JPH09122924A - Resistance joining method between different materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by energizing while abutting both tapered faces each other and pressurizing so as to reduce a time required for joining. SOLUTION: Tapered faces 1a, 2a of a pair of female/male are formed to conductive and different kind materials to be joined 1, 2. A thin insert material 3 of plating, etc., is stuck to the tapered face 1a of the material 1 to be joined. By pressurizing while the tapered faces 1a, 2a of the materials 1, 2 to be joined are abutted and by energizing, a boundary is heated/activated to execute joining. A pair of female/male tapered faces can be formed to two steps. Also, One tapered face at least of a pair of female/male is arranged with a contact part to have line contact as viewing from the circumference. Further, a contact face having face contact as viewing from the circumference is formed to one tapered face at least of a pair of female/male. By this method, the materials to be joined have joining strength equivalent to that of base material strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance joining method for joining dissimilar materials having different conductivity to each other by bringing them into contact with each other.

[0002]

2. Description of the Related Art As a resistance joining method between dissimilar materials having conductivity, there is, for example, a diffusion joining method. In this diffusion joining method, a pressure to such an extent that the material is not largely deformed is applied to the joining surface of the material and It is heated to a temperature not exceeding its melting point and is bonded in the solid state by utilizing the diffusion of atoms generated on the bonding surface.

[0003]

It is said that this diffusion bonding method is generally less deformable than the fusion welding method and the like, and is suitable for bonding dissimilar materials. However, in the normal diffusion bonding method, the bonding strength is easily affected by surface cleanliness and surface roughness, and the processing temperature is high just below the melting point of the material to be bonded, so that the bonding strength is high in a vacuum or an inert gas atmosphere. It requires a long processing time.

The present invention has been made in view of the above points, and an object of the present invention is to provide a resistance joining method for bonding different kinds of materials in the air in a short time.

[0005]

In order to solve the above-mentioned problems and to achieve the object, the resistance joining method between different kinds of materials according to the invention of claim 1 is a method in which different kinds of conductive materials to be joined are male and female. It is characterized in that a pair of tapered surfaces are formed, and pressure is applied in a state where the tapered surfaces are in contact with each other, and current is applied to heat and activate the interface to perform bonding.

As described above, the two materials to be joined are brought into contact with each other by the tapered surfaces, and an appropriate pressing force is applied in the axial direction. The pressing force is set to a value within a range in which the electric resistance of the contact surfaces does not vary greatly.
When an optimum value is selected for proper joining of the materials to be joined and then an electric current is applied, the materials to be joined are heated and joined at the contact part because the electrical resistance of the contact part is higher than that inside, The bonding material has a bonding strength equivalent to that of the base material, can be processed in the air, and the time required for bonding is short, resulting in extremely high productivity.

The resistance joining method between dissimilar materials according to the second aspect of the present invention is characterized in that the tapered surfaces forming the male and female pairs are formed in two steps. In this way, the tapered surfaces forming a male and female pair are formed in two steps, and the joining strength of the materials to be joined is increased.

In the resistance joining method between different kinds of materials according to the third aspect of the present invention, at least one taper surface forming the male and female pair,
It is characterized by having a contact portion that makes line contact when viewed from the circumference. In this way, at least one tapered surface forming a male and female pair has a contact portion that makes line contact when viewed from the circumference,
The current density of the contact portion that makes line contact increases, melting easily occurs from this portion, the time required for bonding is shortened, and productivity is extremely good.

According to a fourth aspect of the present invention, there is provided a resistance joining method for dissimilar materials, wherein at least one tapered surface forming the male and female pair is
It is characterized by having a contact portion that makes surface contact when viewed from the circumference. In this way, at least one tapered surface forming a male and female pair has a contact portion that makes surface contact when viewed from the circumference,
The current density of the contact portion which makes surface contact increases, the portion is easily melted from this portion, the time required for bonding is shortened, and the productivity is extremely good.

According to a fifth aspect of the present invention, there is provided a resistance welding method for dissimilar materials, characterized in that the tapered surfaces forming the male and female pairs are set at different taper angles. In this way, the taper surfaces forming the male and female pairs are set to different taper angles, the current density of the line contact portion increases, melting easily occurs from this portion, the time required for joining is shortened, and productivity is extremely good.

