Joining structure of synthetic resin components

Abstract

To provide a joint structure of a synthetic resin member with elevated bond strength.SOLUTION: Disclosed is a joint structure of an upper trim main body 31 and a trim bracket 32 which are made of a synthetic resin, wherein the upper trim main body 31 is provided with a welding boss 40A having a hollow structure. A tip of the welding boss 40A serves as a branching pieces 42 split to three parts in a circumferential direction. In a joint piece 32d of the trim bracket 32, three arc-shaped hole parts 60 arranged in a circumferential direction corresponding to each of the three branching pieces 42 are formed. A portion surrounded by the three arc-shaped hole parts 60 at the joint piece 32d serves as a bearing surface 32x. A tip of the branching piece 42 inserted with the arc-shaped hole part 60 is welded to a peripheral part of the arc-shaped hole part 60 including the inner bearing surface 32x as a welding head 43 by fusion-deformation due to heating.SELECTED DRAWING: Figure 4

Description

Technical Field

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[0001] The present invention relates to a structure for joining two members made of synthetic resin by welding.

Background Art

[0002] In order to join two members made of synthetic resin, it is known to insert a welding boss provided on the first member into a through hole formed in the second member and weld the tip of the welding boss to the peripheral portion of the through hole.

[0003] In Patent Document 1 below, as shown in FIGS. 8(A) and (B), a door trim 1 made of synthetic resin is composed of a lower trim 2 and an upper trim 3, and a structure for joining the lower trim 2 and the upper trim 3 by welding is disclosed.

[0004] <​​​​​​​​​​​​​​​​​​​​​​​In the joint structure of Patent Document 1, as shown in Figure 8(B), only the peripheral edge of the welding head 2b is welded to the joint piece 3a, contributing to the joining of the lower trim 2 and the upper trim 3, resulting in weak joint strength. To increase the joint strength, setting the tip of the melting welding boss 2a to be longer resulted in a longer welding time.

[0007] The welding boss 2a is formed in a cylindrical shape to prevent shrinkage on the design surface of the lower trim 2. Therefore, when the tip of the welding boss 2a is melted and deformed to form the welding head 2b, the center of the welding head 2b sometimes melts into the inside of the welding boss 2a and reaches the back surface of the lower trim 2. This could potentially damage the appearance of the design surface. [Means for solving the problem]

[0008] The present invention has been made to solve at least one of the above problems, and one aspect of the present invention is a bonding structure for synthetic resin members, A joining structure for synthetic resin members comprising two members made of synthetic resin, wherein a hollow welding boss provided on the first member is inserted through a through hole formed in the second member, and the tip of the welding boss is welded to the periphery of the through hole, thereby joining the first member and the second member, The tip of the above-mentioned welded boss is divided into multiple branched sections in the circumferential direction. The through-holes are formed as a plurality of arc-shaped holes arranged circumferentially, corresponding to each of the plurality of branch pieces, and the portion of the second member surrounded by the plurality of arc-shaped holes forms the inner seating surface. The tip of the branched piece inserted into the arc-shaped hole is welded to the peripheral edge of the arc-shaped hole, including the inner seating surface.

[0009] According to the above configuration, in the second member, the inner seating surface allows welding to occur not only on the radially outer side of the welding boss but also on the inner side. In other words, not only the peripheral edge of the welding head but also the central part is subjected to welding, thereby increasing the joint strength. Consequently, the length of the welding boss required to obtain the joint strength can be shortened, and the welding time can be reduced. Furthermore, the inner seating surface prevents molten material from entering the base end side of the welded boss, thereby preventing any impact on the appearance of the surface of the first member opposite to the welded boss.

