Joined structure and method for manufacturing the joined structure

Abstract

A bonded structure according to one aspect of the present disclosure includes an aluminum member, one or more metal members, and an adhesive for bonding the aluminum member and the metal member, wherein the aluminum member has one or more protrusions, the metal member has one or more through holes, and the protrusions are inserted into the through holes and crimped.A method for manufacturing a bonded structure according to another aspect of the present disclosure includes the steps of applying adhesive to one or both of the aluminum member having one or more protrusions and the metal member having one or more through holes, bonding the aluminum member and the metal member using the adhesive while inserting the protrusions into the through holes, deforming the tips of the protrusions to crimp the protrusions into the through holes, and curing the adhesive.

Description

[Technical Field]

[0001] The present disclosure relates to a bonded structure and a method for manufacturing the bonded structure. This application claims priority based on Japanese Patent Application No. 2024-177841, filed on October 10, 2024, the contents of which are incorporated herein by reference. [Background technology]

[0002] In recent years, aluminum die casting has been increasingly applied to various mechanical structural parts. Aluminum die casting refers to an aluminum alloy casting or a casting method that is obtained by filling a molten aluminum alloy into a mold under high pressure and then rapidly cooling the aluminum alloy. Aluminum die casting is used, for example, as a material for automobile front shock towers, rear shock towers, and subframes.

[0003] In recent years, a manufacturing technology known as Gigacast has also been developed. Gigacast is a technology that uses large casting equipment to mold multiple aluminum parts into a single part, producing huge components. By casting the components that make up an automobile body into large parts, it is possible to reduce the weight of the automobile, manufacturing costs, and manufacturing processes. For this reason, the application of Gigacast is expected to expand in the future. Furthermore, with the advancement of automobile electrification, aluminum die casting is beginning to be used in inverter cases, battery modules, and battery packs.

[0004] The aluminum die-cast member exemplified above needs to be joined to another member. The other member may be, for example, a press-formed steel plate, an aluminum wrought material, etc. For example, Patent Documents 1 to 5 disclose various methods for joining an aluminum die-cast member to another member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 3-86381 [Patent Document 2] Japanese Patent Application Publication No. 11-77192 [Patent Document 3] Japanese Patent Application Publication No. 59-166330 [Patent Document 4] Japanese Patent Application Publication No. 56-111529 [Patent Document 5] Japanese Patent Application Laid-Open No. 2006-21249 Summary of the Invention [Problem to be solved by the invention]

[0006] Welding is difficult to use as a means of joining aluminum die-cast and non-aluminum materials. For example, when welding an aluminum die-cast member to a steel member, brittle intermetallic compounds form in the weld metal. These brittle intermetallic compounds significantly reduce the joint strength of the weld.

[0007] Another method of joining aluminum die castings to non-aluminum materials is mechanical joining using fasteners, etc. However, aluminum die castings have the problem that the joints formed by mechanical joining are prone to cracking. The joints are prone to deformation due to stress concentration. Because aluminum die castings have low ductility, deformation at the joints can easily cause cracks in the aluminum die castings.

[0008] The inventors attempted to use adhesives as a means of joining aluminum components to other components. Adhesives can easily join dissimilar metals. Furthermore, because adhesives join components by surface bonding, deformation due to stress concentration is unlikely to occur.

[0009] However, when joining aluminum components to other components, a process is required for the adhesive to harden. The joined components must be held in a temporary state until the adhesive hardens. Therefore, auxiliary materials such as self-piercing rivets, bolts, and FDS are required to bond aluminum components.

[0010] The use of secondary materials increases the manufacturing cost and weight of mechanical structural parts. Furthermore, the use of secondary materials may require specialized joining equipment. Therefore, there is a need for technology that can join aluminum components to other components without using secondary materials.

[0011] In view of the above circumstances, the present disclosure provides a joined structure including aluminum members that can be manufactured inexpensively, in a short time, and without cracks, using general-purpose equipment without using auxiliary materials, and a method for manufacturing the same. [Means for solving the problem]

[0012] The gist of the present disclosure is as follows.

[0013] (1) A bonded structure according to one embodiment of the present disclosure is a bonded structure comprising an aluminum member, one or more metal members, and an adhesive for bonding the aluminum member and the metal members, wherein the aluminum member has one or more protrusions, the metal member has one or more through holes, and the protrusions are inserted into the through holes and crimped. (2) Preferably, in the joined structure described in (1) above, the aluminum member is an aluminum die-cast member. (3) Preferably, in the joined structure described in (2) above, the protrusions of the aluminum members are formed during die casting. (4) Preferably, in the joined structure according to any one of (1) to (3) above, the metal member is a plated steel material. (5) In the joined structure described in (4) above, the plated steel material is preferably an aluminum-based plated steel material or a zinc-based plated steel material. (6) Preferably, in the joined structure according to any one of (1) to (5) above, the metal member is a painted steel material or a chromate-free treated steel material. (7) Preferably, in the joined structure according to any one of (1) to (5) above, the material of the metal member is an aluminum alloy. (8) Preferably, in the joint structure according to any one of (1) to (7) above, the adhesive is disposed between the protrusion and the inner wall of the through hole. (9) Preferably, in the joint structure described in (8) above, one or both of the through hole and the protrusion inserted into the through hole have a tapered shape that narrows from the base end of the protrusion toward the tip. (10) Preferably, in the joined structure according to any one of (1) to (9) above, the cross-sectional area of ​​the base end of the protrusion is larger than the area of ​​the through hole on the side facing the aluminum member. (11) Preferably, in the joined structure described in any one of (1) to (10) above, the hardness H1 of the tip of the protrusion and the hardness H2 of the aluminum member at a location 10 mm or more away from the protrusion satisfy H1≦1.1×H2.