In the resistance joining method between different kinds of materials according to the sixth aspect of the invention, a thin insert material is adhered to at least one tapered surface forming the male-female pair by plating or the like, and the joining is carried out by pressurization and the joining is completed. After that, the feature is that the insert material does not remain at the bonding interface.

When an electric current is applied in this manner, the material to be joined heats up at the contact portion because the electrical resistance of the contact portion is larger than that inside, and at this time, the material atoms of both materials are separated between the insert material and the material to be joined. Mutual diffusion occurs, and as a result, an alloy layer is formed near the interface.

According to a seventh aspect of the present invention, there is provided a resistance bonding method between different kinds of materials in which the surface roughness of the tapered surface is adjusted to Ra 0.1 to 10. In this way, the surface roughness of the tapered surface is adjusted to Ra 0.1 to 10, and even if the cleanliness of the surface is poor, it does not affect the bonding strength. Therefore, even if cutting coolant or lubricating oil is attached, cleaning is performed. It is excellent as an in-line joining method that does not require.

The resistance joining method between dissimilar materials according to the eighth aspect of the present invention is characterized in that the as-cast surface state is used for the tapered surface. In this way, the as-cast surface condition is used for the tapered surface, and similarly, even if the cleanliness of the surface is bad, it does not affect the bonding strength, so cleaning is necessary even if cutting coolant or lubricating oil adheres. It is excellent as an in-line joining method.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the resistance joining method between different materials according to the present invention will be described below. FIG. 1 shows the cross-sectional shape of the joint between different materials and the joining process.

In this embodiment, taper surfaces 1a, which form a pair of male and female, are formed on the different kinds of materials 1 and 2 having different conductivity.
2a is formed. A thin insert material 3 is attached to the tapered surface 1a of the material 1 to be bonded by plating or the like. The tapering surfaces 1a and 2a of the materials 1 and 2 to be joined are pressed in a state of being in contact with each other, and an electric current is applied to heat and activate the interface to perform the joining.

The two members to be joined 1 and 2 are tapered surfaces 1a and 2
The contact is made at a, and an appropriate pressure P is applied in the axial direction. The pressing force P is a value within a range in which the electrical resistance of the contact surface does not vary greatly, and an optimum value is selected for proper joining of the materials to be joined 1 and 2. After that, when a direct current is applied, the materials 1 and 2 to be joined generate heat at the contact portions because the electric resistance at the contact portions is larger than that inside. At this time, mutual diffusion of both material atoms occurs between the insert material 3 and the material 2 to be bonded, and as a result, the alloy layer 4 is formed near the interface, and the materials 1 and 2 to be bonded have the same strength as the base metal. Bonding strength can be obtained, treatment can be performed in the air, and the time required for bonding is, for example, 1 second or less, and productivity is extremely good.

If the insert material 3 is selected so as to form a eutectic alloy with the material 2 to be joined,
The alloy layer 4 thus formed preferentially forms a liquid phase in the course of the subsequent temperature rise, and the diffusion reaction is significantly promoted. Since the interface is pressurized, the liquid phase generated in the interface is discharged to the outside as the non-bonding material is plastically deformed as the temperature rises, and this discharging part 5 is removed by machining. It

In this process, the oxide films on the surfaces of the materials to be joined 1 and 2 are destroyed, and at the same time, a direct diffusion reaction occurs between the materials to be joined 1 and the material to be joined 2, and the alloy near the interface is formed. After the layer 4 is formed and the joining is completed, the insert material does not remain at the joining interface.

The taper surfaces 1a, 2 of the materials 1 and 2 to be joined are
The width of the overlapping portion of a depends on the combination of the materials 1 and 2 to be joined and the capacity of the machine used for joining, but it is 0.1 mm to 1 mm.
0 mm is desirable.

FIG. 2 shows a cross-sectional shape and a joining process of a joining portion between different kinds of materials according to another embodiment. In the resistance joining method between dissimilar materials of this embodiment, the tapered surfaces 1a and 2a, which form a male and female pair of the two materials to be joined 1, have bottom surfaces 1a1 and 2a1 and standing surfaces 1.
It has a2 and 2a2, and the tapered surfaces 1a and 2a are formed in two steps. The tapered surfaces 1a and 2a are bottom surfaces 1a1 and 2a.
1 and the standing surfaces 1a2 and 2a2 are set to different taper angles, the angle between the bottom surface 1a1 of the tapered surface 1a and the bottom surface 2a1 of the tapered surface 2a is β, and the standing surface 1a2 and the tapered surface 2a of the tapered surface 1a are The angle formed by the standing surface 2a2 is α
And the angle β is set equal to or smaller than the angle α.

