SPECIFICATION
PRESS-FORMING METHOD OF COMPONENT WITH L SHAPE
Technical Field
[0001]
The present invention relates to a press-forming method of a component with an
L shape used as a framework member or the like of an automobile.
The present application claims priority on Japanese Patent Application No.
2010-115208, filed in Japan on May 19, 2010, the contents of which are cited herein by
reference.
Description of Related Art
[0002]
An automobile framework structure is formed by joining framework members
such as a front pillar reinforcement, a center pillar reinforcement, or a side sill outer
reinforcement manufactured by press-forming a blank metal sheet. For example, FIG. 1
shows a framework structure 100 formed by joining framework members 110, 120, 130,
and 140 by spot welding. The framework member 110 has an L shape including a top
sheet section 111, a vertical wall section 112, and a flange section 113, thereby ensuring
strength and rigidity of the framework structure 100.
[0003]
In general, when a component having an L shape (hereinafter, sometimes called
an L-shaped component) such as the framework member 110 is press-formed, a drawing
method is employed in order to suppress generation of wrinkles. In the drawing method,
as shown in (a) and (b) of FIG 3, a blank metal sheet 300A is drawn into a formed body
300B by using a die 201, a punch 202, and a blank holder 203 (holder). For example,
when a component 300 shown in FIG 4A is manufactured by the drawing method, (1) the
blank metal sheet 300A shown in FIG. 4B is disposed between the die 201 and the punch
202, (2) a clamped area Tin the periphery of the blank metal sheet 300A shown in FIG. 4C
is strongly clamped by the blank holder 203 and the die 201, (3) the blank metal sheet
300A is drawn formed into a drawn body 300B shown in FIG 4D by relatively moving the
die 201 and the punch 202 in a press direction (vertical direction), and (4) unnecessary
portions of the periphery of the drawn body 300B are trimmed, thereby obtaining the
component 300. By this drawing method, a flow of a metal material of the blank metal
sheet 300A can be controlled by the blank holder 203, and therefore generation of
wrinkles due to an excessive inflow of the blank metal sheet 300A can be suppressed.
However, since a large trim area is needed in the periphery of the blank metal sheet 300A,
the yield is reduced, resulting in an increase in costs. In addition, during the drawing, in
the drawn body 300B, as shown in FIG. 5, wrinkles are more likely to be generated in an
area (a area) into which the metal material excessively flows, and cracks are more likely
to be generated in an area ((3 area) in which the thickness is locally reduced. In order to
prevent such cracks and wrinkles, typically, a metal sheet having excellent ductility and
relatively low strength needs to be used as the blank metal sheet 300A.
[0004]
As described above, a blank metal sheet to be drawn requires high ductility. For
example, when a steel sheet having small ductility and high strength is used as the blank
metal sheet to draw an L-shaped component, cracks or wrinles are likely to be generated
due to insufficient ductility. Accordingly, typically, the L-shaped component such as a
front pillar reinforcement or a center pillar reinforcement is manufactured using a steel
sheet having excellent ductility and relatively low strength as the blank metal sheet.
Therefore, in order to ensure strength, the thickness of the blank metal sheet needs to be
high, so that there is a problem with increases in component weight and costs. Such a
problem also occurs when a framework member 110' having a T shape is press-formed by
combining two L shapes as shown in FIG. 2.
[0005]
In Patent Documents 1 to 4, bend-forming methods for manufacturing
components having simple cross-sectional shapes such as a hat shape or a Z shape are
described . However, such methods cannot be used for manufacturing the L-shaped
component.
[Related Art Documents]
[Patent Documents]
[0006]
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No.
2003-103306
[Patent Document 2] Japanese Unexamined Patent Application, First Publication No.
2004-154859
[Patent Document 3] Japanese Unexamined Patent Application, First Publication No.
2006-015404
[Patent Document 4] Japanese Unexamined Patent Application, First Publication No.
2008-307557
[Disclosure of the Invention]
[Problems to be Solved by the Invention]
[0007]
In consideration of the problem, an object of the present invention is to provide a
press-forming method of a component with an L shape, the method being capable of
press-forming a component with an L shape from a blank metal sheet with high yield even
though a high-tensile material with low ductility and high strength is used for the blank
metal sheet.
[Means for Solving the Problems]
[0008]
In order to accomplish the object, the invention uses the following methods.
(1) A first aspect of the present invention is a forming method that forms a press
component with an L shape from a blank metal sheet, the press component having a top
sheet section and a vertical wall section which is connected to the top sheet section via a
bent section having a part curved in an arc shape and which has a flange section on an
opposite side to the bent section, the top sheet section being arranged on an outside of the
are of the vertical wall section, the method including: disposing the blank metal sheet
between a die amd both of a pad and a bending die; and forming the vertical wall section
and the flange section while at least a part of the blank metal sheet is caused to slide on a
part of the die corresponding to the top sheet section, the forming of the vertical wall
section and the flange section being performed in a state where the pad is made close to or
brought into contact with the blank metal sheet.
(2) In the forming method described in (1), in the forming of the vertical wall
section and the flange section, a part of the metal sheet may be pressurized as an
out-of-plane deformation suppressing area by the pad.
(3) In the forming method described in (1), in the forming of the vertical wall
section and the flange section, a portion of the metal sheet that is made close to or brought
into contact with an out-of-plane suppressing area of the pad as the out-of-plane
deformation suppressing area may be formed in a state where a clearance between the pad
and the die is equal to or larger than a thickness of the blank metal sheet and is maintained
to be equal to or smaller than 1.1 times the thickness of the blank metal sheet.
(4) In the forming method described in (2) or (3), the out-of-plane deformation
suppressing area may be, among areas of the top sheet section divided by a tangent line of
a boundary line between the bent section and the top sheet section, the tangent line being
defined at a first end portion which is one end portion of the part curved in the are shape
of the bent section when viewed in a direction perpendicular to a surface of the top sheet
section, an area of the blank metal sheet which contacts with the part of the die
corresponding to the top sheet section on a side including a second end portion which is
other end portion of the part curved in the arc shape of the bent section.
(5) In the forming method described in any one of (2) to (4), in the end portion of
the blank: metal sheet, among portions of the part of the blank metal sheet corresponding
to the out-of-plane deformation suppressing area, a portion which becomes the end portion
of the part further on the top sheet side than the bent section may be on the same plane as
that of the top sheet section.
(6) In the forming method described in any one of (1) to (5), the top sheet section
may have an L shape, a T shape, or a Y shape.
