DESCRIPT]ON
TITLE OF INVENTION
METHOD FOR PRODUCINC METAL SHEET WITH RAISED LINES, METAL
SHEET WITH RAISED LINES, AND STRUCTURAL COMPONENT
TECHNICAL F'IELD
[000 r ]
The present invention relates to a metal sheet such as a steel sheet suited to be
used in structural components of automobiles, various kinds of vehicles other than
automobiles, home appliances, vessels, construction materials and so on. In particular,
the present invention relates to a metal sheet inchlding, on each of the upper surface
and the lower surface, one or more raised lines extending in the rolling direction, a
method for producing the rnetal sheet with raised lines, and a structural component
produced by Lrse of the metal sheet with raised lines.
BACKGROUND ART
[0002]
Pressed parts are used in general structural components. The material of a
pressed part is a metal sheet such as a steel sheet. A structural component is formed
from a single pressed part or fonned by joining a plurality of pressed parts. For
exatnple, the structural components for automobiles disclosed in Japanese Patent
Application Publication No.20l3-189173 (Paf.ent Literature l) and Japanese Patent
Application Publication No. 2014-91462 (Palent Literature 2) each include a
verlically-long pressed part. The cross section of the pressed part is U-shaped.
[0003]
FIGS. lA and 1B show an example of a structural component. Of these
drawings, FlG. 1A is a perspective view of the structural component, and FIG. lB is a
cross-sectional view of an end pottion of the structural component illustrated in FIG.
lA. The structural component 20 illustrated in FIGS. I A and I B includes two
pressed parts 21, each having a U-shaped cross section. Each of the pressed parts 2l
includes a plate portion 24 and flanges 22 extending from the both sides of the plate
portion 24. By welding the flanges 22 of the two pressed parts 21 together, the
structural component 20 in the shape of a square-pipe is obtained. Reinforcing plates
40 are welcled to the back side of the two plate poftions 24 and four ridge portions 23
of the structural component20, at both end portions in the longitudinal direction. In
this case, however, the strength of the structural component20 is increased only at
both end portions in the longitudinal direction. Therefore, it can be considered that
the reinforcement of the structural cornponent 20 is not sufficient.
[0004]
In order to produce a partly-reinforced structural component such as the
structural component 20 illustrated in FIGS. I A and 18, it is necessary to weld the
reinforcing plates 40 to the portions that need to be reinforced. Accordingly, a
welding process must be separately carried out to partly reinforce the structural
component 20, which results in an increase in manufacturing cost.
CITAITON LIST
PATENT LITERATURE
[000s]
Patent Literature I : Japanese Patent Application Publication No. 2013- I 891 73
Patent Literature 2: Japanese Patent Application Publication No.20l4-91462
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0006]
The present invention has been made in view of the above circumstances.
An object of the present invention is to provide a production method that, in producing
a partly-reinforced structural component, facilitates the production of a metal sheet
with raised lines suitable as a lnaterial for the structural component. In addition,
another object of the present invention is to provide a metal sheet with raised lines
suited to be used forthe production of the structuralcomponent, and astructural
component using the metal sheet with raised lines.
SOLUTION TO PROBLEM
[0007]
( I ) A rnetal sheet production method according to an embodiment of the
present invention is a method for producing a rnetal sheet by use of a rolling mill
including a rollstand, the rnetalsheet including, on each of an upper surface and a
lower surface, one or firore raised lines extending in a rollirig direction. The
production method includes a preparing step, an incorporating step, and a forming step.
In the preparing step, grooved rolls are prepared, each of the grooved rolls including,
in an outer peripheral surface, one or rnore grooves extending in a circumferential
direction. In the incorporating step, the grooved rolls are incorporated in the roll
stand as an upper roll and a lower roll, respectively.
In the forming step, a workpiece is rolled by the rolling mill incorporating the grooved
rolls, thereby fonning the workpiece into a metal sheet with raised lines forrned
corresponding to the respective grooves ofthe grooved rolls.
[0008]
ln the prodLrction method (l), it is preferred that, in a longitudinalsection of
each of the grooved rolls, the grooves are in a bilaterally symmetric arrangement.
[000e]
In the production method (l), the grooves rnay be arranged such that, in
longitudinal sections of the respective grooved rolls, the arrangement of the grooves of
the grooved roll incorporated as the upper roll and the arrangement of the grooves of
the grooved roll incorporated as the lower roll do not overlap at least partly.
[00 r 0]
In the prodLrction method (l), in a longitudinalsection of each of the grooved
rolls, each of the grooves may be rectangular,trapezoidal or V-shaped.
[00r r ]
In the production method (1), each of the grooves of the grooved rolls rnay
have a width more than 5 mm and less than 2000 mm.
[001 2]
In the production method (1), the grooves of the grooved rolls rnay be at a
pitch more than l5 mm and less than 2000 mm.
