JPH07269619A - Shape memory micro spring and manufacture of it - Google Patents

Abstract

PURPOSE:To realize a shape memory microspring and a manufacture of it suitable for a constituent part such as a micromachine, a multifunctional cathe ter, etc., extremely small, and excellent in responsiveness of extension and contraction. CONSTITUTION:In a micro spring wherein the outside diameter of a coil using an element wire made of shape memory metal whose outside diameter is 100mum or less is 500mum or less, the coil pitch is taken as l to 10 times of the outside diameter of the element wire, the mean diameter of the coil is taken as Do, and the element wire diameter is taken as (d), thereby the spring index C shown by Do/d is selected within the range of 1.5 to 10. And, the element wire diameter (d), the coil outside diameter D, the coil pitch P, and the spring index C within the specific range are integrally unseparable and excellent in responsiveness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a coil wire diameter of 100.
The present invention relates to a shape-memory microspring having a coil outer diameter of less than or equal to μm and a coil outer diameter of less than or equal to 500 μm, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a micro spring having a coil outer diameter of about 500 μm or less, there is one formed by using an ultrafine metal wire such as stainless steel. When using such a spring as one of the components such as a micromachine and a multi-function catheter that perform various treatments by inserting it into a blood vessel of a human body, there is no problem in size, but only normal spring operation is possible. Since it is not shown, it is not possible to freely control the expansion and contraction of the spring from a remote location regardless of external force. Therefore, it is basically unsuitable as a component such as the above-mentioned micromachine or catheter, which is required to have multiple functions with as few components as possible.

On the other hand, a spring of a normal size using a shape memory metal is also known. The shape memory spring can be expanded or contracted only by applying a temperature change by electrically heating the spring regardless of an external force. The conventional shape memory spring is focused only on the fact that it can be expanded and contracted by temperature change, and its high speed of operation, that is, good responsiveness does not pose a problem, and it is mainly used for applications where high speed responsiveness is not required. Shape memory springs have been developed.

[0004]

The springs used in applications such as micromachines and multifunction catheters are minute and can be controlled to extend or contract from a remote location, and when the spring is heated or cooled. It is required to have a high-speed response in which the spring expands and contracts instantly. In particular, high-speed responsiveness is the most important factor in achieving high functionality of micromachines and the like. However, at present, no microsprings satisfying the above demands have been proposed, which is a hindrance to the practical use of the above micromachines, multifunctional catheters and the like. Therefore, an object of the present invention is to provide an extremely minute shape memory microspring which is suitable as a component such as a micromachine or a multi-function catheter and has excellent response of expansion and contraction, and a manufacturing method thereof.

[0005]

The shape-memory microspring of the present invention is a microspring having an outer diameter of 100 μm or less and a coil made of a shape-memory metal having an outer diameter of 500 μm or less. Pitch is 1 to 10 of wire outer diameter
And the average coil diameter is D ₀ and the above wire diameter is d
And the spring index C represented by D ₀ / d is 1.5 to 1
It is characterized in that the range is 0. The present inventors have found that by configuring the spring so as to satisfy all the above requirements, a shape memory microspring having a high-speed response of expansion and contraction that can be sufficiently provided for practical use is realized.

First, when the outer diameter of the wire made of a shape-memory metal shown by symbol d in FIG. 1 exceeds 100 μm or the outer diameter D of the coil exceeds 500 μm, the basic purpose is to make the spring microscopic. However, as a matter of course, the response due to the temperature change of the spring deteriorates. That is, the response speed depends on the heating / cooling speed of the shape memory micro spring itself, and the heating / cooling speed, especially the cooling speed depends on the heat capacity of the spring. Therefore, the smaller the heat capacity, the better the responsiveness. As a result of repeating various experiments based on the assumption that the above, it was found that when the outer diameter of the wire and the outer diameter of the coil are in the above ranges, the wire can withstand practical use.

That is, when the outer diameter d of the wire exceeds 100 μm and the outer diameter D of the coil exceeds 500 μm, the heat capacity of the spring increases and the responsiveness deteriorates. On the other hand, if these are too small, it is not desirable because the manufacturing difficulty increases, so the preferred outer diameter of the wire is 10 to 80 μm.
In particular, it is 20 to 70 μm, and the preferable coil outer diameter is 50 to 300 μm, especially 80 to 200 μm.

Further, it has been found that not only the outer diameter of the wire and the outer diameter of the coil, but also the coil pitch and the spring index thereof must be selected within appropriate ranges in order to improve the response. That is, the coil pitch P is 1 to 1 of the wire outer diameter d.
It is necessary that the spring index C is in the range of 0 times, and the spring index C represented by D ₀ / d is in the range of 1.5 to 10 when the coil average diameter is D ₀ and the strand diameter is d.

