JP2000263250A - Joining method for different kind of metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more inexpensive joining method by which the direct joining of a mating material to a piping structure is possible, joining reliability such as strength, a tightness, etc., is high, the treatment of the end face of a joining tube is easy and tolerances in dimension are large in the joining of different kinds of metals such as copper, aluminum, etc. SOLUTION: In the combination of the different kinds of metals showing an eutectic solidification phenomenon at the time of alloying, joining is performed by a process making a copper tube 1 and an aluminum tube 2 adhere closely by rubbing the abutted surface of the two materials by rotating the copper tube 1 after shifting it in the peripheral direction while it is pressed and is brought into contact, a process making eutectic melting liquid generate by heating the aluminum tube 2 up to the vicinity of a low melting point held by the aluminum tube 2 under pressure welding and a process making the eutectic melting liquid solidify by cooling. The joining with high reliability can be provided because an oxidized film on the surface of a metal, which is the obstacle of the joining by friction caused by rotating and sliding, can be easily ejected and making the active surfaces of the metals adhere closely is possible. Even such a time when some deformations are generated in a pre-stage by using a soft metal, the shape of the end face of a joining part can be learned by a mating material by revolving, and a high productivity can be realized such as the extent of the allowable ranges of joining dimensions, the improvement of a yield, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combination of metals exhibiting a eutectic solidification phenomenon during alloying, for example, the joining of copper and aluminum, and more particularly, to the joining of metal piping circuits such as refrigeration circuits and hot water piping. TECHNICAL FIELD The present invention relates to a method for manufacturing a joined pipe when a different metal piping structure is introduced into a pipe, and a method for bonding different metals to the end face of the piping structure.

[0002]

2. Description of the Related Art In general, a copper pipe having good workability and easy to join by brazing or the like is often used for a refrigeration circuit or a hot water pipe. Among such piping circuits, for example, in a refrigeration circuit, a plate-type heat exchanger or the like is manufactured by inserting a hairpin-type copper pipe into a perforated and laminated aluminum fin, and dissimilar metals. Used in complex combinations.

On the other hand, in recent years, materials used for electric appliances and the like are required to be easily recyclable. In particular, in order to improve the ease of separation during disassembly, the heat exchanger and the like are made of the same material. Products are required. When manufacturing piping structures such as heat exchangers with the same material, it is preferable to use aluminum that is lightweight and can be recycled with low energy at the time of recycling, and can be separated from other metals by simply separating it from the piping circuit at the time of disposal This makes recycling easier.

[0004] In order to use a piping structure made of an easily recyclable material such as aluminum in a piping circuit mainly composed of copper pipes, a joint between copper and aluminum is required. When joining aluminum and copper, it is difficult to heat uniformly because both have high thermal conductivity, and the melting point of aluminum is about 660 ° C, which is far from the melting point of copper of about 1080 ° C. There is a dense and chemically stable oxide film on the aluminum surface and no metal active surface has appeared. Aluminum and copper alloys have very hard and brittle intermetallic compounds. When there is a large thickness at the bonding interface, the bonding strength is significantly reduced, for example, because the bonding involves many difficulties, and only a very special bonding method has been put to practical use.

[0005] Specifically, flash butt welding, eutectic welding, friction welding and the like are used. In particular, since these joining methods require a high-voltage power supply and a large rotating power, a joining pipe is manufactured as a separate part, and later, the same kind of metal is joined by welding or brazing. In addition, in addition to the above-mentioned butt-joining method, the above-mentioned joining method of overlapping has been widely used, particularly for the purpose of ensuring fluid tightness such as a refrigerant pipe.

[0006] In the flash butt welding, electrodes are attached to a copper tube and an aluminum tube, respectively, and the joint portion of both the copper and the aluminum is melted and softened by flashing. Finally, a contact pressure of about 1 kg is applied. To join. In order to adhere in a melt-softened state, the oxide film on the aluminum surface remaining as a thin-film solid on the very surface is mechanically removed, and both molten metals are alloyed and joined.

