Note: Descriptions are shown in the official language in which they were submitted.
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SPIN WELDING COMPONENT AND SPIN WELDING METHOD
Technical Field
[0001]
The present invention relates to a welding component as a mounting
member used for spin welding that melts and bonds a welding material by
the frictional heat caused by rotation.
Background Art
[0002]
Patent Literature 1 has been known as the prior art with regard to
spin welding. This aims to reduce a so-called "through transfer
phenomenon" that causes a bent or wrinkle on a mounting substrate 6 in the
process of fixing a fixture 2 to the mounting substrate 6 by rotational
welding. In a rotational welding resin member of Patent literature 1 having
a columnar portion and a disk-shaped flange portion integrally provided at
one end of the columnar portion, the wall thickness of the flange portion is
gradually decreased from the center toward the outer circumference.
Citation List
Patent literature
[0003]
PTL 1: JP H04-026297B
Summary
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Technical Problem
[0004]
There is, however, still a room for improvement with regard to the
technique of enhancing the strength of spin welding or more specifically with
regard to good balance between the manufacturing cost of a welding
component and the welding strength. For example, when a mounting
bracket is spin-welded to a base member, the molten material is
concentrated in the center, so that the mounting bracket rises from the base
member. This causes the problems of failing to provide the sufficient
welding strength, the good appearance and the high dimensional accuracy
(as shown in Fig. 3).
[0005]
An object of the invention is thus to provide a spin welding
component that has a simple configuration of a welding surface and provides
enhanced welding strength, good appearance and high dimensional accuracy.
Solution to Problem
[0006]
By taking into account the above object, according to one aspect of the
invention, there is provided a spin welding component comprising a main
body including a resin; and an opening in a concave shape provided at center
of a bottom of the main body. It is preferable that the main body has a
flange portion integrally provided with a shaft portion and that the opening
is formed on the shaft portion. The opening preferably has a circular
bottom face.
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[0007]
The volume of the opening is preferably set according to the amount
of the molten resin of at least the spin welding component. This ratio may
differ, for example, according to the material of the spin welding component.
It is preferable that the ratio of the amount of molten resin to the volume of
opening is basically 1 to 1. The ratio of amount of molten resin: volume of
the opening may be 1: 0.7 to 1.3. It is generally preferable that the volume
of the opening is greater than the amount of the molten resin. The less
volume of the opening, on the contrary, enables the molten resin to be
pressed downward by the spin welding component. For example, when the
volume of the opening is 0.8 relative to the amount of molten resin =1, a
cover may be placed over the molten resin to apply a pressure. This ensures
favorable bonding. The bonding strength may be increased to 1.4 to 1.6
times. This configuration prevents a pressure of more than necessity from
being applied between the spin welding component and the base member.
This accordingly suppresses deterioration of the appearance by the molten
resin or by deformation of the spin welding component and the base member
and ensures the dimensional accuracy.
[0008]
It is preferable that the bottom face of the spin welding component is
welded to the base member via the resin molten by spinning. When the
spin welding component and the base member are made of the same material,
the material may be melted. When the spin welding component and the
base member are made of different materials, these materials may be
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tangled or dissolved. A welding resin material of the same material or a
different material may be provided on the bottom face of the main body.
[0009]
According to another aspect of the invention, there is provided a spin
welding method comprising: rotating the spin welding component of the
above aspect that is placed on a base member to be in close contact with the
base member; melting the spin welding component by frictional heat
between the base member and the spin welding component caused by the
rotating; causing molten resin to be concentrated in a center and flow into
the opening by the rotating such that the spin welding component presses
the molten resin downward; and solidifying the molten resin flowing into the
opening to weld the spin welding component with the base member.
[0010]
The material of the spin welding component and the material of the
base member may be selected adequately. For example, the material of the
spin welding component may be polyester, polyethylene or polypropylene,
and the material of the base member may be kenaf and/or 50% glass and
50% polypropylene.