(7) In the forming method described in any one of (1) to (6), a height of the
vertical wall section may be equal to or larger than 0.2 times a length of the part curved in
the arc shape of the bent section, or equal to or larger than 20 mm.
(8) In the forming method described in any one of (1) to (7), the forming of the
vertical wall section and the flange section may be performed so that the pad is made close
to or brought into contact with a region of the blank metal sheet; and the region of the
blank metal sheet may be, among portions of the top sheet section, a portion which is in
contact with a boundary line between the top sheet section and the part curved in the are
shape of the bent section, and which is within at least 5 mm from the boundary line.
(9) In the forming method described in any one of (4) to (8), in the flange section,
in a portion of the vertical wall section connected to the part curved in the are shape of the
bent section, widths of a flange portion of the first end portion side from a center portion
in a longitudinal direction of the flange of the portion connected to the opposite side to the
top sheet section and a flange portion in front of the flange portion of the first end portion
side by 50 mm or larger may be equal to or larger than 25 mm and equal to or smaller than
100 mm.
(10) In the forming method described in any one of (1) to (9), a radius of
curvature of a maximum curvature portion of the boundary line between the part curved in
the are shape of the bent section and the top sheet section may be equal to or larger than 5
mm and equal to or smaller than 300 mm.
(11) In the forming method described in any one of (1) to (10), a pre-processed
blank metal sheet may be press-formed as the blank metal sheet.
(12) In the forming method described in any one of (1) to (11), a blank metal
sheet having a breaking strength of equal to or higher than 400 MPa and equal to or lower
than 1,600 MPa may be used as the blank metal sheet.
(13) A second aspect of the present invention is a forming method of a press
component having an L shape, including: performing forming by the forming method
according to any one of claims 1 to 12 to form a shape of a single L character, a shape of a
plurality of L characters, or a shape of any L character, when a shape having a plurality of
L characters is press-formed.
(14) A third aspect of the present invention is a forming method of a press
component having an L shape, for forming an L shape which has a vertical wall section, a
flange section connected to one end portion of the vertical wall section, and a top sheet
section that is connected to an end portion of the vertical wall section on the opposite side
to a side connected to the flange section and extends in the opposite direction to the flange
section and in which a part or the entirety of the vertical wall section is curved so that the
flange section is on the inside, by pressing a blank metal sheet, including: performing
forming by disposing a blank metal sheet having a shape in which an end portion of a part
of the blank metal sheet corresponding to a lower side of the L shape is inside the top
sheet section, on a die, and pressing the vertical wall section and the flange section with a
bending die while pressing the top sheet section with a pad.
(15) In the forming method described in (14), a width of the flange section on the
upper side from the center of the curve of the vertical wall section may be equal to or
larger than 25 mm and equal to or smaller than 100 mm.
(16) A fourth aspect of the present invention is a forming method of a press
component having an L shape, for forming an L shape which has a vertical wall section, a
flange section connected to one end portion of the vertical wall section, and a top sheet
section that is connected to an end portion of the vertical wall section on the opposite side
to a side connected to the flange section and extends in the opposite direction to the flange
section and in which a part or the entirety of the vertical wall section is curved so that the
flange section is on the inside, by pressing a blank metal sheet, including: disposing the
blank metal sheet having a shape in which an end portion of a part of the blank metal sheet
corresponding to the lower side of the L shape is inside the top sheet section, a margin
thickness is provided in the flange section on the upper side from the center of the curve of
the vertical wall section, and the sum of the thickness of the flange section and the margin
thickness is equal to or larger than 25 mm and equal to or smaller than 100 mm, on a die;
performing forming by pressing the vertical wall section and the flange section with a
bending die while pressing the top sheet section with a pad; and trimming the margin
thickness of the flange section.
(17) In the forming method described in (16), a radius of curvature of a maximum
curvature portion of the curve of the vertical wall section may be equal to or larger than 5
mm and equal to or smaller than 300 mm.
(18) In the forming method described in (16) or (17), a pre-processed blank metal
sheet may be press-formed as the blank metal sheet.
(19) In the forming method described in any one of (16) to (18), a steel sheet
having a breaking strength of equal to or higher than 400 MPa and equal to or lower than
1,600, MPa may be used as the blank metal sheet.
(20) A fifth aspect of the present invention is a forming method of a press
component having an L shape, including: performing forming by the forming method
according to any one of claims 16 to 19 to form a shape of a single L character, a shape of
a plurality of L characters, or a shape of any L character, when a shape having a plurality
of L characters is press-formed.
[Effects of the Invention]
[0009]
According to the invention, when the component with the L shape (L-shaped
component) _is press-formed from the blank metal sheet, a part of the blank metal sheet
corresponding to the lower side portion of the L shape of the L-shaped component is
drawn toward the vertical wall section. As a result, in the flange section in which cracks
are more likely to be generated due to a reduction in the thickness of the sheet during
typical drawing, excessive drawing of the member is reduced, so that generation of cracks
is suppressed. In addition, in the top sheet section in which wrinkles are more likely to
be generated due to an inflow of an excessive metal material during typical drawing, the
member is drawn, so that generation of wrinkles is suppressed.
[0010]
In addition, since a large trim area for blank holding does not need to be provided
in the part of the blank metal sheet corresponding to the lower side portion of the L shape
of the L-shaped component, unlike a typical forming method, the area of the blank metal
sheet can be reduced, thereby increasing the yield. Moreover, since ductility needed by
the blank metal sheet for forming is reduced, in addition to a steel sheet which has
excellent ductility and relatively low strength and is thus typically used, a steel sheet
having relatively low ductility and high strength can be used as the blank metal sheet.
Accordingly, the thickness of the blank metal sheet can be reduced, thereby contributing to
a reduction in weight of the automobile.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
FIG. 1 is a perspective view showing a framework structure 100 including a
framework member 110 having an L shape.
FIG. 2 is a perspective view showing a framework member 110' having a T shape.
FIG. 3 is an explanatory view of a drawing method.
FIG. 4A is a perspective view showing a component 300 obtained by the drawing
method.
FIG. 4B is a perspective view showing a blank metal sheet 300A which is to be
formed into the component 300.
FIG. 4C is a perspective view showing a clamped area Tin the periphery of the
blank metal sheet 300A.
FIG. 4D is a perspective view showing a formed body 300B obtained by drawing
the blank metal sheet 300A.
FIG. 5 is a perspective view showing a portions in which wrinkles are more likely
to be generated and R portions in which cracks are more likely to be generated in the
formed body 300B.
FIG. 6 is a perspective view of an L-shaped component 10 obtained by a press
component forming method according to an embodiment of the invention.