[0007] Eutectic welding is a joining method utilizing the properties of copper and aluminum when they are alloyed. The eutectic temperature of the Θ phase and the aluminum α solid solution is about 550 ° C., and the eutectic alloy liquid phase can be created from the aluminum solid phase. In other words, it is possible to form a eutectic melt from solid-phase diffusion by bringing the metals into contact at around 550-660 ° C where neither the copper tube nor the aluminum is melted. Becomes

The actual procedure is described in, for example,
The means presented in Japanese Patent No. 5467 is to form a eutectic layer while heating a copper tube having a tapered end face, externally fitting the aluminum tube, and expanding the diameter of the aluminum tube.
A method has been proposed in which the oxide phase on the aluminum surface is eliminated, and the aluminum and copper are brought into close contact with each other and joined.
Joining is possible with a relatively simple device, the joining surface can be widened, and the eutectic layer is formed extremely thin, so that there is an advantage that a joining tube having high sealing performance and high joining strength can be manufactured at low cost.

In the friction welding, one of the copper pipe and the aluminum pipe is rotated in a state where the copper pipe and the aluminum pipe are brought into contact and pressurized, and the oxide film on the aluminum surface is mechanically removed by the friction of the contact surface, and further joined by frictional heat. The joining is completed by rapidly stopping the rotation while the part is melt-softened. The eutectic melt is generated from the melting and softening or solid phase diffusion of copper and aluminum by frictional heat, and both metals are alloyed and joined, and it is possible to reliably remove the oxide film that serves as a joining barrier. Joining is possible.

As a specific procedure, butt friction welding with a core metal having good releasability inserted (Japanese Patent Laid-Open No. 52-48)
No. 542), friction welding while inserting an aluminum pipe into a copper pipe aluminum pipe whose end face is tapered, and expanding and ironing the aluminum pipe (Japanese Patent Laid-Open No. 54-1979).
No. 131550) has been proposed.

[0011]

The joints of copper and aluminum pipes used for refrigerant pipes and the like are required to have a high sealing property for the fluid flowing in the pipes, and the strength of the joints is very important for pipes subject to internal pressure. Becomes In particular, the piping that makes up the refrigeration circuit in the refrigerator is considered to have the problem of depletion of the ozone layer and its impact on global warming. In addition to dechlorination of Freon, which is a refrigerant, flammable hydrocarbon-based refrigerants are used overseas. For example, there is an increasing demand for suppression of refrigerant leakage.

Further, for the same reason as described above, it is required to reduce the number of joints. Therefore, instead of manufacturing a joint part of a copper tube and an aluminum tube separately and joining the same kind of metal later as in the related art, There is a need for a method capable of directly joining a dissimilar metal tip tube to the piping structure itself.

Here, especially a general-purpose aluminum pipe has a low elasticity limit even if it is a hard material, and the roundness of the pipe is often lost during the manufacturing process. Therefore, in order to prevent a joining defect, for example, when joining a copper chip tube or the like to an aluminum piping structure, a joining method capable of allowing a certain degree of deformation is required.

In spite of the specifications and characteristics required for the joint based on the above applications, flash butt welding and friction welding can secure high reliability such as sealing performance and joint strength, but require high voltage power supply and large rotating power. Extensive joining equipment was required, and it was not suitable for direct joining to a piping structure. Further, in flash butt welding, both metals must be brought close to the vicinity of contact and flashed, and in friction welding, the dimensional accuracy of the pipe joint end face must be maintained at a high level in order to make the two rotate and relatively move relatively. Therefore, the deformation of the aluminum tube in the previous process cannot be tolerated, and a large amount of cost is required in the production of the joined tube to secure a high degree of dimensional accuracy.

