Composite and its manufacturing method

Abstract

To provide a composite body and its manufacturing method that can further improve the adhesion of mutually opposed bonding surfaces of a metal portion and a resin portion.SOLUTION: The composite 1 consists of a metal portion 10 and a resin portion 20 joined at mutually opposed bonding surfaces 11 and 21. The metal portion 10 has a first groove 30 formed along one direction on the bonding surface 11 of the metal portion 10, a second groove 40 formed along the other direction intersecting the first groove 30, a first bridging portion 50A formed to connect the two edges of the second groove 40 with each other by the metal base material of the metal portion 10 along the first groove 30 at at least a part of the intersection of the first groove 30 and the second groove 40, and a second bridging portion 50B formed to connect the two edges of the first groove 30 with each other by the metal base material of the metal portion 10 along the second groove 40 at at least a part of the intersection, and the bonding surfaces 21 of the resin portion 20 are joined with the resin matrix filling the interior of the first groove 30 and the second groove 40.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a composite body in which a metal part and a resin part are joined at opposing joining surfaces, and a method for producing the same. [Background technology]

[0002] A composite body in which a metal part and a resin part are joined at their opposing joining surfaces for the purpose of reducing weight and cost is known (see, for example, Patent Document 1). Patent Document 1 aims to improve the joining strength between the metal part and the resin part by specifying the structure of the groove formed by laser processing, and then filling the vertical groove formed by irradiating the laser from a direction perpendicular to the joining surface of the metal part with resin to improve the joining strength.

[0003] 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 part is press-formed on a metal part (metal sheet).These composite automobile parts are manufactured by integrally forming heated thermoplastic resin and a metal sheet in a mold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5843750 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the adhesiveness between the opposing joining surfaces of this type of composite cannot be maintained sufficiently, the composite cannot exhibit the strength required for the structure of an automobile part. In contrast, in the technology described in Patent Document 1, resin is filled into grooves formed on the metal surface. However, simply forming a vertical groove has the problem that the resin easily escapes from the groove when vertical tensile stress is applied, and there remains an issue that needs to be resolved in order to improve the joining strength.

[0006] The present invention has been made in light of these problems, and has an objective of providing a composite body that can further improve (improve adhesion) the adhesion (vertical tensile strength) of the mutually opposing joining surfaces of a metal part and a resin part, and a method for manufacturing the same. [Means for solving the problem]

[0007] In order to solve the above problems, a composite according to one embodiment of the present invention is a composite in which a metal part and a resin part are joined at mutually opposing joining surfaces, and the metal part has a first groove formed along one direction on the joining surface of the metal part, a second groove formed along another direction intersecting the first groove, and a first bridging portion formed so as to connect both edges of the first groove by the metal base material of the metal part along the second groove at at least a part of the intersection between the first groove and the second groove, and a second bridging portion formed so as to connect both edges of the second groove along the first groove at at least a part of the intersection between the first groove and the second groove, and the joining surface of the resin part is joined in a state in which the inside of the first groove and the second groove are filled with a resin base material.

[0008] In order to solve the above problems, a method for producing a composite according to one embodiment of the present invention is a method for producing a composite in which a metal part and a resin part are joined at mutually opposing joining surfaces, and includes an L-shaped groove forming step of forming an L-shaped groove in which a first groove along one direction and a second groove along another direction intersecting the first groove are successively opened on the joining surface of the metal part in the extension direction of the joining surface, and a joining step of integrally joining the joining surface of the resin part to the joining surface of the metal part in a mold while injecting and filling the inside of the L-shaped groove formed in the metal part in the L-shaped groove forming step, and forming a further continuous L-shaped groove by shifting it in the extension direction of the joining surface so as to overlap at least a part of the rectangular end of the corner of the already formed L-shaped groove, thereby forming an L-shaped bridge structure that connects both edges of the first and second grooves to each other by the metal base material of the metal part at the rectangular end of the overlapping corner.

[0009] In order to solve the above-mentioned problems, a manufacturing method of a composite according to another aspect of the present invention is a method for manufacturing a composite in which a metal part and a resin part are joined at mutually opposing joining surfaces, the method including a groove forming step of forming a plurality of grooves opening on the joining surface of the metal part, and a joining step of integrally joining the joining surface of the resin part to the joining surface of the metal part in a mold while injecting and filling the inside of the grooves formed in the metal part in the groove forming step, the groove forming step further including a first groove forming step of forming a first groove along one direction on the joining surface, and a second groove forming step of forming a second groove along another direction intersecting the one direction. the first groove forming step includes repeatedly forming the first groove so as to intersect with the second groove already formed, thereby forming a pair of first bridging portions that respectively connect both edges of the second groove by the metal base material of the metal part on both sides of the first groove at the intersection between the first groove and the second groove, and the second groove forming step includes forming the second groove so as to intersect with the first groove already formed, thereby forming a pair of second bridging portions that respectively connect both edges of the first groove by the metal base material of the metal part on both sides of the second groove at the intersection between the second groove and the first groove. Effect of the Invention

[0010] According to the present invention, the bonding strength of the mutually opposing bonding surfaces of the metal part and the resin part can be further improved. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram of a composite according to one embodiment of the present invention, in which FIG. 1(a) is a schematic perspective view of a portion thereof, and FIG. 1(b) is an enlarged view of a main portion of a bridge structure portion of a metal part in FIG. 1(a) (part indicated by symbol F in FIG. 1(a)). [Diagram 2] The figures are obtained by observation with an optical microscope, in which (a) is an enlarged cross-sectional view of the bridge portion of the first groove at the intersection of the first groove and the second groove, and (b) is an enlarged cross-sectional view of a location other than the intersection of the second groove. [Diagram 3]FIG. 2 is a schematic enlarged view of bridge portions on both edges of a groove at an intersection in a composite body according to one embodiment of the present invention. [Figure 4] FIG. 1 is a first embodiment of a composite according to an embodiment of the present invention and a method for producing the same, and the figure shows explanatory views (a) to (d) of a step of forming an L-shaped bridge structure that connects both edges of a groove at an intersection. [Diagram 5] FIG. 2 and FIG. 3 are second and third embodiments of a composite according to one embodiment of the present invention and a method for manufacturing the same, and are explanatory views (a) to (d) and (e) of other steps for forming a bridging portion connecting both edges of a groove. [Figure 6] FIG. 4 shows a fourth embodiment of a composite body and a manufacturing method thereof according to an embodiment of the present invention, in which (a) to (c) are explanatory views of other steps for forming bridge portions connecting both edges of a groove. [Figure 7] 1A and 1B are schematic explanatory diagrams of a bumper reinforcement according to an embodiment of the present invention, in which FIG. 1A is a plan view, FIG. 1B is a view of FIG. 1A from the rear side of the bumper beam, and FIG. 1C is an enlarged view of the ZZ cross section of FIG. [Figure 8] 1A to 1D are diagrams for explaining a manufacturing method of a bumper reinforcement according to an embodiment, and each diagram (a) to (d) is a schematic diagram showing a cross-sectional view of a bumper beam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 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 in which the relationship and ratio of dimensions are different from each other. In addition, the embodiments shown below are examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0013] [Complex] First, an embodiment of a composite body according to an embodiment of the present invention and an aspect of a metal part thereof will be described. 1, the metal part 10 is a metal plate (metal sheet) made of an aluminum alloy (e.g., A5052) having a thickness of about 1 mm. The metal part 10 of this embodiment has a vertical groove 30, which is a first groove that opens onto the joining surface 11 along the Y direction in the figure, and a horizontal groove 40, which is a second groove that opens onto the joining surface 11 along the X direction in the figure.

