U.S. patent application number 11/236354 was filed with the patent office on 2006-03-30 for structure of joining resin molded bodies.
This patent application is currently assigned to G P Daikyo Corporation. Invention is credited to Satoshi Enokida, Koichi Fujikawa.
Application Number | 20060068161 11/236354 |
Document ID | / |
Family ID | 36062392 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060068161 |
Kind Code |
A1 |
Enokida; Satoshi ; et
al. |
March 30, 2006 |
Structure of joining resin molded bodies
Abstract
A reliable and superior joining strength in entire joining parts
of resin molded bodies including tilting portions is obtained by
devising a shape and a size of each protrusion for welding provided
in the joining parts of the resin molded bodies. In a structure of
joining resin molded bodies according to the present invention,
upper and lower half bodies 10 and 20 are joined with each other by
means of a vibration welding method while the upper and lower half
bodies 10 and 20 are being pressurized in a state in which joining
parts thereof are butted into each other in a substantially entire
area of the joining parts. The joining parts of the respective half
bodies have vertical portions 11 and 13 and vertical portions 21
and 23 respectively vertical to a pressurizing direction and
tilting portions 12 and 22 tilting relative to the pressurizing
direction, and protrusions for welding 11E to 13E or 21E to 23E are
provided in at least the joining part of one of the half bodies.
Further, referring to a butting area of the protrusions in a butted
state, the butting area in the vertical portions is set to be
narrower than the butting area in the tilting portions.
Inventors: |
Enokida; Satoshi;
(Higashihiroshima-shi, JP) ; Fujikawa; Koichi;
(Higashihiroshima-shi, JP) |
Correspondence
Address: |
HAMRE, SCHUMANN, MUELLER & LARSON, P.C.
P.O. BOX 2902-0902
MINNEAPOLIS
MN
55402
US
|
Assignee: |
G P Daikyo Corporation
Higashihiroshima-shi
JP
|
Family ID: |
36062392 |
Appl. No.: |
11/236354 |
Filed: |
September 27, 2005 |
Current U.S.
Class: |
428/119 ;
428/60 |
Current CPC
Class: |
B29C 66/71 20130101;
B29C 66/1122 20130101; B29C 66/30223 20130101; B29K 2077/00
20130101; B29C 66/71 20130101; B29C 66/45 20130101; Y10T 428/195
20150115; B29C 66/8322 20130101; Y10T 428/24174 20150115; B29C
65/06 20130101; B29C 66/545 20130101 |
Class at
Publication: |
428/119 ;
428/060 |
International
Class: |
B32B 7/00 20060101
B32B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2004 |
JP |
2004-281761 |
Claims
1. A joining structure for joining a pair of resin molded bodies by
means of a vibration welding method while applying a pressure to
the pair of resin molded bodies in a state in which joining parts
of the pair of resin molded bodies are butted into each other
across a substantially entire area thereof, wherein: the joining
parts of the pair of resin molded bodies have vertical portions
vertical to a direction in which the pressure is applied and
tilting portions tilting relative to the pressurizing direction;
the protrusions for welding are provided in at least the joining
part of one of the pair of resin molded parts; and a butting area
of the protrusions in the vertical portions is set to be narrower
than a butting area thereof in the tilting portions in a state in
which the protrusions are butted.
2. A joining structure for joining a pair of resin molded bodies
according to claim 1, wherein: the forgoing constitution is
preferably adapted to increase the butting area of the protrusions
in the vertical portions toward a base of each protrusion.
3. A joining structure for joining a pair of resin molded bodies
according to claim 1, wherein: the protrusions in the pressurizing
direction more preferably have a substantially rectangular shape in
section in the tilting portions, substantially a triangular shape
in section in the vertical portions and substantially a trapezoidal
shape in section between the vertical portions and the tilting
portions.
4. A joining structure for joining a pair of resin molded bodies
according to claim 1, wherein: referring to a sectional area of
welding margins of the protrusions in a direction orthogonal to a
butting surface, the sectional area in the tilting portions is more
preferably set to be equal to or more than sectional area in the
vertical portions.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a joining structure of
resin molded bodies by means of a vibration welding method while
applying a pressure to the pair of resin molded bodies in a state
in which joining parts of the pair of resin molded bodies are
butted into each other across a substantially entire area of the
joining parts.