[0011]
In the spin welding component of the above aspect, the opening may
be formed in a reverse concave sectional shape having an inner ceiling. The
molten resin may be solidified in the state that the molten resin is in
contact
with the inner ceiling or in the state that the molten resin is not in contact
with the inner ceiling.
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[0012]
The bottom preferably has an approximately circular shape, since
this is suitable for spin welding. This is, however, not essential.
[0013]
In the bottom of the spin welding component of the above aspect, the
opening denotes a cavity in a reverse concave sectional shape having an open
bottom face. An inner ceiling may be formed in an upper portion of the
cavity or may not be formed. The opening is formed in, for example, a
circular shape, but may be formed in another shape such as a rectangular
shape or a hexagonal shape.
[0014]
The shaft portion and the flange portion of the main body may be
formed integrally or may be formed separately and subsequently integrated.
Advantageous Effects of Invention
[00151
The spin welding component according to the above aspect of the
invention has enhanced welding strength. The configuration of the spin
welding component prevents a pressure of more than necessity from being
applied between the spin welding component and a welded member such as a
base member. This accordingly suppresses deformation of the spin welding
component and the base member by the molten resin and ensures the good
appearance in the mounted state and the improved dimensional accuracy.
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Brief Description of Drawings
[0016]
Fig. 1(a) is a downward perspective view illustrating a spin welding
component 1 according to Embodiment 1 of the invention; Fig. 1(b) is an
up Ward perspective view illustrating the spin welding component 1 of
Embodiment 1; Fig. 1(c) is a front view illustrating the spin welding
component 1 of Embodiment 1, wherein molten resin 9 is omitted from the
illustration;
Fig. 2 is a schematic sectional view illustrating the state that the
spin welding component 1 of Embodiment 1 is welded to a base member 8;
Fig. 3 is a schematic sectional view illustrating the state that a
conventional spin welding component 11 is welded to a base member 18;
Fig. 4(a) is a downward perspective view illustrating a spin welding
component 101 according to Embodiment 2 of the invention; Fig. 4(b) is an
upward perspective view illustrating the spin welding component 101 of
Embodiment 2; Fig. 4(c) is a front view illustrating the spin welding
component 101 of Embodiment 2, wherein molten resin 109 is omitted from
the illustration;
Figs. 5(a), 5(b) and 5(c) are diagrams illustrating modifications of the
spin welding component 101 of Embodiment 2;
Fig. 6 is a schematic sectional view illustrating the state that the
spin welding component 101 of Embodiment 2 is welded to a base member
108;
Fig. 7(a) is a downward perspective view illustrating a spin welding
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component 201 according to Embodiment 3 of the invention; Fig. 7(b) is an
upward perspective view illustrating the spin welding component 201 of
Embodiment 3; Fig. 7(c) is a front view illustrating the spin welding
component 201 of Embodiment 3, wherein molten resin 209 is omitted from
the illustration;
Fig. 8(a) is a schematic sectional view illustrating the state that a
spin welding component 401 according to Embodiment 4 is mounted on a
base member 408; and Fig. 8(b) is a schematic sectional view illustrating the
state that a spin welding component 501 according to Embodiment 5 is
mounted on a base member 508; and
Fig. 9 is a graph showing a relationship between the recessed area
and the strength in the case where spin welding components as Examples of
the invention are thermally welded to a base member.
Description of Embodiments
[0017]
A spin welding component 1 according to Embodiment 1 of the
invention is described with reference to Figs. 1 and 2. The spin welding
component 1 includes has a main body including a shaft portion 2 formed in
an approximately columnar shape and a flange portion 3 extended outward
from below the shaft portion 2 to be formed in a disk-like shape as shown in
Figs. 1(a) to 1(c). The spin welding component 1 also includes an opening 4
formed by opening the entirety or part of a bottom face of the shaft portion
2.
