DESCRIPTION
PRESS COMPONENT AND METHOD AND DEVICE FOR MANUFACTURING SAME
Technical Field
[000 I] The present invention relates to a press component that has a hat shaped
cross-section and that is curved in an L shape along the longitudinal direction in plan view,
and a manufacturing method and manufacturing device for the same.
Background Art
[0002] Frame structures of vehicle bodies of automobiles are configured from plural frame
members obtained by press molding sheet metal (sheet steel is taken as an example of metal
stock sheet in the explanation that follows). Such frame components are very important
components for securing crash safety in automobiles. Known examples of frame members
include side sills, cross members, and front pillars.
[0003] Such frame members have hat shaped cross-sections configured from a top plate
section, two vertical walls joined to the both sides of the top plate section, and two flange
portions joined to the two respective vertical walls. Most of such frame members have a hat
shaped cross-section over a portion or the entirety thereof. High stren~o>th is desired in such
frame members in order to improve crash safety performance and to achieve weight reduction
in vehicles.
[0004] Fig. 19 is a perspective view of an example of a frame member 0 that has a hat
shaped cross-section and that has a straight shape along the longitudinal direction in plan view
and side view. Fig. 20 is a explanatory diagram of a front pillar 0-1 that is an example of a
frame member having a hat shaped cross-section. Fig. 20A is a perspective view and Fig.
20B is a plan view. Fig. 21 is a perspective view illustrating a component 1 having a hat
shaped cross-section and having a shape curved in an L shape along the longitudinal direction
in plan view. In the present specification, "plan view" refers to viewing the front pillar 0-1
from a direction orthogonal to the top plate section that is the widest planar portion on the
member (the direction of the white arrow in Fig. 20A, and the direction orthogonal to the page
in Fig. 20B).
[0005] The frame member 0 is a side sill or the like out of frame members having a hat
shaped cross-section, and has a shape that is substantially straight in the longitudinal direction
as ilhistrated in the example of Fig. 19. In contrast thereto, the front pillar 0-1 has a shape
like that illustrated in Fig. 20A and Fig. 20B. Namely, the front pillar 0-1 has a hat shaped
cross-section and includes a shape curved in an L shape along the longitudinal direction in
1
plan view as illustrated in Fig. 21, at the side of a! ower portion 0-2 ofthe front pillar 0-1.
[0006] Out of such components, the frame member 0 is manufactured mainly by bending
due to having a substantially straight shape along the longitudinal direction. Due to the
peripheral length of the cross-section of the frame member 0 not changing much along the
length direction, cracks and creases are not readily generated during press processing even
when formed from high strength sheet steel having low extensibility, and molding is simple.
[0007] For example, Patent Document I describes a method that forms a press component
having a hat shaped cross-section by bending. The method described in Patent Document I
manufactures press components that have a hat shaped cross-section and that have a
substantially straight shape along the longitudinal direction.
[0008] Fig. 22 is a perspective view illustrating a press component 1 manufactured by
bending that has a hat shaped cross-section and that has a shape curved in an L shape along
the longitudinal direction.
[0009] When the component 1 illustrated in Fig. 21 that has a hat shaped cross-section and
that is curved in an L shape along the longitudinal direction by bending using the method
described by Patent Document I, creases are generated in the flange portion (portion A) at the
outside of a curved portion 1a as illustrated in Fig. 22. Therefore, the component 1 is
generally molded by drawing in press processing. In drawing, steel stock sheet is molded
using a die, a punch, and a blank holder in order to control the amount of inflow of metal
stock sheet and to suppress generation of creases.
[0010] Fig. 23 is an explanatory diagram illustrating a component 2 to be molded that is
curved in an L shape along the longitudinal direction. Fig. 23A is a perspective view, and
Fig. 23B is a plan view. Fig: 24 is a plan view illustrating the shape of a steel stock sheet 3
when drawing, and a crease inhibiting region B in a steel stock sheet 3. Fig. 25A to Fig.
25D are cross-sections illustrating a mold structure and a molding procedure for drawing.
Fig. 26 is a perspective view of a drawn panel 5 that has been molded by drawing.
[0011] For example, molding employs a die 41, a punch 42, and a blank holder 43 as
illustrated in Fig. 25A to Fig. 25D, in order to mold a component 2 that is curved in an L
shape along the longitudinal direction in side view, illustrated in Fig. 23, by drawing.
