DESCRIPTION
Title of Invention: Method of Producing Shaped Steel
Changing in Cross-Sectional Shape in Longitudinal
5 Direction and Roll Forming Apparatus for Same
Technical Field
[OOOl] The present invention relates to a method and
apparatus for roll forming for producing a shaped steel
10 which varies in cross-sectional shape in the longitudinal
direction.
Background Art
[0002] As a method of producing a hat-shaped steel,
which is one type of shaped steel, press forming using a
15 punch and die is widely known. In bending into a hdL
shape by press forming, the problem of springback, that
is, the sheet material trying to return to its original
state due to the reaction force when the press pressure
is removed, easily arises, and therefore in the past,
2 0 countermeasures for suppressing springback have been
studied.
[0003] In this regard, in recent years, use of high
tensile steel has been expanding. As one example, in the
automobile industry, it is believed that reduction of the
2 5 weight of the vehicle body will lead to reduction of the
amount of emission of C02 and therefore high tensile steel
is being proactively used for the vehicle body material.
For this reason, on the production floor of shaped
steels, the problem of the springback due to the high
3 0 strength characteristics of steel materials has been
surfacing. Furthermore, in recent years, high tensile
steel which has an over 980 MPa tensile strength has also
been being produced. With general press forming, it is
difficult to produce a hat-shaped steel as designed from
35 such high tensile steel.
[0004] As another method of producing a shaped steel,
the roll forming method is known. Roll forming is, for
example, a continuous bending process which runs a strip,
which is taken out from a coil, through roll units
provided at a plurality of successively arranged
stations. Roll forming is, in particular, suitable for
5 forming H-beams, L-beams, and other steel products and
pipes and other long products with constant crosssectional
shapes in the longitudinal direction. On the
other hand, roll forming, unlike press forming (drawing),
is not suited for forming a shaped steel which varies in
10 cross-sectional shape in the longitudinal direction.
[0005] PLTs 1 to 3 disclose the art of roll forming to
produce a shaped steel which varies in cross-sectional
shape in the longitudinal direction by variable control
of the roll widths of split rolls. However, the roll
15 forming process and apparatus disclosed in PLTs 1 to 3
have the problem of a complicated structure and method of
control of the apparatus. For this reason, it is
difficult to convert existing facilities for use for
working the inventions of PLTs 1 to 3. Introduction of
2 0 new facilities is necessary, and therefore the cost
becomes high.
[0006] Further, if, as in the inventions of PLTs 1 and
3, broadening the roll widths of the split rolls during
roll forming, there are the problems that only the corner
2 5 parts at the front sides of the rolls will linearly
contact the steel sheet material and, in high tensile
steel or other materials, stiffness of a mill is
insufficient, and therefore it is not appropriate for
mass production.
30
Citations List
Patent Literature
[00071 PLT 1: Japanese Patent Publication No. H10-
314848 A
3 5 PLT 2: Japanese Patent Publication No. H7-88560 A
PLT 3: Japanese Patent Publication No. 2009-500180A
Summary of Invention
Technical Problem
[OOOS] The present invention was made to solve the
above problem and has as its object to provide art which
5 enables production of a shaped steel which varies in
cross-sectional shape in the longitudinal direction by
simple roll forming without the need for complicated
control and apparatuses such as in the prior art.
[0009] Further, another object of the present
10 invention is to provide art which enables suppression of
insufficiency in stiffness of a mill when using, for
example, high tensile steel, in the case of producing a
shaped steel, which varies in cross-sectional shape in
the longitudinal direction, by roll forming.
15
Solution to Problem
[OOlO] To solve the above-mentioned problem, according
to the present invention, there is provided a method of
producing a shaped steel which varies in cross-sectional
2 0 shape in the longitudinal direction from a sheet by roll
forming, comprising: a step of preparing a first rolling
die which has a rotation shaft and an annular ridge part
which varies in cross-sectional shape in a
circumferential direction which is centered about the
2 5 rotation shaft; a step of arranging the first rolling die
so that the rotation shaft of the first rolling die
becomes perpendicular to a sheet feed direction; a step
of preparing a second rolling die which has a rotation
shaft and an annular groove part which varies in cross-
30 sectional shape in a circumferential direction which is
centered about the rotation shaft; a step of arranging
the second rolling die so that a gap which is equal to a
thickness of the sheet is formed between the first
rolling die and second rolling die and the annular ridge
35 part of the first rolling die and the annular groove part
of the second rolling die engage; a step of making the
first rolling die and the second rolling die rotate
synchronized; and a step of feeding a sheet between the
first rolling die and second rolling die, wherein the
side surfaces of the annular ridge part of the first
rolling die are provided with relief so that the gap with
5 respect to side surfaces of the annular groove part of
the second rolling die broadens inward in the radial
direction over an entire of the circumference.
[ 00111 Furthermore, the present invention has as its
gist a roll forming apparatus for roll forming use for
10 producing a shaped steel which varies in cross-sectional
shape in the longitudinal direction from a sheet,
comprising: a first rolling die which has a rotation
shaft and an annular ridge part which varies in crosssectional
shape in a circumferential direction which is
15 centered about the rotation shaft, the first rolling die
arranged so that the shaft of the first rolling die
becomes perpendicular to a sheet feed direction; a second
rolling die which has a rotation shaft and an annular
groove part which varies in cross-sectional shape in a
2 0 circumferential direction which is centered about the
rotation shaft, the second rolling die arranged so that
the rotation shaft of the second rolling die becomes
parallel to the rotation shaft of the first rolling die;
and a drive device which synchronizes and rotationally
2 5 drives the first rolling die and the second ro&ling die,
the first rolling die and second rolling die being
arranged relatively so that a gap which is equal to a
thickness of the sheet is formed between the two and the
annular ridge part of the first rolling die and the
30 annular groove part of the second rolling die engage,
wherein the side surfaces of the annular ridge part of
the first rolling die are provided with relief so that
the gap with respect to side surfaces of the annular
groove part of the second rolling die broadens inward in
35 the radial direction over an entire of the circumference.
Advantageous Effects of Invention
[0012] According to the present invention, by using a
first rolling die having an annular ridge part which
varies in cross-sectional shape in the circumferential
direction and a second rolling die having an annular
5 groove part which receives the annular ridge part of the
first rolling die while maintaining a gap with the
annular ridge part of the amount of thickness of the
shaped steel, by simple control for making at least the
first and second rolling dies rotate synchronized, a
10 shaped steel with a cross-sectional shape which varies in
the longitudinal direction can be produced. Accordingly,
complicated control such as variable control of the roll
widths of split rolls for broadening the width of the
cross-section becomes unnecessary. Further, it is
15 possible to realize the rolling forming apparatus of the
present invention by changing the rolls of existing roll
forming apparatuses to the first and second rolling dies.
[0013] In addition, according to the present
invention, by using the first and second rolling dies
20 which have the above-mentioned roll barrel parts, even if
the cross-sectional shape varies in the longitudinal
direction, shaping is possible in the state where the
roll barrel parts and material contact sufficiently on
surface to each other, and therefore it is possible to
2 5 suppress insufficiency in stiffness of a mill when using,
for example, high tensile steel.
