Radial stretching expanding pipe for expanding shape memory alloy pipe joint

Abstract

The invention relates to an expanding tool for a shape memory alloy pipe joint, in particular to a radial stretching expanding pipe for expanding the shape memory alloy pipe joint. The radial stretching expanding pipe is characterized in that a plurality of left-opening through slots and right-opening through slots are respectively formed in the wall body of a pipe body along the opening directions of two ends to divide the wall body of the pipe body into a plurality of elastic sheets. The radial stretching expanding pipe which is designed by the invention can be used for expanding the shape memory alloy pipe joint and has a large radial stretching amplitude and uniform integral expanding. Compared with the prior art, the radial stretching expanding pipe which is used as an expanding tool can increase the connecting strength and axial symmetry of the shape memory alloy pipe joint, avoids permanent residual deformation, and ensures the overall performance. Meanwhile, the expanding size of the shape memory alloy pipe joint is easily controlled, and the radial stretching expanding pipe can be used for expanding small-bore shape memory alloy pipe joints.

Description

technical field [0001] The invention relates to a diameter-expanding tool for a shape-memory alloy pipe joint, in particular to a radial telescopic expansion pipe for expanding the diameter of a shape-memory alloy pipe joint. Background technique [0002] Shape memory alloys are smart materials that can remember their original shape. The most typical application of the shape memory effect is the shape memory alloy pipe joint. [0003] Shape memory alloy pipe joints can realize the connection of two pipes, which is different from threaded mechanical connection and welding. The shape memory alloy pipe joint is a simple cylinder, which is machined in the parent phase state, its inner diameter is slightly smaller than the outer diameter of the connected piece, and the inner diameter is machined with ridges. During application, the shape memory alloy pipe joint is cooled to the martensitic state, and the diameter of the pipe joint is expanded by mechanical force, so that the in...

AI Technical Summary

Problems solved by technology

However, at present, the diameter expansion of the shape memory alloy pipe joint is realized by passing the rigid tapered punch through the pipe. Since the tapered punch passes through the pipe joint, it is in partial contact with the inner wall of the pipe joint. Therefore, the overall deformation of the pipe joint does not occur during the diameter expansion process, so there will be a large residual stress inside the pipe joint produced by this process

These residual stresses will not only affect the dimensional accuracy of the pipe joint, but may even continue to exist during the shape recovery process after assembly, affecting the connection performance, and will reduce the stress corrosion resistance of the pipe joint, thus reducing its service life

In addition, when the tapered punch is used to mechanically expand the shape memory pipe joint, it often causes local plastic deformation or scratches on the inner surface of the pipe joint, which will affect the shape memory effect and fastening force of the shape memory alloy pipe joint.

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