I
[0012] First, as illustrated in Fig. 25A, the steel stock sheet 3 illustrated in Fig. 24 is
positioned between the punch 42 and the blank holder 43, and the die 41. Next, for example,
as illustrated in Fig. 25B, the crease inhibiting region B of the periphery of the steel stock
sheet 3 (the hatching shaded portion of Fig. 24) is held strongly by the blank holder 43 and
the die 41. Next, as illustrated in Fig. 25C, the die 41 is moved relatively in the direction of
the punch 42. Then finally, as illustrated in Fig. 25D, the drawn panel 5 illustrated in Fig.
2
26 is molded by processing the steel stock sheet 3 by pressing the steel stock sheet 3 against
the punch 42 using the die 41.
[0013] When doing so, the crease inhibiting region Bat the periphery of the steel stock sheet
3 is held strongly by the blank holder 43 and the die 41. Therefore, in the steel stock sheet3
obtained by the molded procedure, the steel stock sheet 3 is stretched in a region at the inside
of the crease inhibiting region in a state under tensile load. It is therefore possible to mold
while suppressing generation of creases. The unwanted portions at the periphery of the
molded drawn panel 5 are then cut away so as to manufacture the component 2 illustrated in
Fig. 23A and Fig. 23B.
Related Documents
Related Patent D.ocuments
[0014] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2006-015404
SUMMARY OF INVENTION
Technical Problem
[0015] Conventionally, shapes like that of the press component 1 are manufactured by press
molding using drawing as described above, by molding a steel stock sheet into the drawn
panelS illustrated in Fig. 26 and eliminating unwanted portions at the periphery of the drawn
panel 5 by trimming.
[0016] In this drawing method, a complicated shape can be molded, like that of the
component 2 that is curved in an L shape along the longitudinal direction in plan view.
However, as illustrated in Fig. 24, a large region for inhibiting creases is required around the
periphery of the steel stock sheet 3. Therefore after the steel stock sheet 3 has been molded
into the drawn panel, the unwanted portions eliminated by trimming are large portions,
decreasing material yield and increasing manufacturing cost.
[0017] Moreover, vertical walls 22, 24 illustrated in Fig. 23A are molded simultaneously in
the procedure that molds the drawn panel 5. Thus in the molding procedure, material
inflows from both sides of the top plate section 21 to mold the vertical walls 22,24 as
illustrated in Fig. 25B to Fig. 25D, without the steel stock sheet 3 moving significantly at the
portion that forms a top plate section 21. In particular, the flange portion (a pmtion D in Fig.
I
26) at the inside of a curved portion 5a that is curved in an L shape in plan view of the drawn
panel 5 assumes a molded state referred to as stretch flanging, and cracks develop in high
strength sheet steel having low extensibility. Is particular, extensibility is low in high
strength steel having a tensile stren1,rth of 590 MPa or above, making is difficult to process
without generating cracks in the portion D.
[0018] The comer where the vertical wall22 at the outside of a curved portion 2a meets the
3
of sheet thickness)/minimum value of sheet thickness) x 100, is 15% or less.
(12) The press component of (II) wherein the press component is an A pillar inner
panel that is a structural member of an automobile.
Advantageous Effects oflnvention
[0031] The present invention enables manufacture of a press component that has a hat
shaped cross-section and an L shaped curved portion that is curved along the longitudinal
direction in plan view, and that has excellent yield without causing creases or cracks to be
generated, by performing press molding on metal stock sheet formed from metal stock sheet
having tensile strength of from 200 MPa to 1600 MPa, and in particular, metal stock sheet
high strength material having a tensile strength of 590 MPa or greater.
BRIEF DESCRIPTION OF DRAWINGS
[0032] Figs. 1 A to IE are cross-sections illustrating a mold configuration and molding
process according to the present invention.
Figs. 2A to 2E are cross-sections illustrating another mold configuration and molding
process according to the present invention.
Fig. 3A is a plan view illustrating the shape of a metal stock sheet before molding;
and Fig. 3B is a plan view illustrating the shape of the metal stock sheet after a molding
procedure.
Fig. 4 is a plan view illustrating flow of material in the present invention.
Figs. SA to 5D are explanatory diagrams illustrating an example of a mold employed
in the present invention.
Fig. 6A to 6D are explanatory diagrams illustrating another example of a mold
employed in the present invention.
Figs. 7 A to 7D are explanatory diagrams illustrating another example of a mold
employed in the present invention.
Fig. 8 is an exploded perspective view of the mold illustrated in Figs. 7.
Figs. 9A to 9C illustrate a press component 1 molded in Comparative Examples I to
3 and in Examples I to 3, and are a front face view, a plan view, and a right side view,
I
respectively.
