U.S. patent application number 16/352732 was filed with the patent office on 2019-07-11 for method for joining members.
This patent application is currently assigned to KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.). The applicant listed for this patent is KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.). Invention is credited to Jiro IWAYA, Hideto KATSUMA, Yasuhiro MAEDA, Junya NAITOU.
Application Number | 20190210088 16/352732 |
Document ID | / |
Family ID | 56691031 |
Filed Date | 2019-07-11 |
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United States Patent
Application |
20190210088 |
Kind Code |
A1 |
MAEDA; Yasuhiro ; et
al. |
July 11, 2019 |
METHOD FOR JOINING MEMBERS
Abstract
In the present invention, a method for joining members involves
preparing a steel component having a bottom wall in which a hole is
provided, and a hollow aluminum pipe. The aluminum pipe is slipped
through the hole in the steel component and passed through the
bottom wall, rubber is inserted into the interior of the aluminum
pipe, and the rubber is compressed in the direction of the axis (L)
of the aluminum pipe and induced to distend towards the outside
from the inside. As a result of the foregoing, at least a section
of the aluminum pipe slipped through the hole is induced to undergo
expansion and is joined by clinching to the bottom wall. This
method for joining members reduces the load on the members,
improves the joint strength, and enables two members to be joined
at reduced cost.
Inventors: |
MAEDA; Yasuhiro; (Kobe-shi,
JP) ; IWAYA; Jiro; (Nagoya-shi, JP) ; NAITOU;
Junya; (Kobe-shi, JP) ; KATSUMA; Hideto;
(Kobe-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.) |
Hyogo |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA KOBE SEIKO SHO
(KOBE STEEL, LTD.)
Hyogo
JP
|
Family ID: |
56691031 |
Appl. No.: |
16/352732 |
Filed: |
March 13, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15546021 |
Jul 25, 2017 |
|
|
|
PCT/JP2016/050046 |
Jan 4, 2016 |
|
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16352732 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21D 39/206 20130101;
B21D 39/20 20130101; B21D 39/06 20130101; B21D 39/032 20130101 |
International
Class: |
B21D 39/06 20060101
B21D039/06; B21D 39/20 20060101 B21D039/20; B21D 39/03 20060101
B21D039/03 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2015 |
JP |
2015-022573 |
Jun 19, 2015 |
JP |
2015-124075 |
Claims
1. A method for joining members, comprising: preparing a first
member and a hollow second member, the first member having a first
section provided with a first hole; fitting the second member into
the first hole in the first member so as to cause the second member
to extend through the first section; inserting an elastic body into
the second member; compressing the elastic body in a direction of
an axis of the second member so as to cause the elastic body to
expand from an inner side toward an outer side, and thus causing at
least a part of the second member fitted in the first hole to
expand so as to become clinched to the first section; and wherein
the first member has a convex bead part, which arounds the first
hole and extends in axial direction of the surface of the first
member; and the convex bead part is fitted to second member to be
expanded together with second member.
2. The method for joining members according to claim 1, wherein a
shape of the first hole in the first member is analogous to a
cross-sectional shape of the part of the second member fitted in
the first hole.
3. The method for joining members according to claim 1, wherein an
outer-frame mold is disposed at the outer side of the second
member, and at least a part of the second member is formed to
extend along the outer-frame mold so as to become clinched.
4. The method for joining members according to claim 1, wherein an
outer-frame mold is disposed at the outer side of the second
member, and clinching is performed while partially limiting
expansion of the second member by using the outer-frame mold.
5. The method for joining members according to claim 1, wherein the
second member is also compressed in the direction of the axis when
the elastic body is compressed.
6. The method for joining members according to claim 1, wherein an
edge of the first hole is burred.
7. The method for joining members according to claim 1, wherein a
surface different from a surface provided with the first hole has a
bead section protruding in the direction of the axis, and clinching
is performed by including the bead section.
8. The method for joining members according to claim 1, wherein the
first member includes a second section having a second hole and is
clinched to the second member at the first hole and the second
hole.
9. The method for joining members according to claim 1, wherein the
elastic body is split at a joining section between the first member
and the second member.
10. The method for joining members according to claim 1, wherein a
plate is inserted between split pieces of the elastic body.
11. The method for joining members according to claim 1, wherein
the second member includes an outer wall provided with a partition
wall therein and extending in the direction of the axis, and
wherein clinching is performed by inserting a plurality of the
elastic bodies in spaces partitioned by the partition wall.
12. The method for joining members according to claim 1, wherein
the second member includes an end surface inclined relative to the
axis, and wherein opposite end surfaces of the elastic body in the
direction of the axis are parallel to the inclined surface.
13. The method for joining members according to claim 1, wherein
the first member includes an upright wall parallel to the axis, and
wherein clinching is performed while restraining deformation of the
upright wall by using a fixation jig.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of U.S. patent application
Ser. No. 15/546,021 filed Jul. 25, 2017, which is the U.S. National
Phase of International Application No. PCT/JP2016/050046 filed Jan.
4, 2016, which claims priority from Japanese Patent Application
Nos. 2015-124075 filed Jun. 19, 2015 and 2015-022573 filed Feb. 6,
2015.
TECHNICAL FIELD
[0002] The present invention relates to methods for joining
members.
BACKGROUND ART
[0003] In order to achieve weight reduction and improved safety in
automobiles, high-strength steel sheets composed of so-called
high-tensile steel are used. Although effective for weight
reduction and improved safety, such high-tensile steel is still
heavy compared with low specific gravity materials, such as
aluminum. Moreover, high-tensile steel is problematic in terms of
low formability due to its high strength, increasing forming load,
and also low dimensional accuracy. In order to solve these
problems, a multi-material process that involves using a steel
component together with an extruded product, a molded product, or a
press-formed product that use aluminum, which has lower specific
gravity than steel sheets, has been performed in recent years.
[0004] A problem with this multi-material process is in the joining
of the steel component and the aluminum component. In the welding
technology typified by spot-welding, fragile intermetallic
compounds (IMC) occur at the interface between the steel sheet and
the aluminum sheet. Thus, joining techniques, such as an
electromagnetic-forming joining technique, a screw-fastening
technique typified by bolts and nuts, a friction-stir-welding (FSW)
technique, a riveting technique, a self-piercing-riveting (SPR)
technique, a mechanical clinching technique, and a bonding
technique, are put to practical use.
[0005] A clinching process based on electromagnetic forming
involves inserting a solenoid forming coil into a pipe-shaped
component fitted to a counterpart component and causing induced
current to occur in the pipe serving as a conductor in accordance
with a changing magnetic field occurring as a result of applying
impulse current to the coil. An electromagnetic force is generated
between the magnetic field caused by primary current in the coil
and the induced current flowing oppositely in the circumferential
direction of the pipe, and the pipe receives an outward force and
thus expands, thereby becoming clinched to the counterpart
component. This joining method is suitable for copper and aluminum,
which have high electric conductivity, and is put to practical use
in some techniques for joining together automobile components.
[0006] Patent Literature 1 discloses a clinching technique based on
electromagnetic forming for performing a multi-material process. In
Patent Literature 1, a bumper reinforcement member formed of a
metallic material that is hollow in cross section is caused to
expand by electromagnetic forming and is engaged with holes
provided in a bumper stay composed of an aluminum alloy so as to be
joined thereto.
