JPS60154871A - Method for connecting copper pipe and aluminum pipe - Google Patents

Abstract

PURPOSE:To fit tightly and solder a copper pipe and an aluminum pipe with a good oscillating effect by sticking respectively solder to the outside surface at the end of the copper pipe having a prescribed size and the inside surface of the aluminum pipe of which the fitting and expanding length is shorter than the prescribed length, heating the ends and pressing and fitting the ends under the ultrasonic oscillation applied thereto. CONSTITUTION:Solder 18, 19 are respectively stuck by a suitable method to the outside surface at the end of a copper pipe having about 0.05-0.1mm. fitting clearance and the inside surface at the end 2 of an aluminum pipe of which the fitting and expanding length is shorter than a prescribed length D. The both ends 1, 2 are heated by burners 16, 17, etc. and are press-inserted and fitted to each other to the length D; at the same time an ultrasonic oscillation 15 is applied thereto and the effect thereof is made extremely effective by the strong press contact of the pipes 1, 2 so that the molten solder is thoroughly diffused and packed between the pipes. The pipes 1, 2 are thus securely and tightly fitted and soldered to each other without leakage and change in the diameter thereof and without hindering the flow in the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for connecting copper pipes and aluminum pipes, which is used when, for example, a steel pipe is connected to a refrigerant pipe of an aluminum cooler in a refrigerator.

[Technical background of the invention and its problems]

For example, in a refrigerator, the refrigeration cycle piping is made of materials such as copper, aluminum, and iron, and is connected by a joining method suitable for each material.

Conventionally, for connecting steel pipes and aluminum pipes (refrigerant pipes of coolers), joints in which short steel pipes and aluminum pipes are flash welded, butt welded, or explosively welded have been used. However, this joint is expensive and requires TIG welding, which requires a high level of skill, when connecting the aluminum pipe of the joint and the aluminum pipe of the cooler. As a connection method to solve this problem,
There is one in which a steel pipe and an aluminum pipe are fitted and joined by soldering. In this method, solder is applied in advance to the outer circumferential surface of the end of the steel pipe and the inner circumferential surface of the end of the aluminum pipe whose diameter has been enlarged, and the end of the steel pipe is fitted inside the end of the aluminum pipe in advance. Under this condition, both tubes are joined by applying ultrasonic vibrations from the copper tube side and heating and melting the solder. However, with this method, since solder is applied to both tubes in advance, the end of the aluminum tube must be enlarged considerably in diameter in order to fit the two together. This increases the clearance, which is not desirable in terms of joint strength, requires a large amount of solder, and makes it difficult to fill the entire fitting portion with solder, which may cause refrigerant leakage.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of fitting and joining a steel pipe and an aluminum pipe with solder, which provides strong joint strength, uses a small amount of solder, and provides a method for fitting and joining a steel pipe and an aluminum pipe. It is an object of the present invention to provide a method for connecting a steel pipe and an aluminum pipe in which there is no risk of refrigerant leakage due to the entire joint being filled with solder.

[Summary of the invention]

The present invention heats and melts the solder previously attached to the ends of both tubes in the process before fitting the steel tube and the aluminum tube together, and in this state applies ultrasonic vibrations to the steel tube and the aluminum tube. The end portions of both tubes are press-fitted to each other by pressure, which allows both tubes to be tightly fitted, improving joint strength and reducing the amount of solder used. Ultrasonic vibration fills the entire mating part with solder to reliably prevent fluid leakage, and also allows the strong steel pipe to be fitted inside the aluminum pipe, while also making it possible to fit the high-strength steel pipe inside the aluminum pipe. The tube has an enlarged diameter section at the end, and by setting the length of the enlarged diameter section to be shorter than the final mating length of both tubes, the tubes can be In addition to preventing deformation in the direction of narrowing the inner diameter, the aluminum tube is forced wider by the steel tube during the fitting process, so that the two tubes come into strong contact and the ultrasonic vibrations applied to one tube are transferred to the other tube. It is designed so that it can be effectively transmitted even to the pipes of the pipes.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on the drawings.

