JP2017039274A - Joining structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining structure having a stable and good joining strength.SOLUTION: A metal member (1) has a recessed portion (1b) formed on a joined surface (1a) which is joined with a resin member (2), and the recessed portion (1b) has an opening (1c) opened on the joined surface (1a), and an inner wall surface (1d) which is recessed toward inside of the metal member (1). The opening (1c) has a return portion (1c) extending in a direction narrowing the opening (1c) than an inner wall surface (1d). A hole depth H of the recessed portion (1d) is 60 μm or more and 120 μm or less. A surface area increase ratio Rs of the joined surface (1a) after the recessed portion (1b) has been formed to the joined surface (1a) before the recessed portion (1b) is formed is 3 times or more. An undercut length A from a middle point (1e) of a bottom (1g) of the recessed portions (1b) which are adjacent to each other to the opening (1c) is 10 μm or more and 20 μm or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a joining structure.

  There is a joint structure in which a metal member and a resin member are joined. For example, in patent document 1, after forming a hollow part in the metal member surface, the resin member is formed on the surface by insert-molding with a resin material. This hollow part has a return part extending in the direction of narrowing the opening from the bottom toward the opening. Therefore, the anchor effect is realized and the bonding strength between the metal member and the resin member is improved.

Japanese Patent Laying-Open No. 2015-094375

  Further, there is a demand for a joint structure that ensures stable and good joint strength. The joint structure disclosed in Patent Document 1 sometimes fails to ensure a stable and good joint strength.

  The present invention provides a joint structure having stable and good joint strength.

  The inventors of the present application have noticed that several factors such as the hole depth of the joint surface between the metal member and the resin member greatly affect the joint strength. Therefore, various investigations were conducted for each factor, and intensive research was performed to arrive at the invention of the present application.

The joint structure according to the present invention is:
A joining structure for joining a metal member and a resin member,
The metal member has a recess formed on a bonding surface to be bonded to the resin member,
The hollow portion has an opening that opens on the joint surface, and a hollow inner wall surface having a shape that is recessed toward the inside of the metal member,
The opening has a return portion extending in a direction of narrowing the opening than the inner wall surface,
The hole depth H of the recess is 60 μm or more and 120 μm or less,
The surface area increase rate Rs of the joint surface after forming the recess is 3 times or more with respect to the joint surface before forming the recess,
The undercut length A from the middle point between the bottoms of the adjacent recesses to the opening is 10 μm or more and 20 μm or less.

  The joint structure according to the present invention has a stable and good joint strength.

1 is a schematic cross-sectional view showing a joint structure according to Embodiment 1. FIG. 3 is a schematic cross-sectional view showing a main part of the joint structure according to Embodiment 1. FIG. 6 is a diagram illustrating a step of the method for manufacturing the joint structure according to Embodiment 1. FIG. 6 is a diagram illustrating a step of the method for manufacturing the joint structure according to Embodiment 1. FIG. 6 is a diagram illustrating a step of the method for manufacturing the joint structure according to Embodiment 1. FIG. 6 is a diagram illustrating a step of the method for manufacturing the joint structure according to Embodiment 1. FIG. 6 is a diagram illustrating a step of the method for manufacturing the joint structure according to Embodiment 1. FIG. It is a graph which shows the joint strength with respect to the hole depth H of an Example. It is a graph which shows the joining strength with respect to the surface area increase rate Rs of an Example. It is a graph which shows the joining strength with respect to the undercut length A of an Example.

Embodiment 1
With reference to FIG.1 and FIG.2, the junction structure which concerns on Embodiment 1 is demonstrated. FIG. 1 is a schematic cross-sectional view showing a joint structure according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing a main part of the joint structure according to the first embodiment. In FIG. 2, hatching is omitted for easy viewing.

  As shown in FIG. 1, the joining structure 100 has a structure in which a metal member 1 and a resin member 2 are joined. Specifically, the metal member 1 and the resin member 2 are bonded in a state where the bonding surface 1a of the metal member 1 and the bonding surface 2a of the resin member 2 are abutted.