[0014] The vertical grooves 30 and the horizontal grooves 40 are formed to intersect with each other to form a lattice pattern. In the metal part 10 of this embodiment, the intersection angle (φ) between the vertical grooves 30 and the horizontal grooves 40 is, for example, 90 degrees (a right angle). In this example, the Y direction corresponds to one direction, and the X direction corresponds to another direction that intersects with the one direction.

[0015] In this embodiment, the longitudinal groove 30 and the lateral groove 40 are each formed of a plurality of grooves each opening on the joining surface 11 of the metal part 10. Each of the grooves 30, 40 is formed by pulse laser processing up to a position of a middle part in the thickness direction (Z direction) of the metal part 10 so as not to penetrate to the back side of the metal part 10. In the example of the same figure, the groove width of each groove formed by pulse laser processing is, for example, 60 μm for both the groove width W1 of the longitudinal groove 30 and the groove width W2 of the lateral groove 40. In addition, the groove depth d1 of the longitudinal groove 30 in the thickness direction Z is, for example, 100 μm, and the groove depth d2 of the lateral groove 40 in the thickness direction Z is, for example, 100 μm. However, when the lateral groove does not have a bridge portion in the embodiment, it is preferable that the groove depth d2 of the lateral groove 40 is equal to or greater than the groove depth d1 of the longitudinal groove 30.

[0016] Here, the metal part 10 has a bridging structure C at least in a part of the intersection with the longitudinal groove 30 and the lateral groove 40. The bridging structure C is formed by the metal base material of the metal part 10 in a groove processing step by laser processing described later. In the example shown in Fig. 1 and Fig. 2(a), the bridging structure C is configured to connect both upper edges of the longitudinal groove 30 to each other along the lateral groove 40, and is formed on both sides of the lateral groove 40 along the lateral groove 40 at the intersection.

[0017] Furthermore, the longitudinal grooves 30 or the lateral grooves 40 are preferably inclined grooves formed obliquely with respect to the joining surface 11 of the metal part 10. In this embodiment, as shown in Fig. 2(b) , by forming the lateral grooves 40 as inclined grooves, an undercut shape that forms an inverted triangle with respect to the metal part 10 is formed as a hook portion (anchor) 60 in each inclined groove of the lateral grooves 40. Note that it is more preferable that the longitudinal grooves 30 as well as the lateral grooves 40 are inclined grooves.

[0018] In this specification, the conditions of the test piece observed with an optical microscope were as follows: the metal part 10 was an A7000 series aluminum material (length 50 mm, width 10 mm, thickness 2 mm) whose width and thickness surfaces had been treated with a pulse laser. The groove structure was set so that the longitudinal grooves 30 were vertical grooves and the transverse grooves 40 were inclined grooves at an angle of 20°, with a depth of 100 μm, a groove width of 60 μm, and groove pitches p1 and p2 of 200 μm. The resin part 20 was made of carbon fiber reinforced thermoplastic resin (CFRTP, PA6 resin containing 40 wt% long carbon fiber: Plastron made by Polyplastics) (length 50 mm, width 10 mm, thickness 2 mm). (The test piece shape was in accordance with Type A of the ISO19095 resin-metal joint property evaluation test method, and the width and thickness surfaces were joined together.)

[0019] 2 and 3, in the composite body 1 of this embodiment, the joining surface 21 of the resin part 20 is joined to the joining surface 11 of the metal part 10 so as to fill the interiors of the vertical grooves 30 and the horizontal grooves 40 formed in the metal part 10. In the joining process of this embodiment, the joining surface 21 of the resin part 20 is joined integrally to the joining surface 11 of the metal part 10 in a mold, as will be described later.

[0020] [First embodiment of cross-linked structure] Various embodiments of the above-mentioned crosslinked structure C and a method for producing the same will be described below. 4, the bridging structure C of the first embodiment is configured such that a first bridging portion 50A connects both upper edge portions of the lateral groove 40 along the longitudinal groove 30, and a second bridging portion 50B connects both upper edge portions of the longitudinal groove 30 along the lateral groove 40. In the metal part 10 of this embodiment, the bridging structure C is L-shaped in that the first bridging portion 50A formed along the longitudinal groove 30 and the second bridging portion 50B formed along the lateral groove 40 are formed at positions where one end is adjacent to the intersection of the grooves 30, 40.

[0021] [Method of manufacturing the composite] Next, a method for producing the composite body 1 according to the first embodiment will be described. To manufacture the composite 1 according to this embodiment, an L-shaped groove is formed in the joining surface 11 of the metal part 10, in which a vertical groove 30 along one direction and a horizontal groove 40 along another direction intersecting the vertical groove 30 are continuous and each of the vertical grooves 30 opens on the joining surface 11, in the extending direction of the joining surface 11 (L-shaped groove forming process). In the composite 1 according to this embodiment, a thin plate material made of aluminum (A7000 series) is used as the metal part 10. However, other aluminum materials (e.g., A5000 series, A6000 series), steel, copper, brass, zinc, titanium, etc. can also be used as the metal part 10.

[0022] In the L-shaped groove forming process, first, as shown in Fig. 4(a), an L-shaped groove that continuously forms a vertical groove 30 and a horizontal groove 40 is formed from one corner of the joining surface 11 of the metal part 10 by pulse laser processing. Next, the irradiation position is shifted in the extension direction of the joining surface (XY direction) so that the rectangular ends of the corners of the already formed L-shaped groove overlap. 4(b) to 4(d), an L-shaped groove in which the vertical groove 30 and the horizontal groove 40 are continuous is formed in a zigzag shape by laser processing. In the L-shaped groove in which the vertical groove 30 and the horizontal groove 40 are continuously formed, the L-shaped groove is deepened by scanning multiple times (for example, six times) by pulse laser processing.

[0023] In this embodiment, the longitudinal grooves 30 are formed to have a groove width W1 of 60 μm and a groove depth d1 of 100 μm. The longitudinal grooves 30 and the lateral grooves 40 are formed as a plurality of L-shaped grooves such that the separation pitch P1 between the adjacent grooves 30 and 40 is, for example, 200 μm. By repeating this process, an L-shaped bridge structure C consisting of a first bridge portion 50A and a second bridge portion 50B is formed at the rectangular end of the corner of the L-shaped groove along the vertical groove 30 and the horizontal groove 40. Particularly, in the manufacturing method of the composite 1 of this embodiment, the peak intensity of the pulse laser is set to 100 to 1000 MW / cm2 for forming the bridge structure C, at which the metal base material of the metal part 10 melts and evaporates.