CITATION LIST
Patent Literature
[0007] PTL 1: Japanese Unexamined Patent Application Publication
No. 2007-284039
SUMMARY OF INVENTION
Technical Problem
[0008] As in Patent Literature 1, electromagnetic forming is
suitable for clinching a hollow component composed of copper or
aluminum having high electric conductivity to a counterpart
component, and a circular shape is preferred due to this joining
mechanism.
[0009] However, the joining technique based on electromagnetic
forming requires that the inner diameter of the solenoid coil to be
used be smaller than that of the aluminum component (i.e., aluminum
pipe). When the diameter of a coil is to be reduced when joining
together small-diameter components, there are problems in terms of
difficulties in manufacturing of the coil, as well as performance
and durability thereof. With regard to difficulties in
manufacturing, it is difficult to form a conductor into the shape
of a coil, leading to stricter limitations with respect to the
material and the cross-sectional shape of the conductor. In
addition, the conductor cross-sectionally deforms when being formed
into the shape of a coil. Moreover, a new capital investment
becomes necessary, such as requiring a large-capacity high-voltage
capacitor. Furthermore, the joining is not possible if the aluminum
component has an angular cross-sectional shape, a hole, or a
slit.
[0010] An object of the present invention is to provide a method
for joining members, by which two members can be joined together at
low cost while reducing the load on the members and increasing the
joint strength.
Solution to Problem
[0011] The present invention provides a joining method including:
preparing a first member and a hollow second member, the first
member having a first section provided with a first hole; fitting
the second member into the first hole in the first member so as to
cause the second member to extend through the first section;
inserting an elastic body into the second member; and compressing
the elastic body in a direction of an axis of the second member so
as to cause the elastic body to expand from an inner side toward an
outer side, and thus causing at least a part of the second member
fitted in the first hole to expand so as to become clinched to the
first section.
[0012] According to this method, the elastic body is caused to
expand outward so that the second member expands uniformly, thereby
preventing local deformation and reducing the load on the members.
This is because the second member can be uniformly deformed by
utilizing the properties in which the elastic body compressed in
the direction of the axis expands uniformly from the inner side
toward the outer side. Therefore, fit accuracy can be improved,
thereby achieving increased joint strength. Moreover, this is an
easier method, as compared with an electromagnetic forming method
or other machining methods. An electromagnetic forming method is
usable only on electrically conductive materials and has
limitations with respect to cross-sectional shapes and dimensions
depending on coils to be used. In contrast, this method is not
dependent on materials and has no limitations related to
cross-sectional shapes and dimensions. Moreover, since the method
is executable in a facility that applies a compressive force to the
elastic body, an electrical facility that requires a large-capacity
capacitor is not necessary. Consequently, the two members can be
joined together at low cost.
[0013] Furthermore, a shape of the first hole in the first member
may be analogous to a cross-sectional shape of the part of the
second member fitted in the first hole.
[0014] According to this method, the first member and the second
member have shapes analogous to each other so that the joining
process can be performed by causing the second member to expand
uniformly, thereby preventing local load from occurring in the
first member and the second member.
[0015] Furthermore, an outer-frame mold may be disposed at the
outer side of the second member, and at least a part of the second
member may be formed to extend along the outer-frame mold so as to
become clinched.
[0016] According to this method, the second member can be deformed
to a freely-chosen shape by using outer-frame molds with various
inner-surface shapes. The deformation shape can be appropriately
selected in view of, for example, component performance and can be
set in accordance with the intended purpose.
[0017] Furthermore, an outer-frame mold may be disposed at the
outer side of the second member, and clinching may be performed
while partially limiting expansion of the second member by using
the outer-frame mold.
[0018] According to this method, by disposing the outer-frame mold,
an expanding region of the second member is regulated, so that the
expanding region can be controlled with high accuracy. This
expanding region refers to a region in which the second member
expands outward.
[0019] Furthermore, the second member may also be compressed in the
direction of the axis when the elastic body is compressed.
[0020] According to this method, the second member is also
compressed in the direction of the axis so as to assist with
outward expansion of the second member. Specifically, together with
the expanding force applied by the elastic body from the inner side
of the second member, the second member can be expanded more
reliably, thereby enabling clinching.
[0021] Furthermore, an edge of the first hole may be burred.
[0022] According to this method, the edge of the hole in the first
member is burred so that the strength of the hole and the first
section of the first member can be increased. Consequently, the
first member can be prevented from deforming, the second member can
be prevented from being damaged, and the joint strength between the
two members can be increased.
[0023] Furthermore, a surface different from a surface provided
with the first hole may have a bead section protruding in the
direction of the axis, and clinching may be performed by including
the bead section.
[0024] According to this method, because clinching is performed by
including the bead section, the two members can be fixed to each
other more securely, and the joint strength therebetween can be
further increased. In particular, in a case where the second member
has a circular cross-sectional shape, the second member can be
prevented from rotating relative to the first member.
[0025] Furthermore, the first member may include a second section
having a second hole and may be clinched to the second member at
the first hole and the second hole.
[0026] According to this method, clinching is performed at two
locations so that the joint strength can be further increased, as
compared with the case where clinching is performed at a single
location.
[0027] Furthermore, the elastic body may be split at a joining
section between the first member and the second member.
[0028] According to this method, the elastic body is split at the
joining section so that deformation of the joining section of the
first member can be prevented. Specifically, the elastic body is
split such that the elastic body is not disposed near the joining
section, whereby the second member does not receive an expanding
force from the elastic body near the joining section and thus does
not expand near the joining section. Consequently, the first member
does not receive a force from the second member near the joining
section, so that the shape of the joining section can be
maintained.
[0029] Furthermore, a plate may be inserted between split pieces of
the elastic body.
[0030] According to this method, the plate exists in the joining
section so that deformation of the joining section of the first
member can be prevented more reliably. Because the plate does not
expand even by receiving a compressive force in the direction of
the axis, an expanding force is not applied to the joining section,
so that the joining section can maintain its original shape more
reliably.
[0031] Furthermore, the second member may include an outer wall
provided with a partition wall therein and extending in the
direction of the axis, and clinching may be performed by inserting
a plurality of the elastic bodies in spaces partitioned by the
partition wall.
[0032] According to this method, because the clinching process is
performed by using the plurality of elastic bodies, concentration
of stress caused by deformation can be prevented, so that the load
on the first member and the second member can be reduced.
[0033] Furthermore, the second member may include an end surface
inclined relative to the axis, and opposite end surfaces of the
elastic body in the direction of the axis may be parallel to the
inclined surface.
[0034] Accordingly, this method can be used for clinching the first
member and the second member together in an inclined state, which
is often seen from a practical standpoint. In particular, opposite
end surfaces of the elastic body are given the same angle as the
joining angle, so that the elastic body expands uniformly, whereby
the second member can be expanded uniformly.
[0035] Furthermore, the first member may include an upright wall
parallel to the axis, and clinching may be performed while
restraining deformation of the upright wall by using a fixation
jig.
[0036] According to this method, deformation of the first member is
restrained by the jig, so that deformation of the first member
caused by expansion of the second member can be suppressed.
