JPH046788B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of winding a heater for heating a drive element around a drive element using a shape memory alloy.

Shape memory alloys utilize the phenomenon that occurs when the low-temperature phase generated by thermoelastic martensitic transformation is deformed and then reversely transformed into the high-temperature phase by heating. It changes to an austenite structure at higher temperatures, and changes to a martensitic structure at lower temperatures. When this shape memory alloy is cooled from the high temperature side, the austenitic structure transforms to the martensitic structure, and it has superelasticity.On the other hand, when it is heated from the low temperature side, the martensitic structure transforms to the austenite structure, and the forming process It returns to the memorized shape. Nickel-titanium, copper-aluminum-nickel, copper-aluminum, etc. are known as alloys that exhibit such a shape memory effect, and when these shape memory alloys are used as a drive element as a drive source, heating from the outside, It utilized the displacement of the shape memory alloy as it cooled. As a means for heating a shape memory alloy, a method generally known is to wrap a heater around a drive element made of a shape memory alloy to heat the drive element, as shown in Japanese Patent Application Laid-Open No. 57-25572. It is being However, the work of winding the heater around the drive element is extremely difficult, especially if the drive element is coiled or has a complicated bent shape, resulting in poor workability and manufacturing. This increased costs and led to higher product costs. Additionally, the heater must be wound evenly around the driving element; if the heater is not wound evenly, the heating characteristics of the driving element will deteriorate.
Uniform operation and desired operation cannot be obtained. Conventional heaters have disadvantages in that the heater cannot be evenly wound around a drive element having a complicated shape, such as a coil, and that the heater cannot be easily wound. The method of winding a heater for a drive element made of a shape memory alloy according to the present invention has been devised in view of the above points, and its purpose is to extremely easily and reliably wind the heater around a wire. shall be.

Next, a method of winding a heater for a drive element made of a shape memory alloy according to the present invention will be explained.

As shown in FIG. 1, numeral 1 is a wire forming a driving element, which is made of a shape memory alloy material such as nickel or titanium and formed into a substantially linear shape of a desired length. There is no limitation, and a band material may also be used.

Next, as shown in FIG. 2, the wire 1 is formed into a desired shape such as a coil shape, and for example,
Heat treatment is performed at a high temperature of around 400℃ for shape memory.

Next, at the martensitic phase temperature where the composition of the shape memory alloy is in the aartensitic phase (specifically, at a temperature below the martensitic transformation start point (As point)), it is again stretched into a substantially linear shape as shown in FIG.
Next, as shown in FIG. 4, the strand 1 in a substantially straight state
A heater 2 such as a nichrome wire is wound around the . With the above, a driving element around which the heater 2 was wound could be formed.

When the heater 2 is energized in this state, the heater 2 self-generates heat, and this heat generation warms the strand 1 and increases the temperature of the strand 1, bringing the temperature of the strand 1 to the reverse transformation starting point (As point). When this happens, it changes into the shape memorized by the heat treatment process, that is, into a coil shape.

As described above, according to the present invention, the first step is to form a material made of a shape memory alloy into a substantially straight line to form a wire of a desired length, and to form the wire into a predetermined shape.
a heat treatment step to memorize the shape; a second step of stretching the wire into a substantially straight line again at the martensitic phase temperature; a third step of winding a heater around the wire that was in a straight state in the second step; A heater is wound around the outer periphery of a drive element made of a shape memory alloy.

Since the winding of the coil around the wire was carried out after the wire had been stretched into a substantially straight line at the martensitic phase temperature, the wire had no relation to the shape memorized in the shape memory alloy, and the wire was stretched into a straight line at the martensitic phase temperature. Since the process involved winding the wire, the heater could be wound reliably and easily around the wire, making it easier to manufacture and significantly reducing manufacturing costs. .

[Brief explanation of drawings]

The figures show a method of winding a heater for a drive element made of a shape memory alloy according to the present invention, and FIG. 1 shows the first step of forming a wire of a desired length, and FIG. Figure 3 shows the heat treatment step of forming the wire into a shape and memorizing the shape. Figure 3 shows the second step of stretching the wire in a substantially straight line at the martensitic phase temperature. Figure 4 shows the second step of winding the wire around the heater. This shows three steps. 1... Bare wire, 2... Heater.

Claims (1)

[Claims] 1. A first step of forming an element made of a shape memory alloy into a wire of a desired length, a heat treatment step of forming it into a predetermined shape and memorizing the shape, and a step of stretching the element into a substantially straight line at a martensitic phase temperature. A method for winding a heater in a drive element made of a shape memory alloy, comprising: two steps, and a third step of winding a heater around the substantially straight wire.