FIG. 7 is a schematic diagram of a die unit 50 used for the press component
forming method according to the embodiment of the invention.
FIG. 8 is a schematic view showing a press forming process performed by the die
unit 50 used in the press component forming method according to the embodiment of the
invention.
FIG. 9A is a diagram showing a steel sheet S used in the press component forming
method according to the embodiment of the invention.
FIG. 9B is a perspective view showing a state where the steel sheet S is disposed
on a die 51.
FIG. 9C is a perspective view showing a state where the steel sheet S is formed
into the L-shaped component 10.
FIG. 10 is a diagram showing an out-of-plane deformation suppressing area (area
F) of the steel sheet S as a hatched section.
FIG 11 is a diagram for explaining formed bodies in Examples I to 3 and 41 to
52.
FIG. 12 is a diagram for explaining a formed body in Example 4.
FIG. 13 is a diagram for explaining a formed body in Example 5.
FIG 14 is a diagram for explaining a formed body in Example 6.
FIG. 15 is a diagram for explaining a formed body in Example 7.
FIG. 16 is a diagram for explaining a formed body in Example 8.
FIG. 17 is a diagram for explaining a formed body in Example 9.
FIG. 18 is a diagram for explaining a formed body in Example 10.
FIG 19 is a diagram for explaining a formed body in Example 11.
FIG. 20 is a diagram for explaining a formed body in Example 12.
FIG 21 is a diagram for explaining a formed body in Example 13.
FIG. 22 is a diagram for explaining formed bodies in Examples 14 to 17.
FIG. 23 is a diagram for explaining formed bodies in Examples 18 to 20.
FIG. 24 is a diagram for explaining a formed body in Example 21.
10
FIG 25 is a diagram for explaining a formed body in Example 22.
FIG. 26 is a diagram for explaining a formed body in Example 23.
FIG. 27 is a diagram for explaining formed bodies in Examples 24 to 28.
FIG. 28 is a diagram for explaining formed bodies in Examples 29 to 32.
FIG 29 is a diagram for explaining formed bodies in Examples 33 to 36.
FIG. 30 is a diagram for explaining formed bodies in Examples 37 to 38.
FIG 31 is a diagram for explaining a formed body in Example 39.
FIG 32 is a diagram for explaining a formed body in Example 40.
FIG. 33 is a diagram showing the shape of a pre-processed metal sheet used in
Examples 37 and 38.
DETAILED DESCRIPTION OF THE INVENTION
[0012]
Hereinafter, a press-forming method according to an embodiment of the invention
will be described in detail.
[0013]
In the press-forming method according to this embodiment, a component having
a top sheet section 11 and a vertical wall section 12 which is connected to the top sheet
section 11 with a bent section 15 having a part 15a curved in an arc shape and has a flange
section 13 on the opposite side to the bent section 15, is formed from a steel sheet (a blank
metal sheet). The top sheet section 11 exists on the outside of the arc of the vertical wall
section 12.'_ In this press-forming method, the vertical wall section 12 and the flange
section 13 are formed while at least a part of the area of the steel sheet S (at least a part of
the area of the steel sheet S corresponding to the top sheet section 11) is allowed to slide
(in-plane movement) on a part of a die 51 corresponding to the top sheet section 11.
More specifically, the steel sheet S is disposed between the die 51 and both of a pad 52
and a bending die 53, and in a state where the pad 52 is made close to or brought into
contact with the steel sheet S, the vertical wall section 12 and the flange section 13 are
formed while at least a part of the steel sheet S is caused to slide on the part of the die 51
11
corresponding to the top sheet section 11.
In addition, "a state where the pad is made close to the steel sheet" means a state
where the steel sheet and the pad do not come in contact with each other when the steel
sheet slides on the part of the die corresponding to the top sheet section, and the steel sheet
and the pad come in contact with each other when the steel sheet is likely to undergo
out-of-plane deformation (or buckling) on the corresponding part.
[0014]
During forming of the vertical wall section 12 and the flange section 13, a part of
a metal sheet S may be pressurized as an out-of-plane deformation suppressing area (area
F) at a predetermined load pressure by the pad 52.
[0015]
For example, when a pad load pressure is set to be high and thus "the portion that
abuts on the top of the die 51" of the steel sheet S cannot sufficiently slide (perform
in-plane movement) between the die 51 and the pad 52 during pressing, cracks are
generated in the flange section 13.
In addition, when the load pressure by the pad 52 is set to be low and thus
out-of-plane deformation of "the portion that abuts on the top of the die 51" of the steel
sheet S cannot be restrained during pressing, wrinkles are generated in thetop sheet
section 11.
When a metal sheet which is generally used for automobile components and the
like and has a tensile strength of 200 MPa to 1,600 MPa is formed, when the metal sheet is
pressured at apressure of equal to or higher than 30 MPa, cracks are generated in the
flange section 13. On the other hand, when the metal sheet is pressurized at a pressure of
equal to or lower than 0.1 MPa, out-of-plane deformation of the top sheet section 11
cannot be sufficiently suppressed. Therefore, it is preferable that pressurizing by the pad
52 be performed at a pressure of equal to or higher than 0.1 MPa and equal to or lower
than 30 MPa.
Moreover, in consideration of a pressing machine or a die unit for manufacturing
general automobile components, since a load is low at a pressure of equal to or lower than
12
0.4 MPa, it is difficult to stably pressurize the pad 52 using a cushion gas. In addition, at
a pressure of equal to or larger than 15 MPa, a high-pressure pressurizing apparatus is
needed, and thus equipment costs are increased. Therefore, it is more preferable that
pressurizing by the pad 52 be performed at a pressure of equal to or higher than 0.4 MPa
and equal to or lower than 15 MPa.
The pressure mentioned herein is an average surface pressure obtained by
dividing a pad pressurizing force by the area of the contact portion of the pad 52 and the
steel sheet S, and may be slightly locally uneven.
[0016]
In addition, during forming of the vertical wall section 12 and the flange section
13, the forming may be performed in a state where, as an out-of-plane deformation
suppressing area (the area F), a portion of the steel sheet S that is made close to or brought
into contact with an out-of-plane deformation suppressing area of a pad maintains a
clearance between the pad 52 and the die 51. Here, the clearance may be equal to or
larger than the thickness of the steel sheet S and equal to or smaller than 1.1 times the
thickness of the steel sheet S.