Advantageous Effects of Invention
[0037] According to the present invention, the second member is
caused to expand uniformly by causing the elastic body to expand
from the inner side toward the outer side, thereby preventing local
deformation and reducing the load on the members. Therefore, fit
accuracy can be improved, thereby achieving increased joint
strength. Moreover, since this is an easier method, as compared
with an electromagnetic forming method or other machining methods,
the two members can be joined together at low cost.
BRIEF DESCRIPTION OF DRAWINGS
[0038] FIG. 1A is a perspective view of a channel-type steel
component having a circular hole and an aluminum pipe having a
circular cross-sectional shape.
[0039] FIG. 1B is a perspective view of the steel component and the
aluminum pipe in FIG. 1A in a clinched state.
[0040] FIG. 2A is a cross-sectional view illustrating a state
before a clinching process according to a first embodiment of the
present invention.
[0041] FIG. 2B is a cross-sectional view illustrating a state where
the clinching process according to the first embodiment of the
present invention is being performed.
[0042] FIG. 2C is a cross-sectional view illustrating a state after
the clinching process according to the first embodiment of the
present invention.
[0043] FIG. 2D is a cross-sectional view illustrating a state where
a rubber piece is being pulled out after the clinching process
according to the first embodiment of the present invention.
[0044] FIG. 3A is a cross-sectional view illustrating a state
before the clinching process when a rubber piece according to a
modification of the first embodiment of the present invention is a
fluid sealing member.
[0045] FIG. 3B is a cross-sectional view illustrating a state after
the clinching process when the rubber piece according to the
modification of the first embodiment of the present invention is a
fluid sealing member.
[0046] FIG. 4A is a perspective view of a steel component having a
circular hole and an aluminum pipe having a rectangular
cross-sectional shape.
[0047] FIG. 4B is a perspective view of a steel component having a
rectangular hole and an aluminum pipe having a circular
cross-sectional shape.
[0048] FIG. 5A is a cross-sectional view of an example of a joining
section of a steel component having undergone a burring
process.
[0049] FIG. 5B is a cross-sectional view of another example of a
joining section of a steel component having undergone a burring
process.
[0050] FIG. 5C is a cross-sectional view of another example of a
joining section of a steel component having undergone a burring
process.
[0051] FIG. 6A is a perspective view of a joining section of a
steel component having a circular hole having undergone a burring
process.
[0052] FIG. 6B is a perspective view of a joining section of a
steel component having a rectangular hole having undergone a
burring process.
[0053] FIG. 7A is a cross-sectional view illustrating a state
before a clinching process performed by using an outer-frame mold
according to a second embodiment of the present invention.
[0054] FIG. 7B is a cross-sectional view illustrating a state after
the clinching process performed by using the outer-frame mold
according to the second embodiment of the present invention.
[0055] FIG. 8A is a perspective view of an aluminum pipe formed
into a cylindrical tube shape.
[0056] FIG. 8B is a perspective view of an aluminum pipe formed
into a hexagonal tube shape.
[0057] FIG. 8C is a perspective view of an aluminum pipe formed
into a cross tube shape.
[0058] FIG. 9A is a cross-sectional view illustrating a state
before a clinching process performed by disposing a rubber piece
only near a joining section in accordance with a third embodiment
of the present invention.
[0059] FIG. 9B is a cross-sectional view illustrating a state after
the clinching process performed by disposing the rubber piece only
near the joining section in accordance with the third embodiment of
the present invention.
[0060] FIG. 10A is a cross-sectional view illustrating a state
before a clinching process in which an aluminum pipe is partially
expanded by using an outer-frame mold according to a modification
of the third embodiment of the present invention.
[0061] FIG. 10B is a cross-sectional view illustrating a state
after the clinching process in which the aluminum pipe is partially
expanded by using the outer-frame mold according to the
modification of the third embodiment of the present invention.
[0062] FIG. 11A is a cross-sectional view illustrating a state
before a clinching process performed by using a
truncated-cone-shaped indenter according to a fourth embodiment of
the present invention.
[0063] FIG. 11B is a cross-sectional view illustrating a state
after the clinching process performed by using the
truncated-cone-shaped indenter according to the fourth embodiment
of the present invention.
[0064] FIG. 12A is a cross-sectional view illustrating a state
before a clinching process performed by compressing an aluminum
pipe according to a fifth embodiment of the present invention in an
axial direction.
[0065] FIG. 12B is a cross-sectional view illustrating a state
after the clinching process performed by compressing the aluminum
pipe according to the fifth embodiment of the present invention in
the axial direction.
[0066] FIG. 13A is a cross-sectional view illustrating a state
before a clinching process performed by using an indenter equipped
with an outer frame in accordance with a modification of the fifth
embodiment of the present invention.
[0067] FIG. 13B is a cross-sectional view illustrating a state
after the clinching process performed by using the indenter
equipped with the outer frame in accordance with the modification
of the fifth embodiment of the present invention.
[0068] FIG. 14A is a perspective view of a steel component having a
circular hole and an aluminum pipe having a circular
cross-sectional shape when the two are clinched together at two
locations in accordance with a sixth embodiment of the present
invention.
[0069] FIG. 14B is a perspective view of a steel component having a
rectangular hole and an aluminum pipe having a rectangular
cross-sectional shape when the two are clinched together at two
locations in accordance with the sixth embodiment of the present
invention.
[0070] FIG. 15A is a perspective view of a hat-channel-type steel
component having a circular hole and an aluminum pipe having a
circular cross-sectional shape when the two are clinched together
at two locations in accordance with a modification of the sixth
embodiment of the present invention.
[0071] FIG. 15B is a perspective view of a hat-channel-type steel
component having a rectangular hole and an aluminum pipe having a
rectangular cross-sectional shape when the two are clinched
together at two locations in accordance with a modification of the
sixth embodiment of the present invention.
[0072] FIG. 16 is a cross-sectional view illustrating a state where
the clinching process in FIGS. 15A and 15B is being performed.
[0073] FIG. 17A is a cross-sectional view illustrating a state
after the clinching process in FIG. 16A.
[0074] FIG. 17B is a cross-sectional view illustrating a state
after the clinching process in FIG. 16A is performed by partial
expansion.
[0075] FIG. 18A is a cross-sectional view illustrating a state
after a steel component and an aluminum pipe are clinched together
at surfaces having bead sections in accordance with a modification
of a seventh embodiment of the present invention.
[0076] FIG. 18B is a cross-sectional view taken along line
XVIII-XVIII in FIG. 18A.
[0077] FIG. 19 is a cross-sectional view illustrating a state after
a clinching process performed by using split rubber pieces
according to an eighth embodiment of the present invention.
[0078] FIG. 20A is a cross-sectional view illustrating a state
after a clinching process performed by inserting a plate between
split rubber pieces in accordance with a modification of the eighth
embodiment of the present invention.
[0079] FIG. 20B is a cross-sectional view illustrating a state
after a clinching process performed by using a rubber piece with a
different hardness at a joining section in accordance with a
modification of the eighth embodiment of the present invention.
[0080] FIG. 21A is a perspective view illustrating a state before a
resinous tube component and an aluminum pipe according to a ninth
embodiment of the present invention are clinched together.
[0081] FIG. 21B is a perspective view illustrating a state after
the resinous tube component and the aluminum pipe in FIG. 21A are
clinched together.
