JPS60172715A - Pipe connection method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of connecting pipes using a shape memory alloy pipe joint.

Conventional configurations and their problems As an alternative to the conventional brazing and flaring methods as a pipe connection method for air conditioning equipment and hot water supply equipment piping,
There are three methods: adhesive method and shape memory alloy pipe joint method.

The adhesive method is as shown in the cross-sectional view in Figure 1.
A thermosetting resin 3 such as epoxy resin is applied to at least one joint surface of the tube 2 and the other tube 2, the tube 2 is inserted into the expanded inner surface of the tube 1, and then heated to form the thermosetting resin a. This is a method of hardening and connecting.

Although this method is low in cost and has good workability, it is weak in strength because the epoxy resin takes care of the connection strength, and the viscosity of the epoxy resin decreases just before it hardens, causing the epoxy resin to flow and become localized, creating cavities. There was a problem in that it was easy to form.

In the shape memory alloy pipe joint method, as shown in the cross-sectional view in Fig. 2, the pipes 1.2 on both sides are inserted into the shape memory alloy joint 4, and then the shape memory alloy joint is heated with a torch or the like. Then, the shape memory alloy ring 41 contracts, and the contraction force tightens and contracts the liner 42, causing the liner 42 or the tube 1.
2 is tightened, and at that time, the epoxy resin 43 applied to the inside of the liner 42 is softened and then hardened to form a connection.

This method uses the strong tightening force of the shape memory alloy ring 41 and the airtightness maintaining effect of the epoxy resin 43.
Although it is excellent in terms of strength and airtightness, it has the following problems. There was a problem in that the cost was high due to the configuration of the shape memory alloy ring, liner, and epoxy resin.

In particular, in recent years, shape memory alloy joints have attracted attention because they are easier to work with than brazing or flaring methods, and can maintain strength and airtightness, and there is a desire to reduce costs.

OBJECTS OF THE INVENTION The present invention is intended to solve these problems, and aims to provide a pipe connection that has good strength and airtightness and is inexpensive.

Structure of the Invention In order to achieve this object, the connection part of the pipes to be connected is configured such that the other pipe is fit into the inside of one pipe, and the inner surface of the connection part of one pipe and the connection part of the other pipe are A thermosetting resin is applied to at least one of the outer surfaces, one tube is inserted into the other tube, a shape memory alloy ring is fitted around the outer periphery of the joint, and then the shape memory alloy ring is heated and shrunk. It provides a complete method for connecting pipes that completely cures thermosetting resin.

Since one of the connecting pipes is used as a liner, only a shape memory alloy ring is sufficient for the shape memory alloy joint.
Therefore, it is inexpensive, and furthermore, it is possible to maintain high strength due to the tightening force of the shape memory alloy ring and airtightness due to the thermosetting resin.

DESCRIPTION OF EMBODIMENTS The present invention will be described below with reference to FIG. The configuration allows clearance fit. In the embodiment, the connecting portion 5 of one of the tubes 1 was expanded to have this configuration. The maximum gap for this clearance fit is within 3% of the outer diameter of the tube 2. This is done by applying a thin layer of epoxy resin evenly to the outer periphery of the connecting portion of the tube 2 according to the shape method.

After that, the tube 2 is inserted inside the connection part of the tube 1 as in the third za.

On the other hand, the shape memory alloy ring is made of a copper alloy, expands in liquid nitrogen, and has an inner diameter that is directly aligned with the outer periphery of the connecting portion of the pipe 1 to be connected. This shape memory alloy RISIG 7 is heated to a third temperature at room temperature.
Fit it into the connection part as shown.

Then, with a propane torch, shape memory alloy ring 7
When heated, this shape memory alloy shrinks and tightens the joint 5 of the tube 1 because it has a composition that shrinks at temperatures above approximately 200°C. The tightening (because the q force is large,
Eliminate the gap with pipe 2, allow the softened epoxy resin to flow out, fill the contact area between pipe 1 and pipe 2 with gold, and tighten against pipe 1 as well7.This completes the connection operation. be. In this embodiment, since tubes 1 and 2 have the same dimensions, one tube 1
Although the connecting portion of the pipe is expanded, if the dimensions are such that the pipe 2 can be pushed into the pipe 1, the pipe does not need to be expanded.

Alternatively, the shape memory alloy ring 7 may be made of an rf'iN i Ti alloy. The epoxy resin is selected to be one that hardens at about the shrinkage temperature of the entire shape memory α ring.

Effects of the Invention According to the connection method of the present invention, the length of the shape memory alloy ring can be made shorter than that of a shape memory alloy joint, resulting in a very inexpensive product. Furthermore, due to the tightening force of the shape memory alloy ring and the elimination of voids in the tube 1L tube 2, the strength is increased, and the epoxy resin fills the minute voids, resulting in excellent airtightness.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a pipe connecting portion showing a conventional connecting method, and FIGS. 3 a, b, and c are cross-sectional views of a pipe connecting portion for explaining the connecting method of the present invention. 1.2...Pipe, 3.43.6...Thermosetting oil, 4...Shape memory alloy joint, 41.7
・River...Shape A, αα gold ring, 5...Connection part.

Claims (1)

[Claims] The connection part of the pipes to be connected is structured so that the other pipe is fit into the inside of one pipe, and a thermosetting resin is applied to at least one of the inner surface of the connection part of one pipe and the outer surface of the connection part of the other pipe. A method for connecting tubes, in which one tube is then inserted into the other tube, a shape memory alloy ring is fitted around the outer periphery of the joint, and the shape memory alloy ring is then heated to a temperature higher than its contraction temperature.