First, FIGS. 1 and 2 show a copper tube 1 and an aluminum tube 2 (refrigerant tubes of a cooler) that are connected to each other. This copper pipe 1
The tip end is tapered into a tapered shape so that the diameter gradually decreases. On the other hand, the end of the aluminum tube 2 is expanded in diameter, and the tip of the expanded diameter portion 2a is expanded in a tapered shape so that the diameter gradually increases. In this case, the inner diameter dimension A of the enlarged diameter portion 2a is set to be equal to or slightly smaller than the outer diameter dimension B of the copper tube 1, and in this embodiment, the diameter dimension is approximately 0.05 to 0. Hnm is set small. This is because the aluminum tube 2 is eroded by the ultrasonic waves when performing so-called ultrasonic solder plating, which will be described later, on the inner peripheral surface of the aluminum tube 2, so the erosion thickness is approximately 0.05~Q,
1n+m), and is set smaller accordingly. Further, the length C of the enlarged diameter portion 2a is slightly shorter than the final fitted length D (see Fig. 9) when the copper tube 1 and the aluminum tube 2 are fitted as described below. It is set. Incidentally, in this embodiment, the final fitting length is set to iQmm, and the length C of the enlarged diameter portion 2a is set to 5 to 5.
It is set to 8mm. Next, FIGS. 3 and 4 show an ultrasonic solder plating device for attaching solder to a copper tube 1 and an aluminum tube 2, respectively. A diaphragm 6 connected to the child 5 is provided. Also, the molten solder 7 in the bathtub 4
Copper tube immersed in 1. The aluminum pipes 2 are connected via solenoid valves 8, 9, respectively, to blowpipes 10, 11 connected to a near compressor (not shown). The blow pipe 10 on the copper pipe 1 side is connected to the pressure reducing valve 12.
The blow pipe 11 on the other side of the aluminum tube 2 is also connected to the near compressor via a small hole 11a, and is open to the atmosphere. By the way, as the solder 7, use 2□95%, AI 5% aluminum solder, and adjust the heating temperature of the solder 7 to maintain approximately 415°C on the copper pipe 1 side and approximately 440°C on the aluminum pipe 2 side. be done. FIG. 5 shows a pipe connecting device, in which a pressure jig 14 for holding a copper pipe 1 is provided above a holder 13 for holding an aluminum pipe 2, and is movable up and down. An ultrasonic vibrator 15 is provided on the top of the pressing jig 14. Further, between the holder 13 and the pressurizing jig 14, a plurality of gas burners 16 and 17 for heating the ends of the copper tube 1 and the aluminum tube 2 are provided in upper and lower two stages, respectively.

Next, the procedure for connecting the copper tube 1 and the aluminum tube 2 will be explained. To do this, first apply some solder to the ends of both tubes 1 and 2. This involves connecting the copper tube 1 and aluminum tube 2 to the blow pipes 10 and 11, respectively, and then connecting the solenoid valves 8 and 9. This is done by immersing the ends of both tubes 1 and 2 in molten solder 7, as shown in FIGS. 3 and 4, with the tubes closed and the ultrasonic vibrator 5 driven. Then,
Since low-pressure compressed air is supplied into the copper pipe 1 through the pressure reducing valve 12 and the blow pipe 10, the internal pressure of the copper pipe 1 will not increase and the molten solder 7 will not infiltrate into the interior of the copper pipe 1, and on the other hand, the aluminum pipe 2 Since the air inside escapes into the atmosphere through the small hole 11a of the blow pipe 11, the molten solder 7
will enter the inside of the aluminum tube 2, and in the end, the molten solder 7 will adhere only to the outer peripheral surface of the end of the copper tube 1.
As for the aluminum tube 2, the molten solder 7 will adhere to both the inner and outer peripheral surfaces of the end portion. This sharpening molten solder 7
Since ultrasonic waves (approximately 18 Kl-12) are applied by the diaphragm 6, so-called cavitation occurs and countless small vacuum nuclei are generated in the molten solder 7, and the moment when these nuclei decrease in volume, The force removes dirt and oxide films on the surfaces of the copper tube 1 and aluminum tube 2, forming a uniform plating layer, and the ultrasonic waves increase the fluidity of the molten solder 7, promoting wetting. Improves plating properties. After this immersion, both tubes 1 and 2 are pulled up from the molten solder γ, and at the same time as they are pulled up, the solenoid valves 8 and 9 are opened to blow compressed air out of the copper tube 1 and the aluminum tube 2 through the blow pipes 10 and 11.

As a result, the solder hanging down from the lower ends of both tubes 1 and 2 like a drop J is blown away by compressed air, and the solder is
Prevents it from solidifying into drops and remaining. The copper pipe 1 is dipped into the molten solder 7 once again, and the depth of the second immersion is made slightly shallower than the first time in order to ensure the solder green necessary for joining. ), for the aluminum tube 2, it is preferable to perform the above-mentioned air blowing twice in order to equalize the thickness of solder adhesion on the inner circumferential surface.

