JP2001334371A - Eutectic bonding for copper-aluminum pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve defective bonding caused by the variance of a temperature condition in a heating process of a pipe and a cooling process after the completion of bonding in a method of eutectic bonding for a copper-aluminum pipe. SOLUTION: In a method of eutectic bonding performed by fitting an opening tip part 2a on the one end side of an aluminum pipe 2 to a convergently tapered part 1a formed on the one end side of a copper pipe 1, by melting a contact part by heating the fit portion of both pipes 1, 2 and by force-fitting the copper pipe 1 into the aluminum pipe 2, in a state that the fit portion of both pipes 1, 2 is restricted from the outside in the diameter direction with welding jigs 13a, 13b through an insulating body 15 and before the softening and the melting of the contact part while a push-in force F in the fitting direction is given to both pipes 1, 2 in advance, heat is generated on the fit portion by a high frequency induction coil 16 arranged through the above insulating body 15. Consequently, the above force-fitting is started with the softening and the melting of the contact part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for eutectic joining of copper and aluminum dissimilar metal pipes.

[0002] In this specification, the terms "copper" and "aluminum" are used to mean copper alloy and aluminum alloy, respectively.

[0003]

2. Description of the Related Art In a heat exchanger of a refrigerator or an air conditioner, a dissimilar metal joint pipe in which a copper pipe and an aluminum pipe are directly joined is used in some cases. It is manufactured by the eutectic bonding method shown in FIG.

In FIG. 1, a copper pipe (1) has an open end (2a) on one end side of an aluminum pipe (2) fitted to a tapered tapered portion (1a) formed on one end side thereof.
The fitting portions (1) and (2) are restrained from outside in the radial direction by restraining jigs (3a) and (3b). Then, after heating both pipes (1) and (2) for a certain period of time to melt the eutectic portion of the contact portion, the pushing force (F) in the fitting direction (tube axis direction) is applied to both pipes (1) and (2). , The copper pipe (1) is press-fitted into the aluminum pipe (2), and these pipes are eutectic bonded. At this time, the pipe
(1) (2) is heated by heating the restraining jigs (3a) and (3b) with the heater (5) to indirectly heat the pipes (1) and (2), or furthermore, copper pipe (1) Is directly heated by a burner.

[0005] While the indentation force (F) is applied, the surface oxide film is broken at the contact surface between the two pipes (1) and (2) to form a eutectic. The film and eutectic are discharged. At the interface between the two pipes (1) and (2), only a thin eutectic and a part of the finely crushed oxide film remain, and good bonding is achieved. Also, the end of joining is the press-fit amount (press-fit length)
When the fixed length is press-fitted, the pushing force (F)
End the grant. After joining, the joined pipe is cooled by air blow or the like so as not to grow the eutectic structure at the interface.

[0006]

However, since the timing of press-fitting of the pipe is controlled by the heating time of the pipe, the time required to reach the predetermined temperature varies, and the actual temperature at the start of press-fitting is not constant. And insufficient joining or poor melting occurred due to excessive melting.

[0007] Further, when continuously producing a joined pipe, the restraining jig always maintains a heated state. However, since the joining pipe is covered by the restraining jig even after joining, it takes time to cool. In addition to this, there is a problem that bonding failure due to overheating occurs.

Further, since there is a period in which heating and cooling are performed at the same time, the temperature of the restraining jig fluctuates due to the effect of cooling, and variations in temperature conditions also contribute to poor bonding.