[0082] FIG. 22A is a cross-sectional view illustrating the state
before the resinous tube component and the aluminum pipe in FIG.
21A are clinched together.
[0083] FIG. 22B is a cross-sectional view illustrating the state
after the resinous tube component and the aluminum pipe in FIG. 21A
are clinched together.
[0084] FIG. 23 is a perspective view of a steel bumper beam and an
aluminum stay according to a tenth embodiment of the present
invention.
[0085] FIG. 24A is a cross-sectional view of a bulging jig
according to the tenth embodiment of the present invention.
[0086] FIG. 24B is a cross-sectional view of a steel bumper beam
and an aluminum stay having the bulging jig inserted therein,
according to the tenth embodiment of the present invention.
[0087] FIG. 25A is a cross-sectional view illustrating a state
before a clinching process according to the tenth embodiment of the
present invention.
[0088] FIG. 25B is a cross-sectional view illustrating a state
after the clinching process according to the tenth embodiment of
the present invention.
[0089] FIG. 26A is a cross-sectional view illustrating a state
where the bulging jig has been removed after the clinching process
according to the tenth embodiment of the present invention.
[0090] FIG. 26B is a cross-sectional view taken along line
XXVI-XXVI in FIG. 26A.
[0091] FIG. 27A is a perspective view of an aluminum pipe according
to an eleventh embodiment of the present invention.
[0092] FIG. 27B is a cross-sectional view illustrating a state
before a clinching process, taken along line XXVI-XXVI in FIG.
27A.
[0093] FIG. 27C is a cross-sectional view illustrating a state
after the clinching process, taken along line XXVI-XXVI in FIG.
27A.
[0094] FIG. 27D is a plan view of the aluminum pipe and rubber
pieces according to the eleventh embodiment of the present
invention.
[0095] FIG. 27E is a plan view of the aluminum pipe and rubber
pieces with a different shape, according to the eleventh embodiment
of the present invention.
[0096] FIG. 27F is a plan view of the aluminum pipe, rubber pieces,
and L-shaped angles according to the eleventh embodiment of the
present invention.
[0097] FIG. 28A is a cross-sectional view illustrating a state
before a clinching process according to a twelfth embodiment of the
present invention.
[0098] FIG. 28B is a cross-sectional view illustrating a state
after the clinching process according to the twelfth embodiment of
the present invention.
[0099] FIG. 29A is a plan view illustrating a state before and
after a clinching process according to a thirteenth embodiment of
the present invention.
[0100] FIG. 29B is a plan view illustrating a state before and
after the clinching process according to the thirteenth embodiment
of the present invention.
[0101] FIG. 29C is a front view illustrating a state before the
clinching process according to the thirteenth embodiment of the
present invention.
[0102] FIG. 29D is a front view illustrating a state after the
clinching process when a fixation jig according to the thirteenth
embodiment of the present invention is not used.
[0103] FIG. 29E is a front view illustrating a state after the
clinching process when the fixation jig according to the thirteenth
embodiment of the present invention is used.
DESCRIPTION OF EMBODIMENTS
[0104] Embodiments of the present invention will be described below
with reference to the appended drawings. In the following
description, terms that express directions and positions (such as
"upper side" and "lower side") are sometimes used, but these terms
are used for providing an easier understanding of the present
invention and are not to limit the technical scope of the
invention. Furthermore, the following description merely relates to
examples of embodiments of the present invention and is not
intended to limit the application or the purpose of the
invention.
[0105] Although materials of individual components are exemplified
in the embodiments described below, the materials of the components
in all of the embodiments are particularly not limited to the
exemplified materials, and the present invention is applicable to
arbitrary materials.
First Embodiment
[0106] A method for joining a steel component (first member) 10 and
an aluminum pipe (second member) 20 together by clinching will be
described with reference to FIGS. 1A to 2D.
[0107] As shown in FIG. 1A, the steel component 10 is composed of
high-tensile steel and has a shape of a channel. The steel
component 10 includes a bottom wall (first section) 11, two side
walls 12 and 13 extending vertically upward from the base wall 11,
and upper walls 14 extending horizontally outward from the two side
walls 12 and 13. The bottom wall 11 is provided with a hole (first
hole) 15 in which the aluminum pipe 20 is fittable. The aluminum
pipe 20 is composed of an aluminum alloy, has a hollow and circular
cross-sectional shape, and extends along an axis L. The axis L
extends through the center of the aluminum pipe 20 and through the
center of the hole 15 in the steel component 10.
[0108] As shown in FIG. 1B, with regard to the aluminum pipe 20 and
the steel component 10, the aluminum pipe 20 expands from the inner
side toward the outer side so that an upper edge 21 thereof in the
drawing is pressed and bent, whereby the aluminum pipe 20 becomes
clinched to the hole 15 in the steel component 10. The hole 15 in
the steel component 10 preferably has a shape analogous to the
cross-sectional shape of the aluminum pipe 20 and a size that is as
small as possible within a range in which the aluminum pipe 20 is
fittable therein.
[0109] The steel component 10 and the aluminum pipe 20 are clinched
together in accordance with the following procedure.
[0110] As shown in FIGS. 2A to 2D, the steel component 10 and the
aluminum pipe 20 are clinched together by using a rubber piece
(elastic body) 30.
[0111] First, as shown in FIG. 2A, the aluminum pipe 20 is fitted
into the hole 15 in the steel component 10, the rubber piece 30 is
inserted into the aluminum pipe 20, and the components are set in a
pressing device 40. Alternatively, the aluminum pipe 20 may be
fitted into the hole 15 in a state where the rubber piece 30 is
inserted in the aluminum pipe 20. The pressing device 40 includes
an indenter 43 and a strike plate 42. The indenter 43 has a flat
lower surface and uses the lower surface to press against the steel
component 10 or the rubber piece 30. The strike plate 42 has a flat
upper surface, and the steel component 10 and the rubber piece 30
are placed on the upper surface. The rubber piece 30 has a columnar
shape with a diameter that allows it to be insertable into the
aluminum pipe 20, and has an overall length that is larger than
that of the aluminum pipe 20. Therefore, when in the set state, the
rubber piece 30 partially protrudes from the upper end of the
aluminum pipe 20. Thus, when the pressing device 40 begins pressing
such that the strike plate 42 and the indenter 43 relatively
approach each other, the rubber piece 30 is pressed first. However,
the rubber piece 30 does not necessarily have to protrude from the
upper end of the aluminum pipe 20, and may alternatively be flush
with the upper end of the aluminum pipe 20 or be accommodated
therein.
[0112] Next, as shown in FIG. 2B, the pressing device 40 applies a
compressive external force to the rubber piece 30 along the axis L.
The rubber piece 30 dimensionally enlarges in the diameter
direction as its size decreases along the axis L. Accordingly, the
rubber piece 30 is caused to elastically deform (expand) outward
from the axis L, thereby causing the aluminum pipe 20 to expand.
Then, as shown in FIG. 2C, the aluminum pipe 20 is further expanded
by being further compressed by the pressing device 40. At the same
time, the upper edge 21 in the drawing is pressed and bent toward
the steel component 10, so that the aluminum pipe 20 becomes
clinched to the steel component 10.