  The metal member 1 is made of a metal material, for example, a steel material, aluminum, or an alloy thereof. Examples of the steel material include tool steel for molds. The joining surface 1a of the metal member 1 has a plurality of undercut portions 1b, and the plurality of undercut portions 1b are arranged on the joining surface 1a at a predetermined pitch.

  As shown in FIG. 2, the undercut part 1b is a hollow part, for example, a hole and a groove | channel. Moreover, the undercut part 1b is extended in the direction which narrows the said opening part rather than the inner wall surface 1d which has the opening part 1c opened in the joint surface 1a, the inner wall surface 1d dented toward the inner side of the metal member 1, and the said inner wall surface. And a return portion 1f. In other words, the return portion 1f is a portion extending from the inner wall surface 1d toward the center of the opening 1c when viewed from a position away from the opening 1c. Specifically, the undercut portion 1b is a hole having a space that extends larger than the opening portion 1c. More specifically, the undercut portion 1b is a hole in which at least a part of the inner wall surface 1d is located outside the opening 1c when viewed from a position away from the joint surface 1a of the metal member 1. The width of the opening 1c of the undercut portion 1b is preferably shorter than the width of at least a part of the space surrounded by the inner wall surface 1d of the undercut portion 1b.

  The undercut portion 1b has a predetermined hole depth H, and the adjacent undercut portions 1b are arranged at a hole pitch P. The hole depth H is preferably 60 μm or more and 120 μm or less, and the hole pitch P is preferably longer than 60 μm. The length from the middle point 1e of the bottom 1g between the undercut portions 1b adjacent to each other to the opening 1c is defined as an undercut length A. The bottom 1g may be near the center of the opening 1c. The undercut length A is preferably 10 μm or more and 20 μm or less.

  The resin member 2 is preferably made of a resin having a lower mechanical strength than the metal member 1, and is made of, for example, a thermosetting epoxy resin. The resin member 2 has a joint surface 2a that joins the joint surface 1a of the metal member 1, and a plurality of intrusion portions 2c that protrude from the joint surface 2a. The intrusion portion 2c enters the undercut portion 1b. It is preferable that the intrusion portion 2c and the joint surface 1a sandwich the return portion 1f. More preferably, the intrusion portion 2c has a shape that completely fills the inner space of the undercut portion 1b.

(Production method)
Next, with reference to FIGS. 3-7, the manufacturing method of the junction structure 100 concerning Embodiment 1 is demonstrated. 3-7 is a figure which shows 1 process of the manufacturing method of the junction structure which concerns on Embodiment 1. FIG.

  As shown in FIGS. 3 and 4, the metal base material 11 is compressed using the mold 8, and the mold 8 is ultrasonically vibrated in the direction along the molding surface 11 b of the metal base material 11, thereby The protrusion surface metal base material 12 having the portion 12a is formed (projection portion forming step S1). The mold 8 has a molding surface 8b and a projection 8a that projects from the molding surface 8b. The mold 8 is formed by using, for example, electric discharge machining or cutting of tool steel. The mold 8 preferably has higher mechanical strength than the metal base material 11. The metal base material 11 is made of the same type of material as the metal member 1 (see FIG. 1) and has a molding surface 11b. The protrusion surface metal base material 12 has a bottom 12b between adjacent protrusions 12a.

  Specifically, the molding surface 11b is compressed by causing the molding surface 8b and the molding surface 11b to face each other and the metal mold 8 abut against the metal base material 11. Then, at least a part of the molding surface 11b of the metal base material 11 flows between the molds 8, particularly between the adjacent protrusions 8a. Further, the metal base material 11 flows between the adjacent protrusions 8a by ultrasonically vibrating the mold 8 in the direction along the molding surface 11b while the metal mold 8 is abutted against the metal base material 11. Promote. The mold 8 may be ultrasonically vibrated in the direction along the molding surface 8b.