SUMMARY OF THE INVENTION In view of the above technical background, an object of the present invention is to provide a eutectic joining method for a copper-aluminum pipe capable of eliminating a joining defect caused by a variation in temperature conditions in a pipe heating step or a cooling step after the end of joining. And

[0010]

In order to achieve the above object, a first eutectic joining method for a copper-aluminum pipe according to the present invention comprises a tapered taper formed at one end of a copper pipe (1). One end opening end (2a) of the aluminum pipe (2) is externally fitted to the part (1a), the fitting part of both pipes (1) and (2) is heated to melt the contact part, and the aluminum pipe (2 In the method of press-fitting the copper pipe (1) into the eutectic joint, the fitting portions of the two pipes (1) and (2) are restrained from outside in the radial direction by the restraining jigs (3a) and (3b). Before the softening and melting of the contact area, both pipes (1) (2)
The press-fitting is started with the softening and melting of the contact portion by heating the fitting portion in a state in which a pressing force (F) in the fitting direction is applied in advance.

A second method of eutectic joining of a copper-aluminum pipe is that a tapered tapered portion (1a) formed at one end of a copper pipe (1) is connected to an open end (1a) of an aluminum pipe (2). 2a) is externally fitted, the fitting part of both pipes (1) and (2) is heated to melt the contact part, and copper pipe (1) is pressed into aluminum pipe (2) to perform eutectic bonding In the fitting jig of the two pipes (1) (2) via a insulator (15)
(13a) (13b) is constrained from the outside in the radial direction, the high-frequency induction coil (16) disposed via the insulator (15) to heat the fitting site by melting the contact portion, characterized in that I do.

A third method of eutectic joining of a copper-aluminum pipe is that a tapered tapered portion (1a) formed at one end of a copper pipe (1) is connected to an open end (a) of one end of an aluminum pipe (2). 2a) is externally fitted, the fitting part of both pipes (1) and (2) is heated to melt the contact part, and copper pipe (1) is pressed into aluminum pipe (2) to perform eutectic bonding In the fitting jig of the two pipes (1) (2) via a insulator (15)
(13a) While being restrained from outside in the radial direction by (13b), the pressing force (F) in the fitting direction is previously applied to both pipes (1) and (2) before softening and melting of the contact portion, The press-fitting is started with the softening and melting of the contact portion by causing the fitting portion to generate heat by the high-frequency induction coil (16) arranged via the insulator (15).

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The eutectic bonding apparatus (A) shown in FIGS. 1 and 2 and the eutectic bonding apparatus (B) shown in FIGS.
It is a device for applying the eutectic bonding method of the present invention, and in any device, a tapered portion (1a) having a tapered shape at one end side
A pipe joined body in which a copper pipe (1) formed with an aluminum pipe (2) whose one open end (2a) is externally fitted to a tapered part (1a) of the copper pipe (1) is eutectic-joined. Is produced. The copper pipe (1) has a tubular extension (1b) integrally formed at the tip of the tapered portion (1a) with the same diameter as the outer diameter of the tip.

Further, in the present invention, the material composition of the copper pipe (1) is not limited, and a wide variety of oxygen-free, phosphorus-deoxidized copper, tough pitch copper and the like can be used. Also, the material composition of the aluminum pipe (2) is not limited, and high-purity aluminum, JIS 1000-based Al or Al
Alloy, 2000 series Al-Cu alloy, 3000 series A
1-Mn alloy, 4000 Al-Si alloy, 50
00-based Al-Mg-based alloy, 6000-based Al-Si-
Mg alloys, 7000 Al-Zn-Mg-Cu alloys and Al-Zn-Mg alloys can be widely used. (First Embodiment) The eutectic bonding apparatus (A) shown in FIG. 1 is composed of a pair of upper and lower split dies, and restraining jigs (3a) and (3b) for restraining both pipes (1) and (2), and cooling each pipe. Air blow as a means (BW
1) It has (BW2).

Each of the restraining jigs (3a) and (3b) has a groove (4a) (4a) (4a) (a) having a semicircular cross section from one side to the other side in the fitting direction of the pipes (1) and (2). 4b), the lower mold
Place both pipes (1) and (2) in the groove (4b) of (3b) and set the upper die (3a)
When both are fitted, both pipes (1) and (2) are inserted into the holes formed by the upper and lower grooves (4a) and (4b), and the pipe fitting portion is set so as to restrict the pipe fitting portion from the outside in the entire radial direction. ing. Furthermore, the restraining jigs (3a) and (3b) include a heater for heating.
(5) and (5) are provided, and the restraining jigs (3a) and (3b) are heated by the heaters (5) and (5), and both pipes (1) are heated by the restraining jigs (3a) and (3b). And (2) the fitting portion can be heated.

