U.S. patent application number 14/353624 was filed with the patent office on 2014-10-09 for hot press molding method, article molded by hot press molding, and mold for hot pressing.
This patent application is currently assigned to AISIN TAKAOKA CO., LTD.. The applicant listed for this patent is Tetsuji Egawa, Masaki Furuhashi, Hideaki Ikezawa, Kenji Kato, Hidetoshi Kimura, Takanobu Suzuki. Invention is credited to Tetsuji Egawa, Masaki Furuhashi, Hideaki Ikezawa, Kenji Kato, Hidetoshi Kimura, Takanobu Suzuki.
Application Number | 20140302341 14/353624 |
Document ID | / |
Family ID | 48167341 |
Filed Date | 2014-10-09 |
United States Patent
Application |
20140302341 |
Kind Code |
A1 |
Egawa; Tetsuji ; et
al. |
October 9, 2014 |
HOT PRESS MOLDING METHOD, ARTICLE MOLDED BY HOT PRESS MOLDING, AND
MOLD FOR HOT PRESSING
Abstract
In a hot press molding method for press-molding a heated
material and cooling the material while holding the material in a
mold, during press molding of the material, shape changes including
a portion that curves with respect to a longitudinal direction of
the material are molded at longitudinal opposite end portions of
the material and resistance to thermal contraction force of the
material in the longitudinal direction during cooling is imparted.
In one embodiment of the present invention, the shape changes
molded on the material during the press molding are minute
protrusions provided on surfaces of the longitudinal opposite end
portions of the material. The invention makes it possible to
suppress thermal contraction of the material during cooling in hot
press molding to thereby prevent defects associated therewith.
Inventors: |
Egawa; Tetsuji;
(Okazaki-shi, JP) ; Suzuki; Takanobu;
(Miyoshi-shi, JP) ; Kimura; Hidetoshi;
(Toyota-shi, JP) ; Ikezawa; Hideaki; (Okazaki-shi,
JP) ; Kato; Kenji; (Nagoya-shi, JP) ;
Furuhashi; Masaki; (Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Egawa; Tetsuji
Suzuki; Takanobu
Kimura; Hidetoshi
Ikezawa; Hideaki
Kato; Kenji
Furuhashi; Masaki |
Okazaki-shi
Miyoshi-shi
Toyota-shi
Okazaki-shi
Nagoya-shi
Toyota-shi |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
AISIN TAKAOKA CO., LTD.
Toyota-shi, Aichi
JP
TOYOTA JIDOSHA KABUSHIKI KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
48167341 |
Appl. No.: |
14/353624 |
Filed: |
December 26, 2011 |
PCT Filed: |
December 26, 2011 |
PCT NO: |
PCT/JP2011/080102 |
371 Date: |
April 23, 2014 |
Current U.S.
Class: |
428/600 ;
72/342.5 |
Current CPC
Class: |
B21D 22/022 20130101;
B21D 53/88 20130101; B21J 5/02 20130101; B21D 37/16 20130101; B21D
22/208 20130101; Y10T 428/12389 20150115 |
Class at
Publication: |
428/600 ;
72/342.5 |
International
Class: |
B21J 5/02 20060101
B21J005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2011 |
JP |
2011-237498 |
Claims
1. A hot press molding method for press-molding a heated material
and cooling the material while holding the material in a mold,
wherein, during press molding of the material, shape changes
including a portion that curves with respect to a longitudinal
direction of the material are molded at longitudinal opposite end
portions of the material and resistance to thermal contraction
force of the material in the longitudinal direction during cooling
is imparted.
2. The hot press molding method according to claim 1, wherein the
shape changes molded on the material during the press molding are a
plurality of minute protrusions provided on surfaces of the
longitudinal opposite end portions of the material.
3. The hot press molding method according to claim 1, wherein the
shape changes molded on the material during the press molding are
flanges molded on the longitudinal opposite ends of the
material.
4. A hot press molded article obtained by the hot press molding
method according to claim 1.
5. A mold for hot pressing, the mold including an upper mold and a
lower mold, for sandwiching a heated material between the upper
mold and the lower mold to press-mold the material, and for holding
the material in the mold to cool the material, wherein a plurality
of protruding portions protruding toward the upper mold or a
plurality of recessed portions recessed from the upper mold toward
the lower mold are provided at a portion of the lower mold
corresponding to a longitudinal end portion of the material, a
plurality of recessed portions or a plurality of protruding
portions corresponding to the protruding portions or the recessed
portions provided to the lower mold are provided to the upper mold,
and a plurality of minute protrusions are molded on a surface of
the longitudinal end portion of the material by the protruding
portions or the recessed portions provided to the lower mold and
the recessed portions or the protruding portions provided to the
upper mold during press molding with the upper mold and the lower
mold.
