Coupling methods and coupling device using shape memory alloy pipe fittings

摘要

PURPOSE: To make use of the performance of a shape memory alloy and obtain corrosion-resistance by composing a configuration memory alloy tube fitting so as to practice necessary physical processing, after completion of coupling process by a configuration memory alloy tube fitting so that plastic deformation may show on the surface of the configuration memory alloy tube fitting. ;CONSTITUTION: A shape memory alloy composing a tube fitting 1 is heated upon positioning the tube fitting to the connecting section of a pipe 2. When the temperature reaches a transition starting degree, shape recovery action starts and the inside diameter dimension of the tube fitting 1 trends to shrink until it reaches the transition completion temperature t₂. At this time, because the outside diameter R₂ of the pipe 2 is set larger than the inside diameter R₀ of the tube fitting 1 in its early stage, deformation of the tube fitting 1 to the shrinking direction is restrained, tensile stress generates in the circumferential direction, and the pipe 2 is connected to the tube fitting 1 by stress acting on the pipe 2 in the radius direction. Physical processing by means of shot or the like is applied to the outside circumference of the shape memory alloy composing the tube fitting 1 so that plastic deformation may show only on the outside circumferential part, and then relaxes stress only on this portion.;COPYRIGHT: (C)1996,JPO