Brief Description of Drawings
[0014] [FIG. lA] FIG. 1A is a perspective view of a
30 hat-shaped steel which varies in cross-sectional shape in
the longitudinal direction, as seen from above.
[FIG. lB] FIG. 1B is a perspective view of a hat-shaped
steel which varies in cross-sectional shape in the
longitudinal direction, as seen from below.
35 [FIG. 21 FIG. 2 is a schematic perspective view of a
multistage roll forming apparatus according to a first
embodiment of the present invention.
[ F I G . 31 F I G . 3 is a vertical view of a roll unit of the
multistage roll forming apparatus of F I G . 2.
[ F I G . 41 F I G . 4 is a disassembled perspective view of a
pair of top and bottom rolling dies of the roll unit of
5 F I G . 3.
[ F I G . 5A] F I G . 5.4 is a view showing a bending process at
different stages of the multistage roll forming apparatus
of F I G . 2 and a view showing a step of forming flanges of
a hat-shaped steel.
10 [ F I G . 5 B ] F I G . 5 B is a view showing a bending process at
different stages of the multistage roll forming apparatus
of F I G . 2 and a view showing a step of forming a top wall
of a hat-shaped steel.
[ F I G . 61 F I G . 6 is a schematic perspective view for
15 explaining the action in one roll unit.
[ F I G . 7 A ] F I G . 7A is a perspective view of a hat-shaped
steel which has a bead.
[ F I G . 7 B ] F I G . 7B is a perspective view of rolling dies
which form the hat-shaped steel of F I G . 7A.
2 0 [ F I G . 81 F I G . 8 shows rolling dies according to a second
embodiment.
[ F I G . 91 F I G . 9 is a partial cross-sectional view of the
rolling dies of F I G . 8.
[ F I G . 101 F I G . 10 is a chart which shows a minimum gap
2 5 when providing relief at the rolling dies.
[ F I G . 111 F I G . 11 is a chart explaining a relationship
between a relief amount x and a side wall angle 8 of a
shaped steel and a height H of an annular ridge part of a
bottom roll.
30 [ F I G . 12Al F I G . 1 2 A is a perspective view which shows
interference between a top roll and a bottom roll when
not providing relief and shows together a hat-shaped
steel.
[ F I G . 1 2 B ] F I G . 1 2 B is a perspective view which shows
35 interference between a top roll and a bottom roll when
not providing relief and shows together a hat-shaped
steel.
[ F I G . 1 3 A l F I G . 1 3 A is a chart explaining a relationship
between a relief amount x, and a side wall angle 8 of a
shaped steel and a height H of an annular ridge part of a
bottom roll.
5 [ F I G . 1 3 B l F I G . 1 3 B is a partially enlarged view of a
bottom roll which shows a relief amount x, a side wall
angle 0 of a shaped steel, and a height H of an annular
ridge part.
[ F I G . 1 3 C l F I G . 1 3 C is a table which shows minimum gaps
1 0 between the top and bottom rolls.
[ F I G . 1 4 1 F I G . 1 4 is a perspective view which shows
another example of a multistage roll forming apparatus.
[ F I G . 151 F I G . 15 is a view which shows a bendirig process
at different stages of the multistage roll forming
15 apparatus of F I G . 1 8 .
[ F I G . 1 6 A l F I G . 1 6 A is a chart explaining a relationship
between a relief amount x, and a side wall angle 8 of a
shaped steel and a height H of an annular ridge part of a
bottom roll.
2 0 [ F I G . 1 6 B ] F I G . 1 6 B is a partially enlarged view of a
bottom roll which shows a relief amount x, a side wall
angle 8 of a shaped steel, and a height H of an annular
ridge part.
[ F I G . 1 6 C ] F I G . 1 6 C is a table which shows minimum gaps
2 5 between the top and bottom rolls.
[ F I G . 1 7 1 F I G . 1 7 is a view which shows a start point of
relief provided at an annular ridge part of a bottom
roll.
[ F I G . 1 8 A l F I G . 1 8 A is a perspective view of a shaped
3 0 steel according to a third embodiment.
[ F I G . 1 8 B l F I G . 1 8 B is a perspective view of rolling dies
according to a third embodiment which is shown together
with the shaped steel of F I G . 1 8 A .
[ F I G . 19AI F I G . 1 9 A is a perspective view of a shaped
35 steel according to a fourth embodiment.
[ F I G . 1 9 B I F I G . 1 9 B is a perspective view of rolling dies
according to a fourth embodiment which is shown together
with the shaped steel of F I G . 19A.
[ F I G . 20Al F I G . 20A is a perspective view of a shaped
steel according to a fifth embodiment.
5 [ F I G . 20B] F I G . 20B is a perspective view of rolling dies
according to a fifth embodiment which is shown together
with the shaped steel of F I G . 20A.
[ F I G . 21AI F I G . 21A is a perspective view of a shaped
steel according to a sixth embodiment.
10 [ F I G . 21Bl F I G . 21B is a perspective view of rolling dies
according to a sixth embodiment which is shown together
with the shaped steel of F I G . 21A.
[ F I G . 22Al F I G . 22A is a perspective view of a shaped
steel according to a seventh embodiment.
15 [ F I G . 22Bl F I G . 22B is a perspective view of rolling dies
according to a seventh embodiment which is shown together
with the shaped steel of F I G . 22A.
[ F I G . 23Al F I G . 23A is a perspective view of a shaped
steel according to an eighth embodiment.
20 [ F I G . 23B] F I G . 23B is a perspective view of rolling dies
according to an eighth embodiment which is shown together
with the shaped steel of F I G . 23A.
[ F I G . 24Al F I G . 24A is a perspective view of a shaped
steel according to a ninth embodiment.
2 5 [ F I G . 24B] F I G . 24B is a perspective view of rolling dies
according to a ninth embodiment r.rhich is Sh0trn together
with the shaped steel of F I G . 24A.
[ F I G . 25Al F I G . 25A is a perspective view of a shaped
steel according to a 10th embodiment.
30 [ F I G . 25B] F I G . 25B is a perspective view of of rolling
dies according to a 10th embodiment which is shown
together with the shaped steel of F I G . 25A.
[ F I G . 26A] F I G . 26A is a perspective view of a shaped
steel according to an llth embodiment.
3 5 [ F I G . 26B] F I G . 26B is a perspective view of rolling dies
according to an llth embodiment which is shown together
with the shaped steel of F I G . 26A.
Description of Embodiments
[0015] Below, a method of production of a shaped steel
which varies in cross-sectional shape in the longitudinal
5 direction and a roll forming apparatus for the same
according to preferable embodiments of the present
invention will be explained in detail, while referring to
the attached drawings. However, the embodiments explained
below shall not cause the present invention to be
10 interpreted limited in technical scope in any way.