[0113] After the clinching process, the rubber piece 30 from which
the compressive force of the pressing device 40 has been removed
restores its original shape with its own elastic force, as shown in
FIG. 2D, so that the rubber piece 30 can be readily removed from
the aluminum pipe 20.
[0114] According to this method, the rubber piece 30 is expanded
outward so that the aluminum pipe 20 expands uniformly, thereby
preventing local deformation and reducing the load on the members
10 and 20. This is because the aluminum pipe 20 can be uniformly
deformed by utilizing the properties in which the rubber piece 30
compressed along the axis L expands uniformly from the inner side
toward the outer side. Therefore, fit accuracy can be improved,
thereby achieving increased joint strength. Moreover, this is an
easier method, as compared with an electromagnetic forming method
or other machining methods.
[0115] An electromagnetic forming method is usable only on
electrically conductive materials and has limitations with respect
to cross-sectional shapes and dimensions depending on coils to be
used. In contrast, this method is not dependent on materials and
has no limitations related to cross-sectional shapes and
dimensions. Moreover, since the method is executable in a facility
that applies a compressive force to the rubber piece 30, an
electrical facility that requires a large-capacity capacitor, as in
the electromagnetic forming method, is not necessary.
[0116] According to this method, two members can be joined
together, so that a multi-material process can be readily executed
at low cost. Therefore, as described above, this method can be used
on members composed of various materials other than the two
components composed of high-tensile steel and an aluminum alloy.
The same applies to the subsequent embodiments.
[0117] The material used as the rubber piece 30 to be inserted into
the aluminum pipe 20 is preferably, for example, urethane rubber,
chloroprene rubber, CNR rubber (chloroprene rubber+nitrile rubber),
or silicon rubber. Moreover, it is preferable that the rubber piece
30 have a Shore A hardness of 30 or higher.
[0118] A member to be inserted into the aluminum pipe 20 is not
limited to the rubber piece 30. For example, as shown in FIGS. 3A
and 3B, a fluid sealing member 32 having gas or liquid sealed
therein may be used in place of the rubber piece 30. Other members
that expand outward in accordance with a compressive force so as to
expand the aluminum pipe 20 are also usable. It is preferable that
the member deforms uniformly like the rubber piece 30 when
expanding outward in response to a compressive force.
[0119] Furthermore, as shown in FIGS. 4A and 4B, the shape and size
of the hole 15 provided in the bottom wall 11 of the steel
component 10 do not have to be analogous to the cross-sectional
shape of the aluminum pipe 20 to be fitted thereto. Specifically, a
steel component 10 having a circular hole 15 and an aluminum pipe
20 having a rectangular cross-sectional shape may be clinched
together as in FIG. 4A, or a steel component 10 having a
rectangular hole 15 and an aluminum pipe 20 having a circular
cross-sectional shape may be clinched together as in FIG. 4B.
[0120] Furthermore, as shown in FIGS. 5A to 5C, a burring process
(flange-up process) may be performed on the hole 15 for preventing
deformation of the steel component 10, for reducing damages to the
aluminum pipe 20, and for increasing the clinching strength.
Conceivable shapes obtained as a result of the burring process
include, for example, various cross-sectional shapes shown in FIGS.
5A to 5C. In FIG. 5A, a shoulder section 15a has a large radius. In
FIG. 5B, the shoulder section 15a is chamfered. In FIG. 5C, a
rolling process is employed. Accordingly, even in a case where the
steel component 10 has high strength, cracking of the steel
component 10 as a result of machining can be effectively
prevented.
[0121] The burring process may be performed in the upward direction
or the downward direction in the drawings. Preferably, as indicated
by a two-dot chain line in FIG. 2A, the burring process is
performed in the downward direction in the drawing such that a part
that is bent as a result of the burring process does not appear on
the top surface of the steel component 10.
[0122] As shown in FIGS. 6A and 6B, there are various conceivable
shapes, such as a circular shape (see FIG. 6A) or a rectangular
shape (see FIG. 6B), for the hole 15 that is to undergo the burring
process. In particular, in a case where the hole 15 is polygonal,
corner sections 15b may be cut out, and only straight side sections
15c may be bent upward, as shown in FIG. 6B, so that the corner
sections 15b can be prevented from cracking.
Second Embodiment
[0123] A joining method according to this embodiment shown in FIGS.
7A and 7B is similar to that in the first embodiment in FIGS. 2A to
2D except for a feature related to an outer-frame mold 41.
Therefore, parts identical to those in the configuration shown in
FIGS. 2A to 2D will be given the same reference signs, and
descriptions thereof will be omitted.
[0124] As shown in FIG. 7A, in this embodiment, the steel component
10 and the aluminum pipe 20 are clinched together by using the
outer-frame mold 41. The outer-frame mold 41 has a cylindrical
shape concentric with the aluminum pipe 20. The outer-frame mold 41
is disposed between the strike plate 42 and the steel component 10
and at the outer side of the aluminum pipe 20. When set in the
pressing device 40, the aluminum pipe 20 and the outer-frame mold
41 have a gap therebetween. By applying pressure using the indenter
43 in this state, the aluminum pipe 20 can conform to the shape of
the inner surface of the outer-frame mold 41 when the aluminum pipe
20 expands, as shown in FIG. 7B.
[0125] According to this method, as shown in FIGS. 8A to 8C, the
inner surface of the outer-frame mold 41 may have various polygonal
shapes, such as a hexagonal shape (see FIG. 8B) or a cross shape
(see FIG. 8C), in addition to the cylindrical shape (see FIG. 8A).
With regard to these shapes, an appropriate shape can be selected
in view of, for example, component performance. For example, if the
aluminum pipe 20 is a bumper stay, which is one of automobile
components, the inner surface of the outer-frame mold 41 may be
given small recesses and protrusions so that these small recesses
and protrusions are transferred onto the aluminum pipe 20, thereby
achieving enhanced performance for absorbing impact energy in the
event of a collision.
Third Embodiment
[0126] A joining method according to this embodiment shown in FIGS.
9A to 10B is similar to that in the first embodiment in FIGS. 2A to
2D except for a feature related to an expanding region 22 of the
aluminum pipe 20. Therefore, parts identical to those in the
configuration shown in FIGS. 2A to 2D will be given the same
reference signs, and descriptions thereof will be omitted.
[0127] As shown in FIG. 9A, in this embodiment, the rubber piece 30
to be inserted into the aluminum pipe 20 is reduced in length, such
that the rubber piece 30 is disposed only near the joining section
of the aluminum pipe 20. Moreover, the strike plate 42 has a
columnar protrusion 42a extending upward. The protrusion 42a is
inserted into the aluminum pipe 20 and supports the rubber piece
30. In other words, the lower end of the rubber piece 30 is in
contact with the upper end of the protrusion 42a, and the upper end
of the rubber piece 30 is in contact with the lower end of the
indenter.
[0128] According to this method, an outward expanding force does
not act on the part where the rubber piece 30 is not disposed.
Thus, as shown in FIG. 9B, the expanding region 22 of the aluminum
pipe 20 is limited, so that the aluminum pipe 20 and the steel
component 10 can be clinched together by causing only the region
near the joining section of the aluminum pipe 20 to expand.
Selection of whether the aluminum pipe 20 is to be substantially
entirely deformed as in the first and second embodiments described
above or whether the aluminum pipe 20 is to be partially deformed
as in this embodiment may be made, as appropriate, based on, for
example, the relationship with the component performance.
