JP2023016355A - Joint method - Google Patents

Abstract

To provide a joint method that can achieve a joint body with high joint strength.SOLUTION: The joint method includes steps of: forming an uneven shape, in which a ratio of a depth from a tip portion of a convex part to a base end part thereof and a width of the tip portion of the convex part is 10:1 or more, in a first metal member; and jointing the first metal member to a second metal member by giving vibrations along a protruding direction of the convex part to the first metal member while pressurizing the first metal member and the second metal member which are superposed on each other, with the tip portion of the convex part in the uneven shape contacted with a portion to be jointed of the second metal member, along the protruding direction of the convex part.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a joining method, and more particularly to a joining method using frictional heat.

2. Description of the Related Art A technique is known in which metal members are joined together in a solid phase state by utilizing frictional heat generated by rubbing metal members against each other at high speed.

Patent Document 1 discloses a welded structure made of an aluminum alloy, in which part or all of the welded structure is made of an aluminum alloy containing 0.4 to 0.9% Si and 0.4 to 1.2% Mg by weight. Disclosed is a welded structure characterized in that it consists of two parts and is joined by friction welding.

JP-A-11-5180

In the technique described in Patent Document 1, friction welding is performed by butting metal members together. However, in the case of such a joining method, since the contact area between metal members is large, when joining metal members with high thermal conductivity such as aluminum alloys, frictional heat is likely to be transmitted to areas other than the joining interface. Therefore, with the technique described in Patent Document 1, there is a problem that heat generation at the bonding interface is insufficient, and sufficient bonding strength may not be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is an object of the present invention to provide a bonding method capable of obtaining a bonded body having a high bonding strength.

In the joining method according to one embodiment, the concave-convex shape is formed on the first metal member such that the ratio of the depth from the distal end to the proximal end of the projection to the width of the distal end of the projection is 10:1 or more. and a direction in which the protrusions project from the first metal member and the second metal member, which are superimposed with the tips of the protrusions having an uneven shape in contact with the joined portion of the second metal member. and bonding the first metal member to the second metal member by applying vibration along the direction in which the projection protrudes to the first metal member while applying pressure along the .

ADVANTAGE OF THE INVENTION By this invention, the joining method by which the joined body of high joint strength is obtained can be provided.

4 is a flow chart showing a joining method according to the first embodiment; It is a figure explaining step S1 of the flowchart shown in FIG. FIG. 3 is a partially enlarged view of FIG. 2; FIG. 2 is a first diagram illustrating step S2 in the flowchart shown in FIG. 1; FIG. 2 is a second diagram illustrating step S2 in the flowchart shown in FIG. 1; 10A and 10B are diagrams for explaining a bonding method of Comparative Example 1; FIG. 8A and 8B are diagrams for explaining a bonding method of Comparative Example 2; FIG.

Embodiment 1
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings have been simplified as appropriate. Furthermore, in the following description, the same or equivalent elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

First, with reference to FIG. 1, the outline of the joining method according to this embodiment will be described. FIG. 1 is a flow chart showing a joining method according to a first embodiment. As shown in FIG. 1, the bonding method according to the present embodiment includes a step S1 of forming an uneven shape on the first metal member 10 and a step S2 of bonding the first metal member 10 to the second metal member 20. have a process.

In the bonding method according to the present embodiment, the first metal member 10 and the second metal member 20 are bonded together by using frictional heat generated at the bonding interface by rubbing the first metal member 10 and the second metal member 20 together at high speed. A conjugate bonded in a solid state can be obtained. First, the first metal member 10 and the second metal member 20, which are members to be joined, will be described.

The material forming the first metal member 10 and the second metal member 20 is, for example, a metal whose main component is aluminum, which is lightweight and has good thermal conductivity. That is, the first metal member 10 and the second metal member 20 are metal members each made of aluminum or an aluminum alloy. In this embodiment, a case of joining materials to be joined (the first metal member 10 and the second metal member 20) made of an aluminum alloy will be described as an example.

Specifically, in this embodiment, the first metal member 10 is an extruded aluminum profile, and the second metal member 20 is a die-cast aluminum casting member. Also, the first metal member 10 and the second metal member 20 are each formed in a plate shape. However, the shapes of the first metal member and the second metal member are not limited to this. The shape of the first metal member and the second metal member may be at least partially plate-like, and each may take any shape such as a square tubular shape as a whole.

