JP2002182162A - Method of manufacturing spectacles frame using ultraelastic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a spectacles frame using an ultraelastic material which is supple and gives excellent wearing feeling at the time of wearing spectacles and has a small residual bend. SOLUTION: When the spectacles frame is manufactured by subjecting the ultraelastic material of a Ni-Ti-Co ternally alloy system to cold working, to molding into a prescribed spectacles frame shape and then to a shape memorizable heat treatment in a state holding the molded shape, the shape memorizable heat treatment is executed at a temperature of 400 deg.C to 440 deg.C for >=15 minutes. When ultraelastic material of a Ni-Ti binary alloy system is used, the shape memorizable heat treatment is executed at a temperature of 510 deg.C to 540 deg.C for >=15 minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an eyeglass frame using a superelastic material, and more particularly to a method of manufacturing a spectacle frame characterized by technical means for improving superelastic characteristics.

[0002]

2. Description of the Related Art Conventionally, a Ni-Ti-Co ternary superelastic material or a Ni-Ti binary superelastic material has been used by utilizing its excellent superelasticity. It has been proposed to use it as a spectacle frame (whole frame or part thereof).

In the case of such a spectacle frame using a superelastic material, the flexibility of the spectacle frame is much better than that of a conventional spectacle frame, and the wearing feeling when wearing spectacles is good. However, spectacle frames using a superelastic material proposed in this type in the past have not always been satisfactory in terms of superelastic properties, and there is still room for improvement.

[0004]

SUMMARY OF THE INVENTION A method for manufacturing an eyeglass frame using a superelastic material according to the present invention has been devised to solve such a problem. According to the first aspect of the present invention, the Ni-Ti-Co ternary superelastic material is cold-worked, then molded into a predetermined eyeglass frame shape, and subjected to shape memory heat treatment while maintaining the molded shape. When manufacturing the eyeglass frame by performing the heat treatment, the shape memory heat treatment is performed at a temperature of 400 ° C. or more and a recrystallization temperature or less.

According to a second aspect, in the first aspect, the shape memory heat treatment is performed at a temperature of 400 ° C. or more and 440 ° C. or less.

According to a third aspect of the present invention, in any one of the first and second aspects, the superelastic material is expressed by weight% and Ni: 53.00 to 55.50.
%, Co: 0.5 to 3.0%, with the balance being substantially composed of Ti.

According to a fourth aspect of the present invention, after a Ni-Ti binary superelastic material is cold-worked, it is formed into a predetermined eyeglass frame shape, and a shape memory heat treatment is performed while maintaining the formed shape. When manufacturing an eyeglass frame, the shape memory heat treatment is performed at a temperature of 510 ° C. or more and a recrystallization temperature or less.

According to a fifth aspect, in the fourth aspect, the shape memory heat treatment is performed at a temperature of 510 ° C. or more and 540 ° C. or less.

According to a sixth aspect of the present invention, the superelastic material according to any one of the fourth and fifth aspects has a Ni content of 55.80 to 56.20 by weight%.
%, With the balance being substantially composed of Ti.

A seventh aspect of the present invention is characterized in that in any one of the first to sixth aspects, the shape memory heat treatment is performed for 15 minutes or more.

An eighth aspect of the present invention is characterized in that, in any one of the first to seventh aspects, the cold working is performed at a working rate of 10% or more.

[0012]

In general, in order to manufacture a spectacle frame using a superelastic material, the superelastic material is subjected to cold working such as rolling or drawing to sufficiently harden the work, and thereafter the spectacle frame is produced. After forming into a shape, fix it to that shape,
In this state, a shape memory heat treatment is performed to obtain an eyeglass frame.

[0013] Superelasticity is a phenomenon in which when deformed beyond the limit of elasticity, it returns to its original shape when a load is removed. This superelasticity is induced by stress when a force is applied at a temperature higher than the transformation point. It appears when the austenite matrix transforms into a martensite phase. At this time, the crystal structure changes mainly due to shear deformation.

If dislocations occur during the deformation, the superelastic properties deteriorate. In the cold working, work hardening is previously generated to prevent this. The superelastic characteristics of the spectacle frame using the superelastic material, specifically, its flexibility, residual strain after removing the force, and the like depend on the manufacturing conditions including the cold working.

Accordingly, the present inventor paid attention to shape memory heat treatment after cold working, and examined the effect of the shape memory heat treatment conditions on the superelastic properties of a Ni-Ti-Co ternary superelastic material. It has been found that by performing this under specific conditions, specifically, at a temperature of 400 ° C. or more and a recrystallization temperature or less, excellent superelastic properties can be imparted to the spectacle frame. The present invention has been made based on such knowledge.

In the present invention, in particular, the shape memory heat treatment is
It is more desirable to carry out at a temperature of not less than 440 ° C. (Claim 2).

Here, the ternary superelastic material of the present invention may have a composition consisting of 53.00 to 55.50% of Ni, 0.5 to 3.0% of Co, and substantially Ti in balance by weight. (Claim 3).

On the other hand, when manufacturing a spectacle frame using a Ni-Ti binary superelastic material, the shape memory heat treatment is preferably performed at a temperature of 510 ° C. or more and a recrystallization temperature or less (claim 4). When shape memory heat treatment is performed under the conditions, Ni-Ti
A superelastic property can be improved in an eyeglass frame using a binary superelastic material. In this case, it is more preferable to perform the shape memory heat treatment at a temperature of 510 ° C. or more and 540 ° C. or less (claim 5).

The binary superelastic material has a weight percentage of N
i: 55.80 to 56.20%, with the balance being substantially composed of Ti (claim 6). Further, when using any of these ternary and binary superelastic materials, it is desirable to perform the shape memory heat treatment over 15 minutes or more (claim 7). It is desirable that the cold working is performed at a working rate of 10% or more (claim 8).