In flash butt welding, eutectic welding, and friction welding of superposition, although there is a certain degree of dimensional tolerance, in order to eliminate the oxide film on the aluminum surface and bring both metals into close contact with each other, Pre-processing such as tapering the end face of the copper pipe is required for the purpose of expanding and ironing the aluminum pipe by press-fitting the copper pipe. Furthermore, the end face of the tapered portion may protrude significantly toward the inner diameter side after joining, and the protruding portion acts as a resistance of the fluid flowing in the pipe, so post-processing such as drilling is required to eliminate this. There is. Post-processing is not possible in order to realize direct bonding, and pre-processing such as taper also increases the cost of bonding.

In order to perform direct joining, large-scale joining equipment is not required, the dimensional tolerance of each pipe end face to be joined is large, and the simpler end face treatment is combined with reliability such as sealing performance and joint strength. Therefore, a bonding method having a high degree of hardness has been required.
Even in the case of manufacturing a simple joint pipe, it is a simple facility that can improve the product yield, etc., the end face of the joint is easy to process, and even if the tolerance of the end face dimension is large, the reliability that can be joined is large. There was a need to realize a high method.

The present invention has been made in order to solve the above problems, and does not require large-scale equipment that requires a complicated driving unit having a large electric capacity and a large pressing force related to bonding.
An object of the present invention is to provide a method in which the dimensional tolerance of each member to be joined is large, the end face processing is easy, and post-processing is not required, and a joint with high reliability such as strength can be realized at low cost.

[0018]

According to a first aspect of the present invention, there is provided a method for joining dissimilar metals according to the present invention, wherein at the time of joining dissimilar metals exhibiting a eutectic solidification phenomenon during alloying, at least one of them is rotated while being circumferentially shifted. Rubbing the contact surfaces to form a close contact portion, and preheating or post-heating so as to be near a low melting point temperature of any metal so as to generate a eutectic melt in the close contact portion. By having a step and a step of solidifying the eutectic melt by cooling,
The oxide film on the metal surface serving as a junction barrier can be broken and easily removed. In addition, the shape of the joining surface can be learned by the counterpart material by the rotation.

In the second invention, when connecting different metal tubes or a tube and a rod, which exhibit a eutectic solidification phenomenon during alloying, at least one of the tubes is pressurized and moved in the circumferential direction while relatively moving in the axial direction. Forming a close contact portion by rubbing the peripheral surfaces by rotating in a staggered manner, and preheating or heating to a temperature close to a low melting point temperature of any metal so as to generate a eutectic melt in the close contact portion. By providing a step of post-heating and a step of solidifying the eutectic melt by cooling, the oxide film on the metal surface serving as a bonding barrier can be broken and easily removed. In addition, the shape of the joining surface can be learned by the counterpart material by the rotation.

Further, the third invention is characterized in that, when connecting pipes of different metals showing a eutectic solidification phenomenon at the time of alloying, or connecting pipes and rods, at least one of them is pressurized and relatively moved in the axial direction to make contact. A step of forming a close contact portion by rubbing the circumferential surfaces by rotating in a circumferential direction from the contacted state, and in the vicinity of a low melting point temperature provided by any metal so as to generate a eutectic melt in the close contact portion By providing the step of preheating or postheating and the step of solidifying the eutectic melt by cooling as described above, the oxide film on the metal surface serving as a bonding barrier can be broken and easily removed. In addition, the shape of the joining surface can be learned by the counterpart material by the rotation.

Further, the fourth invention can overcome many bonding barriers such as the presence of a stable oxide film on the aluminum surface even when the dissimilar metal is a combination of copper and aluminum.

A fifth aspect of the present invention is to use an outer fitting tube made of a dissimilar metal having a flared end portion, and using an end portion on the insertion side which is chamfered or cut. In addition, it is not necessary to form each joint end in an irregular shape.

According to a sixth aspect of the present invention, an aluminum tube is used for the outer fitting side of the dissimilar metal and a copper tube is used for the inserting side, so that abnormal deformation can be prevented.

According to a seventh aspect of the present invention, the rotation of the dissimilar metal in the circumferential direction is performed at 360 ° or less with respect to the movement distance of 10 mm in the axial direction, which causes abnormal deformation such as twisting. Absent.