[00 r 3]
(2) A rnetal sheet with raised lines according to an embodiment of the present
invention is a metal sheet including one or rnore raised Iines on each of an upper
surface and a lower surface. The raised lines are at a pitch more than I 5 mm and less
than 2000 mm. A sheet thickness ratio (t / tmin) of a raised-line sheet thickness t to a
minimum sheet thickness tmin is more than I .0 and less than 1 0.0, the raised-line sheet
thickness t being expressed by a sum of the minimum sheet thickness trnin and a height
h of the raised lines.
[00 r4]
In the metalsheet with raised lines (2), each of the raised lines rnay have a
width more than 5 mm and less than 2000 mm.
[00rs]
(3) A structural component according to an embodiment of the present
invention including one or more raised lines on each of a front side and a back side.
The structural component includes a reinforced porlion that is increased in strength,
and the raised lines are disposed on the front side and the back side ofthe reinforced
portion.
ADVANTACEOUS EFFECTS OF INVENTION
[001 6]
The production method according to the present invention facilitates the
production of a metal sheet with raised lines. The metal sheet with raised lines
includes, on each of an upper surface and a lower surface, one or more raised lines
extending in a rolling direction. Accordingly, using the rnetal sheet with raised lines
as a material to produce a partly-reinforced structural component allows for production
of a structural component including a reinforced portion that is reinforced in the entire
area. Thus, the metal sheet with raised lines according to the present invention is
suitable as a material for a partly-reinforced structural component.
BRIEF DESCRIPTION OF DRAWINGS
[00 r 7]
[FIG. I A] FIG. I A is a perspective view of an example of a structural component.
IFIG. I B] FIG. I B is a cross-sectional view of an end portion of the structural
component illustrated in FlG. 14.
IFIG. 2] FIG. 2 is a schematic diagrarn of an example of a production facility usecl for
the production of a metal sheet with raised lines according to an embodiment of the
present invention.
IFIG. 3] FIG. 3 is a cross-sectional view of an example of a roll stand incorporating
grooved rolls according to the embodiment of the present invention.
IFIG. 4] FIG. 4 is a perspective view of a metal sheet with raised lines produced by a
finish-rolling rnill including the roll stand illustrated in FIG. 3.
IFIG. 5] FIG. 5 is a schematic cross-sectional view of an example of a metal sheet with
raised lines.
[FIG. 6] FIG. 6 is a schernatic cross-sectional view of an example of a metal sheet with
raised lines.
tFIG. 7] FIG. 7 is a schematic cross-sectional view of an exampie of a rnetal sheet with
raised lines.
[FIG. 8] FIC. I is a schematic cross-sectional view of an example of a metalsheet with
raised lines.
IFIG. 9] FIG. 9 is a graph showing an exanrple of warping occurring in a roll stand
incorporating grooved ro I ls.
IFIG. I 0] FIG. 10 is a cross-sectional view of an example of a blank cut out from a
metal sheet with raised lines to be used for the production of a structural component
according to an embodiment of the present invention.
[FIG, I 1A] FIG. 1 I A is a schematic cross-sectional view of an example of an apparatus
for pressing the blank illustrated in FIG. 10 into a structural component.
IFIG. ll B] FIG. I lB is a cross-sectional view of a pressed part fonned by the
apparatus illustrated in FIG. l1A.
[FIG. 124] FIG, 1 2A is a schematic cross-sectional view of another example of an
apparatus for pressing the blank illustrated in FIG. l0 into a structural component.
IFIG. 128] FIG. 128 is a cross-sectional view of a pressed part fonned by the
apparatus illustrated in FIG. 124.
[FIG. 13] FIG. 13 is a schematic view of an example of a structural component.
[FIG. 14] FIG, l4 is a schematic view of an example of a structural component.
IFIG. 1 5] FIG. 1 5 is a schernatic view of an example of a structural component.
[FIG. I 6] FIG. l6 is a schematic view of an example of a structural component.
[FlG. 1 7] FIG. I 7 is a schematic view of an example of a structural component.
IFIG. 18] FIG. 18 is a schematic view of an example of a stnlctural component.
IFIC. I 9] FIC. 19 is a schematic view of an example of a structural cornponent.
[FIG. 20] FIG. 20 is a schematic view of an example of a structural component.
[FIG. 21] FIG. 21 is a schematic view of an example of a structural component.
IFIG . 221 FlG. 22 is a schematic v iew of an example of a structural component.
DESCRIPTION OF EMBODIMENTS
[00 r 8]
Sorne embodiments of the present invention will hereinafter be described with
reference to the drawings.
[00 re]
[Producing of Metal Sheet with Raised Lines]
FIG. 2 is a schematic diagram of an example of a production facility used for
the production of a metal sheet with raised lines according to an embodiment of the
present invention. The present embodiment describes the production of a steel sheet
l0 with raised Iines as an example of the production of a metal sheet with raised lines.
Specifically, in the following, the production of a metalsheet with raised lines with a
steel slab 30 used as a material for the metal sheet with raised lines will be described.