[0003] 2. Description of the Related Art
[0004] Conventionally, as a generally known method of joining a
pair of resin molded bodies is available a so-called vibration
welding method, in which a vibration is applied to the resin molded
bodies in a state in which joining parts of the pair of resin
molded bodies are butted into each other and pressurized so that
the pair of resin molded bodies are joined with each other.
[0005] However, it is a publicly known problem in joining the resin
molded bodies with each other by means of the vibration welding
method that it is quite difficult to obtain a reliable and superior
joining strength across the entire joining parts due to a generally
known difficulty in stably and favorably welding any section of the
joining parts tilting relative to a direction in which the pressure
is applied (tilting portion) in the case in which a shape of the
resin molded bodies are complicated in such manner that the joining
parts include not only a section vertical to the pressurizing
direction (vertical portion) but also the aforementioned tilting
portion.
[0006] In order to solve the foregoing problem, for example,
Unexamined Japanese Patent Publication Nos. 2002-364469 and
2002-364471 disclose a method of welding a resin structure in which
a sufficient increase of a joining strength of a tilting line
section on a joining line is pursued in joining the resin molded
bodies having a complicated shape.
SUMMARY OF THE INVENTION
[0007] The foregoing conventional technology proposed the following
two methods; a method in which welding margins of the tilting
portions in the pressurizing direction is set to be larger than any
other welding margin in the same direction and the tilting portions
are welded prior to any other part; and a method in which a
pressurizing force is changed in a step of welding the tilting
portions and in a step of welding the entire joining parts and the
pressurizing force of the latter step is set to be larger than that
of the former step.
[0008] Yet, it is actually very difficult to attain a reliable and
superior joining strength across the entire joining parts in either
of the methods.
[0009] Therefore, a main object of the present invention is to
provide a structure of joining resin molded bodies capable of
realizing a reliable and superior joining strength across entire
joining parts including tilting parts by devising a shape and a
size of each protrusion for welding provided in the joining parts
of the resin molded bodies.
[0010] In order to achieve the foregoing object, a structure of
joining resin molded bodies according to the present invention is a
joining structure for joining a pair of resin molded bodies by
means of a vibration welding method while applying a pressure to
the pair of resin molded bodies in a state in which joining parts
of the pair of resin molded bodies are butted into each other
across a substantially entire area thereof, wherein the joining
parts of the pair of resin molded bodies have vertical portions
vertical to a direction in which the pressure is applied and
tilting portions tilting relative to the pressurizing direction,
the protrusions for welding are provided in at least the joining
part of one of the pair of resin molded parts, and a butting area
of the protrusions in the vertical portions is set to be narrower
than a butting area thereof in the tilting portions in a state in
which the protrusions are butted.
[0011] The forgoing constitution is preferably adapted to increase
the butting area of the protrusions in the vertical portions toward
a base of each protrusion.
[0012] The protrusions in the pressurizing direction more
preferably have a substantially rectangular shape in section in the
tilting portions, substantially a triangular shape in section in
the vertical portions and substantially a trapezoidal shape in
section between the vertical portions and the tilting portions.
[0013] Referring to a sectional area of welding margins of the
protrusions in a direction orthogonal to a butting surface, the
sectional area in the tilting portions is more preferably set to be
equal to or more than sectional area in the vertical portions.
[0014] In the structure of joining the resin molded bodies
according to the present invention, the butting area of the
protrusions for welding in the tilting portions in the state in
which the protrusions are butted is set to be larger than the
butting area thereof in the vertical portions in the same state.
Therefore, when the vibration welding is carried out while the
pressure is applied to the resin molded bodies in the butted state,
a welding area in the tilting portions is larger than a welding
area in the vertical portions at least in an initial stage of the
welding. As a result, the joining strength in the tilting portion,
in which it is generally difficult to obtain a reliable and
superior joining strength in comparison to the vertical portion,
can be enhanced, and the reliable and superior joining strength can
be thereby realized across the entire joining parts.