An eighth aspect of the present invention is to dispose a metal core inside the aluminum tube by using a copper tube on the outer fitting side of the dissimilar metal and an aluminum tube on the insertion side. Can prevent deformation

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a side sectional view showing the first embodiment, and FIG.
In the first embodiment, a copper tube 1 is inserted and joined inside an aluminum tube 2. The copper pipe 1 is subjected to chamfering processing as necessary when burrs or the like are present at the pipe end or for cleaning, but is not particularly subjected to end face processing. The aluminum tube 2 coaxially facing the copper tube 1 has a simple end-diameter expanding process such as flaring at the tube end. The difference between the outer diameter of the copper tube 1 and the inner diameter of the aluminum tube 2 (difference / 2 = insertion allowance)> 0, and the maximum inner diameter of the aluminum tube 2 flared ≧ the copper tube 1 It has the relationship of the end outer diameter. The outer diameter of the end of the copper tube 1 is equal to or less than the maximum inner diameter of the aluminum tube 2 which has been subjected to flaring, and the difference is a maximum insertion allowance × 2.
The inner diameter of the aluminum pipe 2 should be 1.3 times or less.

The copper tube 1 and the aluminum tube 2 are coaxially opposed to each other, and a high-frequency coil 3 for high-frequency induction heating of the copper tube 1 is provided.
To about 570 ° C to 900 ° C. At this time,
The melting point of the aluminum tube 2 is about 660 ° C., but the melting point of the copper tube (1085 ° C.) in consideration of cooling of the copper tube 1 during the joining process.
Overheating of about 250 ° C. can be provided in the following range. The copper tube 1 after heating to the desired temperature is rotated and inserted while being rubbed in the circumferential direction, and then cooled by an inert gas such as nitrogen to solidify the eutectic melt to achieve joining. is there. When heating the copper tube 1, the aluminum tube 2 can be preheated by bringing the aluminum tube 2 close to or in butt contact with the copper tube.

The amount of rotation at the time of insertion is preferably 360 ° or less, particularly preferably 30 ° to 180 °.

When a rotation of 360 ° or more per 10 mm is given, excessive shear stress is applied to the abutting pipes to secure a circular shape, resulting in wear and deformation. Problems such as remarkable torsion deformation of the tube occur. As a result, the strength of the aluminum pipe in the vicinity of the joint decreases, and the reliability of the joint such as a pipe under internal pressure decreases.

Further, the heat generated by friction increases at the rubbed portion between the copper tube 1 and the aluminum tube 2 and the eutectic layer grows abnormally thick, so that the toughness of the joint decreases.

Therefore, the conditions for inserting the tube are such that the oxide film can be efficiently removed without deforming the joint.
The rotation range is limited to 360 ° or less for a 10 mm insertion amount of the tube. The axial feed speed (insertion speed) of the copper tube 1 is 1
２０20 mm / sec.

FIG. 3 is a schematic view showing the joining apparatus used in the first embodiment. Copper tube 1 and aluminum tube 2
Are held coaxially by the clamp 4. Thereafter, power is supplied to the high-frequency coil 3 for high-frequency induction heating of the copper tube 1. The copper tube 1 heated to a desired temperature is advanced by the cylinder 6 toward the aluminum tube 2 while being turned by the rotation amount adjusting jig 5, and inserted while the outer surface of the copper tube 1 rubs against the inner surface of the aluminum tube 2. At the same time as the copper tube 1 is inserted into the aluminum tube 2 to a predetermined position, nitrogen (or other non-oxidizing gas) is sprayed to cool the joined body and solidify the eutectic liquid.

In the first embodiment, the copper tube 1 is heated by the high-frequency coil 3 and then joined by rubbing and inserting. However, the heating may be performed after the insertion. Is 550-660 ° C. The aluminum pipe 2 does not need to be subjected to flare processing at the pipe end. In addition, copper tube 1
Move and rotate, but the aluminum tube 2 may be moved and / or rotated. Although the case where the tubular body is inserted has been described, the present invention is also applicable to the case where a rod-shaped body or the like is joined. The high frequency induction heating may be replaced by another heating means such as burner heating.

