Description
Title of Invention
MANUFACTURING APPARATUS AND MANUFACTURING METHOD FOR
5 STRETCH-FORMED PRODUCT
Tecluiical Field
[OOOl]
The present invention relates to a manufacturing apparahls and a
10 nianufachlring method for a stretch-formed product. Specifically, the present
inventioti relates to a manufacturing apparatus and a manufacturing method for a
stretch-formed product obtaiued by stretching a blank between a punch and a die in a
state of clamping a margin of the blank by the die and a blank holder such that the
blank does not flow into a forniing region.
15
Background Art
[0002]
In general, press-for~iiitigo f thin plates is roughly classified into the thee of
bending forniing, stretch forming and draiving. The bending forming is a method of
20 "fok~nirigt he blarik'by EEnding it by using the die and tlie punch without clamping the
margin of the blank. In contrast thereto, the stretch forming and the drawing are
tilethods of forming tlie blank by pressing the punch against a forniing region located
at the center of the blank in a state of clamping the margin of tlie blank by the die and
the blank holder.
25 [0003]
FIG. 13 is an explanato~yd iagram sho\vitig tlie stretch forming. As sliow~~n
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in FIG. 13, in the stretch forming, a punch 4 is relatively pressed into a die 2 in a
state of clamping mainly a clamp target part la provided on a margin of a blank 1 by
trapezoidal beads 2a and 3a as one form of lock beads which are provided odin the
die 2 and a blank holder 3. Accordingly, a stretch-fornled product is forllled by
5 stretching the blank 1 such that the margin of the blank 1 does not substantially flow
(move) toward a forming region lb of the blank 1, which col.l.espouds to a product
part. It is general that, for example, in automobile components, large-sized
co~nponet~htasv ing comparatively simple shapes such as a door outer panel, a hood
outer panel, and a roof panel are manufactured by the stretch forming.
10 [0004]
In contrast thereto, in the drawing, the punch is relatively pressed into the
die in a state of clamping mainly the clamp target part provided on the margin of the
blank by draw beads which are provided onlin the die and the blank holder. In the
drawing, the amount of the blank which flows from the margin of the blank toward
15 the forming region of the blank which corresponds to the product part is properly
controlled per component by the draw beads during forming. Thereby, formability
is controlled such that cracks, wrinkles and so forth are not generated in1011 the
product. It is general that a component which has a cotnparatively complicated
shape, such as, for example, a side panel outer in the automobile components is
20 manufactured by the drawing.
[OOOS]
Both of the lock beads used in the stretch forming and the draw beads used
in the drawing are the ones for adjusting a tensile force to be loaded on the blank
such that shape defects such as the cracks and xvrinkles and excessive surface
25 deflection are not generated in the fornling region (the product pal-t) of the blank like
this. However, while the stretch forming is the one for causing the blank not to
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flow from the margin of the blank into the forming region, tlie drawing is the one for
causing the blank to flow from the tiiargin of tlie blank into the forming region.
Accordingly, the lock beads used in the stretch forming are different from the draw
beads used in the drawing for controlling tlie inflow of tlie blank in the point that
5 flowing of the blank from the margin of the blank into tlie for~ning region is
substalitially eliminated.
[0006]
Hitherto, as the beads whicli are provided inlon the die and the blank holder
and cla~iip the blank margin in order to eliminate flowing of the blank into the
10 forming region, such trapezoidal beads as shown in FIG. 13 are generally known.
The trapezoidal beads are substantially trapezoidal in section and clamp the blank 1
such that the blank 1 does not flow into it by deforniation resistance of bending and
unbending deformation of a trapezoidal corner part and frictional resistance caused
by contact of the beads 2a and 3a each provided inJon the die 2 and the blank holder
15 3 with the blank 1.
[0007]
FIG. 14 is an explat1ato1-y diagram showing one example of the blank 1
which has the claiilp target part la to be clarnped by tlie beads and the forniing region
lb corresponding to the product part (a rear outer panel) of the blank 1 and is used in
20 the stretch forming. FIG. 14 is the exaniple of tlie blank 1 in a case of
manufacturing two rear door outer panels from one blank 1.
[OOOS]
As exemplified in FIG. 14, an outer peripheral part lc of the clamp target
part la of the blank 1 is cut off along a trim line id and is cut down together with the
25 clatnp target part la. Accordingly, if tlie outer peripheral part lc and the clanip
target part la can be set as s~iiall as possible after having ensured a blank clamping
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force wliicli is required for the stretch forming, the entire size of the blank 1 will
beco~ne small as much. Thereby, the material yield in the stretch forming is
improved. In particulal; since the stretch forming is used for forming the
comparatively large-sized conlponcnts as described above, an effect of reducing
5 amount of used amount of material, that is, of improving the material yield owing to
miniaturization of the blank 1 is large.
[0009]
FIG. 15 to FIG. 17 are explanatory diagrams showing states of the vicinity
of the trapezoidal bead 2a in a case of performing the stretch forming by using a die
10 having the general trapezoidal beads 2a and 3a. FIG. 15 is perspective vie\vs
showing the states before and after clamping the blank 1 by the die 2 and the blank
liolder 3. FIG. 16 is a sectional view showing the vicinity of the trapezoidal beads
2a and 3a including the clamp target part la, the outer peripheral part lc and the trim
line id of the blank 1. FIG. 17 is a top view showing the vicinity of the trapezoidal
15 beads 2a and 3a including the clamp target part la, the outer peripheral part lc and
the trim line id of the blank 1. Incidentally, in FIG. 15 to FIG. 17, althougl~ a
boundary between the inside and outside of the product is shown by a broken line, a
region of a length L1 is a bead corresponding part of the blank 1 to be clamped by
the beads 2a and 3a and is a pai-t to be generally discarded.
20 [OOlO]
The trapezoidal beads 2a and 3a are adapted to obtain a blank clamping
force which is sufficient for the stretch forming by causing the bending and
unbending defonnatiori resistance of four trapezoidal corner parts 2a-1, 2a-2, 3a-1,
and 3a-2 to generate. In mass forming, it is necessary to make the length of a
25 sectional straight side part 2a-3 long to some extent in order not to destroy the
trapezoidal bead 2a and in order to cause the bending and unbending deformation
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resistance of tlie trapezoidal corner parts 2a-1 and 2a-2 to be generated indepe~identlp
in the respective corner parts. Accordingly, the pressing length L1 of the
trapezoidal beads 2a and 3a in a direction orthogonal to the tritn line id beconies
inevitably long. Therefore, it is difficult to sliorten the pressing length L1 and to
5 miniaturize the blank 1 with the trapezoidal beads 2a and 3a.
[OOll]
In Patent Literature 1, there is disclosed a drawing method of, in a drawing
apparatus which is provided with a die, a punch and a blank holder, drawing a
material in a state of holding the material by the blank holder and a facing die in
10 which draw beads having continuous bead parts that are non-parallel to a line parallel
to a drawing profile of the material are formed on wxinkle pressing surfaces.