The material of the restraining jigs (3a) and (3b) is the one at the one end side of the aluminum pipe (2) which expands due to press fitting of the pipe fitting portion, particularly the tapered portion (1a) of the copper pipe (1). Any material may be selected as long as it can hold the outer shape.
Further, the restraining jigs (3a) and (3b) are not limited to the split type and may be a fixed type. Further, the heating means of the pipes (1) and (2) can be arbitrarily selected as long as the pipes can be heated,
In addition to the heater (5) described above, a burner or a combination of a heater and a burner can be exemplified.

The air blows (BW1) and (BW2) are both pipes.
(1) The pipes (1) and (2) are cooled at a predetermined timing when a eutectic is generated at the joint of (2).

Next, a method of eutectic bonding the two pipes (1) and (2) by the eutectic bonding apparatus (A) will be described.

The one end opening end (2a) of the aluminum pipe (2) is externally fitted to the tapered portion (1a) of the copper pipe (1) with a margin (L ₁ ), while the restraining jig (3a). (3b) groove (4a) (4
The pipes (1) and (2) are inserted into the b), and the fitting part of the length (L ₁ ) and the tapered part (1a) of the copper pipe (1) become the restraining jigs (3a) (3b)
The restraining jigs (3a) and (3b) are set so as to be located at the intermediate portions in the longitudinal direction of the grooves (4a) and (4b). Thereby, the fitting site of the two pipes (1) and (2) at the time of joining is restricted from the outside in the radial direction. In this restricted state of the pipe, a pushing force (F) is applied from the copper pipe (1) side in the fitting direction. The indentation force (F) needs to be sufficient to break the oxide film due to friction between the pipes and to discharge the broken oxide film and the generated eutectic, and is preferably 200 to 600 N.

Simultaneously with or after the pressing force (F) is applied, the heaters (5) and (5) are energized to apply the restraining jig (3a).
The two pipes (1) and (2) are heated via (3b). Heater (5) (5)
Is set to a temperature higher than the eutectic melting point (548 ° C.) of the Al—Cu alloy so that the actual temperatures of the two pipes (1) and (2) are heated slightly higher than the eutectic melting point. I do.

When the two pipes (1) and (2) are heated by the above-mentioned heating and the actual temperature approaches the eutectic melting point of 548 ° C., the two pipes (1) and (2)
(1) As soon as the contact portion of (2) softens and melts, as shown in FIG. 2, the copper pipe (1) is pressed into the aluminum pipe (2) by the pressing force (F) given in advance. Lively, joining is performed.

During this press-fitting and joining, first, FIG.
As shown in (a), at the contact portion between the two pipes (1) and (2), the oxide film (10) on the outer peripheral surface of the copper pipe (1) is broken, and atomic diffusion occurs. By further pushing, FIG. 5 (b)
As shown in (1), atom diffusion proceeds, eutectic (liquid phase) is generated, and the oxide film (10) floats in eutectic (liquid phase).
When the indentation is further continued, as shown in FIG. 5 (c), the eutectic / oxide film (10) is discharged, and the two pipes (1) and (2) come into contact with each other. The bonding state is such that only a part of the finely crushed oxide film remains.

The end of the joining is determined by the press-fit amount (length), and when the fixed length (L ₂ ) is press-fitted, the application of the pressing force is finished. After joining, the pipe is cooled by air blow (BW1) (BW2) so as not to grow the eutectic structure.

According to this method, the copper pipe is press-fitted when the contact portion starts to soften and melt regardless of the slow rate of temperature rise of the pipe, so that the molten state at the start of press-fitting is constant. For this reason, poor joining and variation in joining strength due to insufficient melting or excessive melting at the time of press-fitting are suppressed, and good joining is achieved.