A joined body obtained by using the joining method according to the present embodiment can be used as a member constituting a body frame of a vehicle such as an automobile. When the joined body is applied to such a large machine part, the weight can be reduced by making it made of aluminum, which contributes to the improvement of the ride comfort of the vehicle and the improvement of the heat and electricity costs of the vehicle.

Next, a specific example of the joining method according to this embodiment will be described with reference to FIGS. 2 to 5. FIG. First, step S1 will be described with reference to FIG. FIG. 2 is a diagram for explaining step S1 in the flow chart shown in FIG.

In joining the first metal member 10 and the second metal member 20, in step S1, the depth from the tip end portion 12a to the base end portion 12b of the projection 12 on the first metal member 10 and the depth of the projection 12 A concave-convex shape having a ratio of 10:1 or more to the width of the tip portion 12a is formed.

The first metal member 10 shown in FIG. 2 has nano-order fine irregularities formed in the joined portion 13 to be joined to the second metal member 20 . In this way, the first metal member 10 formed with an uneven shape has a plate-like body portion 11 and a convex portion 12 projecting outward from the body portion 11 . In the following description, the direction along the direction in which the convex portion 12 protrudes is defined as the X-axis direction.

A plurality of protrusions 12 are formed along the length direction of the first metal member 10 orthogonal to the X-axis direction. Such an uneven shape can be formed using methods such as profile processing and chemical conversion treatment. However, the method of forming the uneven shape on the first metal member 10 is not limited to these methods.

Next, details of the convex portion 12 will be described with reference to FIG. 3 is a partially enlarged view of FIG. 2. FIG. As shown in FIG. 3, the convex portion 12 is located on the opposite side of the base end portion 12b that is farther from the main body portion 11 than the cross-sectional area of the base end portion 12b located on the main body portion 11 side when viewed in the X-axis direction. It is formed so that the cross-sectional area of the located tip portion 12a is small. In this embodiment, the convex portion 12 has a tapered shape in which the cross-sectional area viewed from the X-axis direction gradually decreases from the base end portion 12b toward the tip portion 12a.

Further, the tip portion 12a of the convex portion 12 has a flat portion facing the second metal member 20. As shown in FIG. As a result, the stress generated in the tip portion 12a due to the pressure and vibration applied to the first metal member 10 is reduced, so that damage to the convex portion 12 can be suppressed. The shape of the portion of the distal end portion 12a that faces the second metal member 20 is not limited to being flat, and may be curved, for example.

Furthermore, the plurality of protrusions 12 may be formed continuously in the length direction of the first metal member 10, or may be formed at predetermined intervals from each other. Both ends of the base end portion 12b are formed in an R shape in the width direction of the protrusion 12 perpendicular to the X-axis direction. As a result, the stress generated in the base end portion 12b due to the pressure and vibration applied to the first metal member 10 is reduced, and breakage of the convex portion 12 can be suppressed.

The convex portion 12 has dimensions of a depth D1, a width W1 of the distal end portion 12a, and a width W2 of the proximal end portion 12b. The depth D1 is the length from the distal end portion 12a to the proximal end portion 12b of the convex portion 12 along the X-axis direction. Further, the width W1 is the length of the tip portion 12a in the width direction of the convex portion 12 perpendicular to the X-axis direction. Further, the width W2 is the length of the base end portion 12b in the width direction of the convex portion 12 orthogonal to the X-axis direction.

When the ratio of the depth D1 to the width W1 (D1:W1) is preferably 10:1 or more, more preferably 20:1 or more, and still more preferably 25:1 or more, a bonded body with a good bonding state can be obtained. be able to.

For example, the projection 12 shown in FIGS. 2 and 3 has a depth D1 of 500 nm, a width W1 of 20 nm, and a width W2 of 100 nm. That is, D1:W1 is 25:1. Further, the length in the width direction of the convex portion 12 gradually decreases from the base end portion 12b toward the tip portion 12a so that W1:W2 is 1:5. From the viewpoint of concentrating the vibration energy during bonding, it is preferable to design the ratio of the width W1 and the width W2 so that the contact area of the first metal member 10 with the second metal member 20 is as small as possible. In the example shown in FIGS. 2 and 3 , the projections 12 of D1:W1:W2=25:1:5 are formed continuously in the length direction of the first metal member 10 .

Next, step S2 will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a first diagram for explaining step S2 of the flow chart shown in FIG. FIG. 5 is a second diagram for explaining step S2 of the flow chart shown in FIG.