[0015] In the foregoing constitution, the butting area of the
protrusions in the vertical portions is preferably set to be larger
toward the base of each protrusion. As a result, the welding area
in the vertical portions can be increased as the welding advances
without necessarily changing the pressurizing force applied to the
resin molded bodies though the welding area is relatively small in
the initial stage of the welding. Thereby, a required joining
strength in the vertical portions can be assured.
[0016] Further, the protrusions in the pressurizing direction more
preferably have the substantially rectangular shape in section in
the tilting portions so that the welding area is substantially
constant regardless of the advancement of the welding. As a result,
the reliable joining strength can be obtained. In contrast, the
protrusions in the pressurizing direction preferably have the
substantially triangular shape in section in the vertical
directions so that the welding area can be increased as the welding
advances. Therefore, the welding area in the vertical portions can
be increased as the welding advances without necessarily changing
the pressurizing force though the welding area in the initial stage
of the welding is relatively small. As a result, the required
joining strength in the vertical portions can be assured. Further,
the protrusions in the pressurizing direction preferably have the
substantially trapezoidal shape in section between the vertical
portions and the tilting portions so that a drastic change of the
welding area in the joining region from the tilting portions
through the vertical portions can be alleviated. As a result, the
reliable and superior joining strength can be realized in the
entire joining parts.
[0017] Further, the sectional area of the welding margins of the
protrusions in the direction orthogonal to the butting surface in
the tilting portions is more preferably set to be equal to or more
than the sectional area thereof in the same direction in the
vertical portions so that a welding amount in the tilting portions
can be equal to or more than a welding amount in the vertical
portions in the direction orthogonal to the butting surface.
Thereby, the joining strength in the tilting portions, in which it
is generally difficult to obtain the reliable and superior joining
strength in comparison to the vertical portion, can be enhanced. As
a result, the reliable joining strength can be obtained across the
entire joining parts in the direction orthogonal to the butting
surface.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a front view of upper and lower half bodies
according to an embodiment of the present invention.
[0019] FIG. 2 is a plan view of the lower half body.
[0020] FIG. 3 is a sectional view of a protrusion for welding in
the upper half body in a pressurizing direction.
[0021] FIG. 4 is a sectional view of a protrusion for welding in a
tilting portion of the upper half body in the pressurizing
direction.
[0022] FIG. 5 is a sectional view of a protrusion for welding in a
vertical portion of the upper half body in the pressurizing
direction.
[0023] FIG. 6 is a sectional view of a protrusion for welding
between the tilting portion and the vertical portion of the upper
half body in the pressurizing direction.
[0024] FIG. 7 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0025] FIG. 8 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0026] FIG. 9 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0027] FIG. 10 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0028] FIG. 11 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0029] FIG. 12 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0030] FIG. 13 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0031] FIG. 14 is a sectional view of a modification example of the
protrusion for welding in the vertical portion of the upper half
body in the pressurizing direction.
[0032] FIG. 15 is an illustration of an example of a welding margin
of the protrusion for welding in the vertical portion.
[0033] FIG. 16 is a graph showing a variation of a welding area in
a direction in parallel with a butting surface in a
triangular-shape welding margin in accordance with an advancement
of the welding.
[0034] FIG. 17 is a graph showing a variation of a contact pressure
and a variation of a welding sectional area in a direction
orthogonal to the butting surface in accordance with the
advancement of the welding in the case of the triangular-shape
welding margin.
[0035] FIG. 18 is a graph showing a variation of a welding area in
the direction parallel with the butting surface in accordance with
the advancement of the welding in the case of a bell-shape welding
margin.
[0036] FIG. 19 is a graph showing a variation of a contact pressure
and a variation of a welding sectional area in the direction
orthogonal to the butting surface in accordance with the
advancement of the welding in the case of the bell-shape welding
margin.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] Hereinafter, a preferred embodiment of the present invention
is described referring to the drawings.
[0038] FIG. 1 is a front view of an upper half body and a lower
half body constituting a pair of resin molded bodies according to
the present embodiment. FIG. 2 is a plan view of the lower half
body.