[0129] As shown in FIGS. 10A and 10B, a cylindrical outer-frame
mold 44 that regulates expansion of the aluminum pipe 20 may be
disposed therearound. The outer-frame mold 44 has, at the upper end
thereof, a large-diameter section 44a with a large inner diameter
near the joining section so as to expand only near the joining
section. The inner diameter excluding that of the large-diameter
section 44a is substantially equal to the outer diameter of the
aluminum pipe 20. Therefore, by using the outer-frame mold 44, the
expanding region 22 can be controlled with high accuracy such that
the aluminum pipe 20 expands only near the joining section.
Fourth Embodiment
[0130] A joining method according to this embodiment shown in FIGS.
11A and 11B is similar to that in the third embodiment in FIGS. 10A
and 10B except for a feature related to the shape of the indenter
43. Therefore, parts identical to those in the configuration shown
in FIGS. 10A and 10B will be given the same reference signs, and
descriptions thereof will be omitted.
[0131] As shown in FIG. 11A, the indenter 43 included in the
pressing device 40 according to this embodiment has a
downwardly-tapered truncated-cone shape and has a protrusion 43a
and a brim 43b. Sometimes, a high forming force is required for
expanding the edge 21 of the aluminum pipe 20 protruding upward
from the steel component 10, and there are cases where the
clinching is insufficient with the deformation of the rubber piece
30 alone or the durability of the rubber piece 30 may become a
problem due to large deformation thereof. In such cases, the method
according to this embodiment is effective.
[0132] As shown in FIG. 11B, at the final stage of the forming
process, the upper edge 21 of the aluminum pipe 20 protruding
upward from the steel component 10 is pressed and expanded outward
directly by the protrusion 43a of the indenter 43 without the
intervention of the rubber piece 30, and is further bent toward the
steel component 10. This enables more secure clinching. Moreover,
the durability of the rubber piece 30 is improved since excessive
load does not act on the rubber piece 30.
Fifth Embodiment
[0133] A joining method according to this embodiment shown in FIGS.
12A and 12B is similar to that in the first embodiment in FIGS. 2A
to 2D except for a feature related to the shapes of the indenter 43
and the strike plate 42. Therefore, parts identical to those in the
configuration shown in FIGS. 2A to 2D will be given the same
reference signs, and descriptions thereof will be omitted.
[0134] As shown in FIG. 12A, in this embodiment, the strike plate
42 includes a columnar protrusion 42a extending upward and a brim
42b provided around the protrusion 42a. The indenter 43 includes a
columnar protrusion 43a extending downward and a brim 43b provided
around the protrusion 43a. The protrusions 42a and 43a are inserted
in the aluminum pipe 20.
[0135] As shown in FIG. 12B, when performing pressing, the brims
42b and 43b come into contact with the respective ends of the
aluminum pipe 20. Thus, the brims 42b and 43b apply compressive
forces along the axis L onto the aluminum pipe 20.
[0136] According to this method, the aluminum pipe 20 is also
compressed along the axis L so as to assist with outward expansion
of the aluminum pipe 20. Specifically, together with the expanding
force applied by the rubber piece 30 from the inner side of the
aluminum pipe 20, the aluminum pipe 20 can be expanded more
reliably, thereby enabling clinching.
[0137] As shown in FIGS. 13A and 13B, it is also effective to
dispose an outer frame 45 at the outer side of a part of the
aluminum pipe 20 that is not to be expanded (i.e., the edge 21 in
this embodiment). The outer frame 45 is cylindrical and is disposed
around the edge 21 of the aluminum pipe 20. By disposing the outer
frame 45, deformation of the edge 21 of the aluminum pipe 20 is
regulated, so that a shape according to the intended use can be
obtained.
Sixth Embodiment
[0138] A joining method according to this embodiment shown in FIGS.
14A to 17B is similar to that in the first embodiment in FIGS. 2A
to 2D except for a feature related to the number of joining
sections. Therefore, parts identical to those in the configuration
shown in FIGS. 2A to 2D will be given the same reference signs, and
descriptions thereof will be omitted.
[0139] As shown in FIG. 14A, in this embodiment, the steel
component 10 and the aluminum pipe 20 are clinched together at two
locations. The steel component 10 includes a bottom wall 11, an
upper wall (second section) 14 disposed parallel to the bottom wall
11, and two side walls 12 and 13 connecting these walls, all of
which constitute a closed cross section. The bottom wall 11 is
provided with a hole 15 (first hole). The upper wall 14 is provided
with a hole 17 (second hole). As shown in FIG. 14B, the aluminum
pipe 20 is clinched to these two holes 15 and 17.
[0140] FIG. 16 is a cross-sectional view during a clinching
process. In the clinching process performed on the two holes 15 and
17, the indenter 43 is used to press and bend the edge 21 of the
aluminum pipe 20 toward the steel component 10 as in the first
embodiment, and the aluminum pipe 20 is further expanded so as to
be clinched to the upper hole 17 in the drawing. The aluminum pipe
20 is clinched to the lower hole 15 in the drawing by being simply
expanded.
[0141] By performing clinching at two locations as in this
embodiment, the joint strength can be further increased, as
compared with the case where clinching is performed at a single
location. In particular, the clinching method using the rubber
piece 30 is the same as the case where clinching is performed at a
single location in terms of the facility used, and is thus
effective since the method can easily be used when performing
clinching at a plurality of locations.
[0142] The shape of the steel component 10 or the aluminum pipe 20
when performing clinching at two locations is not limited to the
above. For example, the steel component 10 may have a hat-channel
shape, as shown in FIGS. 15A and 15B, or another shape.
[0143] Furthermore, as shown in FIG. 17A, the entire aluminum pipe
20 may be freely expanded when performing the clinching process. By
using the outer-frame mold 44 described with reference to FIGS. 7A
and 7B, only the regions of the aluminum pipe 20 near the joining
sections may be clinched by being expanded, as shown in FIG.
17B.
Seventh Embodiment
[0144] A joining method according to this embodiment shown in FIGS.
18A and 18B is similar to that in the sixth embodiment in FIG. 16
except for features related to joining locations and bead sections
12a and 13a. Therefore, parts identical to those in the
configuration shown in FIG. 16 will be given the same reference
signs, and descriptions thereof will be omitted.
[0145] As shown in FIGS. 18A and 18B, in the steel component 10
according to this embodiment, the two side walls 12 and 13 are
respectively provided with the bead sections 12a and 13a. The bead
sections 12a and 13a are inward protrusions and extend along the
axis L. The aluminum pipe 20 is entirely clinched to the hole 15 in
the bottom wall 11 and to the bead sections 12a and 13a of the two
side walls 12 and 13.
[0146] As shown in FIG. 18B, the aluminum pipe 20 and the steel
component 10 are clinched together by including the bead sections
12a and 13a of the side walls 12 and 13 so that the joint strength
can be further increased. Moreover, because the aluminum pipe 20
and the steel component 10 are clinched together by including the
bead sections 12a and 13a, rotation of the aluminum pipe 20
relative to the steel component 10 can be regulated. Accordingly,
the bead sections 12a and 13a are effective for preventing the
aluminum pipe 20 from rotating. Alternatively, for preventing the
aluminum pipe 20 from rotating, it is also effective to give the
edge of the hole 15 a cutout shape or a shape other than the
circular shape.