[0024] When forming an L-shaped groove on the joining surface 11 of the metal part 10 by connecting the vertical groove 30 and the horizontal groove 40, if the peak intensity of the pulsed laser irradiated to the joining surface 11 is set to about 100 to 1000 MW / cm2, at which the metal base material of the metal part 10 melts and evaporates as described above, the metal base material in the part irradiated with the pulsed laser melts and evaporates, forming a groove. In this embodiment, a groove having a depth of 100 μm is formed on the joining surface 11 by repeatedly irradiating a laser multiple times to dig an L-shaped groove in which the vertical groove 30 and the horizontal groove 40 are continuous. After digging the L-shaped groove in which the vertical groove 30 and the horizontal groove 40 are continuous, the rectangular ends of the corners of the L-shaped groove are shifted so as to overlap, and further, the L-shaped groove in which the vertical groove 30 and the horizontal groove 40 are continuous is formed in a zigzag shape.

[0025] As a result, the metal base material of the molten metal part 10 accumulates and rises at the upper edge of the L-shaped groove at the rectangular end of the corner of the L-shaped groove, and re-solidifies, so that an L-shaped bridging structure C consisting of a first bridging part 50A and a second bridging part 50B is formed from the metal base material. In the composite 1 of this embodiment, the L-shaped bridge structure C is formed by each of the bridge parts 50A and 50B, so that the L-shaped bridge structure C is formed across both the longitudinal groove 30 and the lateral groove 40, and therefore the tensile strength in the direction perpendicular to the bonding surfaces 11 and 21 can be increased compared to a bridge structure consisting of the first bridge part 50A or the second bridge part 50B alone. Note that, as the conditions for the pulse laser treatment, for example, a laser marker MD-F5200 manufactured by Keyence (wavelength: 1090 nm, output: 30 W to 50 W, pulse frequency: 60 kHz or more) can be used as the laser device.

[0026] Next, resin is filled into each of the vertical grooves 30 and horizontal grooves 40 formed in the metal part 10 in the above-mentioned L-shaped groove forming process, and the joining surface 21 of the resin part 20 is joined to the joining surface 11 of the metal part 10 so as to impregnate the resin into the gaps of each bridging part 50A, 50B that constitutes the bridging structure C (joining process).

[0027] [Second embodiment of cross-linked structure] Next, second and third embodiments of the bridge structure C formed by the first and second bridged portions 50A and 50B will be described with reference to FIG. 5(a) to 5(d), the second embodiment differs from the first embodiment in the positions at which the bridge portions 50A and 50B are formed on the joining surface 11. That is, in the second embodiment, the first bridge portions 50A are formed in pairs on both sides of the longitudinal groove 30 along the longitudinal groove 30 at the intersection, and the second bridge portions 50B are formed in pairs on both sides of the lateral groove 40 along the lateral groove 40 at the intersection.

[0028] In the groove forming process of the second embodiment, first, as shown in FIG. 5(a), a first vertical groove 30a is formed along the Y direction on the joining surface 11 of the metal part 10 by pulse laser processing (first groove forming process). The first longitudinal grooves 30a are formed by scanning each groove multiple times (e.g., six times) in the Y direction with a pulsed laser. In this embodiment, the first longitudinal grooves 30a are formed to have a groove width W1 of 60 μm and a groove depth d1 of 100 μm. The first longitudinal grooves 30a are formed in a plurality of stripes with a separation pitch P1 in the Y direction between adjacent longitudinal grooves 30a of, for example, 400 μm. The irradiation axis of the pulse laser can be oblique (for example, θ=20°). The grooves formed obliquely with respect to the joining surface 11 of the metal part 10 can form hooks (anchors) 60 for the resin part 20 filled inside the metal part 10 (see FIG. 2(b)).

[0029] Furthermore, as shown in FIG. 5(b), a first transverse groove 40a is formed along the X direction on the joint surface 11 of the metal part 10 by pulse laser processing (second groove forming step). In this embodiment, the scanning direction of the pulsed laser is the X direction, and the first transverse groove 40a is formed along the X direction. At this time, the irradiation axis of the pulsed laser is set obliquely (e.g., θ=20°), and a plurality of stripes are formed with a separation pitch P2 between adjacent transverse grooves 40a in the Y direction of, for example, 400 μm. The first transverse groove 40a is deepened by scanning multiple times (e.g., six times) in the X direction by pulsed laser processing. In this embodiment, the groove width W2 is targeted to be 60 μm, and the groove depth d2 is targeted to be 100 μm.

[0030] Here, in the groove forming step of the second embodiment, in order to form the bridging structure C, as shown in FIG. 5(b), in the second groove forming step, a first lateral groove 40a is formed so as to intersect with the already formed first longitudinal groove 30a, thereby forming a pair of second bridging portions 50B that respectively connect both edges of the first longitudinal groove 30a by the metal base material of the metal portion 10 on both sides of the first lateral groove 40a at the intersection between the first lateral groove 40a and the first longitudinal groove 30a.

[0031] Furthermore, in the groove forming step of the second embodiment, in order to form the bridge structure C, in the first groove forming step, as shown in Fig. 5(c), second longitudinal grooves 30b are formed so as to intersect with the already formed first transverse grooves 40a. In the example of the same figure, the second longitudinal grooves 30b are formed between the already formed first longitudinal grooves 30a in the same manner as in the first groove forming step. At this time, the second longitudinal grooves 30b are formed in a plurality of stripes with a separation pitch P1 in the Y direction between the adjacent first longitudinal grooves 30a (first longitudinal grooves 30a already formed) of, for example, 200 μm. As a result, at the intersections between the second longitudinal grooves 30b and the first lateral grooves 40a, a pair of first bridge portions 50A are formed by the metal base material of the metal portion 10 on both sides of the first lateral grooves 40a, respectively connecting both edges of the first lateral grooves 40a.

[0032] In the groove forming step of the second embodiment, the above procedure is repeated to form a pair of first bridged portions 50A and a pair of second bridged portions 50B in order to form a bridged structure C. That is, in the example shown in Fig. 5, second transverse grooves 40b are then formed between the already formed first transverse grooves 40a in the same manner as in the first groove forming step, as shown in Fig. 5(d). At this time, the second transverse grooves 40b are formed in a plurality of stripes with a separation pitch P2 between adjacent first transverse grooves 40a in the Y direction of, for example, 200 μm.

[0033] As a result, in the manufacturing method of the composite 1 according to the second embodiment, the first and second longitudinal grooves 30a, 30b and the first and second lateral grooves 40a, 40b can be formed in multiple stripes on the joining surface 11 of the metal part 10 by such a multiple-stage pulsed laser irradiation procedure. At the same time, as the bridge structure C, a pair of first bridge portions 50A on both sides of the second groove 40 along the first groove 30, and a pair of second bridge portions 50B on both sides of the first groove 30 along the second groove 40 can be formed at the intersection.

[0034] In the manufacturing method of the composite 1 according to the second embodiment, a cross-linking structure row C1 in which a pair of first cross-linking portions 50A and a pair of second cross-linking portions 50B are alternately formed at intersections adjacent to each other in the Y direction, and a cross-linking structure row C2 in which only the second cross-linking portions 50B are formed are repeatedly formed as the cross-linking structure C. In particular, in the manufacturing method of the composite 1 of the present embodiment, the peak intensity of the pulsed laser is set to 100 to 1000 MW / cm2, at which melting and evaporation occur in the metal base material of the metal portion 10, as the conditions for the laser treatment to form the cross-linking structure C.