[0012]
In Patent Literature 2, there is disclosed a drawing method of, in a drawing
apparatus wl~ich is provided with a die, a punch and a blank holder, providing a
15 movable die face which configures a die face part and is movable relative to a die
body and a movable blank holder which faces the movable die face and is movable
relative to a blank holder body, making the movable die face and the movable blank
holder fieely advance and retreat fro111 the outside to tlie inside toward a forming
depressed part in the die, driving the movable die face and tlie movable blank holder
20 from the outside to the inside in association with pushing of the blank and thereby
perfor~ilingd rawing in high yield such that a shock line does not enter a product part.
[0013]
111 Patent Literature 3, there is disclosed a press die device wliicli perfonns
drawing and stretching by forming a bead on one die and for~ninga bead co~ltaitiing
25 part for containing tlie bead in a part facing the bead on another die, n~liereia step
parts individual protruding heights of which are gradually reduced laterally are
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provided on a leadirlg end of the bead, stepped depressed parts which corresporld to
the step parts are provided in the bead containing part, unevenness which
cot+espot~dsto the step parts in a case wliere a blank material is nipped and held
between the both is formed on an edge of tlic blank material and thereby generation
5 of wrinkles can be prevented even in a case of being applied to a press ~llachi~le
having a low load capacity.
[0014]
In Patent Literature 4, there is disclosed a bead to be provided on a wri~lkle
pressing surface of a draw die, the draw bead being configured by a vertical wall part
10 aud a corrugated part which is formed to be consecutive to the vertical wall part and
is corrugated in section.
Citation List
Patent Literature
15 [0015]
Patent Literature 1: JP H9-29348A
Patent Literature 2: JP H9-225552A
Patent Literature 3: JP 138-267154A
Patent Literature 4: JP 2007-245 188A
Su~luna~oyf Invention
Technical Problem
[0016]
The method described in Patent Literature I is the one which intends to lock
25 the material such that the material does not flow from the outside of the bead into the
inside of the bead by using the beads which are trapezoidal in section and are
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corrugated in top view. In that method described in Patent Literature 1, the blank is
clamped with the deformation resistance of bending and u~lbe~lditldge formation of
the trapezoidal corner part, a surface pressure of the bead relative to the blank and
expansio~l/contraction dcfor~llation resistance according to the corrugated shape.
5 The method described in Patent Literature 1 may increase bead passing resistance of
the material by extending the material up to a region outside a part which is clamped
by the bead. Accordit~gly, the method described in Patent Literatt~re 1 cannot
improve the material yield due to an increase in parts n~hicha re cut off along the
drawing profile and discarded.
10 [0017]
The method described in Patent Literature 2 is the one which targets on
drawing which involves flowing of the material although aiming to improve the yield
of material. Accordingly, the method described in Patent Literature 2 cannot
improve the yield of material in the stretch forming which does not involve flowing
15 of the material.
[0018]
The method described in Patent Literature 3 camlot improve the yield of
material in the stretch forming because the bead length in the direction which is
orthogonal to the material flowing direction is inevitably increased.
20 [0019] '
Although the draw bead described in Patent Literature 4 is the bead which
aims to improve the yield of steel material by suppressing flowing-in of the material,
it purpol-ts a draw bead to be used in the drawing. Accordingly, the draw bead
described in Patent Literature 4 is not the one which improves the yield of material
25 by preventing flowing-in of the material in lock beads to be used in the stretch
forming.
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[0020]
The present invention has been made in view of the above mentioned
problems and an object of the present invention is to provide a manufacturing
apparatus and a manufacturing method for a stretch-fornled product which can
5 improve the yield of material in the stretch forming performed while clamping the
blank by the lock beads.
Solution to Problem
[0021]
10 To solve the problem, according to an aspect of the present invention, there
is provided a manufacturing apparatus for a stretch-formed product, the
manufacturing apparatus including: a die and a blank holder which have clamping
surfaces facing each other; a punch that, in a state where a margin of a blank of a
sleet material is clamped by the clamping surfaces of the die and the blank holdel;
15 relatively presses a forming region of the blank into the die and thereby performs
stretch forming on the fonning region of the blank; and lock beads that are provided
on the clamping surfaces of the die and the blank holder in mutually similar shapes
and have first surfaces, second surfaces that intersect with tlie first surfaces, and third
surfaces that intersect with the second surfaces from outer edges toward the centers
20 of the die and the blank holdel; the first surfaces each having a plurality of
depression-protrusio~ip arts.
roo221
When the plurality of depression-protrusion parts are viewed from the outer
edge toward tlie center of the die or the blank holdel; the plurality of depression-
25 protrusion parts may have any shape of a trapezoidal shape, a rectangular shape and a
triangular shape or a combined shape thereof.
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[0023]
The plurality of depression-protrusion parts may each have a foul-tl~s urface
and a fifth surface intersecting with each other, the fourth surface and the fifth
surface may intersect with the second surface, and at least one of the fourth surface
5 and the fifth surface may intersect with the first surface.
[0024]
The plurality of depression-protrusion parts may each have the fourth
surface and a sixth surface facing each other and the fifth surface that intersects with
the fourth surface and the sixth surface, the fourth surface, the fifth surface and the
10 sixth surface may intersect with the second surface, and at least one of the fourth
surface, the fifth snrfaee and the sixth surface may intersect with the first surface.
[0025]
In a ease where the plurality of depression-protrusion parts each have the
triangular shape, a pitch interval of the plurality of depression-protrusion parts when
15 the triangular shape is defined as one pitch may be w i t h a range of 5 to 50 nnn, and
a rising angle of a surface of the depression-protrusion part may be within a range of
10 to 40 degrees.
[0026]
In a ease where the plurality of depression-protrusion parts each have the
20 trapezoidal shape or the rectangular shape, a pitch interval of the plurality of
depression-protrusion parts when a set of a protruded shape and a depressed shape is
defined as one pitch may be within a range of 5 to 50 rnnl and a height of the
depression-proti-usion part may be within a range of 1.0 to 10.0 mnl.
[0027]
25 In addition, in order to solve the above-nlentioned problems, according to
another aspect of the present invention, there is provided a lnanufacturing method for
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a stretch-formed product, the method including a step of clampiug a margin of a
blank of a sheet material by the clamping surfaces of the die and the blank holder
which are provided with lock beads which have first surfaces, second surfaces which
intersect with the first surfaces and third surfaces which i~lterscctw ith the second
5 surfaces from outer edges toward the centers of the die and the blank holder at
positions correspotlding to the margin of the blank of the sheet material, the first
surfaces each having a plurality of depression-protrusion parts, and the lock beads
being provided in mutually similar shapes, and a step of stretch-forming the blank by
pressing a fonning region of the blank toward the die by a punch in a state of
10 clamping the margin of the blank by the die and the blank holder.
Advantageous Effects of Invention
[0028]
According to the present invention, the yield of material in the stretch
15 forming performed while clamping the bla~lkb y the lock beads can be improved.