[0016]
First, the shaped steel produced in the present
embodiment will be explained. The shaped steel which is
shown in FIGS. 1A and 1B is one example of a hat-shaped
15 steel of a saddle shape which varies in cross-sectional
shape in the longitudinal direction (for example, the
metal stock axis direction). FIG. 1A is a perspective
view of the hat-shaped steel seen from the upper side,
while FIG. 1B is a perspective view seen from the lower
2 0 side. The hat-shaped steel 1 comprises a top wall, side
walls which extend along the two side edge parts of the
top wall, and flanges which extend along the edge parts
at the opposite sides of the side walls, and has a crosssection
vertical to the longitudinal direction of the
2 5 hat-shaped steel 1 (lateral cross-section) which is
substantially hat shaped.
[00171 The hat-shaped steel 1 further has "portions
10a, lob having top wall width of L1, a portion 11 having
top wall width of L2 (>Ll), and tapered transition
30 portions 12a and 12b having expanding (or contracting)
top wall width of L1 to L2. The hat-shaped steel 1 has
hat-shape horizontal cross-sections with side walls which
flare outward at the portions 10a to 12b. The side walls
may have gradient angles which differ at the portions 10a
35 to lob or which are the same at the portions 10a to lob.
Further, the thickness of the steel shape can, for
example, be set to various thicknesses according to the
specifications, applications, etc. However, in the
present embodiment, the different portions 10a to 12b are
not individually shaped and joined by welding etc., but
are integrally shaped from a single sheet or strip by
5 roll forming. Therefore, the boundary lines between
portions of FIG. 1 are lines for convenience of
explanation and are not join lines or bend lines.
[0018] Furthermore, the flanges 13 formed at the
opening part of the bottom surface side along the
10 longitudinal direction are also obtained by bending the
sheet or strip by roll forming. Further, the corner parts
which formed by bending can, for example, have chamfered
shapes or rounded shapes such as shown in FIG. 1.
[0019] The type and strength of the material are not
15 particularly limited. All metal materials which can be
bent can be covered. As examples of the metal material,
there are carbon steel, alloy steel, nickel-chromium
steel, nickel-chromium-molybdenum steel, chromium steel,
chromium-molybdenum steel, manganese steel, and other
2 0 steel materials. If based on strength, steel with tensile
strengths of 340 MPa or less can be roughly classified as
general steel and steel with higher strengths can be
roughly classified as high tensile steel, but in the
present embodiment, either can be applied. Furthermore,
2 5 high tensile steel includes steel of for example the 590
MPa grade or 780 MPa grade. Currently, steel of the 980
MPa grade called "ultra high tensile steel" are being
produced. Regarding ultra high tensile steel, sometimes
bending into hat shapes becomes difficult with
30 conventional press forming (drawing), but with the roll
forming of the present-embodiment, 980 MPa or more ultra
high tensile steel can also be applied. Furthermore, as
examples of materials other than steel materials, there
are the poorly malleable materials including titanium,
35 aluminum, or magnesium or their alloys.
[00201 Next, the roll forming apparatus for producing
a steel shape which varies in cross-sectional shape in
the longitudinal direction will be explained. FIG. 2
shows a multistage roll forming apparatus 2 for producing
the above-mentioned hat-shaped steel as one embodiment of
a roll forming apparatus. The multistage roll forming
5 apparatus 2 comprises, for example, a plurality of roll
' units 20a to 20k which are successively arranged in the
sheet or strip feed direction. Due to this, a long sheet
or strip M is conveyed from the upstream side roll unit
20k to the downstream side roll unit 20a while bending it
10 in stages to obtain the final target product shape. The
finally shaped sheet or strip M is successively cut into
product units.
[0021] The rolling dies of the roll unit 20a of the
downstream-most station (final station) (below, sometimes
15 referred to as the "finishing rolls") are shaped
corresponding to the target product shape. The rolling
dies of the stations at the upstream side from the
finishing rolls are designed so that intermediates which
approach the final product shape in stages the further
20 toward the downstream side are formed at the different
stages. FIG. 2 shows one example of the rolling dies
which form a final product from a sheet or strip M in 10
stages. At each of the entry station to the fifth station
which perform the first half bending process, the roll
25 units 20j to 20f have the dies which have the projecting
shape roll barrel parts at the top side and the dies
which have the recessed shape roll barrel parts at the
bottom side.
[0022] On the other hand, at each of the fourth
3 0 station to the 10th station which perform the second half
bending process, the roll units 20e to 20a have the dies
which have the annular ridge parts at the bottom side and
the dies which have the annular groove parts at the top
side. Further, the entry station (roll unit 20k: 0th
35 station) to fifth station (roll unit 20f) are the first
half process for forming the flanges 13 (flange bending)
and the sixth station (roll unit 20e) to the final
station or the 10th station (roll unit 20a) are the
second half process for forming the top wall of the hatshaped
steel 1 (top wall bending).
[0023] The roll unit 20k of the entry station has
5 rolling dies having plain cylindrical shape arranged at
both the top and bottom. Further, the roll units 20j to
20f from the first station to the fifth station become
gradually smaller in diameters in the directions toward
the ends at both two end portions of the top rolls, while
10 the two end portions of the roll barrel parts of the
bottom rolls become gradually larger in diameter in the
directions toward the ends. Further, the gradient angles
of the two end portions of the dies become sharper in
order from the first station to the fifth station. At the
15 roll unit 20f of the fifth station, the two ends of the
sheet or strip M are bent about 90°, whereupon the flanges
13 are formed. The dies have, in the circumferentzial
direction, parts of narrow widths and wide widths and
parts of tapers of increasing/decreasing width, at the
2 0 centers of the roll barrel parts, so that flanges 13 of
the portions 10a to 12 of the shaped steel are formed.
[0024] On the other hand, the roll units 20e to 20a
from the sixth station to the final station have bottom
rolls with annular ridge parts in which the center of the
2 5 roll barrel parts are raised in projecting shapes and
have top rolls with annular groove parts in which the
center of the roll barrel parts are sunk in recessed
shapes. Further, more specifically, the annular ridge
parts of the bottom rolls and the annular groove parts of
30 the top rolls comprises narrow width parts, wide width
parts, and tapered parts with increasing width/decreasing
width, arranged in the circumferential direction, so that
the top walls of the portions 10a to 12 of the hat-shaped
steel 1 are formed.
35 [0025] The gradient angles of the side surfaces of the
annular ridge parts and annular groove parts of the rolls
become sharper in the order from the sixth station to the
final station. At the roll unit 20a of the final station,
the side walls of the sheet or strip M are bent about 90°
whereby the top wall of the hat is formed. However, the
configuration of the rolling dies which is shown in F I G .
5 2 is one example. The number of units arranged can be
suitably changed. Further, the rolling dies which are
arranged at the upstream side of the finishing rolls can
be further suitably changed in shapes.
[0026] Note that, in the present embodiment, the
10 cross-sectional shape is not just increased in width.
After the portion 11 where the width becomes maximum,
portions 12b and lob which are decreased in widths are
formed by the rolls, and therefore the intervals between
the roll units 20a to 20k are set to at least the lengths
15 of the products.