Fig. I 0 is a plan view illustrating the shape of a metal stock sheet employed in
Comparative Examples 1 to 3.
Fig. 11 is a plan view illustrating the shape of a metal stock sheet employed in
Examples I to 3.
Fig. 12 is a perspective view illustrating a configuration of the mold employed in
9
Examples 1 to 3.
Fig. 13A is a plan view illustrating the shape of metal stock sheet employed in
Example 4; and Fig. 13B is a perspective view of a press molded component.
Fig. 14A is a plan view illustrating the shape of a metal stock sheet employed in
Example 5; and Fig. 14B is a perspective view of a press molded component.
Fig. 15 is a plan view illustrating the shape of metal stock sheet employed in
Example 6.
Figs. 16A to 16C illustrate an intermediate shape molded in Example 6, and are a
front face view, a plan view, and a right side view, respectively.
Figs. 17 A to 17C illustrate the shape of a press component molded in Example 6, and
are a front face view, a plan view, and right side view, respectively.
Fig. 18 is a perspective view illustrating a mold configuration for performing
molding in Example 6 using the present invention.
Fig. 19 is a perspective view illustrating an example of a frame member that has a hat
shaped cross-section and that has a straight shape along the longitudinal direction in plan view
and in side view.
Fig. 20 is an explanatory diagram of a front pillar that is a frame member having a
hat shaped cross-section; Fig. 20A is a perspective view; and Fig. 20B is a plan view.
Fig. 21 is a perspective view illustrating a component that has a hat shaped
cross-section and that has a shape curved in an L shape along the longitudinal direction in
plan view.
Fig. 22 is a perspective view illustrating state of a press component that has a hat
shaped cross-section and that'has a shape curved in an L shape along the longitudinal
direction manufactured by bending.
Fig. 23 is an explanatory diagram illustrating a component to be formed that is
curved in an L shape along the longitudinal direction, Fig. 23A is a perspective view; and Fig.
23B is a plan view.
Fig. 24 is a plan view illustrating the shape of a metal stock sheet when drawing, and
a crease inhibiting region in the metal stock sheet.
I
Figs. 25A to 25D are cross-sections illustrating a mold for drawing and a procedure
for drawing.
Fig. 26 is a perspective view of a drawn panel formed by drawing.
Fig. 27 is a plan view explaining flow of material during drawing.
DESCRIPTION OF EMBODIMENTS
10
[0033] A press component according to the present invention, and a manufacturing method
for the same, are explained in sequence below.
I. Press Component I
As in the example described above of the shape in Fig. 21, the press component I has
a hat shaped cross-section and has the curved portion Ia that is curved in an L shape along the
longitudinal direction in plan view.
[0034] The press component 1 has a hat shaped cross-section configured from the top plate
section 11, the vertical walls 12, 14 joined to both sides of the top plate section 11, and flange
portions 13, 15 joined to the respective vertical walls 12, 14, and is shaped in an L shape in
plan view, due to curving along the longitudinal direction at the curved portion 1a (the
directions of the double-headed arrow in Fig. 21).
[0035] The press component 1 is generally employed in frame components for automobiles,
and is configured from metal stock sheet formed from high tension sheet steel having a sheet
thickness of from 0.8 mm to 3.2 mm and also having a tensile strength of from 590 MPa to
1800 MPa. The tensile strength of the metal stock sheet is preferably from 200 MPa to 1800
MPa in order to secure qualities such as the strength of the frame component for an
automobile, and the sheet thickness can be reduced when the tensile strength is 500 MPa or
above, and more so when the tensile strength is 590 MPa or above, with reduced sheet
thiclmess being preferable due to enabling component weight reduction. Moreover, 700
MPa or greater is most preferable.
[0036] In cases in which such high strength sheet steel is employed, resistance to inflow of
metal stock sheet during molding of the vertical wall 14 and the flange portion 15 at the inside
periphery of the curved portion 1 a becomes large when the width of the top plate section II is
too wide in plan view, and inflow of metal stock sheet toward the inside periphery of the
curved portion I a becomes insufficient. Therefore, the width of the top plate section 11 is
preferably 400 mm or less. However, when the width of the top plate section II is set too
narrow, sufficient pad pressure cannot be secured due to having to make the pressurizing
device for the pad, such as a gas cushion, small. The width of the top plate section 11 is
therefore preferably 30 mm or more.
I
[0037] Moreover, when the vertical walls 12, 14 are too high in side view, the resistance to
inflow of metal stock sheet during molding ofthe vertical wall 14 and the flange portion 15 at
the inside periphery of the curved portion I a becomes large, and the inflow of metal stock
sheet to the inside periphery of the curved portion I a becomes insufficient. Therefore, the
height of the vertical walls 12, 14 is preferably 300 mm or less.
