JP2000274467A - Wire for spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire for a spring made of a beryllium copper alloy of quality, being stable at a high level, at a low cost. SOLUTION: The outer periphery of a core 1 of a beryllium copper alloy is covered with a copper outer layer 2 formed of copper having high stability. Provided the section area of the core 1 is A1 and the section area of the outer layer 2 is A2, an outer layer ratio represented by [A1/(A1+A2)]×100 is specified to 0.5-5.0%. A range of 0.03-0.20 mm preferable as the diameter of a wire for a spring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring used for precision equipment and electronic equipment, and more particularly to a fine spring wire which can be suitably used for a spring for a contact probe or the like which requires excellent conductivity and corrosion resistance. Things.

[0002]

2. Description of the Related Art Various types of spring wires, which are described in detail below, are provided in a manufacturing stage, a step of forming (coiling) the spring wire into a spring, and a stage of using the spring wire as a spring. Characteristics are required.

[0003] For example, in the manufacturing stage, the wire surface is reduced in diameter by cold wire drawing with a severe reduction in area, so that the wire surface has excellent lubricating properties to reduce a large frictional force acting on the wire surface. is there. In the spring forming step, coil winding is performed by a coil spring forming machine. At this time, a frictional force acts between the wire and the jig, so that the surface of the steel wire can be easily slipped. It is necessary to be. Further, when the thus formed spring is joined to other parts as a part of various devices, it is necessary to have good brazability with solder, silver solder, or the like. Furthermore, at the stage of using as a spring, a spring for electronic equipment, particularly a spring wire used for a contact probe, is required to have excellent conductivity.

Under these circumstances, as a spring wire of this type, a nickel-plated spring steel wire in which a nickel plating layer is provided on the surface of a steel wire such as a high-carbon steel wire or a piano wire is currently widely used. ing. The spring steel wire is manufactured by subjecting the steel wire to a lead patenting process, a nickel plating process, and then performing a cold drawing process. But,
This spring steel wire has the following problems. That is, lubricity during wire drawing is not sufficient. For this reason, seizure with the die is apt to occur, shortening the service life of the expensive die made of diamond or sintered alloy, and increasing the frequency of die replacement, which increases the cost of the die and complicates workability. And the production cost rises. Also,
The coiling property (slipperiness) at the time of spring forming is not sufficient, and the brazing property is also poor. For this reason, the workability of spring forming and joining with other parts is poor,
Yield is significantly reduced. Furthermore, little consideration is given to the point of conductivity. For this reason, especially when used for a spring for electronic equipment such as a contact probe, the performance as a spring for electronic equipment is insufficient.

Therefore, recently, a beryllium copper alloy has been developed as a new spring material. This is because by adding several percent beryllium to copper, it is possible to achieve several times the strength of copper, and it has age hardening properties, good electrical conductivity, excellent corrosion resistance and wear resistance, This is because the beryllium copper alloy is effective as a material for a spring for electronic devices because it has excellent properties such as little change and strong fatigue. However, since the beryllium copper alloy is an alloy that is extremely easily oxidized, a hard thin film of beryllium oxide is formed on the surface in room temperature air, and seizure occurs due to oxidative heat, resulting in extremely poor drawability. For this reason, in the conventional production of thin metal wires, beryllium copper wire is melt-cast in a vacuum, subjected to a forging process, then repeatedly subjected to heat treatment and wire drawing, and then is softened and homogenized by solution treatment. In general, a step of obtaining a desired strength by wire drawing in an oxygen-free atmosphere gas and subsequent age hardening treatment is employed (for example, Japanese Patent Application Laid-Open No. 4-187351).

[0006]

However, in the above-described conventional wire drawing, it is difficult to control the atmosphere gas and it is not possible to completely prevent the formation of a beryllium oxide film.
Therefore, the activity (oxidation) of beryllium is high. Therefore, equipment costs and maintenance costs for controlling the atmosphere are high. In addition, the oxide film shortens the life of the wire drawing die, adversely affects the wire quality, increases the frequency of die replacement, and increases the die cost. because of these reasons,
There is a problem that the quality is unstable and the spring wire becomes expensive. Accordingly, an object of the present invention is to provide a beryllium copper alloy spring wire having a low cost and a high level of stable quality.

