though 110le serving as a passage of the first burring punch, the first burring
. punch which is disposed inside the first through bole, and the first piercing punch
which is disposed inside the first burring punch, the first burring holder and the first
bur.l.ing punch come into pressure contact with an outer wall surface of the first wall
portion in a state where center axis lines of the first through hole, the first piercing
punch, and the-first burring punch coincide wit11 the first axis line;
among a second burring holder which is provided in the second extenlal unit
. and has a secood though hole serving as a passage of the second brrrring puncl~t,h e
second burring punch whicIi is disposed inside the second through I~olea, nd f he seconcl
piercing punch which is disposed inside the second burring punch, the second burling
holder and the second burring plltlcl~c ome illto pressure contact with an outer wall
surface of the second wall portion in a state where center axis lines of the second
through hole, the second piercing pnnch, and the second burring punch coincidc wit11
the first axis line;
a first burring die wllich is provided in the internal unit and has a first forming
hole, and a first piercing. die which is provided inside the first forming hole and has a
first piercing hole come into pressure contact with an inner wall surface of the first
wall portion in a state where center axis lines of the first forming hole and the first
piercing hole coincide wit11 the f ~ satx is tine; and
a second bu~r.lngd ie which is provided in the intend unit and has a second
forming hole, and a second piercing die wl~ichis provided inside the second forming
hole and has a second piercing hole come into pressure contact with an inner wall
surface of the second wall portion in a state where center axis lines of the second
forming hole and the second piercing hole coincide with the first axis line, and '
wherein in the second process,
one of the prepared holes is formed on the first wall portion by moving the
first piercing punch from the outside of the first wall portion to the inside thereof along
the first axis line such that the first piercing punch is inserted into the first piercing
hole;
the o tiler prepared hole is formed on the second wall portion by moving the
second piercing punch frern the outside of the second wall portion to the inside tl~ereof
along the fimt axis line such that the second piercing pux~ch is inserted into the second
piercing hole;
the peripheral edge poliion of the prepared hole of the first tvall portion is
bent to the inside of the first wall portion to form one of the burring holes by moving
the first burring pul~clfi rom the outside of the first wail portion to the inside thereof
along rhe first axis line such that the first burring punch is inserted into the first
forining hole, and the first piercing die is returned to a position close to a center
betweeti the first waIl portion and the secorld waif portion;
the peripheral edge portion of the prepared hole of the second wall portion is
bent to the inside of the second wall portion to form the other burring hole by moving
the second burring punch from the oltrtside of the second wall portion to the inside .
thereof along the first axis line such that the second burring putlch is inserted into the
second forn~ingh ole, a i d ithe second piercing die is returned to a position close to the
center between the first wall portion and the second wall portion; and
the first burring die and the second burring die are ~.ehinedto the position
close to the center behveen the first wall portion and the second wall portion after both
of the burring holes are formed.
4. The burring method according to Claim 3,
wherein in the first process,
the first burring die comes into pressure contact wit11 the inner'ivall surface of
the first wall portion and the second burring die comes into pressure contact wit11 the
imer wall surface of the second wali portion by inserting a first stopper into a portion
between the first burring die and the second bulring die in the internal unit; and
tlw fmt piercing. die comes into pressure contact wit11 the h e r wall surface of
the first wall portion and the secor~dp iercing die comes into p~cssurec ontact with the
inner wall sulfate of the secol~d' 1 ~ 1p1o ltion by inserting a second stopper into a
portion between the first piercing die and the second piercing die, and
wherein in the second process,
after the second stopper is removed fimm th.e portion between the first piercing
die and the second piercing die, one of the burring holes is foimed on the fuxt wall
po~.tionb y inserting the first burring punch illto the first fornling hoie, and the other
burring hole is formed on the second wall poi.tion by inselling the second burring
punch into the seco~zdf orming hole; and
after both of the bul~ingh oles are formed, the first stopper is removed from
the portion between the first burring die and the second burring die, and the first
burring die and the second burring die are returned to the position close to the center
between the first wall portion and the second wall portion by applying an exterilal
force to the first burring die and the second burring die in a direction approaching each
other.