6. A mold for hot pressing, the mold including an upper mold and a
lower mold, for sandwiching a heated material between the upper
mold and the lower mold to press-mold the material, and for holding
the material in the mold to cool the material, wherein a flange
bending from the upper mold toward the lower mold or from the lower
mold toward the upper mold is molded at a longitudinal end of the
material by the upper mold and the lower mold during the press
molding.
7. A hot press molded article obtained by the hot press molding
method according to claim 2.
8. A hot press molded article obtained by the hot press molding
method according to claim 3.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hot press molding
technique.
BACKGROUND ART
[0002] Conventionally, hot press molding for cooling material
heated to a quenching temperature while press-molding the material
in a mold to thereby quench the material is widely used (see Patent
Document 1, for example).
CITATION LIST
Patent Literature
[0003] Patent Document 1: JP 2008-284574 A
SUMMARY OF INVENTION
Technical Problem
[0004] Metal material such as steel to be hot press-molded expands
when heated and contracts when cooled. Because of the contraction
of the material in the mold, defects such as biting of a molded
article into the mold and dimensional errors of a shape of the
molded article may be caused.
[0005] Therefore, the technique for avoiding the defects caused by
the thermal contraction of the material when the material is cooled
in a hot press machine is required.
Technical Solutions
[0006] In accordance with an aspect of the present invention, there
is provided a hot press molding method for press-molding a heated
material and cooling the material while holding the material in a
mold, wherein, during press molding of the material, shape changes
including a portion that curves with respect to a longitudinal
direction of the material are molded at longitudinal opposite end
portions of the material and resistance to thermal contraction
force of the material in the longitudinal direction during cooling
is imparted.
[0007] In accordance with another aspect of the invention, in the
hot press molding method, the shape changes molded on the material
during the press molding are preferably a plurality of minute
protrusions provided on surfaces of the longitudinal opposite end
portions of the material.
[0008] In accordance with another aspect of the invention, in the
hot press molding method, the shape changes molded on the material
during the press molding are preferably flanges molded on the
longitudinal opposite ends of the material.
[0009] According to another aspect of the invention, there is
provided a hot press molded article obtained by any one of the
above-described hot press molding methods.
[0010] According to another aspect of the invention, there is
provided a mold for hot pressing, the mold including an upper mold
and a lower mold, for sandwiching a heated material between the
upper mold and the lower mold to press-mold the material, and for
holding the material in the mold to cool the material, wherein a
plurality of protruding portions protruding toward the upper mold
or a plurality of recessed portions recessed from the upper mold
toward the lower mold are provided at a portion of the lower mold
corresponding to a longitudinal end portion of the material, a
plurality of recessed portions or a plurality of protruding
portions corresponding to the protruding portions or the recessed
portions provided to the lower mold are provided to the upper mold,
and a plurality of minute protrusions are molded on a surface of
the longitudinal end portion of the material by the protruding
portions or the recessed portions provided to the lower mold and
the recessed portions or the protruding portions provided to the
upper mold during press molding with the upper mold and the lower
mold.
[0011] According to another aspect of the invention, there is
provided a mold for hot pressing, the mold including an upper mold
and a lower mold, for sandwiching a heated material between the
upper mold and the lower mold to press-mold the material, and for
holding the material in the mold to cool the material, wherein a
flange bending from the upper mold toward the lower mold or from
the lower mold toward the upper mold is molded at a longitudinal
end of the material by the upper mold and the lower mold during the
press molding.
Advantageous Effects of Invention
[0012] According to the invention, it is possible to suppress
thermal contraction of a material during cooling in hot press
molding to thereby avoid defects associated therewith.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic diagram of a hot press machine.
[0014] FIG. 2 is a perspective view of a hot press molded
article.
[0015] FIG. 3 is a longitudinal sectional view of a mold for hot
pressing.
[0016] FIG. 4 is a longitudinal sectional view of another
embodiment of the mold for hot pressing.
[0017] FIGS. 5(a) and 5(b) are diagrams showing another embodiment
of the hot press molded article.
DESCRIPTION OF EMBODIMENTS
[0018] As shown in FIG. 1, a hot press machine includes a mold 1
for hot pressing. The mold 1 for hot pressing has an upper mold 10
and a lower mold 20 and press-molds a material 2 by sandwiching the
material 2 between the upper mold 10 and the lower mold 20. The
upper mold 10 is supported on a moving device and movable in a
vertical direction. The lower mold 20 is fixed immovably.