[0017]
For example, when the portion corresponding to the top sheet section 1 I is
formed in the state where the clearance between the pad 52 and the die 51 is equal to or
larger than the thickness of the steel sheet S and is maintained to be equal to or smaller
than 1.1 times the thickness thereof, the steel sheet S can sufficiently slide (perform
in-plane movement) in the die unit 50 since an excessive surface pressure is not applied to
the sheet S. Moreover, when a surplus thickness is provided in the top sheet section 11
as the forming proceeds and thus a force to cause the steel sheet S to undergo out-of-plane
deformation is exerted, out-of-plane deformation of the steel sheet S is restrained by the
pad 52, so that generation of cracks or wrinkles can be suppressed.
When the portion corresponding to the top sheet section 11 is formed by setting
the clearance between the pad 52 and the die 51 to be smaller than the thickness of the
steel sheet S, an excessive surface pressure is exerted between the steel sheet S and the die
13
51, and thus the steel sheet S cannot sufficiently slide (perform in-plane movement) in the
die unit 50 and cracks are generated in the flange section 13.
On the.other hand, when the portion corresponding to the top sheet section 11 is
formed by setting the clearance between the pad 52 and the die 51 to be equal to or larger
than 1.1 times the thickness of the steel sheet S, out-of-plane deformation of the steel sheet
S cannot be sufficiently strained during pressing, so that the steel sheet S is significantly
left at the top sheet section 11 as the forming proceeds. Therefore, in addition to the
generation of significant wrinkles, buckling occurs in the top sheet section 11, so that the
portion cannot be formed into a 'predetermined shape.
With regard to a portion of the metal sheet which is generally used for automobile
components and the like and has a tensile strength of 200 MPa to 1,600 MPa, the portion
being close to or brought into in contact with the out-of-plane suppressing area of the pad
52 as the out-of-plane deformation suppressing area (the area F), when the portion is
formed in the state where the clearance between the pad 52 and the die 51 is equal to or
larger than the thickness of the sheet and is maintained to be equal to or smaller than 1.1
times the thickness of the sheet, small winkles are generated if the clearance between, the
pad 52 and the die 51 is equal to or larger than 1.03 times the. thickness of the sheet.
Therefore, it is more preferable that the clearance between the pad 52 and the die 51 be
equal to or larger than the thickness of the sheet and equal to or smaller than 1.03 times
the thickness of the sheet.
[0018]
Specifically, in the press-forming method according to this embodiment, as
shown in (a) and (b) of FIG. 8, when a steel sheet S is pressed to be formed into an L shape
which has the vertical wall section 12, the flange section 13 connected to the vertical wall
12 with the one end portion, and the top sheet section 11 connected to an end portion of
the vertical wall section 12 on the opposite side to the side connected to the flange section
13 and extends in the opposite direction to the flange section 13, and which is curved so
that a part or the entirety of the vertical wall becomes the inside of the flange section 13,
the steel sheet S having a shape in which an end portion of a part of the steel sheet S
14
corresponding to the lower side of the L shape of the steel sheet S is inside the top sheet
section I1 is disposed on a die 51, and the vertical wall section 12 and the flange section
13 are pressed by the bending die 53 while pressing the top sheet section 11 with the pad
52 or causing the top sheet section 11 to come close to the pad 52. In FIG. 8, (a) shows
the behavior of the steel sheet S along the arrow a-a of FIG. 6 during pressing, and FIG. 8B
shows the behavior of the steel sheet S along the arrow b-b of FIG. 6 during pressing.
[0019]
An L-shaped component 10 has the planar top sheet section 11 having an L shape,
the vertical wall section 12, and the flange section 13 as shown in FIG. 6. The top sheet
section 11 is connected to the vertical wall section 12 with the bent section 15 including
the part 15a curved in the arc. The arc of the part 15a curved in the are shape has a shape
having a predetermined curvature, an elliptical shape, a shape having a plurality of
curvatures, a shape having a straight portion, or the like as viewed in the press direction.
That is, in the L-shaped component 10, the top sheet section 11 exists on the outside of the
are of the part 15a curved in the are shape, and the flange section 13 exists on the inside of
the arc (on the center point side of the arc) of the part 15a curved in the are shape. In
addition, the top sheet section 11 does not need to be completely planar, and may have
various additional shapes on the basis of the design of a press product.
[0020]
According to the invention, as shown in FIG. 6, from both end portions of the part
15a curved in the are shape in the L-shaped component 10, the end portion at a position
distant froth the end portion (the end portion of the lower side of the L shape) of the bent
section 15 is referred to as an end portion A (first end portion), and the end portion at a
position close to the end portion (the end portion of the lower side of the L shape) of the
bent section 15 is referred to as an end portion B ( second end portion). The bent section
15 has a part 15b extending substantially in a straight shape from the outside of the end
portion A (the opposite side to the end portion B), and a part 15c extending substantially in
a straight shape from the outside of the end portion B (the opposite side of the end portion
A). Here, there maybe a case where the end portion B of the part 15a curved in the are
15
shape is the same as an end portion of the bent section 15. In this case, the part 15c
extending substantially in the straight shape from the outside of the end portion B (the
opposite side of the end portion A) does not exist.
[0021]
The steel sheet S has a shape from which the L-shaped component 10 is
developed. That is, the steel sheet S has parts corresponding to the top sheet section 11,
the vertical wall section 12, the flange section 13, and the like in the L-shaped component
10.
As the steel sheet S (the blank metal sheet), a pre-processed steel sheet (blank
metal sheet) which is subjected to pre-processing such as press-forming, bend-forming, or
perforating may also be used.
[0022]
During forming of the vertical wall section 12 and the flange section 13, it is
preferable that, in the end portion A (first end portion) which is one end portion of the part
15a curved in the are shape of the bent section 15 when viewed in a direction
perpendicular to a surface of the top sheet section 11 (press direction), among portions of
an area of the top sheet section 11 divided by a tangent line of a boundary line between the
bent section 15 and the top sheet section 11, an area (a hatched portion of FIG. 10) which
contacts with the top sheet surface of the die 51 (a surface corresponding to the top sheet
section of the steel sheet S) in an area of a side including the end portion B (second end
portion) which is the other end portion of the part 15a curved in the are shape of the bent
section 15 be pressurized as an out-of-plane deformation suppressing area (area F). In
this case, generation of wrinkles of the top sheet section 11 or the vertical wall section 12
can be suppressed. During pad pressurization, it is preferable that a pad having a shape
that can cover the entire surface of the part of the steel sheet S that contacts with the top
sheet surface of the die 51 to a part of the steel sheet S that contacts with the top sheet
surface of the die 51 while including the entire out-of=plane deformation suppressing area
(the area F) be used. However, for example, when an additional shape exists in the
out-of-plane . deformation suppressing area (the area F) due to the design of a product, in
16
order to avoid the additional shape, a pad having a shape that can cover an area of at least
from a part of the out-of-plane deformation suppressing area (the area F) which contacts
with a boundary line with the part of the bent section curved in the arc shape, an area
within 5 mm from the boundary line, and to cover an area of 50% or larger of the
out-of-plane deformation suppressing area (the area F) may be used. Moreover, a pad in
which pressurizing surfaces are separated may be used.