5. The burring mnethod according to Claim 1,
wherein in the second process,
after one of the prepared holes is formed on the first wall portion using a first
piercing punch provided in the fmt external unit, one of the burring holes is formed by
bending a peripheral edge portion of the prepared hole of the first wall-pol-tiont o the
outside of the first wall pottion using a first burring punch which is provided in the
internal unit and has the first axis line as tho center axis line aIong with the first
piercing punch; and
after the-sther-prcpared hole is formed on the second wall portion using a
second piercing punch provided in the second external unit, the other burring hole is
formed by bellding a peripl~eraf edge portion of the prepared hole of the second rvall
powtiou to the outside oft he second wall portion using a secor~db urring punch wIiich is
provided in the internal unit and has the first axis line as the ce~ltera xis line along with
the second piercing punch.
G. The burring rnethod according to Claim 5,
wherein in the first process,
alnoilg a first burring die which is provided in the first external unit and has a
first forming ho1e;a first piercing holder which is provided inside the first forming
hole and has a first through hole serving as a passage of the first piercing punch, and
the fir*st piercing punch which is provided inside the first through hole, the fmt burring
die and the first piercing holder come into pressure contact with an outer wall surface
of the first wall portion in a state whete center axis lines ofthe first forming hole, the
first through hole, and the first piercing punch coincide with the first axis line;
among a second buuing die which is provided in the second external unit and
has a second forming hole, a second piercing hoIder which is provided inside the
second farming hole and has a second tl~lrrugl1i1 0113 seiYing as a passage of the second
piercing punch, and the second piercing punch which is provided inside the second
through hole, the second burring die and the second piercing holder come into pressure
contact with an outer wall surface of the second wall pollion in a state where center
axis lines of the second forming hole, the secot~dtl vough hole, and the second piercing
punch coincide with the first axis line; and
after a tubuIar Iiousing ~vl~icish p rovided in the iriter~~ualn it, includes the first
burring punch aid the second burl-i~igp unch, and bas both opened ends is disposed
betwen the first wall portion and the second wall portion in a state where center axis
lines of the first burringpunch, the second burring punch, and the housing coincide .
with the iimt axis line, the first bwing punch comes into pressure contact with an
inner wall surface of the first wall portion, arid the second burring put~cli comes into
pressure cor~tacwt ith an inner wall surface of the second \vat1 portion, and
wherein in the second process,
one of the prepared holes is formed on the first ~ ~por1tion1 by moving the
first piercing punch fium the outside of the first wall pol-iion to the inside thereof along
the first axis Iine such that the first pieicing punch is insertcd into the first piercing
11ole provided in the first burring punch;
the other prepared hole is formed on the second wall poi-tion by moving the
second piercing punch from the outside of the second wall polTion to the inside thereof
along the first axis line such that the second piercing punch is inserted into the second
piercing hole provided in the first burring punch;
the periphel-al edge portion of the prepared hole of the first wall portion is
bent to the outside of the first waIl portior~to forin one of the burring l~olebs y moving
the first burring punch from the inside of the first wall poltion to the outside thereof
along the first axis Iine such that the first burring punch is inserted into the frrst
forming hole;
the peripheral edge portion of the prepared hoEe of the second wall portion is
bent to the outside of the second wall portion to form the other buuing hole by moving
the second burring punch from the inside of the seco~~wda ll portion to the outside
thereof along the first axis line such illat the second burring punch is inserted into the
second forming hole; and
the first burring punch and the second burring putlch are returned to the
position close to the center between the first wall portion and the second wall portion
after both of the bur~ngho les are formed.
7. The burring method according to Clairn 6,
wherein in: the first process,
the fi~-st.bu~l.ipnugn ch comes into pressure contact with the inner wail surface
of the first wall portion and the secoi~db ui.rhg punch comes into pressure contact tvi th
the i~merw all surface of the second wall poition by inserting a stopper in110 a portin11
between the first burring punch and the second bwing punch in the internal unit, and
wherein i11 the second process,
the first burring punch moves from the inside of the first wal I poi*lion to the
oirtside tlre~oafl ong the first axis line to form one of the burring holes an the first mall
portion &d the second burring punch moves from the inside of the second wall portion
to the outside thereof along the first axis Iine to form the otlm burring hole on the
second wall portion by inserting the stopper deeper into the portion between the first
bu~.ringp unch and the second burring punch; and
after both of the bul-ring holes are formed, the stopper is removed from the
portion between the first burring punch and the second burring punch, and the first
burring die and the second burring die are returned to the position close to the center.
