Bonded structure

Abstract

To provide a structure of a bonded structure that can suppress peeling between a metal body and a resin body at a bonded plane.SOLUTION: A bonded structure 1 is constructed by bonding a resin body 20 onto a bonding plane 11 of a metal body 10. The bonded structure 1 has a composite rough surface in which areas 13 with high surface roughness and areas 14 with a surface roughness smaller than the roughness of the areas 13 with high surface roughness are alternately formed along the bonded plane 11, and the resin body 20 is bonded to the composite rough surface.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a joint structure in which a metal body and a resin body are joined at mutually opposing joining surfaces. [Background technology]

[0002] 2. Description of the Related Art For the purpose of reducing weight and cost, a composite body in which a metal body and a resin body are joined at opposing joining surfaces is known (see, for example, Patent Document 1). Patent Document 1 addresses the issue of improving the bonding strength between metal parts and resin parts, and specifies the structure of a groove to be formed by laser processing. After irradiating a laser from a direction perpendicular to the bonding surface of the metal part to form a vertical groove, the groove is filled with resin to improve the bonding strength with the resin part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5843750 Summary of the Invention [Problem to be solved by the invention]

[0004] As an example of this type of composite, an automobile part is being considered in which a reinforcing member (rib) made of carbon fiber reinforced thermoplastic resin (CFRTP) as a resin body is press-formed onto a metal body (metal sheet).These composite automobile parts are manufactured by integrally forming heated thermoplastic resin and a metal sheet in a mold.

[0005] However, in large parts such as those used in automobile bodies, the bonding area between the resin body and the metal body is large, so the difference in linear expansion between the materials has a greater effect. In other words, when the resin body and the metal body are integrally formed, the resin body is melted and integrated with the metal body, but due to the difference in linear expansion between the materials, large stress is generated at the joint interface between the resin body and the metal body, and this stress may cause peeling at the joint interface (especially the longitudinal ends of the parts).

[0006] Therefore, the present invention has been made with attention to such problems, and has an object to provide a joined structure in which a metal body and a resin body are joined at opposing joining surfaces, which can suppress peeling at the joining surface between the metal body and the resin body. [Means for solving the problem]

[0007] In order to solve the above problems, a joined structure according to one embodiment of the present invention is a joined structure in which a resin body is joined to a joining surface of a metal body, and has a composite rough surface in which areas of high surface roughness and areas of low surface roughness are alternately formed along the joining surface, and the resin body is joined to the composite rough surface. Effect of the Invention

[0008] According to the present invention, a composite rough surface is formed on the joining surface of a metal body, with areas of high surface roughness and areas of low surface roughness alternating, and a resin body is joined to this composite rough surface.The composite rough surface disperses the stress generated at the joining interface, thereby suppressing delamination at the joining surface between the metal body and the resin body. [Brief description of the drawings]

[0009] [Figure 1] 1A and 1B are explanatory diagrams of a bumper reinforcement which is one embodiment that employs a joint structure according to the present invention, in which FIG. 1A is a plan view, FIG. 1B is a surface seen from the resin body side of FIG. 1A, and FIG. 1C is a ZZ cross-sectional view of FIG. [Diagram 2] 2A to 2D are explanatory diagrams of configuration examples of a composite rough surface formed on a joint surface of the bumper beam (metal body) shown in FIG. 1. [Diagram 3]2A to 2D are explanatory views of a manufacturing method of the bumper reinforcement shown in FIG. 1, each of which is a schematic view of a ZZ cross section in FIG. [Figure 4] 5A and 5B are schematic explanatory views of the action and effect of a composite rough surface in a joint structure according to the present invention. [Diagram 5] 5A to 5D are explanatory views of modified examples of a composite rough surface in a joint structure according to the present invention. [Figure 6] 1A and 1B are explanatory diagrams of modified examples of the concave-convex region that constitutes the composite rough surface in the joint structure according to the present invention. [Figure 7] 1A and 1B are explanatory diagrams of an example of a groove shape forming a concave-convex region, in which FIG. 1A is a schematic diagram in a plan view, and FIG. 1B is an enlarged view of a cross section of a main part in the thickness direction of FIG. [Figure 8] 6A and 6B are explanatory views of another example of a groove shape forming a concave-convex region, in which FIG. 6A is a schematic view in plan view, and FIG. 6B is an enlarged view of a cross section of a main part in the thickness direction of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationship and ratio between thickness and planar dimensions are different from the actual ones, and the drawings include parts where the relationship and ratio of dimensions are different from each other. Furthermore, the embodiments described below are merely examples of devices and methods for embodying the technical ideas of the present invention, and the technical ideas of the present invention do not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0011] [Bumper reinforcement] First, a bumper reinforcement that is an embodiment that employs a joint structure according to the present invention will be described. As shown in FIG. 1, the bumper reinforcement 1 of this embodiment includes a bumper beam 10 which is a metal body extending in the vehicle width direction W, and a reinforcing portion 20 which is a resin body joined to a peripheral wall back surface 12 of the bumper beam 10.