In other words, the coil pitch P specifies the extension range of the spring, and means the range in which it can be extended to the maximum in either the normal temperature state or the shape recovery state. For example, a state in which the shape memory micro spring is completely reduced (in this case, the coil pitch P = the outer wire diameter d).
Is used as the shape memory mode, and when the spring is normally used in a stretched form, the coil pitch P when the spring is stretched is set to be 10 times or less at the longest. On the contrary, when the expanded state is the shape memory mode, the pitch is set to be equal to or less than the above-mentioned pitch.
If the coil pitch P exceeds 10 times the outer diameter d of the strand, the response speed tends to be slow and the original spring property is deteriorated. The coil pitch P preferable for the purpose of higher speed responsiveness is 1 to 8 times, especially 1 to 6 times the outer diameter d of the wire.

The spring index of an ordinary spring is appropriately selected according to the required expansion / contraction force, etc., but it is extremely fine like the shape memory micro spring of the present invention, and the expansion / contraction operation changes with temperature. It is necessary to set a specific range in the special spring that is achieved by the above and requires high-speed response. The spring index C that can achieve this requirement is 1.5 to 10
And preferably 1.7 to 8, particularly 2 to 6. When the spring index C is 1.5 or less or 10 or more, the response speed decreases, and in the former case, the mechanical rigidity increases and the shape recovery force due to temperature is impeded. In this case, it is considered that the spring shape is likely to be distorted when the shape is recovered.

As will be apparent from the examples described below, the shape of the present invention is excellent in responsiveness because the outer diameter d of the wire, the outer diameter D of the coil, the coil pitch P and the spring index C in the above-described specific range are inseparable. A memory micro spring is realized.

The shape memory metal is not particularly limited, but the preferable one is Ni: 49 to 51 at%, T.
i: 51-49 at% Ni-Ti alloy,
Alternatively, it is a shape memory alloy composed of Cu: 10 to 30% by weight, Zn: 3 to 10% by weight, and the balance Al being a Cu-Zn-Al alloy. These shape memory alloys are essentially excellent in transformation characteristics associated with temperature changes and can be suitably used for the spring of the present invention.

The total length of the spring is preferably selected within the range of 3 to 1000 mm. A spring that is too short is not preferable because it exhibits only a slight expansion and contraction action because it is a spring that uses the above-specified specifications and shape memory characteristics, and a spring that is too long has a slow response. Therefore, it is not preferable. For this reason, the more desirable total length is 5 to 100 mm, and from the viewpoint of incorporation into a micromachine or a catheter, about 7 to 30 mm is preferable.

On the other hand, in the method for manufacturing a shape memory microspring according to the present invention, the high-strength core wire having an outer diameter of 500 μm or less and rotating about its axis is made of a shape memory metal having an outer diameter of 100 μm or less. 1.5-300g of wire
It is characterized in that the coil obtained by winding with the rotational force of the core wire while applying the back tension of f and heat-treating the coil is obtained.

Preferably, the rotation of the core wire is performed by holding the high-strength core wire between a pair of chucks that rotate in synchronization, and the winding pitch of the wire around the core wire is 1-10 outer diameters. It is desirable to select in the double range.

FIG. 2 shows an example of a manufacturing apparatus for achieving the manufacturing method of the present invention. In the figure, 1 is a high-strength core wire,
For example, a stainless wire such as SUS304 or a wire having a tensile strength equal to or higher than that of the stainless wire is used. Further, 2 is a coil wire, which is the above-mentioned Ni-
A shape memory metal wire made of a Ti alloy, a Cu-Zn-Al alloy, or the like is used. The outer diameter of the core wire 1 is selected in the range of 500 μm or less in order to manufacture a spring having a coil outer diameter of 500 μm or less. For example, the outer diameter of the wire 2 is 5
In the case of 0 μm, the core wire 1 is selected to be 400 μm or less in consideration of a desired spring index and the like.

The core wire 1 is constructed so as to rotate about its axis, and the wire 2 is wound around the core wire 1 in a coil shape by this rotational force. The rotating means is not particularly limited, but in the example of FIG. 2, holding both ends of the core wire 1,
In addition, an example using a pair of chucks 31 and 32 that rotate synchronously is shown. According to this method, there is an advantage that the core wire 1 which is very thin can be stably rotated without bending, and the core wire 1 can be easily attached and detached. The rotation speed of the chucks 31 and 32 is appropriately selected within the range of 1500 rpm or less.

Reference numeral 4 denotes a wire supply device, which supplies the wire 2 to the core wire 1 while applying a predetermined back tension to the wire 2. The strand supply device 4 is movable in a direction parallel to the core 1. The back tension given to the wire 2 is 1.5
It is necessary to select in the range of up to 300 gf. When the tension is smaller than the above, the strand 2 is apt to bend and it is difficult to tightly wind the core 1, and when it is larger than the above, the strand 2 is easily broken. . In the example of FIG. 2, the case where three tension rolls 41 are used as the tension applying means is shown.

When actually manufacturing a spring, the chuck 3 is used.
The rotation speeds of 1, 32, the back tension on the wire 2, and the winding pitch of the wire 2 around the core 1 are controlled according to the outer diameter of the wire and the desired spring index. The pitch control may be performed by adjusting the moving speed of the wire supply device 4. In addition, the wire feeder 4 is fixed and the chucks 31, 32
May be moved in parallel according to the pitch. The pitch is 1 to 10 of the outer diameter of the wire due to the reason described above.
It is desirable to select in the double range.