[0014] (12) Another aspect of the present disclosure provides a method for manufacturing a joined structure having an aluminum member, one or more metal members, and an adhesive for joining the aluminum member and the metal member, the method comprising the steps of: applying the adhesive to one or both of the aluminum member having one or more protrusions and the metal member having one or more through holes; bonding the aluminum member and the metal member together using the adhesive while inserting the protrusions into the through holes; deforming the tips of the protrusions to crimp the protrusions into the through holes; and hardening the adhesive. (13) Preferably, in the method for manufacturing a joint structure according to (12) above, the protrusion is heated when the protrusion is caulked into the through hole. (14) Preferably, in the method for manufacturing a joint structure described in (13) above, the protrusion is heated and the tip of the protrusion is deformed using a spot welding electrode. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to provide a joined structure including aluminum members that can be manufactured inexpensively, in a short time, and without cracks, using general-purpose equipment without using auxiliary materials, and a method for manufacturing the same. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. [Figure 2] 10 is a cross-sectional photograph of an example of a bonded structure in which an adhesive is disposed between a protrusion and an inner wall of a through hole. [Figure 3] FIG. 10 is a cross-sectional view of a joint structure in which both the through hole and the protrusion have a tapered shape. [Figure 4] 10 is a cross-sectional view of a joined structure in which the cross-sectional area of ​​the base end of the protrusion is larger than the area of ​​the side of the through hole facing the aluminum member. FIG. [Figure 5] FIG. 10 is a schematic diagram illustrating a step of applying an adhesive. [Figure 6] 1A and 1B are schematic diagrams illustrating a process for joining an aluminum member and a metal member. [Figure 7] 10A and 10B are schematic diagrams illustrating a process of deforming the tip of a protrusion using a direct spot welding machine. [Figure 8] FIG. 10 is a schematic diagram illustrating a process of deforming the tip of a protrusion using an indirect spot welding machine. [Figure 9] FIG. 10 is a schematic diagram illustrating a step of curing an adhesive. [Figure 10] This is a reference to Figure 2.9 "Typical macroscopic solidification structures" in "Mechanical Engineering Handbook β. Design Edition: Processing Science and Processing Equipment." DETAILED DESCRIPTION OF THE INVENTION

[0017] (1.Joint structure 1) 1, a joined structure 1 according to one embodiment of the present disclosure includes an aluminum member 11, one or more metal members 12, and an adhesive 13 that joins the aluminum member 11 and the metal members 12, wherein the aluminum member 11 has one or more protrusions 111, the metal members 12 have one or more through holes 121, and the protrusions 111 are inserted into the through holes 121 and crimped. Details of the joined structure 1 according to this embodiment will be described below.

[0018] (Aluminum component 11) The joined structure 1 has an aluminum member 11. The aluminum member 11 is a mechanical structural member made of an aluminum alloy. Specific examples of aluminum alloys will be described later.

[0019] The aluminum member 11 can be applied in various shapes depending on its application. Suitable examples of applications of the aluminum member 11 include front shock towers, rear shock towers, and subframes of automobiles. The aluminum member 11 can also be used as a component that constitutes the electrical system of an electric vehicle, such as an inverter case, a battery module, and a battery pack. Note that one joined structure 1 may include two or more aluminum members 11.

[0020] (Metal member 12 and adhesive 13) The joined structure 1 further includes a metal member 12 and an adhesive 13. The metal member 12 is joined to the aluminum member 11 by the adhesive 13. The metal member 12 is a mechanical structural member made of metal. The metal member 12 is joined to the aluminum member 11 by the adhesive 13. The metal member 12 can also be applied to various shapes depending on its application. A suitable example of a material for the metal member 12 is a plated steel sheet. Specific examples of metals that make up the metal member 12 will be described later.

[0021] (Protrusion 111 and through hole 121) The aluminum member 11 has a protrusion 111. The metal member 12 has a through hole 121. The protrusion 111 of the aluminum member 11 is inserted into the through hole 121 of the metal member 12. The protrusion 111 is also crimped. Specifically, the protrusion 111 has a tip 1112 and a shaft 1111, and the tip 1112 is plastically deformed by crimping. The shaft 1111 is the portion of the protrusion 111 that is arranged inside the through hole 121. The tip 1112 is the portion of the protrusion 111 on the tip side that is arranged outside the through hole 121.

[0022] When the protrusion 111 and the through hole 121 are cut on a plane perpendicular to the axial direction of the through hole 121, the diameter of the shaft 1111 in the cross section is the same as or smaller than the diameter of the through hole 121. The diameter of the tip 1112 is enlarged by plastic deformation to be larger than the diameter of the outlet of the through hole 121. The outlet of the through hole 121 refers to the end of the through hole on the tip 1112 side. The tip 1112 prevents the protrusion 111 from coming off the through hole 121. The protrusion 111 functions to join the aluminum member 11 and the metal member 12, like a rivet. However, the protrusion 111 differs from a rivet in that it is integral with the aluminum member 11.

[0023] The aluminum member 11 may have two or more protrusions 111. The metal member 12 may have two or more through holes 121. In this case, it is preferable that the plurality of protrusions 111 are inserted into the plurality of through holes 121 and crimped.

[0024] When the protrusion 111 and the through hole 121 are cut along a plane perpendicular to the axial direction of the through hole 121, the cross-sectional shape of the protrusion 111 and the through hole 121 can be, for example, a circle, an ellipse, or a polygon. The positions of the protrusion 111 and the through hole 121 are not particularly limited, but are preferably within the region where the adhesive 13 is applied. In other words, it is preferable that the peripheral portions of the protrusion 111 and the through hole 121 are adhered.

[0025] (Action and effect) The adhesive 13 can easily join the metal member 12 and the aluminum member 11. Furthermore, because the adhesive 13 joins the members by surface bonding, deformation due to stress concentration is unlikely to occur in the aluminum member 11 or the metal member 12. Therefore, at the joint formed by the adhesive 13, the metal member 12 and the aluminum member 11 are unlikely to break.