Further, a contact portion 2a3 is formed between the bottom surface 2a1 and the standing surface 2a2 of the material 2 to be joined, and the contact portion 2a3 allows the contact portion 2a3 to be seen from the circumference as shown in FIG. 2 (a). Line contact.

Tapered surfaces 1a and 2 of the materials 1 and 2 to be bonded to each other
Although a is brought into contact with the surface, pressure is applied and electric current is applied to heat and activate the interface for joining, but one tapered surface 2a forming a male-female pair has a contact portion 2a3 which makes line contact when viewed from the circumference. As a result, the current density of the contact portion 2a3 that makes line contact increases, and it becomes easier to melt from this portion.
Since the tapered surfaces 1a and 2a have different taper angles as shown in (d) to (d), the upper and lower portions 4a and 4b are melted and joined while maintaining a line contact state when viewed from the circumference, and the time required for joining is short. It is extremely productive. Further, the tapered surfaces 1a and 2a forming a male-female pair are formed in two steps, so that the bonding strength of the materials 1 and 2 to be bonded is increased.

FIG. 3 shows a cross-sectional shape of a joint between different kinds of materials according to another embodiment. The resistance joining method between different kinds of materials of this embodiment uses a tapered surface 1 which is a male and female pair of two materials 1 and 2 to be joined.
a and 2a are bottom surfaces 1a1 and 2a1 and standing surfaces 1a2 and 2a.
2 and the tapered surfaces 1a and 2a are formed in two steps. The two materials to be joined 1 and 2 are the bottom surface 2a of the tapered surface 2a.
1 and the standing surface 1a2 of the tapered surface 1a are set to different taper angles, and the bottom surface 1a1 of the tapered surface 1a and the standing surface 2a2 of the tapered surface 2a are set to the same taper angle.
Contact portions 1a4 and 2a where a and 2a are in surface contact when viewed from the circumference
Four. The angle between the bottom surface 1a1 of the tapered surface 1a and the bottom surface 2a1 of the tapered surface 2a is β, and the tapered surface 1
The angle between the standing surface 1a2 of a and the standing surface 2a2 of the tapered surface 2a is α, and the angle β is set to be equal to or smaller than the angle α.

The width D of the contact portions 1a4 and 2a4 with which the tapered surfaces 1a and 2a are in surface contact with each other when viewed from the circumference are shown in FIGS.
As shown in (c), the contact area changes depending on the relative positional relationship between the two materials to be joined 1, the contact area changes, the current density of the contact portions 1a4, 2a4 that make surface contact increases, and melting easily occurs from this portion. Therefore, the time required for joining is shortened and the productivity is extremely good.

FIG. 4 shows a sectional shape of a joint between different kinds of materials according to still another embodiment. The resistance joining method between dissimilar materials of this embodiment is formed in the same manner as in the embodiment of FIG. 2, but the taper surface 1a rises from the angle β formed by the bottom surface 1a1 of the taper surface 1a and the bottom surface 2a1 of the taper surface 2a. The angle α formed by the surface 1a2 and the standing surface 2a2 of the tapered surface 2a is set to be the same or small, the distance L1 between the standing surface 1a2 and the standing surface 2a2 becomes extremely close, and the current flows predominantly. And the lower portion 2a6 of the standing surface 2a2 of the material 2 to be welded is easily melted.

On the other hand, in the embodiment shown in FIG. 2, as shown in FIG. 5, the angle β between the bottom surface 1a1 of the tapered surface 1a and the bottom surface 2a1 of the tapered surface 2a is the standing surface 1a2 of the tapered surface 1a.
Is set to be equal to or smaller than an angle α formed between the tapered surface 2a and the standing surface 2a2, and the distance L between the bottom surface 1a1 and the bottom surface 2a1 is set.
2 becomes extremely close, and the current flows predominantly, so the current density increases, and the upper portion 2a of the bottom surface 2a1 of the material 2 to be joined is increased.
7 becomes easy to melt.

6 to 8 show sectional shapes of joints between different kinds of materials in other embodiments. In the embodiment of FIG. 6, the taper angles of the taper surfaces 1a and 2a forming the male and female pairs of the two materials 1 and 2 to be bonded are different, and the lower end portion of the taper surface 1a of the material 1 to be bonded is the taper surface of the material 2 to be bonded. Pressure is applied in a state of being in point-contact with and abutting on the central portion of 2a, and current is applied to heat and activate the interface to perform bonding.