Here, as shown in FIG. 5, the distance between the tips 8c of the adjacent protrusions 8a is the uneven pitch p [mm], and the height from the molding surface 8b to the protrusion 8a is the protrusion height h [μm. ], And the angle of the tip 8c is the protrusion tip angle θ [°]. Further, the distance from the molding surface 11b of the metal base material 11 to the bottom 12b is defined as a processing amount d1 [mm] (see FIG. 4). It is preferable that the uneven pitch p, the protrusion height h, the protrusion tip angle θ, and the processing amount d1 satisfy the following expressions 2 to 5.
0.1 ≦ p ≦ 1.5 (Formula 2)
h ≧ 2p (Formula 3)
20 ≦ θ ≦ 45 (Formula 4)
0.1 ≦ d1 ≦ 1.5 (Formula 5)

  The vibration frequency f [kHz] of the ultrasonic wave added to the mold 8 is preferably 15 to 28, and the vibration amplitude A [μm] is preferably 10 to 150. In other words, the vibration amplitude A is preferably 10% of the uneven pitch p. The compression speed Vp [mm / sec] of the mold 8 can be set so as to be within the range of 0.1 to 10. Further, the molding surface 11b may be a three-dimensional shape, for example, an end face of a rectangular plate, instead of the plane shown in FIGS.

Subsequently, as shown in FIGS. 6 and 7, the metal surface 9 is compressed using the metal plate 9 to form the metal member 1 having the undercut portion 1b (undercut portion forming step S2). . The metal plate 9 has a smooth surface 9a. The number of compressions may be multiple. For example, by the first compression, the tip of the projection 12a is deformed so that the tip of the projection 12a has an angle, specifically, more than 0 (zero) ° and less than 180 °. Furthermore, the tip of the protrusion 12a is deformed by the second compression. The return portion 1f can be formed by these two compressions.
In addition, the wall surface and bottom part 12b of the projection part 12a respond | correspond to the undercut part 1b. The distance from the protrusion 12a of the protrusion surface metal base material 12 to the joint surface 1a of the metal member 1 is defined as a compression amount d2 [mm]. When the compression amount d2 is increased, the overlap amount x is increased and the undercut portion 1b is narrowed. Here, the overlap amount x is the length of the return portion 1f. It is preferable that the compression amount d2 satisfy Expression 6 below because the opening 1c of the undercut portion 1b is less likely to be blocked due to excessive deformation of the return portion 1f.
d2 ≦ 1 / 2h (Formula 6)

  Subsequently, after the resin material constituting the resin member 2 is filled in the undercut portion 1b of the metal member 1, the resin member 2 and the metal member 1 are joined by solidifying (joining step S3). Here, a part of the joint surface 2a of the resin member 2 formed by filling the inside of the undercut portion 1b and solidifying is referred to as an intrusion portion 2c.

  As described above, through the steps, the joint structure 100 in which the resin member 2 and the metal member 1 are joined is formed.

  By the way, in the joining structure 100, the metal member 1 has the undercut part 1b which has a predetermined size, and the penetration | invasion part 2c of the resin member 2 has penetrate | invaded the undercut part 1b. Therefore, the joining surface 1a of the metal member 1 and the joining surface 2a of the resin member 2 are joined with a large surface area, and the intrusion portion 2c is larger than the opening portion 1c. Further, the intrusion portion 2c and the joint surface 2a sandwich the return portion 1f. Here, when the resin member 2 and the metal member 1 are pulled apart from each other, the intrusion portion 2c and the return portion 1f are engaged with each other, thereby providing an anchor effect. Further, since the hole depth H, the hole pitch P, and the undercut length A are within the predetermined ranges, the joint structure 100 has a stable and good joint strength.

  As described above, according to the joint structure according to the first embodiment, the joint structure has a stable and good joint strength.

  By the way, the joining structure 100 can be applied as long as it is a resin-sealed part, and is preferably used for a cooler of an inverter, for example. Since the joint structure 100 has a good joint strength, the joint structure 100 can satisfy the water pressure resistance and the mechanical strength necessary as components of the inverter cooler.

  Next, examples of the joint structure according to the first embodiment will be described. Each condition was set and the relationship with the bonding strength was investigated. As the metal member 1 of the example, a block body made of an aluminum alloy was used. Moreover, as the resin member 2 of an Example, the block body which consists of a thermosetting epoxy resin was used.