[0035] Here, when the first groove 30 and the second groove 40 are formed on the joining surface 11 of the metal part 10, the peak intensity of the pulse laser irradiated onto the joining surface 11 can be set in the same manner as in the above-described first embodiment.

[0036] In the second embodiment, the first groove 30 and the second groove 40 are formed on the joining surface 11 with a depth of 100 μm by repeatedly irradiating the laser multiple times. In this case, the second groove 40a is dug after the first groove 30a, and then the first groove 30b is dug and then the second groove 40b is dug. As a result, the molten metal base material of the metal portion 10 accumulates and bulges on the upper edge portions of both the left and right walls of the second groove 40 along the first groove 30 and resolidifies to form a first bridge portion C made of the metal base material. Also, the molten metal base material of the metal portion 10 accumulates and bulges on the upper edge portions of both the left and right walls of the first groove 30 along the second groove 40 and resolidifies to form a second bridge portion C made of the metal base material. In this manner, in the composite 1 of the second embodiment, by forming a first cross-linking portion A and a second cross-linking portion B as the cross-linked structure C, cross-linking portions are formed in both the first groove 30 and the second groove 40, so that the tensile strength in the direction perpendicular to the joining surfaces 11, 21 can be increased.

[0037] Next, as described below, resin is filled into each of the grooves, the first groove 30 and the second groove 40, formed in the metal part 10 in the groove forming process, and the joining surface 21 of the resin part 20 is joined to the joining surface 11 of the metal part 10 so as to impregnate the voids of each bridging part 50 forming the bridging structure B with resin (joining process).

[0038] [Third embodiment of bridge structure] Next, a third embodiment of the bridge structure (FIGS. 5(a) to (e)) will be described with reference to FIG. 5(e). In the third embodiment, the arrangement pattern of the first bridge portion 50A and the second bridge portion 50B is different from that of the second embodiment. As shown in the figure, the arrangement pattern of the bridge portion 50 in the third embodiment is composed of only the above-mentioned row C3 (C1), and is different from that of the second embodiment in that a pair of the first bridge portion 50A and a pair of the second bridge portion 50B are alternately arranged at adjacent intersections.

[0039] In the groove formation process of the third embodiment, after forming the groove in Figure 5 (d) in the second embodiment, as shown by the hatched image in Figure 5 (e), a third vertical groove 30c is partially formed along the groove in a direction intersecting the crosslinking direction of the second bridging portion 50B already formed, thereby replacing the second bridging portion 50B and forming a pair of bridging portions 50A on both sides of the third vertical groove 30c in a direction intersecting the crosslinking direction of the second bridging portion 50B.

[0040] In the composite body 1 of the third embodiment, by forming a bridge structure C including a first bridge portion 50A and a second bridge portion 50B, the bridge structure C is formed by rows C3 in both the first groove 30 and the second groove 40, and the tensile strength in the direction perpendicular to the bonding surfaces 11, 21 can be increased. In particular, with the bridge structure C only by rows C3, a pair of bridge portions 50A and a pair of bridge portions 50B are alternately present at all intersections, so that the bonding strength can be kept uniform.

[0041] [Fourth embodiment of bridge structure] Next, a fourth embodiment of the bridging structure C will be described with reference to FIG. The fourth embodiment differs from the above-mentioned embodiments in that it further includes a third groove forming step of forming a third groove 35 that intersects obliquely from a different direction in addition to the first groove 30 and the second groove 40. According to the fourth embodiment, the first, second and third grooves 30, 40, 35 are arranged in a lattice pattern on the joining surface 11, so that pairs of bridge portions can be formed in a well-balanced manner at all intersecting portions.

[0042] That is, in the fourth embodiment, first, the first groove 30 is formed obliquely in the vertical direction as shown in Fig. 1(a). Next, the second groove 40 is formed in the horizontal direction as shown in Fig. 1(b), and then, the third groove 35 is formed so as to be inclined in the vertical direction opposite to the first groove 30 as shown in Fig. 1(c). In the example shown in Fig. 1, the interior angle of the intersection of the first, second and third grooves 30, 40, 35 is set to 60 degrees, and they are arranged so as to form a uniform lattice on the joining surface 11.

[0043] In the composite 1 of the fourth embodiment, a pair of bridges 50B, 50C is also formed at each intersection. This allows the bridges 50B, 50C to be formed as a bridge structure in both the first, second, and third grooves 30, 40, 35, and increases the tensile strength in the direction perpendicular to the bonding surfaces 11, 21. In particular, in the bridge structure of the fourth embodiment, the presence of a pair of bridges 50B, 50C at all intersections in a uniform lattice arrangement makes it possible to maintain uniform bonding strength.

[0044] [Bumper reinforcement] Next, an example of the complex 1 will be described with reference to FIG. This example is an example in which the composite 1 according to the present embodiment described above is applied to a bumper reinforcement, which is an automobile part. The bumper reinforcement is a collision-resistant part that is attached inside the front and rear bumpers of an automobile vehicle and absorbs impact during a collision to reduce damage to passengers. In this embodiment, in this type of bumper reinforcement, a resin reinforcement part is joined along the back surface of the metal bumper beam of the bumper reinforcement in order to reduce the weight of the vehicle body while ensuring the collision resistance performance during a vehicle collision. This allows the bumper beam to be effectively reinforced by resin joining. In this embodiment, the bumper beam corresponds to the metal part 10 and the reinforcement part corresponds to the resin part 20, so that the parts corresponding to the composite body 1 of the above embodiment will be described below with the same reference numerals.

[0045] As shown in Fig. 7, the bumper reinforcement 1 of this embodiment includes a metal bumper beam 10 extending in the vehicle width direction W, and a resin reinforcing portion 20 joined to the back surface 12 of the bumper beam 10. The bumper beam 10 has mounting portions 18, 19 for mounting to the vehicle body side near both ends thereof. Two bent portions 16, 17 are formed on the inner side of the two mounting portions 18, 19 in the vehicle width direction. This embodiment illustrates an embodiment in which a crash box (not shown) is attached to each mounting portion 18, 19, and the bumper beam 10 is mounted to the vehicle body side via the crash boxes.

[0046] The bumper beam 10 is a long member made of an aluminum alloy, and as shown in Fig. 7(c), the cross section is formed by extrusion molding into a generally rectangular shape, and the hollow structure is formed along the extension direction of the bumper beam 10. The reinforcing part 20 is made of resin, and is joined to the back surface 12 of the bumper beam 10 by injection molding along the extension direction of the bumper beam 10. The reinforcing portion 20 is a reinforcing member made of resin and attached along the extending direction of the back surface 12 of the bumper beam 10. In this embodiment, the reinforcing portion 20 is provided at two locations spaced apart above and below the bumper beam 10. The reinforcing portion 20 in this embodiment is made of carbon fiber reinforced thermoplastic resin (CFRTP).

[0047] [Manufacturing method for bumper reinforcement] Next, a manufacturing method for the bumper reinforcement 1 of this embodiment will be described with reference to FIG. The manufacturing process of the bumper reinforcement 1 begins with creating a hollow beam material along the extension direction by extruding an aluminum alloy material, and machining the mounting portions 18, 19 for the crash boxes near both ends of this beam material. Next, bending is performed at predetermined positions of the beam material to form the two bent portions 16, 17.

