JP2007038422A - Ultrasonic welding method for resin component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deformation of an adherend and to secure high attachment strength in an ultrasonic welding method for a resin component in which the resin component is integrated with the adherend. <P>SOLUTION: When ultrasonic machining is applied to an ultrasonic machining point 40 by an ultrasonic horn 50 with a clip fitting seat (resin component) 30 superposed on a roof trim main body (adherend) 20, a projection 33 for a welding part is formed. A space 34 for absorbing a molten resin M is formed around the projection 33, or a concave groove 37 or a recess 38 to be a passage for the molten resin M is set at the ultrasonic machining point 40, so that sufficient welding strength is secured without having an adverse effect of heat or a press pressure from the ultrasonic horn 50 on the adherend 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic welding method for resin parts in which resin parts are integrated with an adherend by ultrasonic processing, and in particular, the adherend is deformed by the press pressure of an ultrasonic horn or heat at that time. The present invention relates to an ultrasonic welding method for resin parts that can be reliably prevented and can maintain a strong welding strength.

  Conventionally, as a method of fixing a resin part on one surface of an adherend, an adhesive fixing method using an adhesive, a high frequency welder welding method using high frequency welder welding, applying ultrasonic vibration, and heating and melting the resin part. An integrated ultrasonic welding method or the like is known. Among them, the adhesive fixing method has a problem that the process of applying and drying the adhesive is prolonged and an organic solvent is often used, so that the working environment is deteriorated. Further, the high frequency welder welding method depends on the high frequency welder characteristics of the resin component, and the degree of freedom in selecting the material is often limited. In this regard, the ultrasonic welding method is preferable from the viewpoint of work environment and can be used in a wide range since it can be integrated with any resin having any physical property.

  An outline of the ultrasonic welding method will be described with reference to FIGS. First, the resin component 2 is superposed on the adherend 1, and the ultrasonic horn 3 is appropriately pressed against the ultrasonic processing point A with a press pressure, and ultrasonic vibration of a predetermined frequency is applied for a predetermined time, as shown in FIG. As described above, a part of the resin component 2 (the portion indicated by the hatched portion in the figure) is melted on the adherend 1 so that the resin component 2 can be firmly integrated with the adherend 1 in a short time. The ultrasonic welding of the resin component 2 using the ultrasonic horn 3 is described in detail in Patent Document 1.

JP-A-2-22034

  As described above, in the ultrasonic welding method widely used, since heating is performed in a state where pressure is applied by the ultrasonic horn 3, there is often a problem that the adherend 1 is deformed as shown in FIG. ing. As a factor of this deformation, the influence of heat at the time of press welding by the ultrasonic horn 3 and ultrasonic welding can be considered.

  Therefore, in the existing ultrasonic processing, in order to avoid such deformation, the press pressure cannot be applied excessively, and the processing time must be completed in a short time. The amount is limited, it is difficult to stably obtain a sufficient welding strength, and there is an urgent need to maintain a strong welding strength while avoiding deformation. In particular, recently, light-weight materials are used as the base material for interior parts such as roof trims, and these light-weight materials tend to be deformed by the influence of press pressure and heat during ultrasonic welding.

  The present invention has been made in view of such circumstances, and when the resin component is welded and integrated to the adherend with an ultrasonic horn, the adherend can be reliably prevented from being deformed and always has a strong welding strength. It is an object of the present invention to provide an ultrasonic welding method for resin parts that can secure the above.

  In order to solve the above-described problems, the present invention provides a resin component by placing a resin component on one surface of an adherend, appropriately pressing an ultrasonic horn from the resin component side with a pressing pressure, and applying ultrasonic vibration for a predetermined time. In the ultrasonic welding method for resin parts, in which a part of the resin parts is fused and integrated with the adherend, a welding sill projection is provided on the ultrasonic horn contact side of the resin part. By providing a space for accommodating the molten resin that becomes a welding skirt around the protrusion, and pressing the ultrasonic horn on the upper surface of the protrusion to melt the protrusion, the molten resin is accommodated in the space. It is characterized in that a welding swarf is secured and a resin part is integrally welded to the adherend.