In the embodiment of FIG. 7, the taper surface 1a of the material 1 to be joined is formed in two steps, the bottom surface 1a1 and the standing surface 1a2,
The contact portion 1a7 of this corner is pressed in a state of being in point contact with and abutted against the tapered surface 2a of the material 2 to be welded, and is energized to heat and activate the interface to perform welding.

In the embodiment of FIG. 8, the taper surface 1a of the material 1 to be joined is formed in two steps, that is, the bottom surface 1a1 and the standing surface 1a2.
The bent contact portion 1a8 is connected to the taper surface 2 of the joined material 2.
The contact portion 2a3 of a is pressed in a state of being in point-contact with and brought into contact with the contact portion 2a3, and the interface is heated and activated by energization to perform joining.

In this resistance joining method between different kinds of materials, the surface roughness of the tapered surface of the materials to be joined is adjusted to Ra 0.1 to 10,
Even if the surface cleanliness is poor, it does not affect the bonding strength.In addition, the as-cast surface condition is used for the taper surface of the material to be bonded. Similarly, if the surface cleanness is poor, it also affects the bonding strength. Since there is no cutting coolant or lubricating oil attached, there is no need for cleaning and it is an excellent joining method for in-line joining.

Next, a press machine used for carrying out the resistance joining method between different kinds of materials will be described. 9 is a front view of the press machine, FIG. 10 is a side view of the press machine, and FIG. 11 is a graph showing a pressing pattern, a current value pattern, and a sink amount.

In this press device 24, a lower platen 26 is fixed to a lower portion of a base 25, and an upper platen 27 is arranged above the lower platen 26 so as to come in contact with and separate from the lower platen 26. I have set up. The upper platen 27 is fixed to the lower end of a rod 28a, which serves as the working end of a cylinder device 28 mounted on the upper part of the base so that the axis of the upper platen 27 is oriented vertically.

The lower platen 26 and the upper platen 27 have a structure in which power is supplied from a power supply device (not shown) through the conductive members 26a and 27a, respectively. The conductive member 27a connected to the upper platen 27 is configured to be deformed or moved up and down according to the lifting operation of the upper platen 27. Further, in this embodiment, the upper platen 27 serves as an anode and the lower platen 26 serves as a cathode.

On the upper part of the base for supporting the cylinder device 28, the reflecting member 2 fixed to the front part of the upper platen 27 is provided.
9 is equipped with a laser displacement meter 30 for reflecting the laser beam and measuring the displacement amount of the upper platen 27 from the distance from the reflecting member 29. To join, first, the lower electrode 31 is fixed on the lower platen 26, the cylinder head body of the material 2 to be welded is placed and fixed on the lower electrode 31, and the valve seat of the material 1 to be welded is placed. Then, the upper electrode 33 is placed.

Next, the cylinder device 28 is driven to lower the upper platen 27, and the valve seat of the material 1 to be bonded is pressed against the cylinder head body of the material 2 to be bonded with a constant pressing force via the upper electrode 33.

This pressing force is changed based on the pressing force pattern shown by the solid line in FIG.

That is, that is, a relatively low constant first
The pressing force P1 is applied at the beginning of the joining process, and thereafter, a relatively high constant second pressing force P2 is applied until the end of the descent.

After starting the pressurization by the first pressing force P1,
When the upper platen 27 stabilizes, the laser displacement meter 3
The distance between this and the reflection member 29 is measured by 0, and this distance is recorded as the lowering start position of the upper platen 27. In addition, after the time T1 has elapsed from the start of the pressurization by the first pressing force P1 as shown in FIG. 11, a voltage is applied to the upper platen 27 and the lower platen 26 so that a voltage is applied between these platens, that is, the upper electrode 33, Valve seat of bonding material 1,
A current is passed through the cylinder head body of the material to be bonded 2 and the lower electrode 31. At this time, a current flows from the upper electrode 33 toward the cylinder head body of the material 2 to be joined. The current value at this time is also changed based on the current value pattern shown by the line in FIG. That is, after the current value has increased, the current value is once reduced to near 0, and then the current value is further increased to 0 while the pressing force is being applied at the end of the joining.