Brief Description of Drawings
[FIG. 11 FIG. 1 is a perspective view for explaining a configuration of a
20 manufacturing apparatus for a stretch-formed product according to at1 embodiment of
the present inve~ltion.
[FIG. 21 FIG. 2 is a perspective view showing states before and after
clamping a blank by lock beads according to the embodiment.
[FIG. 31 FIG. 3 is a sectional view showing the lock beads, an outer
25 peripheral part of the blank and a trim line.
[FIG. 41 FIG. 4 is a top view showing the lock beads, the outer peripheral
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part of the blank and the trim line.
[FIG. 51 FIG. 5 is a perspective view showing states before and after
clamping the blank by other lock beads.
[FIG. 61 FIG. 6 is a sectional view showing the other lock beads, the outer
5 peripheral part of the blank and the trim line.
[FIG. 71 FIG. 7 is a top view sho\ving the other lock beads, the outer
peripheral part of the blank and the trim litle.
[FIG. 81 FIG. 8 is an explanatory diagram showing a test procedure of an
Evaluation I in an Example.
10 [FIG. 91 FIG. 9 is a graph showing a result of the Evaluation 1 in the
Example.
[FIG. 101 FIG. 10 is photographs for explaining a difference in blank
flowing mark due to a difference in decision on lock perfornlance.
[FIG. 111 FIG. 11 is a front view showing an outline shape of a blank of a
15 stretch-formed product manufactured though an Evaluation 3 in the Example.
[FIG. 121 FIG. 12 is a perspective view showing a dinlension of each part of
the stretch-fornled product tnanufactured through the Evaluation 3 in the Example.
[FIG. 131 FIG. 13 is an explanatory diagram showing a state of stretch
forming.
20 [FIG. 141 FIG. 14 is an explanatory diagram showing one example of the
blank used in the stretch for~ning.
[FIG. 151 FIG. 15 is a perspective view showing states before and after
clamping the blank in the stretch fornling using a die provided with conventional
trapezoidal beads.
25 [FIG. 161 FIG. 16 is a sectional view showing the vicinity of the
conventional trapezoidal beads.
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[FIG. 171 FIG. 17 is a top view showing the vicinity of the conventiot~al
trapezoidal beads.
Description of Embodiments
5 [0030]
Hereinafter, (a) preferred embodiment(s) of the present invention will be
described in detail with reference to the appended drawings. In this specification
and the appended drawings, structural elements that have substantially the same
function and structure are denoted with the same reference numerals, and repeated
10 explanation of these structural elements is omitted. Although in the following
description, description will be made by taking a case where the stretch-formed
product is a door outer panel by way of example, the stretch-formed product is not
limited to the door outer panel. The present invention is equally applied also to
other stretch-formed products such as a hood outer panel and a roof panel.
15 [0031]
i l . Manufacturing Apparatus for Stretch-Formed Product>
FIG. 1 is a schematic explariatory diagram showing a configuration of a
manufacturing apparatus 10 for a stretch-formed product according to the present
embodiment. FIG. 1 is a perspective view showing tlie manufacturing apparatus 10
20 by partially omitting and simplifying it. As shown in FIG. 1, the manufacturing
apparatus 10 has a die 11, a blank holder 12, and a punch 13. In FIG. 1, tlie contour
of a blank 14 is shown by a two-dot chau~li ne.
[0032]
(1 - 1. Basic Configuration)
25 The die 11 has a clamping surface l l a which clamps the blank 14. The
clamping surface l l a has a pu~iclic o~itainillgp art in wliicll the punch 13 is to be
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contained when forming, and a wedge-shaped bead 15 \vhich is provided along the
outside of a margin of the blank 14. The wedge-shaped bead 15 is one form of the
lock bead. In order to make the drawing easily visible, in FIG. 1 , the die 11 and the
wedge-shaped bead 15 are shown by being simplified by a one-dot chain line.
6 Details of the wedge-shaped bead 15 will be described later with reference to FIG. 2.
In addition, the punch containing part is omitted in FIG. 1.
[0033]
The blank 14 is located at the center and has a forming region 14b
corresponding to a past which will become a product (in the example in FIG. 1, a rear
10 door outer panel), a clamp target part 14a to be clamped by the die 11 and the blank
holder 12 and a trim line 14d. The clamp target part 14a and the outer peripheral
part 14c are cut off along the trim line 14d and are discarded. Incidentally, in FIG.
1, the trim line 14d is omitted.
[0034]
15 The wedge-shaped bead 15 may be arranged on the entire circumference of
the blank 14. Alternatively, in a case where a part to be subjected to drawing which
involves material flowing-in and a part to be subjected to stretch forming ~vhichd oes
not involve material flowing-in are present on the blank 14, the wedge-shaped bead
15 may be arranged only on the part to be subjected to the stretch forming. In this
20 case, various tyfies of known draw beads for the drawing can be provided on the part
to be subjected to the drawing.
[0035]
The blank holder 12 is auanged so as to face the die 1 1 . The blank holder
12 has the punch containing part in which the punch 13 is contained, and the
26 clamping surface 12a which clamps the blank 14 in cooperation with the cla~nping
surface lla of the die 11. A wedge-shaped bead 16 is provided on the clamping
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surface 12a along the ~nargio~f ~th e blank 14. The wedge-shaped bead 16 is
arranged at a positio~c~o rresponding to the wedge-shaped bead 15 provided on the
die 11. Details of the wedge-shaped bead 16 will be described later with reference
to FIG. 2.
5 [0036]
The punch 13 is arranged in the pu11c11 co~~tainip~alrgt of the blank holder
12 so as to face the punch containing part of the die 11. The punch 13 is relatively
pressed into the die 11 at the time of forming. Thereby, the forming region 14b of
the blank 14 is stretch-formed and the forming region 14b is formed into the door
10 outer panel.
[0037]
Since the materials and functions of the die 11, the blank holder 12 and the
punch 13 may be the same as the materials and functio~~wsh ich are known as those
of dies, blank holders and punches of this type, and are well known to a person
15 skilled in the art, further description on the die 11, the blank holder 12 and the punch
13 is omitted.
[0038]
(1-2. Lock Bead (Wedge-Shaped Bead))
The wedge-shaped bead 15 to be provided on the die 11 and the wedge-
20 shaped bead 16 to be provided on the blank holder 12 are provided so as to mutually
correspond to each other in positiou and shape. When forming, the clamp target
part 14a of the blank 14 is nipped and held, aud cla~npedb y the wedge-shaped beads
15 and 16 such that the blank 14 does uot flow iuto the forming region 14b.