[0027] Next, the configuration of the roll units 20a
to 20k will be explained. F I G . 3 shows the overall
structure of the roll unit 20a in which the finishing
rolls are assembled. The roll unit 20a is provided with a
20 first rolling die which has a rotation shaft 31 which
extends in a sheet or strip feed direction, for example,
the horizontal direction (below, referred to as a "bottom
roll 3") and a second rolling die which has a rotation
shaft 41 which is parallel to the shaft 31 of the first
2 5 roll die 3 and faces the bottom roll 3 across a slight
gap (below, referred to as a "top roll 4").
[0028] The shafts 31 and 41 of the rolls 3 and 4 are,
for example, rotatably supported by ball bearings or
other bearing mechanisms 5 at stands or other support
30 members 51. The rolls 3 and 4 are supported to be able to
be raised and lowered and can be adjustable in distance
of separation of the rolls. Furthermore, it is also
possible to use a hydraulic pressure cylinder or other
pressing device to enable adjustment of the pressing
35 forces of the top and bottom rolls 4 and 3.
[0029] The top and bottom rolls 4 and 3 are driven to
rotate synchronized by a gear set 52. The gear set 52
comprises gears 52a and 52b which are coupled with the
shafts 31 and 41 respectively and are engaged with each
other. FIG. 3 shows, as one example of the gear set 52,
the top and bottom gears 52a and 52b which are formed by
5 spur gears. Further, at one end of the shaft 31 of the
bottom roll 3, for example, a drive motor or other drive
device 53 is connected. If this drive device 53 makes the
bottom roll 3 rotate, the top roll 4 is driven to rotate
through the gear set 52. At this time, for example, by
10 setting the top and bottom gear ratios the same, the top
and bottom rolls 4 and 3 rotate synchronously at the same
peripheral speeds. That is, the gear set 52 is also the
synchronized rotation mechanism of the top and bottom
rolls 4 and 3.
15 [0030] The gear set 52 only need make the top and
bottom rolls 4 and 3 rotate synchronously by the same
peripheral speed. The gears need not be spur gears such
as shown in FIG. 3 of course. Furthermore, it need not be
configured to drive the top roll 4 through the gear set
2 0 52. Individual drive mechanisms may also be connected to
the top and bottom rolls 4 and 3. It is also possible to
use an inverter controllable drive motor to adjust the
rotational speed.
[0031] The top and bottom rolls 4 and 3 which are
2 5 arranged at the final station are shaped corresponding to
the target product shape. Specifically, as shown in FIGS.
3 and 4, the bottom roll 3 has flank parts 32 which roll
the top surfaces of the flanges 13 and an annular ridge
part 33 which rises up at the center portion in the axial
3 0 direction of the flank parts 32 from the outer surface in
a projecting shape and rolls the inside part of the hat
shape. The cross-sectional shape of the annular ridge
part 33 exhibits a frustoconical shape which varies in
the circumferential direction corresponding to the hat
35 shape of the finished product.
[0032] That is, the annular ridge part 33 has a region
33a which is set in width of the outer circumferential
surface to the first roll width, a region 33b which is
set in width of the outer circumferential surface to the
second roll width, and tapered regions (in the following
explanation, sometimes called the "transition parts") 33c
5 and 33d which are arranged between the regions 33a and
33b and vary in widths of the outer circumferential
surfaces from the first roll width to the second roll
width. The left and right side surfaces of the annular
ridge part 33 form slanted surfaces which expand to the
10 outward sides the further toward the shaft 31 side.
Further, the width and height of the annular ridge part
33 and the gradient angle of the side surfaces are
dimensions which correspond to the width and height and
the gradient angle of the target hat shape. Furthermore,
15 the corner parts at the outsides of the annular ridge
part 33 and the corner parts at the insides of the flank
parts 43 are rounded or are chamfered. Note that, FIG. 4,
like FIG. 1, shows the borderlines of the regions 33a,
33b, 33c, and 33d for convenience of explanation.
2 0 [0033] The region 33b of the annular ridge part 33
forms the portion 11 of the width L2 of the hat-shaped
steel 1, while the regions 33c and 33d form the tapered
portions 12a and 12b of the hat-shaped steel 1.
Therefore, the arc length of the region 33b is set to the
25 length of the portion 11, while the arc lengths of the
regions 33c and 33d are set to lengths of the portions
12a and 12b. On the other hand, the region 33a of the
annular ridge part 33 forms both the portions 10a and lob
of the hat-shaped steel 1. Therefore, the arc length of
3 0 the region 33a is set to a length corresponding to the
sum of the lengths of the portions 10a and lob. In this
case, the intermediate point which equally divides the
region 33a becomes the start point of the roll. However,
when a continuous sheet or strip M for continuous forming
35 is used and the finally shaped product is successively
cut downstream of the apparatus, regions giving cutting
margins may also be added to the regions 33a. In this
case, a mark for indicating the cutting position (for
example, small hole, projection, etc.) may also be formed
at the surface of the sheet or strip M.
[0034] On the other hand, the top roll 4 is formed to
5 face the roll barrel part of the bottom roll 3 across a
gap of the amount of thickness of the hat-shaped steel 1.
Therefore, the top roll 4 has an annular groove part 42
which rolls the outside bottom surface of the hat shape
and flank parts 43 which are formed at the two sides of
10 the annular groove part 42 and roll the outside surfaces
of the hat shape and the bottom surfaces of the flanges
13. The inside surfaces of the annular groove part 42 are
also formed to face the side surfaces of the annular
barrel part 33 of the bottom roll 3 through a gap of the
15 amount of thickness of the hat-shaped steel 1. Due to
this, the annular groove part 42 of the top roll 4 varies
in cross-sectional shape in the circumferential
direction.
[0035] The side surfaces of the annular groove part 42
20 of the top roll 4, like the annular ridge part 33 of the
bottom roll 3, are formed with the region 43b which forms
the portion 11 of the hat-shaped steel 1; the regions 43c
and 43d which form the tapered portions 12a and 12b
respectively, and the region 43a which forms the portions
2 5 10a and lob, in the circumferential direction.
Furthermore, in the same way as the annular ridge part
33, the intermediate point which equally divides the
region 43a forms the start point of the rolls, and
therefore when assembling the top and bottom rolls 4 and
30 3 in the apparatus, the top and bottom rolls 4 and 3 are
positioned in the rotation direction at the positions
where their start points face each other (same phase).
[0036] If viewed in the shaft direction, the annular
ridge part 33 of the bottom roll 3 and the flank part 43
35 of the top roll 4 have cylindrical surfaces with outer
circumferential surfaces of the same diameters. Due to
this, if making the top and bottom rolls 4 and 3 rotate
by the same peripheral speeds, the relative phase of the
top and bottom rolls 4 and 3 will not change. In the case
of a pair of top and bottom rolls, so-called "slip" is
liable to cause the relative phase of the turning top and
5 bottom rolls 4 and 3 to change. If the rolls have crosssectional
shapes which are constant in the
circumferential direction, "slip" does not become that
much of a problem, but the top and bottom rolls 4 and 3
of the present embodiment have regions which vary in
10 cross-sectional shape in the circumferential direction,
and therefore if "slip" causes the top and bottom rolls 4
and 3 to become offset in phase, the finished product is
liable to become off in thickness from the design value
and the top and bottom rolls are liable to collide.