[0048] Next, as shown in Figure 8(a), in order to improve the bonding strength of the two bonding parts 21 of the reinforcing part 20, a base surface treatment is performed in which a fine groove shape is formed by laser processing on the part that will become the bonding surface 11 on the beam material side in the same manner as in the manufacturing method of the composite 1 of the above embodiment shown in Figures 4 to 6 (groove formation process).

[0049] 8(b) to (c), the bumper beam 10 is inserted into and fixed in one die 71 of the die set 70 so that only the two joints 21 are joined to the portion that will become the joint surface 11 of the bumper beam 10. Thereafter, the other opposing die 72 is clamped from the side of the back surface 12 of the bumper beam 10, and heated molten resin (e.g., CFRTP) is injected into the die by an injection molding machine (not shown), thereby performing resin injection molding to join the reinforcing portion 20 (joining process). 8(d), the mold is removed to take out the composite body in which the metal part 10 and the resin part 20 are integrated. This makes it possible to provide the desired reinforcement to the extrusion-molded bumper beam 10 by the reinforcing part 20.

[0050] The resin material to be bonded (coated) as the resin part 20 in the bonding process may be, for example, PA6 resin (CFRTP) containing 40 wt% long carbon fiber. In addition, various polyamides (PA66, MXD6, etc.), thermoplastic resins such as PPS, ABS, PP, PC, PBT, etc., carbon short fiber, glass fiber, or cellulose-based natural fiber may be used. Thermosetting resins such as epoxy may also be used if the manufacturing method is changed. In addition, the bonding (coating) conditions by injection molding of the resin part 20 in the bonding process may be, for example, injection pressure: 117 MPa, mold temperature: 140°C, and injection screw temperature (resin temperature): 280°C. As a result, the resin part 20 is integrated in a state where it fills the insides of the multiple grooves 30, 40 formed in the metal part 10. Hereinafter, the resin filled in the multiple grooves 30, 40 is also referred to as the filled resin 22. In addition, the resin impregnated in the voids of the metal bridge structure C is also referred to as the impregnated resin 23 (see FIG. 3).

[0051] [Effects] Next, the effects of the composite 1 and the manufacturing method thereof according to the above-mentioned embodiment and example will be described. In conventional composites, in order to improve the adhesion (vertical tensile strength) of the joint surface, vertical grooves perpendicular to the surface and horizontal grooves perpendicular to the surface are alternately crossed to form a lattice pattern on the joint surface of the metal part. However, if the adhesion between the metal part and the resin part cannot be sufficiently maintained, the strength required for the structure of an automobile part, for example, cannot be exhibited. Therefore, with such a conventional configuration, there is still room for improvement in the adhesion (improvement of adhesion) of the joint surface between the metal part and the resin part, which have low tensile strength in the vertical direction.

[0052] On the other hand, to improve the frictional force on the groove wall surface, the frictional force can be increased by deepening the groove depth of the lateral and longitudinal grooves, but this will also increase the laser processing time. The same is true for measures such as narrowing the groove spacing and increasing the number of grooves. Furthermore, simply deepening the groove depth is naturally limited by the limitations of the plate thickness of the metal part. In response to these problems, in the composite 1 and its manufacturing method of the present embodiment, as shown in Figures 1 and 4, a bridging structure C is formed along the first groove 30 and the second groove 40 at least at a portion of the intersection between the first groove 30 and the second groove 40 by the metal base material of the metal part 10 so as to connect both edges of the second groove 40 and the first groove 30 to each other along the first groove 30 and the second groove 40.

[0053] In the manufacturing method of the composite 1 of this embodiment, in the groove forming step, the first groove 30 is formed by laser processing, and then the second groove 40 is formed by laser processing, thereby forming a bridge structure C so as to connect both edges of the first groove 30. Then, in the joining step, the metal part 10 and the resin part 20 are joined at the mutually opposing joining surfaces 11, 21 while filling the first groove 30 and the second groove 40 with molten resin. For this reason, when the second groove 40 is formed, a portion covered with the melted and resolidified metal base material (i.e., bridge structure C) is formed on the first groove 30 on both sides of the portion intersecting with the first groove 30. When bridge structure C is formed by the metal base material, the resin is caught when tensile stress acts on the joint surfaces 11, 21 of the metal-resin composite 1, and therefore the joint strength can be improved.

[0054] Furthermore, the bridge structure C formed by the laser processing and resolidified metal base material becomes a porous structure. Since the bridge structure C portion has a porous structure, the molten resin can enter the bridge structure C portion as the impregnated resin 23. Therefore, when the first groove 30 and the second groove 40 are filled with the molten resin, the molten resin impregnates the voids of the bridge structure C and is firmly integrated with the bridge structure C as the impregnated resin 23, thereby obtaining a stronger bonded state. This can further improve the bond strength (the effect of improving the bond strength due to the porous structure of the bridge structure). Therefore, compared to a conventional configuration having only vertical grooves, the bonding strength improving effect of cross-linking structure C can further improve the resistance to peeling at the bonding surfaces 11, 21 in the resin-metal composite 1 when pulled in the vertical direction (further improving the tensile strength in the vertical direction).

[0055] In addition, according to the composite 1 of this embodiment, the crosslinked structure C is formed on both sides of the second groove 40 along the second groove 40 at the intersection of the grooves as in the example shown in Fig. 1, so that the resin filled under the pair of adjacent crosslinks is made even more difficult to escape by the so-called double-supported crosslinked structure C by the pair of adjacent crosslinks. Therefore, it is more suitable for suppressing or preventing the resin from escaping from the groove when a vertical tensile stress is applied.

[0056] In particular, according to the composite 1 of the first embodiment, as shown in FIG. 4, in addition to the above-mentioned first cross-linking portion 50A, the cross-linked structure C further includes a second cross-linking portion 50B formed along the first groove 30 at at least a portion of the intersection between the first groove 30 and the second groove 40 so as to connect both edges of the second groove 40, which is suitable for further improving the resistance to peeling at the bonding surfaces 11, 21 (further improving the tensile strength in the vertical direction) [Invention 1].

[0057] Here, when providing the first bridge portion 50A and the second bridge portion 50B, various arrangements can be adopted with respect to the mutual arrangement relationship of the first and second bridge portions 50A and 50B. For example, as shown in Fig. 4, the first bridge portion 50A and the second bridge portion 50B can be formed so as to have an L-shaped bridge structure C in a continuous manner. In the composite body 1 according to the first embodiment, an L-shaped bridge structure C is formed across both the longitudinal grooves 30 and the lateral grooves 40, so that the tensile strength in the direction perpendicular to the bonding surfaces 11, 21 can be increased compared to a bridge structure consisting of only the first bridge portion 50A or the second bridge portion 50B. [Invention 2]

[0058] 4, the first crosslinked portion 50A and the second crosslinked portion 50B can be formed to be spaced apart in an L-shape. In this case, it is preferable that the distance between the crosslinked portions including the L-shape bend (the distance between the first crosslinked portion 50A and the adjacent second crosslinked portion 50B) is 2p-w (the pitch p and the groove width w of the multiple first grooves 30 and the multiple second grooves 40 are the same). In the case of the composite 1 of the first embodiment, by forming the first cross-linked portion A and the second cross-linked portion B at a distance from each other as the cross-linked structure C, cross-linked portions are formed in both the first groove 30 and the second groove 40, thereby increasing the tensile strength in the direction perpendicular to the bonding surfaces 11, 21 [Invention 3].

