JPH0350621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of connecting a copper tube and an aluminum tube, which is used when connecting a copper tube to a refrigerant tube of an aluminum cooler, for example, 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 copper pipes and aluminum pipes (refrigerant pipes of coolers), joints in which short copper 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 a method in which a copper tube and an aluminum tube are fitted and joined by soldering. In this method, solder is applied in advance to the outer circumferential surface of the end of the copper tube and the inner circumferential surface of the end of the enlarged diameter aluminum tube, and the copper tube end is fitted inside the aluminum tube end in advance. In this fitted state, the solder is heated and melted while applying ultrasonic vibrations from the copper tube side, thereby joining the two tubes. 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 them together, and this results in This increases the clearance between the fitting part and the fitting part, which is unfavorable in terms of joint strength, requires a large amount of solder, and makes it difficult to fill the entire fitting part with solder, which may cause refrigerant leakage.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and
The purpose of this method is to provide strong joint strength, use less solder, and fill the entire mating part with solder to prevent refrigerant leakage in the method of fitting copper pipes and aluminum pipes and joining them with solder. It is an object of the present invention to provide a method for connecting a copper pipe and an aluminum pipe without the risk of such occurrence.

[Summary of the invention]

The present invention provides an aluminum tube in which an enlarged diameter part is formed at the end and solder is attached to the inner circumferential surface of the enlarged diameter part, and an aluminum tube in which solder is attached to the outer circumference of the end and the outer diameter of the soldered outer circumference is When connecting copper pipes with a diameter larger than the inner diameter of the inner peripheral surface, solder is attached to the ends of both pipes in the process before fitting the copper pipe and aluminum pipe. The solder is heated and melted, and in this state, pressure is applied to the copper tube and the aluminum tube while applying ultrasonic vibrations, so that the ends of both tubes are press-fitted together, and the tip of the copper tube is inserted into the expanded aluminum tube. The inner part of the expanded diameter part is expanded by applying pressure to the inner part of the diameter part, which allows the two pipes to be tightly fitted, improving joint strength and reducing the amount of solder used. In addition to achieving
Ultrasonic vibrations fill the entire mating area with solder to reliably prevent fluid leakage, and even if the strong copper tube is fitted inside the aluminum tube, it is a tight fit. By preventing the pipe from deforming in the direction of narrowing the inner diameter when mating, and by heating the aluminum pipe when mating, the solder is scraped out from the mating area when the copper pipe is fitted. This also prevents it from solidifying into water droplets.