15 Therefore, in the present embodiment, it is important to
make the top and bottom rolls 4 and 3 turn without
changing their relative phases. The gear 52 which forms
the above-mentioned synchronized rotation mechanism also
has the role of preventing the relative phase of the
2 0 turning top and bottom rolls 4 and 3 from changing.
[0037] Note that, the top and bottom rolls 4 and 3
only have to be made from a material which is higher in
rigidity than the sheet or strip M at the roll barrel
parts. The material is not limited. Further, it is also
2 5 possible to arrange the rolling die which has the annular
ridge part at the top side and the rolling die which has
the annular groove part at the bottom side.
[0038] FIG. 3 shows a roll unit 20a which including
finishing rolls, but the other roll units 20b to 20k
3 0 which are arranged upstream of the finishing rolls may be
made the same in configuration as the roll unit 20a
except for the shapes of the rolls being different. For
this reason, detailed explanations of the other roll
units 20b to 20k will be omitted.
35 [0039] The present invention is not limited to the
following dimensions, but to further deepen
understanding, an example of the dimensions of the
different regions of the bottom roll 3 will be shown.
First, the radius of the bottom roll 3 to the outer
circumferential surface is 500 mm at the annular ridge
part 33 and 450 mm at the flank parts 32. The difference
5 of the two corresponds to the height of the hat shape.
The width of the outer circumferential surface of the
region 33a is 50 mm, while the arc length is 400 mm.
Further, the width of the outer circumferential surface
of the region 33b is 80 mm, while the arc length is 400
10 mm. Further, the portions 33c and 33d have arc lengths of
300 mm and expand in width or contract in width by a 15'
gradient angle. The top roll 4 faces the bottom roll 3
through a gap of 2 mm.
[0040] Next, the method of using the multistage roll
15 forming apparatus 2 to produce the hat-shaped steel 1
will be explained. First, the top and bottom rolls 4 and
3 of the roll units 20a to 20k are made to rotate at a
predetermined speed and the sheet or strip M is fed to
the roll unit 20k of the entry station. For example, as
2 0 the steel sheet or strip M, it is possible to use steel
sheet which is sent from an upstream rolling process or
use a strip which is wound in a coil shape. At this time,
the sheet or strip M is fed so that the length direction
becomes perpendicular to the axial direction of the top
2 5 and bottom rolls 4 and 3 and is roll formed in the length
direction of the sheet or strip M. The sheet or strip M
(intermediate) which is fed out from the roll unit 20k is
conveyed by the rotational operation of the top and
bottom rolls 4 and 3 to the roll unit 20j of the next
30 station. Further, it is roll formed by this second stage
roll unit 20j along the length direction and is further
conveyed to the roll unit 20i of the next station.
[0041] Note that, when continuously roll forming the
sheet or strip M, the roll units 20a to 20k of the
3 5 different stations may be used to form it while applying
back tension and/or forward tension. Further, they may
form it by cold, warm, or hot roll forming.
[0042] F I G S . 5A and 5B show the state where the sheet
or strip M is bent into a hat shape in stages at the 10
stages of the roll units 20a to 20k. F I G . 5A shows the
state in which the flanges 13 are formed by using the
5 roll units 20k to 20a at the first to fifth stations.
F I G . 5B shows the state in which the top wall of the hatshaped
steel 1 is formed by using the roll units 20e to
30a at the sixth to final stations. Note that, F I G S . 5A
and 58 are cross-sectional views of the portion 10a of
10 the hat-shaped steel 1, but the other portions lob, 11,
12a, and 12b are also bent in stages to the hat shape at
the 10 stages of the roll units 20a to 20k. Therefore,
the material (intermediate) which is roll formed at the
ninth station becomes a shape close to the final product
15 and is finally shaped by the 10th finishing roll.
[0043] The state where the finishing rolls perform the
final forming operation is shown in F I G . 6. In the sheet
or strip M (intermediate) which is conveyed from
upstream, the width L1 portion 10a is formed by the back
2 0 half part from the start point to the regions 33.3 and 43a
of the first top and bottom rolls, then the gradually
increasing width portion 12a is formed by the regions 33c
and 43c and, furthermore, the width L2 portion 11 is
formed by the regions 33b and 43b. Next, the gradually
25 decreasing width portion 12b is formed by the regions 33d
and 43d and finally the width Ll portion lob is formed by
the front half part from the start point of the regions
33a and 43a. At this time, the back half part of the
regions 33a and 43a forms the width L1 portion 10a of the
3 0 next product.
[0044] The finished product which is fed out from the
finishing roll after final shaping is completed is cut at
the position forming the terminating end (that is, the
end part of the portion lob) and, is conveyed to other
35 next step, for example, to the product inspection step.
The cutting position can be automatically discerned by
for example detecting a mark (for example, small hole,
projection, etc.) which is formed at intervals in the
length direction of the sheet or strip M, by a sensor.
The mark may be provided at intervals corresponding to
the lengths of the finished products at the sheet or
5 strip M in advance or may be provided during roll
forming. As the method of providing a mark during roll
forming, using top and bottom rolls 4 and 3 which are
formed with projections forming the mark at a position
corresponding to the starting point of the rolls so as to
10 transfer a mark along with bending to the hat shape may
be mentioned as one example. In addition to a mark, a
predetermined relief shape may be formed on the surface
of the roll barrel part so as to form a bead, embossing,
or other shape. FIGS. 7A and 7B show an example of a bead
15 14 and a projecting part 35 which is formed at a roll
barrel part for forming the bead 14. While not
illustrated, the top roll 4 is formed with a recessed
part which corresponds to the projecting part 35 though a
gap of the amount of thickness of the material. The
2 0 shapes, positions, and numbers of the beads and embossing
can be suitably changed.
roo451 According to the present embodiment, when using
a bottom roll 3 which has an annular ridge part 33 and a
top roll 4 which has an annular groove part which faces
25 the annular ridge part 33 to produce a hat-shaped steel
1, by the shapes of the annular ridge part 33 and the
annular groove part 42 being made shapes which vary in
cross-sectional shape in the circumferential direction, a
hat-shaped steel 1 which varies in cross-sectional shape
30 (that is, the hat shape) in the longitudinal direction
can be produced by simple control for making the top and
bottom rolls 4 and 3 rotate synchronized.
[0046] In this way, the roll forming according to the
present embodiment does not require the complicated
35 control method for changing the roll widths of split
rolls like in the past, and therefore does not require
the introduction of new control modules for this purpose.
Accordingly, for example, it is possible to realize the
roll forming apparatus of the present embodiment by
changing the rolls of an existing roll forming apparatus
to the top and bottom rolls 4 and 3 of the present
5 embodiment.