Embodiment 2 In the first embodiment, the copper tube is inserted into the aluminum tube. In the second embodiment, the aluminum tube is inserted into the copper tube so as to be joined. As shown in FIG. 4, the copper tube 1 has been subjected to a simple end face diameter increasing process such as flaring at the tube end. The aluminum tube 2, which is coaxially opposed to the copper tube 1, is subjected to chamfering as necessary if there is a burr or the like at the end of the tube or to clean it. It has not been applied. The joining conditions are the same as in the first embodiment, and the range of the insertion allowance (substantially equal to the diameter reduction of the aluminum tube 2) is also the same.

In addition, when inserting a soft thin-walled pipe such as aluminum, the core metal 7 is liable to be deformed such as a zigzag due to a pressing force at the time of insertion and a torsion at the time of rotation. To prevent this, a material having good releasability is inserted as necessary. The material is stainless steel, and a silicon-based or carbon-based material is used as a release agent within a range that does not flow into the joint. The clamp 4 may be used as necessary to restrain the joint of the aluminum tube 2 and its periphery from outside so as to suppress deformation of the zigzag and the like. FIG. 5 is a schematic view showing an aluminum heat exchanger which is a piping structure made of all aluminum having a joint portion by inserting an aluminum tube into a copper tube.

[0036]

EXAMPLES Table 1 shows examples based on the above-described embodiment.
In addition, a comparative example based on a different joining method is shown, and the results of a tensile test and the results of confirming the sealing performance by a water leakage test are also shown. In Examples 1 and 2, test materials were prepared using the bonding apparatus shown in FIG.

Embodiment 1 The aluminum pipe material to be joined is JIS-A1050-H112, and the copper pipe is JIS-A
C1220-1 / 2H. The copper tube shown in FIG. 1 is inserted into an aluminum tube.
After that, at an insertion speed of 10 mm / sec, about 90 ° / 1
A rotation of 0 mm was given, and press-fitting was completed at an overlap margin of about 10 mm. At the same time, nitrogen was blown to cool the joined body and solidify the eutectic melt.

FIG. 7 is a photomicrograph of a cross section of the bonded portion after bonding.
Shown in The eutectic layer was about 30 μm, and no fragile intermetallic compound single layer region was observed. Only a single eutectic layer was observed as a thin layer, confirming that a sound bonded body was obtained.

Embodiment 2 FIG. The same material as in Example 1 was heated and rotated and inserted by a method of externally fitting the copper tube side. At this time, the aluminum pipe side was not a simple short pipe, but an aluminum heat exchanger as a piping structure made of all aluminum shown in FIG. At this time, since the soft aluminum heat exchanger 8 and the aluminum header 9 side have an inner diameter, a stainless steel core was used to secure the inner diameter.
In the tensile test after joining, only the joining portion was cut off.

Comparative Example 1 Using a copper tube and an aluminum tube having the same diameter as in the above embodiment, both butted end faces were chamfered and then joined by flash butt welding. At this time, the current density of the flash current was about 50 A / mm ² , and the pressing force was about 1 kg / mm ² . After joining, the protruding portion on the inner diameter side was removed by drilling.

Comparative Example 2 As shown in FIG. 6, the copper tube 1 side was tapered, heated and pressed into an aluminum tube 2 having an inner diameter slightly smaller than the outer diameter of the copper tube 1, and joined by a eutectic melt. At this time, high-frequency induction heating was used to heat the copper tube 1, and when the temperature reached about 700 ° C., the insertion speed was about 10 mm / s.
The injection was performed at ec, and the insertion was completed at an overlap of about 10 mm, followed by cooling with nitrogen gas.

[0042]

[Table 1]

In the joining by the flash butt welding of the butt shown in Comparative Example 1, peeling occurred in three out of 100 joints in a tensile test, and a leak defect was confirmed in 15 out of 100 joints in a water leak test. Was done. With this method, the stability of the joining operation such as flash current and upset force at the time of joining is ensured, and although relatively reliable joining is possible, the joining area is small and continuous small defects that lead to leakage failure are completely eliminated. Cannot be excluded.