[0023]
In addition, it is preferable that, in the steel sheet S, in a part of the top sheet
section 11, which abuts on a boundary line between the top sheet section 11 and the part
15a curved in the arc shape of the bent section 15, an area within at least 5 mm from the
boundary line be pressurized by the pad 52. On the other hand, for example, when only
an area within 4 nun from the boundary line is pressurized by the pad 52, wrinkles are
more likely to be generated in the top sheet section 11. Here, the generation of wrinkles
does not have a significant effect on product strength compared to the generation of
cracks.
[0024]
In FIG. 7, the die unit 50 used in the press-forming method according to this
embodiment is shown. The die unit 50 includes the die 51, the pad 52, and the bending
die 53.
A driving mechanism of the pad 52 used to pressurize the steel sheet S so that
in-plane movement can be allowed in the part corresponding to the out-of-plane
deformation suppressing area (the area F) may be a spring or a hydraulic pressure, and a
cushion gas may be used as the pad 52.
In addition, with regard to part that approaches or comes in contact with the
out-of-plane deformation suppressing area (the area F), a driving mechanism of the pad 52
used to form the vertical wall section 12 and the flange section 13 in a state where a
clearance of the pad 52 and the die 51 is maintained to be equal to or larger than the
thickness of the steel sheet S and to be equal to or smaller than 1.1 times the thickness
thereof may be a motor cylinder, a hydraulic servo apparatus, or the like.
17
[0025]
In the press-forming method according to this embodiment, the steel sheet S
having a shape from which a formed body is developed, which is shown in FIG. 9A, is
installed on the die 51 as shown in FIG. 9B. In addition, in the state where the part
corresponding to the top sheet section 11 of the L-shaped component 10 is pressurized
against the die 51 by the pad 52, the bending die 53 is lowered in the press direction P,
such that the vertical wall section 12 and the flange section 13 are formed as shown in FIG.
9C.
[0026]
As described above, as the bending die 53 is lowered in the press direction, the
steel sheet S is deformed along the shapes of the vertical wall section 12 and the flange
section 13. Here, in the steel sheet S, the part corresponding to the vertical wall section
12 of the lower side portion of the L shape flows into the vertical wall section 12. That is,
since the position in the steel sheet S corresponding to the top sheet section 11 of the lower
side portion of the L shape is stretched, generation of wrinkles in the top sheet section 11,
in which wrinkles are more likely to be generated due to an inflow of an excessive metal
material during typical drawing, is suppressed. In addition,; since the position in the steel
sheet S corresponding to the flange section 13 of the lower side portion of the L shape is
not excessively stretched, generation of cracks in the flange section 13, in which cracks
are more likely to be generated due to a reduction in the thickness of the sheet during
typical drawing, is suppressed. As the generation of wrinkles and cracks is suppressed as
described above, a large trim area for blank: holding does not need to be provided in the
part of the steel sheet S corresponding to the lower side portion of the L shape of the
L-shaped component, unlike a typical forming method.
[0027]
The shape of the steel sheet S may be a shape in which an end portion of at least a
part thereof is on the same plane as the top sheet section 11 (a shape in which the end
portion is not wound during press-forming). That is, as shown in FIG 10, it is preferable
that the end portion of the part corresponding to the out-of-plane deformation suppressing
18
area (the area F) in the steel sheet S be on the same plane as the top sheet section 11.
[0028]
If the height H of the vertical wall section 12 to be formed is smaller than 0.2
times the length of the part 15a curved in the are shape of the bent section 15 or smaller
than 20 mm, wrinkles are more likely to be generated in the vertical wall section 12.
Therefore, it is preferable that the height H of the vertical wall section 12 be equal to or
larger than 0.2 times the length of the part 15a curved in the are shape of the bent section
15 or equal to or larger than 20 mm.
[0029]
In addition, since a reduction in the thickness of the sheet due to forming is
suppressed, in addition to a steel sheet having high ductility and relatively low strength
(for example, a steel sheet having a breaking strength of about 1,600 MPa), even a steel
sheet having low ductility and relatively high strength (for example, a steel sheet having a
breaking strength of about 400 MPa) can be properly press-formed. Therefore, as the
steel sheet S, a high-strength steel sheet having a breaking strength of equal to or higher
than 400 MPa and equal to or lower than 1,600 MPa may be used.
[0030]
Moreover, in the press-forming method according to this embodiment, the width
h; of the flange section 13 on the upper side from the center of the curve of the vertical
wall maybe equal to or larger than 25 mm and equal to or smaller than 100 mm. More
specifically, it is preferable that the press-forming be performed so that in the flange
section 13 in a portion of the vertical wall section 12 connected to the part 15a curved in
the are shape of the bent section 15, the widths hi of a flange portion 13a of the end
portion A side from a center line C in a longitudinal direction (peripheral direction) of the
flange section 13 of the portion connected to the opposite side to the top sheet section 11
and a flange portion 13b (that is, an area 0) in front of the flange portion of the end
portion A side by 50 mm are equal to or larger than 25 mm and equal to or smaller than
100 mm.
The width hi is defined as a shortest distance from an arbitrary position in the
19
flange end portions of the flange portions 13a and 13b, to a position on the boundary line
between the vertical wall section and the flange section.
When points of which the widths h; are smaller than 25 mm exist in the flange
portions 13a and 13b, a reduction in the thickness of the flange section is increased, and
therefore cracks are more likely to be generated. This is because a force to draw the front
end portion of the lower side portion of the L shape into the vertical wall section 12 during
forming is concentrated on the vicinity of the flange section.
When points of which the widths h; are larger than 100 mm exist in the flange
portions 13a and 13b, an amount of the flange section 13 compressed is increased, and
therefore wrinkles are more likely to be generated.
Therefore, by causing the width h; to be equal to and larger than 25 mm and equal
to and smaller than 100 mm, generation of wrinkles and cracks in the flange section 13
can be suppressed.