  Here, as a combination of an adherend and a resin part, a roof trim, a clip mounting seat attached to a predetermined position on the back surface thereof, a top / bottom split type door trim lower, a pocket back cover attached to the back surface, etc. are conceivable. However, the application is not limited as long as the resin part on one side is partially melted by the ultrasonic welding process and the resin part is welded and integrated with the adherend. In addition, the resin parts are made of polyethylene resin, polypropylene resin, polystyrene resin, polyethylene terephthalate resin, polyvinyl alcohol resin, vinyl chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, ionomer resin. You may select suitably from resin, an acrylonitrile / butadiene / styrene (ABS) resin, etc. Furthermore, the adherend only needs to have rigidity to support the resin component, and may be appropriately selected from materials such as a resin base material, a corrugated board base material, and a foamed resin base material.

  As is clear from the above configuration, the resin component is overlaid on the adherend, and the ultrasonic horn is pressed against the upper surface of the welding sill projection provided on the resin component, so that the ultrasonic vibration of the predetermined frequency is predetermined. If time is added, the welding sill projection melts and the molten resin is accommodated in a space provided around the projection. Therefore, it is not necessary to apply an excessive press pressure by the ultrasonic horn, and the welding shiro is sufficiently secured by the protrusion, so that a sufficient welding strength can be obtained even if the pressing pressure is set low. It is possible to prevent the adherend from being deformed as much as possible.

  Furthermore, in a preferred embodiment of the present invention, the welding sill projection is supported by the mounting plate in a floating state by a support piece that crosses the cavity, and a bottom space for accommodating molten resin at the bottom of the projection. Is formed in communication with the void. According to this embodiment, since the protrusion is supported in a floating state by the support piece that crosses the void, when pressing pressure from an ultrasonic horn is applied to the upper surface of the protrusion, the protrusion is pressed to the adherend side. Since no pressure is applied, the press pressure of the ultrasonic horn can be set to a relatively large value, the melting process can be performed in a short time, and the welding efficiency can be increased.

  Next, in a preferred embodiment of the present invention, a resin component is placed on one surface of the adherend, an ultrasonic horn is appropriately pressed from the resin component side with a press pressure, and ultrasonic vibration is applied for a predetermined time. In an ultrasonic welding method for a resin part in which a part of the part is melted and the resin part is welded and integrated with the adherend, a concave portion for accommodating the molten resin is provided on the adherend contact side of the resin part. A groove is provided, and at the time of ultrasonic welding, the molten resin flows into the concave groove, and the molten resin that has flowed into becomes a welding scissors, and the resin parts are welded and integrated with the adherend. According to this embodiment, when the resin component is heated with the ultrasonic horn, the resin component is melted and the melted portion reaches the contact surface with the adherend. Furthermore, the molten resin flows into the concave groove starting from the melting site, and then the molten resin is cooled and solidified, so that a sufficient welding load can be secured, and the resin component is attached to the adherend. Can be securely fixed.

  Next, in a further preferred embodiment of the present invention, a resin component is placed on one surface of the adherend, an ultrasonic horn is appropriately pressed from the resin component side with a pressing pressure, and ultrasonic vibration is applied for a predetermined time. In the ultrasonic welding method for a resin part in which a part of the part is melted and the resin part is welded and integrated with the adherend, a concave portion is provided on the adherend contact side of the resin part. When pressurizing an ultrasonic processing point with an ultrasonic horn at the time of ultrasonic welding, the concave portion is depressed, thereby reducing the press pressure applied to the adherend. According to this embodiment, the portion in contact with the horn is heated and melted by the ultrasonic horn. When sufficiently melted, the concave portion is depressed, and the melted resin comes into contact with the adherend. After this state is reached, ultrasonic processing is stopped and the horn is released. Therefore, since the site | part to which the pressure by an ultrasonic horn applies and the site | part heated are different, a press pressure is not applied to a to-be-adhered body, but it can prevent as much as possible that a to-be-adhered body deform | transforms. Moreover, since the resin component is welded to the adherend in a sufficiently melted state, the welding strength is improved. Furthermore, since the depression contact does not occur until it is sufficiently melted, the melted amount of the molten resin and the contact time are stabilized, and variations in welding strength can be reduced.

  Furthermore, in a preferred embodiment of the present invention, the ultrasonic processing point on the bonding surface of the adherend and the resin part is provided with a small protrusion for promoting initial welding. According to this embodiment, since the small protrusion is provided on the upper surface or the lower surface of the welding white projection or a part of the side surface of the adherend of the resin component, an ultrasonic horn is applied to the resin component. Thus, when ultrasonic vibration is applied, the small protrusions are rapidly melted, so that the ultrasonic welding process can be performed smoothly.