[0019] The material 2 is metal material such as steel which can be
quenched. The material 2 is charged into the mold 1 for hot
pressing after heated to a quenching or higher temperature by
electric heating or the like. The material 2 is molded into a
predetermined product shape (see FIG. 2) by press molding with the
mold 1 for hot pressing and held for a predetermined time in the
mold to thereby be cooled and quenched (hot press-molded).
[0020] As shown in FIG. 2, the material 2 is molded from a
rectangular shape having one direction in a longitudinal direction
into a molded article 3 having a hat-shaped section continuous
along the longitudinal direction by the hot press molding. In other
words, by bending molding of the material 2 along a short-side
direction with the mold 1 for hot pressing, the material 2 is
molded into the molded article 3 having the hat-shaped section.
[0021] As the molded article 3 formed by using the mold 1 for hot
pressing according to the embodiment, there are a rocker outer and
the like besides a pillar outer shown in FIG. 2.
[0022] As shown in FIG. 2, protrusions 30, 30, . . . are molded on
a top face at longitudinal opposite end portions of the molded
article 3. The protrusions 30 are molded by curving molding of
portions of the material 2. In other words, the protrusions 30 are
shape changes including the curved portion inclined with respect to
the longitudinal direction of the material 2. The plurality of
protrusions 30 are molded as minute protrusions protruding upward
(or downward) into hemispherical shapes from a flat face of the
material 2.
[0023] The protrusions 30, 30, . . . are molded on the top face of
the molded article 3 and sprinkled at predetermined intervals in
the longitudinal direction and the short-side direction. Size,
shape, and the number of protrusions 30, 30, . . . are set so as
not to hinder mounting operation, assembly operation, and the like
in later steps, for example, i.e., not to impair the function of
the molded article 3 as a product.
[0024] As described above, the minute protrusions 30 are
protrusions having three-dimensional shapes such as hemispheres,
oval hemispheres, cubes, rectangular parallelepiped, and frustums
formed in such size as not to impair the function of the molded
article 3 as the product and protruding to a front face side or a
back face side from the flat face portion (especially, the flat
face extending in the longitudinal direction) of the molded article
3. The number of protrusions 30 to be provided is set so as to be
able to impart sufficient resistance to thermal contraction force
in the longitudinal direction of the material 2 in view of the
shape and the size.
[0025] For example, protruding lengths of the protrusions 30 from
the surface are preferably equal to or shorter than thickness of
the material 2. If the thickness of the material 2 is 1.4 mm,
diameters of the protrusions 30 formed into the hemispherical
shapes are preferably 3 mm or smaller.
[0026] As shown in FIG. 3, recessed portions 11, 11, . . . recessed
upward are formed on the upper mold 10 and protruding portions 21,
21, . . . protruding upward are formed on the lower mold 20. These
recessed portions 11, 11, . . . and the protruding portions 21, 21,
. . . are provided to mold the protrusions 30, 30, . . . on the
material 2 and have shapes corresponding to the protrusions 30, 30,
. . . . The respective protrusions 30 are molded by sandwiching
portions of longitudinal opposite end portions of the material 2
between the respective recessed portions 11 and the respective
protruding portions 21 in the press molding.
[0027] By sandwiching the material 2 between the upper mold 10 and
the lower mold 20 to mold the protrusions 30, 30, . . . in this
manner and then holding the material 2 in the mold for a
predetermined time to thereby cool the material 2, the hot press
molded article 3 is obtained.
[0028] As described above, in the embodiment, the protrusions 30,
30, . . . are formed by sandwiching the material 2 between the
recessed portions 11, 11, . . . of the upper mold 10 and the
protruding portions 21, 21, . . . of the lower mold 20 during the
press molding with the mold 1 for hot pressing, i.e., before
cooling in the mold proceeds and the material 2 is hot press-molded
into the molded article 3.
[0029] Here, when the heated metal material is cooled, the material
contracts from the longitudinal opposite end portions toward a
central portion and an amount of contraction in the longitudinal
direction is greater than that in the short-side direction, in
general. To cope with this, if the protrusions 30, 30, . . . are
formed on the longitudinal opposite end portions and shapes of the
opposite end portions are changed to be inclined with respect to a
direction of the flat face of the material 2, it is possible to
impart resistance to contraction force to contraction starting
points. Therefore, it is possible to satisfactorily prevent the
contraction in the longitudinal direction during cooling to thereby
prevent deformation and biting into the mold.