[0059] 5, the first bridged portions 50A can be formed in pairs along both sides of the second groove 40, and the second bridged portions 50B can be formed in pairs along both sides of the first groove 30. With this configuration, bridged portions are formed in both the first groove 30 and the second groove 40, which is suitable for increasing the tensile strength in the direction perpendicular to the bonding surfaces 11, 21 [Invention 4].

[0060] In this case, it is preferable that the interval between adjacent bridges is 2p-w or less (the pitch p and the groove width w of the first grooves and the second grooves are the same). This configuration is suitable for increasing the tensile strength in the direction perpendicular to the joining surfaces 11 and 21, as in [Invention 3] [Invention 5].

[0061] In this case, it is preferable that a pair of first crosslinking portions 50A and a pair of second crosslinking portions 50B are alternately formed at another crosslinking portion adjacent to the crosslinking portion, as shown in Fig. 5(d) and (e) of the composite body 1 of the second and third embodiments. Such a configuration is suitable for increasing the tensile strength in the direction perpendicular to the joining surfaces 11 and 21 [Invention 6].

[0062] 6, the composite 1 according to this embodiment has a first crosslinking portion 50A and a pair of third crosslinking portions 50C formed at the intersections of the first groove 30 and the second groove 40 along the third groove 30c, and it is preferable that the distance between the first crosslinking portion 50A or the third crosslinking portion 50C and another crosslinking portion adjacent thereto is 2p-w or less (the pitch p and the groove width w of the multiple first grooves and the multiple second grooves are the same). With this configuration, it is preferable to increase the tensile strength in the direction perpendicular to the joining surfaces 11 and 21 [Invention 7], as with [Invention 3] and [Invention 5].

[0063] Here, the inventors of the present application have focused on the fact that, in addition to the effect of improving adhesion due to the cross-linked structure C, in this type of composite, frictional force at the groove wall surface at and near the joining surface 11 of the metal part 10 acts predominantly when the joining surfaces 11, 21 are pulled in the vertical direction. In other words, the inventors have found that, at present, the joining strength due to this frictional force is insufficient against the vertical force F, and that by increasing this, the adhesion (vertical tensile strength) of the joining surfaces 11, 21 can be further improved (improved adhesion).

[0064] That is, according to the composite body 1 of this embodiment, as shown in Fig. 2, Fig. 3 and Fig. 6, the second groove 40 is formed at an angle to the joining surface 11 of the metal part 10, so that the anchor effect of the hook part (anchor) 60 forming an inverted triangular shape with respect to the metal part 10 makes it more difficult for the resin filled under the cross-linked structure C to come out. Therefore, it is more suitable for suppressing or preventing the resin from coming out of the groove when a vertical tensile stress is applied [Invention 8], [Invention 9].

[0065] As a result, in addition to the bridging structure C, a hooking structure is formed by the obliquely formed second groove 40, which further exerts the anchoring effect of the hooking portion (anchor) 60, thereby further improving the joining strength. Also, as a structural effect of the obliquely formed second groove 40, as shown in Fig. 3, the amount of resin filled obliquely below the formed bridging structure C increases, so that the loss of the resin filled below the bridging structure C by the metal base material during tensile stress is further suppressed, thereby further improving the joining strength.

[0066] Furthermore, as a manufacturing effect of slanting the second groove 40 formed later, when the joining surface 11 is viewed from above, if the second groove 40 is formed at an angle, the position of the upper opening of the second groove 40 and the bottom of the second groove 40 are misaligned with respect to the opening of the first groove 30, so that the metal base material evaporated during laser irradiation is less likely to dissipate to the outside from the upper opening of the second groove 40. Therefore, the proportion of the metal base material used to form the bridge portion 50 can be increased.

[0067] According to the composite 1 of this embodiment, as shown in FIG. 1, the first grooves 30 are formed in a plurality of stripes along one direction, and the second grooves 40 are formed in a plurality of stripes along the other direction. In the second embodiment (FIG. 5(d)), the first grooves 30 have bridged portions, while some of the second grooves 40 do not have bridged portions. In this case, the pitch of the first grooves 30 can be made shorter than the pitch of the second grooves 40. This makes the number density of the first grooves 30 greater than the number density of the second grooves 40. Increasing the proportion of the first grooves 30 increases the proportion of the resin remaining, thereby further improving the bonding strength.

[0068] In addition, according to the composite 1 according to this embodiment, the groove depth of the second groove 40 can be set to be equal to or greater than the groove depth of the first groove 30. That is, assuming that the cross-sectional area S of the bridge portion 50 is formed with a width w / 2 and a depth d / 2 as shown in FIG. 2(a) with the groove width W and the groove depth d, S=W / 2×d / 2. Therefore, in FIG. 1(b), if the groove depth of the second groove 40 is made deeper than the groove depth of the first groove 30, the cross-sectional area of ​​the bridge structure C formed on the upper edge of the first groove 30 can be increased. Therefore, the strength of the bridge structure C is further improved, which is more suitable for suppressing or preventing the bridge structure C from being broken and the filling resin 22 from falling out of the first groove 30 when a vertical tensile stress is applied [Invention 10].

[0069] In addition, the first groove 30 has a catch due to the cross-linked structure C, whereas the second groove 40 does not have this catch, and therefore the pull-out strength of the second groove 40 is determined by catches due to minute irregularities on the side walls of the other grooves. Therefore, making the second groove 40 deeper than the groove depth of the first groove 30 is also suitable for increasing the pull-out strength of the second groove 40 itself.

[0070] 1, it is desirable that the strength f1 of the cross-linked structure C and the strength f2, which is the sum of the pull-out strength of the resin part 20 acting with the pair of cross-linking parts 50A formed on both sides of the second groove 40 as fulcrums and the hooking strength of the groove side surfaces, be equal to or greater than the strength of the resin matrix of the resin part 20. Ensuring that f1 and f2 are equal to or greater than the resin matrix strength f3 is more suitable for suppressing or preventing the filling resin 22 from coming out of the groove when a vertical tensile stress is applied.

[0071] In other words, the tensile strength in the vertical direction due to the crosslinked structure C is [strength of the resin base material x proportion of the non-intersecting portions of the first grooves]. The smaller the groove pitch of the first grooves 30 and the higher the number density, the higher this proportion becomes, and therefore the tensile strength in the vertical direction improves. As an example of an estimate for the strength of the resin matrix to be equal to or greater than f3, let f1 be the strength of bridge portion 50A, f2 be the pull-out strength of the resin portion between the bridge portions, f3 be the strength of the resin matrix, A1 = w × (w / 2) (w is W1 in FIG. 1(b)) be the area of ​​bridge portion 50 in the plan view direction, S be the cross-sectional area of ​​the bridge portion, A2 = L × w be the tensile area of ​​the resin portion between the bridge portions, σAL be the shear strength of aluminum, and σR be the shear strength of the resin (= f3), then

[0072] As f1, f1=σAL×(2×S) / A1=(σAL×d) / w>σR Rearranging the above equation, d>(σR×w) / σAL In this formula, the shear strength of A7000 series aluminum is set to 176 N / mm2, and since the cross-linked portion 50A has a porous structure, it is assumed to be 1 / 5 of this strength. If the 80°C shear strength of PA6 resin is 40 N / mm2 and the groove width w is 60 μm, the groove depth d can be estimated as d>70 μm.