The coil obtained as described above is then subjected to heat treatment in order to impart shape memory property. This heat treatment is, for example, at 350 ° C. for about 1 hour when a Ni—Ti alloy wire is used as the wire 2.

When the shape memory micro spring is used, as a means for controlling the expansion and contraction of the spring from a remote location, for example, a laser beam can be applied to the spring via an optical fiber. The simplest and rational control is to restore the shape of the spring to the shape memory shape that is contracted or expanded by heat, and to expand or contract by stopping irradiation, or to control the spring itself to be electrically expanded and contracted in the same manner. Is the way.

[0021]

【Example】

(Examples 1 to 6 and Comparative Examples 1 to 5) Ni: 4 as a wire rod
SUS3 having an outer diameter of 9.5 at% and Ti: 50.5 at% of Ni-Ti alloy is used, and the apparatus shown in FIG. 2 is used to obtain the wire outer diameter and the coil outer diameter shown in Table 1.
Using each of the 04 core wires, the wire was tightly wound around the core wire (winding pitch = 1) to produce a coil. After heat-treating the obtained coils at 350 ° C for 1 hour to memorize the shape, each coil is cut into a certain length (30 mm) and stretched to 45 mm to obtain 11 shape-memory microsprings. Created.

(Responsiveness Evaluation Test) As shown in FIG. 3, a flange portion 61 is provided in the cylinder 5, a front portion of which accommodates a piston 6 which can project from the cylinder 5, and a rear portion of the flange portion 61 is provided. The bias spring 62 was set such that the shape memory microspring 20 obtained above was arranged on the front side and the bias spring 62 and the shape memory microspring 20 were attracted to each other. Further shape memory micro spring 2
An optical fiber 7 for irradiating laser light to the laser light 0 was arranged on the side wall of the cylinder 5. Further, in front of the piston 6, an optical sensor 8 composed of a pair of array type light emitting and receiving devices is arranged so that the light projecting path is blocked when the piston 6 projects.

Then, the light emitting and receiving of the light sensor 8 is monitored, and when the light emitting path of the light sensor 8 is completely shielded by the forward movement of the piston 6, a switch of a laser light source (not shown) connected to the other end of the optical fiber 7 Is set to OFF, and the laser light source switch is set to ON when the projection path of the optical sensor 8 is completely released due to the backward movement of the piston.

Using this measuring device, in order to confirm the responsiveness of the spring, the number of strokes of the piston 6 per minute (the number of times of complete light shielding in the optical sensor 8) for each of the 11 shape memory microsprings obtained above was determined. ) Was measured. The results are shown in Table 1.

[0025]

[Table 1]

[0026]

As described above, according to the shape memory micro spring of the present invention and the method for manufacturing the same, it is possible to obtain a shape memory micro spring which is extremely excellent in response to expansion or contraction of the spring when a temperature change is applied. Obtainable. Therefore, when the spring of the present invention is incorporated into a micromachine, a multifunction catheter, or the like, various operations can be performed at high speed, and a more sophisticated and highly functional micromachine or multifunction catheter can be realized.

[Brief description of drawings]

FIG. 1 is a side view showing a shape memory micro spring of the present invention.

FIG. 2 is a perspective view showing an example of a manufacturing apparatus for realizing the manufacturing method of the present invention.

FIG. 3 is a cross-sectional view of a measuring device for evaluating responsiveness.

[Explanation of symbols]

 1 Core Wire 2 Elemental Wire Made of Shape Memory Metal 20 Shape Memory Micro Spring 31, 32 Chuck

Claims (7)

[Claims] 1. A microspring having a coil outer diameter of 500 μm or less, which uses a wire made of a shape-memory metal having an outer diameter of 100 μm or less, and a coil pitch of 1 to 1 of the wire outer diameter.
When the coil average diameter is D ₀ and the strand diameter is d, the spring index C represented by D ₀ / d is 1.5 to 0.
A shape memory micro spring having a range of 10. 2. The shape memory metal is Ni: 49-5.
The shape memory micro spring according to claim 1, which is made of a Ni-Ti alloy containing 1 at% and Ti: 51 to 49 at%. 3. The shape memory metal is Cu: 10 to 3
0% by weight, Zn: 3 to 10% by weight, balance Cu-Z of Al
The shape memory micro spring according to claim 1, which is made of an n-Al alloy. 4. The shape memory micro spring according to claim 1, wherein the total length of the spring is in the range of 3 to 1000 mm. 5. A high strength core wire having an outer diameter of 500 μm or less and rotating about its axis has an outer diameter of 100 μm.
A wire made of the following shape-memory metal is used for 1.5 to 300
A method for manufacturing a shape-memory microspring, which comprises winding with the rotational force of the core wire while applying a back tension of gf and heat-treating the obtained coil. 6. The method of manufacturing a shape memory microspring according to claim 5, wherein the core wire is rotated by holding the high-strength core wire between a pair of chucks that rotate synchronously. 7. The method for manufacturing a shape memory microspring according to claim 5, wherein the winding pitch of the wire around the core wire is selected within a range of 1 to 10 times the outer diameter of the wire.