Accordingly, when a component having a shape in which the width h, of the
flange section on the inside of the L shape is smaller than 25 mm is manufactured, it is
preferable that after press-forming the L shape having the flange section of which the
width is equal to or larger than 25 mm, unnecessary portions be trimmed.
[0031]
Furthermore, a radius of curvature of a maximum curvature portion of the curve
of the vertical wall section 12, that is, a radius (RMAX) of curvature of a maximum
curvature portion of the boundary line between the part 15a curved in the arc shape of the
bent section 15 and the top sheet section 11, be equal to or larger than 5 mm and equal to
or smaller than 300 mm.
When the radius of curvature of the maximum curvature portion is smaller than 5
mm, the periphery of the maximum curvature portion is locally pulled outward, and
therefore cracks are more likely to be generated.
When the radius of curvature of the maximum curvature portion is larger than
300 mm, the length of the front end of the lower portion of the L shape is lengthened and
thus the distance drawn into the inside (the vertical wall section 12) of the L shape is
20
increased during press-forming, so that a sliding distance between the die unit 50 and the
steel sheet S is increased. Therefore, wear of the die unit is accelerated, resulting in a
reduction in the life-span of the die. It is more preferable that the radius of curvature of
the maximum curvature portion be smaller than 100 mm.
[0032]
In the above-described embodiment, the forming method of a member having a
single L shape is exemplified. However, the invention can also be applied to forming of
a component having a shape of two L characters (a T-shaped component and the like), or a
component having a shape of two or more L characters (a Y-shaped component and the
like). That is, when a shape having a plurality of L characters is to be press-formed,
forming may be performed by the forming method of the L shape described above to form
a shape of a single L character, a plurality of L characters, or any L character. In addition,
the top sheet section 11 may have an L shape, a T shape, or a Y shape. Moreover, the top
sheet section 11 may have a T shape or Y shape which is left-right asymmetric.
In addition, a vertical positional relationship between the die 51 and the bending
die 53 is not limited to that of the invention.
Moreover, the blank metal sheet according to the invention is not limited only to
the steel sheet S. For example, blank metal sheets suitable for press-forming, such as, an
aluminum sheet or a Cu-Al alloy sheet may also be used.
Examples
[0033]
In Examples 1 to 52, formed bodies each of which has a top sheet section, a
vertical wall section, and a flange section were formed using a die unit having a pad
mechanism. Perspective views ((a) in the figures) of the formed bodies formed in
Examples 1 to 52, and plan views of an area 0 (an area of (arc length)/2 mm+50 mm), an
area F (an out-of-plane deformation suppressing area), and a pressurized position which
was actually pressurized and is shown as hatched sections ((b), (c), and (d) in the figures)
are shown in FIGS. 11 to 32. The unit of dimensions indicated in FIGS. 11 to 32 is mm.
21
In addition, the end portion A (the first end portion) and the end portion B (the second end
portion) of the formed body which is press-formed in each example are shown as A and B
in the figures, respectively.
[0034]
In Tables IA and 1B, figures corresponding to the respective examples are
indicated, and with regard to the material of the blank metal sheet used in each example,
"blank metal sheet type", "sheet thickness (mm)", and "breaking strength (MPa)" are
shown.
[0035]
In Tables 2A and 2B, with regard to the shape of the formed body formed in each
example, "top sheet shape", "arc length (mm)", "arc lengthx0.2", "radius of curvature of
maximum curvature portion of arc", "height H of vertical wall section", "A end flange
width (mm)", "shape of arc", "winding of end portion", "shape of front of A end", and
"additional shape of top sheet section" are shown.
[0036]
In Tables 3A and 3B, with regard to the forming condition, "pressurized position",
"pressurized range from boundary line (mm)", "pre-processing", "forming load (ton)",
"pad load pressure (MPa)", and "ratio of clearance between pad and die to sheet thickness
(clearance between pad and die/sheet thickness)" are shown.
[0037]
In Tables 4A and 4B, results of "wrinkle evaluation of flange section", "crack
evaluation of flange section", "wrinkle evaluation of top sheet section", "crack evaluation
of top sheet section", and "wrinkle evaluation of vertical wall section" are shown.
In the winkle evaluations of the flange section, the top sheet section, and the
vertical wall section, a case where no winkle was observed by visual inspection was
evaluated as A, a case where small winkles were observed was evaluated as B, a case
where winkles were observed was evaluated as C, a case where significant winkles were
observed was evaluated as D, and a case where buckling deformation was observed was
evaluated as X. In addition, in the crack evaluations of the flange section and the top
22
sheet section, a case where no crack was generated was evaluated as 0, a case where
necking (a portion where the sheet thickness is locally reduced by 30% or higher) was
generated was evaluated as A, and a case where cracks were generated was evaluated as X.
[0038]
[Table 1 A]
[0039]
[Table 1B]
[0040]
[Table 2A]
[0041]
[Table 2B]
[0042]
[Table 3A]
[0043]
[Table 3B]
[0044]
[Table 4A]
[0045]
[Table 4B]
[0046]
In Examples I and 41, a formed body shown in FIG. 11 was press-formed by
employing an appropriate forming condition. No crack and wrinkle was generated in the
formed body.
[0047]
In Examples 2 and 42, the formed body shown in FIG. 11 was press-formed by
setting the pad load pressure to be lower than that of Example 1. In the formed body,
wrinkles were generated in the top sheet section and small wrinkles were generated in the
vertical wall section. However, since no crack was generated, there was no problem with
product strength.
23
[0048]
In Examples 3, 43, and 44, the formed bodies shown in FIG 11 were
press-formed by setting the pad load pressure to be higher than that of Example 1.
Accordingly, the blank metal sheet could not sufficiently slide (perform in-plane
movement) in the pressurized position, and cracks were generated in the flange section.
[0049]
In Examples 45 to 52, the formed bodies shown in FIG. 11 were press-formed by
setting the ratio of the clearance between the pad and the die to the sheet thickness (the
clearance between the pad and the die/the sheet thickness) to 1.00 to 2.00. As a result, in
Example 49 in which the ratio of the clearance between the pad and the die to the sheet
thickness is set to 1.80 and in Example 52 in which the ratio of the clearance between the
pad and the die to the sheet thickness is set to 2.00, buckling deformation had occurred in
the top sheet section, so that a desired product shape could not be obtained.
[0050]
In Example 4, a formed body shown in FIG. 12 was press-formed by pressurizing
an area other than the out-of-plane deformation suppressing area (the area F) with the pad.
In the formed body, significant wrinkles were generated in the top sheet section, and small
wrinkles were generated in the vertical wall section. However, since no crack was
generated, there was no problem with product strength.