[0026] However, when joining the aluminum member 11 and the metal member 12, a process of curing the adhesive 13 is required. The metal member 12 and the aluminum member 11 need to be held in a temporarily joined state until the adhesive 13 hardens. Therefore, when joining the aluminum member 11, secondary materials are required for the temporary joining. Examples of secondary materials include self-piercing rivets, bolts, and FDS. The use of secondary materials increases the manufacturing cost and weight of mechanical structural parts. Furthermore, the use of secondary materials may require dedicated joining equipment.

[0027] On the other hand, the joined structure 1 according to the present disclosure has protrusions 111 and through holes 121 that mechanically join the metal member 12 to the aluminum member 11. The protrusions 111 and through holes 121 can hold the metal member 12 and the aluminum member 11 in a temporarily joined state until the adhesive 13 hardens in the step of hardening the adhesive 13. Therefore, in manufacturing the joined structure 1 according to the present disclosure, no secondary materials for temporary joining are required.

[0028] 6 and 7, which will be described later, the tip of the protrusion 111A provided on the aluminum member 11 before it is joined to the metal member 12 can be crimped using a spot welding machine, which is a general-purpose piece of equipment. The spot welding machine has a spot welding electrode 2, a pressure device that moves the spot welding electrode 2, and a transformer that applies current to the spot welding electrode 2. The spot welding electrode 2 applies pressure while locally heating the material to be welded by passing current through it.

[0029] The spot welding machine can be easily adapted for use in the crimping operation of the protrusion 111A of the aluminum member 11. The spot welding machine can apply electrical heat to the protrusion 111A of the aluminum member 11 inserted into the through hole 121 of the metal member 12. This heats the tip of the protrusion 111A and thermally softens the protrusion 111A. The spot welding machine can also apply pressure to the protrusion 111A of the aluminum member 11. By applying pressure to the tip 1112 of the thermally softened protrusion 111A, the tip 1112 can be easily plastically deformed. Therefore, when manufacturing the joined structure 1 according to the present disclosure, dedicated equipment for temporary fastening is not required. Temporary fastening can be performed using a spot welding machine, which is a general-purpose welding equipment.

[0030] Furthermore, the crimping operation using a spot welder can be performed inexpensively and in a short time, and does not cause cracks in the protrusions 111. Resistive heating using an electrode can thermally soften the tip 1112 of the protrusions 111 of the aluminum member 11 within a few seconds. Therefore, the crimping operation can be completed in an extremely short time and at low cost. Furthermore, although the aluminum alloy that constitutes the aluminum member 11 is prone to cracking during plastic deformation, the thermally softened aluminum alloy does not crack due to plastic deformation.

[0031] For the above reasons, the joined structure 1 of this embodiment can be manufactured inexpensively, in a short time, and without causing cracks in the aluminum member 11, using a spot welding machine, which is a general-purpose welding equipment, without using any auxiliary materials.

[0032] Note that if a strong stress is applied to the protrusion 111 of the aluminum member 11, the protrusion 111 may be damaged. However, in the joined structure 1 according to this embodiment, high bonding strength is not required of the protrusion 111. The bonding strength is ensured by the adhesive 13. Therefore, even if the protrusion 111 is damaged, the bonding strength of the joined structure 1 is not impaired. The bonding strength of the protrusion 111 need only be strong enough to temporarily fasten the aluminum member 11 and the metal member 12 together when the adhesive 13 is hardened. Furthermore, in the joined structure 1 according to this embodiment, the adhesive 13 bonds the aluminum member 11 and the metal member 12 together by surface bonding. Even if a strong external force is applied to the joined structure 1, the amount of movement of the metal member 12 relative to the aluminum member 11 is extremely small. Therefore, the possibility of strong stress being applied to the protrusion 111 is negligibly low.

[0033] The most basic aspect of the joined structure 1 according to this embodiment has been described above. A more preferred aspect will now be described.

[0034] (aluminum die-cast parts) A suitable example of the aluminum member 11 is an aluminum die-cast member. An aluminum die-cast member is a mechanical structural member made of aluminum die-cast. Aluminum die-casting is an aluminum alloy casting obtained by filling a molten aluminum alloy into a mold under high pressure and then rapidly cooling the aluminum alloy. Aluminum die-cast members have excellent strength and can be manufactured in a short time.

[0035] When observing the cross section of an aluminum die-cast member, a fibrous metal structure called metal flow can be observed. Metal flow is a trace of the flow of molten aluminum during casting. An aluminum member 11 having metal flow is considered to be an aluminum die-cast member. It is desirable to form a cross section for observing the metal flow parallel to the surface of the aluminum member 11.

[0036] Specific examples of aluminum alloys that may be used to form the aluminum member 11 include Al-Si-Cu alloys such as ADC10 and ADC12, Al-Si-Mg alloys such as AC4CH and AC4C, Al-Mg-Si-Mn alloys, and Al-Si-Cu-Mg-Ni alloys.

[0037] (Metal flow of protrusion 111) There is no limitation on the method for manufacturing the protrusions 111. For example, the protrusions 111 can be formed by cutting the aluminum member 11 or by welding a protrusion part that is manufactured separately from the aluminum member 11 to the aluminum member 11.

[0038] When the aluminum member 11 is a die-cast member, it is preferable that the protrusions 111 of the aluminum member 11 are formed during die-casting. This reduces the number of steps required to form the protrusions 111 and suppresses cracks in the protrusions 111 and their surroundings.

[0039] When a cross section of a protrusion 111 of an aluminum member 11 formed during die casting is corroded and observed, metal flow patterns can be visually observed inside the protrusion 111. The cross section is corroded using a mixture of 10% by volume of ammonia and water, or Keller's solution. The protrusion 111 with metal flow patterns has chill crystals on its surface and columnar crystals inside. Furthermore, equiaxed crystals may also be present inside the metal flow patterns. The columnar crystals exist radially from the inside to the outside of the protrusion 111. Note that the cross section for observing the metal flow patterns of the protrusion is preferably taken along the thickness direction of the plated steel member, passing through the central axis of the protrusion. The cross section is preferably observed using an optical microscope at a magnification of 50x, for example.