[0039] As shown in FIG. 1, an upper half body 10 and a lower half
body 20 are respectively formed into a saddle shape in front view
by left and right lower sides 11 and 21, upper sides 13 and 23
substantially in parallel with the lower sides 11 and 21, and slant
sides 12 and 22 connecting the upper sides 13 and 23 and the lower
sides 11 and 21. When the half bodies 10 and 20 are vertically
butted into each other and thereby joined with each other, an
integrated resin product comprising a hollow part is formed. In
other words, a lower edge of the upper half body 10 and an upper
edge of the lower half body 20 respectively constitute joining
parts thereof.
[0040] The upper half body 10 and the lower half body 20 are
respectively formed from, for example, polyamide resin in which
glass reinforced fibers are combined.
[0041] When the upper and lower half bodies 10 and 20 are joined
with each other, the bodies 10 and 20 are combined with each other
in the vertical direction shown in FIG. 1 so that the substantially
entire joining parts thereof are butted into each other. Then, in
the state in which they are butted into each other, a pressure is
applied to both of the half bodies 10 and 20 in a direction
indicated by an arrow F shown in FIG. 1, while a vibration of a
predetermined vibration number and amplitude is applied thereto at
the same time in a direction indicated by a reciprocating arrow K
shown in FIG. 2. As a result, the half bodies 10 and 20 are joined
with each other by means of the vibration welding method.
[0042] In the aforementioned butted state, the lower sides 11 and
21 and the upper sides 13 and 23 of the respective half bodies 10
and 20 are substantially vertical to the pressurizing direction
(see arrow F direction), while the slant sides 12 and 22 are tilted
relative to the pressurizing direction.
[0043] Joining parts 11s and 21s in the lower sides 11 and 21 and
joining parts 13s and 23s in the upper sides 13 and 23 of the
respective half bodies 10 and 20 correspond to the "vertical
portions" recited in the claims of the present invention, while
joining parts 12s and 22s in the slant sides 12 and 22 thereof
correspond to the "tilting portions" recited therein.
[0044] In the joining parts of the half bodies 10 and 20,
protrusions for welding 11E, 12E, 13E, 21E, 22E and 23E are
provided in response to the lower sides 11 and 21, the slant sides
12 and 22 and the upper sides 13 and 23. When the half bodies 10
and 20 are butted into each other, the protrusions for welding 11E,
12E and 13E of the upper half body 10 and the protrusions for
welding 21E, 22E and 23E of the lower half body 20 are respectively
butted into each other.
[0045] The protrusions for welding as described above are not
necessarily provided in both of the upper and lower half bodies 10
and 20, but may be provided in one of them.
[0046] Referring to a butting area in the state in which the
protrusions for welding 11E, 12E and 13E and the protrusions for
welding 21E, 22E and 23E are respectively butted into each other in
the present embodiment, the butting area in the vertical portions
vertical to the pressurizing direction (the joining parts 11s and
21s of the lower sides 11 and 21 and the joining parts 13s and 23s
of the upper sides 13 and 23) is set to be narrower than the
butting area in the tilting portions tilted relative to the
pressurizing direction (the joining parts 12s and 22s of the slant
sides 12 and 22).
[0047] Next, s shape of the protrusions for welding in a section
along the pressurizing direction (that is, sectional shape in the
pressurizing direction) is described.
[0048] In the present embodiment, the protrusions for welding 1E,
12E and 13E in the vertical portions 11s and 13s and the tilting
portion 12s of the upper half body 10 have a same shape in section
in the pressurizing direction. Referring to the protrusion for
welding 13E in the joining part 13s of the upper side 13, for
example, the protrusion 13E including a welding margin 13w has a
substantially rectangular shape in section as shown in FIG. 3.
[0049] Referring to the lower half body 20, the protrusions for
welding 21E and 23E in the vertical portions 21s and 23s and the
protrusion for welding 22E and the tilting portion 22s are arranged
to have different sectional shapes in the pressurizing
direction.
