JP2000025117A - Vibratory welding method and vibratory welded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To check the development of burrs at welding and improve a joining strength by a method wherein the tip of a joining piece, the width of which is narrower, is provided in advance so as to have a sectional form with a specified number of projecting parts. SOLUTION: When a first member 1 made of synthetic resin and a second member are welded together, the tip of the joining piece 10, the width of which is narrower, is provided in advance so as to have a sectional form with two projecting parts 12. Then, the joining pieces 10 and 20 are pressingly abutted against each other. Under the state just mentioned above, vibration is applied to the first member 1 and the second member 2 so as to develop a frictional heat between the joining pieces 10 and 20. Thus, first of all, the projecting part 12 of the joining piece 10 and the abutting portion of the joining piece 20 start to melt. In this case, by providing the projecting parts 12 in the joining piece 10, a recessed part 19 is formed, resulting in entering the melted resin developing at the early stage of a vibratory welding within the recessed part 19 and checking the development of burrs. In addition, the joining boundary part 50 of the welding part becomes wavy, resulting in increasing an anchoring effect and a joining area and consequently improving a joining strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration welding method and a vibration welded product of a synthetic resin.

[0002]

2. Description of the Related Art In a synthetic resin product, two or more members may be joined to obtain a product shape. As a joining method in this case, a vibration welding method in which a joining member made of a synthetic resin itself is melted by friction heat and joined is widely used. In this vibration welding method, as shown in FIGS. 6A and 6B, a joining piece 910 and a joining piece 920 are provided at a joining portion between a first member 91 and a second member 92, respectively, and these are pressed and contacted. By applying vibration to the joint piece 9
10, 920 are melted by frictional heat and welded.

[0003]

However, the conventional vibration welding method has the following problems. That is, FIG.
As shown in (b), when the joining pieces 910 and 920 are melted under pressure, the viscosity of the melted portion is greatly reduced. Therefore, the melted joint pieces 910 and 920 largely protrude toward the narrow protruding piece 910, as if the water droplets bounce off the water surface. The raised portions remain as large burrs 99 due to cooling and solidification. As shown in FIG. 6B, the shape of the burr may extend upward on both the left and right sides, and as shown in FIG. 7, one or both burrs 99 may extend in the lateral direction.

Therefore, the vibration welded product joined by the conventional vibration welding method has a problem that the appearance is greatly deteriorated due to the generation of the burrs 99. On the other hand, on the other hand, it has been required to further improve the joining strength of the vibration welded portion.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a vibration welding method and a vibration welded product capable of suppressing the occurrence of burrs during welding and improving the bonding strength. Is what you do.

[0006]

According to a first aspect of the present invention, there is provided a method for welding a first member and a second member made of a synthetic resin by vibrating the first member and the second member by pressing and abutting the joined pieces. The vibration welding method is characterized in that the tip of the narrower joining piece is provided in advance in a sectional shape having at least two projecting portions.

The most remarkable point in the present invention is that the protruding portion is provided in advance at the tip of the one narrow joining piece. As the shape of the protrusion, various shapes can be taken as described later. And at least two projections are provided, whereby a recess is provided between the projections. In addition, the tip of the protruding portion does not necessarily need to be provided in a knife edge shape.
It can be provided in a curved shape or a flat shape.

As the synthetic resin constituting the first member and the second member, for example, a thermoplastic resin such as PMMA (methacrylic resin), ABS resin, AAS resin, PA (polyamide resin) may be used. it can. Further, the synthetic resin of the first member and the synthetic resin of the second member may be the same or different.

Next, the operation of the present invention will be described. In the present invention, as described above, the cross-sectional shape is such that two or more of the protruding portions are provided at the tip of one of the joining pieces in advance. Therefore, when the joining piece having the projecting portion is pressed against the other joining piece and vibrated, the generation of burrs due to the molten resin can be largely suppressed.

The reason is considered as follows. That is, the narrow joining piece is provided with the two or more projecting portions, and the recess is naturally formed between them. Therefore, when the two joint pieces are brought into contact with each other under pressure and vibrated, first, melting starts at the tip portions of the two or more projecting portions.

Then, the molten resin rises to the surface side of each of the protrusions. That is, the molten resin protrudes not only around the narrow joint piece but also at the above-mentioned concave portion formed between two or more projecting portions. The molten resin in the recess is prevented from protruding around the joint piece. Therefore, it is considered that the amount of the molten resin protruding around the narrow bonding piece can be significantly reduced as compared with the conventional case. Therefore, according to the vibration welding method of the present invention, the occurrence of burrs formed by cooling and solidifying the raised molten resin can be suppressed as compared with the conventional method.

Further, in the present invention, since the two or more protrusions are provided on the joint piece, the resulting welded portion has an uneven joint boundary surface due to the influence of the protrusion. Therefore, the bonding strength can be improved as compared with the related art by the anchor effect (wedge effect) and the increase in the bonding area due to the uneven shape. The effect of improving the bonding strength can be obtained particularly effectively in the shear direction, that is, in the direction perpendicular to the pressing direction during vibration welding.