In step S2, the first metal member and the second metal member are overlapped with the tip portion 12a of the protrusion 12 formed in step S1 in contact with the joined portion 21 of the second metal member 20. As shown in FIG. Here, the joined portion 21 of the second metal member 20 is a portion to be joined to the first metal member 10 . Then, the first metal member 10 and the second metal member that are overlapped are pressed along the direction in which the protrusions 12 protrude, and vibration is applied to the first metal member 10 along the direction in which the protrusions 12 protrude. . Thereby, the first metal member 10 is joined to the second metal member 20 .

As a bonding device for bonding the first metal member 10 and the second metal member 20, for example, an ultrasonic bonding machine or a vibration welding machine can be applied. Such a joining device includes a pressurizing device for pressurizing the superimposed first and second metal members, a vibrating body 40 for vibrating the first metal member, and a support for supporting the second metal member. a member 30; A vibrating device is connected to the vibrating body 40 .

The joining apparatus brings the metal members to be joined into contact with each other, applies pressure to the joint interface and applies vibration to the joint interface, and utilizes frictional heat generated to solid-state join the metal members. The joining apparatus rubs the metal members together at high speed to remove the oxide film and the like on the joining interface to expose the new surface, and can join the metal members in a solid phase state by plastic flow accompanying pressurization. .

Ultrasonic vibration or sonic vibration can be used as the vibration applied when the first metal member 10 and the second metal member 20 are joined. In the case of ultrasonic vibration, the bonding apparatus applies ultrasonic vibration of about 15 to 50 kHz to the first metal member 10 through the vibrating body 40 . In the case of sonic vibration, the bonding apparatus applies sonic vibration with a large amplitude of about 100 to 300 Hz to the first metal member 10 via the vibrating body 40 . The vibrating body 40 vibrates vertically by resonating with ultrasonic vibrations or sonic vibrations transmitted from the vibrator of the vibrating device.

For example, the joining of the first metal member 10 and the second metal member 20 is performed as follows. First, as shown in FIG. 4, the first metal member 10 and the second metal member 20 are sandwiched between the vibrating body 40 and the support member 30 of the bonding apparatus and pressed.

When the material to be welded is sandwiched between the vibrating body 40 and the support member 30, the first metal member 10 and the second metal member 20 are overlapped so that the tip portion 12a abuts on the portion to be welded 21, and the second metal member 10 and the second metal member 20 are overlapped. The metal member 20 is placed on the support member 30 . The joined portion 21 of the second metal member 20 is formed flat, for example, and arranged horizontally when placed on the support member 30 . Therefore, the first metal member 10 is arranged so that the projecting direction of the convex portion 12 is downward in the vertical direction when the first metal member 10 is joined.

Subsequently, the material to be joined is pressed vertically (X-axis direction) by the vibrating body 40 and the support member 30 . In this embodiment, the vibrating body 40 is pressed from above the first metal member 10 by a pressurizing device and pressurized in the direction of the white arrow in FIG. 4 with a predetermined load.

Furthermore, in this pressurized state, by applying vibration in the vertical direction (X-axis direction) to the first metal member 10, frictional heat is generated at the joint interface between the convex portion 12 and the joint portion 21 that are rubbed together. Let Since the convex portion 12 is formed so that the cross-sectional area of the tip portion 12a is smaller than that of the base end portion 12b, the vibration energy applied to the first metal member 10 concentrates on the tip portion 12a. The tip portion 12a where vibration energy concentrates locally generates heat due to frictional heat. Moreover, since the contact area of the first metal member 10 with respect to the second metal member 20 is small, even if a metal with high thermal conductivity is used as the material of the material to be joined, frictional heat is less likely to be transmitted to areas other than the joining interface. As a result, the temperature of the bonding interface rises to the temperature necessary for bonding in a short period of time.

In this step, since the first metal member 10 is vibrated in the vertical direction parallel to the X-axis direction, the fine projections 12 are affected more than when vibration is applied in the horizontal direction perpendicular to the X-axis direction. Stress is reduced, and breakage of the convex portion 12 can be suppressed. In addition, the conditions of the joining apparatus are appropriately set according to the shapes and materials of the first metal member 10 and the second metal member 20, the area of the joining interface, and the like.