[0050] More specifically, the protrusion for welding 22E in the
tilting portion 22s including a welding margin 22w has the
substantially rectangular shape in section in the pressurizing
direction as shown in FIG. 4. Referring to the sectional shapes of
the protrusions for welding 21E and 23E in the vertical portions
21s and 23s in the pressurizing direction, the protrusion for
welding 23E in the joining part 23s of the upper side 23, for
example, has the substantially rectangular shape from a base
through an intermediate position thereof and a substantially
triangular shape in section at an edge side thereof (that is, a
welding margin 23w) as shown in FIG. 5.
[0051] The protrusion for welding 24E between the vertical portions
21s and 23s and the tilting portion 22s has the substantially
rectangular shape in section in the pressurizing direction from a
base through an intermediate position thereof and a substantially
trapezoidal shape at an edge side thereof (that is, a welding
margin 24w) as shown in FIG. 6.
[0052] Because the protrusions for welding 11E, 12E and 13E of the
upper half body 10 and the protrusions for welding 21E, 22E and 23E
of the lower half body 20 are arranged to have the foregoing shapes
in section in the pressurizing direction, the butting area in the
tilting portions 12s and 22s is larger than the butting area in the
vertical portions 11s and 21s and in the vertical portions 13s and
23s in the state in which the protrusions for welding are
butted.
[0053] Therefore, when the vibration welding is carried out while
the half bodies 10 and 20 are pressurized in the butted state, a
welding area of the tilting portions 12s and 22s is larger than
welding area of the vertical portions 11s and 21s and the vertical
portions 13s and 23s at least in an initial stage of the welding
(in the present embodiment, until the welding in the entire welding
margins is completed). Thereby, a joining strength can be enhanced
in the tilting portions 12s and 22s, in which it is generally
difficult to obtain a reliable and superior joining strength in
comparison to the vertical portions 11s and 21s, and the vertical
portions 13s and 23s, and a reliable and superior joining strength
can be realized across the entire joining parts.
[0054] In particular, because the protrusions for welding 21E and
23E of the vertical portions 21s and 23s have the substantially
rectangular shape in section the pressurizing direction from the
base through the intermediate position thereof and the
substantially triangular shape in section at the edge side thereof
(that is, the welding margins 21w and 23w), the butting area of the
protrusions for welding 21E and 23E in the vertical portions 21s
and 23s is increased toward the bases of the protrusions 21E and
23E until the welding in the welding margins 21w and 23w is
completed.
[0055] Therefore, the welding area in the vertical portions 21s and
23s can be increased as the welding advances without necessarily
changing the pressurizing force with respect to the half bodies 10
and 20 though the welding area is relatively small in the initial
stage of the welding. As a result, a required joining strength in
the vertical portions 11s and 21s and the vertical portions 13s and
23s can be assured.
[0056] Because the protrusions for welding 21E, 22E and 23E of the
lower half body 20 are arranged to have the substantially
rectangular shape in section the pressurizing direction in the
tilting portion 22s, the welding area can be substantially constant
regardless of the advancement of the welding, which realizes the
reliable joining strength. In contrast to that, the welding margins
in the vertical portions 21s and 23s have the substantially
triangular shape so that the welding area can be increased as the
welding advances. As a result, the welding area can be increased as
the welding advances without necessarily changing the pressurizing
force though the welding area is relatively small in the initial
stage of the welding, which leads to the assurance of the required
joining strength. Further, the substantially trapezoidal shape is
arranged between the vertical portions 21s and 23s and the tilting
portion 22s so that a drastic change of the welding area can be
alleviated in the joining region from the tilting portion 22s
through the vertical portions 21s and 23s. As a result, the
reliable and superior joining strength across the entire joining
parts can be realized.
[0057] FIGS. 7 through 14 respectively show various examples of
modifications of the sectional shape of the protrusion for welding
in the pressurizing direction provided in the lower half body 20.
In protrusions for welding E7 and E18 shown in FIGS. 7 and 8, the
rectangular shape and the triangular shape are combined. The
protrusions for welding E9 and E 10 shown in FIGS. 9 and 10 is a
modification in which a curved line is applied to the triangular
shape. A protrusion for welding E11 shown in FIG. 11 has a bell
shape, and a protrusion for welding E12 shown in FIG. 12 is a
modification of the bell-shaped E11. The protrusions for welding
E13 and E 14 shown in FIGS. 13 and 14 is a modification in which a
recessed portion is provided in a central part in section.
