JP2002105566A - Coil spring having shape memory effect and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil spring having shape memory effect reversible in a radial direction with respect to a temperature cycle such that a spontaneous shape when heated is elongated in the radial direction, and a spontaneous shape when cooled is shrinked in the radial direction. SOLUTION: A wire rod obtained by subjecting a TiNi based alloy having a main composition containing Ni in the range of 50.3 to 53.0 atomic %, and the balance Ti to the treatment of hot working and cold working is wound around a columnar first bar-shaped member 11 so as to tightly be adhered and is subjected to the heat treatment of single phase transforming treatment to obtain a coil spring of a TiNi single phase, and, thereafter, the coil spring is wound around a second bar-shaped member having a radius larger than that of the columnar bar-shaped member so as to tightly be adhered, is formed and is subjected to aging treatment to form a coil spring having shape memory effect in which, spontaneously, the shape changes so as to be elongated in the radius direction when heated, and be shrinked in the radius direction when cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coil spring using a TiNi-based alloy having a shape memory effect, and more particularly, to a coil spring having a reversible shape memory effect in a radial direction and a method for manufacturing the same.

[0002]

2. Description of the Related Art It is known that a TiNi-based alloy exhibits a remarkable shape memory effect accompanying a reverse transformation of a thermoelastic martensitic transformation. In general, most alloys that exhibit a shape memory effect have reversible shape memory effects,
It is said to exhibit a superelastic effect. In particular, since the reversible shape memory effect spontaneously changes its outer shape with respect to a temperature cycle extending above and below the transformation point, its application range is larger than that of a transient shape change.

As a method for imparting a reversible shape memory effect to a spring using a TiNi-based shape memory alloy, after a single-phase treatment,
There is a method of performing aging treatment under constraint. This is because a wire made of a TiNi-based alloy having a specific composition is helically wound around a rod-shaped member, subjected to a single-phase treatment, and then subjected to an aging treatment by restricting to a different pitch. It is a method of manufacturing.

[0004]

In the above-mentioned manufacturing method, there is a problem that the shape memory effect is exhibited only in the longitudinal direction of the spring. Accordingly, an object of the present invention is to provide a spontaneous shape that elongates in the radial direction when heated and a spontaneous shape that shrinks in the radial direction when cooling, and that is reversibly radially reversible to temperature cycles. An object of the present invention is to provide a coil spring having a shape memory effect and a method for manufacturing the same.

[0005]

The alloy provided by the present invention has a main composition of 50.3 atomic percent or more of Ni to 5 to 5 atomic percent.
A TiNi-based alloy comprising the balance of Ti in a range of 3.0 atomic percent or less, having a multiphase structure of a martensite phase of a NiTi intermetallic compound and a Ni-excess precipitation phase, and a reversible shape memory effect. Is a TiNi-based alloy having

According to the method for manufacturing a coil spring having a shape memory effect in the radial direction according to the present invention, a TiNi-based alloy having a main composition in a range of 50.3 atomic% or more to 53.0 atomic% or less and a balance of Ti is used. After melting and processing to obtain a wire or a strip, the coil is wound around a rod-shaped member at a pitch interval of close contact, and subjected to a heat treatment of a single-phase treatment at 600 ° C. or more to obtain a coil spring with a pitch close contact.

After that, the coil is wound around a rod-shaped member having a large radius in a state in which the pitch is closely contacted, and is subjected to an aging treatment at a temperature of 600 ° C. or less. A coil spring having a two-way shape memory effect that is reversible radially in a cycle can be provided.

That is, according to the present invention, the main composition is Ni50.3.
A wire rod obtained by subjecting a TiNi-based alloy consisting of the balance of Ti to a process such as hot working or cold working in the range of not less than atomic percent to not more than 53.0 atomic percent is converted into a cylindrical first rod-shaped member. And a heat treatment of a single-phase treatment is performed to obtain a single-phase TiNi coil spring. Thereafter, the coil spring is wound tightly on a second rod-shaped member having a larger radius than the cylindrical rod-shaped member. A coil spring having a shape memory effect, which is formed and subjected to aging treatment, and has a shape memory effect in which the shape at the time of heating elongates spontaneously in the radial direction and the shape at the time of cooling shrinks and changes in the radial direction.

In the present invention, the main composition is Ni50.3.
A wire obtained by subjecting a TiNi-based alloy having a balance of Ti to a hot working, a cold working, or the like, in a range of not less than 5 atomic% to not more than 53.0 atomic%, is formed into a first cylindrical rod. The coil spring is wound in close contact with the member and subjected to a heat treatment of a single-phase treatment to obtain a single-phase TiNi coil spring. Thereafter, the coil spring is wound in close contact with a second rod member having a larger radius than the cylindrical rod member. Is a method of manufacturing a coil spring having a shape memory effect in which the shape at the time of heating is spontaneously elongated in the radial direction and the shape at the time of cooling is shrunk and changed in the radial direction by spontaneously performing aging treatment.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coil spring having a shape memory effect according to an embodiment of the present invention and a method for manufacturing the same will be described below.