[0012] The bumper beam 10 is a long member made of an aluminum alloy, and has mounting portions 18, 19 near both ends thereof for mounting to the vehicle body. Two bent portions 16, 17 are formed on the inner side in the vehicle width direction from the two mounting portions 18, 19. In this embodiment, a crash box (not shown) is attached to each mounting portion 18, 19, and the bumper beam 10 is attached to the vehicle body via the crash boxes.

[0013] The reinforcing part 20 is a reinforcing member made of resin and attached to the peripheral wall back surface 12 of the bumper beam 10 along the extending direction. As shown in FIG. 1C, the reinforcing part 20 is joined to the joining surface 11 provided in a predetermined range of the peripheral wall back surface 12 of the bumper beam 10 by injection molding along the extending direction of the bumper beam 10. The reinforcing part 20 of this embodiment is made of fiber reinforced thermoplastic resin (FRTP). In particular, the fibers of the fiber reinforced resin of this embodiment are discontinuous short fibers, and the fibers of the fiber reinforced resin are carbon fibers.

[0014] Here, as shown in Figure 2, the joining surface 11 of the peripheral wall back surface 12 of the bumper beam 10 has a composite rough surface in which areas 13 with high surface roughness and areas 14 with a surface roughness smaller than that of the areas 13 with high surface roughness are alternately formed along the joining surface 11.

[0015] In the joint surface 11 of this embodiment, as a composite rough surface, uneven regions 13, which are regions having fine irregularities, and smooth regions 14, which are smooth regions without irregularities, are alternately formed along the longitudinal direction X (vehicle width direction W) of the joint surface 11. In this embodiment, the uneven regions 13 are regions in which irregularities are formed along the joint surface by laser processing or the like. In contrast, the smooth regions 14 are untreated regions that have not been subjected to laser processing.

[0016] Furthermore, various configuration patterns can be adopted for the composite rough surface, as long as areas of high surface roughness 13 and areas of low surface roughness 14 are alternately formed along the joining surface 11, as exemplified in Figures (a) to (d). For example, as shown in Fig. 1(a), a lattice pattern (checkered pattern) can be adopted across the longitudinal direction X and the intersecting direction Y. Also, as shown in Fig. 1(b), a pattern can be adopted in which regions of the same area are arranged alternately along the longitudinal direction X (vehicle width direction W). Moreover, the area of ​​each of the large surface roughness regions 13 and the small surface roughness regions 14 and their arrangement can also be modified in various ways. For example, as shown in FIG. 1(c), the region 13 with high surface roughness can be composed of a set of multiple regions 13 with different areas, and these multiple regions 13 with different areas can be arranged diagonally along the joining surface 11 as shown in FIG. 1(c), and the area other than the region 13 with high surface roughness can be made into a region 14 with low surface roughness. Also, as shown in Fig. 1(d), for example, a configuration pattern can be adopted in which regions of different areas are arranged alternately along the longitudinal direction X (vehicle width direction W). Fig. 1(d) shows an example in which the region area is large near the center in the longitudinal direction X (vehicle width direction W) and becomes narrower toward both ends in the longitudinal direction X (vehicle width direction W).

[0017] [Manufacturing method for bumper reinforcement] Next, a manufacturing method of the bumper reinforcement 1 of the first embodiment will be described. The manufacturing process for the bumper reinforcement 1 in FIG. 1 begins with creating a hollow beam material along the extension direction by extruding an aluminum alloy material, and then machining the mounting portions 18, 19 for the crash boxes near both ends of this beam material.