  As described above, the ultrasonic welding method of the resin component according to the present invention, when the resin component is welded and integrated with the ultrasonic horn with respect to the adherend, while the projection for welding welding is projected on the resin component, Adopted a configuration to provide a space to accommodate the molten resin around the projection for welding welding, or to form a concave groove where the molten resin flows on the opposite side of the horn side of the resin part or a concave part that sinks during horn processing As a result, it is possible to secure a sufficient welding load without applying excessive press pressure to the adherend, so that it is possible to reliably prevent deformation of the adherend and to achieve a strong joint structure of resin parts. It has the effect of being able to.

  Hereinafter, embodiments of an ultrasonic welding method for resin parts according to the present invention will be described in detail with reference to the accompanying drawings. Note that the gist of the present invention is as described in the scope of claims, and the contents of the embodiments described below are merely examples of the present invention.

  1 to 10 show a first embodiment of the present invention. FIG. 1 is a perspective view of a roof trim having a clip mounting seat applied by applying the method of the present invention as seen from the back side, and FIG. FIG. 3 is a cross-sectional view showing the configuration of ultrasonic processing points in the clip mounting seat, FIG. 4 is an explanatory view showing a first embodiment of the method of the present invention, and FIG. FIG. 6 and FIG. 7 are cross-sectional views showing the configuration of the ultrasonic processing point, and FIGS. 8 to 10 are explanatory views showing modifications of the present invention.

  1 to 3, a roof trim 10 is trim-cut into a desired shape and is formed in a slightly curved shape toward the indoor side, and a roof trim body 20 is attached to the roof trim body 20. A clip mounting seat (resin component) 30 to be mounted and a mounting component such as a sun visor (not shown) are included. The roof trim body 20 is configured by pasting a skin such as a cloth or a non-woven fabric on the surface side of a base material formed from a mixed material of PP resin / foaming agent / glass fiber, if desired. Yes. The clip mounting seat 30 is fixed to the ultrasonic processing point 40 by ultrasonic welding at a predetermined position on the back surface of the roof trim body 20. And in the ultrasonic processing point 40, the deformation | transformation which bends indoors in the roof trim main body 20 side has not generate | occur | produced, and while the external appearance is favorable by favorable smooth feeling, as shown in FIG. By securing the welding shell, the clip mounting seat 30 is firmly and integrally integrated with the roof trim body 20.

  The first embodiment of the present invention will be described with reference to FIGS. 4 to 7. The clip mounting seat 30 has a smooth resin plate 31 and an embossed mounting seat body 32 integrally formed. At four corners corresponding to the ultrasonic processing point 40 of the plate-making plate 31, columnar welding white projections 33 projecting toward the ultrasonic horn 50 are formed, and around the welding white projection 33. The space 34 for accommodating the molten resin is provided symmetrically.

Then, in order to weld and fix the clip mounting seat 30 to a predetermined position on the back surface of the roof trim body 20 using the ultrasonic horn 50, as shown in FIG. If pressed and subjected to ultrasonic welding under conditions of processing time: 0.1 to 5.0 seconds, frequency: 18 to 40 kHz, press pressure: 0.5 to 3.0 kgf / cm ² , projection for welding white The upper part of 33 is melted, and the height dimension of the projection for welding welding 33 is equal to or slightly higher than that of the resin plate 31, so that the molten resin M flows into the void 34, and a lot of welding solder is generated. Therefore, as shown in FIG. 3, the clip mounting seat 30 is firmly integrated at a predetermined position of the roof trim main body 20. Further, since the welding sill projection 33 is set, the press pressure from the ultrasonic horn 50 is not excessively applied to the roof trim body 20 side, so that the deformation of the roof trim body 20 can be surely prevented.