Now, as described above, the thin solder layers 18 and 1 are applied to the ends.
As shown in FIG. 5, the copper tube 1 and the aluminum tube 2 to which No. 9 is attached are held in a pressure jig 14 and a holder 13, respectively, so as to face each other vertically, and then the pressure jig 14 is lowered and a sixth As shown in the figure, the lower end of the copper tube 1 is butted against the upper end of the aluminum tube 2 with a weak pressure. Next, under this butt condition, the gas burners 16 and 17 are connected as shown in FIG.
The ends of both tubes 1 and 2 are heated to melt their solder layers 18 and 19. Note that if the pressure applied to the copper tube 1 is too large at this time, the copper tube 1 will be pushed into the aluminum tube 2 when one of the solder layers 18 or 19 melts, making it impossible to obtain a good bond. C1 The pressing force is extremely weak. And both solder layers 1
8 and 19 are melted, the pressure jig 14 is used to press down the copper tube 1 with strong pressure while driving the ultrasonic vibrator 15, and the end of the copper tube 1 is pressed down to the aluminum tube 2 as shown in FIG.
Fit inside the end. At this time, the amount of depression of the copper tube 1 is made slightly larger than the length dimension C of the enlarged diameter part 2a of the aluminum tube 2, so that the aluminum tube 2 is pushed down by the copper tube 1, which is stronger than aluminum. The lower part of the enlarged diameter part 2a is pushed out. By expanding the diameter of the aluminum tube 2 by the copper tube 1, both tubes 1 and 2 come into strong contact.
In addition to this, the inner diameter of the enlarged diameter portion 2a of the aluminum tube 2 is preset smaller than the outer diameter of the copper tube 1, and even if the aluminum tube 2 is eroded during ultrasonic solder plating, both tubes 1 and 2 will be By closely fitting with a slight clearance, the ultrasonic vibrations applied to the copper tube 1 from the ultrasonic vibrator 15 are effectively transmitted to the aluminum tube 2, and this ultrasonic vibration causes both solder layers 18 and The wettability of the molten solder 19 is increased, and the entire clearance between the tubes 1 and 2 is completely filled. Thereafter, the application of ultrasonic vibration and the heating by the gas burners 16 and 17 are stopped, and the solder is allowed to solidify by natural cooling, thereby joining the copper tube 1 and the aluminum tube 2 as shown in FIG. 9.

〔Effect of the invention〕

As explained above, the present invention heats and melts the solder previously attached to the ends of a steel pipe and an aluminum pipe, and then pressurizes the steel pipe and aluminum pipe while applying ultrasonic vibrations to bond them together. Since the ends are fitted into each other, both tubes can be tightly fitted, improving joint strength. Furthermore, since the clearance between both tubes is extremely small, the amount of solder used is reduced, and ultrasonic Since the vibration fills the entire fitting portion with solder, fluid leakage can be reliably prevented. In addition, the steel pipe with high strength is fitted inside the aluminum pipe, and the aluminum pipe has an enlarged diameter part at the end for fitting, and the length of the enlarged diameter part is equal to the final length of both pipes. Since the length is set shorter than the fitting length, even if the fitting is tight, the pipe will not be deformed in the direction of narrowing the inner diameter during the fitting, and there is no risk of harming the fluid flow. During the fitting process, the aluminum tube is pushed wider by the steel tube, so both tubes come into close contact with each other, and the ultrasonic vibrations applied to one tube are effectively transmitted to the other tube.
As a result, the solder attached to both tubes is well subjected to ultrasonic vibration, and excellent effects such as further improvement in filling of the fitting portions of both tubes are achieved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a front view of a steel pipe and an aluminum pipe, Fig. 2 is an enlarged longitudinal cross-sectional view of the same end, and Figs. 3 and 4 are ultrasonic waves. FIG. 5 is a longitudinal sectional view of the solder plating apparatus, FIG. 5 is a longitudinal sectional view of the pipe connecting device, and FIGS. 6 to 9 are longitudinal sectional views sequentially showing the connection process. In the figure, 1 is a steel pipe, 2 is an aluminum pipe, 2a is an enlarged diameter part,
4 is a solder bath, 5 is an ultrasonic vibrator, 13 is a holder, 14 is a pressure jig, 15 is an ultrasonic vibrator, 16.17 is a gas burner, and 18.19 is a soldering chamber. Applicant Tokyo Shibaura Electric Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Scabbard 5 (branch) Figure 7 Scabbard 9

Claims (1)

[Claims] 1. The process of butting together a steel pipe with solder attached to the outer peripheral surface of the end and an aluminum pipe with solder attached to the inner peripheral surface of the end, and A process of heating and melting the solder, a process of compressing and fitting the end of the steel pipe inside the end of the aluminum pipe by applying pressure while applying ultrasonic vibration to the steel pipe and aluminum pipe while melting the solder, and after the fitting The process consists of cooling and solidifying the solder at the fitting part of the body tube and the aluminum tube.The end of the aluminum tube has an enlarged diameter part for fitting with the steel pipe, and the length of the enlarged diameter part is A method for connecting a steel pipe and an aluminum pipe, characterized in that the length is set shorter than the final fitting length of the pipe.