[0020]
The production facility illustrated in FIG. 2 includes a heating furnace 1, a
rough-rolling rnill 2, a finish-rolling rnill 3, a cooling device 4, and a coiler 5 that are
arranged in this order. The heating furnace I heats the slab 30. The heated slab 30
is first fed to the rough-rolling mill 2. The rough-rolling rnill 2 rolls the slab 30 to
form the slab 30 into a longer-length steel plate 3l having a thickness of, for exarnple,
about 50 mm. The steel plate 3l is fed to the finish-rolling mill 3. The finishrollingmill
3 includes arow of six rollstands S1 to S6 (which may hereinafter be
referred to as simply "stands"). The steel plate 3l is rolled while passing through the
stands Sl to 56 successively, whereby the steel plate 3l is formed into a steel sheet 10
having a desired thickness. Thus, the steel plate 31 is a workpiece to be rolled by the
finish-rolling mill 3. The steel sheet l0 is cooled while passing through the cooling
device 4, and is wound up into a coil by the coiler 5.
[0021]
Each of the stands Sl to S6 of the finish-rolling mill3 includes an upper roll 6
and a lower roll 7 (work rolls), and further includes back-up rolls paired with the rolls
6 andl respectively. Each of the stands Sl to S6 is provided with an inter-roll-axis
distance adjustrnent mechanism (not shown in the drawings). The inter-roll-axis
distance adjustment mechanism adjusts the distance between the axis of the upper roll
6 and the axis of tlie lower roll 7. The inter-roll-axis distance adjustment mechanism
allows for adjustrnent of the rolling recluction achieved by the upper roll 6 and the
lower roll 7 in each of the stands Sl to 56.
100221
Each of the stands Sl to 56 is provided with a load cell(not shown in the
drawings), The load cell measures the rolling load applied by the upper roll 6 and the
lower roll 7. The load cell allows for monitoring of the rolling load in each of the
stands S I to S6. The load cell also al.lows for detection of a time point at which the
leading edge of the steel plate 3l reaches each of the stands S1 to 56 (a time point at
which the leading edge of the steel plate 3 1 is pinched in a gap between the upper roll
6 and the lower roll 7).
[0023]
Howeveq in a case where any of the stands Sl to 56 does not perfonn to roll
the steel plate 31, no rolling load occurs in the non-rolling-performing stand. In this
case, detection as to whether the leading edge of the steel plate 3 t has reached the nonrolling-
performingstand can be carried out by use of the outputfrol¡ the load cell
provided in a rolling-performing stand that is one stage before the non-rollingperforming
stand. Specifically, the load cell detects the leading edge of the steel plate
3l reaching the rolling-performing stand, and an elapsed time from a time point of the
detection is measured. Based on the elapsed time, a theoretical running speed of the
workpiece due to rolling by the rolling-performing stand, and a distance between a roll
axis of the rolling-performing stand and a roll axis of the next nori-rolling-performing
stand, it is possible to calculate the time point at which the leading edge of the steel
plate 3l has reached the non- rolling-performing stand. However, each of the stands
Sl toS6rnaybeprovidedwithasensorthatdetectspassingoftheleadingedgeofthe
steel plate 3 1.
100241
In the present ernbodiment, in order to produce the steel sheet i0 with raised
lines, grooved rolls, which willbe described later, are incorporated in one specified roll
stand that is selected from amongthe roll stands Sl to S6 of the finish-rollingmill 3.
The specified stand is chosen according to rolling capabilities (e.g., rolling loads,
rolling reductions, etc.) of the stands Sl to 56. For example, in the finish-rolling rnill
3 illustrated in FIG. 2, the foufth stand 54, which is two stages before the last sixth
stand 56, incorporates the grooved rolls. There is no particular limit to the stand to
incorporate the grooved rolls. One or more stands in stages subsequent to the stand
including the grooved rolls incorporated therein each serve as a notr-rolling-perfonning
stand, which does not substantially roll, and rolls incorporated in the non-rollingperforming
stand function as rolls for conveyance.
[002s]
FIG. 3 is a cross-sectional view of an example of a roll stand incorporating
grooved rolls according to the embodiment of the present invention. FIG. 4 is a
perspective view of a rnetalsheetwith raised lines produced bythe fìnish-rolling mill
including the roll stand illustrated in FIG. 3. In the present embodiment, as shown in
FIG. 3, grooved rolls I are incorporatecl in as the upper roll 6 and the lower roll 7 of
tlie specifìed stand (the foLrlth stand 54 illustrated in FIG. 2). ln the stands other than
the specified stand, normal flat rolls are incorporated.
100261
In the outer peripheral surface of each of the grooved rolls 8, one or more
grooves 9 (hereirrafter, also referred to as "roll grooves") are made to extend in the
circumferential direction. The grooved roll 8 used as tlie upper roll 6 shown in FIG. 3
has two roll grooves 9 in each end porlion. The grooved roll 8 used as the lower roll
7 shown in FIG. 3 has two roll grooves 9 in the central portion. The steel plate 3l is
rolled by the finish-rolling rnill 3 including these grooved rolls 8. Thereby, raised
lines I I are fonned corresponding to the respective roll grooves 9, and a steel sheet 10
with raisecl lines ll is prodLrced (see FIG.4). The raised lines ll extend in the rolling
direction of the steelsheet 10. As shown in FIGS. 3 and4, since the grooved rolls 8
are incorporated in as the upper roll 6 and the lower roll 7, the raised lines 1l are
fonned on both the upper surface and the lower surface ofthe steel sheet 10.