[0039]
25 FIG. 2 to FIG. 4 are explanatory diagrams showing the states of the wedgeshaped
beads 15 and 16 at the time of stretch forming. FIG. 2 is a perspective view
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showing the states before atid after clamping the blank 14. FIG. 3 is a sectiotlal
view showing tlie wedge-shaped beads 15 and 16, and the outer peripheral part 14c
and tlie trim line 14d of the blatk 14. FIG. 4 is a top view showing the wedgeshaped
bead 15, and the outer peripheral part 14c and the trim line 14d of the blank
5 14. Aregion of the length L1 is a part to be clamped by the wedge-shaped beads 15
and 16 and to be discarded in most cases.
[0040]
Incidentally, in the following description, the wedge-shaped bead 15
'provided on the die 11 will be mainly described. Sitlee tlie wedge-shaped bead 16
10 provided on the blank holder 12 corresponds to the wedge-shaped bead 15 in position
and shape, it can be understood by reading it through appropriate alteration.
[0041]
As shown in FIG. 2 and FIG. 3, the wedge-shaped bead 15 has a stepped
shape including a first surface 15-1, a second surface 15-2 and a third surface 15-3
15 from the outer edge toward the center of tlie die 11 (from the left side to tlie right side
in FIG. 3). That is, the first surface 15-1, the secorid surface 15-2 and tlie third
surface 15-3 make a step fsom the outer edges toward the centers of the blatk holder
12 and the die 11. The second surface 15-2 intersects with (in tlie shown example,
is orthogonal to) the first surface 15-1. The third surface 15-3 intersects witli (in the
20 shown example, is orthogo~iatlo ) the second surface 15-2.
[0042]
As shown in FIG. 2 and FIG. 4, the first surface 15-1 of tlie wedge-shaped
bead 15 has a plurality of depression-prott~~siopna rts each configured by a fourth
surface 15-4, a fifth surface 15-5 and a sixth surface 15-6. The fifth surface 15-5
25 intersects witli the fourth surface 15-4. The sixth surface 15-6 intersects with the
fifth surface 15-5 atid faces the fourth surface 15-4. That is, the fourth surface 15-4
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and tlie sixth surface 15-6 face each other,
[0043]
The fourth surface 15-4, tlie fifth surface 15-5 and the sixth surface 15-6 are
continuously formed in order of the foul-tb surface 15-4, the fifth surface 15-5, the
5 sixth surface 15-6 and the fifth surface 15-5 in an extending direction of the wedgeshaped
bead 15, that is in tlie direction orthogonal to a direction going from tlie outer
edge toward the center of the die 11. Thereby, depressed and prot~~~dsheadp es are
alternately arrayed on the first surface 15-1 in the extending direction of the wedgeshaped
bead 15. In a section parallel to the second surface 15-2, the fourth surface
10 15-4, the fifth surface 15-5 aud the sixth surface 15-6 of the wedge-shaped bead 15
form three sides of a substantial quadrilateral. Although they make three sides of a
trapezoid in the sliown example, they may make three sides of a rectangle.
[0044]
The height and pitch of this quadrilateral, the rising angles of the fourth
15 surface 15-4 and the sixth surface 15-6, and the radius of curvature of a corner part
that the fourth surface 15-4 or the sixth surface 15-6 and the fifth surface 15-5 make
call be appropriately set. However, when the height of the quadrilateral is too low
or the pitch is too large, it becomes difficult to obtain aa effect of increasing the
deformation resistauce (hereinafter, also referred to as the "unbending deformation
20 resistance") caused when the depressed and protruded shapes are unbent to planar
shapes, and the blank clampit~gf orce is lowered in some cases. Meanwhile, when
the height of the quadrilateral is too high, it is feared that the blank 14 may be
destroyed \vhen clamping the blank 14. Meanwliile, when the rising angles of the
fourth surface 15-4 and the sixth surface 15-6 are too small, it becomes difficult to
25 obtain the effect of increasing the unbending deformation resistance, and the blank
clamping force is lowered in some cases.
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By taking these points into consideration, in a case where the wedge-shaped
bead 15 having a quadrilateral wedge shape (a trapezoidal one and a rectangular one
are included) is to be fonned, it is preferable that an illtellrat per pitch that a
5 protruded sliape and adepressed shape of the quadrilateral are defined as one set be
within a range of 5 to 50 mm and the height of the quadrilateral be within a range of
1.0 to 10.0 mm. Incidentally, the pitch interval in a case of the trapezoidal wedge
shape and so forth means a pitch interval when a set of the protruded shape and the
depressed shape of the trapezoid is defined as one pitch wit11 a position where the
10 height of the trapezoid is 112 being set as a reference.
[0046]
111 addition, \vhen in relation to the height of the secoud surface 15-2, a level
difference between the third surface 15-3 and the fifth surface 15-5 is too small,
bending defornlation of the blank 14 on the depression-protrusion part and bending
15 deformation at the boundary between the second surface 15-2 and the third surface
15-3 callnot be individually generated and it is feared that the effect of increasit~gth e
unbending deformation resistance may not be obtained. In addition, when the level
difference is too large, it is feared that the material yield of the blank 14 may be
lowered. Accordingly, it is preferable that the level difference be nithit1 a range of
20 1.5 to 8.0 mm.
[0047]
A fourth surface 16-4, a fifth surface 16-5 and a sixth surface 16-6 of the
wedge-shaped bead 16 provided on the blank holder 12 are arranged at positions
respectively corresponding to the fourth surface 15-4, the fifth surface 15-5 and the
25 sixth surface 15-6 of the wedge-shaped bead 15 provided on the die 11.
Accordingly, in a state of clamping the blank 14 by the die 11 and the blank holder
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12, the fourth surface 15-4, the fifth surface 15-5 and the sixth surface 15-6 of the
wedge-shaped bead 15 respectively face the fot~rths urface 16-4, the fifth surface 16-
5 and the sixth surface 16-6 of the wedge-shaped bead 16 via the blank 14.
[0048]
5 Incidentally, although in the above description, a case where the wedgeshaped
bead 15, 16 has a stepped shape in which the first surface 15-1, 16-1 is
located lower than the third surface 15-3, 16-3 has been taken by way of example,
the stepped shape may be reversed. That is, the wedge-shaped bead 15, 16 may
have a stepped shape in which the first surface 15-1, 16-1 is located higher than the
10 third surface 15-3, 16-3.
[0049]
(1-3. Modified Exanlples of Lock Bead (Wedge-Shaped Bead))
FIG. 5 to FIG. 7 are explanatory diagrams showing other wedge-shaped
beads 17 and 18 used in the stretch forming as a modified example of the lock bead.
15 FIG. 5 is a perspective view showing the states before and after clamping the blank
14. FIG. 6 is a sectional view showing the wedge-shaped beads 17 and 18, and the
outer peripheral part 14c and the trirn line 14d of the blank 14. FIG. 7 is a top view
showing the wedge-shaped bead 17, and the outer peripheral par1 14c and the trim
line 14d of the bla~lk 14. A region of the length L1 is a part to be clanlped by the
20 wedge-shaped beads 17 and 18 and to be discarded in most cases.