[0018] Next, bending is performed at predetermined positions of the beam material to form the two bent portions 16 and 17. Next, as shown in Fig. 3(a), the composite rough surface is formed on the portion that will become the joint surface 11 that is connected to each joint portion 21 of the two reinforcing portions 20. That is, in this embodiment, in order to improve the joining strength between each of the joints 21 of the two reinforcing parts 20 and the joining surface 11, fine groove shapes that become the uneven regions 13 are formed in a predetermined configuration pattern by laser processing on the portion of the peripheral wall back surface 12 of the beam material that becomes the joining surface 11. At this time, the laser processing is performed so that the uneven regions 13 and the smooth regions 14 are formed alternately in the longitudinal direction X (vehicle width direction W) as the predetermined configuration pattern, as shown in Figs. 2(a) to (d).

[0019] Next, as shown in Figure 3(b), the peripheral wall back surface 12 of the bumper beam 10 is inserted and fixed into the storage portion of one of the first molds 71 ​​of the mold set 70 with the back surface 12 facing the second mold 72 so that only the respective joint portions 21 of the two reinforcing portions 20 are joined to the portion that will become the joint surface 11 of the bumper beam 10. Thereafter, a second mold 72 opposing the first mold 71 is clamped relatively from the side of the peripheral wall back surface 12 of the bumper beam 10. As a result, the mold set 70 is assembled so as to surround the bumper reinforcement 1, which is a joined structure that will become a molded product.

[0020] 3(c), molten resin (e.g., discontinuous fiber CFRTP) heated by an injection molding machine (not shown) is forced into the resin injection space of the mold set 70 by applying injection pressure from a molten resin supply passage (not shown), and the reinforcing part 20 is joined by injection molding. The molten resin supply passage (spool, runner, gate, etc.) and gas vent part can be disposed in appropriate positions.

[0021] After filling the resin into the resin injection space and cooling for a certain period of time, the bumper reinforcement (jointed structure) 1, in which the bumper beam (metal body) 10 and the reinforcing portion (resin body) 20 are integrated, is demolded and taken out from the mold set 70, as shown in FIG. 3(d). As a result, the bumper beam 10 is reinforced as desired by the reinforcing portion 20. Thereafter, crash boxes are attached to the mounting portions 18, 19 on both ends of the rear peripheral wall surface 12 of the bumper beam 10, and the bumper reinforcement 1 is completed.

[0022] The resin material to be bonded (covered) as the reinforcing part (resin body) 20 in the bonding process can be, for example, PA6 + 40 wt% carbon long fiber. Other materials may include thermoplastic resins such as various polyamides (PA66, MXD6, etc.), PPS, ABS, PP, PC, PBT, etc., carbon short fiber, glass fiber, and cellulose-based natural fiber. In addition, the bonding (covering) conditions by injection molding of the reinforcing part (resin body) 20 in the bonding process can be, for example, injection pressure: 117 MPa, mold temperature: 140°C, and injection screw temperature (resin temperature): 280°C.

[0023] [Effects] In the joined structure 1 of this embodiment, a composite rough surface is provided on the joining surface 11, in which regions 13 with high surface roughness and regions 14 with a surface roughness smaller than that of the regions 13 with high surface roughness are alternately formed along the longitudinal direction (W) of the joining surface 11, and a resin body 20 is joined to this composite rough surface. As a result, according to the joined structure 1 of this embodiment, the stress generated at the joint interface is dispersed by a composite rough surface in which areas of high surface roughness 13 and areas of low surface roughness 14 are alternately formed along the joining surface 11, as shown by the white arrows in Figure 4, which shows an image of the stress after resin is filled into the resin injection space and cooled for a certain period of time. In other words, as shown in the image of the same figure (a), if the bonding surface 11 is formed only from the area 13 with high surface roughness, the stress generated at the bonding interface will not be dispersed but will become large, and the stress will be concentrated at the longitudinal end of the bonded structure 1, causing peeling at the bonding surface 11 between the metal body 10 and the resin body 20. In contrast, by providing a composite rough surface on the joining surface 11 in which areas 14 having a smaller surface roughness than areas 13 having a larger surface roughness are alternately formed along the joining surface 11, as shown in the image in the same figure (b), the stress generated at the joining interface is dispersed and stress is less likely to concentrate at the ends in the longitudinal direction of the joined structure 1. This suppresses the effect of the difference in linear expansion coefficient between the materials, and thus prevents peeling at the joining interface [Invention 1].