100211
In longitudinalsections of the grooved rolls 8, each of the roll grooves 9 is
rectangular, trapezoidal or V-shaped. Here, being rectangtlar,trapezoidal or Vshaped
inclucles being in a shape varying a little from these shapes and in a combined
shape ofcurved lines.
[0028]
It is preferred that, in a longitudinalsection of each of the grooved rolls 8, the
arrangement of the rollgrooves 9 is bilaterally symmetric as shown in FIG. 3. Here,
bilaterally mearls in adirection alongthe axial direction of the grooved rolls 8 and in a
width dilection that is perpendicular to the rolling direction of the steelsheet 10. If
the arrangement of the roll grooves 9 is bilaterally asymmetric, the rolling performed
by the grooved rolls 8 will be bilaterally uneven. ln this case, the steelslieet l0 is
likely to rnove obliquely, and trouble may occllr during operation. On the other hand,
when the arrangementof the roll groo';es 9 is bilaterally symrnetric, the rolling
perfonned by the grooved rolls 8 is bilaterally even. Then, the steelsheet 10 moves
straight in the rolling direction, and any trouble due to oblique movement of the steel
sheet l0 will not occur during operation.
l002el
The rollgrooves 9 rnay be arranged such that, in lorrgitudinalsections of the
respective grooved rolls 8, the arrangernent of the rollgrooves 9 of the grooved roll 8
incorporated as the upper roll6 and the arrangernent of the roll grooves 9 of the
grooved roll 8 incorporated as the lower roll 7 do not overlap at all as shown in FIG. 3
or do not overlap partly. Alternatively, the roll grooves 9 may be arranged such that,
in longitudinal sections of the respective grooved rolls 8, the arrangement of the roll
grooves 9 of the upper roll 6 and the arrangement of the roll grooves 9 of the lower roll
7 wholly overlap.
[0030]
The width w1 of the rollgrooves 9 corresponds to the width of the raised lines
I I of the steel sheet I 0. The pitch of the roll grooves 9 corresponds to the pitcli p of
the raised lines I I of the steel sheet 1 0. The depth of the roll grooves 9 corresponds
to the height h ofthe raised lines I I ofthe steel sheet I 0. In the steel sheet 10, the
portiott with the minimum sheet thickness tmin is formed by the rolling of the portion
10
of the grooved roll with no roll grooves 9 (the portion hereinafter referred to as "nongrooved
poÍion") and the flat rolls. The minimum sheet thickness tmin of the steel
sheet l0 is the minimum sheet thickness of the portion with no raised lines 11. The
width w2 of tlre non-grooved porlion corresponds to the width of a recessed portion l2
between two adjacent raised lines I I (the recessed portion hereinafter referred to as
"inter-raised-line recessed portion"). Tlie dimensions regarding the roll grooves 9 and
the raised lines 11 (including the numbers and the cross-sectional shapes of these
members 9 and 1 I ) are determined basically by the designed dimensions of a structural
component (pressed part) to be produced by use of the steelsheet 10 with raised lines.
The determination is made in consideration of the capability of the fÌnish-rollingmill 3,
the effective length of the roll (practically 2000 rnm atrnost) and so on. Further, the
deterrnination is made in consideration of the fonnability of the steel sheet 10 with
raised lines into the pressed part,
1003 rl
For example, the width wi of the roll grooves 9 (that is, the width of the
raised lines 1 l) can be set to a value more than 5 mm and less than 2000 mm, In this
regard, however, the width of the roll grooves 9 is desirably equal to or greater than I 0
tnm, and more desirably equal to or greater than 20 mrn. This is to secure a sufficient
width for a reinforced portion of a structural component to be produced by use of the
steel sheet l0 with raised lines, thereby ensuring the strength of the structural
component. Also, the width of the rollgrooves 9 is desirably equalto or less than
1000 rnm, and more desirably equalto or less than 500 mm. This is to reduce the
weight of a structural component to be produced by use of the steel sheet 1 0 with
raised lines,
[0032]
The pitch of the rollgrooves 9 (that is, the pitch p of the raised lines ll) can
be set to a value more than l5 mm and less than 2000 mln. In this regard, however,
the pitch of the roll grooves 9 is desirably nìore than 20 mm. This is to ensure the
width w1 of the rollgrooves 9 (that is, the width of the raised lines 11), thereby
ensuringthe strength of astructuralcomponentto be produced by use of the steel sheet
l0 with raised lines. Also, the pitch of the rollgrooves 9 is desirably equalto or less
than 500 mm, and more desirably equal to or less than 200 mm. The reason is as
11
follows. If the pitch of the rollgrooves 9 is too large, in a case where the width of the
roll grooves 9 (that is, the width of the raised lines 1l) is small, the width w2 of the
non-grooved portion (that is, the width of the inter-raised-line recessed porlion 12) will
be large. Then, the portion with the minimum sheet thickness tlnin of the steel sheet
l0 will have a large width. In this case, the portion witlr the minimum sheet thickness
tmin willdeform easily, and the qLrality of the steelsheet 10 will be degraded.