[OOSO]
Incidentally, similarly to the above description, the wedge-shaped bead 17
provided on the die 11 will be mainly described later. Since the wedge-shaped bead
I8 provided on the blank holder 12 also corresponds to the wedge-shaped bead 17 in
26 position and shape in this example, it can be understood by reading it through
appropriate alteration.
PCT/JP2014/082GG4
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19
[0051]
As shown in FIG. 5 and FIG. 6, the wedge-shaped bead 17 has a stepped
shape including a first surface 17-1, a second surface 17-2 and a third surface 17-3
frotll the outer edge toward the center of the die I I (from the left side to the right side
5 in FIG. 6). That is, the first surface 17-1, the second surface 17-2 and the third
surface 17-3 make a step from the outer edges toward the centers of the blank holder
12 and the die 11. The second surface 17-2 intersects with (in the shown example,
is orthogonal to) the first surface 17-1. The third surface 17-3 intersects with (in the
sI1o\vn example, is ortl~ogonatlo ) the second surface 17-2.
10 [0052]
As shown in FIG. 5 and FIG. 7, the first surface 17-1 of the wedge-shaped
bead 17 has a plurality of depression-protrusion parts in which a fourth surface 17-4
and a fifth surface 17-5 are alternately and continuously formed in an extending
direction of the wedge-shaped bead 17, that is in the direction orthogonal to the
15 direction going from the outer edge toward the center of the die 11. Thereby,
depressed and protruded shapes are alternately arrayed on the first surface 17-1 in the
extending direction of the wedge-shaped bead 17. I11 a section parallel to the
second surface 17-2, the fou~tslu~rf ace 17-4 and the fifth surface 17-5 of the wedgeshaped
bead 17 fort11 two sides of a triangle.
20 [0053]
The height and pitch of this triangle, the rising angles of the fourth surface
17-4 and the fifth surface 17-5, and the radius of curvature of a corner part that the
fourth surface 17-4 and the fifth surface 17-5 make can be appropriately set.
However, when the height of the triangle is too low or the pitch is too large, it
25 beconles difficult to obtain the effect of increasing the unbending deformation
resistance, and the blank cla~nping force is lowered in some cases. Meanwhile,
PCTIJP2014/082664
Our Ref.: NNSC14045-IN
20
when the rising angles of the fourth surface 17-4 and the fifth surface 17-5 arc too
small, the pitch of the triangle beconlcs large, and conseq~tentlyit becomes difficult
to obtain the effect of increasing the unbending deformation resistance and the black
clampitig force is lowvercd in some cases. Mean\vhile, \vhctl the rising angles of the
5 fourth surface 17-4 and the fifth surface 17-5 are large and tlie height of the triangle
becomes too high, it is feared that the blank 14 may be destroyed ~vhenc lamping the
blank 14 and wrinkles may be generated on the blank 14.
[0054]
By taking these points into co~isideratioti,i n a case where the wedge-shaped
10 bead 17 having a triangular wedge shape is to be formed, it is preferable that a pitch
interval of the triangle be within a range of 5 to 50 mm and the rising angles of the
fourth surface 17-4 and the fifth surface 17-5 be within a range of 10 to 40 degrees.
Incidentally, the pitch interval in a case of the triangular wedge shape means the
length of tlie base of the triangle.
In addition, when in relation to the height of the second surface 17-2, a level
difference betweeti the third surface 17-3 and the apex of the triangle is too small,
bending defor~nation of the blank 14 on the depression-protrusion part and bending
deformation at the boundary between the second surface 17-2 and the third surface
20 17-3 carmot be individually generated and it is feared that the effect of increasing the
unbending deforn~ationr esistance may not be obtained. In addition, when the level
difference is too large, it is feared that the material yield of the blank 14 may be
lowered. Accordingly, it is preferable that the level difference be within a range of
1.5 to 8.0 mn.
25 [0056]
A fourth surface 18-4 and a fifth surface 18-5 of the wedge-shaped bead 18
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Our Ref.: NNSC14045-IN
2 1
provided on the blatlk holder 12 are arranged at positions respectively corresponding
to the fourth surface 17-4 and the fifth surface 17-5 of the wedge-shaped bead 17
provided on the die 11. Accordingly, in a state of clamping the bla~lk 14 by the die
11 and the blank holder 12, the fourth surface 18-4 and the fifth surface 18-5 of the
5 wedge-shaped bead 18 respectively face the fourth surface 17-4 and the fifth surface
17-5 of the wedge-shaped bead 17 via the blank 14.
[0057]
Incidentally, although in the above description, a case where the wedgeshaped
bead 17, 18 has a stepped shape in which the first surface 17-1, 18-1 is
10 located lower than the third surface 17-3, 18-3 has been taken by way of example,
the stepped shape may be reversed. That is, the wedge-shaped bead 17, 18 may
have a stepped shape in which the first surface 17-1, 18-1 is located higher than the
third surface 17-3, 18-3.
[0058]
15 e. Manufacturing Method for Stretch-Formed Product>
Next, a manufacturing method for a stretch-formed product using the
manufactmitig apparatus for a stretch-fornled product according to the present
embodiment will be described together with an action of the lock bead. I11 the
following example, description will be made with reference to FIG. 1 to FIG. 4 as
20 appropriate by taking a case where the die 11 and the blank holder 12 are
respectively provided with the wedge-shaped beads 15 and 16 shown it1 FIG. 2 to
FIG. 4 by way of example. Also a case where the die 11 and the blank holder 12
are respectively provided with the wedge-shaped beads 17 and 18 showw~n in FIGS to
FIG.7 is understood sin~ilarly.
25 [0059]
In the manufacturing method for a stretch-formed product according to the
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Our Ref.: NNSC14045-IN
22
present enlbodirnent, a knoww~n process of the stretcll fornling can be adopted as the
entire process of the stretch fornling. Briefly describing, first, the blank 14 is
aligned and placed on the blank holder 12. Then, the margin of tile blank 14 is
clatnped by the clalnping surfaces lla and 12a of the die 11 and the blank holder 12
5 on which the wedge-shaped beads 15 and 16 are provided by relatively nloving the
die 11 toward the blank holder 12.
[0060]
The forming region 14b located at the center of the blank 14 is relatively
pressed toward the die 11 by relatively moving the punch 13 toward the die 11 in this
10 state. At this time, the clamp target part 14a of the blank 14 is clanlped by the
wedge-shaped beads 15 and 16 provided on the clamping surfaces I la and 12a such
that the blank 14 does not flow from the outer edge part of the blank 14 toward the
forming region 14b. Thereby, the stretch-formed product with no flowing of the
blank 14 into the forming region 14b is fo~med.
15 [0061]
At this time, w11en clamping the blank 14, for example, a load which is
about 200 t as a whole becomes necessary in some cases. Accordingl~: a clamping
function by the wedge-shaped beads 15 and 16 becomes important in order to
prevent flowing of the blank 14 into the forming region 14b even wvhile clamping the
20 blank 14 by applying a large load.