[0047] Note that, in the multistage roll forming
apparatus 2 of FIG. 2, the roll units 20a to 20k are
arranged on a line, but if arranging the roll units 20a
to 20k in tandem curved in the up-down direction, it
10 becomes possible to produce a hat-shaped steel which is
curved in the longitudinal direction.
[00481 Furthermore, according to the present
embodiment, by the roll barrel part which varies in
cross-sectional shape in the circumferential direction,
15 the roll barrel part and material can sufficiently
contact each other in the forming operation, and
therefore for example even if the material is high
tensile steel, insufficient mill rigidity can be
suppressed. Accordingly, the roll forming method and
2 0 apparatus of the present embodiment can also be applied
to tensile strength 980 MPa or more ultra high tensile
steel.
[0049]
Next, a modification of the rolling dies which are shown
25 in the above-mentioned first embodiment will be
explained. In the rolling dies of the present embodiment,
as shown in FIG. 8, the outside diameter of the annular
ridge part 33 of the bottom roll 3 (hatched part) and the
outside diameter of the bottom surface of the flank part
30 43 of the top roll 4 (hatched part) are the same, and the
side walls of the annular ridge part 33 of the bottom
roll 3 are provided with the later explained relief.
Leaving aside this feature, the top and bottom rolls 4
and 3 of the present embodiment are substantially the
35 same as the top and bottom rolls 4 and 3 of the first
embodiment. Similar component elements are assigned the
same reference notations, and detailed explanations are
omitted.
[0050] The relief which is provided at the side
surfaces of the ridge part 33 of the bottom roll 3 will
be explained in detail. FIG. 9 is a partial vertical
5 cross-sectional view which is cut along the plane which
includes the center axes of the top and bottom rolls 4
and 3. In the first embodiment, the gap between the
facing bottom surfaces and side surfaces of the top and
bottom rolls 4 and 3 was constant over the entire
10 circumference in the circumferential direction, but in
the present embodiment, the side surfaces of the annular
ridge part 33 of the bottom roll 3 are offset by the
relief amount x to the inside of the axial direction of
the roll from the inside surface of the designed hat-
15 shaped steel 1. By providing relief to the side surfaces
of the annular ridge part 33 in this way, the gap between
the side surfaces of the annular ridge part 33 and the
side surfaces of the annular groove part 42 becomes wider
the further toward the base of the annular ridge part 33,
2 0 that is, the inside in the radial direction. In the
figure, the broken line shows a side surface when not
providing the relief. In the case of the bottom roll 3 of
the final station, when working as one example a material
of a sheet thickness of 1.0 rnm, the relief amount x is
25 preferably 1.4 mm or more. The method of determination of
the relief amount will be explained later.
[0051] FIG. 10 shows the result of comparison of the
gaps between the top and bottom rolls 4 and 3 in the case
of relief and no relief. More specifically, FIG. 10 shows
3 0 the minimum distance (minimum gap) between the side
surfaces at the different phases when designating the
start points of the top and bottom rolls 4 and 3 (see
FIG. 4) as O0 and making the top and bottom rolls 4 and 3
rotate in 5" increments. As will be clear from FIG. 10, it
35 is learned that when not providing relief, the gap
greatly varies (decreases and increases) at the about 45'
to 65' region and the 100" to 120° region. FIGS. 11A and
11B show results of numerical analysis which show the
interference between rolls when not providing relief. The
parts which are shown by hatching show the interference
5 regions. The regions in which the gap varies correspond
to the transition parts 33c, 33d, 43c and 43d of the top
and bottom rolls 4 and 3.
[0052] On the other hand, it is learned that when
providing relief, the gap is varied in the transition
10 parts 33c, 33d, 43c and 43d, but the amount of variation
thereof is extremely small and the gap is maintained
substantially constant over Oo to 180' as a whole. While
depending on the thickness or shape of the shaped steel,
the preferable minimum gap when considering the product
15 specifications etc. becomes the thickness of the sheet or
more. According to the present embodiment, by providing
relief at the side surfaces of the annular ridge part 33
of the bottom roll 3, it becomes possible to secure a
minimum gap of the sheet thickness or more. Further, in
2 0 order to compare, FIG. 10 shows the gap in the case where
relief is provided only on the transition parts 33c and
33d and is not provided on the other regions. As will be
understood from FIG. 10, the gap cannot be maintained
constant by merely providing the relief only on the
2 5 transition parts 33c and 33d. In addition, providing the
relief only on the transition parts 33c and 33d has a
disadvantage in that it is more difficult than providing
the relief on all of the side surfaces.
[00531 The variation in the gap between the top and
30 bottom rolls 4 and 3 in the circumferential direction may
result in a variation in thickness of products.
Therefore, it is significantly advantageous that the gap
between the top and bottom rolls 4 and 3 in the
circumferential direction can be substantially constant
35 by providing a relief on the side surfaces of the annular
ridge part 33 of the bottom roll 3 so as to offset in the
axial inner direction of the roll. In addition, in the
case where the relief if provided on the annular ridge
part 33, in addition to enabling the gap to be maintained
substantially constant, the effect that a generation of
slip of the sheet on the side surface of the bottom roll
5 3 is suppressed to prevent generation of wrinkling, can
be obtained, and it is possible to prevent a reduction in
sheet thickness at the base region of the annular ridge
part 33, which prevents the sheet thickness from falling
below a fracture criteria. From the above, in the second
10 embodiment as well, it is possible to obtain effects
similar to the first embodiment and, furthermore, it is
possible to form a shaped steel which is kept down in
variation in sheet thickness.
[0054] Note that, it is preferable to provide relief
15 at the side surfaces of the annular ridge part 33 of the
bottom roll 3 not only at the roll unit 20a of the final
station, but also part or all of the other roll units 20b
to 20k which are arranged upstream of it. The multistage
roll forming apparatus 2 which is shown in FIG. 2 bends
2 0 the top wall of the hat-shaped steel 1 in five steps from
the sixth station to the final station (10th station),
and therefore it is preferable to provide relief at the
bottom rolls 3 of these stations.
100551 However, the top and bottom rolls 4 and 3 of
2 5 the stations differ in roll shape (in particular, the
inclination of the annular ridge part 33), and therefore
each of them has a preferable relief amount. Therefore,
the inventors etc. engaged in actual designs and
conducted intensive studies and as a result discovered
30 that the preferable relief amount x has a relationship
x=axHxtan8 with respect to the angle 8 of the side walls
of the shaped steel and the height H of annular ridge
part 33. In this regard, the relief amount x, the side
wall angle 8 of the shaped steel, and the height H of the
35 annular ridge part 33 are as shown in FIG. 13B. Referring
to FIG. 11, it will be understood that the actual relief
amount x is a value of HxtanO multiplied by the constant a
(a
FIG. 18A shows a hat-shaped steel 1 with a constant width
5 and height but with a cross-section which moves in the
lateral direction, while FIG. 18B shows the top and
bottom rolls 4 and 3 which form the hat-shaped steel 1 of
FIG. 18A by the final forming operation. That is, in the
above first embodiment, a hat-shaped steel with a
10 straight stock axis was produced, but in the present
embodiment, a hat-shaped steel 1 with a stock axis which
is curved in the width direction is produced. This hatshaped
steel 1 has portions 15a of a straight stock axis
and portions 15b of a curved stock axis. As the rolls for
15 this, as shown by the example in FIG. 18B, top and bottom
rolls 4 and 3 which have an annular ridge part and
annular groove part offset in the rotational axial
direction are used. The overall configuration of the roll
unit which drives rotation of the top and bottom rolls 4
2 0 and 3 can be configured in the same way as in the first
embodiment.