Eighth Embodiment
[0147] A joining method according to this embodiment shown in FIG.
19 is similar to that in the seventh embodiment in FIG. 18A except
for a feature related to split rubber pieces 30. Therefore, parts
identical to those in the configuration shown in FIG. 18A will be
given the same reference signs, and descriptions thereof will be
omitted.
[0148] As shown in FIG. 19, in this embodiment, the rubber piece 30
is split near the hole 15. According to this method, the rubber
piece 30 is split at the hole 15, that is, at the joining section,
so that deformation of the hole 15 and the bottom wall 11 of the
steel component 10 can be prevented. Specifically, because the
rubber piece 30 is split, an expanding force is not applied to the
hole 15, so that the hole 15 and the bottom wall 11 can maintain
their original shapes.
[0149] Furthermore, as shown in FIGS. 20A and 20B, it is preferable
that a tabular plate 31 be inserted between the rubber pieces 30
split at the joining section and inserted in the aluminum pipe 20.
The plate 31 may be composed of metal or resin so long as it is
strong enough not to deform in response to a compressive force
received from the rubber piece 30, and preferably has a thickness
of 15 mm or smaller.
[0150] According to this method, the plate 31 exists in the joining
section so that deformation of the hole 15 and the bottom wall 11
of the steel component 10 can be prevented more reliably. Because
the plate 31 does not expand, an expanding force is not applied to
the hole 15, so that the hole 15 and the bottom wall 11 can
maintain their original shapes.
[0151] As an alternative to FIG. 20A in which the rubber piece 30
is split and the plate 31 is disposed between the split pieces, a
rubber piece 30 partially composed of a different material may be
used, as in FIG. 20B. In FIG. 20B, the rubber piece is a non-split
single piece but has a high-hardness section 30a near the joining
section. Specifically, the rubber piece 30 has a high hardness only
in a part thereof near the joining section. Thus, this
high-hardness section 30a has a function similar to that of the
plate 31, so that the hole 15 and the bottom wall 11 can maintain
their original shapes.
Ninth Embodiment
[0152] A joining method according to this embodiment shown in FIGS.
21A to 22B is similar to that in the fifth embodiment in FIGS. 9A
and 9B except that the steel component 10 is replaced with a
cylindrical resinous tube component 50. Therefore, parts identical
to those in the configuration shown in FIGS. 9A and 9B will be
given the same reference signs, and descriptions thereof will be
omitted.
[0153] As shown in FIGS. 21A and 21B, in this embodiment, the
cylindrical resinous tube component 50 having a flange at the upper
end thereof and the aluminum pipe 20 are clinched together. Like
the resinous tube component 50, the target member does not have to
be tabular or be composed of metal. As mentioned above, the
aluminum pipe 20 deforms outward in response to a compressive force
applied along the axis L from the rubber piece 30 so as to expand.
Therefore, this method is not limited to be used on electrically
conductive materials, as in the electromagnetic forming method, and
can also be used on resin materials, and the shape is not limited
to the tabular shape.
[0154] FIGS. 22A and 22B are cross-sectional views illustrating
states before and after the resinous tube component and the
aluminum pipe in FIG. 21A are clinched together. As shown in FIGS.
22A and 22B, the aluminum pipe 20 is clinched to the cylindrical
resinous tube component 50 by being expanded at the opposite ends
thereof.
Tenth Embodiment
[0155] An example in which the present invention is applied to a
bumper, which is one of automobile components, will now be
described.
[0156] As shown in FIG. 23, a cylindrical aluminum stay (second
member) 120 is clinched to a closed-cross-section steel bumper beam
(first member) 110 having a partition 111 in the middle. The steel
bumper beam 110 has openings 113 and 113 at opposite sides thereof.
The openings 113 and 113 are separated from each other by the
partition 111. For illustrative purposes, a top plate 114 (see FIG.
26A) of the steel bumper beam 110 is shown in a removed state in
FIG. 23. As shown in FIG. 24A, for the implementation, a bulging
jig 150 including a round-rod-shaped rubber piece 130, a tabular
steel plate 131, and a narrow round rod 140 composed of steel is
used. A through-hole 112 into which the narrow round rod 140 is
insertable is provided in the middle of the rubber piece (elastic
body) 130 and the tabular plate 131. One end of the round rod 140
is provided with a brim 141 for preventing the rubber piece 130
from falling out. The rubber piece 130 is split into two, one of
which is provided with a countersunk hole 132 to which the brim 141
of the round rod 140 is fittable. The tabular plate 131 is placed
on the rubber piece 130 with the countersunk hole 132 facing
downward, the other rubber piece 130 is placed thereon, and the
round rod 140 is subsequently inserted from below. The plate 131
has a circular shape with an outer diameter of .PHI.83.5 mm and a
thickness of 10 mm. The rubber pieces 130 used are composed of
urethane rubber and have a circular shape with an outer diameter of
.PHI.83.5 mm, a length of 50 mm, and a Shore A hardness of 90.
[0157] FIG. 24B illustrates a state where the aluminum stay 120 is
fitted in the hole (hole) 112 (see FIG. 23) provided in the steel
bumper beam 110, and the aforementioned bulging jig 150 is inserted
in the aluminum stay 120. As shown in FIG. 23, the steel bumper
beam 110 is processed into a closed-cross-sectional shape having a
partition 111 in the middle by roll-forming a 1470-MPa-class
cold-rolled steel plate having a thickness of 1.4 mm and has a
circular hole 112 having an outer diameter of .PHI.90.2 mm formed
in the joining section with the aluminum stay 120. In this case,
the partition 111 in the middle is partially removed. The aluminum
stay 120 is formed of a circular pipe composed of an aluminum alloy
A6063 and having a thickness of 3 mm, an outer diameter of .PHI.90
mm, and a length of 150 mm.
[0158] Next, a clinching process shown in FIGS. 25A and 25B will be
described. FIG. 25A illustrates a state where the steel bumper beam
110, the aluminum stay 120, and the bulging jig 150 are set on a
lower mold 152, and a presser jig 151 is disposed thereon. This
state is set in the pressing device 40 (see FIGS. 2A to 2D), and a
slide having the presser jig 151 set thereon is lowered so as to
apply a compressive force to the rubber pieces 130. In this case,
pressure along the axis L of the aluminum pipe 20 is not applied,
as shown in FIGS. 9A and 9B.
[0159] FIG. 25B illustrates a state where the slide is at the
bottom dead center. The rubber pieces 130 are compressed by the
presser jig 151 so as to expand in the horizontal direction,
thereby bulge-forming the aluminum stay 120. Because the tabular
plate 131 is inserted, the joint surface of the steel bumper beam
110 does not receive an excessive force so that undesired
deformation is suppressed, whereby a clinching process with high
fit accuracy is completed.
[0160] FIGS. 26A and 26B illustrate the steel bumper beam 110 and
the aluminum stay 120 upon completion of the clinching process.