Next, as in the second aspect of the present invention, it is preferable that the protruding portion has an acute angle. In this case, the amount of molten resin generated first can be reduced, and furthermore, the generation of burrs can be suppressed.

Further, as in the third aspect of the present invention, the shape of the projecting portion is preferably substantially W-shaped in cross section. In this case, the protrusion can be easily formed.

Further, it is preferable that the distance between the tips of the projecting portions located at both ends is the same as the width dimension of the joining piece. In this case, the recess between the protruding portions can be made large, so that the amount of the molten resin protruding around the joining piece can be further reduced.

Further, as in the invention described in claim 5, the projecting portion can be provided asymmetrically with respect to the center axis of the joining piece. In this case, the molten resin that protrudes around the narrow joining piece can be biased to one side, so that burr generation on the other side can be particularly reduced.

Next, there are the following inventions as vibration welded articles having excellent joining strength. That is, as in the invention according to claim 6, a vibration welded product obtained by welding a first member and a second member made of a synthetic resin by vibrating the first and second joining pieces by pressing and contacting each other. In addition, there is a vibration welded product characterized in that the welded portion of the above-mentioned joint piece has a corrugated shape in which the joint boundary has irregularities.

The most remarkable point in the present invention is that the bonding boundary of the welded portion has a corrugated shape having irregularities. In this case, a so-called anchor effect and an increase in a joint area can be obtained by the corrugated shape having the irregularities. Therefore, the vibration welded article of the present invention can improve the joining strength as compared with the conventional vibration welded article having a smooth joining boundary surface.

Next, as in the invention according to claim 7, it is preferable that the welded portion of the welded article is welded by the vibration welding method according to any one of claims 1 to 5. In this case, a corrugated shape having irregularities can be easily provided on the joint boundary surface with the plurality of protrusions provided on the joint piece as a starting point.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A vibration welding method and a vibration welding product according to an embodiment of the present invention will be described with reference to FIG. In this example, as shown in FIG. 1, a first member 1 and a second member 2 made of a synthetic resin are welded by vibrating the joint pieces 10 and 20 by pressing and contacting each other. The distal end of the joining piece 10 having a smaller width is provided in advance in a sectional shape having two projecting portions 12.

In the present embodiment, the protruding portion 12 is provided as shown in FIG.
As shown in (a), it has an acute angle and a substantially W-shaped cross section. In addition, the two protrusions 12 are provided such that the distance between the tips is equal to the width of the joint piece 10.
It is provided symmetrically with respect to its central axis.

In vibration welding the first member 1 and the second member 2, as shown in FIG.
First, the joint pieces 10 and 20 are brought into pressure contact with each other. Next, vibration is applied to the first member 1 and the second member 2,
Friction heat is generated between the joining pieces 10 and 20.

As a result, first, the contact portion between the projecting portion 12 of the joining piece 10 and the joining piece 20 starts melting. Then, by continuously applying the vibration, the protrusion 12 is gradually shortened and the molten resin is increased, and the molten resin is cooled and solidified to complete the vibration welding.
As shown in FIG. 1 (b), the burr 99 generated in the obtained vibration welded product 5 is significantly suppressed and smaller than the conventional one (see FIGS. 6 (b) and 7). Therefore, the obtained vibration welded product 5 has excellent appearance characteristics.

The reason why the generation of the burrs 99 can be suppressed as described above is considered as follows. That is, the joint piece 10 is provided with the two protrusions 12 so that the recess 19 is formed between them. Therefore, the molten resin generated in the initial stage of vibration welding also enters the inside of the recess 19. Therefore, the amount of protrusion to the periphery of the joining piece 10 is significantly reduced as compared with the related art, and the burr 99 generated around the joining piece 10 is suppressed as compared with the related art.

Next, as shown in FIG. 1 (b), the joining boundary portion 50 of the welded portion in the obtained vibration welded product 5 had a corrugated shape having irregularities. That is, there is a mountain-shaped projection 51 at the center, and the left and right sides have a gentle curved shape with a downward convex. This wavy shape is considered to have been formed by the presence of the two protrusions 12.

The presence of the corrugated joining boundary portion 50 improves the joining strength of the vibration welded product 5 as compared with the related art. In particular, the joining strength in the direction perpendicular to the pressing direction during vibration welding is greatly improved. This is considered to be because the so-called anchor effect (wedge effect) can be obtained by the unevenness of the joining boundary portion 50 and the joining area can be increased.

As described above, in the present embodiment, by performing the above-described vibration welding method, it is possible to obtain a vibration welded product 5 having a small burr at the time of welding and having excellent joining strength.

Embodiment 2 In this embodiment, as shown in FIG. 2A, left and right asymmetric protruding portions 13 and 14 are provided on the joining piece 10. That is, one protruding portion 13 is longer and the other protruding portion 14 is slightly shorter. Others are the same as the first embodiment. In this case, in the initial stage of vibration welding, one of the protrusions 1
Only the three sides melt. Also, this projecting portion 13 is
In (a), the left side is straight, and the right side is provided at an acute angle with an inclined shape.

