Nickel-titanium shape memory alloy composite pipe joint forming method

Abstract

The invention aims at providing a nickel-titanium shape memory alloy composite pipe joint forming method comprising the following steps of: assembling two layers of nickel-titanium shape memory pipes together in a way of clearance fit or interference fit to form a double-layer pipe, wherein the inner diameter d0 of the double-layer pipe is less than the outer diameter d2 of two pipes to be connected; performing expanding deformation on the double-layer pipe to enlarge the inner diameter of the double-layer pipe to d1 so as to compound and form the two layers of nickel-titanium shape memory pipes into a whole, wherein the d1 is more than the outer diameter d2 of the pipes to be connected; sheathing a pipe joint with the expanded diameter outside the two pipes to be connected; and recovering the shape of the pipe joint through low-temperature heating, and connecting the two pipes after the pipe joint is automatically contracted, thereby completing the forming of the pipe joint. The nickel-titanium shape memory alloy composite pipe joint forming method overcomes the defect that the wall of the conventional nickel-titanium shape memory alloy pipe joint is excessively thin or thick, and ensures the nickel-titanium shape memory alloy pipe joint to have enough fastening force and enough strength so as to enable the nickel-titanium shape memory alloy pipe joint to have excellent connection performance.

Description

technical field [0001] The invention relates to a pipe joint forming method, in particular to a pipe joint forming method in the technical field of precision manufacturing of pipe joint parts. Background technique [0002] Nickel-titanium shape memory alloys have been widely used in engineering fields because of their good shape memory effect and superelasticity. The shape memory effect of shape memory alloy refers to plastic deformation in a certain low temperature phase, and then heated to a certain temperature, the material undergoes a phase change and can return to the state before plastic deformation. The most typical application of nickel-titanium shape memory alloy in shape memory effect is shape memory alloy pipe joint. Nickel-titanium shape memory alloy pipe joints can realize the connection of two pipes, which is different from threaded mechanical connection and welding. In the application of nickel-titanium shape memory alloy pipe joints, the pipe joint whose in...

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Problems solved by technology

In particular, the wall thickness of the nickel-titanium shape memory alloy pipe joint is very important to the connection performance of the pipe joint. If the wall thickness is too thin, the strength of the pipe joint is insufficient, and the fastening force cannot meet the use requirements. During the expansion process of the joint, there is a gradient deformation problem, that is, the inner metal has a large deformation, while the outer metal has a small deformation, which will affect the subsequent shape recovery of the nickel-titanium shape memory alloy pipe joint, resulting in fastening Therefore, optimizing the wall thickness of nickel-titanium shape memory alloy pipe joints has always been a research topic in the engineering field.

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