At this time, since the area of the portion where the materials to be joined 1 and 2 come into contact with each other is extremely small, the electrical resistance increases when electricity is applied, and the contact portion generates heat. This heat is conducted to the entire contact interface between the materials to be joined 1 and 2. When the temperature of the contact interface between the materials to be joined 1 and 2 rises in this manner, the atoms of the material metals that are pressed into contact with each other in the solid state will actively move, and these atoms will diffuse to each other. Become.

When the temperature near the interface further rises and a part of the eutectic alloy layer changes to the liquid phase, the atom diffusion phenomenon becomes more active, and this eutectic alloy layer grows and accompanies it. The interface between the solid phase and the liquid phase expands.

A part of this eutectic alloy layer is removed from the contact portion, and the material 1 to be bonded begins to sink into the material 2 to be bonded at time T2 in FIG. In this way, the pressing force is increased to the second pressing force P2 when the time T3 shown in FIG. 11 is reached after the material to be welded 1 starts to sink.

As the pressing force increases, the amount of plastic flow of the alloy increases, and accordingly, the amount of eutectic alloy to be excluded increases. As a result, a new eutectic alloy is newly formed in the unreacted portion of the contact portion, and the above phenomenon is repeated, and the eutectic alloy layer is made into a liquid phase and is further eliminated.

When the time T4 shown in FIG. 11 is reached after the pressing by the second pressing force P2 is started, the current value is once set to 0.
Decrease to near and then increase to the original value. By lowering the current value, heat generation is temporarily suppressed, plastic flow is suppressed, and as shown in FIG. 11, the rate of increase in the submerged amount of the material to be welded 1 is temporarily reduced. The reason for temporarily lowering the current value in this way is to prevent the alloy from being melted by heat.

After the current value is raised to the original value as described above, it is gradually decreased to 0 between the time T5 and the time T6. Not only while the current is flowing, but also after the power supply is cut off, the reaction proceeds until the temperature drops to the temperature at which the reaction cannot be performed, and the formation of the eutectic alloy layer → liquid layering → elimination associated with plastic flow , And the phenomenon of atomic interdiffusion between the iron-based sintered alloy and the aluminum alloy occur simultaneously, the material 1 to be bonded continues to sink and becomes embedded in the material 2 to be bonded.

When the amount of subsidence does not substantially increase as shown in FIG. 11 (at time T7), the pressing by the cylinder device 28 is stopped and the distance between the laser displacement meter 30 and the reflecting member 29 is stopped. To upper platen 27
After obtaining the final position of, raise the upper platen 27,
The material to be joined 2 is removed from the press device 24. It should be noted that the average current value and the total energization time are also obtained by the time all steps are completed.

FIG. 12 shows a variation and an application example of a joining form to which the resistance joining method between different kinds of materials is applied. As a basic combination of shapes, a block 90 having a hole as shown in FIG. , An example of joining the ring 91,
An example of joining the cylinder 92, the ring 93, and the shaft 94 in FIG. 12B, an example of joining the cylinder 95 and the plate 96 in FIG. 12C, a block 97, the plate 9 in FIG.
There are 8,99 joint examples.

As target parts, a valve seat, a bolt seat surface, a spark plug seat surface as an application example of FIG. 12 (a), a cam shaft, a connecting rod, a valve guide, and FIG. 12 as an application example of FIG. 12 (b). The application example of (c) includes a lifter valve and a piston, and the application example of FIG. 12 (d) includes a piston, a rocker arm, a clutch hub, a clutch plate, and the like.

Further, the different kinds of materials to be joined are not particularly limited as long as they are conductive metals, and for example, AC4B material, AC2 material.
B material or the like can be adopted. Further, as the material of the insert material, for example, copper, tin, zinc, silver, brass, silicon, aluminum silicon alloy or the like can be used,
Any material may be used as long as it forms a eutectic alloy with the material metal of the material to be joined.

[0050]

As described above, according to the first aspect of the present invention, the taper surfaces forming a pair of male and female are formed on different kinds of materials to be joined having conductivity, and the taper surfaces are brought into contact with each other. Since the interface is heated and activated by pressurizing and energizing to join, the material to be joined heats up and is joined at the contact portion because the electrical resistance of the contact portion is larger than that inside, and the material to be joined is the base metal Bonding strength equivalent to strength is obtained, it can be processed in the atmosphere, the time required for bonding is shortened, and productivity is extremely good.