Specifically, the implementation condition for the hole depth H was selected from a plurality of levels within the range of 30 to 100 μm. As the execution condition of the hole pitch P, a plurality of levels were selected from the range of 30 to 80 μm. The hole pitch P of about 30 to 80 μm corresponds to a surface area increase rate Rs of about 1 to 4 times. The surface area increase rate Rs is an increase in the area of the joint surface 1a after forming the undercut portion 1b with respect to the area of the joint surface 1a (see FIG. 2) before forming the undercut portion 1b (see FIG. 2). Rate. The area of the joint surface 1a can be calculated by image measurement, for example. Further, the surface area increase rate Rs can be estimated using, for example, the following relational expression 1.
Rs = 5 × H / P ² (Relational formula 1)
When the hole pitch P decreases, the surface area increase rate Rs tends to increase. The implementation conditions for the undercut length A were selected from a plurality of levels within the range of about 5 to 30 μm.

  The tensile strength when the joining structure according to the example was pulled in a direction substantially perpendicular to the joining surface was measured, and the measured tensile strength was defined as the joining strength. The bonding strength with respect to the hole depth H, the surface area increase rate Rs, or the undercut length A under predetermined conditions is shown in FIGS.

  As shown in FIG. 8, with a hole pitch P of 60 μm and an undercut length A of 10 μm, the bonding strength tends to increase as the hole depth H increases. When the hole depth H was about 30 μm, the bonding strength was about 25 MPa, and when the hole depth H was about 90 μm, the bonding strength was about 32 MPa. If the hole depth H is about 60 μm or more, the bonding strength is estimated to be 30 MPa or more. The bonding strength of 30 MPa corresponds to the tensile strength of a block body made of a thermosetting epoxy resin. For this reason, since the joining structure having a joining strength of 30 MPa is not easily broken at the joining surface even if it is pulled or broken, the joining strength of 30 MPa is set to a good value.

  As shown in FIG. 9, when the hole depth H is 100 μm and the undercut length A is 10 μm, the bonding strength tends to increase as the surface area increase rate Rs increases. When the surface area increase rate Rs is about 1.5 times, the bonding strength is about 23 MPa, and when the surface area increase rate Rs is about 3.5 times, the bonding strength is about 32 MPa. If the surface area increase rate Rs is about 3 times or more, it is estimated that the bonding strength is 30 MPa or more. Here, the surface area increase rate Rs3 times corresponds to the hole pitch P60 μm.

  As shown in FIG. 10, when the hole depth is H100 μm, the hole pitch P is 60 μm, and the undercut length A is in the range of about 5 to 18 μm, the joint strength increases as the undercut length A increases. There is a tendency. On the other hand, when the hole depth was H100 μm, the hole pitch P was 60 μm, and the undercut length A was about 22 μm or more, the bonding strength was substantially 0 (zero) regardless of the value of the undercut length A. One possible reason is that the penetration of the resin material into the undercut portion is suppressed. When the undercut length A was about 10 μm, the joint strength was about 32 MPa, and when the undercut length A was about 18 μm, the joint strength was about 40 MPa. If the undercut length A is in the range of about 10 to about 20 μm, the bonding strength is estimated to be 30 MPa or more.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Joining structure 1 Metal member 1a Joining surface 1b Undercut part 1c Opening part 1d Inner wall surface 1e Middle point 1f Return part 1g Bottom 2 Resin member P Hole pitch Rs Surface area increase rate H Hole depth

Claims (1)

A joining structure for joining a metal member and a resin member,
The metal member has a recess formed on a bonding surface to be bonded to the resin member,
The hollow portion has an opening that opens on the joint surface, and a hollow inner wall surface having a shape that is recessed toward the inside of the metal member,
The opening has a return portion extending in a direction of narrowing the opening than the inner wall surface,
The hole depth H of the recess is 60 μm or more and 120 μm or less,
The surface area increase rate Rs of the joint surface after forming the recess is 3 times or more with respect to the joint surface before forming the recess,
A junction structure in which an undercut length A from the middle point of the bottom of adjacent recesses to the opening is 10 μm or more and 20 μm or less.

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