[0033]
The sheet thickness ratio (t / tmin) of the raised line sheet tliickness t (trnin +
h), which is the sum of the minimum sheet thickness tmin of the steelsheet 10 and the
height h of the raised lines 11 (that is, the depth of the roll grooves 9), to the minimum
sheet thickness tmin can be set to a value more than i.0 and less-than I0.0. In this
regard, however, the sheet thickness ratio (t / tmin) is desirably equal to or more than
1.2. This is to ensure the height h of the raised lines 11, thereby ensuring the strength
of a structural component to be produoed by use of the steel sheet 10 with raised lines.
Also, the sheet thickness ratio (t / trnin) is desirably less than 4.0, If the sheet
thickness ratio (t / tmin) is too large, the rolling reduction achieved by the grooved
rolls 8 will be excessively large.
[0034]
There is no particular limitto the minimunr sheetthickness tmin of the steel
sheet 10. However, the minirnum sheet thickness trnin is practically about 0.6 to 10
mm.
[003s]
FIGS. 5 to I are schematic cross-sectional views of other examples of a metal
sheet with raised lines. Each of the steelsheets l0 illustrated in FIGS. 5 to 7 includes,
on each of the upper surface and the lower surface, a plurality of raised lines 1 1 . The
steelsheet 10 illLlstrated in FIG.8 inclLrdes one raised line on the uppersurface and a
plurality of raised lines on the lower surface. In any of FIGS. 5,6 and 8, the raised
lines are in a bilateral syrnrnetric arrangement, and in FIG. 7, the raised lines are in a
bi Iateral ly asymmetric arrangement.
[0036]
For example, when the steel plate 3 I is rolled by a fìnish-rolling mill 3
including a grooved roll 8 incorporated as the upper roll 6 of the specified stand (the
12
fourlh stand 54 illustrated in FIG. 2) and a flat roll incorporated as the lower roll 7 of
the specified stand, the following trouble will occur, and the process to produce a steel
sheet with raised lines will not go srnoothly. Lr the specified stand, the steel plate 31
immediately after subjected to the rolling by tlie rolls is more likely to stick to the
grooved roll 8 as the upper roll 6 than to stick to the flat roll as the lower roll 7, This
is because the steel plate 3l gets stuck in the roll grooves 9. This provides upward
force to the steel plate 3l that has passed through the specified stand. Therefore, if
the maximum rolling recluction achieved by the rolls of the specified stand is initially
settoareqLriredvalue,theleadingendportionofthesteel plate3l willwarpupward
greatly. The greatly warping leading end portion of the steel plate 3l will wind
around the grooved roll 8 or collide against the next stand without corning into the gap
between the rolls of the stancl.
[003 7]
To cleal with such a trouble in operation, in the present embodiment, grooved
rolls 8 are incorporated in the specified stancl as both the upper roll 6 and the lower roll
1 . Then, in the specified stand, the steel plate 31 irnmediately after subjected to the
rolling by the rolls stick to the grooved roll 8 as the lower roll 7 as well as to the
grooved roll I as the upper roll 6. Thereby, the upward force acting on the leading
end portion of the steel plate 31 is reduced until the leading edge of the steel plate 31
reaches the stand next to the specified stand. Thus, warping of the leading end
portion of the steel plate 3 I is suppressecl, and the leading edge of the steel plate 3 1
smoothly cornes into the gap between the rolls of the next stand. Therefore, even
when the maximum rolling reduction achieved by the rolls of the specified stand is
initially set to a required value, any trouble due to warping of the leading end portion
of the steel plate 3 1 will not occur. Also, it is possible to produce a desired steel sheet
10 with raised lines from the beginning, and the yield is good.
[003 8]
The maximum rolling reduction A herein is expressed by the following
Formula ( 1).
A:(t0-tt)lt0xr00[%] ...(l)
In the Fonnula (1), t0 denotes the sheet thickness of the steel plate 3l before
subjected to the rolling in the specified stand, ancl tl denotes the minimum sheet
13
thickness of the inter-raised-line recessed porlion 12 in the steelsheet l0 after
subjected to the rolling in the specified stand.
The setting and adjustrnent of the maximur¡ rolling reduction are carried out
by the inter-roll-axis distance adjustrnent mechanism provided for the specified stand.
[003e]
In consideration of the capability of the finish-rolling mill 3, the required
valueasthemaximurnrollingreductionofthespecifiedstandispreferably I0to80%,
More preferably, the required value is 20 f.o 60 o/0.
100401
FIG. 9 shows an example of warping occurring in the roll stand including
grooved rolls. An analysis model including grooved rolls in the specified stand as the
upper roll and the lower roll as shown in FIG. 2 was produced as an inventive example,
and a FEM analysis was perfonned on the assumption of an early stage of hot rolling.