[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. The tip of this copper tube 1 is tapered 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
In this example, the A dimension is set to be equal to or slightly smaller than the outer diameter dimension B.
It is set approximately 0.05 to 0.1 mm smaller than the dimensions. This is done when performing so-called ultrasonic soldering, which will be described later, on the inner peripheral surface of the aluminum tube 2.
is eroded by the ultrasonic waves, so the thickness is set to be smaller in consideration of the thickness of the erosion (approximately 0.05 to 0.1 mm). Further, the length C of the enlarged diameter portion 2a is set to be slightly shorter than the fitted length D (see Fig. 10) when the copper tube 1 and the aluminum tube 2 are fitted as described below. are doing. Next, FIGS. 3 and 4 show an ultrasonic soldering device for attaching solder to a copper tube 1 and an aluminum tube 2, respectively. A diaphragm 6 connected to the sonic vibrator 5 is provided. Further, the copper pipe 1 and aluminum pipe 2 immersed in the molten solder 7 in the bathtub 4 are as follows:
They are connected to blow pipes 10 and 11 connected to an air compressor (not shown) via electromagnetic valves 8 and 9, respectively. The blow pipe 10 on the side of the copper pipe 1 is also connected to the air compressor via the pressure reducing valve 12, and the blow pipe 10 on the side of the aluminum pipe 1
The side blow pipe 11 is open to the atmosphere by forming a small hole 11a. By the way, as the solder 7, we used aluminum solder with 95% Zn and 5% Al, and the heating temperature of the solder 7 was approximately 415℃ on the copper tube 1 side.
The temperature is adjusted to maintain approximately 440°C on the aluminum tube 2 side. FIG. 5 shows a pipe connecting device, in which a holder 1 holding an aluminum pipe 2 is shown.
A pressure jig 14 for holding the copper tube 1 is provided above the pipe 3 so as to be movable up and down, and an ultrasonic vibrator 15 is further provided above the pressure jig 14. Also, between these holders 13 and the pressurizing jig 14, there is a copper pipe 1.
A plurality of gas burners 16 and 17 for heating the ends of 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 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 closing the solenoid valves 8 and 9. The end portions of both tubes 1 and 2 are immersed in molten solder 7 as shown in FIGS. 3 and 4 while the ultrasonic vibrator 5 is being 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 intrude into the inside of the copper pipe. Since the air inside the blow pipe 11 escapes into the atmosphere through the small hole 11a of the blow pipe 11, the molten solder 7 enters the inside of the aluminum pipe 2, and eventually the copper pipe 1
The molten solder 7 adheres only to the outer peripheral surface of the end portion, and the molten solder 7 adheres to both the inner and outer peripheral surfaces of the end portion of the aluminum tube 2. At this time, since ultrasonic waves (about 18 KHz) are applied to the molten solder 7 by the diaphragm 6, so-called cavitation occurs and countless small vacuum nuclei are generated in the molten solder 7, and when these nuclei disappear, The instantaneous 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 7, 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 "drops" is blown away by compressed air.
Prevents solder from solidifying into "drops" and remaining. In addition, in order to secure the amount of solder necessary for joining, the copper tube 1 is dipped into the molten solder 7 described above once again (the second immersion depth is slightly shallower than the first time), and the aluminum tube Regarding No. 2, it is preferable to perform the above-mentioned air blowing twice in order to equalize the solder adhesion thickness on the inner circumferential surface.

Now, as described above, the thin solder layer 1 is applied to the end.
As shown in FIG. 5, the copper tube 1 and aluminum tube 2 to which the tubes 8 and 19 are attached are held in a pressure jig 14 and a holder 13 so as to face each other vertically, and then the pressure jig 14 is lowered. As shown in FIG. 6, 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 at this time is too large, the copper tube 1 will be pushed into the aluminum tube 2 when one of the solder layers 18 or 19 melts, and a good bond will not be obtained. , the pressure is assumed to be extremely weak. Then, both solder layers 18 and 1
9 melts, gas burners 16 and 17
While continuing heating, the ultrasonic vibrator 15 is driven and the pressure jig 14 is used to press down the copper tube 1 with a strong pressing force, and the end of the copper tube 1 is pressed down to the aluminum tube 2 as shown in FIG. Fit inside the end. The amount of depression of the copper tube 1 at this time is
The lower part of the enlarged diameter part 2a of the aluminum pipe 2 (the enlarged diameter part 2
Make sure to spread out the part farther back than a. When the end of the copper tube 1 is press-fitted into the enlarged diameter portion 2a of the aluminum tube 2 in this way, since ultrasonic vibration is applied to the copper tube 1, the outer diameter of the copper tube 1 is Even though the inner diameter is larger than the inner diameter of the aluminum tube 2, the copper tube 1 is smoothly fitted into the aluminum tube 2 with a relatively small pressing force, and then the tip of the copper tube 1 is inserted under the enlarged diameter part 2a of the aluminum tube 2. The area can be expanded. The expansion of the diameter of the aluminum tube 2 by the copper tube 1 brings the two tubes 1 and 2 into strong contact. and the aluminum tube 2 was soldered during ultrasonic soldering.
Even if the copper tube 1 is eroded, the ultrasonic vibrations applied to the copper tube 1 from the ultrasonic vibrator 15 are not applied to the aluminum tube 2 as the tubes 1 and 2 are tightly fitted with an extremely small clearance. This ultrasonic vibration causes the molten solder in both solder layers 18 and 19 to mix well, and the wettability of the molten solder to the copper tube 1 and the aluminum tube 2 increases, thereby reducing the entire clearance between the two tubes 1 and 2. is completely filled. By the way, when the copper tube 1 is fitted into the enlarged diameter section 2a of the aluminum tube 2, the solder on the inner circumference of the enlarged diameter section 2a is squeezed into the copper tube 1 and a part of it is scraped out from the fitting part with the copper tube 1. As a result, as shown in FIG. 8, it becomes a water droplet. However, in this fitting process, since the expanded diameter portion 2a of the aluminum tube 2 continues to be heated by the gas burner 17, the expanded diameter portion 2a of the aluminum tube 2 continues to be heated.
The temperature in the lower part of a is also quite high. Therefore, the solder scraped out from the fitting portion spreads in a thin film over the inner circumferential surface of the aluminum tube 2 while remaining molten, as shown in FIG. Therefore, it is possible to prevent the scraped out solder from solidifying in the form of water droplets as shown in Figure 8, so that the solder solidified in the form of water droplets may narrow the pipes and obstruct the flow of the refrigerant. This prevents the inconvenience of breaking during use and getting mixed into the refrigerant, causing malfunctions of the refrigeration cycle's on-off valve and compressor.