[0058] According to the present embodiment, referring to a
sectional area of welding margins of the protrusions for welding
21E, 22E and 23E in the lower half body 20 in a direction
orthogonal to a butting surface, the sectional area in the tilting
portion 22s is set to be equal to or more than the sectional area
in the vertical portions 21s and 23s.
[0059] When the sectional areas are set as described, a welding
amount in the tilting portion 22s can be equal to or more than a
welding amount in the vertical portions 21s and 23s in the
direction orthogonal to the butting surface so that the joining
strength in the tilting portions 21s and 23s, in which it is
generally difficult to obtain the reliable and superior joining
strength in comparison to the vertical portion 22s, can be
enhanced. As a result, the reliable and superior joining strength
can be attained in the entire joining parts in a direction
orthogonal to a butting surface.
[0060] In particular, the sectional area in the tilting portion 22s
is arranged to be substantially equal to the sectional area in the
vertical portions 21s and 23s so as to minimize a difference
between the respective welding amounts in the tilting portion 22s
and the vertical portions 21s and 23s. As a result, the joining
strength can be more reliable in the entire joining parts.
[0061] A simulation for the structure of joining the resin molded
bodies constituted as described was carried out, which examined a
variation of the welding areas in the vertical portions and the
tilting portions and a variation of the pressurizing force
(so-called contact pressure) in the direction orthogonal to the
butting surface in accordance with the advancement of the
welding.
[0062] Below is given a description of the simulation.
[0063] The simulation was carried out regarding a case in which the
welding margin of the protrusion for welding in the tilting portion
has the rectangular shape in section in the pressurizing direction
(see FIG. 4) as in the conventional case, and the welding margin of
the protrusion for welding in the vertical portion has the
triangular shape in section in the pressurizing direction (see FIG.
5) and the bell shape (see FIG. 11), and the conventional joining
structure in which the welding margins of the protrusions for
welding in the vertical and tilting portions both have the
rectangular shape in section in the pressurizing direction was used
for comparison.
[0064] FIG. 15 shows sectional shapes and dimensions in the
pressurizing direction in the examples of the welding margin of the
protrusion for welding in the vertical portion, which were used in
the present simulation. A width of the welding margin is 4.0 mm and
a height thereof is 2 mm at maximum in the both examples. An entire
sectional area thereof is 4 mm.sup.2 in the case of the triangular
shape and 4.28 mm.sup.2 in the case of the bell shape. A tilting
angle of the tilting portion relative to the pressurizing direction
is 45 degrees.
[0065] Further, a width of the welding margin in the example of the
welding margin of the protrusion for welding in the tilting portion
(rectangular shape) is constantly 4.0 mm, and the same values are
employed in the vertical and tilting portions in the conventional
structure for comparison.
[0066] All of the sectional shapes in the pressurizing direction in
an opposite welding margin of the joining parts to be butted into
the aforementioned welding margin (in both vertical and tilting
portions) are rectangular.
[0067] In the foregoing joining structure set as above, the welding
areas in the vertical portion and the tilting portion and the
pressurizing force (so-called contact pressure) in the direction
orthogonal to the butting surface in accordance with the
advancement of the welding were examined in the case of
vibration-weld the welding margins in the foregoing examples by
applying a pressure thereto by means of a hydraulic or pneumatic
pressurizing device and applying a predetermined vibration in the
state in which the welding margins were butted into each other.
[0068] In this case, a predetermined pressurizing force of the
pressurizing device was set to, for example, 2 MPa, and the welding
area and the contact pressure were calculated in each advancement
of the welding (sinking) per 0.25 mm. Further, the sectional area
of the welding part in the direction orthogonal to the butting
surface (that is, welding sectional area) in the respective
examples of the welding margin was also calculated.
[0069] Tables 1 and 2 show a calculation result of the example in
which the welding margin in the vertical portion has the triangular
shape in section in the pressurizing direction (see FIG. 5). FIGS.
16 and 17 show graphs respectively corresponding to the Tables 1
and 2.