[0067] According to the present embodiment, by simple
control for making the top and bottom rolls rotate
synchronized, a hat-shaped steel with a cross-sectional
2 5 shape in the longitudinal direction which curves in the
width direction can be produced. Furthermore, if
arranging the roll units 20a to 20k in tandem curved in
the up-down direction, a hat-shaped steel which is curved
in the longitudinal direction can also be produced.
30 [0068]
FIG. 19A shows a hat-shaped steel 1 with a constant
height and a width in cross-sectional shape which varies
asymmetrically to the left and right, while FIG. 19B
shows the top and bottom rolls 4 and 3 which form the
35 final shape of the left-right asymmetric hat-shaped steel
1 which is shown in FIG. 19A. That is, in the present
embodiment, the top and bottom rolls 4 and 3 which are
shown in FIG. 18B are used to produce a hat-shaped steel
1 which has one side wall 10c of the hat shape which is
constant and has only the other side wall 10d changing in
the width direction. The overall structure of the roll
5 unit which drives rotation of the top and bottom rolls 4
and 3 can be configured in the same way as in the first
embodiment. In this case as well, by simple control for
making the top and bottom rolls 4 and 3 rotate
synchronized, a hat-shaped steel which varies
10 asymmetrically left and right in cross-sectional shape
width in the longitudinal direction can be produced.
[0069]
FIG. 20A shows a hat-shaped steel 1 with a constant
height and a complicated changing width in cross-
15 sectional shape, while FIG. 20B shows the top and bottom
rolls of the final station for the hat-shaped steel 1
which is shown in FIG. 20A. That is, in the present
embodiment, the top and bottom rolls 4 and 3 which are
shown in FIG. 20B are used to produce the hat-shaped
20 steel 1 which is further provided with portions of widths
different from L1 and L2. More specifically, the hatshaped
steel 1 of the present embodiment has straight
portions 16a and 16b and portions 16c to 16f which have
different widths. The overall structure of the roll unit
25 which drives rotation of the top and bottom rolls 4 and 3
can be configured in the same way as in the first
embodiment. In this case as well, by simple.contro1 for
making the top and bottom rolls 4 and 3 rotate
synchronized, a hat-shaped steel which varies
3 0 complicatedly in width of cross-sectional shape in the
longitudinal direction can be produced.
[0070]
In the present embodiment, a steel shape which forms a
cross-sectional U-shape is produced. FIG. 21A shows a U-
3 5 shaped steel 6 with a constant height and a changing
width in cross-sectional shape, while FIG. 21B shows the
top and bottom rolls 4 and 3 of the final station for the
U-shaped steel 1 which is shown in FIG. 21A. The U-shaped
steel 6 of the present embodiment has a constant height
and expanded width portion 61a and a constant height and
contracted width portion 61b. The rolling dies for this
5 include an annular ridge part of the bottom roll 3 with a
cross-sectional inverted U-shape which expands in width
in the circumferential direction in the range of 0" to
180" and contracts in width in the range of 180° to 360".
The annular groove part of the top roll 4 which faces the
10 bottom roll 3 also forms a U-shape which expands and
contracts in width in the circumferential direction. The
overall structure of the roll unit which drives rotation
of the top and bottom rolls 4 and 3 can be configured in
the same way as in the first embodiment. In this case as
15 well, by simple control for making the top and bottom
rolls 4 and 3 rotate synchronized, a U-shaped steel 6
which varies in cross-sectional shape width in the
longitudinal direction can be produced.
[00711
2 0 The U-shaped steel 6 of FIGS. 22A and 22B is
substantially the same as the U-shaped steel 6 of FIGS.
21A and 21B, except for being provided with the flanges
63. In this case as well, by simple control for making
the top and bottom rolls 4 and 3 rotate synchronized, a
25 U-shaped steel 6 which varies in cross-sectional shape
width in the longitudinal direction can be produced.
[00721
The present embodiment also produces shaped steel having
a U-shape cross-section. However, while the above-
30 mentioned fifth embodiment has a constant height, in the
present embodiment, as shown in FIG. 23A, a U-shaped
steel 6 with a constant width and a changing height is
produced. More specifically, the U-shaped steel 6 of the
present embodiment has a heightening portion 61c with a
35 constant width and a lowering portion 61d with a constant
width. FIG. 23B shows the top and bottom rolls 4 and 3 of
the final station for the U-shaped steel 6 which is shown
in FIG. 23A. The annular ridge part of the bottom roll 3
has a cross-sectional outer shape of an inverted U-shape,
expands in outside diameter in the circumferential
direction in the range of 0' to 180°, and contracts in
5 outside diameter in the range of 180° to 360'. The
recessed part of the top roll 4 which faces the bottom
roll 3 also has a U-shape which varies in height in the
circumferential direction. The overall structure of the
roll unit which drives rotation of the top and bottom
10 rolls 4 and 3 can be configured in the same way as in the
first embodiment. In this case as well, by simple control
for making the top and bottom rolls 4 and 3 rotate
synchronized, a U-shaped steel 6 which varies in crosssectional
shape height in the longitudinal direction can
15 be produced.
[0073]
Except for the point of the U-shaped steel 6 of FIGS. 24A
and 24B being provided with the flanges 63, this is
substantially the same as the U-shaped steel 6 of FIGS.
2 0 22A and 228. In this case as well, by simple control for
making the top and bottom rolls 4 and 3 rotate
synchronized, a U-shaped steel 6 which varies in crosssectional
shape width in the longitudinal direction can
be produced.
2 5 [0074]
The present embodiment produces a shaped steel which
forms a cross-sectional V-shape. FIG. 25A shows a Vshaped
steel 7 with a width in cross-sectional shape
which is constant and a height which varies, while FIG.
30 25B shows the top and bottom rolls 4 and 3 of the final
station for the V-shaped steel 7 which is shown in FIG
30A. More specifically, the V-shaped steel 7 of the
present embodiment has a heightening portion 71a with a
constant width and a lowering portion 71b with a constant
35 width. The annular ridge part of the bottom roll 3 has a
cross-sectional outer shape of a triangular shape (Vshape)
and an expanding outside diameter in the
circumferential direction in the range of 0' to 180' and
decreasing outside diameter in the range of 180' to 360".
The recessed part of the top roll 4 which faces the
bottom roll 3 also becomes a triangular shape (V-shape)
5 which varies in height in the circumferential direction.