[0018]
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The configuration of the spin welding component 1 is described more
specifically with reference to Figs. 1(a) to 1(c). The spin welding component
1 is a plastic molded part produced by integrally molding the shaft portion 2
and the flange portion 3. The shaft portion 2 is formed in a cap-like shape
including a cylindrical body 5 in an approximately cylindrical shape and an
upper plate 6 integrally provided on the cylindrical body 5. The flange
portion 3 is a ring-shaped plate member that is extended radially outward
from the circumference of a lower end of the shaft portion 2 as the base.
The opening 4 is formed at the center of a bottom of the cylindrical body 5 to
define an inner cavity of the shaft portion 2 and is recessed upward from a
bottom face of the spin welding component 1. The bottom of the cylindrical
body 5 is connected with the inner circumference of the flange portion 3, and
the cylindrical body 5 is extended upward from the flange portion 3. The
cylindrical body 5 has diameter expanded downward but may have a fixed
diameter. The upper plate 6 has an upper hole 7 formed in its center. This
is, however, not essential but is an example of the product configuration, and
the upper hole 7 may be omitted. The spin welding component 1 may have
an optional configuration suitable for spin welding or an optional
configuration required according to the specification of a final product.
[0019]
Available examples of the material used for the spin welding
component 1 include thermoplastic resins such as polyester, polyethylene,
polypropylene, polystyrene, polyvinyl chloride, acrylic resin,
acrylonitrile -butadiene -styrene resin, polyethylene terephthalate, nylon,
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polyamide, polycarbonate and polyacetal, thermosetting resins such as
phenolic resin, epoxy resin and melamine resin and composite materials
such as glass fiber-reinforced plastic and carbon fiber-reinforced plastic.
[0020]
Available examples of the material for a welded member to which the
spin welding component 1 is mounted include thermoplastic resins such as
polyester, polyethylene, polypropylene, polystyrene, polyvinyl chloride,
acrylic resin, acrylonitrile-butadiene-styrene resin, polyethylene
terephthalate, nylon, polyamide, polycarbonate and polyacetal and
composite materials of these thermoplastic resins with glass fiber, carbon
fiber or kenaf.
[0021]
According to this embodiment, the spin welding component 1 is made
of polypropylene. The flange portion 3 has a diameter of 40 min(1), and the
opening 4 has a diameter of 22 mm(I). A base member 8 as the welded
member is a plate-like member made of a composite material consisting of
50% kenaf and 50% polypropylene.
[0022]
The following describes a method of welding the spin welding
component 1. The spin welding component 1 is fastened above the base
member 8 as the welded member via a jig (not shown) in a spin welding
machine (not shown). On completion of setting the respective component
and member, the spin welding component 1 is moved downward while
rotating at high speed by the spin welding machine (not shown). The spin
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welding component 1 comes into contact with the base member 8 and is
subsequently kept in close contact with the base material 8 under
application of a downward load. When the spin welding component 1
rotates at high speed at a fixed point, the spin welding component 1 and the
base material 8 are melted by the frictional heat. The molten resin is
flowed toward the center of the opening 4 by the rotation and is solidified to
weld the spin welding component 1 to the base member 8 as shown in Fig. 2.
The spin welding component 1 may be used for automobile interior parts and
may also be favorably used for small parts such as various brackets.
[0023]
The following describes the functions and advantageous effects of the
spin welding component 1. In the mounted state of the spin welding
component 1 shown in Fig. 2, the spin welding component 1 is welded to the
base material 8 in areas A on the lower face of the flange 3. This is
compared with a conventional spin welding component 11 without the
opening 4 with reference to Fig. 3.
[0024]
The conventional spin welding component 11 has the similar
configuration and the similar dimensions except the opening 4 and is made
of the similar material. Spin welding of this conventional spin welding
component 11 causes a molten resin 19 concentrated at the center to be
solidified as shown in Fig. 3.
[0025]
The principle of solidifying the molten resin 19 concentrated at the
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center has not been elucidated. The results of a considerable number of
experiments under the above conditions, however, indicate this phenomenon.
Solidification of the molten resin 19 concentrated at the center causes the
spin welding component 11 to be welded only in an area B but not in areas A.