When the eutectic crystal is formed while the copper pipe (1) is pressed into the aluminum pipe (2), the pipe (1) is prevented from being oxidized on the inner peripheral surface of the copper pipe (1). ) (2)
It is preferable to flow an inert gas such as nitrogen or argon therein.

During the eutectic bonding, eutectic alloy grains are formed on the outer peripheral surface of the tapered portion (1a) of the copper pipe (1). When this is extruded and moved along the outer peripheral surface of the tapered portion (1a) and is discharged from the tip into the aluminum pipe (2), the flow path in the pipe joint becomes an obstacle.
By increasing the protrusion length of the tapered portion (1a), it is conceivable to lengthen the creepage path for the eutectic alloy grains.In this case, however, the tip inner diameter of the tapered portion (1a) is reduced to a certain value. The inner diameter of the flow path cannot be secured.

On the other hand, in the present embodiment, a tubular extension (1b) having the same diameter as the outer diameter of the tip is integrally formed at the tip of the tapered portion (1a) of the copper pipe (1). Therefore, the eutectic alloy particles that have moved along the outer peripheral surface of the tapered portion (1a) can be retained on the outer peripheral surface of the extending portion (1b). Therefore, the eutectic alloy particles are prevented from being discharged into the aluminum pipe (2) as much as possible, and as a result, it is possible to prevent the formation of obstacles in the flow passage in the pipe joint. (Second Embodiment) The eutectic bonding apparatus (B) shown in FIGS. 3 and 4 is different from the eutectic bonding apparatus (A) in the first embodiment in that the pipes (1) and (2) are restrained and heated. -Different cooling methods.

In this pipe eutectic joining apparatus (B),
The restraining jigs (13a) and (13b) are formed of a pair of upper and lower split dies, each of which has a groove depressed in a semicircular cross section from one side surface to the other side in the fitting direction of the pipes (1) and (2). (14a) (14b)
have. When the two pipes (1) and (2) are arranged via an insulator (15) having a semicircular cross section along the grooves (14a) and (14b) and the upper and lower molds (13a) and (13b) are combined, The two pipes (1) and (2) are inserted into the holes formed by the grooves (14a) and (14b) of the insulator (1).
5) is set to be restrained through. Furthermore, the restraining jig (13b) has a built-in high frequency induction coil (16). When the upper and lower dies (13a) and (13b) are assembled, the coil (1
6) surrounds the pipes (1) and (2), and as shown in FIG. 4, an induced current (I) flows to heat the two pipes (1) and (2) themselves to heat the fitting portion. ing. In addition, the coil
(16) can be cooled by water cooling.

The material of the insulator (15) is a restraining jig.
(13a) It has strength to withstand the pushing force (F) for pipe press-fitting from outside in the radial direction by (13b), and can be selected arbitrarily as long as it has heat resistance and heat insulation to the heated pipe. Good, for example, ceramic can be recommended.

Next, a method of eutectically joining the two pipes (1) and (2) by the eutectic bonding apparatus (B) will be described.

The fitted copper pipe (1) and aluminum pipe (2) are set in the restraining jigs (13a) (13b) in which the insulator (15) is arranged in the grooves (14a) (14b). Then, the fitting portions of the two pipes (1) and (2) are restrained from outside in the radial direction via the insulator (15).

In this state, the coil (16) was energized to heat the fitting part, and the actual temperature of these parts reached near the eutectic melting point (548 ° C.) of the Al—Cu alloy, and the contact part began to melt. At this point, a pushing force (F) is applied from the copper pipe (1) side in the fitting direction. The copper pipe (1) is gradually pressed into the aluminum pipe (2) by the pressing force (F), and when the fixed length (L ₂ ) is pressed, the pressing force (F) application is finished. Cut off the current to the coil. During the injection, the surface oxide film is crushed, eutectic is formed, and the oxide film and the eutectic are discharged, so that eutectic bonding is performed. Since the coil (16) and the restraining jigs (13a) (13b) themselves are not heated,
As soon as the power supply to the coil (16) is cut off, the heating is cut off and the joint is cooled.