  Next, FIGS. 8 and 9 show a modified example of the first embodiment of the present invention. As shown in FIG. 8, the support piece 35 crosses the space 34 in the outer periphery of the projection 33 for welding welding. The support piece 35 supports the welding white projection 33 in a state where the bottom surface is lifted from the lower surface of the resin plate 31. Therefore, also in this modified example, if the ultrasonic horn 50 is pressed against the upper surface of the welding sill projection 33 and ultrasonic welding is performed by applying a predetermined ultrasonic vibration, the molten resin M is placed in the void 34. The clip mounting seat 30 is firmly integrated with the back surface of the roof trim body 20 by being filled. In particular, in this modified example, the welding sill protrusion 33 is held in a state of being lifted upward, and the ultrasonic wave The press pressure from the horn 50 is hardly applied to the roof trim main body 20, and a bottom space 36 is newly formed on the bottom surface side of the welding sill projection 33, so that the molten resin M also enters this portion. Thus, since many welding scissors can be secured, the clip mounting seat 30 can be more firmly fixed to a predetermined position of the roof trim body 20.

  Next, FIG. 10 shows a further modification of the present invention. As shown in FIGS. 10A and 10B, a small projection 33 a and a bottom surface of the welding sill projection 33 are formed on the top surface of the welding sill projection 33. The small protrusions 33b are provided in a ring shape along the peripheral edges of the upper surface and the lower surface of the welding sill protrusion 33. Further, as shown in FIG. 10 (c), a small protrusion 34 a is also provided in an annular shape along the outer peripheral edge of the void 34 on the back surface of the resin plate 31 at a portion to be joined to the roof trim body 20. The small protrusions 33a, 33b, and 34a are superposed on the roof trim main body 20 with the clip mounting seat 30 and the ultrasonic horn 50 is pressed against the upper surface of the welding sill protrusion 33 to perform ultrasonic welding. Since the small protrusions 33a, 33b, and 34a are first melted, the melting is started and ultrasonic welding can be performed smoothly.

  FIGS. 11 to 15 show a second embodiment of the present invention. Like the first embodiment, the clip mounting seat (resin part) 30 is ultrasonically fixed to the roof trim body (adhered body) 20. The point used for a use is the same as the 1st example. In the second embodiment, a concave groove 37 having a V-shaped cross section is formed in a cross shape on the back surface 31a of the resin plate 31 in the clip mounting seat 30 (the surface in contact with the roof trim body 20). Then, an ultrasonic machining point 40 (indicated by a dotted line in the figure) is the vicinity of the intersection of the concave grooves 37. Then, if the resin plate 31 of the clip mounting seat 30 is superposed on a predetermined position on the back surface of the roof trim body 20 that is the adherend, an appropriate pressure is applied by the ultrasonic horn 50 and ultrasonic vibration is applied to melt it. 12 and 13, the molten resin M flows along the concave groove 37 to form a sufficient welding white, and the molten resin M is cooled and solidified, so that the resin plate 31 has a roof trim. It is securely fixed to the main body 20.

  Therefore, a sufficient welding load can be secured by the concave groove 37 without applying an excessive press pressure from the ultrasonic horn 50 to the clip mounting seat 30. As a result, the roof trim body 20 is not deformed, and the clip mounting seat 30 can be firmly fixed to the roof trim body 20. Further, as shown in FIG. 14 (a), the concave groove 37 of the clip mounting seat 30 is omitted, while the concave groove 21 is formed in the roof trim body 20, or as shown in FIG. 14 (b) You may provide so that both the ditch | groove 37 and the ditch | groove 21 of the mounting seat 30 may oppose. And as shown to Fig.14 (a), (b), welding intensity | strength can be raised more according to the anchor effect which the molten resin M bites into the roof trim main body 20. FIG. In particular, as shown in FIG. 14B, if the concave grooves 37 and 21 are formed on both sides, the cross-sectional area of the groove through which the molten resin M flows can be increased. Can be strong. Further, as shown in FIGS. 15A and 15B, if a small protrusion 37a is formed around the groove 37, the small protrusion 37a is first melted at the time of ultrasonic welding, thereby smoothly Ultrasonic machining can be advanced.

  FIGS. 16 to 20 show a third embodiment of the present invention. Also in this third embodiment, the roof trim main body 20 is used as an adherend, and a clip mounting seat which is a resin part on the back surface thereof. 30 is applied to a method of ultrasonic welding. FIG. 16 is an explanatory view showing an outline of the ultrasonic welding method of the third embodiment, FIGS. 17 and 18 are explanatory views showing respective steps in the ultrasonic welding method, and FIGS. 19 and 20 are explanatory views showing modifications. It is.