[0030] Since the protrusions 30, 30, . . . are formed as the minute
protrusions, they do not affect the product strength, deformation
mode, and the like. In other words, the protrusions 30, 30, . . .
do not greatly increase cross-sectional moment of the shape of the
product and do not serve as points where bending starts. In this
manner, the protrusions 30, 30, . . . do not impose a large
limitation on the shape of the product and it is easy to design the
molded article 3 including the protrusions 30, 30, . . . .
[0031] From a viewpoint of prevention of the contraction, the
protrusions 30, 30, . . . are preferably close to the longitudinal
ends as far as the protrusions 30, 30, . . . are formed in
positions as not to impair functions of the molded article 3. Here,
"the positions as not to impair functions of the molded article 3"
are positions where the molded article 3 does not affect the
product strength and the deformation mode of the molded article
3.
[0032] If the product shape of the molded article 3 includes a
hole, a notch, or the like on the top face or a side wall portion,
the protrusions 30, 30, . . . are formed in positions closer to the
end portions than positions where the hole or the notch is
provided.
[0033] In general, when the above-mentioned hole or notch is
provided to the molded article 3, it is often formed simultaneously
in the hot press molding and a processing blade such as a trim
punch for this purpose is provided in the mold in many cases. By
providing the protrusions 30, 30, . . . on the outer sides (on the
end portion sides when seen from the central portion) of the shape
change as in the embodiment, it is possible to prevent thermal
contraction in an area on an inner inside of the protrusions 30, 30
. . . . Therefore, the protrusions 30, 30, . . . do not affect
positions or dimensions of the hole and the notch and it is
possible to improve processing quality.
[0034] In the case where the product shape of the molded article 3
is the rocker outer, if protrusions 30, 30, . . . are molded based
on the same technical idea, it is possible to satisfactorily
prevent the contraction in the longitudinal direction during
cooling to thereby prevent deformation and biting into the
mold.
[0035] Although the protrusions 30, 30, . . . have been explained
as being protruding from the lower mold 20 toward the upper mold 10
(upward) in the above embodiment, they may protrude from the upper
mold 10 toward the lower mold 20 (downward) and their protruding
directions are not restricted.
[0036] The protruding directions of the respective protrusions 30
may be selected according to the function of the molded article 3.
In other words, the upward and downward protruding directions of
the protrusions 30 may be mixed.
[0037] As shown in FIG. 4, in place of the protrusions 30, 30, . .
. , flanges 40, 40 may be provided to longitudinal opposite ends of
the molded article 3. In the embodiment, in the same manner as in
the embodiment in which the protrusions 30, 30, . . . are molded,
portions bent with respect to a longitudinal direction (flat face
direction) of a material 2 are molded at longitudinal end portions
of the material 2 in press molding and resistance to contraction
force in the longitudinal direction is imparted.
[0038] The flanges 40, 40 are molded by bending the longitudinal
opposite ends of the material 2 downward (or upward). The
respective flanges 40 are provided to opposite ends of the molded
article 3 as inclined faces having angles which are larger than
45.degree. and which are such angles that the flanges 40 can be
molded by press molding with respect to the flat face direction of
the material 2. The flanges 40 are preferably molded as the
inclined faces having the angles from 60.degree. to 80.degree..
[0039] The flanges 40, 40 may be bent from the upper mold 10 toward
the lower mold 20 as shown in FIG. 4 or in an opposite direction
from the lower mold 20 toward the upper mold 10.
[0040] By bending and molding the longitudinal opposite ends of the
material 2 in this manner, a longitudinal length of the molded
article 3 is kept as a length between the flanges 40, 40 and
resistance to contraction force in the longitudinal direction can
be imparted. Therefore, it is possible to prevent the contraction
in the longitudinal direction during cooling to thereby prevent
deformation and biting into the mold.
[0041] The longitudinal opposite ends on which the flanges 40, 40
are molded are trimmed in a later step to be used as an end product
or parts of the product shape.
[0042] As a product shape of the molded article 3, shapes with open
longitudinal end faces may be employed as well. For example, as
shown in FIGS. 5(a) and 5(b), a shape having a simple hat-shaped
section continuous in a longitudinal direction (FIG. 5(a)) and a
shape having a substantially hat-shaped section, with a wall face
molded as an inclined face, continuous in a longitudinal direction
(FIG. 5(b)) may be employed.
DESCRIPTION OF NUMERALS
[0043] 1: mold for hot pressing, 2: material, 3: molded article,
10: upper mold, 11: recessed portion, 20: lower mold, 21:
protruding portion, 30: protrusion, 40: flange
* * * * *