Also, an analysis model including a grooved roll in the specifìed stand as the upper roll
was produced as a conrparative exar.nple, and a FEM analysis was perfonned in the
salïe way. For analysis of each of the models, the temperature of the workpiece to be
rolled was assumed to be 1100'C, and the coefficient of friction p between the rolland
the workpiece was assumed to be 0.1. The maximum rolling reduction achieved by
the upper and the lower rolls was 15 Yo. The displacements of the leading edge of the
rolled workpiece in the vertical direction at various points distant horizontally from the
center position between the axis of the upper roll and the axis of the lower rollwere
examined.
[004 r]
The results shown in FIG. 9 show the following. The displacements of the
leading edge of the rolled workpiece in the vertical direction of the inventive example
were small, as compared with those of the comparative example. This shows that
incorporating grooved rolls in the specified stand as both the upper roll and the lower
roll as in the present embodiment suppresses warping of the leading end portion of the
steel plate.
10042)
IProduction of StructuralComponent (Pressed Part) by use of Metal Sheet with Raised
Linesl
14
The above-clescribed steel sheet l0 with raised lines is usecl as a blank for a
structural conlpouent to be produced by press working. At the tirne of production of a
structural colnponent, the steel sheet l0 is cut into a shape fit for a pressed part to be
used in the structural component. Before cutting, the steel sheet 10 is subjected to
hot-dip galvanizing, hot-dip galvannealing, electrogalvanizing, aluminum plating or
the like. Before such a plating process, the oxidized film on the surface of the steel
sheet l0 is removed by pickling, shot blasting or the like. The pickling, the shot
blasting, and the plating only need to be performed before the press working, and these
processes may be perfonned toward the blank cut out from the steel sheet I 0.
Depending on the specification of the structural component, the plating may be omitted.
[0043]
FIG. l0 is a cross-sectional view of an example of a blank cut out from a
metal sheet with raised lines to be used for the production of a structural component
according to an ernbodiment of the present invention. FICS. I lA and ll B are
sectional views schematically showing an example of pressing to form the blauk
illustrated in FIG. l0 into a structural component. FIG. llA shows a pressing
machine, and FIG. I 1B shows a pressed part for a structural component. FIGS. 124
and 128 show another example of pressing of the blank illustrated in FIG. 10 into a
structural component. FIG. 124 shows a pressing machine, and FIG. 128 shows a
pressed part for a structural component. The present embodiment describes a case
where the above-described steel sheet l0 with raised lines is used as the metal sheet
with raised lines as an example.
[0044]
As shown in FIG. 10, a blank 15 is cut out from the steelsheet 10. In this
regard, the steel sheet 10 is cut along the longitudinal direction (the extending direction
of the raised lines 11) and along the lateral direction (direction perpendicular to the
extending direction of the raised lines 1l). The cut position is determined depending
on the specification of the structural component.
[004s]
For example, the pressed paft2l shown in FIG. 118 and FIG. 128 has a Ushaped
cross section. By joining two pressed parts 21, a structural component in the
shape of a square pipe is producecl (see FIGS, I A and I B). In the pressed part 2l , the
15
portion that needs to have strength is a porlion from the plate portion 24 to the ridge
portions 23. Therefore, when the blank I5 fit for the pressed paft2l is cut out from
the steel sheet I 0, the steel sheet i 0 is cut at the inter-raised-line recessed portions I 2
such that one of the raised lines 11 can be formed into the plate portion 24 andthe
ridge portions 23 of the pressed par12l.
[0046]
As shown in FIG. 1lA, the bank l5 can be pressed into the pressed partZl by
use of a sirnple set of a punch 5 I and a die 52. In this case, however, as shown in FIG.
1 I B, since the raised line 1 I with a greater sheet thickness is bent, spring-back is likely
to occllr. Therefore, it is preferred that a segmented punch 53 is used as illustrated in
FIG. l2A. In the segmented punch 53, a shoulder portion is separated. At the time
of pressing, by applying a greater load to the raised line 11 from the shoulder portion
of the punch 53, it is possible to suppress the spring-back.
100471
FIGS. l3 to 17 are schematic views showing other examples of structural
cornporrents. Any of the structural components 20 (pressed pafts2l) illustrated in
FIGS. I 3 to 17 is formed from the blank 15 cut out frorn the above-described steel
sheet l0 with raised lines, and has one or more raised lines 1l on the front side or on
the back side. These structural components formed from a steel sheet with raised
lines have the following advantages over structural components formed from a steel
sheet having an even sheet thickness: of having high performance as a structural
component; and of being produced in a simple rnethod. For example, no separate
reinforcing member is necessary, thereby resulting in a reduction in the number of
members. Integration of a reinforcing member into a structural component allows for
improvements in strength and rigidity and a reduction in weight, Integration of a
reinforcing member also eliminates the need to carry out a jointing process by welding,
screwing and the like. Fufther, such a structural component including an integrated
reinforcing member has a smaller overall surface area than a structural component
including a separate reinforcing tnernber, and thus, integration of a reinforcing member
also results in an irnprovelnent in antirust capability.