[0062]
In the present embodiment, as shown in FIG. 2 to FIG. 4, the wedge-shaped
bead 15, 16 has a stepped shape formed by the first surface 15-1, 16-1, the second
surface 15-2, 16-2 and the third surface 15-3, 16-3 fiom the outer edge toward the
25 center of each of the die 11 and the blank holder 12. The second surface 15-2, 16-2
intersects with the first surface 15-1, 16-1. The third surface 15-3, 16-3 intersects
PCT/JP2014/082GG4
Our Ref.: NNSC14045-IN
with the second surface 15-2, 16-2.
[0063]
The first surface 15-1, 16-1 has the fourth surface 15-4, 16-4 and sixth
surface 15-6, 16-6 facing each other it1 the extending direction of the wedge-shaped
5 bead 15, 16. Further, the first surface 15-1, 16-1 has the fifth surface 15-5, 16-5
which is arranged between tlie fourth surface 15-4, 16-4 and the sixth surface 15-6,
16-6 and intersects with tlie foorth surface 15-4, 16-4 and the sixth surface 15-6, 16-6.
[0064]
By configuring the wedge-shaped beads 15 and 16 in this way, the clamp
10 target part 14a of the blank 14 which is clamped by the wedge-shaped beads 15 and
16 becomes non-linear in section in a direction orthogonal to a direction going from
the outer edge part toward tlie forming region 14b of the blank 14. Thereby, the
bending rigidity of the blank 14 clamped by the wedge-shaped beads 15 and 16 is
improved atid the unbending resistance when the blank 14 is about to flow toward
15 the forming region 14b becomes large.
[0065]
In addition, on the clamp target part 14a of the blank 14, in a corner part
corresponding to the bounda~yp o~tiotb~e tween the first surface 15-1, 16-1 and the
second surface 15-2, 16-2 of the wedge-shaped bead 15, 16, the length of a part
20 which becomes non-parallel to a corner part correspo~~dintgo tlie boutidary poition
between the seco~ld surface 15-2, 16-2 and the third surface 15-3, 16-3 of the wedgeshaped
bead 15, 16 becomes long. Thereby, the unbending resistance when the
blank 14 is about to flow toward the forrnirig region 14b becollies large similarly.
[0066]
25 Accordingl]: in cooperation with the deformatior~re sistances ofb ending and
unbending deforr~~atioant the corner part of the step \vhich is formed by the first
PCT/JP2014/082FG4
Onr Ref.: NNSC14045-IN
24
surface 15-1, 16-1, the secoud surface 15-2, 16-2 and the third surface 15-3, 16-3 of
the wedge-shaped bead 15, 16 and the frictional resistances of the wedge-shaped
bead 15, 16 with the blank 14, flowing of the blank 14 from the outer peripheral part
14c into the fornling region 14b of the blank 14 can be effectively prevented.
5 [0067]
Accordingly, even in a case where the pressing length L1 by the wedgeshaped
beads 15 and 16 along the direction going from the outer peripheral part 14c
toward the forming region 14b of the blank 14 is made short, the blank clatnping
force required for the stretch forming is ensured. In the present embodiment, the
10 material yield of the blank 14 can be inlproved by the amount that the pressing length
L1 by the wedge-shaped beads 15 and 16 in the blank 14 can be shortened in this
way.
Examples
15 [0068]
In the following, Examples of the present invention will be described.
[0069]
(Evaluation 1)
In the Evaluation 1, a blank clamping perfornlance (a blank locking force)
20 of each bead was evaluated in accordance with a later described test procedure by
using a material sliding test device which is equipped with a blank clamping part
having the beads of each for111 formed on the die and the blank holder. ' The blank (a
test material) used is an alloyed hot dip galvanized steel sheet which is 0.7 Inln in
sheet thickness and is at the 340 MPa level in tensile strength measured by a tensile
25 test based OII JIS Z 2241.
[0070]
PCT/JP2014/082GG4
Our Ref.: NNSC14045-IN
25
In an Example 1 , tlie blank clatnping performance (the blank locking
perfor~nance) of the wedge-shaped beads 15 and 16 was evaluated by using the
material sliding test device which is equipped with the blank clamping part in which
the wedge-shaped beads 15 and 16 shown in FIG. 2 to FIG. 4 had been fornled. In
5 an Exaniple 2, the blank clanlping performance of the wedge-shaped beads 17 and 18
was evaluated similarly to the Exan~ple 1 except that a material sliding test device
\vl~ich is equipped with a blank clanlping part in which the wedge-shaped beads 17
and 18 shown in FIG. 5 to FIG. 7 had been formed is used.
1007 1 ]
10 In a Cotnparative example 1, the blank clamping performance of the
trapezoidal beads 2a and 3a was evaluated similarly to the Example 1 except that a
material sliding test device which is equipped with a blank clamping part in which
the conventional trapezoidal beads 2a and 3a shown in FIG. 15 to FIG. 17 had been
formed is used. In addition, in a Comparative example 2, the blank clamping
15 performance of stepped beads was evaluated sinlilarly to the Example 1 except that a
material sliding test device which is equipped with a blank clamping part in which
tlie stepped beads constituted by only stepped shapes that the first surfaces 15-1, 16-1,
17-1, and 18-1 in FIG. 2 and FIG. 5 are flattened had been fornled is used.
[0072]
20 [Test Procedure]
As shown in FIG. 8, a blank 54 of 60 mnl in sheet \vidtli is clamped by a die
61 and a blank holder 62 of each tilanufacturi~lga pparatus \vit11 pressing force per
unit length along the extending direction of the bead being set to 30 kgf/~nm. The
pressing length Ll of the blank 54 \vhich is clamped by clamping surfaces of the die
25 61 and the blank holder 62 was set as follows.
Example 1 (the wedge-shaped beads): L1 = 9.5 tnm
PC'I'/JP2014/082GG4
Our Ref.: NNSC14045-IN
26
Example 2 (the wedge-shaped beads): 1,l = 9.0 111111
Conlparative example 1 (the trapezoidal beads): L1 = 19.0 mm
Conlparative example 2 (the stepped beads): L1 = 9.0 tnm
[0073]
5 The blank 54 is nipped and held by a chuck 58 at a position where the
length LIP to an end of a clamp target part 55 to be clamped by the clamping surfaces
of the die 61 and the blank holder 62 having the respective beads reaches 135 mm.
The chuck 58 is moved from this state and the blank 54 is drawn out of the die 61
and the blank holder 62. In that occasion, the test was performed a plurality of
10 times by changing a drawing-out length in a variety of ways and a flowing-in length
was evaluated from a sliding mark generated on the blank 54 after each test.
[0074]
Here, time when the flowing-in length reaches about 1 mnl was defined as a
lock limit, that is, as a malfunction as the lock bead. Then, drawing-out force at the
15 lock limit (the flowing-in length = 1 mm), that is, the locking force was calculated
and evaluated by interpolating "data on drawing-out force - flowing-in length"
obtained in the above-mentioned tests. FIG. 9 is a gsaph showing a result of the
evaluations. In FIG. 9, the locking force is indicated by a relative value with the
locking force of the conventional trapezoidal beads 2a and 3a being set as 100%.