The spin welding component 11 accordingly rises from the base member 18.
This causes a variation in mounting accuracy and a variation in welding
strength and reduces the welding strength. This also causes deterioration
of the appearance.
[0026]
In the case of the spin welding component 1 according to
Embodiment 1 of the invention, on the other hand, the molten resin that is
melted during spin welding is partly flowed into the opening 4, so that the
spin welding component 1 is welded in the areas A, i.e., in the entre bottom
face of the flange portion 3. This provides the higher welding strength than
the conventional spin welding component. This also suppresses a rise of the
member in the welded state and stably provides the desired mounting
accuracy and the desired welding strength.
[00271
A spin welding component 101 according to Embodiment 2 of the
invention is described with reference to Figs. 4 to 6. The like components to
those of Embodiment 1 are expressed by the like numerals to those of
Embodiment 1 in their 100s and are not specifically described. As shown in
Figs. 4(a) to 4(c), like the spin welding component 1, the spin welding
component 101 includes a shaft portion 102 formed in an approximately
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columnar shape, a flange portion 103 extended outward from below the shaft
portion 102 to be formed in a disk-like shape, and an opening 104 formed by
opening part of a bottom face of the flange portion 103. The opening 104 is
formed in a reverse concave sectional shape having a less opening height
than that of the spin welding component 1 and has an inner ceiling 110.
[0028]
The opening 104 of Embodiment 2 has the inner ceiling 110 provided
to close the upper portion inside of the shaft portion 102 and is accordingly
formed as a cavity in an approximately short cylindrical shape having the
reverse concave sectional shape. Some examples of providing the inner
ceiling 110 are shown in Fig. 5. Fig. 5(a) illustrates the inner ceiling 110
that is an inner configuration formed by integrally filling the cavity other
than the opening 104 to be solid, with molding the spin welding component
101. Fig. 5(b) illustrates an inner ceiling 110' provided to part the cavity
in
a shaft portion 102'. Fig. 5(c) illustrates a configuration obtained by
filling
the cavity of a shaft portion 102" in a spin welding component having the
similar configuration to that of the spin welding component 1 of Embodiment
1 with a filling member 111. The filling member 111 may be made of the
same material as or may be made of a different material from the material of
the shaft portion 102". For example, the material may be a fiber composite
material or a porous material to provide the welding strength with the
molten resin.
[00291
The spin welding component 101 is set in a spin welding machine
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=
(not shown) and is spin-welded to a base member 108 (shown in Fig. 6), like
Embodiment 1.
[0030]
The following describes the functions and advantageous effects of the
spin welding component 101. In the mounted state of the spin welding
component 101 shown in Fig. 6, molten resin 109 concentrated in the
opening 104 like Embodiment 1 is trapped by the inner ceiling 110 and is
solidified in the state that the molten resin 109 is in contact with the inner
ceiling 110. The spin welding component 101 is accordingly welded in an
area B as well as in areas A like Embodiment 1.
[0031]
This welds the entire bottom face of the spin welding component 101
and thereby provides the stronger welding than Embodiment 1. Welding
the entire bottom face reduces a variation in welding strength of an actual
product relative to a designed strength. There is accordingly no need to
apply a load of more than necessity for spin welding. This suppresses
deformation and damaged appearance of the spin welding component 101
and the base member 108 and readily ensures the dimensional accuracy.
[0032]
With regard to the spin welding component 101, it is preferable to use
the same type of thermoplastic resin or thermoplastic resin-containing
composite material for the shaft portion 102, the flange portion 103, the
molten resin 109 and the base member 108. Even when different materials
are used, the molten resin 109 comes in close contact with the shaft portion
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102, the flange portion 103 and the base member 108. This enhances the
strength.