[0038] When the curvature of the inside periphery of the curved portion Ia is too small in
II
plan view, the inflow of metal stock sheet to the inside periphery of the curved portion 1 a
during molding of the flange portion 15 at the inside periphery of the curved portion Ia
becomes insufficient. Therefore, the curvature of the vertical wall 14 at the inside periphery
of the curved portion Ia is preferably 5 mm or more in plan view.
[0039] Therefore, the width oftop plate section II is preferably from 30 mm to 400 mm in
plan view, the height of the vertical walls 12, 14 is preferably 300 mm or less in side view,
and the curvature of the inside periphery of the curved portion Ia is preferably 5 mm or more
in plan view.
[0040] Moreover, the proportional decrease in the sheet thickness of the press component I
as calculated by ((maximum value of sheet thickness- minimum value of sheet thiclmess)/
maximum value of sheet thickness) x I 00 is 15% or less. Hitherto there has been no press
component I with such a low proportional decrease in sheet thiclmess. Having such a low
proportional decrease in the sheet thickness of the press component I that is a structural
member of an automobile gives excellent crash safety performance, and enables a vehicle
weight reduction to be achieved since configuration is made from high tension sheet steel
with a tensile strength of from 590 MPa to 1800 MPa.
[0041] 2. Manufacturing Method and Manufacturing Device for Press Component
Fig. lA to Fig. IE are cross-sections illustrating a mold configuration and molding
process according to the present invention.
[0042] The mold illustrated in Fig. lA to Fig. IE is employed in the present invention to
mold the press component I by press molding metal stock sheet.
[0043] The mold includes a punch 72 and a blank holder 73, and a pad 74, a die 71, and a
bender 75 that are positioned facing the punch 72 and the blank holder 73.
[0044] The punch 72 has a shape that includes sheet thickness back face side shapes of the
top plate section II of the press component I, the vertical wall 14 positioned at the inside
periphery of the curved portion Ia, and the flange portion 15.
[0045] The blank holder 73 has a shape that includes the sheet thickness back face side
shape of the flange portion l3 joined to the vertical wall 12 positioned at the outside periphery
of the curved portion Ia.
[0046] The pad 74 is shaped so as to face toward the blank holder 73 'and has a shape that
includes the sheet thickness front face side shape ofthe top plate section II.
[0047] The die 71 has a shape that includes the respective sheet thickness front face side
shapes of the vertical wall 12 and the flange portion 13 that are positioned at the outside
periphery of the curved portion Ia.
[0048] The bender 75 has a shape that includes the respective sheet thickness front face side
12
shapes of both the vertical wall 14 and the flange portion 15 that are positioned at the outside
periphery of the curved portion 1a.
[0049] Fig. 2A to Fig. 2E are cross-sections illustrating another mold configuration and
another molding process according to the present invention.
[0050] The differences from the mold illustrated in Fig. I are that a locking mechanism 76,
described later, is installed to the punch 72, and that the bender 75 is installed to a sub-base
(not illustrated).
[0051] The locking mechanism 76 is configured from a pin disposed so as to be retractably
inserted into the punch 72. The locking mechanism 76 is completely housed in the punch 72
from molding start to the molding bottom dead center (Fig. 2A to Fig. 2D), and then at the
molding bottom dead center, the locking mechanism 76 is protruded to the blank holder 73
side, and fixes the blank holder 73 to the punch 72. When demolding, the locking
mechanism 76 prevents the molded press component 1 from being damaged by pad pressure
by achieving a state in which the blank holder 73 is fixed to the punch 72 while the bender 75,
the pad 74, and the sub-base are being raised in demolding.
[0052] A mechanism that fixes (retains) the positional relationship in demolding between the
pad 74, and the sub-base (the bender 75) and the die 75 (drawing die) may be employed as the
locking mechanism 76. For example, configuration may be such that (a) the pad74 is fixed
to the sub-base, and at the same time the bender 75 (drawing die) is fixed to the pad 74 or the
sub-base when demolding, (b) the separation between the blank holder 73 and the pad 74 is
fixed when demolding by inserting a spacer, or (c) the positional relationship between the pad
74 and the bender 75 is fixed (retained) when demolding. The sub-base is described later.
[0053] Metal stock sheet is molded into the press component I using such a mold.
Fig. 3A is a plan view illustrating a state prior to molding a metal stock sheet 8. Fig.
3B is a plan view illustrating the shape of the metal stock sheet 8 during a molding procedure.