[0040] The shapes of chill crystals, columnar crystals, and equiaxed crystals are shown, for example, in Figure 2.9, "Typical Macroscopic Solidification Structure," on page β-3 of Volume β3, "Processing Science and Processing Equipment," of the "Mechanical Engineering Handbook, β. Design Edition" (edited by the Japan Society of Mechanical Engineers, Maruzen Co., Ltd., published April 30, 2008). For reference, this figure is cited as Figure 10 in this disclosure. Chill crystals, columnar crystals, and equiaxed crystals can be identified by observing the etched cross section. Furthermore, protrusions where crystals are arranged, such as those shown in (a) and (b) in this figure, are considered to be protrusions formed during die casting.

[0041] Furthermore, the protrusions 111 formed during die casting are integrally formed with the aluminum member 11. Therefore, the protrusions 111 that have metal flow lines extending along the surface of the protrusions 111 and are integrally formed with the aluminum member 11 are considered to be protrusions 111 formed during die casting.

[0042] Metal flow may also be observed in the cross section of the protrusion 111 formed by cutting. However, if the protrusion is formed by casting and then machined, such as by cutting, the chill crystals may disappear by cutting. In that case, the protrusion 111 is composed of only columnar crystals, or of columnar crystals and equiaxed crystals. Furthermore, cutting marks may remain on the surface of the protrusion 111 formed by cutting. Therefore, the protrusion 111 formed by cutting and the protrusion 111 formed during die casting can be distinguished by observing the surface and cross section.

[0043] (Material of metal member 12) The material of the metal member 12 is not particularly limited. The material of the metal member 12 may be a metal different from that of the aluminum member 11. Because the adhesive 13 is present between the aluminum member 11 and the metal member 12, the area where the aluminum member 11 and the metal member 12 are in direct contact is small. Therefore, in the joined structure 1 according to this embodiment, galvanic corrosion is suppressed between the aluminum member 11 and the metal member 12.

[0044] A suitable example of the material for the metal member 12 is plated steel. Plated steel has a base steel material and a plating layer formed on the surface of the base steel material. The base steel material of plated steel has high strength. Therefore, plated steel contributes to increasing the strength and reducing the weight of the joined structure 1. Furthermore, the plating layer of plated steel suppresses corrosion of the base steel material. Therefore, plated steel contributes to ensuring the corrosion resistance of the joined structure 1.

[0045] Suitable examples of plated steel materials are aluminum-based plated steel materials and zinc-based plated steel materials. Aluminum-based plated steel materials are steel sheets having a base steel material and an aluminum-based plating layer formed on the surface of the base steel material, with the average aluminum concentration in the plating layer being 20 mass% or more. Zinc-based plated steel materials are steel sheets having a base steel material and a zinc-based plating layer formed on the surface of the base steel material, with the average zinc concentration in the plating layer being 30% or more. Both the aluminum-based plating layer and the zinc-based plating layer are effective in further suppressing galvanic corrosion between the base steel material and the aluminum member 11.

[0046] A specific example of an aluminum-plated steel material is an aluminum-plated hot-stamped steel sheet. Specific examples of a zinc-plated steel material are a zinc-plated hot-stamped steel sheet, a GA-plated (galvannealed) steel sheet, a GI-plated (hot-dip galvanized) steel sheet, an EG-plated (electrogalvanized) steel sheet, a Zn-Ni-plated steel sheet, a Zn-Al-Mg-plated steel sheet, and a Zn-Mg-plated steel sheet.

[0047] The metal member 12 may be a painted steel material or a chromate-free treated steel material. The painted steel material has a base steel material and a resin coating film provided on the surface of the base steel material. The chromate-free treated steel material has a base steel material and a chromate-free treated layer provided on the surface of the base steel material. Both the painted steel material and the chromate-free treated steel material contribute to ensuring the corrosion resistance of the joined structure 1 and further suppressing galvanic corrosion between the base steel material and the aluminum member 11. A plating may be provided between the base steel material and the coating film or chromate-free treated layer. Examples of the plating layer that the painted steel material or the chromate-free treated steel material has are as described above.

[0048] The material of the metal member 12 may be an aluminum alloy, similar to the aluminum member 11. A specific example of the material of the metal member 12 is a 5000 series, 6000 series, or 7000 series wrought aluminum material specified in JIS H 4000:2017 "Aluminum and aluminum alloy plate and strip." Alternatively, the metal member 12 may be an aluminum die-cast having through holes 121.

[0049] (Position of adhesive 13) When the metal member 12 is a plated steel material and the through hole 121 is formed after the formation of a plating layer, the plating layer is not present on the inner wall of the through hole 121 of the metal member 12, and the base steel material is exposed. In this case, the base steel material of the metal member 12 and the aluminum member 11 come into contact with each other on the inner wall of the through hole 121, which may cause galvanic corrosion.

[0050] Therefore, in the joined structure 1 according to this embodiment, an adhesive 13 is preferably disposed between the protrusion 111 and the inner wall of the through hole 121. The adhesive 13 prevents contact between the protrusion 111 and the inner wall of the through hole 121, thereby further improving the corrosion resistance of the joined structure 1. The adhesive 13 only needs to be disposed in at least a portion of the region between the protrusion 111 and the inner wall of the through hole 121. For example, in the joined structure 1 shown in FIG. 2, when the area between the protrusion 111 and the inner wall of the through hole 121 is magnified with a microscope, it can be seen that a layer of adhesive 13 several micrometers thick is intermittently present. In the present disclosure, the length of the adhesive 13 that has penetrated between the protrusion 111 and the inner wall of the through hole 121, as determined in the cross section of the joint, along the inner wall, is defined as the "penetration length of the adhesive 13." When the adhesive 13 is present intermittently between the protrusion 111 and the inner wall of the through hole 121, the total length of all adhesive 13 is considered to be the penetration length of the adhesive 13. Furthermore, in the present disclosure, the value obtained by dividing the penetration length of the adhesive 13 by the thickness of the metal member 12 is defined as the "penetration rate of the adhesive 13." The penetration rate of the adhesive 13 is preferably greater than 0%, 2% or more, 5% or more, 10% or more, 20% or more, or 30% or more. The penetration rate of the adhesive 13 is preferably 100% or less, 80% or less, 60% or less, or 50% or less.