[0024] In particular, in the joint structure 1 of this embodiment, as shown in Figure 2, the region 13 with high surface roughness is an uneven region consisting of an uneven surface in which multiple grooves are formed by laser irradiation L, and the region 14 with low surface roughness is a smooth region consisting of a smooth surface other than the uneven region. As a result, the joining structure 1 of this embodiment is suitable for efficiently providing alternating uneven regions 13 having fine irregularities and smooth regions 14 having no irregularities and are smooth, alternately along the joining surface 11, such as in the bumper reinforcement shown as an application example, by forming fine groove shapes in a predetermined structural pattern by laser processing on the joining surface 11 of the rear wall 12 of a long bumper beam 10 [Invention 2].

[0025] As shown in FIG. 1, the joint structure 1 of this embodiment is a bumper reinforcement that is attached along the vehicle width direction within the front or rear bumper of a vehicle body, the metal body 10 is a metal bumper beam having two mounting portions 18, 19 at both ends of its rear surface for mounting to the vehicle body, and the resin body 20 is a resin reinforcing portion that is joined along the rear surface of the bumper beam.

[0026] That is, according to the joint structure 1 of this embodiment, the joint structure 1 of this embodiment is adopted for bumper reinforcement. Therefore, as a structure for an automobile part, for example, it has a sufficient structure to satisfy the target adhesion force in the vertical direction, and is suitable as a joint structure that is excellent in appearance quality and can exhibit the required strength as a structure for an automobile part, in that it is lightweight and exhibits the required strength at low cost without the need for a modification process, etc. [Invention 8].

[0027] As described above, according to the bumper reinforcement (jointed structure) 1 of this embodiment, a composite rough surface is formed on the joint surface 11 of the metal body 10, with uneven areas 13 and smooth areas 14 being provided alternately, so that the stress generated at the joint interface is dispersed by the action of the composite rough surface, and peeling at the joint surface 11 between the metal body 10 and the resin body 20 can be suppressed. Note that the joint structure according to the present invention is not limited to the above embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention.

[0028] For example, as shown in Figure 5, another example of the configuration of a composite rough surface, on the joining surface 11 of the rear surface of the peripheral wall 12, the multiple uneven areas 13 can be arranged in a checkered houndstooth pattern with more stages (Figure 5(a)), a spiral pattern (Figure 5(b)), or a spaced lattice pattern (Figure 5(c)). As shown in Fig. 1(d), even in the grid-like arrangement, the aspect ratio between the first direction (X direction) and the second direction (Y direction) can be set appropriately. In Fig. 1(d), the first direction (X direction) corresponding to the longitudinal direction X (vehicle width direction W) is made shorter than the second direction (Y direction), and the arrangement pattern is such that the area in the longitudinal direction X (vehicle width direction W) is more finely dispersed.

[0029] In this way, the uneven regions 13 and the smooth regions 14 can be formed alternately in both the first direction (X direction) along the joining surface 11 and the second direction (Y direction) intersecting the first direction (X direction). As a result, the uneven regions 13 and the smooth regions 14 are arranged alternately in both the first direction (X direction) and the second direction (Y direction) intersecting therewith, so that the influence of the difference in linear expansion in both the first direction (X direction) and the second direction (Y direction) can be suppressed, and peeling at the interface can be suppressed [Invention 3].

[0030] Furthermore, FIG. 6 shows another example of a composite rough surface. In this example, as shown in Figure 1(a), uneven regions 13, which are regions having fine irregularities, and smooth regions 14, which are smooth regions without irregularities, are formed alternately on the joint surface 11 of the rear surface 12 of the peripheral wall of the bumper beam 10, and as shown in an enlarged view of the main part in Figure 1(b), a plurality of grooves 30 are formed in the uneven region 13 so that the number of grooves 30 per given area decreases as one approaches the center of the surface in the uneven region 13.