20 [0075]
As shown in FIG. 9, although the trapezoidal beads 2a and 3a in the
Conlparative exan~ple 1 exhibit a high locking force, the pressing length L1 by the
die and the blank holder is 19.0 mm and it is difficult to miniaturize the blank 54 by
shortening the pressing length L1. Accordingly, the Comparative exatilple 1 is low
25 in material yield of the blank 54. In addition, although the stepped bead in the
Comparative example 2 is 9.0 mtn in pressing length L1 and it is possible to shorten
PC'I'/JP2014/082G64
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27
the pressing length Ll, the locking force is about 70%. Accordingl~~t,h e
Conlparative example 2 cannot ensure the locking force required for the stretch
forming.
[0076]
5 In contrast thereto, the wedge-shaped beads 15, 16, 17, and 18 in the
Examples 1 and 2 are individually 9.5 mm and 9.0 mm in pressing length L1, it is
possible to shorten the pressing lengths L1 thereof equally to the Comparative
example 2 and the locking forces thereof reach 89% and 85% individually. In
particular, since the wedge-shaped bead in the Example 1 has the sixth surface
10 together with the fourth surface and the fifth surface, the locking force \vhich is
higher than that of the wedge-shaped bead in the Example 2 was ensured. The
wedge-shaped beads 15, 16, 17, and 18 in the Exat~lples 1 and 2 exhibit high locking
performances required for the stretch forming in this way. In addition, since the
wedge-shaped beads 15, 16, 17, and 18 in the Examples 1 and 2 can reduce the
15 pressing lengths L1 much more than the conventional trapezoidal beads, the yield of
material of the blank 54 can be improved much bette~
[0077]
(Evaluation 2)
In the Evaluation 2, the blank clamping performance (the blank locking
20 force), the material yield, the appearance of the clamp target part and the influence
on a product surface were each evaluated by drawing out the blank by using the
chuck si~nilarlyto the Evaluation 1, wvhile changing the shapes of the wedge-shaped
beads 15 and 16 sho\vn in FIG. 2 to FIG. 4 and the wedge-shaped beads 17 and 18
shown in FIG. 5 to FIG. 7. The blank (the test material) used is the alloyed hot dip
25 galvauized steel sheet wvhich is 0.7 mn in sheet thickness and is the 340 MPa level in
tensile strength measured in the tensile test based on JIS Z 2241 sinlilarly to the
PCT/JP2014/082664
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28
Evaluation 1. Table 1 indicates the shapes of the wedge-shaped beads and
evaluation results. Examples 3 to 9 and Colnparative exalnples 3 to 7 pertain to the
wedge-shaped beads 15 and 16 wvliich have a trapezoidal wedge shape (a square is
included) and Examples 10 to 14 and Comparative examples 8 to 12 pertain to the
5 wedge-shaped beads 17 and 18 which have a triangular wedge shape.
[0078]
[Table 11
[0079]
10 In the Comparative examples 7 and 12, "Absence of Step" indicates a form
in \vI~ich the second surfaces 15-2, 16-2, 17-2 and 18-2 and the third surfaces 15-3,
16-3, 17-3 and 18-3 in FIG. 2 and FIG. 5 are not provided and the wedge-shaped
PCT/JP2014/082GG4
Our Ref.: NNSC14045-IN
29
beads are forn~ed on flat surfaces. The wedge pitch in a case of the trapezoidal
wedge shape corresponds to the pitch interval when the set of the protruded shape
and the depressed shape of the trapezoid is defined as one pitch with the position
where the wedge height is 112 being set as the reference. In addition, the wedge
5 pitch in a case of the triangular wedge shape corresponds to the length of the base of
the triangle. The wedge wall angle means the rising angles of the fourth surfaces
15-4 and 16-4 and the sixth surfaces 15-6 and 16-6 in the case of the trapezoidal
wvedge shape, and means the rising angles of the fourth surfaces 17-4 and 18-4 and
the fifth surfaces 17-5 and 18-5 in the case of the triangular wedge shape.
10 [0080]
FIG. 10 shows the sliding marks on the blank individually in a case where
decision on the locking performance is good and in a case where it is bad. A
photograph showtl at the top of FIG. 10 is a photograph obtained by photographing
the blank in the case where decision on the locking performance is bad fiom the
15 blank holder side, and a photograph shown at the bottom of FIG. 10 is a photograph
obtained by photographing the blank in the case where decision on the locking
perfor~nance is good from the blank holder side. 111 the case where decision on
locking is bad, the sliding mark on the blank is observed from a corner of the
boundary between the second surface and the third surface to the third surface side.
20 In contrast thereto, in the case where decision on locking is good, few sliding marks
are observed on the blank.
[008l]
As indicated on the Table 1, in case of the wedge-shaped bead having a
trapezoidal wedge shape, the Comparative example 3 it1 which the pitch interval is
25 80 I~III, the Comparative exan~ple 4 in which the wedge height is 0.5 mm, the
Comparative example 5 in which the wedge \vall angle is 15 degrees and the
PCl'/JP2014/082664
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30
Coniparative exalilple 7 in whicli there is no step have lowered locking perfor~uance
and it was tlot possible to ensure the locking force required for the stretch for~uing.
Among them, in regard to the Colnparative example 7, the influence on the product
surface was also observed. In regard to tlie Comparative example 5, it is
5 co~lceivable that it is affected by increase in the wedge pitch in combination with a
small wedge wall angle. In addition, in the Comparative example 6 in wvl~ich the
wedge height is 20.0 mm, the blank of tlie clanlp target part was destroyed, the
locking force could not be evaluated and also the material yield was lowered.
[0082]
10 On the other hand, it was found that in the case of the wedge-shaped bead
having the trapezoidal wedge shape, if the pitch intend is witliin a range of 5 to 50
tntn and tlie wedge height is within a range of 1.0 to 10.0 rnm, the lockilig force
required for the stretch forming can be ensured and also the material yield of the
blatlk can be improved.
15 [0083]
Meanwhile, in the case of tlie wedge-shaped bead having the triangular
wedge shape, the Colnparative examples 8, 9, 11, and 12 in which the wedge \ d l
angle is 4 degrees or 6 degrees have lowered lockilig performance and it was not
possible to ensure the lockillg force required for the stretch forming. In addition, in
20 the Comparative exanlple 10 it1 which tlie wedge height is 10.0 mm, the wedge wall
angle reached 45 degrees, the blank of the clamp target part was destroyed, the
wrinkles were generated on the blank, the lockillg force could not be evahmted and
also tlie material yield was lowered.