[0020]

Next, embodiments of the present invention will be described in detail. FIG.
As the superelastic material applied to the spectacle frame 10 (however, the illustrated one is an example), a superelastic material having a chemical composition shown in Table 1 (No. 1 in the table is Ni-Ti-Co ternary system, No. .2 is Ni-Ti
(Binary system) was drawn to a diameter of φ1.2 mm by wire drawing, and subsequently cold-worked to wire drawing of φ1.0 mm. The processing rate (area reduction rate) at this time is 30%.

The recrystallization temperature of both No. 1 and No. 2 materials was 650 ° C. In FIG. 1, reference numeral 10a denotes a temple in the eyeglass frame 10, and 10b denotes a temple.
c is over and 10d is over.

Subsequently, a shape memory heat treatment was performed while maintaining the temperature shown in FIG. 3 for 60 minutes.

[0023]

[Table 1]

The suppleness and residual bending of the superelastic material required for the spectacle frame 10 were evaluated by the three-point bending test method shown in FIG. In this three-point bending test, sample 12 was
Is supported by P ₁ and P ₂ by a pair of support members 14 spaced 5 mm, and press the central portion downwardly measured load required to deflect 6 mm, it was evaluated supple the magnitude of the load. The residual bending after removing the load was also measured.

FIG. 3 shows the test results for No. 1 material, and FIG.
The test results for the No. 2 material are shown in FIG. As can be seen from the results in FIG. 3, the No. 1 material, namely, Ni-Ti-Co
For the ternary superelastic material, the bending load required for the 6 mm indentation is reduced when the shape memory heat treatment is performed at 400 ° C. or higher, and therefore, it is possible to impart a good flexibility to the spectacle frame 10. I understand. It is to be noted that the residual bending is most favorable in the range up to 440 ° C. because the residual bending is the least. Therefore, it is more preferable to perform the shape memory heat treatment at a temperature of 400 ° C. to 440 ° C. for the No. 1 material.

On the other hand, with regard to the No. 2 material, that is, the Ni-Ti binary superelastic material, good results were obtained when the shape memory heat treatment was performed at 510 ° C. or higher. Especially 510 ° C-540 ° C
When the shape memory heat treatment is performed in the above temperature range, the flexibility and the residual bending are both good, and therefore, the shape memory heat treatment is more desirably performed in this temperature range.

Next, a tensile test was performed on No. 1 and No. 2 materials to determine the relationship between strain and stress. The resulting stress-strain curve is shown in FIG. In addition, the result of FIG. 5 is a stress-strain curve when 5% strain is given.

From these results, when the heat treatment was performed at a low temperature lower than the shape memory heat treatment temperature specified in the present invention, no plateau region appeared in both the No. 1 material and the No. 2 material, and the bending load was reduced. It shows a tendency to increase with the increase, and is less supple. Conversely, when the heat treatment temperature is high, the crystal structure slips due to a large deformation with a decrease in the transformation point, and the superelastic property is deteriorated. On the other hand, when the heat treatment temperature is an appropriate intermediate temperature, a plateau region associated with the stress-induced martensitic transformation appears and shows good superelastic properties.

Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be implemented in various modified forms without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing an eyeglass frame to which the present invention is applied together with the entire eyeglasses as an example.

FIG. 2 is an explanatory diagram of a test method performed for evaluating superelasticity in an example of the present invention.

FIG. 3 is a diagram showing a relationship between a shape memory heat treatment temperature and superelastic properties of a Ni-Ti-Co ternary superelastic material obtained in an example of the present invention.

FIG. 4 is a diagram showing a relationship between a shape memory heat treatment temperature and a superelastic property of a Ni-Ti binary superelastic material obtained in an example of the present invention.

FIG. 5 is a diagram showing stress-strain curves at various shape memory heat treatment temperatures obtained in an example of the present invention.

[Explanation of symbols]

 10 Eyeglass frames

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Claims (8)

[Claims] After cold-working a Ni-Ti-Co ternary superelastic material, it is formed into a predetermined eyeglass frame shape, and a shape memory heat treatment is performed while maintaining the formed shape to form an eyeglass frame. A method for manufacturing an eyeglass frame using a superelastic material, wherein the shape memory heat treatment is performed at a temperature of 400 ° C. or more and a recrystallization temperature or less at the time of manufacturing. 2. The method according to claim 1, wherein the shape memory heat treatment is performed at a temperature of 400 ° C. or more and 440 ° C. or less. 3. The superelastic material according to claim 1, wherein the superelastic material has a composition of, in weight%, Ni: 53.00 to 55.50% Co: 0.5 to 3.0% with the balance being substantially Ti. A method for manufacturing an eyeglass frame using a superelastic material. 4. A spectacle frame is manufactured by cold working a Ni-Ti binary superelastic material, forming it into a predetermined spectacle frame shape, and performing shape memory heat treatment while maintaining the formed shape. In this case, the shape memory heat treatment is performed at a temperature of 510 ° C. or more and a recrystallization temperature or less, a method for manufacturing an eyeglass frame using a superelastic material. 5. The method according to claim 4, wherein the shape memory heat treatment is performed at a temperature of 510 ° C. or more and 540 ° C. or less. 6. The superelastic material according to claim 4, wherein the superelastic material has a composition consisting of 55.80% to 56.20% Ni by weight, with the balance being substantially Ti. A method for manufacturing an eyeglass frame using a material. 7. The method for manufacturing an eyeglass frame using a superelastic material according to claim 1, wherein the shape memory heat treatment is performed for at least 15 minutes. 8. The method for manufacturing an eyeglass frame using a superelastic material according to claim 1, wherein the cold working is performed at a working ratio of 10% or more.