Fig. 4 is a plan view illustrating flow of material in the present invention.
[0054] First, as illustrated in Fig. lA, the metal stock sheet 8 having the shape illustrated in
Fig. 3A is placed between the punch 72 and blank holder 73, and the pad 74, die 71, and
bender 75.
I
[0055] Next, as illustrated in Fig. lB, the portion of the metal stock sheet 8 for forming the
top plate section II is pressed against the punch 72 by the pad 74 under pressure, and, while
clamped in this manner, a portion of the metal stock sheet 8 further to the outside of the
curved portion I a than the portion for forming the top plate section 11 is pressed against the
die 71 by the blank holder 73 under pressure, and clamped.
[0056] Next, as illustrated in Fig. I C, the metal stock sheet 8 is molded into the shape
13
illustrated in Fig. 3B by relatively moving the bender 75 in the direction toward where the
punch 72 is placed, working the metal stock sheet 8, and molding the vertical wall 14 and the
flange portion 15 at the inside periphery of the curved portion Ia.
[0057] When doing so, a portion of the metal stock sheet 8 clamped between the punch 72
and the blank holder 73, and the pad 74 and the die 71, also inflows to the inside periphery of
the curved portion 1 a and is molded due to the metal stock sheet 8 only being pulled from the
inside of the curved portion 1 a.
[0058] Thus, unlike cases in which pulled during drawing is from both the outside and the
inside of the curved portion Ia (see Fig. 27), as illustrated in Fig. 4, at the flange portion (the
portion D) at the inside periphery of the curved portion Ia, the metal stock sheet 8 does not
move to a great extent in the molding procedure from the inside to the outside of the curvature
of the curved portion Ia, and the metal stock sheet 8 is bent overall by a longitudinal leading
end of the metal stock sheet 8 inflowing to the inside periphery of the curved portion 1 a.
The flange portion 15 that forms the inside of the bend (the portion D) at the inside of the
curved portion I a tends to be compressed. The amount of stretching of the flange portion 15
at the inside periphery of the curved portion 1 a (the pmtion D) during molding is therefore
greatly reduced compared to during drawing.
[0059] Then, as illustrated in Fig. 1D, after molding of the vertical walll4 and the flange
pmtion 15 at the inside of the curved portion 1a has finished, the metal stock sheet 8 is
pressed against the die 71 by the blank holder 73 under pressure, the die 71 and the blank
holder 73 are moved relatively with respect to the metal stock sheet 8 in the direction toward
where the blank holder 73 is positioned while maintaining the clamped state, the metal stock
sheet 8 is worked, and the vertical walls 12 and the flange portions 13 at the outside periphery
of the curved portion 1a are molded. The press component 1 illustrated in Fig. 3 is thereby
molded.
[0060] When doing so, in the procedure for molding the vertical wall 14 and the flange
portion 15 at the inside periphery of the curved portion I a, the portion for forming the top
plate section 11 and the flange portion 15 both inflow to the inside periphery of the curved
portion Ia, giving compression in the longitudinal direction and resulting in a state in which
I
there is residual compression stress. The corner where the vertical wall 12 and the top plate
section 11 meet at the outside periphery of the curved portion 1 a that is greatly stretched in
the molding procedure (a portion C in Fig. 4) is thus also molded into a shape by being pulled
out from the state in which there is residual compression stress. The extensibility required of
the material is therefore small compared to cases in which drawing is performed by molding
from a state without compression stress. Cracks are accordingly suppressed from
14
developing and favorable molding is enabled as a result, even when a high strength material
having low extensibility (for example, high tension steel of 590 MPa grade or above) is
employed as the metal stock sheet 8.
[0061] Bending is performed using the bender 75 during molding ofthe vertical wall 14 and
the flange portion 15 at the inside periphery of the curved portion Ia, and molding with metal
stock sheet 8 is accordingly possible and it is possible to achieve a high material yield, due to
not requiring the crease inhibiting region that was necessary during drawing for the portion at
the inside periphery of the curved portion Ia and for a longitudinal direction leading end
portion.
[0062] Finally, as illustrated in Fig. IE, after molding of the press component 1 has been
completed, in order to take the molded press component I out from the mold after molding,
the blank holder 73 is fixed so as not to move relatively with respect to the punch 72 by using,
for example, the locking mechanism 76, the blank holder 73 is rendered so as not to press the
molded press component I against the die 71, and the pad 74, and the die 71 and the bender
75 are moved relatively away from the blank holder 73 and the punch 72. The press
component I is thereby able to be taken out without being deformed or damaged by being
pressed by the pad 74 or the blank holder 73.