[0073] As f2, f2=(((4×σR×w×d^2) / (3×L))+2×α×d×L) / A2 Here, the first numerator term of f2 assumes a uniformly distributed load of the beam with the bridge portion 50A as the fulcrum, and the second term assumes the catching force of the groove side surface. Substituting A2, f2=(4×σR×d^2) / (3×L^2)+2×α×d / w>σR In the above equation, if we assume that α = 0, then L < √(4d / 3) Therefore, since the width of the bridged portion is assumed to be w / 2, the spacing between the bridged portions is L+w / 2, and when d=100 μm and w=60 μm, the spacing between the bridged portions can be estimated as L+w / 2<150 μm.

[0074] When these formulas for f1 and f2 are satisfied, both f1 and f2 of the first groove 30 become equal to or greater than the resin base material strength f3, so that the resin base material above the groove breaks and the resin remains in the first groove 30. However, although α in the second term of f2 was assumed to be α=0, it is not actually 0. Therefore, in the composite 1 according to this embodiment, the condition that the resin does not come out can be substantially satisfied by setting the interval (hook length) L+w / 2 between adjacent crosslinked parts to “2p-w” that is equal to or greater than (√(4d / 3))+w / 2.

[0075] Furthermore, according to an example of the composite 1 of this embodiment, as shown in FIG. 7, the composite 1 is a bumper reinforcement that is attached along the vehicle width direction inside the front or rear bumper of the vehicle body, the metal part 10 is a metal bumper beam having two mounting parts at both ends of its back surface for mounting to the vehicle body side, and the resin part 20 is a resin reinforcing part that is joined along the back surface of the bumper beam. That is, according to this embodiment, the composite 1 according to this embodiment is used for bumper reinforcement. Therefore, for example, as a structure of an automobile part, it has a sufficient structure to satisfy the target vertical adhesion force in order to exert the necessary strength at a light weight and low cost, and is suitable as a composite that can exert the necessary strength as a structure of an automobile part [Invention 11].

[0076] In addition, in the manufacturing method of the composite 1 according to the first embodiment, as shown in FIG. 4, in the L-shaped groove forming process, a further continuous L-shaped groove is formed by shifting it in the extension direction of the joining surface 11 so as to overlap at least a portion of the rectangular end of the corner of the already formed L-shaped groove, thereby forming an L-shaped bridging structure C that connects both edges of the first and second grooves 30, 40 to each other at the rectangular end of the overlapping corner by the metal base material of the metal part 10. As a result, according to the manufacturing method of the composite 1 of the first embodiment, it is possible to form an L-shaped bridge structure C that connects both edges of the first and second grooves 30, 40, which is preferable for further improving the bonding strength [Invention 12].

[0077] Furthermore, according to the manufacturing method of the composite 1 of the second embodiment, as shown in Figures 5(a) to (d), the groove formation process includes a first groove formation process of forming a first groove 30 along one direction on the joining surface 11, and a second groove formation process of forming a second groove 40 along another direction intersecting the one direction. In the first groove formation process, the first groove 30 is formed so as to intersect with the second groove 40 that has already been formed, thereby forming a pair of first bridging portions 50A that connect both edges of the second groove 40 to each other on both sides of the first groove 30 at the intersection between the first groove 30 and the second groove 40 by the metal base material of the metal portion 10. In the second groove forming process, a second groove 40 is formed so as to intersect with the already formed first groove 30, and a pair of second bridging portions 50B are formed on both sides of the second groove 40 at the intersection between the second groove 40 and the first groove 30 by the metal base material of the metal portion 10, respectively connecting both edges of the first groove 30 to each other. As a result, according to the manufacturing method of the composite body 1 according to the second embodiment, a bridged structure C consisting of a pair of first crosslinking portions 50A or a pair of second crosslinking portions 50B can be formed on both sides of all the intersections between the first groove 30 and the second groove 40. This is therefore suitable for further improving the bonding strength [Invention 13].

[0078] Furthermore, according to the manufacturing method of the composite 1 of the third embodiment, as shown in FIG. 5(e), the groove formation process further includes a replacement process in which an additional groove is formed along the groove in a direction intersecting the crosslinking direction of the crosslinking portion that has already been formed, thereby replacing the crosslinking portion and forming a pair of crosslinking portions on both sides of the groove in the direction intersecting the crosslinking direction of the crosslinking portion. As a result, according to the manufacturing method of the composite 1 of the third embodiment, pairs of cross-linking parts are uniformly arranged, and a pair of cross-linking parts is present at every intersection, which makes it possible to maintain a uniform bonding strength, and is therefore suitable for further improving the bonding strength [Invention 14].

[0079] Furthermore, according to the manufacturing method of the composite 1 of the fourth embodiment, as shown in FIG. 6, the groove formation process further includes a first groove formation process of forming a first groove 30 along one direction on the joining surface, a second groove formation process of forming a second groove 40 along another direction intersecting the first direction, and a third groove formation process of forming a third groove 35 along yet another direction intersecting the one direction and the other direction. By arranging the first, second and third grooves 30, 40, 35 in a lattice pattern on the joining surface 11, a pair of bridging portions are formed on both sides of the grooves at all intersections, each connecting both edges of the groove by the metal base material of the metal portion 10. As a result, according to the manufacturing method for composite body 1 according to the fourth embodiment, by forming a pair of bridge parts at each intersection, it is possible to increase the tensile strength in the direction perpendicular to bonding surfaces 11, 21. In particular, by having a pair of bridge parts at all intersections in a uniform lattice arrangement, it is possible to maintain a uniform bonding strength [Invention 15].

[0080] As described above, the composite 1 and the manufacturing method thereof according to this embodiment employ a process in which a laser is irradiated onto the joining surface 11 to carve a plurality of grooves 30, 40, (35) in the form of filaments and these filaments are overlapped. By devising a method for overlapping the filaments, a bridged structure is formed on the joining surface 11 of the metal part 10 with bridge parts arranged in a desired manner. As a result, in a joining structure in which the grooves 30, 40, (35) formed on the joining surface 11 of the metal part 10 are filled with resin, when a vertical tensile stress is applied, the resin is less likely to come out of the grooves 30, 40, (35), improving the joining strength. Note that the composite and its manufacturing method according to the present invention are not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0081] For example, in the above embodiment, when the extension pattern (scanning pattern of the pulsed laser) of the first groove 30 or the second groove 40 is formed along one direction (Y direction) and another direction (X direction) intersecting therewith, it is not limited to a simple orthogonal pattern as described above, and it is possible to adopt intersecting patterns at various angles or patterns combining orthogonal patterns and intersecting patterns at various angles, including the third groove 35. In addition, the rows of linear patterns are not limited to being parallel to each other, and may be patterns including oblique ones.

[0082] In particular, in the case of a configuration having multiple intersecting grooves 30, 40, (35) in both directions as in the above embodiment, the intersection angle φ of the grooves between one direction (Y) and another direction (X) that intersects with the one direction (Y) is not limited to a right angle, and can be set to various angles, for example, within a range of approximately 45° to 90°.