In the joining by lap press-fitting shown in Comparative Example 2, the sealing reliability is very high because even if a joining area is large and a small defect or the like is generated, it is unlikely that a leakage failure occurs. However, as in Comparative Example 2, when the insertion margin is small and the expansion and ironing of the aluminum pipe is not large, the oxide film on the aluminum surface is not sufficiently removed, and the joint strength may not be sufficiently exhibited.

On the other hand, in the embodiment, in the case of the embodiment 1 in which the copper tube is rotatably inserted into the aluminum tube, and in the case of the embodiment 2 in which the copper tube is rotatably externally inserted, the joining is performed with sufficiently high reliability. In the tensile test, only the aluminum tube portion was broken, and there was no peeling at the joint. Also, in the underwater leak test, no leak failure was observed because a sufficient bonding area was secured.

According to the present invention, joining of copper and aluminum, which are dissimilar metals, can be realized easily and with high reliability. In particular, as shown in Example 2, it became possible to easily incorporate a piping structure such as an all-aluminum heat exchanger having high recyclability.

The present invention is not limited to the method of joining a copper tube and an aluminum tube described in the above-described embodiment of the invention and shown in the drawings. Various modifications can be made without departing from the scope of the invention.

[0048]

According to the method for joining dissimilar metals according to the first invention of the present invention, when connecting dissimilar metals exhibiting the eutectic solidification phenomenon during alloying, at least one of the dissimilar metals is shifted in the circumferential direction and rotated. Rubbing the surfaces to form an intimate contact, heating or post-heating in advance near the low melting point of any metal so as to generate a eutectic melt in the intimate contact, and cooling. And a step of solidifying the eutectic melt, whereby the oxide film on the metal surface serving as a junction barrier can be broken and easily removed. In addition, even when slight deformation occurs in the previous process, the shape of the joint surface can be learned by the counterpart material by rotation, and the allowable range of the joint size can be increased, and high productivity such as improvement in yield can be realized.

In the method for joining dissimilar metals according to the second invention of the present invention, at the time of connecting tubes or rods of dissimilar metals exhibiting a eutectic solidification phenomenon during alloying, at least one of the tubes is pressurized to form a shaft. Forming a close contact portion by rubbing the circumferential surface by rotating in a circumferential direction while relatively moving in a direction, and a low melting point temperature provided by any metal so as to generate a eutectic melt in the close contact portion. By providing a step of pre-heating or post-heating to be in the vicinity and a step of solidifying the eutectic melt by cooling, the same excellent effects as described above can be obtained.

Further, in the method for joining dissimilar metals according to the third aspect of the present invention, at the time of connecting tubes or bars of dissimilar metals exhibiting a eutectic solidification phenomenon at the time of alloying, at least one of the tubes is pressurized to form a shaft. A step of forming a close contact portion by rubbing the peripheral surfaces by rotating in a circumferential direction from a state of being relatively moved and contacting in the direction, and forming any eutectic melt in the close contact portion by using any metal. By having a step of preheating or post-heating so as to be near the low melting point temperature, and a step of solidifying the eutectic melt by cooling,
The same excellent effects as above can be obtained.

In the method for joining dissimilar metals according to the fourth aspect of the present invention, even if the dissimilar metal is a combination of copper and aluminum, the dissimilar metal is inserted by being slid by rotation. Such as the presence of a stable oxide film
Many bonding barriers can be overcome, and bonding can be easily performed.

The method for joining dissimilar metals according to a fifth aspect of the present invention uses an outer fitting tube of a dissimilar metal obtained by performing flaring on an end portion thereof, and chamfering or cutting the end portion on the insertion side. Since it is not necessary to form the joining end portion of each metal into an irregular shape, the joining can be performed by an extremely simple end surface treatment such as flare.

