JPS60154870A - Method for connecting copper pipe and aluminum pipe - Google Patents

Abstract

PURPOSE:To fit tightly a copper pipe and an aluminum pipe with satisfactorily packed solder without hindering the flow in the pipes and without change in the diameter thereof by sticking respectively the solder to the outside surface at the end of the copper pipe having a prescribed size and the inside surface at the end of the aluminum pipe, heating the ends and pressing and fitting the ends while oscillating ultrasonically the same. CONSTITUTION:Solder 18, 19 are stuck respectively by a suitable method to the outside surface at the end 1 of a copper pipe and the inside surface at the end 2 of an aluminum pipe having about 0.05-0.1mm. fitting clearance. The both ends 1, 2 are heated by burners 16, 17, etc. and are press-inserted and fitted to each other by a pressing jig 14; at the same time an ultrasonic oscillation 15 is applied to the ends to pack thoroughly the molten solder into the fitting part. The solder protruding to the inside is thinly spread to the inside wall surface of the pipe by heat and oscillation so that the flow in the pipe is not hindered. The two pipes 1, 2 are thus securely and tightly fitted and soldered to each other without change in the diameter thereof and without leakage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for connecting steel pipes and aluminum pipes, which is used, for example, when connecting a steel pipe 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 peripheral surface of the end of the steel pipe and the inner peripheral surface of the end of the aluminum pipe whose diameter has been expanded, and then the copper pipe end is fitted inside the aluminum pipe end in advance. In the fitted state, the two 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 vibrations fill the entire mating area with solder to reliably prevent fluid leakage, and the strong steel pipe is fitted inside the aluminum pipe to ensure 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 during mating, even if solder is scraped out of the mating area due to the fitting of the steel pipe, this will not occur. This 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. This copper pipe 1
The tip 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 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 It is set 0.1111m smaller. This is because when performing so-called ultrasonic solder plating, which will be described later, on the inner peripheral surface of the aluminum tube 2, the aluminum tube 2 is eroded by the ultrasonic waves.
0.11111) and set it smaller accordingly. 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 solder plating apparatus for attaching solder to a copper tube 1 and an aluminum tube 2, respectively. A diaphragm 6 connected to the vibrator 5 is provided. Also, the copper tube 1 immersed in the molten solder 7 in the bath 4 . The aluminum pipes 2 are adapted to be connected via solenoid valves 8.9 to blowpipes 10.11, respectively, which are connected to a near compressor (not shown). and,
The blow pipe 1o on the copper pipe 1 side is also connected to the near compressor via a pressure reducing valve 12, while the blow pipe 11 on the aluminum pipe 2 side is open to the atmosphere by forming a small hole 11a. By the way, solder 7 is 7995%,
Use AZ'5% aluminum solder, solder 7
The heating temperature is approximately 415℃ on the copper tube 1 side, and on the aluminum tube 2 side.
The temperature is adjusted to maintain approximately 440°C at the side. Then,
FIG. 5 shows a pipe connection 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 so as to be movable up and down.
An ultrasonic transducer 15 is provided on the top of the . Further, between the holder 13 and the pressurizing jig 14, a gas burner 16 is installed to heat the ends of the copper tube 1 and the aluminum tube 2.
．． A plurality of 17 are provided in upper and lower two stages.

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. 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 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. At this time, the molten solder 7
Since ultrasonic waves (approximately 18KH2) are applied 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 Copper pipe 1 and aluminum pipe 2
Dirt and oxide film on the surface are removed, forming a uniform plating layer, and the ultrasonic waves increase the fluidity of the molten solder 7, promoting wetting and improving plating properties. and,
After this immersion, both tubes 1 and 2 are pulled out of the molten solder 7,
At the same time as this lifting, the solenoid valves 8 and 9 are opened to blow compressed air out of the copper pipe 1 and the aluminum pipe 2 through the blow pipes 10 and 11.