  In the third embodiment, a recess 38 is formed on the back surface of the resin plate 31 in the clip mounting seat 30 (the surface in contact with the roof trim body 20). Accordingly, as shown in FIG. 17, when the ultrasonic horn 50 is pressed against the ultrasonic processing point 40 of the clip mounting seat 30 and pressed with a predetermined press pressure, and ultrasonic vibration is applied, the portion corresponding to the recess 38 is formed. Melts and sinks. Then, as shown in FIG. 18, the clip mounting seat 30 is welded and fixed to the roof trim body 20, which is an adherend, by an ultrasonic machining point 40 by the press pressure of the ultrasonic horn 50. And in this 3rd Example, since the site | part which the pressure by the ultrasonic horn 50 applies and the site | part heated are different, the roof trim main body 20 which is a to-be-adhered body does not deform | transform. Furthermore, since the clip mounting seat 30 is bonded to the roof trim body 20 in a sufficiently melted state, the welding strength is improved. In addition, since the depression contact does not occur until it is sufficiently melted, there are various advantages such as that the molten amount of the molten resin M and the contact time are stabilized, and the variation in welding strength can be reduced.

  Next, FIG. 19 shows a modification of the third embodiment. In FIG. 19A, the concave portion 38 of the clip mounting seat 30 is omitted, while the concave portion 22 is formed in the roof trim body 20. ing. Further, in FIG. 19B, the recess 22 is formed on both sides of the clip mounting seat 30 at a location corresponding to the recess 38. As shown in FIG. 19A, since the recess 38 is not formed in the clip mounting seat 30, the clip mounting seat 30 can be shared for other uses. Further, in this case, during ultrasonic processing by the ultrasonic horn 50, the molten resin M flows into the concave portion 22 of the roof trim main body 20, and strong integration is obtained by sufficient welding scissors and an anchor effect. Furthermore, as shown in FIG. 19B, when the recesses 38 and 22 are formed in both the clip mounting seat 30 and the roof trim main body 20, the amount of movement of the ultrasonic horn 50 when it is depressed increases, and In the case of depression, ON / OFF control of ultrasonic processing is easy to perform and a large number of welding spots can be secured, so that a stronger welding strength can be secured. Furthermore, as shown in FIG. 20, if the small annular protrusions 38a and 38b are formed at the ultrasonic processing point 40, the small protrusions 38a and 38b are first melted to improve the processing performance in ultrasonic processing. To do.

  The first to third embodiments described above are applied to a structure in which the clip mounting seat 30 is integrated at a predetermined position on the back surface of the roof trim main body 20 by ultrasonic welding. In addition to the use, the adherend can be applied to a wide range such as a resin panel, a corrugated board base, and a paper base other than the roof trim main body 20. Further, the dimensions and shapes of the welding sill projection 33, the void 34 for absorbing the molten resin, the concave groove 37, the concave portion 38, and the like are not particularly limited, and can be appropriately varied.

It is the external view which looked at the roof trim which applied the method of this invention and attached the clip attachment seat from the back side. It is a top view which shows the clip attachment seat attached to the roof trim shown in FIG. It is sectional drawing which shows the attachment structure of the clip attachment seat in the roof trim shown in FIG. It is a 1st example of the ultrasonic welding method of the resin parts concerning the present invention, and is a perspective view showing the ultrasonic welding method of a clip attachment seat. It is a top view which shows the ultrasonic processing point in the ultrasonic welding method of the clip attachment seat shown in FIG. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is sectional drawing which shows the state after completion of ultrasonic processing of the ultrasonic processing point shown in FIG. It is a top view of the ultrasonic processing point which shows the modification of the ultrasonic welding method in 1st Example of this invention. 9A is a cross-sectional view taken along line AA, and FIG. 8B is a cross-sectional view taken along line BB. It is each sectional drawing which shows the modification of 1st Example of this invention. (A) The perspective view which looked at the clip mounting seat used for 2nd Example of the ultrasonic welding method of the resin component which concerns on this invention from the back surface side, (b) It is CC sectional view taken on the line in (a). It is the top view which looked at the clip attachment seat shown in FIG. 11 from the back surface side. It is explanatory drawing which shows the state at the time of the ultrasonic welding process of the clip attachment seat shown in FIG. It is each sectional drawing which shows the modification of 2nd Example of this invention. It is the top view seen from the back surface side which shows the clip mounting seat in 2nd Example of this invention method, (b) It is principal part sectional drawing. It is explanatory drawing which shows 3rd Example of the ultrasonic welding method of the resin component which concerns on this invention. It is explanatory drawing which shows the state in the middle of the process in the ultrasonic welding method shown in FIG. It is explanatory drawing which shows the state at the time of the completion of a process in the ultrasonic welding method shown in FIG. It is each explanatory drawing which shows the modification of 3rd Example of the ultrasonic welding processing method which concerns on this invention. It is each explanatory drawing which shows the modification of 3rd Example of the ultrasonic welding processing method which concerns on this invention. It is explanatory drawing which shows the prior art example which welds and fixes a clip attachment seat to a roof trim main body with an ultrasonic horn. It is explanatory drawing which shows the prior art example which welds and fixes a clip attachment seat to a roof trim main body with an ultrasonic horn. It is explanatory drawing which shows the malfunction point in the conventional ultrasonic welding method.