[0051] Fig. 2 shows a cross-sectional photograph of an example of a joined structure 1 in which adhesive 13 is disposed between protrusion 111 and the inner wall of through hole 121. In the cross-sectional view of Fig. 2, adhesive 13, which is disposed between aluminum member 11 and metal member 12 to join them, leaks out onto the outer surface of metal member 12 through through hole 121. Therefore, although it cannot be seen in the photograph of Fig. 2, a thin layer of adhesive 13 is also present between protrusion 111 and the inner wall of through hole 121. In such a joined structure 1, galvanic corrosion is further suppressed.

[0052] (Tapered shape of through-hole 121 and / or protrusion 111) Preferably, one or both of the through hole 121 and the protrusion 111 inserted into the through hole 121 have a tapered shape that narrows from the base end 1113 of the protrusion 111 toward the tip end. Fig. 3 shows an example of a joined structure 1 in which both the through hole 121 and the protrusion 111 have a tapered shape.

[0053] By applying a tapered shape to the through hole 121 and / or the protrusion 111, the adhesive 13 can easily flow between the protrusion 111 and the inner wall of the through hole 121. This makes it even easier to distribute the adhesive 13 between the protrusion 111 and the inner wall of the through hole 121. Furthermore, by applying a tapered shape to the through hole 121 and / or the protrusion 111, the operation of inserting the protrusion 111 into the through hole 121 becomes easier. This improves the manufacturing efficiency of the joined structure 1.

[0054] (Relationship between the cross-sectional area of ​​the base end 1113 of the protrusion 111 and the area of ​​the through-hole 121) Preferably, as illustrated in FIG. 4 , the cross-sectional area of ​​the base end 1113 of the protrusion 111 is larger than the area of ​​the side of the through hole 121 facing the aluminum member 11. The cross-sectional area of ​​the base end 1113 of the protrusion 111 refers to the area of ​​a cross section obtained when the protrusion 111 is cut from the aluminum member 11 along the surface on which the protrusion 111 is provided. The cross-sectional area of ​​the base end 1113 of the protrusion 111 can be measured by cutting the protrusion 111 along the dashed line labeled A in FIG. 4 . The area of ​​the side of the through hole 121 facing the aluminum member 11 refers to the area of ​​the through hole 121 on the surface of the metal plate on which the through hole 121 is provided that is joined to the aluminum member 11. The area of ​​the through hole 121 measured along the dashed line labeled B in FIG. 4 refers to the area of ​​the side of the through hole 121 facing the aluminum member 11.

[0055] If the cross-sectional area of ​​the base end 1113 of the protrusion 111 is larger than the area of ​​the side of the through-hole 121 facing the aluminum member 11, the base end 1113 of the protrusion 111 cannot enter the inside of the through-hole 121. Similarly, the portion around the base end 1113 that has a larger cross-sectional area than the through-hole 121 cannot enter the inside of the through-hole 121 either. These portions create a gap between the surface of the metal member 12 and the aluminum member 11. In other words, by changing the shape of the base end 1113 of the protrusion 111 and its surrounding area, as well as the shape of the through-hole 121, the gap between the metal member 12 and the aluminum member 11 can be freely controlled.

[0056] The thickness of the adhesive 13 is preferably optimized depending on its properties and purpose. By matching the gap between the metal member 12 and the aluminum member 11 with the optimal thickness of the adhesive 13, the capabilities of the adhesive 13 can be maximized, further increasing the joining strength of the joined structure 1. Furthermore, by providing a gap between the metal member 12 and the aluminum member 11, bimetallic corrosion between the metal member 12 and the aluminum member 11 can be further suppressed.

[0057] (hot crimping) Preferably, the protrusion 111 is hot-caulked. The tip 1112 of the protrusion 111 is a hot-caulked portion. Hot-caulking can prevent the protrusion 111 from cracking during the caulking operation. Furthermore, hot-caulking does not cause work hardening of the tip 1112.

[0058] Whether the manufacturing method of the protrusion 111 is hot crimping or cold crimping can be determined based on the presence or absence of work hardening at the tip 1112. A work-hardened portion is significantly formed at the tip 1112 of the cold crimped protrusion 111. If the hardness H1 of the tip 1112 of the protrusion 111 and the hardness H2 of the aluminum member 11 at a location 10 mm or more away from the protrusion 111 satisfy H1≦1.1×H2, the protrusion 111 is considered to have been hot crimped.

[0059] The hardness H1 of the tip 1112 of the protrusion 111 is measured on a cross section of the protrusion 111. The cross section passes through approximately the center of the protrusion 111 and is parallel to the surface of the aluminum member 11. The maximum value of the Vickers hardness measured at any five points on the cross section of the tip 1112 of the protrusion 111 is regarded as H1.

[0060] The hardness H2 of the aluminum member 11 is measured in a cross section perpendicular to the surface of the aluminum member 11. The "surface" refers to the surface on which the protrusions 111 are provided. The measurement position for H2 is any point that satisfies the following requirements. (1) The center of the thickness of the aluminum member 11 or a position at a depth equivalent thereto. (2) A position 10 mm or more away from the protrusion 111 along the surface of the aluminum member 11. Regarding (1) above, for example, if the aluminum member 11 is a plate-like member with a thickness of t, the measurement position for H2 is set at a depth of t / 2 from the surface of the aluminum member 11. Next, regarding (2) above, for example, when measuring H2 in a cross section that passes through the center of the protrusion 111 and is perpendicular to the surface of the aluminum member 11 as shown in FIG. 1, the measurement position for H2 is set at a distance of 10 mm or more from 1113 to the left of the page. The average value of the Vickers hardness of the aluminum member 11 measured at any five points that satisfy the above requirements is regarded as H2. The test force used in measuring the Vickers hardness is the same for all points.