[0010] Preferably, a sub-boss is provided on the inner seating surface of the second member, which protrudes in the same direction as the protruding direction of the branched piece and is subject to welding. According to the above configuration, by providing a sub-boss, the length of the welding boss required to obtain joint strength can be shortened, and the area in contact with the welding horn can be increased, thereby improving heating efficiency and further shortening the welding time. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a bonding structure for synthetic resin members that enhances bonding strength. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of a door trim to which the joining structure according to the first embodiment of the present invention is applied, viewed from the rear on the outside of the vehicle interior. [Figure 2] This is an enlarged perspective view showing the welded boss of the upper trim body and the connecting piece of the trim bracket, which form the same joint structure, separated. [Figure 3] This figure shows the state in which the branched portion of the welded boss is inserted into the arc-shaped hole of the joint portion, where (A) is a perspective view and (B) is a plan view. [Figure 4] Figure 3(B) is a cross-sectional view along the line IV-IV, where (A) shows the state before welding and (B) shows the state after welding. [Figure 5] This is an enlarged perspective view showing a joining piece that forms a joining structure according to a second embodiment of the present invention. [Figure 6] This figure shows the state in which the branched portion of the welding boss is inserted into the arc-shaped hole of the joining piece of the second embodiment, where (A) is a perspective view and (B) is a plan view. [Figure 7]FIG. 6(B) is a cross-sectional view taken along line VII-VII, where (A) shows the state before welding and (B) shows the state after welding. [Figure 8] FIG. 8 shows a door trim to which a conventional joining structure is applied, where (A) is an exploded perspective view of the main part and (B) is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 8(A), showing the state after welding.

MODE FOR CARRYING OUT THE INVENTION

[0013] [First Embodiment] Hereinafter, a joining structure of a synthetic resin member according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4. This embodiment applies the present invention to the joining structure between an upper trim body and a trim bracket in a vehicle door trim.

[0014] The door trim 10 shown in FIG. 1 is an interior material attached to a vehicle door panel (not shown), and includes a lower trim 20 and an upper trim 30, with the vehicle interior side being the design surface. The upper trim 30 is composed of an upper trim body 31 (first member) and a trim bracket 32 (second member) joined to the outer side of the vehicle exterior at the upper end of the upper trim body 31.

[0015] The upper trim body 31 is formed by injection molding with a synthetic resin such as polypropylene (PP) or polypropylene filled with filler (PPF). The trim bracket 32 is also an injection molded product made of synthetic resin and may be composed of the same material as the upper trim body 31.

[0016] The upper trim body 31 has two types of welding bosses 40A and 40B used for joining with the trim bracket 32 at the upper end of the back surface on the outer side of the vehicle exterior. A plurality (four in this embodiment) of the welding bosses 40A and 40B are arranged in the longitudinal direction of the vehicle, and each projects outward in the vehicle width direction on the outer side of the vehicle exterior.

[0017] The trim bracket 32 extends in the longitudinal direction of the vehicle and has an upper wall portion 32a, an outer wall portion 32b that hangs down from the outside of the vehicle compartment of the upper wall portion 32a and to which the weather strip S is attached, and an inner wall portion 32c that hangs down from the vehicle compartment side of the upper wall portion 32a. A joining piece portion 32d hangs down from the lower end of the inner wall portion 32c.

[0018] The joining piece portion 32d is used for joining with the upper trim main body 31, and a plurality (four in this embodiment) are formed in the longitudinal direction of the vehicle corresponding to the arrangement of the plurality of welding bosses 40A and 40B. As will be described later, among these joining piece portions 32d, those corresponding to the welding boss 40A have a different shape of the through hole formed compared to those corresponding to the welding boss 40B.

[0019] Regarding the joining structure between the welding boss 40A and the joining piece portion 32d in the upper trim main body 31 and the trim bracket 32 having the above configuration, it will be described with reference to FIGS. 2 to 4. First, the welding boss 40A and the joining piece portion 32d will be described.

[0020] As shown in FIG. 2, the welding boss 40A has an elongated hollow structure and is formed in an annular shape in a plan view. The base end side of the welding boss 40A is a cylindrical portion 41. This prevents sink marks from occurring on the design surface of the upper trim main body 31 on the side opposite to the welding boss 40A.

[0021] The tip end side of the welding boss 40A protrudes from the tip end of the cylindrical portion 41 and is three branch piece portions 42 of the same shape arranged at equal intervals in the circumferential direction. The inner surface 42a and the outer surface 42b of the branch piece portion 42 are flush with the inner circumferential surface 41a and the outer circumferential surface 41b of the cylindrical portion 41, respectively, and have the same curvature.

