JPS6216834A - Production of coil spring of shape memory alloy - Google Patents

Abstract

PURPOSE:To enable the integral production of the shape memory alloy coil spring having a pitch excellent in the accuracy and cycle dependency by fixing a shape memory alloy wire by winding it on the core metal forming a spiral groove and by cooling it with a heat treatment. CONSTITUTION:The top end of an SMA wire 4 is fixed to a core metal 2 with the first jig 3 for fixing wires provided at the top end of the metallic core metal 2 forming a spiral groove 1 and its coiling is performed in spiral shape by winding along the spiral groove 1 of the core metal 2. The terminal of the SMA wire 4 is then fixed via the second fig for fixing wires provided at the other end of the core metal 2. The wire 4 is subjected to a shape memory heat treatment at and for a certain temp. and time as it is in succession. The wire 4 fixed by winding to the memory treated core metal 2 is further cooled by leaving it in a gaseous body or in a liquid as it is. Thereafter the fixing jig is removed and the SMA wire 4 becoming in a spiral shape by the core metal 2 is taken off.

Description

Detailed Description of the Invention r Industrial Field of Application J The present invention relates to a method of manufacturing a shape memory alloy coil spring having a pitch using a shape memory alloy wire rod and a core metal in which a helical groove is formed.

rPrior Art Shape memory alloy wire rods can be used as special spring materials that take advantage of the property that their transverse elastic modulus changes significantly depending on temperature. In particular, coil springs tend to be used as coil springs because the amount of distortion can be reduced and the amount of change in shape can be set large.

fProblems to be solved by the inventionJ However, shape memory alloy wires are very difficult to plastically work before heat treatment to memorize their shape, and they also have the characteristic of being brittle. It requires great care and a high degree of skill. Furthermore, it is extremely difficult to integrally manufacture a pitched coil spring using a shape memory alloy because it is necessary to somehow constrain the shape 212 alloy material to the desired shape during heat treatment.

Means for Solving Problems J The present invention overcomes the above-mentioned problems of difficult manufacturing, and also provides a shape memory alloy coil spring that can integrally manufacture a shape memory alloy coil spring that can accommodate pitches with excellent accuracy and cycle dependence. This provides a method for manufacturing an alloy coil spring, the gist of which is to wrap a shape memory alloy wire around a core metal with a helical groove formed therein, and to wrap both ends of the wire with a fixing jig. The shape memory alloy wire wound around the core metal is subjected to zero-order heat treatment to memorize its shape, thereby integrally forming a coil spring, and then left to cool in gas or liquid. It is.

``Example'' An example of the present invention will be described below based on the drawings.A nickel-titanium or copper-based shape memory alloy wire (hereinafter referred to as SMA wire) is used as the material, and the SMA wire is adjusted according to the required spring characteristics. The diameter, coil diameter, number of turns, free height, winding direction, etc. are determined by the intended use of the spring.

In accordance with the spring shape determined in this way, a metal core bar 2 is prepared in which a helical groove l as shown in FIG. 1 is formed. In Figs. 1 to 5, the case where the winding direction is right is illustrated and explained in detail, but in the case of the left winding direction, it is sufficient to think in the opposite way to the above-mentioned right winding direction, so only one figure is shown. and detailed explanation will be omitted.

Next, as shown in FIG. 2, the starting end 5 of the SMA wire 4 is fixed to the core bar 2' using the first wire fixing jig 3 provided at both ends of the core bar 2, and the starting end 5 of the SMA wire 4 is fixed to the helical groove 1 of the core bar 2. Coil it in a spiral shape. A second wire fixing jig 7 is provided with the terminal end 6 of the SMA wire 4 at the other end of the core bar 2 as shown in FIG.
Fixed via. As a result, the SMA wire 4, which is brittle and difficult to plastically work, can be accurately wound around the core metal 2, and the hook portion, which has been considered difficult, can also be manufactured integrally.

Subsequently, the SMA wire 4, which was wound around the core metal 2 and fixed at both ends, was subjected to shape memory heat treatment at a constant temperature for 1 hour. Through this heat treatment, the SMA wire 4 memorizes the shape along the helical groove l formed in the core metal 2.

Further, the SMAIa material 4 wound and fixed around the core bar 2 which has been subjected to memory treatment by heat treatment is left as it is in gas or liquid to cool.

After sufficiently cooling in this way, the first and second
The wire fixing jig 31.7 is removed, and the helical SMA wire 4 is removed from the core bar 2.

This removed 5MA1 material 4 has a shape as shown in FIG.
The parts 8 and 9 that were held down can be used as they are as the hook parts of the tension coil spring. Also, point A in Figure 4,
By cutting and removing both ends at point B, a compression coil spring shown in FIG. 5 can be obtained.

Effects of the Invention As detailed above, in the present invention, the shape memory alloy fill spring is integrally manufactured by heat treatment, so it is possible to eliminate the troublesome shape memory alloy coil spring with the hook portion, which was considered difficult in the past. This has the effect of allowing the coil springs to be manufactured in one piece without much effort, and also enables the integral manufacture of shape memory alloy coil springs with pitches with excellent accuracy and cycle dependence.Also, the critical stress of slipping can be reduced. It is estimated that this increases the cycle dependence, thereby imparting stability against temperature cycles.

Furthermore, it is possible to manufacture a shape memory alloy coil spring that has high precision, high strength, durability, and stability without causing a decrease in material strength, strength variation, deformation, etc.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a front view of the core metal, FIG. 2 is a front view showing the state in which the SMA wire is wound around the core metal, and FIG. FIG. 4 is a front view of a tension coil spring manufactured according to the present invention, and FIG. 5 is a front view of a compression coil spring manufactured according to the present invention. 10. - Spiral groove 2. Core bar 3. .・First wire fixing jig 411...SMA wire 5.1
1-Starting end 6・Ending end 7・Second wire fixing device 8.9・Part 7゛'$1 Figure Figure 4 Figure S

Claims (1)

[Claims] A shape memory alloy wire is wound around a core metal having a spiral groove formed therein, and both ends thereof are fixed. Next, the shape memory alloy wire wound around the core metal is subjected to heat treatment to memorize its shape to integrally form a coil spring, and then left to cool in a gas or liquid. Method for manufacturing memory alloy tension and compression coil springs.