[0061] (2. Method for manufacturing the bonded structure 1) A manufacturing method of a joined structure 1 according to another embodiment of the present disclosure is a manufacturing method of a joined structure 1 having an aluminum member 11, one or more metal members 12, and an adhesive 13 for bonding the aluminum member 11 and the metal member 12. The manufacturing method includes the steps of applying the adhesive 13 to one or both of the aluminum member 11 having one or more protrusions 111A and the metal member 12 having one or more through holes 121; bonding the aluminum member 11 and the metal member 12 using the adhesive 13 while inserting the protrusions 111A into the through holes 121; deforming the tips of the protrusions 111A to crimp the protrusions 111A into the through holes 121; and curing the adhesive 13. Details of the manufacturing method of the joined structure 1 according to this embodiment are described below. Note that the preferred embodiments of the joined structure 1 described above can also be applied to the manufacturing method of the joined structure 1 according to this embodiment.

[0062] (Aluminum member 11 and metal member 12) In the manufacturing method of the joined structure 1 according to this embodiment, an aluminum member 11 and a metal member 12 are joined. The aluminum member 11 has one or more protrusions 111A. The protrusions 111A before crimping do not have tip portions 1112. The metal member 12 has one or more through holes 121. In the joined structure 1, the protrusions 111A are inserted into the through holes 121. Therefore, the positions of the protrusions 111A and the through holes 121 need to be appropriately selected.

[0063] (S1 Application of adhesive 13) First, as shown in Fig. 5, adhesive 13 is applied to aluminum member 11 and / or metal member 12. Adhesive 13 is applied to the overlapping surfaces of aluminum member 11 and metal member 12. Preferably, adhesive 13 is applied to the periphery of protrusion 111A and / or through hole 121. This results in protrusion 111A and through hole 121 being provided in the adhesive portion.

[0064] (S2 Adhesion of aluminum member 11 and metal member 12) Next, as shown in Fig. 6, the aluminum member 11 and the metal member 12 are bonded together. At this time, as shown in Fig. 6, the protrusion 111A of the aluminum member 11 is inserted into the through-hole 121. The bonding is performed by pressing the area of ​​one member to which the adhesive 13 is applied against the surface of the other member. Furthermore, in parallel with the bonding operation, the protrusion 111A is inserted into the through-hole 121.

[0065] (S3 Deformation of the tip of the protrusion 111A) To ensure the bonding strength between the aluminum member 11 and the metal member 12, it is essential to harden the adhesive 13. However, in the manufacturing method of the joined structure 1 according to this embodiment, before hardening the adhesive 13, the tip of the protrusion 111A is deformed as shown in FIG. 7 or 8. This causes the protrusion 111A to be crimped into the through hole 121. By crimping the protrusion 111A into the through hole 121, a tip 1112 is formed, and the aluminum member 11 and the metal member 12 are temporarily fixed together.

[0066] Preferably, when deforming the tip of protrusion 111A, protrusion 111A is heated. This softens protrusion 111A and reduces deformation resistance. The reduced deformation resistance prevents protrusion 111A from cracking during crimping.

[0067] A suitable example of a heating means for the protrusion 111A is a spot welding electrode 2. The spot welding electrode 2 is a rod-shaped electrode made of a copper alloy that, during spot welding, directly contacts the base material to pass a welding current and transmit a pressing force. However, in the manufacturing method for the joined structure 1 according to this embodiment, the spot welding electrode 2 is not used to weld the metal member 12 and the aluminum member 11. The spot welding electrode 2 applies pressure to the protrusion 111A while passing current through it. The resistance heat generated by the current passing through the electrode 2 causes the protrusion 111A to be thermally softened. By applying pressure to the protrusion 111A in its thermally softened state, the tip of the protrusion 111A is easily deformed, forming a tip 1112 that crimps the through hole 121.

[0068] The crimping of the protrusion 111A using the spot welding electrode 2 may be performed using either a direct spot welding machine or an indirect spot welding machine. JIS Z 3001-6:2013, "Welding Terminology - Part 6: Resistance Welding," defines direct spot welding as spot welding performed by applying pressure directly to the weld joint with an electrode and passing a welding current in the plate thickness direction. In this standard, indirect spot welding is defined as spot welding in which a current is passed through the electrode in a manner similar to series current, creating a single nugget in the base material directly below the electrode. Below, specific examples of crimping performed using a direct spot welding machine or an indirect spot welding machine are described.

[0069] (Crimping work using a direct spot welder) When crimping the protrusion 111A using a direct spot welding machine, as illustrated in FIG. 7 , the protrusion 111A is sandwiched between a pair of spot welding electrodes 2. The tip of one of the spot welding electrodes 2 is placed at the tip of the protrusion 111A. The tip of the other spot welding electrode 2 is placed on the surface of the aluminum member 11 opposite the protrusion 111A. The central axes of the pair of spot welding electrodes 2 are aligned. Then, while a current is passed between the pair of spot welding electrodes 2, the spot welding electrodes 2 are moved to narrow the distance between the electrodes. This crushes the tip of the protrusion 111A, forming a tip portion 1112 having a diameter larger than that of the through hole 121.

[0070] (Crimping work using an indirect spot welder) When crimping the protrusion 111A using an indirect spot welding machine, a pair of spot welding electrodes 2 are arranged in parallel, as illustrated in FIG. 8 . The tip of one of the spot welding electrodes 2 is placed at the tip of the protrusion 111A. The tip of the other spot welding electrode 2 is placed on the surface of the aluminum member 11 on which the protrusion 111A is provided. The central axes of the pair of spot welding electrodes 2 do not coincide. Then, while a current is passed between the pair of spot welding electrodes 2, the spot electrode placed at the tip of the protrusion 111A is pressed against the protrusion 111A. This crushes the tip of the protrusion 111A, forming a tip portion 1112 having a diameter larger than that of the through hole 121.