between the first wall portion and the second wall portion by applying an external
force to the first bueeing die and the second burring die in a direction approaching each
other. ,
8. The burring mett~odlaccoidintgo Claim 6,
nkrzin4n.the first process,
the first burring punch comes into pressure contact with the inner wall surface
of the first rvall portion and the second bul-rirrg punch comes into pressure coiltact with
the inner wall surface of the second wall portion by inserting a stopper illto a portion
between the first burring putlcf1 and the second burring punch in the infernal unit, arid
wherein in the second process,
after the prepared hole is for~iiedo n each of the first wall port ion and the
second wall portjon using the first piercing purlcll and the seco~ldp iercing punch;
by moving the second piercing punch toward the first wall poition along the
frrst axis lhe in a state where a front end of the second piercing punch comes into
corltact with a bottom po14io11 of the second piercing hole of the second burring punc11,
the second burring punch, a separable separation block provided inthe stoppef; and the
first burring punch simultaneously move toward the outside of the first wall portion
along the first axis line to form one of the burring holes on the first \vat 1 portion;
by inoving the first piercing punch toward the second wall portion along the
first axis line in a state where a front end of the first piercing punch comes into contact
with a bottom portion of the first piercing hole of the first buwing punch, the first
burring; punch, the separation blockpluvided in the stopper, and the second burring
punch simultaneor~slym ove toward the outside of the second wall porkion along the
first axis line to form the other burring hole on the second wall pol-tion; and
by moving the second piercing punch toward the first \will portion along the
first axis line in a state where the front end of the second piercing punch comes into
contact rvith the bottom portion of the second piercing hole of the second burring
puilch, the separation block is returned into the stopper.
9. The bunjt~gm etl~oda ccording to Claim 1,
wl~erein in the second process,
a@er one of the prepared Iloies is formed on the first wall portion using a first
piercing punch provided in the first externat unit, one of the burring 1oIes is formed by
bending a peripheral edge portion of the prepared hole of the first wall poition to the
inside of the fii-st wall poi.tion using a first burring punch which is provided in the first
external tinit and has-the first axis line as the center axis jir~ea long nritl~th e first
piercing punch; and
after the other prepaiaed hole is formed on the second wall portio~zu sing a
second piercing punch provided in the ii~ternalu nit, the other burring hole is fotmed by
bending a peripheral edge portion of the prepared hole of the secotld wall portion to tl~c
outside of the second wall pollion using a second buwing punch ~vl~icish p rovided in
the internal unit and has the first axis line as the center axis line along with tlle second
piercing puuch.
10. The burring method according to Claim 9,
wherein in the first process,
among a first burring holder which is provided in the first external unit and
has a first through hde serving as a passage of the first burring punch, the first burring
punch which is disposed inside the first through hole, and the first piercing punch
which is attached to a front end of the first burring punch, the first burring holder
comes into pressure contact with an outer wall surface of the first wall portion in a
state w11er-e center axis lines of the first through hole, the first burl-ing punch, and the
first piercing punch coitlcide with the first axis line;
a fitst burring die which is provided in the internal unit arrd has a first forming
hole, arid a.firstbpiercing die ~vhichis provided inside the first forming hole and has a
first piercing llde come into pi.essul-e contact with an inner wall surface of the first
wallqoltion ia a state wflere center axis lines of the first forn~ingh ole and the firs1
piercing llole coincide with the first axis line;
among a second burring holder which is provided in the internal unit and has a
second th~uglhlo le serving as a passage of the second burring punch, the second
burring pmlch ~vl~icish d isposed inside the second through hole, and the second
piercing punch which is attached to a front end of the second burring punch, the second
bul~ingh older comes into pressure contact with. an inner wall surface of the second
wall portion in a state where center axis lines of the second though hole, the second
burring punch, and the sewnd piercing punch coincide with the first axis 1 ine; and
a second buwing die which is provided in the second external unit and has a
second fonning hole, and a secorid piercing die which is provided inside the second
forming hole and has a second pielvitig hole come into pressure contact with an outer
wall surface of the second wall por-tion in a state where center axis lines of the second
forming hole and the second piercing i~olec oincide with the first axis line, and
wherein in the second process,
one of the prepared holes is formed on the first wall portion by moving the
first burring punch and the first piercing punch from the outside of the first wall
portion to the inside thereof along the first axis line such that the frwst piercing punch is
inserted into the first piercing hole;
by moving the first burring puuch from the outside of the first wall portion to
the inside thcrcof dong the first axis line such that the first burring punch is inserted
into the first forming hole after the prepared hde is formed on the first wall portion,
the periphera1 edge portion of the prepared hole of the first wall portion is bent to the
inside of the f r ~wt ~ llqm~tttioo-~fo~n n one of the bul~ingh oles;
by ~novitigth e first burring punch toward the second wall portion in a state
..w here the front end of the frrst piercing punch con~es-intcoo ntact with the botton~
portion of the first piercing hole, the second burring ptirlch and the second piercing
punch move fium the inside of the seco~~wdal I portion to the outside thereof along the
first axis line to form the other prepared hole on the second wall portion such that the
seconcl piercing.punch is inserted inlo the second piercing hole;
by further moving the first burring punch toward the second wall y oltion after
the prepared lm1e is formed on the second wall port ion, the secoild burring punch
inoves from the inside of the second wall portion to the outside thereof along the fiist
axis line such that the second burring purlch is inserted into the second forming hole,
and a peripheral edge of the prepared hole of the second wall portion is bent to the
outside of the second wall portion to form the other burring hole; and
by nloving the second burring punch to the inside of the second wall portion
after the burring hole is formed on the second wall portion, the first burring die and Ihe
fist piercing die are returned to a position close to the center between the first wall
poltion and the second walI portion.