[0048]
The structural component20 illustrated in FIG. i3 has an L-shaped cross
16
section, and has a raised line l1 on the back side of the ridge porlion 23. In this case,
the ridge porlion 23 is reinforced throLrghout the whole length, and the strength of the
structural component 20 is irnproved.
[004e]
The structural component 20 illLrstrated in FIG. I 4 is substantially planar, and
has a wide raised line I I on the front side, in the center. In this case, the central
portion is reinforced over a wide range throughout the whole length, and the strength
of the structural component 20 is irnproved.
[00s0]
The structural component 20 illustrated in FIC. l5 has a U-shaped cross
section, and has a raised line I I on the back side of the ridge portions 23 and the plate
portion 24. In this case, the plate portion 24 and the ridge portions 23 are reinforced
throughout the whole length, and the strength of the structural component 20 is
inrproved. Further, by locating tlre raisecl line I I at a distance frorn the axis of
bending (neutral axis), it is possible to minimize an increase in weight, thereby
resLrlting in a great enhancernent of the second moment of area.
[00s l]
The structural component 20 illLrstratecl in FIG. 16 has a U-shaped cross
section, and has raised lines I I on the back side ofthe portions near the ridge portions
23. In this case, the portions of the plate portion 24 near the ridge portions 23 and the
portions of the flange s 22 near the ridge portions 23 are reinforced throughout the
whole length, and the strength of the structural component20 is improved. With
regard to the structural component 20 shown in FIG. 16, not the raised lines l1 but the
portions near the raised lines ll is bent at the time of press working, and the
forrnability is good. Specifically, the steel sheet with raised lines has in-plane
anisotropy because of the presetrce of raised lines. Utilization of this characteristic
allows for both a reduction in the pressing load at the time of press working and
enhancelnents of the pressed part in strength and rigidity.
[00s2]
The structural componetrt 20 illustrated in FlG. 17 is shaped like a square pipe.
This structural component 20 is a cornbination of a pressed parl having a U-shaped
cross sectiolr and a metal sheet. In the square-pipe-like structural component 20, the
17
raised lines ll are arranged to extend in the circumferential direction. Accordingly,
the inter-raised-line recessed portion l2 extends in the circumferential direction of the
square-pipe-like stnrctural component 20. ln this case, the pofiions whele the raised
lines I I are located are reinforced throughout the whole circumference, and the
strength of the structural component 20 is irnproved. Therefore, even if another
component is welded to any of the portions where the raised lines il are located, the
structural component 20 maintains strength. Accordingly, the structural component
20 is effectively Lrsed as a component required to be welded to another component.
The structural component 20 is effectively used especially as a welded component of
which thickening is restricted for the reason of constraints on weight and space. With
regard to the structural component20 illustrated in FIG. l7,the portion where the
inter-raised-line recessed portion l2 is located is fragile throughout the whole
circumference. Accordingly, the poftion where the inter-raised-line recessed portion
l2 is located is more breakable than the portions where the raised lines 11 are located.
Therefore, the structural component 20 is effectively Lrsed as a component of which
breakdown region is intentionally specitìed.
[00s3]
FIGS. 18 to 22 are schematic views of other examples of structural
components. Any of the structural components 20 (pressed parts 21) illustrated in
FIGS. 1 8 to 22 is formed from a blank l5 cut ont from the above-described steel sheet
l0 with raised lines, and has one or more raised lines 11 on each of the front side and
on the back side. The intended purposes of use of the structuralcomponents 20
illustrated in FIGS. l8 f.o 22 are the sarne as those of the structural components 20
illustrated in FICS. 13 to 17.
[00s4]
In the above'described embodiment, the steel sheet 10 with raised lines is
produced by hot working by use of the finish-rolling mill 3. Therefore, in the thick
portions where the raised lines I 1 are located, the cooling rate is slow, and the hardness
is likely to become low, as compared with those in the other portions (the inter-raisedline
recessed porlions l2). Utilizingthis characteristic of the raised lines ll, it is
possible to improve the formability by using the portions where the raised lines 1 I are
located as the portions of a structural cornponent to be shaped with difficulty.
18
[00ss]
TABLE I below shows examples of a strength difference between a portion
where a raised line is located and another portion. As is clear from TABLE i, the
strength difference varies depending on the material of the workpiece (whether highcarbon
steel or low-carbon steel), the difference between the raised-line sheet thickness
and the minimum sheet thickness, the cooling rate and the like, The portion where
the raised line is located always has higher hardness than any other porlion.
[00s6]
ITABLE 1]
TABLts
Tes t
No.