[0063] The manufacturing device for the press component has been outlined above, and
detailed explanation regarding the configuration of the mold follows.
[0064] Fig. SA to Fig. 5D are explanatory diagrams illustrating an example of a mold
employed by the present invention. The locking mechanism 76 is omitted from Fig. 5 to Fig.
7.
[0065] In the mold, the bender 75, the die (drawing die) 71, and the pad 74 are each directly
supported by a die base 77, and are each driven independently with respect to the die base 77.
The mold can be made more compact overall since a frame or the like is not employed to
support the bender 75 or the blank holder 73.
[0066] Fig. 6A to Fig. 6D are explanatory diagrams illustrating another example of a mold
employed in the present invention.
The mold has a structure in which sub-bases 75 embrace the pad 74 and the die
I
(drawing die) 71, and eccentric load from the pad 74 and the die (drawing die) 71 is borne by
the sub-base 75 that is integrated together with a bender. An improvement is thereby
achieved in mold shaping over the example mold illustrated in Fig. 5.
[0067] Fig. 7 A to Fig. 7D are explanatory diagrams illustrating another example of a mold
employed in the present invention. Fig. 8 is an exploded perspective view of the mold.
[0068] Such a mold enables the burden ofload of the pad 74 being exerted on the bender 75
15
to be avoided by incorporating the pad 74 into the die base 77 rather than the bender 75. An
improvement is thereby achieved in sub-base mold deformation over the example mold
illustrated in Fig. 6 since orthogonal direction load imparted to the sub-base is entirely
received from the bender.
[0069] The examples of molds illustrated in Fig. SA to Fig. 50, Fig. 6A to Fig. 60, and Fig.
7A to Fig. 7D are all molds haying structures that are particularly effective for implementing
the manufacturing method according to the present invention. However, since the structure
that suppresses mold deformation affects the mold cost and size, which stmcture of mold to be
employed may be appropriately decided in consideration of the size and shape of the
component to be manufactured, and the rigidity required by the mold in view of the strength
ofthe steel stock sheet to be employed.
Examples
[0070] Fig. 9A to Fig. 9C illustrate the press component 1 to be molded in Comparative
Examples I to 3 and in Examples 1 to 3, and are a front face view, a plan view, and a right
side view, respectively .. Fig. 10 is a plan view illustrating the shape of the metal stock sheet
8 employed in Comparative Examples I to 3. Fig. II is a plan view illustrating the shape of
the metal stock sheet 8 employed in Examples I to 3. Fig. 12 is a perspective view
illustrating the configuration of the mold employed in Examples I to 3.
[0071] The results for Comparative Examples I to 3 and Examples 1 to 6 are listed'
collectively in Table 1.
In Comparative Examples I to 3 and in Examples I to 3, the press component 1
having the shape illustrated in Fig. 9A to Fig. 9C is manufactured using sheet steel of sheet
thickness 1.2 mm, and breaking strengths of270 MPa, 590 MPa, and 980 MPa as the metal
stock sheet, using as the manufacturing method both a conventional drawing method and the
present invention.
[0072] Note that the units of the numerical values in Fig. 9 to Fig. II are millimeters. Note
that the material yields in Table I are ratios of the material that goes to form the component to
metal stock sheet.
16
[0073] Table 1
Breaking strength Sheet thickness Manufacturing Molded Material
of metal stock of metal stock method state * yield
sheet sheet
Comparative 270MPa 1.2mm Drawing Good 63%
Example I
Comparative 590 MPa 1.2mm Drawing Bad N/A
Example 2
Comparative 980MPa 1.2mm Drawing Bad N/A
Example 3
Example 1 270MPa 1.2mm Present invention Good 99%
.
Example 2 590MPa 1.2mm Present invention Good 99%
Example 3 980MPa 1.2mm Present invention Good 99%
Example4 590MPa 1.2mm Present invention Good 99%
Example 5 590MPa 1.2mm Present invention Good 99%
Example 6 980MPa 1.2mm Present invention Good 92%
* Good: no cracks were generated; Bad: cracks were generated.
[0074] Comparative Example 1 and Example 1 are examples, in which pressing was
performed employing low strength sheet steel with excellent extensibility and a breaking
strength of270 MPa. Although molding succeeded without cracking in both cases, it was
confirmed that Example 1 was highly advantageous over Comparative Example 1 in terms of
material yield.
