JPS6347422Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a centering fitting used in automatic welding machines for tube end seals of heat exchangers, for example, and is suitable for continuous welding, especially in automatic welding of small diameter pipes. This relates to centering metal fittings.

[Prior art]

The tube end seal welding method for heat exchanger tubes and tube sheets is as follows:
As shown in Fig. 1, a tube end fusion joint is commonly used, in which the end of a tube 2 inserted into a tube plate 1 is melted and welded, and in order to obtain a uniform weld 3, a centering metal fitting is attached to the tip of the welding machine. This method is used to center the welding point by inserting it inside the pipe.

Conventionally, the structure and material of the centering metal fittings are generally as shown in Fig. 2 to prevent contact with the welding part due to thermal expansion, and the centering metal fitting 4 is designed to keep the temperature of the welding machine cool and cool near the welding part. Copper alloys are used to mitigate the rise.

By the way, in small-diameter pipes, the section modulus of the centering fitting 4 is also small, and the centering fitting 4 bends due to the weight of the welding machine during welding, making it difficult to insert into the next pipe and making it difficult to replace the centering fitting 4. There may be cases where continuous welding is not possible.

In this case, it is conceivable to make the material of the centering fitting 4 high tensile strength steel that can withstand the weight of the welding machine.
As mentioned above, thermal expansion may cause the centering fitting to connect to the welded part, or the high heat of the welded part may be conducted to the welding machine, causing problems in welding work and making it impossible to obtain a sufficient welded part.

Due to the above-mentioned problems, an optimal centering fitting for use in pipe end seal welding of small diameter pipes has not been put into practical use.

[Purpose of invention]

In order to solve the above-mentioned problems, the present invention has developed a centering fitting that can sufficiently withstand the weight of the welding machine even for small diameter pipes.
It also has a structure that takes advantage of the characteristics of copper alloy, and is intended to enable continuous automatic welding of tube end seals for small diameter tubes without replacing centering fittings.

[Summary of the idea]

The structure of the centering fitting is made of high tensile strength steel and its surface is lined with copper alloy.The centering fitting does not bend under the weight of the welding machine even in small diameter pipes, and the characteristics of the copper alloy are fully utilized. It is characterized by a structure that takes advantage of the

[Embodiment of the invention] An embodiment of the invention will be described below with reference to FIG. 1 is a tube plate, 2 is a tube inserted and fixed in tube plate 1, 3 is a welded part of tube plate 1 and tube 2, and 5A is the main body of a centering fitting attached to the center position of the tip of the welding machine. The high tensile strength steel core 5B is a copper alloy coating material lining the surface of the core metal 5A, and therefore, the centering fitting 5 is constituted by the core metal 5A and the coating material 5B. A gas cup 6 is attached to the welding machine and rotates around the centering fitting 5.

In the above configuration, the thickness of the copper alloy that is the covering material 5B depends on the heat capacity of welding, but as an example, if the outer diameter of the tube 2 is about 20 mm, it is generally 2 mm.
Thickness or higher is desirable. Further, the copper alloy coating lining the surface of the core metal 5A is, for example,
It can be easily manufactured by coating A with a copper alloy by thermal spraying and finishing by machining. Furthermore, a copper alloy rod may be processed to fit the core metal 5A, then cut in half to fit the core metal 5A, and the half portions may be welded.

The centering fitting 5 is inserted into the pipe 2, the welding machine is centered, and the welded portion 3 is welded using the gas cup 6. In this case, since the core metal 5A is made of high tensile strength steel, the centering metal fitting 5 will not bend due to the weight of the welding machine even if the pipe 2 is a small diameter pipe, and the welded part 3 will be cooled by the coating material 5B, which is a copper alloy. Heat conduction to the welding machine is also reduced, allowing continuous welding.

[Effect of idea]

According to the present invention, automatic welding of tube end seals of small diameter tubes can be carried out continuously.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of a workpiece to which the present invention is applied, FIG. 2 is a cross-sectional view of a conventional centering fitting, and FIG. 3 is a cross-sectional view showing an embodiment of the present invention. 1...Tube sheet, 2...Pipe, 3...Welded part, 5...
Centering metal fitting, 5A...Core metal, 5B...Coating material, 6
...Gaskap.

Claims (1)

[Scope of utility model registration request] In the centering fittings of automatic pipe end seal welding machines,
A centering fitting for pipe end seal welding, characterized in that the core metal is made of high tensile strength steel that has enough strength to withstand the weight of a welding machine, and the outer peripheral surface of the core metal is lined with a copper alloy coating material.