The roll unit which drives rotation of the top and bottom
rolls 4 and 3 can be configured in overall structure in
the same way as in the first embodiment. In this case as
well, by simple control for making the top and bottom
10 rolls 4 and 3 rotate synchronized, a V-shaped steel 7
which varies in height in cross-sectional shape in the
longitudinal direction can be produced.
[0075] <11th Embodiment>
FIG. 26A shows a hat-shaped steel 1 which varies in both
15 width and height of cross-sectional shape, while FIG. 26B
shows the top and bottom rolls 4 and 3 of the final
station for the shape of the hat-shaped steel 1 which is
shown in FIG. 26A. More specifically, the hat-shaped
steel 1 of the present embodiment has a portion 17a of a
2 0 cross-sectional shape width L1 and height hl, a portion
17b of a cross-sectional shape width L2 and height h2,
and a portion 17c of a changing width L1 to L2 and height
hl to h2. For this reason, the annular ridge part and
annular groove part of the top and bottom rolls 4 and 3
25 are made shapes which vary in both height and width of
cross-sectional shape in the circumferential direction
(Ll+L2+Ll, hl+h2+hl). The overall structure of the roll
unit which drives rotation of the top and bottom rolls 4
and 3 can be configured in the same way as in the first
30 embodiment. In this case as well, by simple control for
making the top and bottom rolls 4 and 3 rotate
synchronized, a hat-shaped steel 1 which varies in both
width and height in cross-sectional shape can be
produced.
35 [0076] Above, the present invention was explained in
detail with reference to specific embodiments, but
various substitutions, alterations, changes, etc.
relating to the format or details are possible without
departing from the spirit and scope of the invention such
as defined by the language in the claims will be clear to
5 a person having ordinary skill in the technical field.
Therefore, the scope of the present invention is not
limited to the above-mentioned embodiment and attached
figures and should be determined based on the description
of the claims and equivalents to the same.
10
Reference Notations List
[0077] 1 hat-shaped steel
2 multistage roll forming apparatus
3 bottom roll
15 32 flank part
33 annular ridge part
4 top roll
42 annular groove part
43 flank part
CLAIMS
Claim 1. A method of producing a shaped steel which
varies in cross-sectional shape in the longitudinal
direction from a sheet by roll forming, comprsing:
5 a step of preparing a first rolling die which
has a rotation shaft and an annular ridge part which
varies in cross-sectional shape in a circumferential
direction which is centered about said rotation shaft;
a step of arranging said first rolling die so
10 that the rotation shaft of said first rolling die becomes
perpendicular to a sheet feed direction;
a step of preparing a second rolling die which
has a rotation shaft and an annular groove part which
varies in cross-sectional shape in a circumferential
15 direction which is centered about said rotation shaft;
a step of arranging said second rolling die so
that a gap which is equal to a thickness of said sheet is
formed between said first rolling die and second rolling
die and the annular ridge part of said first rolling die
2 0 and the annular groove part of said second rolling die
engage;
a step of making said first rolling die and
said second rolling die rotate synchronized; and
a step of feeding a sheet between said first
2 5 rolling die and second rolling die,
wherein the side surfaces of the annular ridge
part of said first rolling die are provided with relief
so that the gap with respect to side surfaces of the
annular groove part of the second rolling die broadens
30 inward in the radial direction throughout the
circumference.
Claim 2. The method of production of a shaped steel
according to claim 1, wherein the width measured in the
rotation shaft direction of each of said annular ridge
35 part of the first rolling die and said annular groove
part of the second rolling die varies in the
circumferential direction.
Claim 3. The method of production of a shaped steel
according to claim 1 or 2, wherein each of said annular
ridge part of said first rolling die and said annular
groove part of said second rolling die is configured so
5 that a height which is measured in a perpendicular
direction with respect to said rotation shaft varyies in
the circumferential direction.
Claim 4. The method of production of a shaped steel
according to any one of claims 1 to 3, wherein said
10 shaped steel is a hat-shaped steel with an inner
circumferential surface which is rolled by the annular
ridge part of the first rolling die and with an outer
circumferential surface which is rolled by the annular
groove part of the second rolling die.
15 Claim 5. The method of production of a shaped steel
according to any one of claims 1 to 4, wherein the ridged
portion of said first rolling die includes, in its
circumferential direction, a first roll width region, a
second roll width region, and a tapered region which
20 increases or decreases in width from said first roll
width to second roll width.
Claim 6. The method of production of a shaped steel
according to any one of claims 1 to 4, wherein said first
rolling die has an annular ridge part which is offset in
2 5 the rotation shaft direction in its circumferential
direction and produces a shaped steel having stock axis
which is curved in the width direction.
Claim 7. The method of production of a shaped steel
according to claim 1, wherein the relief amount x of the
3 0 side surfaces of said first rolling die is set to not
less than a value which is calculated by the equation:
x=axH xtan8 (a is a constant determined based on a roll
shape), where a height of the annular ridge part is "H",
an angle of the side walls of the shaped steel is "0"
35 (8<85") .
Claim 8. The method of production of a shaped steel
according to claim 7, wherein a plurality of roll units
each of which comprises first rolling dies and second
rolling dies are arranged in series in a sheet feed
direction and the material is bent by these plurality of
5 roll units so that the side wall angle 8 (note that,
8<85') is increased in stages, and in that the relief
amount x of the side surfaces of the first rolling die of
part or all of the roll units is not less than a value
which is calculated by the equation: x=ctxH xtan8.
10 Claim 9. The method of production of a shaped steel
according to any one of claims 6 to 8, wherein an outside
diameter of the annular ridge part of said first rolling
die and an outside diameter of the bottom surface part of
the grooved part of the second rolling die are the same.
15 Claim 10. The method of production of a shaped steel
according to any one of claims 1 to 10, wherein the
material is ultra high tensile steel.
Claim 11. A roll forming apparatus for roll forming
for producing a shaped steel which varies in cross-
sectional shape in the longitudinal direction from a
sheet, comprising:
a first rolling die which has a rotation shaft
and an annular ridge part which varies in cross-sectional
shape in a circumferential direction which is centered
about said rotation shaft, said first rolling die
arranged so that the rotation shaft of said first rolling
die becomes perpendicular to a sheet feed direction;
a second rolling die which has a rotation shaft
and an annular groove part which varies in cross-
sectional shape in a circumferential direction which is
centered about said rotation shaft, said second rolling
die arranged so that said rotation shaft of said second
rolling die becomes parallel to said rotation shaft of
said first rolling die; and
a drive device which synchronizes and
rotationally drives said first rolling die and said
second rolling die,
wherein said first rolling die and second
rolling die are arranged relatively so that a gap which
is equal to a thickness of said sheet is formed between
the two and the annular ridge part of said first rolling
die and the annular groove part of said second rolling
die engage,
wherein the side surfaces of the annular ridge
part of said first rolling die are provided with relief
so that the gap with respect to side surfaces of the
annular groove part of the second rolling die broadens
inward in the radial direction throughout the
circumference.