[0022] Around the welding boss 40A, three ribs 51 arranged at equal intervals in the circumferential direction and three ribs 52 arranged at equal intervals in the circumferential direction between these ribs 51 are provided. The rib 51 connects the back surface of the upper trim body 31 to the cylindrical portion 41. The end face 51a of the rib 51 facing outward from the vehicle interior and the front end face 41c of the cylindrical portion 41 are formed flush with each other.

[0023] The rib 52 connects the back surface of the upper trim body 31, the cylindrical portion 41, and the branched portion 42. The end face 52a of the rib 52 facing outward from the vehicle interior is formed to form a virtual coplane with the end face 51a of the rib 51 and the tip face 41c of the cylindrical portion 41. The portion of the rib 52 connected to the branched portion 42 has a wedge-shaped tip 52b that tapers radially in the direction of the welded boss 40A.

[0024] The joining piece 32d has three annular, fan-shaped arc-shaped holes 60 formed as through holes for inserting the branched piece 42 of the welding boss 40A. The three arc-shaped holes 60 are arranged at equal intervals in the circumferential direction, corresponding to the three branched pieces 42.

[0025] The arc-shaped hole 60 is formed to be slightly larger than the outer shape of the branched piece 42 so that the branched piece 42 and the wedge-shaped piece 52b can be inserted through it. The inner arc surface 61 and the outer arc surface 62 of the hole wall of the arc-shaped hole 60 are formed to be concentric with the inner surface 42a and the outer surface 42b of the branched piece 42 in a plan view (see Figure 3(B)) when the branched piece 42 is inserted through the arc-shaped hole 60.

[0026] The portion of the joining piece 32d surrounded by the three arc-shaped holes 60 forms the inner seating surface 32x, which is used for joining with the welding boss 40A by welding, as will be described later.

[0027] Next, the formation of the joint structure by the welding boss 40A and the joining piece 32 as described above will be explained. As shown in Figure 3, the three branched portions 42 and wedge-shaped portion 52b of the welded boss 40A are inserted into the three arc-shaped holes 60 of the joining portion 32d, respectively, and protrude from the arc-shaped holes 60. At this time, the joining portion 32d can be brought into contact with the tip surface 41c of the cylindrical portion 41 and the end surfaces 51a and 52a of the ribs 51 and 52.

[0028] Next, as shown in Figure 4(A), the welding horn 70 is pressed against the tip of the branched piece 42 and heated. As a result of the heating, as shown in Figure 4(B), the tip of the branched piece 42 melts, and an enlarged welding head 43 is formed. The welding head 43 is welded to the periphery of the arc-shaped hole 60 in the joining piece 32 and is also welded to the inner seating surface 32x. This forms a joint structure between the welding boss 40A and the joining piece 32.

[0029] In the welding head 43, not only the radially outer side but also the inner side of the welding boss 40A before welding is subjected to welding to the inner seating surface 32x. In other words, since not only the peripheral edge but also the central part of the welding head 43 is subjected to welding, the joint strength can be increased. Consequently, compared to the conventional technology, the length of the molten portion in the welding boss necessary to obtain joint strength can be shortened, and the welding time can be shortened.

[0030] Furthermore, the inner seating surface 32x prevents molten material from entering the inner base end side of the cylindrical portion 41 of the welded boss 40A. Consequently, it prevents adverse effects on the appearance of the design surface on the opposite side of the welded boss 40A on the upper trim body 31.

[0031] Furthermore, if the upper trim body 31 and the trim bracket 32 ​​are constructed from the same synthetic resin material, strong welding becomes possible due to the compatibility of the synthetic resins. As a result, the length of the molten portion of the welded boss can be made shorter.

[0032] According to the above embodiment, it is possible to provide a joining structure between the upper trim body 31 and the trim bracket 32 ​​that enhances the joining strength.

[0033] Next, other embodiments of the present invention will be described. In the following embodiments, only configurations that differ from the above embodiments will be described, and similar components will be denoted by the same reference numerals and their descriptions will be omitted.

[0034] [Second Embodiment] Figures 5 to 7 show a second embodiment of the present invention. In this embodiment, a sub-boss to be welded is provided on the inner seating surface 32x of the joining piece 32d.