[0071] Crimping using a direct spot welder is preferable because it can be performed easily and reliably. However, when performing crimping using a direct spot welder, it is necessary to place the spot welding electrode 2 on the surface of the aluminum member 11 opposite the protrusion 111A. For example, if the aluminum member 11 has a closed cross-sectional structure, crimping using a direct spot welder may not be possible. Crimping using an indirect spot welder is suitable for such cases because, when performing crimping using an indirect spot welder, both of the pair of spot welding electrodes 2 are placed on the surface on which the protrusion 111A is provided.

[0072] (S4 Curing of adhesive 13) After the aluminum member 11 and the metal member 12 are temporarily joined, the adhesive 13 is cured. The specific means for curing the adhesive 13 is selected depending on the type of adhesive 13. For example, if the adhesive 13 is a thermosetting adhesive, the adhesive 13 is heated. For example, as shown in FIG. 9, the temporarily joined aluminum member 11 and the metal member 12 can be placed in a heating furnace to cure the thermosetting adhesive. Preferably, the heating temperature (140°C to 190°C) used in the baking process of electrodeposition coating for automobiles is utilized. Once the curing of the adhesive 13 is complete, a joined structure 1 is obtained, which includes the aluminum member 11, one or more metal members 12, and the adhesive 13 that joins the aluminum member 11 and the metal member 12.

[0073] A curing time of several minutes to several hours is required for the adhesive 13 to completely harden. Until the curing is complete, the aluminum member 11 and the metal member 12 must be held in a state in which their bonding surfaces are pressed together. However, in the manufacturing method of the joined structure 1 according to this embodiment, temporary fastening using secondary materials such as self-piercing rivets, bolts, and FDS is not required. This is because temporary fastening using the protrusions 111 and the through holes 121 is completed when the aluminum member 11 and the metal member 12 are bonded together.

[0074] (Action and effect) In the manufacturing method of the joined structure 1 according to this embodiment, the aluminum member 11 and the metal member 12 can be temporarily joined using the protrusion 111 provided on the aluminum member 11 and the through hole 121 provided on the metal member 12. Therefore, the manufacturing method of the joined structure 1 according to this embodiment does not require secondary materials such as self-piercing rivets, bolts, or FDS when curing the adhesive 13. Furthermore, in the manufacturing method of the joined structure 1 according to this embodiment, the protrusion 111A is crimped into the through hole 121 using a spot welding machine having a spot welding electrode 2. Therefore, the manufacturing method of the joined structure 1 according to this embodiment can temporarily join the aluminum member 11 and the metal member 12 using a spot welding machine, which is a general-purpose equipment. By not using secondary materials and using general-purpose equipment, the joined structure 1 can be manufactured inexpensively. In addition, in the manufacturing method of the joined structure 1 according to this embodiment, the protrusion 111A is crimped in a thermally softened state. Therefore, the manufacturing method of the joined structure 1 according to this embodiment can suppress cracking of the aluminum member 11 having the protrusion 111 provided therein.

[0075] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited thereto and can be appropriately modified without departing from the technical spirit thereof. A more preferred example of the joined structure 1 according to the present embodiment and the method for manufacturing the same will be described below.

[0076] (Diameter and depth of through-hole 121) The diameter of the through hole 121 provided in the metal member 12 is preferably, for example, 3.0 to 25.0 mm. The diameter of the through hole 121 refers to the diameter of the through hole 121 when the through hole 121 is circular, and refers to the maximum diameter when the through hole 121 is elliptical or polygonal. When the through hole 121 has a tapered shape, it is preferable that the maximum and minimum diameters of the through hole 121 are within the above-mentioned ranges.

[0077] The larger the through hole 121, the easier it is to insert the protrusion 111A into the through hole 121. Furthermore, the larger the through hole 121, the thicker the diameter of the shaft 1111, which ensures the bonding strength, can be made. This increases the bonding strength during temporary fastening and reduces the risk of the temporary fastening portion coming loose. On the other hand, the smaller the through hole 121, the thinner the protrusion 111 can be made. This makes it easier to deform the protrusion 111A. Note that the bonding portion formed by the through hole 121 and the protrusion 111 only needs to have a bonding strength sufficient to temporarily fasten the metal member 12 and the aluminum member 11. Therefore, the diameter of the through hole 121 may be small.

[0078] The depth of the through hole 121 can be selected appropriately depending on the shape of the metal member 12. The depth of the through hole 121 is the same as the thickness of the metal member 12 at the position where the through hole 121 is provided. From the viewpoint of facilitating the crimping operation, the depth of the through hole 121 is preferably 5.0 mm or less. From the viewpoint of ensuring temporary fastening strength, the depth of the through hole 121 is preferably 0.6 mm or more. When the metal member 12 is plate-shaped, the through hole 121 can be provided at any position in the metal member 12. On the other hand, when the metal member 12 is non-plate-shaped, a plate-shaped flange portion can be provided on the metal member 12, and the through hole 121 can be provided in the flange portion.

[0079] (Diameter of shaft 1111 of protrusion 111) In the joined structure 1, the maximum diameter of the shank 1111 of the protrusion 111 provided on the aluminum member 11 may be the same as the diameter of the through hole 121. This is because the diameter of the shank 1111 expands when the tip of the protrusion 111 is deformed. However, as shown in the cross-sectional photograph of FIG. 2 and the schematic diagram of FIG. 3, adhesive 13 may be disposed between the shank 1111 and the inner wall of the through hole 121. Therefore, the diameter of the shank 1111 of the protrusion 111 may be smaller than the diameter of the through hole 121. In the joined structure 1, preferred examples of the diameter and length of the shank 1111 of the protrusion 111 correspond to the diameter and depth of the through hole 121 described above.

