JPS6059054A - Thermal response element - Google Patents

Abstract

PURPOSE:To obtain a thermal response element having a high coefft. of curvature by forming an element from a shape memory alloy having partially different transformation temps. and by applying a strain to the element beforehand. CONSTITUTION:A thermal response element is formed from a shape memory alloy having partially different transformation temps. such as a Ti-Ni alloy or a Cu-Zn-Al alloy. The element may be formed by bonding plural kinds of such shape memory alloys together. A strain is applied to the element beforehand by carrying out bending or other working at a temp. above or below each transformation temp. When the temp. of the element is raised or dropped, each segment of the element produces the shape memory effect in succession as it attains to the transformation temp., so deformation corresponding to the quantity of the strain applied beforehand is caused to the alloy or vanished. The thermal response element is suitable for use as a temp. sensitive element or an actuator for space machinery or a robot.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a highly sensitive thermally responsive element that has high operability against temperature changes.

[Technical background of the invention and its problems]

Generally, bimetals are often used as thermally responsive elements because they have a simple structure and are inexpensive. Bimetal has a structure in which two or more types of metal plates with different coefficients of thermal expansion are pressed together, and utilizes the effect of forming a dowel shape in proportion to temperature changes. Therefore, the performance as a bimetal - curvature coefficient (curvature of temperature curve) is determined by the difference in thermal expansion of the metal materials used. The most highly sensitive bimetal currently in use is one classified by JIS TMI, and is a bimetal with a curvature coefficient of 19.6 Cxlo/''O) composed of amber on the low expansion side and a manganese alloy on the high expansion side.

However, in recent years, actuators and temperature-sensing elements for robots, artificial rust stars, etc. are required to be lightweight, and if they have the same operational performance, they can be made smaller. A seaweed-sensitive thermoresponsive element has been desired.

On the other hand, there are highly sensitive thermally responsive elements that utilize the shape memory effect of alloys such as Nitinol, which is made of Nr-Ti alloys, but this is due to the transformation phenomenon of the alloy. It only responds around the transformation temperature, and unlike bimetals, it was not possible to generate an operating force proportional to temperature changes within a certain temperature range.

[Purpose of the invention]

The present invention overcomes the drawbacks of the prior art and provides a highly sensitive thermally responsive element suitable for temperature sensing elements and actuators for space equipment and robots.

C. Summary of the Invention] The highly sensitive thermally responsive element of the present invention is constructed of shape memory alloys having partially different transformation temperatures, or is constructed by joining a plurality of shape memory alloys having different transformation temperatures, and is constructed of shape memory alloys having partially different transformation temperatures. Or, it is characterized by being pre-strained at low temperature.

〔Effect of the invention〕

The thermally responsive element of the present invention is partially composed of shape memory alloys having different transformation temperatures, or is composed of a plurality of shape memory alloys having different transformation temperatures joined together, and is made at a temperature higher or lower than each transformation temperature. By applying strain in advance, when the temperature is raised or lowered, the shape memory effect will appear in each divided part as it reaches the transformation temperature, resulting in the alloy as a whole deforming corresponding to the amount of strain given in advance. It is characterized by the ability to appear or disappear.

The shape memory alloy constituting the present invention is Ag-Cd alloy, Au
-Cd alloy, 0u7AA-Nf gold alloy 0u-Au-Zn
Alloy, 0u-8u alloy, 0u-Zn alloy, 0u-Zn-
X (X=S i , an .

A4. Ga) alloy, In-TA! Alloy, N1-A1
Alloy, Ti-Ni alloy, Fe-Pt alloy, Fe-Pd
alloys, and Mn-0u alloys.

In these alloy systems, each can be made by sintering metal powders with partially varied compositions, or by subjecting an alloy body of uniform composition to partially different heat treatments or cold working with different processing rates. Shape memory alloys with different transformation temperatures can be obtained.

Furthermore, the shape memory alloy can also be obtained by performing a diffusion treatment on alloying elements while partially holding the alloy at different temperatures, or by using methods such as ion implantation.

Also, if the temperature range that requires the desired thermal response is large,
In order to prevent unnaturalness from occurring in the temperature change #1 line of the thermally responsive element, it is desirable to increase the number of shape memory alloys having different transformation temperatures and increase the number of divisions. Furthermore, when joining multiple shape memory alloys, normal arc welding may be used, but since the transformation temperature of shape memory alloys depends on the content of the constituent elements, electron beam welding, laser welding, resistance welding, etc. Bonding methods with small melt widths such as welding, solid phase and liquid phase diffusion welding are desirable.

Example 1 Atomic Ti-50%Ni, Ti-50°25%Ni
, Ti-50,5%Ni, Ti-50,75%Ni
, Ti-51%Ni alloy powder was prepared, and 2511I
Fill it in layers in the axial direction into a cylindrical mold with a diameter of II.
Pressing treatment of TOn/α2 was performed.

Next, a sintering process was performed at 900° C. for 3 hours in a vacuum furnace at 10·ttrmHg to obtain a composite cylinder.

A plate-like TP with a thickness of 1 mm, a width of 10 mm, and a length of 50+ m is cut out from this cylinder, and after annealing at 700°C, R = 400°C.
= 25 mm bending process was performed. This TP is 176
Return it to a straight line at ℃ and support it with a cantilever method (operating length 45 mm)
When the displacement of the free end was measured, it was 4 Qmm at 100°C. The time coefficient of the thermally responsive element is 112.2
10/”O.

Example 2 Atomic 0u-13, 5%Zn-8%Al, 0u-1
5,25%Zn-7,56%)J, 0u-17%Z
n-7,13'161'JJ, 0u-18,75%Z
n-6,69%) J, 0u-20,5% Zn-6
,25%! 'J alloys were each melted in a high-frequency melting furnace. From these alloys, the thickness is 3, the width is 15, and the width is 20.
A flat plate with a length of
A composite cylinder with a width of 15 fiils and a length of 100 mm was obtained.

This composite flat plate has a thickness of 1um and a width of 1olI+! , length 1
A test piece of 00 silk was cut out and annealed at 500"0. This test piece was bent at 15°C for a distance of 50111 m, supported in a cantilever manner (working length 90 II), and the displacement of the free end was measured. As a result, the temperature was 80 inches at 125°C.

The momentary coefficient of this thermally responsive element is 79. o X 10-'
/-C! Met.

As described above in the embodiments, the present invention provides a thermally responsive element which is constructed of shape memory alloys having partially different transformation temperatures and has a very large momentary coefficient when strain is applied in advance. However, its industrial value is great.

Claims (1)

[Scope of Claims] '(1) A thermal response characterized in that it is composed of shape memory alloys having partially different transformation temperatures and is strained in advance at a temperature higher or lower than each transformation temperature. element. (2) Shape memory alloys with different transformation temperatures