[0070] The Table 1 and FIG. 16 show a variation of the welding area
in a direction in parallel with the butting surface in the case of
the triangular shape (so-called plane parallel direction) in
accordance with the advancement of the welding. TABLE-US-00001
TABLE 1 Welding area in plane parallel direction (mm.sup.2) Tilting
portion Vertical portion Sinking amount Welding length (mm) 400
Welding length (mm) 400 (mm) Welding width (mm) Welding area
Welding width (mm) Welding area Total welding area 0.00 4 1600 0.00
0.0 1600.0 0.25 4 1600 0.50 200.0 1800.0 0.50 4 1600 1.00 400.0
2000.0 0.75 4 1600 1.50 600.0 2200.0 1.00 4 1600 2.00 800.0 2400.0
1.25 4 1600 2.50 1000.0 2600.0 1.50 4 1600 3.00 1200.0 2800.0 1.75
4 1600 3.50 1400.0 3000.0 2.00 4 1600 4.00 1600.0 3200.0
[0071] The Table 2 and FIG. 17 show a variation of the contact
pressure and a variation of the welding area in the direction
orthogonal to the butting surface (so-called plane vertical
direction) in accordance with the advancement of the welding in the
case of the triangular shape. TABLE-US-00002 TABLE 2 Present
embodiment: welding Present embodiment: sectional area in plane
vertical Comparative example: contact contact pressure (Mpa)
direction (mm.sup.2) pressure (Mpa) Sinking amount Tilting Vertical
Tilting Vertical Tilting Vertical (mm) portion portion portion
portion portion portion 0.00 2.83 4.00 0 0.00 1.41 2.00 0.25 2.51
3.56 1 0.06 1.41 2.00 0.50 2.26 3.20 2 0.25 1.41 2.00 0.75 2.06
2.91 3 0.56 1.41 2.00 1.00 1.89 2.67 4 1.00 1.41 2.00 1.25 1.74
2.46 5 1.56 1.41 2.00 1.50 1.62 2.29 6 2.25 1.41 2.00 1.75 1.51
2.13 7 3.06 1.41 2.00 2.00 1.41 2.00 8 4.00 1.41 2.00
[0072] In FIG. 16, a straight line L1k denotes the welding area in
the tilting portion in the plane parallel direction, and L1s
denotes the welding area in the vertical portion in the plane
parallel direction. As is clear from the Table 1 and FIG. 16, the
welding area in the direction in parallel with the butting surface
(plane parallel direction) is constant in the tilting portion. On
the contrary, the welding area in the vertical portion linearly
increases in accordance with the advancement of the welding (that
is, increase of the sinking amount), and consequently equal to the
welding area in the tilting portion when the welding in the entire
height of the welding margin is completed.
[0073] In FIG. 17, a straight line L2k and a curved line L2s
respectively denote the welding sectional areas in the tilting and
vertical portions in the plane vertical direction, and a curved
line L3k an a curved line L3s respectively denote the contact
pressures in the tilting and vertical portions. A straight line L4k
and a straight line L4s respectively show the contact pressures in
the tilting and vertical portions in the comparative example. In
the comparative example, the protrusion has the rectangular shape
in section in the pressurizing direction in both of the tilting and
vertical portions, which is a general joining structure in the
conventional technology. As is clear from the Table 2 and FIG. 17,
in the present embodiment, the contact pressures in the tilting and
vertical portions is higher than in the case of the comparative
example until the welding in the entire height of the welding
margin is completed. Further, in the present embodiment, the
welding sectional area in the tilting portion in the plane vertical
direction (see the straight line L2k) is larger than the welding
sectional area in the vertical portion in the plane vertical
direction (see the curved line L2s).
[0074] It is learnt from the foregoing description that the joining
strength in the tilting portion, in which it is generally difficult
to obtain the reliable and superior joining strength in comparison
to the vertical portion, can be enhanced.
[0075] Tables 3 and 4 show a calculation result of the example in
which the welding margin in the vertical portion has the bell shape
in section in the pressurizing direction (see FIG. 11). FIGS. 18
and 19 show graphs respectively corresponding to the Tables 3 and
4.
