JPH0156855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a shape memory alloy coil spring having a pitch using a shape memory alloy wire and a core metal in which a helical groove is formed.

``Prior Art'' Shape memory alloy wire can be used as a special spring material that takes advantage of its property that its 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.

``Problems to be solved by the invention'' However, shape memory alloy wire rods are extremely 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 coil spring with a pitch using a shape memory alloy because it is necessary to somehow constrain the shape memory alloy material to the desired shape during heat treatment.

``Means for Solving the Problems'' The present invention overcomes the above-mentioned manufacturing difficulties and provides a shape memory alloy coil spring that can integrally manufacture a shape memory alloy coil spring having a pitch with excellent precision and cycle dependence. This provides a method for manufacturing a coil spring, the gist of which is to wrap a shape memory alloy wire material around a core bar in which a spiral groove is formed, along the spiral groove, and to attach a fixing jig to both ends of the wire. and fix it. 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 gas or liquid. be.

``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 according to the required spring characteristics. SMA wire diameter,
The coil diameter, number of turns, free height, winding direction, etc. are determined by the intended use of the spring.

According to the spring shape determined in this manner, a metal core 2 is prepared in which a spiral groove 1 as shown in FIG. 1 is formed. In Figures 1 to 5, cases in which the winding direction is to the right have been illustrated and explained in detail, but in the case of a left-hand winding direction, the above-mentioned right-hand winding direction can be reversed, so the illustrations are not used. 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 Coil it in a spiral shape. and
The terminal end 6 of the SMA wire 4 is connected to the core bar 2 as shown in Fig. 3.
It is fixed via a second wire fixing jig 7 provided at the other end. This makes it brittle and difficult to plastically work.
The SMA wire 4 can be accurately wound around the core metal 2, and the hook portion, which has been considered difficult, can also be manufactured integrally.

Next, I wrapped it around the core metal 2 mentioned above and fixed both ends.
The SMA wire 4 is subjected to shape memory heat treatment at a constant temperature and time. Through this heat treatment, SMA wire 4
memorizes the shape along the helical groove 1 formed in the core metal 2.

Furthermore, the core metal 2 was subjected to memory treatment by heat treatment.
The SMA wire 4 that has been wound and fixed is left as it is in a gas or liquid to cool it.

After cooling sufficiently in this way, the first
Then, remove the second wire fixing jigs 3 and 7, and remove the helical SMA wire 4 from the core bar 2.
This removed SMA wire rod 4 has a shape as shown in Fig. 4, and the portions 8 and 9 held by the first and second wire rod fixing jigs 3 and 7 at both ends are attached to tension coil springs. It can be used as is as a hook part. Further, by cutting and removing both ends at points A and B in FIG. 4, a compression coil spring shown in FIG. 5 can be obtained.

``Effects of the Invention'' As detailed above, in the present invention, a shape memory alloy coil spring is manufactured integrally and through heat treatment, so a shape memory alloy coil spring with a hook part, which was considered difficult in the past, can be produced. The present invention has the effect of being able to manufacture the shape memory alloy coil springs in one piece without any troublesome labor and time, and also allows the shape memory alloy coil springs to be manufactured in one piece having pitches with excellent precision and cycle dependence. It is also presumed that this increases the critical stress for slippage, improves cycle dependence, and provides 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 drawings]

The drawings show one embodiment of the present invention. 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. 3 is a front view of the core metal.
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. 1... spiral groove, 2... core metal, 3... first wire fixing jig, 4... SMA wire rod, 5... starting end,
6... Termination, 7... Second wire fixing jig, 8, 9
……part.

Claims (1)

[Claims] 1. A shape memory alloy wire is wound around a core bar in which a spiral groove is formed, along the spiral groove, and both ends of the wire 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 gas or liquid. A method for manufacturing a shape memory alloy tension and compression coil spring.