[0080] The diameter of protrusion 111A before the tip is deformed is preferably 0.3 mm or more smaller than the diameter of through hole 121. This makes it easier to insert protrusion 111A into through hole 121. More preferably, the diameter of protrusion 111A before the tip is deformed is 0.5 to 2.5 mm smaller than the diameter of through hole 121. This allows adhesive 13 to flow between protrusion 111A and through hole 121. Adhesive 13 disposed between protrusion 111A and through hole 121 further suppresses bimetallic corrosion between metal member 12 and aluminum member 11. Note that the diameter of protrusion 111A refers to the diameter when the cross-sectional shape of protrusion 111A is circular, and refers to the maximum diameter when the cross-sectional shape of protrusion 111A is elliptical or polygonal.

[0081] (Protrusion amount of protrusion 111A before deformation of the tip) The protrusion amount of the protrusion 111A before the tip is deformed is preferably 3.0 to 15.0 mm. The protrusion amount is the distance between the surface of the metal member 12 that is not in contact with the aluminum member 11 and the tip of the protrusion 111A when the protrusion 111A before the tip is deformed is inserted into the through hole 121. If the metal member 12 and the aluminum member 11 come into contact around the protrusion 111A when the protrusion 111A is inserted into the through hole 121, the protrusion amount of the protrusion 111A is the length of the protrusion 111A minus the depth of the through hole 121. If a gap is formed between the metal member 12 and the aluminum member 11 around the protrusion 111A when the protrusion 111A is inserted into the through hole 121 as illustrated in FIG. 4, the protrusion amount of the protrusion 111A is the length of the protrusion 111A minus the depth of the through hole 121 and the thickness of the gap.

[0082] Note that when measuring the protrusion amount of protrusion 111A before deforming the tip, adhesive 13 is not applied. That is, the thickness of adhesive 13 is not taken into consideration when determining the protrusion amount of protrusion 111A before deforming the tip. This is because the thickness of adhesive 13 varies depending on the pressure applied when bonding metal member 12 and aluminum member 11.

[0083] The smaller the protrusion amount, the easier it is to deform the tip of protrusion 111A, whereas the greater the protrusion amount, the larger the diameter of tip 1112, and the stronger the temporary fastening strength.

[0084] (Shape of tip 1112) The diameter of the tip portion 1112 is preferably 1.5 mm or more larger than the diameter of the through hole 121. The diameter of the tip portion 1112 refers to the diameter of the tip portion 1112 when the tip portion 1112 is circular when viewed in a plane along the axial direction of the through hole 121, and refers to the maximum diameter when the tip portion 1112 is elliptical or polygonal. The thickness of the tip portion 1112 is preferably 1.0 to 9.0 mm. The thickness of the tip portion 1112 refers to the distance between the surface of the metal member 12 and the tip of the protrusion 111 in the joined structure 1.

[0085] The larger the diameter and thickness of the tip portion 1112, the stronger the temporary fastening strength. The smaller the diameter and thickness of the tip portion 1112, the easier it is to deform the tip of the protrusion 111.

[0086] (Adhesive 13) There is no particular limitation on the type of adhesive 13. Suitable examples of the adhesive 13 include structural epoxy adhesives, rubber adhesives, and urethane adhesives. Alternatively, a structural adhesive that combines epoxy and rubber and has excellent vibration damping properties may be used. [Explanation of symbols]

[0087] 1 Joined structure 11 Aluminum components 111 Protrusion 111A Protrusion before crimping 1111 Shaft 1112 Tip 1113 Proximal end 12 Metallic parts 121 Through hole 13 Adhesive 2 Spot welding electrodes

Claims

1. Aluminum members, one or more metal members; an adhesive for joining the aluminum member and the metal member; A joint structure comprising: The aluminum member has one or more protrusions, the metal member has one or more through holes; the protrusion is inserted into the through hole and is crimped; the adhesive is disposed between the protrusion and the inner wall of the through hole; The hardness H1 of the tip of the protrusion and the hardness H2 of the aluminum member at a location 10 mm or more away from the protrusion satisfy H1≦1.1×H2. bonded structure.

2. 2. The joined structure according to claim 1, wherein the aluminum member is an aluminum die-cast member.

3. 3. The joined structure according to claim 2, wherein the protrusions of the aluminum member are formed during die casting.

4. 4. The joint structure according to claim 1, wherein the metal member is a plated steel material.

5. 5. The joint structure according to claim 4, wherein the plated steel material is an aluminum-based plated steel material or a zinc-based plated steel material.

6. 4. The joint structure according to claim 1, wherein the metal member is a painted steel material or a chromate-free treated steel material.

7. 4. The joined structure according to claim 1, wherein the material of the metal member is an aluminum alloy.

8. The joint structure according to claim 1, characterized in that one or both of the through hole and the protrusion inserted into the through hole have a tapered shape that narrows from the base end of the protrusion toward the tip.

9. 4. The joint structure according to claim 1, wherein the cross-sectional area of ​​the base end of the protrusion is larger than the area of ​​the through hole on the side facing the aluminum member.

10. A method for manufacturing a joined structure having an aluminum member, one or more metal members, and an adhesive that joins the aluminum member and the metal member, comprising: applying the adhesive to one or both of the aluminum member having one or more protrusions and the metal member having one or more through holes; a step of adhering the aluminum member and the metal member using the adhesive while inserting the protrusion into the through hole; a step of deforming a tip of the protrusion to crimp the protrusion into the through hole; curing the adhesive; Equipped with The adhesive is disposed between the protrusion and the inner wall of the through hole; The protrusion is heated when the protrusion is caulked into the through hole. A method for manufacturing a bonded structure.

11. The method for manufacturing a joint structure according to claim 10, wherein the protrusion is heated and the tip of the protrusion is deformed using a spot welding electrode.

Images