As a result, the solder hanging down from the bottom ends of both tubes 1 and 2 like "drops" is blown away by compressed air, and the solder is
Prevents it from solidifying into drops and remaining. In addition, copper pipe 1
In order to ensure the amount of solder necessary for bonding, the above-mentioned immersion into the molten solder 7 is performed once more, and the depth of the second immersion is made slightly shallower than the first time. ), 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.
The copper tube 1 and the aluminum tube 2 to which 9 has been attached are held in a pressure jig 14 and a holder 13, respectively, as shown in FIG. 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 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. And both solder layers 1
When gas burners 8 and 19 are melted, gas burners 16 and 1
While continuing the heating by 7 and driving the ultrasonic vibrator 15, the pressing jig 14 presses down the copper tube 1 with a strong pressing force, and the end of the copper tube 1 is pressed down into an aluminum tube as shown in FIG. Fit it inside the end of 2. 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 copper tube 1 has greater strength than aluminum.
The lower part of the enlarged diameter part 2a of the aluminum tube 2 is pushed out. 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. Even if the aluminum tube 2 is eroded during ultrasonic solder plating, the tubes 1 and 2 are tightly fitted with an extremely small clearance, so that the ultrasonic wave vibrator 15 can not apply any force to the copper tube 1. The ultrasonic vibrations generated are effectively transmitted to the aluminum tube 2, and this ultrasonic vibration increases the wettability of the molten solder in both solder layers 18 and 19, so that the entire clearance between the tubes 1 and 2 is completely filled. Ru. 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, the enlarged diameter part 2a of the aluminum tube 2 continues to be heated by the gas burner 17, so the lower part of the enlarged diameter part 2a is also at an extremely high temperature. . Therefore, the solder scraped out from the mating part is
As shown in the figure, it spreads in a thin film shape on the inner peripheral surface of the aluminum tube 2 in a molten state. Therefore, the scraped out solder
As shown in the figure, it is possible to prevent the solder from solidifying in the form of water droplets, so that the solder solidified in the form of water droplets may narrow the pipes and obstruct the flow of the refrigerant, or break during actual use and get mixed into the refrigerant, causing the refrigeration cycle. It is possible to prevent inconveniences such as malfunctions of on-off valves and compressors.

After fitting the tubes 1 and 2 together as described above, the application of ultrasonic vibration and the heating by the gas burners 16 and 17 are stopped, and the solder is solidified by natural cooling, as shown in Fig. 10. Copper tube 1 and aluminum tube 2 are joined.

〔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, since a high-strength steel pipe is fitted inside the aluminum pipe, even if it is a tight fit, the pipe will not be deformed in the direction of narrowing the inner diameter, and the flow of fluid will be prevented. There is no risk of harm. 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 steel tube, the scraped solder remains molten. As it is, the solder will spread like a thin film on the inner circumferential surface of the aluminum pipe, and there is a risk that the scraped solder will solidify into water droplets and narrow the pipe, or break and get mixed into the fluid. It has excellent effects such as:

[Brief explanation of drawings]

The drawings show an 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 soldering. FIG. 5 is a longitudinal sectional view of the plating apparatus, 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 steel pipe, 2 is an aluminum pipe, 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, 1
8.19 is a solder layer. Applicant: Tokyo Shibaura Electric Co., Ltd. Figure 1 Isamu 3 Figures 4 to 15 Engineering ← 1 to B Figure 7 Figure 9 Figure 10

Claims (1)

[Claims] 1. The process of butting together a copper tube with solder attached to the outer peripheral surface of the end and an aluminum tube with solder attached to the inner peripheral surface of the end, and The process of heating and melting the solder, and applying pressure while applying ultrasonic vibrations to the steel pipe and aluminum pipe while heating the aluminum pipe while melting the solder, pressurizes the end of the steel pipe inside the end of the aluminum pipe. A method for connecting steel pipes and aluminum pipes, which comprises a fitting process, and a process of cooling and solidifying the solder by stopping the application of ultrasonic vibration and heating after fitting.