[0033]
A spin molding component 201 according to Embodiment 3 of the
invention is described with reference to Fig. 7. The like components to
those of Embodiment 2 are not specifically described. As shown in Figs. 7(a)
to 7(c), the spin molding component 201 is formed in an approximately
cylindrical shape as a whole without a flange portion and includes an
opening 204 formed on its bottom face in a reverse concave sectional shape
with an inner ceiling 210. The spin welding component 201 of Embodiment
3 has the similar functions and advantageous effects to those of Embodiment
2.
[0034]
A spin molding component 401 according to Embodiment 4 of the
invention is described with reference to Fig. 8(a). The like components to
those of Embodiments 1 to 3 are not specifically described. As shown in Fig.
8(a), the spin welding component 401 has a welding resin film 409 in a
circular shape applied between a shaft portion 402 and a bottom face of a
flange portion 403. The welding resin 409 may be applied to cover an
opening 404 or may be applied not to cover the opening 404. The welding
resin 409 as the molten material is applied in advance on the bottom face of
the spin welding component 401, prior to spin welding. The spin welding
component 401 of Embodiment 4 has the similar functions and advantageous
effects to those of Embodiments 1 to 3.
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[00351
It is preferable to use the same type of thermoplastic resin or
thermoplastic resin-containing composite material as that of the spin
welding component 401 for the welding resin 409 as the molten material.
This is, however, not essential and another material may be used.
According to this embodiment, the welding resin 409 is made of a composite
material consisting of 50% kenaf and 50% polypropylene like a base member
408 and is applied on the bottom face of the spin welding component 401.
[0036]
The following describes a method of welding the spin welding
component 401. The spin welding component 401 is fastened above the
base member 408 as the welded member via a jig (not shown) in a spin
welding machine (not shown). On completion of setting the respective
component and member, the spin welding component 401 is moved
downward while rotating at high speed by the spin welding machine (not
shown). The spin welding component 401 comes into contact with the base
member 408 and is subsequently kept in close contact with the base material
408 under application of a downward load. When the spin welding
component 401 rotates at high speed at a fixed point, the welding resin 409 is
melted by the frictional heat. The melted welding resin 409 is flowed into
the opening 404 by the rotation and is solidified to weld the spin welding
component 401 with the base member 408.
[00371
A spin welding component 501 according to Embodiment 5 of the
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invention is described with reference to Fig. 8(b). The like components to
those of Embodiment 4 are not specifically described. This spin welding
component 501 has an opening 504 of reduced volume. The configuration of
Embodiment 5 has the similar functions and advantageous effects to those of
Embodiment 4. Additionally, the limited volume of the opening 504 has the
effect of pressing the molten resin downward during thermal welding.
[0038]
Fig. 9 is a graph showing the relationship of the strength to the
concave area of the opening 4, 104, 204, 404 or 504. The concave area (%)
herein denotes an area ratio in percentage of the area of the bottom face of
the opening 4, 104, 204, 404 or 504 (cavity) to the area of the bottom face of
the spin welding component 1, 101, 201, 401 or 501 (area of the ring shape,
i.e., the bottom area where the molten resin is present). The entire
diameter of the spin welding component 1, 101, 201, 401 or 501 is in the
range of 20 mm to 40 mm. Type A shows configurations with an inner
ceiling, and type B shows configurations without an inner ceiling in the
bottom face. The concave area of 5 to 35% of the welding area is likely to
increase the strength. The welding strength is increased to about 1.5 times
at most.
[0039]
The rotation speed of the spin welding component 1, 101, 201, 401 or
501 may be about 2500 rpm. The rotation speed, however, depends on the
material of the resin and the configuration of the spin welding component.
The rotation speed is accordingly not limited to this numerical value but may
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be selected in an adequate range.
[0040]
The invention is not limited to the above embodiments but various
modifications, changes and additions may be made to the embodiments
without departing from the scope of the invention. Such modifications as
well as their equivalents are also included in the scope of the invention.
Reference Signs List
[0041]
1, 101, 201 spin welding component
2, 102 shaft portion
3,103 flange portion
4, 104 opening
110 inner ceiling
8, 108 base member
9, 109 molten resin
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