Explanation of symbols

10 Roof trim 20 Roof trim body (adhered body)
21 concave groove 22 concave 30 clip mounting seat (resin part)
31 Resin plate 32 Mounting seat body 33 Welding protrusion 33a, 33b, 34a, 37a, 38a, 38b Small protrusion 34 Space 35 Support piece 36 Bottom space 37 Concave groove 38 Concave 40 Ultrasonic machining point 50 Ultrasonic horn

Claims (5)

The resin component (30) is placed on one surface of the adherend (20), the ultrasonic horn (50) is appropriately pressed from the resin component (30) side with a pressing pressure, and ultrasonic vibration is applied for a predetermined time to apply the resin component. In the ultrasonic welding method of the resin component (30) in which a part of (30) is melted and the resin component (30) is integrally welded to the adherend (20),
A projection for welding welding (33) is provided on the side of the resin component (30) that contacts the ultrasonic horn (50), and a molten resin (M) that forms welding welding is formed around the projection (33). A space (34) for housing is provided, the ultrasonic horn (50) is pressed against the upper surface of the protrusion (33) to melt the protrusion (33), and then the molten resin (M) is placed in the space (34). A method for ultrasonic welding of resin parts, comprising securing a welding shell and integrating the resin part (30) on the adherend (20).   The projection for welding welding (33) is supported by the mounting plate (31) in a floating state by a support piece (35) crossing the void (34), and a molten resin (M) is placed on the bottom of the projection (33). The method for ultrasonic welding of resin parts according to claim 1, characterized in that a bottom space (36) for accommodating is formed in communication with a void (34). The resin component (30) is placed on one surface of the adherend (20), the ultrasonic horn (50) is appropriately pressed from the resin component (30) side with a pressing pressure, and ultrasonic vibration is applied for a predetermined time to apply the resin component. In the ultrasonic welding method of the resin component (30) in which a part of (30) is melted and the resin component (30) is integrally welded to the adherend (20),
A concave groove (37) for accommodating the molten resin (M) is provided on the adherend (20) abutting side of the resin component (30). During the ultrasonic welding process, the molten resin (M ) Flows into the concave groove (37), and the molten resin (M) that has flown into becomes a welding scissors, and the resin component (30) is welded and integrated with the adherend (20). Welding method. The resin component (30) is placed on one surface of the adherend (20), the ultrasonic horn (50) is appropriately pressed from the resin component (30) side with a pressing pressure, and ultrasonic vibration is applied for a predetermined time to apply the resin component. In the ultrasonic welding method of the resin component (30) in which a part of (30) is melted and the resin component (30) is integrally welded to the adherend (20),
A concave portion (38) is provided on the adherend (20) contact side of the resin component (30), and an ultrasonic horn (50) is used for ultrasonic processing point (40) during ultrasonic welding. An ultrasonic welding method for resin parts, wherein the pressing pressure applied to the adherend (20) is reduced by the depression of the recess (38) when the pressing pressure is applied. Small protrusions (33a, 33b, 34a, 37a, 38a, 38b) for promoting initial welding are provided at the ultrasonic processing point (40) on the bonding surface of the adherend (20) and the resin component (30). The method for ultrasonic welding of resin parts according to any one of claims 1 to 4, wherein the resin parts are ultrasonically welded.

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