[0075] Comparative Examples 2 and 3, and Examples 2 and 3 are examples in which
pressing was performed employing high strength sheet steel with low extensibility as the
metal stock sheet. Although cracks developed and molding was not achieved in
Comparative Examples 2 and 3, favorable molding without cracking was achieved in
Examples 2 and 3.
[0076] Fig. 13A is a plan view illustrating the shape of the metal stock sheet 8 employed in
Example 4. Fig. 13B is a perspective view of the press component 1.
I
[0077] Example 4 is an example in which the press component I having the shape illustrated
in Fig. 13B was molded employing sheet steel of sheet thickness 1.2 mm having a breaking
strength of 590 MPa as the metal stock sheet, worked into the shape illustrated in Fig. 13A.
It was confirmed that favorable molding was possible even when such non-planar metal stock
sheet is employed.
17
[0078] Fig. 14A is a plan view illustrating the shape of the metal stock sheet 8 employed in
Example 5. Fig. 14B is a perspective view of the press component I.
[0079] Example 5 is an example in which molding was performed to the shape illustrated in
Fig. 14B by employing sheet steel having a sheet thickness of 1.2 mm, a breaking strength of
590 MPa, and a flat plate shape illustrated in Fig. 14A, as the metal stock sheet. Although
the top plate section was not flat, favorable molding was achieved by working the top plate
section by working using the pad.
[0080] Fig. 15 is a plan view illustrating the shape of the metal stock sheet employed in
Example 6. Fig. 16A to Fig. 16C illustrate an intermediate shape molded in Example 6, and
are a front face view, a plan view, and a right side view, respectively. Fig. 17 A to Fig. 17C
illustrate the shape of the press component I molded in Example 6, and are a front face view,
a plan view, and a right side view, respectively. Fig. 18 is a perspective view illustrating a
mold configuration for molding using the present invention in Example 6.
[0081] Example 6 is an example is in which the complicated shape illustrating in Fig. 17 A to
Fig. 17C was molded by employing high strength sheet steel having a sheet thickness of 1.2
mm, low extensibility, and tensile strength of 980 MPa, as the metal stock sheet. Metal
stock sheet having the shape illustrated in Fig. 15 was employed as the metal stock sheet, and
using a mold having the configuration illustrated in Fig. 18, the intermediate shape illustrated
in Fig. 16A to Fig. 16C was molded using the present invention, and the press component I
having the shape illustrated in Fig. 17 A to Fig. 17C was then favorably molded without
generating cracks or creases being generated by further post-working.
Explanation of the Reference Numerals
[0082]
press component
I a curved portion
8 metal stock sheet
II top plate section
12 vertical wall at outside periphery of curved portion
13 flange portion at outside periphery of curved portion
14 vertical wall at inside periphery of curved portion
15 flange portion at inside periphery of curved portion
2 component
21 top plate section
22 vertical wall at outside of L shaped curve
23 flange joined to vertical wall at outside of L shaped curve

CLAIMS
1. A manufacturing method for a press component in which press working is performed on a
metal stock sheet to mold a press component having an L shaped hat shaped cross-section
formed from a hat shaped cross-section configured by a top plate section, two vertical walls
joined to both sides of the top plate section, and two flanges joined to the two respective
vertical walls, and from a curved portion that curves along the longitudinal direction in plan
view, or a press component having such an L shaped hat shaped cross-section over a portion
thereof, the method comprising molding the press component by:
placing the metal stock sheet between a punch and a blank holder, and a pad, a die,
and a bender;
pressing and clamping a portion of the metal stock sheet for forming the top plate
section against the punch using the pad, and pressing and clamping a portion of the metal
stock sheet that will be further to the outside of the curve portion than the portion of the metal
stock sheet for forming the top plate section against the die using the blank holder; and
after molding the vertical wall at the inside periphery of the curved portion and the
flange portion joined to that vertical wall through working the metal stock sheet by relatively
moving the bender in the direction toward where the punch is positioned,
molding the vertical wall at the outside periphery of the curved portion and the flange
portion joined to that vertical wall, by relatively moving the die and the blank holder in the
direction toward where the blank holder is positioned relative to the metal stock sheet and
working the metal stock sheet while maintaining the state in which the metal stock sheet is
pressed and clamped against the die by the blank holder.
2. The manufacturing method for a press component of claim 1, wherein:
the punch has a shape including sheet thickness back face side shapes of each of the
top plate section, the vertical wall positioned at the inside periphery of the curved portion, and
the flange portion joined to that vertical wall;
the blank holder has a shape including the sheet thickness back face side shape of the
flange portion joined to the vertical wall positioned at the outside periphery of the curved
portion;
the pad is shaped so as to face toward the blank holder and has a shape including the
sheet thickness front face side shape of the top plate section;
the die has a shape including the sheet thickness front face side shapes of each of the
vertical wall positioned at the outside periphery of the curved portion, and the flange portion
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joined to that vertical wall; and
the bender has a shape including the sheet thickness front face side shape of each of
the vertical wall positioned at the inside periphery of the curved portion, and the flange
portion joined to that vertical wall.