FIG. 26A is a cross-sectional view of the steel bumper beam 110 and
the aluminum stay 120 in a clinched state, and FIG. 26B is a
cross-sectional view taken along line XXVI-XXVI. This embodiment is
characterized in that the joint strength is high since clinching
can be achieved at the middle partition 111 in addition to
clinching at the hole 112 provided in the steel bumper beam 110 due
to expansion of the aluminum stay 120 caused by the rubber pieces
130 shown in FIG. 26B.
Eleventh Embodiment
[0161] A joining method according to this embodiment shown in FIGS.
27A to 27F is similar to that in the fifth embodiment in FIGS. 9A
and 9B except that the aluminum pipe 20 has a partition wall 23
therein and a plurality of rubber pieces 30 are inserted in the
aluminum pipe 20. Therefore, parts identical to those in the
configuration shown in FIGS. 9A and 9B will be given the same
reference signs, and descriptions thereof will be omitted.
[0162] As shown in FIG. 27A, the aluminum pipe 20 according to this
embodiment has outer walls 24 extending along the axis L and having
a rectangular shape in cross section and the partition wall 23
provided inside the outer walls 24. The space inside the aluminum
pipe 20 is divided into four spaces by the partition wall 23 having
a cross shape in plan view. By providing the partition wall 23 in
this manner, the strength of the aluminum pipe 20 can be increased.
The cross-sectional shape is not limited to the rectangular shape
and may be a freely-chosen shape.
[0163] As shown in FIGS. 27B and 27C, the indenter 43 according to
this embodiment is provided with a cutout 43c in conformity to the
shape of the partition wall 23. By providing the cutout 43c, the
clinching process can be completed without interference with the
aluminum pipe 20 even when the rubber pieces 30 are pressed.
[0164] Accordingly, because the clinching process is performed by
using the plurality of rubber pieces 30 (i.e., four in this
embodiment), concentration of stress caused by deformation can be
prevented, so that the load on the steel component 10 and the
aluminum pipe 20 can be reduced.
[0165] The shape of each rubber piece 30 according to this
embodiment is not limited in particular. For example, as shown in
FIG. 27D, the corners of the four inserted rubber pieces 30 may be
round-chamfered so as to reduce the load on the corners of the
aluminum pipe 20, thereby preventing cracking and damaging. As
shown in FIG. 27E, C-chamfering may be performed, similarly to
round-chamfering. As shown in FIG. 27F, although the shape of the
four inserted rubber pieces 30 is columnar, steel L-shaped angles
46 may be disposed along the partition wall 23 within the aluminum
pipe 20. Consequently, the load on the partition wall 23 can be
reduced, thereby suppressing deformation.
Twelfth Embodiment
[0166] A joining method according to this embodiment shown in FIGS.
28A and 28B is similar to that in the fifth embodiment in FIGS. 9A
and 9B except that the steel component 10 and the aluminum pipe 20
are joined together in an inclined state. Therefore, parts
identical to those in the configuration shown in FIGS. 9A and 9B
will be given the same reference signs, and descriptions thereof
will be omitted.
[0167] As shown in FIGS. 28A and 28B, the aluminum pipe 20
according to this embodiment has an end surface 25 inclined
relative to the axis L. The steel component 10 is bent and is
placed on an inclined surface 42c. The aluminum pipe 20 is placed
on the inclined surface 42c in a state where the inclined end
surface 25 is in contact therewith, and is clinched to the steel
component 10. Therefore, the steel component 10 and the aluminum
pipe 20 are clinched together in an inclined state. Opposite end
surfaces 30b and 30c of the rubber piece 30 according to this
embodiment are formed and disposed parallel to the inclined end
surface 25 of the aluminum pipe 20. A pressing surface 43d of the
indenter 43 is also formed parallel to the end surfaces 30b and 30c
of the rubber piece 30.
[0168] Accordingly, this method can be used for clinching the steel
component 10 and the aluminum pipe 20 together in an inclined
state, which is often seen from a practical standpoint.
Specifically, the opposite end surfaces 30b and 30c of the rubber
piece 30 are given the same angle as the joining angle, so that the
rubber piece 30 expands uniformly, whereby the aluminum pipe 20 can
be expanded uniformly.
Thirteenth Embodiment
[0169] A joining method according to this embodiment shown in FIGS.
29A to 29D is similar to that in the fifth embodiment in FIGS. 9A
and 9B except that the steel component 10 is joined in a state
where deformation thereof is restrained by a fixation jig 47.
Therefore, parts identical to those in the configuration shown in
FIGS. 9A and 9B will be given the same reference signs, and
descriptions thereof will be omitted.
[0170] As shown in FIGS. 29A and 29B, the steel component 10
according to this embodiment has a bottom wall 11 and an upright
wall 18 extending along the axis L from the bottom wall 11. The
cross-sectional shape of the aluminum pipe 20 before the clinching
process is not particularly limited and may be circular (see the
dashed line in FIG. 29A) or rectangular (see the dashed line in
FIG. 29B). The fixation jig 47 for suppressing deformation is
provided at the outer side of the steel component 10. The fixation
jig 47 is disposed along the upright wall 18 and is fixed from the
directions of the arrows in the drawings so as not to move outward.
Although the fixation jig 47 used in this embodiment is tabular,
the shape of the fixation jig 47 is not limited to this shape and
may alternatively be a freely-chosen shape that can suppress
deformation.
[0171] As shown in FIGS. 29C to 29E, in a case where the fixation
jig 47 is not provided, the steel component 10 may deform in a
warping manner when clinching is performed (see FIG. 29D). However,
with the fixation jig 47, deformation of the steel component 10 is
restrained, so that deformation, such as warping, of the steel
component 10 caused by expansion of the aluminum pipe 20 can be
suppressed (see FIG. 29E).
REFERENCE SIGNS LIST
[0172] 10 steel component (first member) [0173] 11 bottom wall
(first section) [0174] 12, 13 side wall [0175] 12a, 13a bead
section [0176] 14 upper wall (second section) [0177] 15 hole (first
hole) [0178] 15a shoulder section [0179] 15b corner section [0180]
15c straight side section [0181] 17 hole (second hole) [0182] 18
upright wall [0183] 20 aluminum pipe (second member) [0184] 21 edge
[0185] 22 expanding region [0186] 23 partition wall [0187] 24 outer
wall [0188] 25 end surface [0189] 30 rubber piece (elastic body)
[0190] 30a high-hardness section [0191] 30b, 30c end surface [0192]
31 plate [0193] 32 fluid sealing member [0194] 40 pressing device
[0195] 41 outer-frame mold [0196] 42 strike plate [0197] 42a
protrusion [0198] 42b brim [0199] 42c inclined surface [0200] 43
indenter [0201] 43a protrusion [0202] 43b brim [0203] 43c cutout
[0204] 43d pressing surface [0205] 44 outer-frame mold [0206] 44a
large-diameter section [0207] 45 outer frame [0208] 46 L-shaped
angle [0209] 47 fixation jig [0210] 50 resinous tube component
[0211] 110 steel bumper beam (first member) [0212] 111 partition
[0213] 112 hole (hole) [0214] 113 opening [0215] 114 top plate
[0216] 120 aluminum stay (second member) [0217] 130 rubber piece
(elastic body) [0218] 131 plate [0219] 132 countersunk hole [0220]
140 round rod [0221] 141 brim [0222] 150 bulging jig [0223] 151
presser jig [0224] 152 lower mold
* * * * *