The timing of the indentation force (F) does not need to be exactly when the actual temperature of the pipe reaches the eutectic melting point of 548 ° C., but is preferably set in the range of 550 to 580 ° C.

According to this method, the pipes (1) and (2) are directly heated without heating the restraining jigs (13a) and (13b). Heating to 1) and (2) is interrupted, and after joining, it is quickly cooled to suppress eutectic growth and achieve good joining. In addition, since heating and cooling are performed without overlapping, the temperature condition is stable in any of the steps, and good bonding is achieved. (Third Embodiment) The same eutectic bonding apparatus (B) as in the second embodiment was used to change the timing of applying the indentation force (F) to perform bonding.

Both pipes (1) and (2) are restrained in restraining jigs (13a) and (13b) via an insulator (15), and a pushing force (F) is applied simultaneously with or after the application of the coil (16). Power on both pipes (1)
The fitting part of (2) is heated to generate heat. When the actual temperature of the two pipes (1) and (2) approaches the eutectic melting point of 548 ° C. due to this heating, the contact portions of the two pipes (1) and (2) begin to melt, and the indentation force (F ) By aluminum pipe
Copper pipe (1) is gradually pressed into (2), and eutectic bonding is performed. When the application of the pushing force (F) is completed at the time when the fixed length (L ₂ ) is pressed and the energization of the coil (16) is cut off, the heating is immediately cut off and the joint is cooled.

According to this method, the copper pipe is press-fitted when the contact portion starts to soften and melt regardless of the slow rate of temperature rise of the pipes (1) and (2). I do. For this reason, poor joining and uneven joining strength due to insufficient melting or excessive melting at the time of press-fitting are suppressed, and the pipes (1) and (2) are directly heated without heating the restraining jigs (13a) and (13b). As a result, the heating of the pipes (1) and (2) is immediately stopped by turning off the current to the coil (16), and after joining, the pipes are cooled quickly to suppress eutectic growth and achieve good joining. Is done. In addition, since heating and cooling are performed without overlapping, the temperature condition is stable in any of the steps, and good bonding is achieved.

[0038]

EXAMPLE A joining test of a copper pipe and an aluminum pipe was conducted based on the eutectic joining method of the present invention. In each of the following examples, the copper pipe (1) is made of C1220 (phosphorus deoxidized copper), and has an outer diameter of 8 mm, a thickness of 0.6 mm, a tapered portion (1a) having a length of 16 mm at one end, and a tip thereof. Length 5 to
As a round pipe and an aluminum pipe (2) having a cylindrical extension part (1b) of mm, a round pipe made of JIS A1050 and having an outer diameter of 8 mm and a thickness of 1.25 mm was used, and a copper pipe (1) was used.
Press-fitting amount into the aluminum pipe (2) of the (L ₂₎ none was 16 mm. (Example 1) Using the eutectic bonding apparatus (A), bonding was performed based on the method of the first embodiment described above.

The fitted copper pipe (1) and aluminum pipe (2) are restrained by restraining jigs (3a) (3b), and a pushing force (F) 3
At the same time as the application of 00N, the heaters (5) and (5) were energized to start heating. When the temperature of the heaters (5) and (5) was set so that the actual temperature of the restraining jigs (3a) and (3b) was 590 ° C, both pipes were set.
The actual temperature of (1) and (2) was increased and stabilized at about 580 ° C. During this time, the contact portions of the two pipes (1) and (2) melted, and the copper pipe (1) was pressed into the aluminum pipe (2) by the pressing force (F) already applied. When the press-fit amount (L ₂ ) reaches a predetermined value, the application of the pushing force (F) is cut off, and the power supply to the heaters (5) and (5) is cut off, and immediately the air blow (BW1) (BW2)
Cooled both pipes (1) and (2). At this time, pipe (1) (2)
The time required for the actual temperature of the sample to drop from 580 ° C to 500 ° C was 7 to 15 seconds. (Example 2) Using the eutectic bonding apparatus (B), bonding was performed based on the method of the above-described second embodiment.