[0051]
In Example 5, a formed body shown in FIG. 13 was press-formed by pressurizing
an area including the entire out-of-plane suppressing area (the area F) with the pad. In
the formed body, no winkle and crack was generated.
[0052]
In Example 6, a formed body shown in FIG 14 was press-formed. In this
example, as shown in FIG. 14, since the end portion of the part corresponding to the
out-of-plane formation suppressing (the area F) does not exist on the same plane as the top
sheet section, that is, since the end portion is wound, cracks were generated in the flange
section.
24
[0053]
In Examples 7 to 10, formed bodies shown in FIGS. 15, 16, 17, and 18 were
press-formed. In these examples, even when the arc is elliptical (Example 7), the arc,has
a plurality of curvatures (R) (Example 8), the are has a straight portion (Example 9), or the
front end of the arc is the end portion of the bent section (Example 10), it could be seen
that the effects of the invention were sufficiently obtained.
[0054]
In Examples 11 to 13, formed bodies shown in FIGS. 19, 20, and 21 were
press-formed. In these examples, according to the product designs, even when the shape
of the front of the A end is non-straight (Examples 11 and 13), or the top sheet section has
an additional shape (Example 13), it could be seen that the effects of the invention were
sufficiently obtained. Particularly, in Example 13, even when the entire out-of-plane
deformation suppressing area (the area F) could not be pressurized by the pad since a
small additional shape existed in a part of the out-of-plane deformation suppressing area
(the area F), it could be seen that the effects of the invention were obtained.
[0055]
In Examples 14 to 17, formed bodies shown in FIG. 22 were press-formed by
setting the height H of the vertical wall section to 10 mm (Example 14), 15 mm (Example
15), 20 mm (Example 16), and 30 mm (Example 17). In these examples, it could be seen
that wrinkles of the vertical wall section could be suppressed by setting the height H of the
vertical wall section to 20 mm or larger. In Examples 14 and 15 in which the heights of
the vertical wall sections were smaller than 20 mm, winkles were generated in the vertical
wall sections. However, since no crack was generated, there was no problem with
product strength.
[0056]
In Examples 18 to 20, formed bodies shown in FIG. 23 were press-formed by
setting the height H of the vertical wall section to 5 mm (Example 18), 14 mm (Example
19), and 18 mm (Example 20) after setting the are length to 66 mm (arc lengthx0.2=13.2).
In this example, it could be seen that by setting the height H of the vertical wall section to
25
be equal to or larger than 0.2 times the arc length, wrinkles of the vertical wall section
could be suppressed even though the height of the vertical wall section was smaller than
20 mm. In Example 018 in which the height Hof the vertical wall section is smaller than
0.2 times the are length, wrinkles were generated in the vertical wall section. However,
since no crack was generated, there was no problem with product strength.
[0057]
In Example 21 to 23, formed bodies shown in FIGS. 24, 25, and 26 were
press-formed by pressurizing, in a part which contacts with a boundary line between the
top sheet section and the part curved in the are shape of the bent section, an area within 3
rnm (Example 21), 5 mm (Example 22), or 8 mm (Example 23) from the boundary line,
with the pad. In these examples, it could be seen that by pressurizing the area within at
least 5 mm from the boundary line with the pad, generation of wrinkles in the top sheet
section could be suppressed.
[0058]
In Examples 24 to 28, formed bodies shown in FIG. 27 were press-formed by
setting the flange width at the A end to 20 mm (Example 24), 25 mm (Example 25), 80
mm (Example 26), 100 mm (Example 27), and 120 mm (Example 28). In these
examples, it could be seen that by setting the flange width to be in the range of 25 mm to
100 mm, generation of wrinkles and cracks could be suppressed. In Example 24,
necking had occurred in the flange section by setting the flange width to 20 nun, and in
Example 28, significant wrinkles were generated in the flange section and necking had
occurred in the top sheet section by setting the flange width to 120 mm. However, since
no crack was exhibited, there was no significant problem with strength characteristics.
[0059]
In Examples 29 to 32, formed bodies shown in FIG. 28 were press-formed by
setting the radius of curvature of the maximum curvature portion of the arc to 3 mm
(Example 29), 5 mm (Example 30), 10 mm (Example 31), and 20 mm (Example 31) when
the arc has a straight portion (R+Straight+R). In these examples, it could be seen that by
setting the radius of curvature of the maximum curvature portion of the are to be equal to
26
or larger than 5 mm, wrinkles of the vertical wall section could be suppressed.
[0060]
In Examples 33 to 36, formed bodies were press-formed by setting the maximum
radius of curvature of the are to 200 mm (Example 33), 250 mm (Example 34), 300 mm
(Example 35), and 350 mm (Example 36). In these examples, it could be seen that by
setting the radius of curvature of the maximum curvature portion of the arc to be 300 mm
or smaller, generation of wrinkles of the vertical wall section could be suppressed.
[0061]
In Examples 37 and 38, a T-shaped formed body shown in FIG. 30 was
press-formed. As the blank metal sheet, a steel sheet (Example 37) obtained by
pre-processing the shape shown in FIG. 33 and a pre-processed aluminum sheet (Example
38) were used. In these examples, it could be seen that the press-forming method
according to the invention could be employed for forming the T-shaped formed body, and
the blank metal sheet according to the invention was not limited to the steel sheet.
[0062]
In Examples 39 and 40, a T-shaped formed body shown in FIG. 31, which is
left-right asymmetric (Example 39), and a Y-shaped formed body shown in FIG. 32
(Example 40) were press-formed. In these examples, it could be seen that the
press-forming method according to the invention could be adequately applied to forming
of a formed body having a shape of one or more L characters.
[Industrial' applicability]
[0063]
According to the invention, even when the blank metal sheet having low ductility
and high strength is used, the component having the L shape can be press-formed while
suppressing generation of wrinkles and cracks.
[Reference Signs List]
[0064]
27
10 L-shaped component
11 top sheet section
12 vertical wall section
13 flange section
15 bent section
15a part curved in an are shape
50 die unit
51 die
52 pad
53 bending die
100 framework structure
110 framework member
110' framework member
111 top sheet section
112 vertical wall section
113 flange section
120 framework member
130 framework member
140 framework member
201 die
202 punch
203 blank holder
300 component
300A blank metal sheet
300B formed body
S steel sheet (blank metal sheet)
h; flange width
1-1 height of vertical wall section
28
What is claimed is:
1. A forming method that forms a press component with an L shape from a blank metal
sheet, the press component having a top sheet section and a vertical wall section which is
connected to the top sheet section via a bent section having a part curved in an are shape
and which has a flange section on an opposite side to the bent section, the top sheet
section being arranged on an outside of the arc of the vertical wall section, the method
comprising:
disposing the blank metal sheet between a die amd both of a pad and a bending
die; and
forming the vertical wall section and the flange section while at least a part of the
blank metal sheet is caused to slide on a part of the die corresponding to the top sheet
section, the forming of the vertical wall section and the flange section being performed in
a state where the pad is made close to or brought into contact with the blank metal sheet.
