JPS5939488A - Diffusion joining method of tubular product - Google Patents

Abstract

PURPOSE:To subject easily and surely tubular products to diffusion joining by inserting the 2nd pipe of a small diameter into the 1st pipe, installing a core having a large coefft. of linear expansion and a restraining ring having a small coefft. of linear expansion to the inside and outside of the insertion part and heating the same to a high temp. CONSTITUTION:The 2nd pipe 2 of copper or the like of a diameter smaller than the diameter of the 1st pipe 1 which is an iron pipe or the like is inserted into the 1st pipe. A restraining ring 7 consisting of a material of an Ni alloy or the like having the high temp. strength higher than the same strength of the pipes 1, 2 and the coefft. of linear expansion equal to or smaller than the coefft. of said pipes is installed on the outside surface of the pipe 1 in the insertion part. A core 6 consisting of a material such as SUS 304 having the high temp. strength higher than the strength of the pipes 1, 2 and the coefft. of linear expansion larger than the coefft. of said pipes is installed in the pipe 2 in the insertion part. These pipes, ring and core are heated to a high temp. Compressive force is generated between the pipes 1 and 2 by the expansion of the core 6 and the restraining of the ring 7, by which the pipes are easily diffusion joined 8.

Description

[Detailed Description of the Invention] Regarding the improvement of the diffusion bonding method for Fi tubular products of the present invention, it is an object of the present invention to provide a simple and reliable pressurizing method during diffusion bonding that effectively utilizes the thermal expansion of the fiber. be.

Conventionally, for pipe joints made of materials that are difficult to weld, as shown in Figure 1, pipe material 1 and pipe material 2 of a smaller diameter are inserted into a shape and brazed 3.
As shown in FIG. 2, the method used is to braze the tube charges 1 and 2 through the fitting 4 of the furnace tube.

Although improvements in strength and performance are sometimes claimed for the conventional method, for PIIft materials for which fusion welding is difficult, diffusion bonding is the only method other than brazing.

However, with diffusion welding, it is difficult to apply the necessary pressure to the joint, /)! This is especially true for small-diameter pipes.

The inventors of the present invention have conducted extensive research into methods for obtaining the necessary pressure when joining tubular products by expanding them, and have confirmed that the objective can be achieved by utilizing the thermal expansion of the material, and have developed the present invention. It has been completed.

In other words, the present invention provides a second pipe with a diameter smaller than the first one in a small pipe.
The first tube is inserted into the fitting portion, and the first tube is attached to the outer surface of the first tube of the insertion portion. The high temperature strength is higher than that of the second tube, and the coefficient of linear expansion is the first.
A restraining ring made of a material that is equal to or smaller than the tube of No. 1. Second
It has a higher high temperature strength than the tube of 1. The gist of the present invention is a diffusion bonding method for tubular products, which is characterized in that a core made of a material with a higher coefficient of linear expansion than the second tube is installed and heated to a high temperature.

The diffusion bonding method of the present invention can be advantageously applied to the Nureap installation of heat exchanger tubes in a steam generator and the joining of dissimilar tubes.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.

As shown in Figure 3, iron W1 (linear expansion coefficient 11.7
10-'/'C High temperature strength at 1800℃ 3KFr
, /mn#) and a copper tube 2 with a smaller diameter (linear expansion coefficient 1 /1.5
Insert the copper pipe 2 into the insertion part, and insert E31 into the inside of the copper pipe 2 at the insertion part.
1R304 (Linear expansion coefficient IF & 7 x 10-'/
'C, high temperature strength at 800℃ 28KF17mm
The outer pressure of the iron pipe 1 at the insertion part is -'' Kel alloy (composition Ni-lMo-5Fe) (
Linear expansion coefficient If, '501F! 7mn? ) A more constraint η17 is placed.

Although this arrangement example is just one example, as mentioned above, the core 6 corresponds to the joining temperature determined by the material combination of the tube 1.2, and the core 6 has a coefficient of linear expansion larger than that of the material of the tube 1.2. The lever with high temperature strength is selected, and the outer restraint ring 7i is selected.
- A material having a coefficient of linear expansion equal to or smaller than the monthly yield of the tubes 1 and 2 and having high high temperature strength is selected.

When the above combination is heated to high temperature, S
Since the radial expansion of the US 304 core 6 is larger than the inner diameter expansion of the copper tube 2, the radial expansion of the cut nickel alloy restraint ring 7 is smaller than the inner diameter expansion of the iron tube 1. A compressive force is applied between the and copper tube 2, and this
Diffusion bonding 8 between the steel W1 and the copper pipe 2 is completed.

At the time of this diffusion bonding, if F-shaping is applied between the core 6 and the copper tube 2 and between the restraining ring 7 and the iron tube 1, the core 6 and The restraint ring 7#'i can be easily removed.

The magnitude of the compressive force in the present invention is determined by the combination of heating temperature and materials, so the combination of K and materials should be determined so that a predetermined force is produced at the required temperature during bonding. Once again, the necessary sales items are as follows.

Coefficient of linear expansion of material Core > Constraint ring High temperature strength at bonding temperature Core = Constraint ring ≧ Pipe 1.2 The coefficient of linear expansion of the tube 1 and the tube 2 with a smaller diameter than that is that the latter is larger. Although advantageous, the present invention does not require this to be the case.

The present invention has an industrial effect in that when a large number of pipes are to be joined at the same time, the work can be easily carried out because no pressure equipment is required.

[Brief explanation of the drawing]

1 and 2 show a conventional method of joining pipes by brazing numbers, and m3tl';4 shows one embodiment of the present invention. ■-Ito 7 -47

Claims (1)

[Claims] A second tube with a smaller diameter is inserted into the first tube, and the first tube is attached to the outer surface of the first tube in the insertion portion. It has higher high-temperature strength than the No. 2 tube, and the coefficient of linear expansion is the first. A restraining ring made of a material that is equal to or smaller than the second pipe is placed inside the second pipe of the fitting part, and has a high temperature strength greater than that of the RFL 2 pipe, and is made of a material with ml, F, 2 A diffusion bonding method for tubular products, characterized by placing a core made of a material with a larger M expansion coefficient than the tube and heating it to a high temperature.