11. The buwing method according to Claim 10,
wherein in the f i r s t process,
by inserting a stopper into a portion between the first burting die and the
secorld burring holder in the internal unit, the first burring die and the first piercing die
disposed inside the first burring die cotme into pressure contact with the inner wall
surface of the first wall portion, and the seco~~budr ring liolder. and the second piercing
punch disposed inside the second bur~.ingh older come into pressure contact with the
inner wall s~trfaceo f the second wall portion, and
wherein in the second process,
... after the prepared hole is formed on the,first wall portion, by moving the first
burring punch toward the second wall porlion along the first axis line in a state ~+lherac
front end of the first piercing punch comes into contact wit11 a bottom poition of the
first pieicing hole of the first pielring die, the first piercing die, a separable separatiorl
block provided in f he stopper; and thc second burring punch to which the second
piercing pttnch is attached sin1ultaneo11sty rllove tox-uard the second wall portion along
the first axis line, and after the burring hole of the first wall portion and the prepared
hole of the second wall polZion are sin~ultaneouslyfo rmed, finally, the burring hole of
the second wall portion is formed;
after the separation block is reh~medil lto the stopper by moving the first
piercing die, the separation block, and the second butsting punch to the inside of the
second wall portion, the stopper is removed fiom the portion betwee11 the first bur~ing
die arld the second burring holder; and
the first burring die is returned to tile position close to the center between the
first wall portion and the second wall portion by applying an external force to the first
burring die in a directbn toward the second wall portion.
12. A burring apparatus for forming burring holes having a first axis line as center
axis lines with respect to a fust wall portion and a second wall porfion facing each
othel; the burring apparatus conlprising:
an internal unit which is disposed beheen the first wall portion and the
second wall portion;
a fil-st external unit which is disposed outside the first wall portion; and
a second external unit ivhich is disposed outside the second wall portion,
wherein at least one of the internal unit, the first external utlit, and the second
external unit i~~cIudae sy ie~~ipnugn ch and a burring puuch wllich are shaft members
having the first axis line as the center axis lines and are provided so as to be movable
along the first axis line,
wllerein the first externa1 unit includes:
a first piercing punch wl~ichfo rms a prepared hole on the first wall poition;
a first burring punch wlich has the first axis liw as the center axis line along
with the first piercing punch, and bends a peripheral edge portion of the prepared hole
of the first wall portion to the inside of the first wall portion to form the burring hole,
and
wherein the second external unit includes:
a second piercing punch which folms a prepared hoIe on the second wall
por+tion; and
a second burning punch which has the first axis line as the center axis line
along with the second piercing punch, atld bends a peripheral edge portion of the
prepared I~oleo f the second wall portion to the inside of the second wall portion to
form the burring hole.