Then, as shown in FIG. 5, the oxide film on the metal surface is destroyed by the friction phenomenon at the joint interface to which the vibration is applied, and plastic flow occurs due to the pressurization. In addition, since frictional heat locally raises the temperature of the tip side of the protrusion 12, the temperature of the bonding interface rises in a short time, promoting diffusion and recrystallization of atoms. As a result, the protrusions are deformed so as to melt, and a planar joint portion is formed in which the joint portion 13 of the first metal member 10 and the joint portion 21 of the second metal member 20 are joined in a good solid phase state. It is formed. In this manner, a joined body in which the first metal member 10 and the second metal member 20 are metallurgically joined can be manufactured.

Here, the case where the uneven shape is not formed on the first metal member 10 will be described with reference to FIG. 6A and 6B are diagrams for explaining the bonding method of Comparative Example 1. FIG. As shown in FIG. 6, in the joining method of Comparative Example 1, the plate-shaped metal member 100 is joined to the second metal member 20 using the joining apparatus described with reference to FIG.

The metal member 100 corresponds to the first metal member 10 before forming the uneven shape. The metal member 100 has a flat joined portion 101 to be joined with the second metal member 20 . The second metal member 20 also has a flat joined portion 21 to be joined to the metal member 100 .

When the metal member 100 and the second metal member 20 are joined together, the metal member 100 and the second metal member 20 are overlapped so that the joined portion 101 abuts against the joined portion 21, and the vibrating body 40 and the supporting member 20 are supported. It is sandwiched between the member 30 and applies vibration to the metal member 100 while applying pressure from above and below.

According to the bonding method of Comparative Example 1, since the contact area of the metal member 100 with respect to the second metal member 20 is large, frictional heat during bonding is diffused and transmitted to areas other than the bonding interface, and the heat is easily dissipated from the metal member 100. . In this case, heat generation at the bonding interface becomes insufficient, and there is a possibility that sufficient bonding strength cannot be obtained. Such a phenomenon can be particularly problematic when joining aluminum or aluminum alloys with high thermal conductivity.

As another joining method using frictional heat, the joining method of Comparative Example 2 shown in FIG. 7 can be considered. 7A and 7B are diagrams for explaining the joining method of Comparative Example 2. FIG. As shown in FIG. 7, the joining method of Comparative Example 2 shows a method of joining the first metal member 10 and the second metal member 20 having an uneven shape by spin welding.

In the case of spin welding shown in FIG. 7, a first metal member 10 and a second metal member 20 are held so that the to-be-bonded portion 13 and the to-be-bonded portion 21 face each other in the X-axis direction, and the first metal member 10 is rotated around the X-axis at a high speed and lowered toward the second metal member 20 while being pressurized. Spin welding is a joining method in which the first metal member 10 rotating at high speed is pressed against the second metal member 20, and solid state joining is performed using frictional heat generated at the joining interface.

However, according to the joining method of Comparative Example 2, due to the rotation of the first metal member 10, the fine projections 12 are twisted and stress is concentrated near the tip 12a, so that the projections 12 are easily broken and damaged. there is a possibility. Therefore, as a method of joining the first metal member 10 having the uneven shape to the second metal member 20, spin welding, which rotates the material to be joined around the X-axis, is not preferable.

Fusion welding such as arc welding, gas welding, laser welding, or electron beam welding can be cited as other joining methods for metallurgically joining metal members.

However, die-cast aluminum casting members contain hydrogen gas inside due to the characteristics of the manufacturing method. For this reason, when joining cast aluminum members by fusion welding, the hydrogen gas inside the cast aluminum members becomes a blow hole and remains in the joint as a result of melting the cast aluminum member with a high heat input, resulting in internal defects. can occur. If blowholes remain in the joint, the joint area is reduced, and sufficient joint strength cannot be obtained. Thus, the die-cast aluminum casting member has a problem that fusion welding is difficult.

Furthermore, when dissimilar metals are joined by fusion welding, a weak intermetallic compound is formed at the joining interface between metal members made of dissimilar metals, so there is a problem that the joining strength is reduced.

On the other hand, in solid-state welding, in which the amount of heat input to the materials to be joined is smaller than that in fusion welding, metal members can be joined without melting, so that blowholes do not occur and the formation of intermetallic compounds is suppressed. Therefore, the bonding strength is less likely to be lowered due to thermal effects. Solid-state bonding can be used to bond materials in a solid state without melting them, so that it is suitable for bonding metals of the same kind, such as aluminum alloys, and metals of different kinds.