According to the second aspect of the present invention, since the tapered surfaces forming a male and female pair are formed in two steps, the joining strength of the materials to be joined is increased.

According to the third aspect of the present invention, since at least one tapered surface forming a male-female pair has a contact portion that makes a line contact when viewed from the circumference, the current density of the contact portion that makes a line contact increases, From this portion, it is easy to melt, the time required for joining is shortened, and productivity is extremely good.

According to the fourth aspect of the present invention, since at least one tapered surface forming a male-female pair has a contact portion that makes surface contact when viewed from the circumference, the current density of the contact portion that makes surface contact increases, From this portion, it is easy to melt, the time required for joining is shortened, and productivity is extremely good.

According to the fifth aspect of the present invention, since the taper surfaces forming the male and female pairs are set to different taper angles, the current density at the line contacting portion increases, and melting easily occurs from this portion, which is required for joining. The time is short and the productivity is extremely good.

According to the sixth aspect of the present invention, a thin insert material is adhered to at least one tapered surface forming a male-female pair by plating or the like to perform joining by pressurization, and after the joining is completed, the insert material remains at the joining interface. Since it does not, an alloy layer is formed near the interface, and the bonding strength increases.

According to the invention described in claim 7, since the surface roughness of the tapered surface is adjusted to Ra 0.1 to 10, even if the cleanliness of the surface is poor, the bonding strength is not affected. There is no need for cleaning even if lubricating oil adheres, and it is an excellent joining method for in-line joining.

According to the eighth aspect of the present invention, since the as-cast surface state is used for the tapered surface, similarly, even if the surface cleanliness is poor, the joining strength is not affected. Therefore, cutting coolant or lubricating oil is not used. It is excellent as an in-line joining method because it does not require cleaning even if it is attached.

[Brief description of the drawings]

FIG. 1 shows a cross-sectional shape of a joint portion between dissimilar materials and a joining process.

FIG. 2 shows a cross-sectional shape and a joining process of a joining portion between different kinds of materials according to another embodiment.

FIG. 3 shows a cross-sectional shape of a joint between different kinds of materials according to another embodiment.

FIG. 4 shows a sectional shape of a joint portion between different kinds of materials according to still another embodiment.

FIG. 5 shows a cross-sectional shape of a joint between different kinds of materials according to still another embodiment.

FIG. 6 shows a cross-sectional shape of a joint portion between different kinds of materials according to another embodiment.

FIG. 7 shows a cross-sectional shape of a joint between different kinds of materials according to another embodiment.

FIG. 8 shows a cross-sectional shape of a joint between different kinds of materials according to another embodiment.

FIG. 9 is a front view of the press device.

FIG. 10 is a side view of the press device.

FIG. 11 is a graph showing a pressing force pattern, a current value pattern, and a sink amount.

FIG. 12 is a diagram showing a variation and an application example of a joining mode to which a resistance joining method between different kinds of materials is applied.

[Explanation of symbols]

 1, 2 Materials to be welded 1a, 2a Tapered surface

Claims (8)

[Claims] 1. A taper surface forming a male-female pair is formed on different kinds of materials to be joined having conductivity, and the taper surfaces are pressed against each other in a state of being in contact with each other to heat and activate the interface. A resistance joining method between dissimilar materials characterized by joining. 2. The resistance joining method between different kinds of materials according to claim 1, wherein the tapered surfaces forming the male and female pairs are formed in two steps. 3. The resistance joining method for dissimilar materials according to claim 1 or 2, wherein at least one tapered surface forming the male-female pair has a contact portion that makes line contact when viewed from the circumference. . 4. The resistance joining method for dissimilar materials according to claim 1 or 2, wherein at least one tapered surface forming the male-female pair has a contact portion that makes surface contact when viewed from the circumference. . 5. The resistance joining method between dissimilar materials according to claim 1, wherein the tapered surfaces forming the male and female pairs have different taper angles. 6. A thin insert material is adhered to at least one tapered surface forming the male-female pair by plating or the like, and joining is performed by pressurizing electricity, and after the joining is completed, the insert material does not remain at the joining interface. The resistance joining method between different kinds of materials according to any one of claims 1 to 5. 7. The surface roughness of the tapered surface is Ra 0.1-1.
The resistance joining method between different kinds of materials according to any one of claims 1 to 6, wherein the resistance joining method is adjusted to 0. 8. The resistance joining method between different kinds of materials according to claim 1, wherein the as-cast surface state is used for the tapered surface.