14. The burring apparatus according to Claim 13,
whereit1 the first extellla1 unit further it~cludesa first burring holder which has
a first through hole serving as a passage of the first burring punch and is provided st, as
to be movable outside the firsst waII poriio~in~ a state where a center axis Iine of the
filst though hole coincides with the first axis line,
wherein the first burring punch is provided so as to be movable between the
outside and the inside of the fit-st wall portion along the first axis line in a state where a
center axis line of the first burring punch coincides with the first axis line inside the
first through hole oft tie first burring Iloldel;
wherein the first piercing punch is provided so as to be movable between the
outside and the inside of the fii.st wall portio~al long the first axis line in a state where a
center axis line of the first piercing punch coincides with the first axis line inside the
first burring p~mch,
wherein the secorld external unit further includes a second burring bolder
which has a second through hole serving as a passage of the second burring punch and
is provided so as to be movable outside the second wall portion in a state where a
center axis line of the second through hole coincides with the first axis line,
wherein the second burring punch is provided so as to be movable between
the outside and the inside oft he second wall portion along the fust axis line in a state
where a center axis line of the second burring punch coincides with the first axis line
inside the second through hole of the second bul-ring holder,
wherein the second piercing punch is provided so as to be movable between
the outside and the inside of the second mall poition along the first axis line in a date
where a center axis line of the second piercing punch coincides with the first axis line
inside the second burring punch, and
wherein the internal unit Includes:
a frrst bu~ingdi e which has a first forming hole into which the first bu~~ing
punch is inserted, and is provided so as to be movable inside the first wall portion
along the filst axis line in a state where a center axis line of the first forming hole
coincides with the first axis line;
R first piercing die wbicii has a first piercing hole iuio wflich the first piercing.
put~chis inserted, and is provided so as to be movable inside the first wall portion
alorxg the fir-st axis lihe in a state where a center axis line of the first piercing IloIc
coincides wit11 the first axis Iine inside the first forming IzoIe of the first burring die;
a second burring die which has a second forming bole into which the second
burring punch is inserted, and is pl-ovided so as to be movable inside the second wall
portion along the first axis line in a state where a center axis line of the second forming
hole coincides with the first axis line; and
a second piercing die wkicl~h as a second piercing hole into which the second
piercing punch is inserted, and is provided so as to be movable inside the second wall
portion along the first axis line in a state where a center axis line of the second piercing
hole coincides with the first axis line inside the second forming hole of the second
burring die.
15. Theb~~rjng~pparaiusaccordingfoCIaim14,
wherein in a case where a center position between the first wall portion and
the second wall portion an the first axis line is defrned as a reference point,
the first bui~ingd ie and the second burring die are disposed so as to face each
other in w state where the reference point is interposed therebetlveen;
the first piercing die and the second piercing die are disposed so as to face
each other in a state where the reference point is interposed therebetween;
the internal unit further includes a first stopper and a second stopper which
pass though the reference point and are provided so as to be movable along a second
axis line orthogo~lal-l-ot bfi rst,a xis line;
the first stopper has a shape which causes the first burring die to move toward
the first wall po~.tiona nd the secorld burring die to move toward the second wall..
portion in a process in which the first stopper passes through file reference point along ,
the second axis line; and
the second stopper has a shape which causes the first piercing die to move
toward the first wall pol.tion and the second piercing die to move toward the second
wall portion in a process in which the second stopper passes through the reference
point along the second axis line.
16. The burring apparatus according to Clairn 15,
wherein the internal unit further includes a die return ~nechclllismw hich
separately applies an exte~naflo rce toward the reference point to each of the first
burring die and the second burring die.
17. The burring apparatus according to Clainl 12,
wherein the first external unit includes a first piercing punch which forms a
prepared hole on the first wall portion,
wherein the second external unit includes a second piercing punch which
forms a prepared hole on the second wall portion, and
ivl~ereinth e internal unit incIudes:
a first burring punch which has the first axis line as the center axis line along
with the first piercing punch, and bends a peripheral edge portion of the pl-epared hole
of the first wall portion to the outside of the first wall portion to form the burring hole;
and
- a second-b~u~~~imgpuwnhcihc l~h as the first axis Iine as the center axis line
along with the second piercing punch, and balds a peripheral edge poi-tion of the
prepared hole of tlle seco~~wdaI 1 portion to the outside of the second wall portion to
form the burri11g hole.