Mater i a l
Raised-line
shee t
thickness
Imm]
Minimum
sheet
th i cknes s
Imm]
Cool ing
raLe
["c/sec]
Stee I
sheet
runn i ng
speed
Im/min]
Strength
d i fference
h¡pal
A
Hiehcarbon
steel
1A 1,0 40 350 282
u
[,ow-carbon
sLeel
3.0 1.0 25 350 144
C
lli ehcarbon
steel
3.0 2.0 50 330 255
D
f-ow-carbon
steel 3.2 2.0 20 280 54
E
Hi ehcarbon
stee I
3.8 1.0 50 330 391
F
Low-carbon
steel 3.5 1.0 20 330 211
[00s7]
As thus far described, the metal sheet production method according to the
present embodiment facilitates the production of a metal sheet with raised lines. The
metal sheet with raised lines has, on each of the upper surface and the lower surface,
one or more raised Iines extending in the rolling direction. Accordingly, when the
metal sheet is used as a material for a partly-reinforced structural component, it is
possible to obtain a structural component including a reinforced portion that is
19
reinforced in the entire area. Thus, the metal sheet with raised lines is suited to be
used as a material for a partly-reinforced structural component. The use of the metal
sheet with raised lines eliminates the need to weld a separate reinforcing plate to partly
reinforce the structural component. This allows for a reduction in manufacturing cost
[00s8]
The present invention is not limited to the above-described embodirnent, and
various changes are possible without departing from the gist and scope of the present
invention. For exarnple, the metal sheet with raised lines, the r-naterial of the rnetal
sheet, the material of the structuralcomporrent formed from the metalsheet are not
limited to steel, such as ordinary carbon steel, high-tensile steel, stainless steel and the
like, and aluminum, copper and the like rnay be used. In the rolling rnill including
grooved rolls, the total number of stands is not lirnited.
[005e]
The method for pressing a blank cut out from the metal sheet with raised lines
into a structural component is not particr.rlarly limited. As the method, for example, it
is possible to adopt a hot stamping rnethod in which forming and quenching are carried
or-rt in a mold.
LIST OF REFERENCE SYMBOLS
[0060]
1: heating furnace
2: rough-rolling mill
3: finish-rolling rnill
4: cooling device
5: coiler
Sl to 56: roll stand
6: upper roll
7: lower roll
8: grooved roll
9: groove
I 0: steel sheet
ll:raisedline
I 2: inter-raised-line recessed portion
1 5: blank
20: structural component
21: pressed part
22: flange
23: ridge porlion
24: plate portion
30: slab
3 l: steel sheet
5 1 : punch
52: die
53: segmented punch
w1: width of roll groove
w2: width of non-grooved portion
p: pitch of raised lines
trnin: minimum sheet thickness
h : he ight of raisecl I ine
t: raised-line sheet thickness

We claim:
1. A rrethod for prodLtcing a metalsheet by use ola lolling rnill including a roll
stand, the metal sheet including, on each of an upper surface and a lower surface, one
or more raised lines extending in a rolling direction, the method corlplising:
a preparing step of preparirrg grooved rolls, each of the glooved rolls
including, in an outer peripheral sLrrface, otle or more grooves extending in a
circurnfelential d i rection;
an incorporating step of incorporating the grooved rolls in tlie roll stand as an
upper roll and a lower roll, respectively;
a foruring step of rolling a workpiece by the rolling mill incorporating the
grooved rolls, thereby forming the workpiece into a metal sheet with raised lines
formed corresponding to the respective grooves of the grooved rolls.
2. The method for producing a metal sheet with raised lines according to claim 1,
wherein
in a longitudinal section of each of the grooved rolls, the grooves are in a
b ilateral ly symmetric amaltgerreltt.
3. The method for producing a rnetal sheet with raised lines according to claim
1 or 2, wherein
the grooves are arranged such that, in longitudinal sections ofthe respective
grooved rolls, the arrangement of the grooves of the grooved roll incorporated as the
upper roll and the arrangement of the grooves of the grooved roll incorporated as the
lower roll clo not overlap at least partly.
4. The methocl for proclircing a metal sheet with raisecl Iines according to any one
of claiurs I to 3, wllerein
in a longitudinalsection of each of the grooved rolls, each of the grooves is
rectangu lar, trapezoidal or V-shaped.
5. The rnethod f'or producing a metal sheet with raised lines according to any one
22
of claims I to 4, wherein
each of the grooves of the grooved lolls has awidth more than 5 rnm and less
than 2000 rnnl.
6. The method for producing a metal sheet with raised lines accordirrg to any one
of claims I to 5, wherein
the grooves of the grooved rolls ale at a pitch rnore than l5 mrn a¡d less than
2000 mm.
7. A rnetal sheet with raised lines, the rnetal sheet comprising, on each of an
upper surface and a lower surface, one or more raisecl lines, wherein:
the raised lines are at a pitch more than r 5 mm and less than 2000 mm; and
a sheet thickness ratio (t / trnin) of a raised line sheet thickness t to a minimum
sheet thickness tmin is more than 1.0 and less than I 0.0, the raised line sheet thickness
being expressed by a sum of the minimum sheet thickness tmin and a height h of the
raised lines.
8. The nletal sheet with raised lines according to claim T, wherein
each of the raised lines has a width more than 5 mnr and less tlran 2000 mm.
9' A structural component comprising one or more raised lines on each of a front
side and a back side, wherein
the structural component includes a reinforced portion that is increased in
strength, and the raised lines are disposed on the front side and the back side ofthe
reinforced portion