The coil (16) used had an inner diameter of 14 mm and a length of 46 mm in the assembled state of the restraining jigs (13a) and (13b). The operating conditions were 200 kHz, 100 V, and 11 kW. . The insulator (15) used was a ceramic having a thickness of 3 mm and a semicircular cross section.

With the fitted copper pipe (1) and aluminum pipe (2) restrained by restraining jigs (13a) and (13b) via an insulator (15), the coil (16) is energized. Both pipes (1) and (2) were heated, and when the actual temperature reached 580 ° C., a pushing force (F) of 300 N was applied, and the copper pipe (1) was pressed into the aluminum pipe (2). When the press-fit amount (L ₂ ) reached a predetermined value, the application of the pressing force (F) and the energization to the coil (16) were stopped. After turning off the coil (16), pipes (1) and (2)
The time required for the actual temperature of the sample to drop from 580 ° C. to 500 ° C. was about 1 second, and the joined pipe was quickly cooled. (Example 3) Using the eutectic bonding apparatus (B), bonding was performed based on the method of the third embodiment described above.

The coil (16) and the insulator (15) were used in the second embodiment.
The same conditions were used.

With the fitted copper pipe (1) and aluminum pipe (2) restrained by restraining jigs (13a) and (13b) via an insulator (15), a pushing force (F) of 300N is applied. At the same time, the coil (16) was energized to start heating both pipes (1) and (2).
The actual temperature of the two pipes (1) and (2) rises and stabilizes at 580 ° C. During this time, the contact portion of the two pipes (1) and (2) melts and the copper Pipe (1) was pressed into aluminum pipe (2). When the press-fit amount (L ₂ ) reached a predetermined value, the application of the pushing force (F) was stopped and the energization to the coil (16) was stopped. After turning off the current to the coil (16), the actual temperature of the pipes (1) and (2) rises from 580 ° C to 50 ° C.
The time to drop to 0 ° C. was about 1 second, and the joined pipe was quickly cooled.

With respect to the joined pipes eutectic joined by the above three methods, appearance after joining, leakage test, pressure test, destructive test, tensile test, cooling test, bending test, heat test, salt spray test, vibration test, copper Pipe bending test, pinch test,
A torsion test and the like were performed. As a result, we were able to obtain satisfactory test results for all items.

[0045]

As described above, according to the first eutectic joining method for copper-aluminum pipes of the present invention, the tapered tapered portion formed at one end of the copper pipe has an open end at one end of the aluminum pipe. In a method of heating a fitting portion of both pipes to melt a contact portion and press-fitting a copper pipe into an aluminum pipe to perform eutectic joining, the fitting portion of the both pipes is restrained with a restraining jig. By pressing from the outside in the radial direction and heating the fitting portion in a state where a pressing force in the fitting direction is applied to both pipes before softening and melting the contact portion, the press-fitting is performed with the softening and melting of the contact portion. Is started, the molten state at the time of press-fitting is constant regardless of the temperature rise rate of the pipe, and poor joining and uneven bonding strength due to insufficient melting and excessive melting at the time of press-fitting are suppressed, resulting in good joining. Is done.

Further, in the second eutectic joining method of copper-aluminum pipes, the fitting portion of the two pipes is restrained from outside in the radial direction by a restraining jig via an insulator, and Since the fitted part generates heat and the eutectic melting of the contact part by the placed high-frequency induction coil, the pipe is heated directly without the intervention of a restraining jig. After the joining, the joint is cooled quickly to suppress the growth of the eutectic, and a good joining is achieved.
In addition, since heating and cooling are performed without overlapping,
In any of the steps, good bonding is achieved with stable temperature conditions.