18. The burring appal-atus accordiilg b Clairn 17,
wl~ereinth e firs[ external unit further includes:
a first burring holder which has the first forn~ingh ole into which the first
burring punch is inserted, and is provided so as to be movable along the first axis line
outside the first wall portion in a state where a center axis line of the first forming hole
coincides with the first axis Iine; and
a frst piercing die which has the first thougl'i hole serving as a passage of the
first piercing punch and is provided so as to be movable along the first axis line outside
the first wall portion in a state whe1.e a center axis line of the first through hole
coincides with the first axis line inside the first forming hole of the first burring die,
wherein the first piercing punch is provided so as to be movable between the
outside and the inside of the first wall portion along the f i l ~atx is line inside the first
though hole of the first piercing holder in a state where a center axis line of the first
piercing punch coincides with the first axis line,
wherein the second external unit further includes:
a second burring die which has the second forming hole into which the second
burring punch is inserted, and is provided so as to be movable along the Grsi axis line
outside the second wall pol-tioo in a state where a center axis line of the second
forming hole coincides with the first axis line; and
a second piercing holder which has the second through hole serving as a
passage of the second piercing princh and is provided so as to be movable aIong the
first axis line outside the second wall porliorl in a state where a cerlter axis line of the
second tllrough hole coincides with the first axis line inside the secbnd forming hole of
the second burring die,
wherein the second piercing puncll is provided so as to be ~~~ovabbeltwe eep
the outside and the inside of the second wall portion along the first axis line inside the
second though hole of the second piercing holder in a state where a center axis Iine of
the seco~~pdie rcing punch coi~lcidesw ith the first axis line,
wherein the internd uiiit further iiicfudes a tubular llousirlg which includes the
first burring punch and the second burring punch and has both opened end surfaces,
wherein the housing is configured such that one end surface of the housing
comes into surface contact with an inner wall surface of the first wall portion and the
other end surface of the housing comes into surface contact with at1 inner wall surface
of the second wall portion,
wherein the firs[ burring punch includes a first piercing hole into which the
first pierchg punch is inserted, and Is provided so as to be movable between the
outside and the inside of the first wall portion atong the first axis Iine inside the
housing in a state where a center axis line of the first piercing hole coincides with the
first axis line, and
wherein the second burring punch includes a second piercing hole into which
the second piercing punch is inserted, and is provided so as to be movabIe between the
outside and the inside of the second wall portion along the first axis Iine inside the
housing in a state where a center axis tine of the second piercing hole coincides with
the first axis line.
19. The but~inga pparatus according to Claim 18,
wherein in a case where a center position between the first walI portion and
the second d por-tion.on the first axis Ijne is defined as a reference point,
the first burring punch and the second burring punch are disposed so as to face
each other in a state where the refereizce point Is interposed therebetween;
the internal unit further includes a stopper rvl~ichp asses through the reference
point and is provided so as to be movable along a second axis Iine orthogonal to the
first axis line; and
the stopper has a shape which causes the first burring puncl~to move to the
outside of the first wall portion and the second burring punch to move to the outside of
the second wall po~tioriln a pxoccss in which the stopper passes th1.011gl the reference
point along tbe second axis Iine.
20. The buring apparatus according to Clairn 19,
wherein the internal unit further includes a barring punch return ~rnecf~auism
which sepat-ately applies an external force toward the reference point to each of the
first burring punch and the second burring punch.
21. The buwing apparatus according to Claim 18,
wherein each of the fitxt piercing hole of the first burring punch and the
second piercing hole of the second burring punch includes a bottom portion,
wherein in a case where a center position between the first wall portion and
the second wall portion on the first axis line is defined as a reference point,
the first burring punch and the second burring punch are disposed so as to face
each other in a state where the reference point is interposed there between;
the ititelurn1 unit further includes a stopper which passes thugh the reference
point and is provided so as to be movable almg a second axis Iine olthogonal to the
first axis line; 5
the stopper has a shape ~vliichc auses the first burring grulch to move toward
the first wall pol-iion and the second burring punch to move toward the second waI1
poltion in a process in which the stopper passes t h u g h the reference point along the
second axis line; and
the stopper includes a separation block which is separated from the stopper
when the stopper stops it1 a state where the first burring punch comes into pressure
corltact with an inner waIl surface of the first wall portion and the second burring
punch comes into pressure contact with an inner wall surface of the second wall
portion, and which is movable inside the housing along the first axis line along with
the firsst burring punch md the second burring punch.