When solid-phase bonding with such advantages is applied to large machine parts, the amount of heat input from frictional heat is smaller in bonding methods that generate frictional heat due to vibration, such as ultrasonic bonding, compared to spin welding, etc. , there is a problem that the temperature of the junction interface is difficult to rise. If the heat generated at the bonding interface is insufficient for the temperature required for bonding, the bonding strength of the bonding portion will decrease. Therefore, in order to improve the joint strength of the joint, the temperature of the joint interface must be sufficiently high.

In order to solve these problems, the joining method according to the present embodiment provides the first metal member 10 with the depth from the tip 12a to the base 12b of the protrusion 12 and the width of the tip 12a of the protrusion 12. a step of forming an uneven shape with a ratio of 10:1 or more; While pressing the member and the second metal member along the direction in which the protrusions 12 protrude, vibration is applied to the first metal member 10 along the direction in which the protrusions 12 protrude, thereby moving the first metal member 10 to the second position. and bonding to two metal members 20 .

With such a configuration, the vibration energy applied during bonding concentrates on the tip portion 12a of the convex portion 12. As shown in FIG. In addition, the contact area between the first metal member 10 and the second metal member 20 during bonding is reduced, and transmission of frictional heat to areas other than the bonding interface is suppressed. Therefore, the temperature of the joint interface can be efficiently raised, and the joint can be formed before frictional heat escapes from the joint interface. Furthermore, since pressure and vibration are applied to the first metal member 10 along the direction in which the protrusions 12 protrude, the stress applied to the protrusions 12 is reduced. As a result, damage to the convex portion 12 can be suppressed.

Moreover, in the above joining method, the first metal member 10 is a metal member made of aluminum or an aluminum alloy. A metal member made of aluminum or an aluminum alloy has high thermal conductivity and large latent heat. Therefore, by applying the bonding method according to the present embodiment, the temperature of the bonding interface can be increased more efficiently.

Moreover, in the joining method, the second metal member 20 is an aluminum cast member made of aluminum or an aluminum alloy. According to the joining method of the present embodiment, since the cast aluminum members are joined in a solid state without being melted, blowholes do not occur and reduction in joint strength can be suppressed.

In addition, in the joining method described above, the tip portion 12a of the convex portion 12 of the first metal member 10 is formed flat. As a result, the pressure applied to the first metal member 10 at the time of bonding and the stress generated in the tip portion 12a due to vibration are reduced, so damage to the convex portion 12 can be suppressed.

As described above, according to the joining method according to the present embodiment, a joined body with high joining strength can be obtained.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention. In the above embodiment, the case of joining metal members made of the same kind of metal containing aluminum as a main component has been described, but the material forming the first metal member 10 and the second metal member 20 is not limited to this.

As a material for forming the first metal member 10 and the second metal member 20, copper, a copper alloy, iron, steel, stainless steel, or the like can be used in addition to a metal containing aluminum as a main component. Moreover, the combination of the first metal member 10 and the second metal member 20 may be made of the same kind of metal, or may be made of different metals.

For example, a combination of a metal member composed of a metal containing aluminum as a main component and a metal member containing iron as a main component, and a metal member containing a metal containing aluminum as a main component and a metal containing copper as a main component It can be applied to joining dissimilar metals such as a combination of members. When applied to the joining of metal members made of dissimilar metals, the formation of an intermetallic compound at the joint interface between the metal members can be suppressed, so that a joined body with high joint strength can be obtained.

10 First metal member 11 Main body 12 Convex part 12a Tip part 12b Base end part 13 Part to be joined 20 Second metal member 21 Part to be joined 30 Support member 40 Vibrating body 100 Metal member 101 Part to be joined

Claims (4)

forming an uneven shape on the first metal member such that the ratio of the depth from the tip to the base of the protrusion to the width of the tip of the protrusion is 10:1 or more;
The first metal member and the second metal member, which are superimposed in a state where the tip end portion of the uneven convex portion is in contact with the joined portion of the second metal member, are arranged along the direction in which the convex portion protrudes. joining the first metal member to the second metal member by applying vibration along the direction in which the projection projects to the first metal member while applying pressure;
joining method. The joining method according to claim 1, wherein the first metal member is a metal member made of aluminum or an aluminum alloy. The joining method according to claim 1 or 2, wherein the second metal member is an aluminum cast member made of aluminum or an aluminum alloy. The joining method according to any one of claims 1 to 3, wherein the tip of the projection is formed flat.

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