Further, in the third eutectic joining method of the copper-aluminum pipe, the fitting portion of the two pipes is restrained from the outside in the radial direction with a restraining jig via an insulator, and the contact portion is softened and melted. In the state where the pushing force in the fitting direction has been previously applied to both pipes, the fitting portion is heated by the high-frequency induction coil arranged via the insulator, thereby softening and melting the contact portion. Since the press-fitting is started, the molten state at the start of the press-fitting is constant irrespective of the slow rate of the temperature rise of the pipe. Since the pipe is heated directly without using a jig, the heating of the pipe is immediately interrupted by cutting off the current to the coil, and after joining, it is cooled quickly to suppress the growth of eutectic and achieve good joining. Is done. In addition, since heating and cooling are performed without overlapping, the temperature condition is stable in any of the steps, and good bonding is achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of an eutectic joining apparatus for applying a eutectic joining method for pipes according to a first embodiment of the present invention, and a setting state of pipes.

FIG. 2 is a longitudinal sectional view showing a press-fit state of a copper pipe into an aluminum pipe in the first embodiment.

FIG. 3 is a longitudinal sectional view showing a configuration of an eutectic joining apparatus for applying a eutectic joining method of pipes according to second and third embodiments of the present invention, and a setting state of pipes.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is an explanatory diagram of generation of a eutectic junction.

[Explanation of symbols]

 A, B: eutectic bonding apparatus 1: copper pipe 1a: tapered part 2: aluminum pipe 2a: open end 3a, 3b, 13a, 13b: restraining jigs 4a, 4b, 14a, 14b: groove 15: insulator 16 ... High frequency induction coil

Continued on front page F term (reference) 3K059 AA08 AB23 AC33 AC76 AD01 AD05 CD66 4E067 AA05 AA07 BA05 CA04 DA17 DB03 DC01 DC06 EA04 EB01 EC06

Claims (3)

[Claims] An outer end (2a) of an aluminum pipe (2) is externally fitted to a tapered portion (1a) formed at one end of a copper pipe (1). In the method of heating the fitting portion of (2) to melt the contact portion, press-fitting the copper pipe (1) into the aluminum pipe (2) and performing eutectic joining, the two pipes (1) and (2) The fitting part is constrained from the outside in the radial direction by the constraining jigs (3a) and (3b).
(1) The press-fitting is started in conjunction with the softening and melting of the contact portion by heating the fitting portion in a state where the pressing force (F) in the fitting direction is applied in advance to (2). Eutectic joining method for copper-aluminum pipes. 2. An outer end (2a) of an aluminum pipe (2) is externally fitted to a tapered portion (1a) formed at one end of a copper pipe (1). In the method of heating the fitting portion of (2) to melt the contact portion, press-fitting the copper pipe (1) into the aluminum pipe (2) and performing eutectic joining, the two pipes (1) and (2) The fitting portion is restrained from outside in the radial direction by restraining jigs (13a) (13b) via the insulator (15), and the insulator
A eutectic joining method for a copper-aluminum pipe, characterized in that a fitting portion is heated by a high-frequency induction coil (16) arranged via (15) to melt a contact portion. 3. An outer end (2a) of one end of an aluminum pipe (2) is externally fitted to a tapered portion (1a) formed at one end of a copper pipe (1). In the method of heating the fitting portion of (2) to melt the contact portion, press-fitting the copper pipe (1) into the aluminum pipe (2) and performing eutectic joining, the two pipes (1) and (2) The fitting portion is restrained from outside in the radial direction by restraining jigs (13a) (13b) via the insulator (15), and
Before the softening and melting of the contact portions, the high-frequency induction coils (16) arranged via the insulator (15) in a state where a pressing force (F) in the fitting direction is applied to both pipes (1) and (2) in advance. ), The press-fitting is started along with the softening and melting of the contact portion by generating heat in the fitting portion, whereby the eutectic joining method of the copper-aluminum pipe is performed.