[0035] As shown in Figures 5 and 6, a sub-boss 32y is integrally provided on the inner seating surface 32x of the joining piece 32, projecting in the direction of projection of the branched piece 42. The sub-boss 32y has a cylindrical shape, and its inner circumferential surface 32ya and outer circumferential surface 32yb are arranged concentrically with the inner arc surface 61 and outer arc surface 62 of the arc-shaped hole 60 in a plan view (see Figure 6(B)).

[0036] In this embodiment, the protruding height of the sub-boss 32y is set to be the same as the protruding height of the branch piece 42 from the connecting piece 32, but it may be set to be different.

[0037] In forming the joint structure with the joining piece 32 having the sub-boss 32y as described above, the welding horn 70 is brought into contact with the tip of the branched piece 42 protruding from the arc-shaped hole 60 of the joining piece 32d and the tip of the sub-boss 32y and heated, as shown in Figure 7(A). Upon heating, as shown in Figure 7(B), the tip of the branched piece 42 and the tip of the sub-boss 32y melt, forming an enlarged welding head 43 which is welded to the periphery of the arc-shaped hole 60, including the inner seating surface 32x.

[0038] According to the above embodiment, by providing a sub-boss 32y that is subjected to welding, the protruding portion of the arc-shaped hole 60 can be shortened, and the portion that contacts the welding horn 70 can be increased, thereby improving heating efficiency. Consequently, the welding time can be further shortened.

[0039] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be adopted without departing from the spirit of the invention. While a heating element was used for the welding horn 70, a device utilizing ultrasonic vibration or other methods may also be used. The number of branched portions 42 may be less than 3 or more than 3, and the arc-shaped holes 60 may be formed in accordance with the number of branched portions 42. In the second embodiment described above, the sub-boss 32y was formed in a hollow cylindrical shape, but it may also be formed in a solid cylindrical shape or other solid shapes. [Industrial applicability]

[0040] This invention can be applied to structures in which two synthetic resin components are joined by welding. [Explanation of symbols]

[0041] 10 Door trim 20 Roatrim 30 Upper Trim 31 Upper Trim Body (First Component) 32 Trim bracket (second component) 32a Upper wall part 32b Exterior wall 32c inner wall 32d joint piece 32x Inner seat 32y Sub-boss 32ya inner circumferential surface 32yb outer surface 40A, 40B Welding Boss 41 Cylindrical section 41a Inner surface 41b Outer surface 41c Tip surface 42 Branch section 42a Inner surface 42b External surface 43 Welding head 51, 52 Ribs 51a, 52a End faces on the outside of the vehicle interior 52b Wedge-shaped part 60 Arc-shaped hole (through hole) 61 Inner arc surface 63 Outer arc surface 70 Welded Horns S Weatherstrip

Claims

1. A joining structure for synthetic resin members comprising two members made of synthetic resin, wherein a hollow welding boss provided in the first member is inserted through a through hole formed in the second member, and the tip of the welding boss is welded to the periphery of the through hole, thereby joining the first member and the second member, The tip of the above-mentioned welded boss is divided into multiple branched sections in the circumferential direction. The through-holes are formed as a plurality of arc-shaped holes arranged circumferentially, corresponding to each of the plurality of branch pieces, and the portion of the second member surrounded by the plurality of arc-shaped holes forms the inner seating surface. A joining structure for synthetic resin members, characterized in that the welded head formed by the melting of the tip of the branched piece inserted into the arc-shaped hole is connected to the peripheral edge of the arc-shaped hole in the second member, the inner seating surface, and the plurality of branched pieces.

2. A joining structure for synthetic resin members comprising two members made of synthetic resin, wherein a hollow welding boss provided on the first member is inserted through a through hole formed in the second member, the tip of the welding boss is welded to the peripheral edge of the through hole, and the first member and the second member are joined together, The tip of the above-mentioned welded boss is divided into multiple branched sections in the circumferential direction. The through-holes are formed as a plurality of arc-shaped holes arranged circumferentially, corresponding to each of the plurality of branch pieces, and the portion of the second member surrounded by the plurality of arc-shaped holes forms the inner seating surface. The tip of the branched piece inserted into the arc-shaped hole is welded to the peripheral edge of the arc-shaped hole, including the inner seating surface. A joining structure for synthetic resin members, characterized in that a sub-boss is provided on the inner seating surface of the second member, which protrudes in the same direction as the protruding direction of the branched piece and is subject to welding.

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