Further, in the method for joining dissimilar metals according to the sixth invention, the outer fitting side of the dissimilar metal is an aluminum tube and the inserting side is a copper tube, and a hard metal material is tapered. The joint can be manufactured without reducing the inside diameter of the pipe without using a jig such as a metal core.

Further, in the method for joining dissimilar metals according to the seventh invention, the dissimilar metal is shifted in the circumferential direction and rotated at an angle of 360 ° or less with respect to a movement distance of 10 mm in the axial direction. The oxide film on the metal surface can be efficiently removed without deformation such as twisting.

Further, in the method for joining dissimilar metals according to an eighth aspect of the present invention, a core metal is disposed inside the aluminum tube, with the outer fitting side of the dissimilar metal being a copper tube and the inserting side being an aluminum tube. And it can be formed into an inner diameter with high dimensional accuracy.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing Embodiment 1 of the present invention.

FIG. 2 is a joining process diagram showing the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a joining device used in the first embodiment of the present invention.

FIG. 4 is a side sectional view showing Embodiment 2 of the present invention.

FIG. 5 is a schematic view showing an aluminum heat exchanger.

FIG. 6 is a sectional view showing the shape of a test tube of Example 2.

FIG. 7 is a microstructure photograph showing a cross section of a joint.

[Explanation of symbols]

1 copper tube, 2 aluminum tube, 3 high frequency coil,
4 clamp, 5 rotation amount adjustment jig, 6 cylinder,
7 core metal, 8 aluminum heat exchanger, 9 aluminum header.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B23K 103: 10 103: 16 103: 18 (72) Inventor Mitsada Hayakawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo (72) Shoichiro Morikawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4E067 AA05 AA07 BA05 BB02 DA13 DA17 DC06 EC06

Claims (8)

[Claims] 1. A step of forming a close contact portion by connecting at least one of the dissimilar metals exhibiting a eutectic solidification phenomenon during alloying by rotating at least one of them in a circumferential direction so that the contact surfaces are rubbed with each other. A dissimilar metal comprising: a step of preheating or postheating so as to be near a low melting point temperature of any one of the metals so as to generate a eutectic melt; and a step of solidifying the eutectic melt by cooling. Joining method. 2. When connecting different metal pipes or a pipe and a rod, which exhibit a eutectic solidification phenomenon during alloying, at least one of the pipes is pressurized and relatively displaced in the axial direction while being rotated in the circumferential direction. A step of forming a close contact portion by rubbing the peripheral surfaces, and a step of preheating or post-heating so as to be near a low melting point temperature of any of the metals so as to generate a eutectic melt in the close contact portion, Solidifying the eutectic melt by cooling. 3. When connecting tubes or rods of dissimilar metals exhibiting a eutectic solidification phenomenon during alloying, at least one of them is pressurized and relatively moved in the axial direction to move from a contact state to a circumferential direction. Forming a close contact portion by rubbing the peripheral surfaces by shifting and rotating, and preheating or post-heating so as to be near a low melting point temperature of any metal so as to generate a eutectic melt in the close contact portion. A method for joining dissimilar metals, comprising a step of heating and a step of solidifying the eutectic melt by cooling. 4. The dissimilar metal joining method according to claim 1, wherein the dissimilar metal is a combination of copper and aluminum. 5. The method according to claim 1, wherein the outer fitting tube made of dissimilar metal has a flared end, and the inner end has a chamfered or cut end. 4. The method for joining dissimilar metals according to any one of 2 and 3. 6. An aluminum tube on the outer fitting side of the dissimilar metal and a copper tube on the inserting side.
5. The method for joining dissimilar metals according to any one of 2, 3, and 4. 7. The method according to claim 1, wherein the rotation of the dissimilar metal in the circumferential direction is not more than 360 ° for a movement distance of 10 mm in the axial direction. Or a method for bonding dissimilar metals. 8. A metal core is disposed inside the aluminum tube, wherein the outer fitting side of the dissimilar metal is a copper tube and the inner side is an aluminum tube.
7. The method for joining dissimilar metals according to any one of 4, 5, and 6.