[0084]
25 On the other hand, in the case of the wedge-shaped bead having the
triangular wedge shape, it was found that, if the pitch interval is within a range of 5
PC'l1/JP2014/082664
Our Ref.: NNSC14046-IN
3 1
to 50 111111 and the wedge wall angle is within a range of 10 to 40 degrees, the locking
force required for the stretch fornling can be ensured and also the material yield of
the blank call be improved.
[OOSS]
5 (Evaluation 3)
In the Evaluation 3, in regard to the case where the wedge-shaped bead was
used and the case where the cor~ventional trapezoidal bead was used, the material
yield of the blank was individually evaluated. FIG. 11 atid FIG. 12 are diagrams
showi~tgth e blank and an outline shape of the stretcli-fortned product manufactured
10 it1 the Example and the Comparative exanlple. FIG. 11 is a front view of the blank
of the stretch-formed product and FIG. 12 is a perspective view showi~ig the
dimension of each part of the stretch-formed product. The stretch-formed product
is a formed product which has been formed modeling after the door outer panel.
[0086]
15 In the Example, the stretch forming was perfonned by using the die and the
blallk holder having the wedge-shaped beads 15 and 16 shown in FIG. 2 to FIG. 4
and the stretch-formed product shown in FIG. 11 and FIG. 12 was manufactured.
In addition, as the Comparative example, the stretch forming was perfornled by using
the die and the blank holder having the conventional trapezoidal beads show11 in FIG.
20 15 to FIG. 17 and the stretch-formed product shown in FIG. 11 and FIG. 12 was
manufactured. In the both, the blank used was the alloyed hot dip galvanized steel
sheet wlich is 0.7 mm in sheet thickness atid is at the 340 MPa level in tensile
stre~~gmthe asured in the telisile test based on JIS Z 2241. In both cases, the blank
of a minimum area which would not hinder the stretch fornling was used.
25 [0087]
The pressing length L1 of the clamp target part of the blank to be cla~llped
PCl'/JP2014/082GG4
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32
by each lock bead was 9.5 111111 in the Exanlple and 19.0 111111 in the Comparative
example. Consequently, while the area of the blank in the Exa~ilple was about
1.372 n12, the area of the blank in the Con~parative example was 1.425 n12.
Accordingly, in the case where the wedge-shaped beads of the Example were used,
5 the yield of material in the stretch forming was improved by about 4% in comparison
with the case where the trapezoidal beads of the Comparative exanlple were used.
At present, inlprovement of the yield of material in the stretch fonning is in a
situation that it almost reaches its limit and it is an extremely noticeable effect that
the yield of the material can be improved by about 4%.
10
Reference Signs List
10 manufacturing apparatus
1 die
1 la clamping surface
12 blank holder
12a claniping surface
13 punch
14 blank
14a clamp target part
14b forming region
14c outer peripheral part
14d trim line
15, 16, 17,18 wedge-shaped bead (lock bead)
15-1, 16-1, 17-1, 18-1 first surface
15-2, 16-2, 17-2, 18-2 second surface
PCT/JP2014/082GG4
Our Ref.: NNSC14045-IN
15-3, 16-3, 17-3, 18-3 third surface
15-4, 16-4, 17-4, 18-4 fourth surface
15-5, 16-5, 17-5, 18-5 finh surface
15-6, 16-6 sixth surface
54 blank
55 clamp target part
58 chuck
61 die
62 blank holder
PCT/JP2014/082GG4
Our Ref.: NNSC1.1045-IN
34

CLAIMS
Claim 1
A manufacturing apparatus for a stretch-formed product, the ~nanufacturing
5 apparatus comnprising:
a die and a blank holder which have clamping surfaces facing each other;
a punch that, in a state where a margin of a blank of a sheet material is
clamped by the clamping surfaces of the die and the blank holdel; relatively presses a
forming region of the blank into the die and thereby performs stretch forming on the
10 forming region of the blank, and
lock beads that are provided on the clamping surfaces of the die and the
blank holder in mutually similar shapes and have first surfaces, second surfaces that
intersect with the first surfaces, and third surfaces that intersect with the second
surfaces from outer edges toward the centers of the die and the blank holder, the first
15 surfaces each having a plurality of depression-prot~usionp atts.
Claim 2
The manufacturing apparatus for a stretch-fornled product accordir~g to
claim 1, wherein
20 when the plurality of depression-protrusion parts are viewed from the outer
edge toward the center of the blank holder, the plurality of depression-protrusion
parts have any shape of a trapezoidal shape, a rectangular shape and a triangular
shape or a combined shape thereof.
25 Claim 3
The tnanufacturing apparatus for a stretch-fonned product accordi~lg to
PCT/JP2014/0826G~l
Our Ref.: NNSC14045-IN
35
claim 1 or 2, \vherein .
the plurality of depression-protrusion parts each have a fourth surface and a
fifth surface intersecting with each other, the fourth surface atid the fifth surface
intersect with the second surface, and at least one of the fourth surface and the fifth
5 surface itltersects with the first surface.
Claim 4
The manufacturing apparatus for a stretch-formed product according to
claim 3, wherein
10 the plurality of depression-protrusion parts each have the fourth surface and
a sixth surface facing eacli other and the fifth surface that intersects \vitli the fourth
surface and the sixth surface, the fourth surface, the fifth surface and the sixth
surface intersect with the second surface, and at least one of the fourth surface, the
fifth surface and the sixth surface intersects with the first surface.
Claim 5
The ma~iufacturing apparatus for a stretch-formed product according to
claim 2 or 3, wherein
in a case where the plurality of depression-protrusion parts each have the
20 tria~lgulars hape, a pitch interval of the plurality of depression-protrusion parts \vl~en
the triangular shape is defined as one pitch is withiti a range of 5 to 50 mtn, and a
rising angle of a surface of the depressioti-protrusion part is within a range of 10 to
40 degrees.
25 Claim 6
The ~nanufacturitiga pparatus for a stretch-forliied product according to ally
~CTIJP2014i082~~4
Our Ref.: NNSC14045-IN
36
one of claims 2 to 4, wherein
'in a case where the plurality of depression-protrusion parts each have the
trapezoidal shape or the rectangular shape, a pitch interval of the plurality of
depression-protrusion parts when a set of a protruded shape and a depressed shape is
5 defined as one pitch is within a range of 5 to 50 lnrn and a Ileight of the depressionprotrusioil
part is within a range of 1.0 to 10.0 mm.
Claiin 7
' A nianufacturing method for a stretch-formed product,. the manufacturing
10 method comprising the steps o t
placing a blank of a sheet material between a die and a blank holder which
include, on clampi~igs urfaces facing each other, lock beads that have first surfaces,.
. U ~
second surfaces that intersect with the first surfaces and third surfaces that intersect
with the second surfaces fiom outer edges toward the centers, the first surfaces each
15 having a plurality of depression-protrusion palls, and the lock heads being provided
in n~utuallys imilar shapes;
clamping a margin of the blank by the die and the blank holder; and
stretch-forming the blank by relatively pressing a forming region of the
blank into the die by a punch in a state of clamping the margin of tlie blank.