22. The burring apparatus according to Claim 12,
wherein the first external ur~itin cludes:
n fust piercing punch ivllich forms a prepared hole on the first waIL poaion;
and
a first burring puncll which has the first axis line as the center axis Iine along
with the first piercing punch, and bends a peripheral edge portion of the prepared hole
of the first wall portion to the inside of the first wall portion to form the burring hole,
and
wherein the internal unit includes:
a secoild piercing punch which forms a prepared hole on the second wall
portion; and
a second bluwing punch which has the first axis line as the center axis line
along with the second piercing punch, and bends a peripheral edge portion of the
. prepared hole of the second wall portion to the outside of the second wall por-tion to
form the- burring hole.
23. The burring apparatus according to Claim 22,
wherein the first.exterua1 unit fi~rtheirn cludes a first bur~i~hlgo lder which has
a first through hole serving as a passage of the first burring punch and is provided so as
to be movable outside the first cvall portion in a state lv11el.e a center axis line of the
first though hole coincides with the first axis line,
wherein the first buning punch is provided so as to be mnovabIe aIong the first
axis line inside the first througll hole of the first burring holder in a state where a center
axis line of the first burring punch coincides with the first axis line,
wlle~~tihne first piercing punch is attached to a front end of the first burring
putlch ivhi le having the first axis line as the center axis line along with the first bul~ing
pmch,
wherein the internal unit further includes:
a first burring die which has a first forming hole into which the first burring
punch is inseried, and is provided so as to be movable along the first axis line in a state
where a center axis line of the first forming hole coincides with the first axis line;
a first piercing die which has a first piercing hole into which the first piercing
punch is inserted, and is provided so as to be movable along the first axis line inside
the first forming hole of the first burring die in a state whete a center axis line of the
first piercing hole coi~lcidesw ith the first axis line; and
a second burring holder which has a second though hole serving as a passage
of the second bui.Hlg PULIC~; and is provided so as to be movable along the first axis
line in a state where a center axis line of the second through hole coincides wit11 the
first axis line,
wherein the second burring ptmch is provided so as to be t~zovablea long the
first axis line inside the seco~ldth rough hole of the second burring holder iia a state
where a center axis line of the second burring punch coincides with the first axis line,
wherein the second piercing punch is attached to a front erld of the secorld
burring punch while having tile first axis line as the center axis line along with the
second burring punc11, and
wherein the second external unit includes:
a second burring die which bas a seco~idf o~mingIm lc into which the second
burring punch is inserted, and is plavided so as to be movable outside the second wall
portion along the first axis line in a state where a center axis line of the second-fo~ming
hole coi~zcidews it11 the first axis Iine; and
a second piercing die which has a second piercing hole into which the second
piercing punch is inserted, and is provided so as to be movable outside the second wall
poltiotl along the first axis 1 ine in a state where a center axis Iine of the second piercing
hole coincides with the first axis line inside the second forming hole of the second
burring die.
24. The burrir~ga pparatus acco~dingto Claim 23,
wherein the first piercing hole of the first piercing die includes a bottom
portion,
wherein in a case where a center position between the first wall portion and
the second wall portion on the first axis line is defined as a reference point,
the.firsr burring die and the second burring holder are disposed so as to face
each other in a state where. the reference point is interposed therebetween;
the first pierciizg die and the second bur~ingp unch are disposed so as to face
each other in a state \vhere the reference point is interposed tflerebehveen;
the internal unit further includes a stopper which passes fhl-ough the reference
point and is provided so as to be movable along a second axis line orthogonal to the
first axis line; . ,
the stopper lias a shape .~vlliccl~au ses the first 171irri11g die and the first pie~cing
die to move toward the first wall portibn a d the second brrning holder and the second
burrirrg punch to move toward the second wall portior~i n a process in ivhictl fhe
stopper passes through the referw~cep bht along the sccond axis line; and
tI1c stopper: illclrtdes a separation block which is separated from the stopper
rvlien the stopper stops in a state where the first burring die and the first piercing die
come illto p1Essure coniact wit11 an inner w ds rriface of the fust wall poxfio~la, nd the
second pi erciug plrnch attached to fimt ends of the sec&d burring holder and the
secorzd btming ~~uncclolm e illto pressure contact ivif h an hmer wall surface of (he
secorld wali portion, siud ~vliclils movable along the first axis line along with the first
piercing die and the second burrhg puncl~.
25. The burring apparatus according to Clai~n2 4,
whel~inth e j ntenlal ut it fi~rthcri i nclt~deas die I + ~ ~ I T I I I mecl~a~isrrnvl licfl
appl ics an external force toward tllc 1-efere~icpe oint to the fus t bul~ingd ie,