2. The forming method according to claim 1, wherein, in the forming of the vertical wall
section and the flange section, a part of the metal sheet is pressurized as an out-of-plane
deformation suppressing area by the pad.
3. The forming method according to claim 1, wherein, in the forming of the vertical wall
section and the flange section, a portion of the metal sheet that is made close to or brought
into contact with an out-of-plane suppressing area of the pad as the out-of-plane
deformation suppressing area is formed in a state where a clearance between the pad and
the die is equal to or larger than a thickness of the blank metal sheet and is maintained to
be equal to or smaller than 1.1 times the thickness of the blank metal sheet.
4. The forming method according to claim 2 or 3, wherein the out-of-plane deformation
suppressing area is, among areas of the top sheet section divided by a tangent line of a
boundary line between the bent section and the top sheet section, the tangent line being
29
defined at a first end portion which is one end portion of the part curved in the are shape
of the bent section when viewed in a direction perpendicular to a surface of the top sheet
section, an area of the blank metal sheet which contacts with the part of the die
corresponding to the top sheet section on a side including a second end portion which is
other end portion of the part curved in the arc shape of the bent section.
5. The forming method according to any one of claims 2 to 4, wherein, in the end
portion of the blank metal sheet, among portions of the part of the blank metal sheet
corresponding to the out-of-plane deformation suppressing area, a portion which becomes
the end portion of the part further on the top sheet side than the bent section is on the same
plane as that of the top sheet section.
6. The forming method according to any one of claims I to 5, wherein the top sheet
section has an L shape, a T shape, or a Y shape.
7. The forming method according to any one of claims l to 6, wherein a height of the
vertical wall section is equal to or larger than 0.2 times a length of the part curved in the
are shape of the bent section, or equal to or larger than 20 nun.
8. The forming method according to any one of claims 1 to 7, wherein:
the forming of the vertical wall section and the flange section is performed so that
the pad is made close to or brought into contact with a region of the blank metal sheet; and
the region of the blank metal sheet is, among portions of the top sheet section, a
portion which is in contact with a boundary line between the top sheet section and the part
curved in the are shape of the bent section, and which is within at least 5 mm from the
boundary line.
9. The forming method according to any one of claims 4 to 8, wherein, in the flange
section, in a portion of the vertical wall section connected to the part curved in the are
30
shape of the bent section, widths of a flange portion of the first end portion side from a
center portion in a longitudinal direction of the flange of the portion connected to the
opposite side to the top sheet section and a flange portion in front of the flange portion of
the first end portion side by 50 mm or larger are equal to or larger than 25 mm and equal
to or smaller than 100 mm.
10. The forming method according to any one of claims 1 to 9, wherein a radius of
curvature of a maximum curvature portion of the boundary line between the part curved in
the are shape of the bent section and the top sheet section is equal to or larger than 5 mm
and equal to or smaller than 300 mm.
11. The forming method according to any one of claims 1 to 10, wherein a pre-processed
blank metal sheet is press-formed as the blank metal sheet.
12. The forming method according toany one of claims 1 to 11, wherein a blank metal
sheet having a breaking strength of equal to or higher than 400 MPa and equal to or lower
than 1,600 MPa is used as the blank metal sheet.
13. A forming method of a press component having an L shape, comprising:
performing forming by the forming method according to any one of claims 1 to
12 to form a shape of a single L character, a shape of a plurality of L characters, or a shape
of any L character, when a shape having a plurality of L characters is press-formed.
14. A forming method of a press component having an L shape, for forming an L shape
which has a vertical wall section, a flange section connected to one end portion of the
vertical wall section, and a top sheet section that is connected to an end portion of the
vertical wall section on the opposite side to a side connected to the flange section and
extends in the opposite direction to the flange section and in which a part or the entirety of
the vertical wall section is curved so that the flange section is on the inside, by pressing a
31
blank metal sheet, comprising:
performing forming by disposing a blank metal sheet having a shape in which an
end portion of a part of the blank metal sheet corresponding to a lower side of the L shape
is inside the top sheet section, on a die, and pressing the vertical wall section and the
flange section with a bending die while pressing the top sheet section with a pad.
15. The forming method according to claim 14, wherein a width of the flange section on
the upper side from the center of the curve of the vertical wall section is equal to or larger
than 25 mm and equal to or smaller than 100 mm.
16. A forming method of a press component having an L shape, for forming an L shape
which has a vertical wall section, a flange section connected to one end portion of the
vertical wall section, and a top sheet section that is connected to an end portion of the
vertical wall section on the opposite side to a side connected to the flange section and
extends in the opposite direction to the flange section and in which a part or the entirety of
the vertical wall section is curved so that the flange section is on the inside, by pressing a
blank metal sheet, comprising:
disposing the blank metal sheet having a shape in which an end portion of a part
of the blank metal sheet corresponding to the lower side of the L shape is inside the top
sheet section, a margin thickness is provided in the flange section on the upper side from
the center of the curve of the vertical wall section, and the sum of the thickness of the
flange section and the margin thickness is equal to or larger than 25 mm and equal to or
smaller than 100 mm, on a die;
performing forming by pressing the vertical wall section and the flange section
with a bending die while pressing the top sheet section with a pad; and
trimming the margin thickness of the flange section.
17. The forming method according to claim 16, wherein a radius of curvature of a
maximum curvature portion of the curve of the vertical wall section is equal to or larger
32
than 5 mm and equal to or smaller than 300 nun.
18. The forming method according to claim V6 or 17, wherein a pre-processed blank
metal sheet is press-formed as the blank metal sheet.
19. The forming method according to any one of claims 16 to 18, wherein a steel sheet
having a breaking strength of equal to or higher than 400 MPa and equal to or lower than
1,600 MPa is used as the blank metal sheet.
20. A forming method of a press component having an L shape, comprising:
performing forming by the forming method according to any one of claims 16 to
19 toform a shape of a single L character, a shape of a plurality of L characters, or a shape
of any L character, when a shape having a plurality of L characters is press-formed.