A coil spring having a shape memory effect according to an embodiment of the present invention has a main composition of 51.0 atomic percent of Ni,
A TiNi-based alloy consisting of the remaining Ti was subjected to a process such as hot working or cold working to obtain a wire rod processed to φ1.0 mm.

As shown in FIG. 1, a wire rod of an NiTi alloy is wound around a first rod-shaped member 11 having a diameter of 8 mm so that the pitch interval is in close contact with each other, and a coil spring 10 is formed. Fix the end of the wire, 7
The TiNi single phase treatment was performed at 00 ° C. for 1 hour. Book Ti
In general, the condition of the Ni single-phase treatment is selected from the range of conditions used in the single-phase treatment of the shape memory alloy. In this example, 700 ° C. for one hour was selected.

Next, as shown in FIG. 2, the coil spring 10 of FIG.
The coil spring 12 is wound around the rod-shaped member 13 so that the pitch interval is in close contact, and the end of the wire is fixed.
The aging treatment was performed at 0 ° C. for 48 hours. As for the aging treatment, a range of conditions used in the aging treatment of the shape memory alloy is generally selected.
C., 48 hours.

Thereafter, the coil spring A is removed from the rod-shaped member at room temperature, and when heated and cooled, as shown in FIG. 3, shows the shape of the coil spring A contracted in the radial direction at 30 ° C. as shown in FIG. 3, and at 60 ° C. as shown in FIG. The shape of the coil spring B extending in the radial direction is shown.

That is, as shown in FIG. 3, in the heat treatment,
The spring extended in the radial direction, and in the cooling process, the spring contracted in the radial direction.

As described above, by making the constraint diameter at the time of aging treatment larger than the constraint diameter at the time of single-phase treatment, it was possible to determine a shape that expands in the radial direction during heating and contracts in the radial direction during cooling. The main composition of the TiNi-based alloy used for the coil spring having the shape memory effect according to the embodiment of the present invention is Ni5
The balance Ti is selected in a range from 0.3 atomic percent to 53.0 atomic percent. This is Ni5
If the amount is less than 0.3 atomic percent, a sufficient reversible shape memory effect is not obtained even if the subsequent heat treatment is performed. If the amount is more than 53.0 atomic percent, the subsequent heat treatment is similarly performed. This is because a sufficient reversible shape memory effect is not performed even if it is performed.

Although the spring reversibly expands and contracts between 30 ° C. and 60 ° C. in the embodiment, the temperature range showing the reversibility can be set arbitrarily by selecting the Ni concentration and the constraint aging conditions. .

[0018]

According to the present invention, when heated, it expands in the radial direction,
It has become possible to provide a coil spring having a bidirectional shape memory effect that is reversible in the radial direction in a temperature cycle in which the shape becomes radially contracted upon cooling. This has made it possible to apply shape memory alloys to temperature sensors, actuators, and the like.

[Brief description of the drawings]

FIG. 1 shows a single phase treatment at 600 ° C. or higher according to the present invention.
Explanatory drawing which shows the state which wound Ni-type alloy wire tightly around the rod-shaped member.

FIG. 2 shows that TiN is used during the aging treatment at 600 ° C. or less according to the present invention.
Explanatory drawing which shows the situation which wound the i-type alloy wire on the stick-shaped member thicker than FIG.

FIG. 3 is an explanatory diagram showing a change in the shape of a coil during heating and cooling after heat treatment in the shapes of FIGS. 1 and 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Coil spring (at the time of a single phase process) 11 1st rod-shaped member 12 Coil spring (at the time of aging treatment) 13 2nd rod-shaped member A Coil spring contracted in the radial direction B Coil spring expanded in the radial direction

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C22F 1/00 670 C22F 1/00 670 682 682 683 683 683 685 685Z C22K 1:00 C22K 1:00

Claims (2)

[Claims] 1. The composition according to claim 1, wherein the main composition is in the range of not less than 50.3 atomic percent to 53.0 atomic percent of Ni, and
A wire obtained by subjecting a TiNi-based alloy made of i to hot working and cold working is wound so as to be in close contact with a cylindrical first rod-shaped member and subjected to a heat treatment of a single-phase treatment, T
An iNi single-phase coil spring is obtained, and then wound around the second rod-shaped member having a larger radius than the columnar rod-shaped member to form a coil spring and subjected to aging treatment. A coil spring having a shape memory effect, wherein the shape of the coil spring expands in the radial direction and the shape upon cooling shrinks and changes in the radial direction. 2. A TiNi-based alloy having a main composition in a range of not less than 50.3 atomic percent to 53.0 atomic percent of Ni and the balance being Ti, obtained by hot working and cold working. The wound wire is wound around a cylindrical first rod-shaped member so as to be in close contact therewith and subjected to a heat treatment of a single-phase treatment, so that T
An iNi single-phase coil spring is formed. Thereafter, the coil spring is wound in close contact with a second rod-shaped member having a larger radius than the columnar rod-shaped member, and the coil spring is formed and subjected to an aging treatment. A method for manufacturing a coil spring having a shape memory effect, characterized in that the shape expands in the radial direction and the shape upon cooling shrinks and changes in the radial direction.