For this reason, the molten resin generated by the joining pieces 10 and 20 is not applied to the projecting portions 13 shown in FIG.
, And the occurrence of the protrusion 13 on the left side is suppressed. Therefore, the flow of the molten resin is entirely deviated toward the protruding portion 14, and the burr generated on the protruding portion 13 can be particularly reduced. Further, although the burr generated on the protruding portion 14 side is larger than that on the protruding portion 13 side, it can be made sufficiently smaller than before.
Otherwise, the same operation and effect as those of the first embodiment can be obtained.

Third Embodiment As shown in FIG. 3, this embodiment is an example in which the tip of the joint piece 10 in the first embodiment is provided with four projecting portions 15 to 18 symmetrically. Others are the same as the first embodiment. In this case, the same operation and effect as those of the first embodiment can be obtained.

Embodiment 4 In this embodiment, the effect of the vibration welding method of Embodiment 1 was quantitatively measured. That is, as shown in FIG. 4 (a), when the joint piece 10 having the two protrusions 12 similar to the first embodiment is used (Example E4), and as shown in FIG. The size of the burr after vibration welding was measured when the joint piece 10 having the protrusion 6 was used (Comparative Example C4). In each case, the joining piece 10
Has a width W of 1.0 mm and a length D of the protrusion is 1.0 mm.

As shown in FIG. 7, the measured value of the size of the burr is obtained by measuring the maximum dimension a in the vertical direction and the dimension b in the horizontal direction. (Amount of protrusion (mm)). FIG. 5 shows the measurement results. In the figure, the horizontal axis represents the difference between Example E4 and Comparative Example C4, and the vertical axis represents the amount of protrusion of burrs (mm).

As can be seen from the drawing, it can be seen that the protrusion of the burr can be reduced to about half by providing two protrusions 15 as in the first embodiment.

In each of the above embodiments, FIG.
As shown in FIG. 4, an example is shown in which the tip portions of the protruding portions 12 to 18 are sharpened like a knife edge. Instead of this, it is also possible to make the shape of the foremost part of the protruding portions 12 to 18 into a curved surface or a flat surface. In this case, the same operation and effect as those of the first to fourth embodiments can be obtained.

[0035]

As described above, according to the present invention, it is possible to provide a vibration welding method and a vibration welding product capable of suppressing the generation of burrs during welding and improving the bonding strength.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment, and FIG.
Explanatory drawing which shows the cross-sectional shape of the joining piece of a 1st member and a 2nd member after joining.

FIGS. 2A and 2B show a second embodiment of the present invention;
Explanatory drawing which shows the cross-sectional shape of the joining piece of a 1st member and a 2nd member after joining.

FIG. 3 is an explanatory diagram showing a cross-sectional shape of a joining piece of a first member according to a third embodiment.

FIG. 4 (a) is an embodiment E4 according to the fourth embodiment.
(B) Explanatory drawing which shows the cross-sectional shape of the joining piece of the 1st member of comparative example C4.

FIG. 5 is an explanatory diagram showing an amount of protrusion of a burr according to a fourth embodiment.

FIG. 6 is an explanatory view showing a cross-sectional shape of a joining piece of a first member and a second member before (a) joining and after (b) joining in a conventional example.

FIG. 7 is an explanatory view showing another cross-sectional shape of a joining portion between a first member and a second member in a conventional example.

[Explanation of symbols]

 1. . . First member, 10, 20. . . Bonding piece, 12-18. . . Protrusions, 19. . . Recesses, 2. . . Second member, 5. . . Vibration welded product, 50. . . Joint boundaries,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuji Nagata 1 Ogataai Ogataai, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyota Gosei Co., Ltd. F term (reference) in Toyoda Gosei Co., Ltd. 4F211 AD05 AD24 AG07 AG24 AG28 AH81 AM33 TA01 TC08 TD07 TH02 TH18 TN20 TQ05

Claims (7)

[Claims] 1. A method of welding a first member and a second member made of a synthetic resin by vibrating a joint piece by pressing and contacting the joint piece with each other. A vibration welding method characterized in that the vibration welding method is provided in advance in a sectional shape having at least two projecting portions. 2. The vibration welding method according to claim 1, wherein the protrusion has an acute angle. 3. The vibration welding method according to claim 1, wherein said projecting portion has a substantially W-shaped cross section. 4. The method according to claim 1, wherein:
A vibration welding method, wherein the distance between the tips of the protrusions located at both ends is the same as the width dimension of the joining piece. 5. The method according to claim 1, wherein:
The method according to claim 1, wherein the projecting portion is provided asymmetrically with respect to a center axis of the joining piece. 6. A vibration welded product in which a first member and a second member made of a synthetic resin are welded by vibrating a joint piece by pressing and contacting each other, and a welded portion of the joint piece is provided. A vibration welded product characterized in that the joint boundary has a corrugated shape having irregularities. 7. A vibration welded product according to claim 6, wherein the welded portion of the welded product is welded by the vibration welding method according to any one of claims 1 to 5.