After fitting both the tubes 1 and 2 as described above, ultrasonic vibration is applied and the gas burners 16, 1
7 is stopped and the solder is solidified by natural cooling, thereby joining the copper tube 1 and the aluminum tube 2 as shown in FIG.

〔Effect of the invention〕

As explained above, the present invention heats and melts the solder that has been attached in advance to the end of the copper tube and the enlarged diameter end of the aluminum tube, and then applies ultrasonic vibration to the copper tube and the aluminum tube. While applying pressure, the end of the copper tube is press-fitted into the enlarged diameter part of the aluminum pipe, and the tip of the copper pipe is further pressurized further than the enlarged diameter part of the aluminum pipe to expand the inner part of the enlarged diameter part. Because the diameter is increased, the copper tube can be fitted smoothly into the aluminum tube with a relatively small pressure force, and both tubes can be fitted closely, improving the joint strength. Since the clearance between the two tubes is extremely small, the amount of solder used is reduced, and the solder fills the entire fitting portion by ultrasonic vibration, so fluid leakage can be reliably prevented. In addition, since the strong copper tube is fitted inside the aluminum tube, even if it is a tight fit, the tube will not be deformed in the direction of narrowing the inner diameter during the fitting, and fluid flow will be improved. There is no risk of harm to Moreover, since the aluminum tube is heated when the two tubes are mated, even if the solder on the inner circumferential surface of the aluminum tube is scraped out from the mating area by the copper tube, the scraped solder will melt. In this state, the solder may spread into a thin film on the inner circumferential surface of the aluminum pipe, and there is a risk that the scraped out solder may solidify into water droplets and narrow the pipe, or may break and get mixed into the fluid. It has excellent effects such as no blemishes.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a front view of a copper tube and an aluminum tube, 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 soldering device, FIG. 5 is a longitudinal sectional view of the pipe connecting device, and FIGS. 6 to 10 are longitudinal sectional views sequentially showing the connection process. In the figure, 1 is a copper tube, 2 is an aluminum tube, 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 and 17 are gas burners, and 18 and 19 are solder layers.

Claims (1)

[Claims] 1 An aluminum tube with an enlarged diameter section formed at the end and solder attached to the inner circumferential surface of this enlarged diameter section, and an aluminum tube with solder attached to the outer circumferential surface of the end and the outer diameter of the soldered outer circumferential surface A process of butting together copper tubes whose inner diameter is larger than the inner diameter of the inner circumferential surface of the solder joints, a process of heating and melting the solder at the ends of the copper tubes and aluminum tubes while they are butted together, and a process of heating and melting the solder at the ends when the solder is melted. While the aluminum tube is heated, pressure is applied while applying ultrasonic vibration to the copper tube and the aluminum tube, and the end of the copper tube is press-fitted inside the enlarged diameter part of the aluminum tube, and then the tip of the copper tube is pressed into the aluminum tube. A copper pipe comprising a step of inserting pressure to the back of the expanded diameter portion of the pipe to expand the diameter of the expanded diameter portion of the tube, and a step of cooling and solidifying the solder by stopping ultrasonic vibration and heating after fitting. How to connect with aluminum pipe.