[0076] The Table 3 and FIG. 18 shows the variation of the welding
area in the direction in parallel with the butting surface (plane
parallel direction) in the case of the bell shape in accordance
with an advancement of the welding. TABLE-US-00003 TABLE 3 Welding
area in plane parallel direction (mm.sup.2) Tilting portion
Vertical portion Sinking amount Welding length (mm) 400 Welding
length (mm) 400 (mm) Welding width (mm) Welding area Welding width
(mm) Welding area Total welding area 0.00 4 1600 0.00 0.0 1600.0
0.25 4 1600 0.15 60.0 1660.0 0.50 4 1600 0.35 140.0 1740.0 0.75 4
1600 0.80 320.0 1920.0 1.00 4 1600 2.00 800.0 2400.0 1.25 4 1600
3.20 1280.0 2880.0 1.50 4 1600 4.00 1600.0 3200.0 1.75 4 1600 4.00
1600.0 3200.0 2.00 4 1600 4.00 1600.0 3200.0
[0077] The Table 4 and FIG. 19 show a variation of the contact
pressure and a variation of the welding area in the direction
orthogonal to the butting surface in the case of the bell shape
(plane vertical direction) in accordance with an advancement of the
welding. TABLE-US-00004 TABLE 4 Present embodiment: welding Present
embodiment: sectional area in plane vertical Comparative example:
contact contact pressure (Mpa) direction (mm.sup.2) pressure (Mpa)
Sinking amount Tilting Vertical Tilting Vertical Tilting Vertical
(mm) portion portion portion portion portion portion 0.00 2.83 4.00
0 0.00 1.41 2.00 0.25 2.73 3.86 1 0.02 1.41 2.00 0.50 2.60 3.68 2
0.04 1.41 2.00 0.75 2.36 3.33 3 0.18 1.41 2.00 1.00 1.89 2.67 4
0.59 1.41 2.00 1.25 1.57 2.22 5 1.34 1.41 2.00 1.50 1.41 2.00 6
2.28 1.41 2.00 1.75 1.41 2.00 7 3.28 1.41 2.00 2.00 1.41 2.00 8
4.28 1.41 2.00
[0078] In FIG. 18, a straight line L5k denotes the welding area in
the tilting portion in the plane parallel direction, and L5s
denotes the welding area in the vertical portion in the plane
parallel direction. As is clear from the Table 3 and FIG. 18, the
welding are in the direction in parallel with the butting surface
(plane parallel direction) is constant in the tilting portion. In
contrast to that, the welding area in the vertical direction
increases along a certain curved line in response to the
advancement of the welding (that is, the increase of the sinking
amount) and is consequently equal to the welding area in the
tilting portion when the sinking amount reaches 1.5 mm.
[0079] In FIG. 19, a straight line L6k and a curved line L6s
respectively denote the welding areas in the tilting portion and
the vertical portion in the plane vertical direction, and a curved
line L7k and a curved line L7s respectively denote the contact
pressures in the tilting portion and the vertical portion. Further,
a straight line L8k and a straight line L8s respectively denote the
contact pressures in the tilting and vertical portions in the
comparative example. The comparative example is a general joining
structure similar to the conventional joining structure shown in
FIG. 17.
[0080] As is clear from the Table 4 and FIG. 19, in the present
embodiment, the contact pressure in the vertical portion is higher
than the contact pressure in the comparative example until the
welding in the entire height of the welding margin is completed,
and the contact pressure in the tilting portion is larger than the
contact pressure in the comparative example until the sinking
amount reaches 1.5 mm and is thereafter equal to the contact
pressure in the comparative example. Further, in the present
embodiment, the welding sectional area in the tilting portion in
the plane vertical direction (see the straight line L6k) is larger
than the welding sectional area in the vertical portion in the
plane vertical direction (see the curved line L6s).
[0081] It is learnt from the foregoing description that the joining
strength in the tilting portion, in which it is generally difficult
to obtain the reliable and superior joining strength in comparison
to the vertical portion, can be enhanced.
[0082] It is needles to say that the present invention is not
limited to the foregoing embodiment, and can be variously modified
or corrected without departing from the spirit and the scope of the
present invention.
* * * * *