[0031] Here, in the uneven region 13, stress is more likely to concentrate at the edge of the surface than at the center of the surface. In other words, the applied stress decreases toward the center of the surface in the uneven region 13. And, since the uneven region 13 is formed by digging the joining surface 11 of the metal body 10 by irradiating it with a laser to form a large number of fine grooves 30, by decreasing the amount of fine groove shapes as it approaches the center of the surface in the uneven region 13, the amount of laser processing can be reduced in manufacturing, thereby shortening the processing time [Invention 4].

[0032] As shown in the above embodiment, the uneven region 13 is formed by digging the joining surface 11 of the metal body 10 with laser irradiation L to form fine groove shapes, and the depth D of the grooves 30 of the uneven region 13 on the joining surface 11 is preferably set to 10 μm to 250 μm as shown in Fig. 7. If the depth D of the grooves 30 is less than 10 μm, the joining strength with the resin body 20 may be insufficient, while if the depth D of the grooves 30 is more than 250 μm, the laser processing takes a long time [Invention 5].

[0033] In this embodiment, the uneven shape of the uneven region 13 is formed by a plurality of grooves 30, and as shown in Fig. 8, the plurality of grooves 30 are desirably formed at an angle (θ<90°) by laser irradiation L with respect to the joining surface 11 of the metal body 10. By providing an inclination (e.g., θ=70°) with respect to the joining surface 11 of the metal body 10, it is possible to obtain higher strength against pulling out in the joining direction between the metal body 10 and the resin body 20 [Invention 6].

[0034] Furthermore, in the bumper reinforcement 1 of this embodiment, as shown in Figs. 7 and 8, it is preferable that the surface 15 of the metal body 10 opposite the joining surface 11 to be joined to the resin body 20 is a smooth surface. This embodiment is particularly effective for large parts such as bumper reinforcement of an automobile, which are present on the surface of the automobile body. Therefore, it is a part that is related to the design of the automobile. Therefore, since the surface 15 opposite to the joint surface 11 with the resin body 20 is a smooth surface, it can be installed without affecting the design [Invention 7]. [Explanation of symbols]

[0035] 1 Bumper reinforcement (joint structure) 10 Bumper beam (metal body) 11 Joint surface 12 Rear side of surrounding wall 13 Uneven areas (areas with high surface roughness) 14 Smooth area (area with low surface roughness) 15 Surface opposite to the joining surface 16, 17 Bend 18, 19 Mounting part 20 Reinforcement part (resin body) 21 Joint 30 grooves 70 Mold set 71 The First Mold 72 Second Mold L Laser irradiation image W Vehicle width direction X Primary Direction Y Second direction

Claims

1. A joint structure in which a resin body is joined to a joint surface of a metal body, A composite rough surface is formed by alternating areas of high surface roughness and areas of low surface roughness along the joining surface, A bonded structure, characterized in that the resin body is bonded to the composite rough surface.

2. the region with high surface roughness is an uneven region having an uneven surface on which a plurality of grooves are formed, The bonded structure according to claim 1 , wherein the region with low surface roughness is a smooth region consisting of a smooth surface other than the uneven region.

3. The bonded structure according to claim 2 , wherein the uneven regions and the smooth regions are alternately formed in both a first direction along the bonded surfaces and a second direction intersecting the first direction.

4. The joint structure according to claim 2 , wherein the number of grooves per unit area of ​​the uneven region decreases toward the center of the joint surface.

5. The bonded structure according to claim 2 , wherein the depth of the grooves in the uneven region is 10 μm or more and 250 μm or less.

6. The joint structure according to claim 2 , wherein the grooves in the uneven region are formed obliquely with respect to the joint surface of the metal body.

7. The joined structure according to claim 1 , wherein the metal body has a smooth surface on the side opposite to the joining surface joined to the resin body.

8. The joining structure is a bumper reinforcement that is attached to a front or rear bumper of a vehicle body along a vehicle width direction, The metal body is a metal bumper beam having two mounting portions at both ends of its rear surface for mounting to a vehicle body, The joined structure according to any one of claims 1 to 7, wherein the resin body is a resin reinforcing part joined along the back surface of the bumper beam.

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