[0083] Various modifications are also possible regarding the inclination angle, groove depth, spacing pitch between adjacent inclined grooves, groove width, etc. of each of the grooves 30, 40, (35). For example, in the composite 1 of the above embodiment, as an aspect of each groove formed on the joining surface 11 of the metal part 10, the groove width (W) of each groove can be appropriately set to about 250 μm or less.

[0084] Furthermore, by setting the inclination angle θ of each groove 30, 40, (35) to be between 5° and 60°, the volume of the undercut shape formed by the hook portion 60 can be increased according to the groove angle of the inclined groove, which is preferable for setting a high vertical tensile strength. Furthermore, by shortening the spacing pitch P, the volume of the undercut shape per unit area can be increased. [Explanation of symbols]

[0085] 1···· bumper reinforcement (composite), 10··· bumper beam (metal part), 11··· joint surface, 12··· back surface, 16, 17··· bending part, 18, 19··· mounting part, 20··· reinforcement part (resin part), 21··· joint surface, 22··· filled resin, 23··· metal bridge part and resin impregnated therein, 30··· vertical groove (first groove), 3 0a...first longitudinal groove, 30b...second longitudinal groove, 30c...third longitudinal groove, 40...lateral groove (second groove), 40a...first lateral groove, 40b...second lateral groove, 50A...first bridging portion, 50B...second bridging portion, 50C...third bridging portion, 60...hook portion (anchor), 70...mold set, 71, 72...mold, C...bridging structure

Claims

1. A composite body in which a metal part and a resin part are joined at opposing joining surfaces, The metal part is A first groove is formed in one direction on the joining surface of the metal portion; a second groove formed along another direction intersecting the first groove; a first bridge portion formed along the second groove at at least a portion of an intersection between the first groove and the second groove by a metal base material of the metal portion so as to connect both edges of the first groove; a second bridge portion formed along the first groove at at least a portion of an intersection between the first groove and the second groove so as to connect both edges of the second groove; having A composite body, characterized in that the joining surfaces of the resin parts are joined in a state in which the insides of the first groove and the second groove are filled with a resin base material.

2. The composite according to claim 1 , wherein the first crosslinked portion and the second crosslinked portion are continuously connected to each other to form an L-shaped crosslinked structure.

3. The first groove is formed in a plurality of stripes along the one direction, The second groove is formed in a plurality of stripes along the other direction, The pitch p and the groove width w of the first grooves and the second grooves are the same length, The composite according to claim 2, wherein the distance between the crosslinked portions including the bend of the L-shaped crosslinked structure (the distance between a first crosslinked portion and another adjacent second crosslinked portion) is 2p-w.

4. The first bridge portions are formed in pairs along both sides of the second groove, The composite according to claim 1 , wherein the second bridge portions are formed in pairs along both sides of the first groove.

5. The first groove is formed in a plurality of stripes along the one direction, The second groove is formed in a plurality of stripes along the other direction, The first bridge portion is provided in all the first grooves on the joining surface, The pitch p and the groove width w of the first grooves and the second grooves are the same length, 5. The composite according to claim 4, wherein the distance between the first crosslinked portion and another adjacent first crosslinked portion is 2pw or less.

6. The first groove is formed in a plurality of stripes along the one direction, The second groove is formed in a plurality of stripes along the other direction, The composite according to claim 4 , wherein at the other intersection adjacent to the intersection, the pair of first crosslinking portions and the pair of second crosslinking portions are alternately formed.

7. The first groove is formed in a plurality of stripes along the one direction, The second groove is formed in a plurality of stripes along the other direction, Further, a third groove is formed in a plurality of stripes along a direction different from the first groove and the second groove, the first bridge portion and a pair of third bridge portions formed at an intersection of the first groove and the second groove along the third groove, The pitch p and the groove width w of the first grooves and the second grooves are the same length, 5. The composite according to claim 4, wherein the distance between the first crosslinked portion or the third crosslinked portion and another adjacent crosslinked portion is 2p-w or less.

8. The composite body according to claim 1 , wherein the first groove and / or the second groove is formed obliquely in a depth direction of the joining surface of the metal portion.

9. The composite body according to claim 7 , wherein the third groove is formed obliquely in a depth direction of the joining surface of the metal portion.

10. 2. The composite according to claim 1, wherein in the first or second groove, the groove depth in a portion where the crosslinked portion is not present is greater than the groove depth in a portion where the crosslinked portion is present.

11. The composite body is a bumper reinforcement that is attached to a front or rear bumper of a vehicle body along a vehicle width direction, The metal part is a bumper beam made of metal and having two mounting parts for mounting to a vehicle body at both ends of its rear surface, The composite body according to any one of claims 1 to 10, wherein the resin portion is a resin reinforcing portion joined along a rear surface of the bumper beam.

12. A method for producing a composite in which a metal part and a resin part are joined at opposing joining surfaces, comprising the steps of: an L-shaped groove forming process for forming an L-shaped groove in the extending direction of the joining surface, the L-shaped groove being a first groove extending in one direction and a second groove extending in another direction intersecting the first groove and being continuous with each other, the L-shaped groove being formed in the extending direction of the joining surface; a joining process in which a molten resin is injected into the L-shaped groove formed in the metal part in the L-shaped groove forming process to fill the inside of the L-shaped groove, and a joining surface of the resin part is joined integrally to a joining surface of the metal part in a mold, A method for manufacturing a composite, characterized in that in the L-shaped groove forming process, a further continuous L-shaped groove is formed by shifting it in the extension direction of the joining surface so as to overlap at least a portion of the rectangular end of the corner of the L-shaped groove already formed, thereby forming an L-shaped bridge structure that connects both edges of the first and second grooves to each other at the overlapping rectangular end of the corner by the metal base material of the metal part.

13. A method for producing a composite in which a metal part and a resin part are joined at opposing joining surfaces, comprising the steps of: a groove forming step of forming a plurality of grooves opening on the joining surface of the metal portion; a joining process in which a molten resin is injected into the groove formed in the metal part in the groove forming process to fill the groove while integrally joining a joining surface of the resin part to a joining surface of the metal part in a mold; Including, The groove forming step includes: a first groove forming step of forming a first groove along one direction on the joining surface; a second groove forming step of forming a second groove along another direction intersecting the one direction; further repeating In the first groove forming step, the first groove is formed so as to intersect with the already formed second groove, thereby forming a pair of first bridge portions on both sides of the first groove at the intersection between the first groove and the second groove by the metal base material of the metal portion, the pair of first bridge portions respectively connecting both edges of the second groove; A method for producing a composite, characterized in that in the second groove forming step, the second groove is formed so as to intersect with the first groove that has already been formed, thereby forming a pair of second bridging portions on both sides of the second groove at the intersection between the second groove and the first groove by the metal base material of the metal part, respectively connecting both edges of the first groove.

14. The method for producing a composite according to claim 13, further comprising a replacement step of forming an additional groove along a groove in a direction intersecting the crosslinking direction of an already formed crosslinking portion, thereby replacing the crosslinking portion and forming a pair of crosslinking portions on both sides of the groove in the direction intersecting the crosslinking direction of the crosslinking portion.

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