3. The manufacturing method for a press component of claim 1 or claim 2, wherein
the metal stock sheet is a pre-worked metal sheet.
4. The manufacturing method for a press component of any one of claim 1 to claim 3,
wherein,
after molding the press component, the press component is taken out from the mold
by fixing the blank holder so as not to move relative to the punch, and moving the pad, the die,
and the bender relatively away from the blank holder and the punch, such that blank holder
does not press the molded press component against the die under pressure.
5. The manufacturing method for a press component of any one of claim 1 to claim 4,
wherein,
the metal stock sheet is high tensile sheet steel having a sheet thickness of from 0.8
mm to 3.2 mm, and a tensile strength of from 590 MPa to 1800 MPa.
6. The manufacturing method for a press component of any one of claim 1 to claim 5,
wherein:
more.
the width of the top plate section in plan view is from 30 mm to 400 mm;
the height of the vertical walls in side view is 300 mm or less; and
the curvature at the inside periphery of the curved portion in plan view is 5 mm or
7. A manufacturing device for a press component, the manufacturing device comprising a
punch and a blank holder, and a pad, a die and a bender that are disposed facing the punch and
the blank holder, wherein the manufacturing device performs press working on a metal stock
sheet to mold a press component having an L shaped hat shaped cross-section formed fi'om a
hat shaped cross-section configured by a top plate section, two vertical walls joined to both
sides of the top plate section, and two flanges joined to the two respective vertical walls, and
from a curved portion that curves along the longitudinal direction in plan view, or a press
component having such an L shaped hat shaped cross-section over a portion thereof, the
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manufacturing device molding the press component by:
performing first molding that molds the vertical wall at the inside periphery of the
curved portion and the flange portion joined to that vertical wall by the pad pressing and
clamping a portion of the metal stock sheet for forming the top plate section against the punch,
the blank holder pressing and clamping a portion of the metal stock sheet that will be further
to the outside of the curve portion than the portion of the metal stock sheet for forming the top
plate section against the die, and working the metal stock sheet by relatively moving the
bender in the direction toward where the punch is positioned; and
performing second molding to mold the vertical wall at the outside periphery of the
curved portion and the flange portion joined to that vertical wall by, after the first molding has
been performed, relatively moving the die and the blank holder in the direction toward where
the blank holder is positioned relative to the metal stock sheet and working the metal stock
sheet while maintaining the state in whieh the metal stock sheet is pressed and clamped
against the die by the blank holder.
8. The manufacturing device for a press component of claim 7, further comprising
a locking mechanism that fixes the blank holder such that the blank holder cannot
move relative to the punch during demolding after molding has been completed.
9. The manufacturing device for a press component of claim 7 or claim 8, further
comprising
a sub-base that supports the pad and the die so as to be capable of being raised and
lowered, and that is configured integrated together with the bender; and
a die base that supports the sub-base so as to be insertable and retractable.
10. The manufacturing device for a press component of claim 7 or claim 8, further
compnsmg:
a sub-base that supports the die so as to be capable of being raised and lowered, and
that is configured integrated together with the bender; and
a die base that supports the pad so as to be capable of being raised and lowered, and
that supports the sub-base so as to be inse1iable and retractable.
11. A press component having a hat shaped cross-section configured from a top plate section,
two vertical walls joined to both sides of the top plate, and two flange portions joined to the
two respective vertical walls, and having a shape curved in an L shape along the longitudinal
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direction in plan view due to including a curved portion, wherein:
the press component is a press molded. body configured by employing high tensile
sheet steel having a sheet thickness of from 0.8 mm to 3.2 mm and tensile strength of from
590 MPa to 1800 MPa as metal stock sheet;
the width of the top plate section in plan view is from 30 mm to 400 mm, the height
of the vertical walls in side view is 300 mm or less, and the curvature of the inside periphery
of the curved portion in plan view is 5 mm or more; and
the proportional decrease in the sheet thiclmess, as calculated by ((maximum value of
' sheet thickness- minimum value of sheet thickness)/minimum value of sheet thickness) x 100,
is 15% or less.
12. The press component of claim 11 wherein the press component is an A pillar inner panel
that is a structural member of ari automobile.