[0007]

In order to achieve the above object, a spring wire according to the present invention is provided with a copper outer layer on a core material made of a beryllium copper alloy, and the outer layer ratio of the copper outer layer is 0.5 to 0.5.
5.0%.

According to this method, since the outer periphery of the core material made of a beryllium copper alloy is covered with a highly stable copper outer layer, the production of beryllium oxide is prevented even when exposed to outside air. In the present invention, the outer layer ratio is defined as [A2 / A1] where A1 is the cross-sectional area of the core material and A2 is the cross-sectional area of the outer layer.
(A1 + A2)] × 100.

The reason why the outer layer ratio is set in the range of 0.5 to 5.0% is that in the case of this kind of spring wire, if the outer layer ratio is less than 0.5%, the thickness becomes thin and the core material becomes outside air. , The generation of beryllium oxide cannot be prevented, and if it exceeds 5.0%, the protective effect is hardly improved and the strength is weakened.

The diameter of the spring wire is 0.03.
A range of .about.0.20 mm is preferred. Wire diameter is 0.03m
If it is less than m, it is difficult to secure the strength and elasticity of the spring, and in the field of precision equipment and electronic devices, which are rapidly becoming micro-sized in recent years, springs for contact probes have also been reduced in diameter. This is because if the diameter exceeds 0.20 mm, it becomes impractical, but it is not limited to this range depending on the application.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spring wire according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the spring wire of the present invention has an outer layer ratio of 0.5 to 5.
The copper outer layer 2 adjusted to be in the range of 0% is provided. As a raw material of the core material 1, a ternary alloy or a quaternary alloy, for example, Cu-Be-Ni, Cu-
A beryllium copper alloy such as Be-Co or Cu-Be-Co-Ni is used. In the spring wire for the contact probe, the addition amount of each additive component is adjusted in order to achieve both strength and conductivity. For example, when the amount of Be is increased, the strength is increased. On the other hand, a material with a small amount of Be has good electric conductivity. Further, the addition of Co plays a role of suppressing crystal growth and providing uniform heat treatment. An appropriate type of beryllium copper alloy may be selected in consideration of these points.

By the way, as a commonly used beryllium copper material, 25 alloy (C17200), Be content;
1.80 to 2.00% by weight or 11 alloy (C1751
0), Be content; 0.2 to 0.6% by weight, etc.
What is necessary is just to use properly considering the balance of conductivity and strength according to a use.

Means for providing a copper outer layer on the outer periphery of the beryllium copper alloy include a method by plating, a method of covering with a copper pipe, a method by sputtering, and the like, and these may be appropriately used depending on the use and production amount. . For example, it is preferable to adopt a method for obtaining a relatively thick outer layer, or a method for obtaining a thin film having relatively few pinholes, if a continuous facility is used.

Next, a beryllium-copper alloy wire having a copper outer layer provided by any of the above-mentioned means is applied to a wire having a wire diameter of 0.08 to 0.20.
By drawing the wire up to mm, a spring wire having an outer layer ratio adjusted to a desired range can be obtained. In this case, the ratio of the outer layer can be in a desired range by appropriately adjusting and selecting the thickness of the copper outer layer provided by the above-mentioned means and the drawing conditions (degree of drawing, die shape, die series, etc.). . Further, as the drawing method, wet drawing is preferable to dry drawing. This is because in the wet drawing, the drawn material is cooled by the lubricating liquid by the full immersion method or the shower method. According to this wet drawing, the heat of drawing
Beryllium can be prevented from diffusing into the copper outer layer due to a diffusion reaction between the core material and the copper outer layer.

[0015]

EXAMPLE A C17510 beryllium copper alloy was selected as a test material. The chemical composition of this material is in weight%, Be;
0.35, Ni; 1.62, Co; 0.08, Fe;
0.03, Si; 0.02, Al; 0.02, balance Cu
It is. A 0.60 mm annealed material of beryllium copper of the above chemical component was used as a base wire, and copper having a thickness of 3.1 μm was applied thereto by electroplating. Next, 0.20 by wet wire drawing machine
The wire drawn to a depth of 0.1 mm was subjected to a solution treatment at 900 ° C., and further drawn to 0.10 mm by wire drawing to produce a spring wire according to the present invention having an outer layer ratio of 2.2%. Note that an inexpensive N2 gas was used as an atmosphere gas during the heat treatment.

In addition, several other spring wires having an outer layer ratio outside the range of the present invention and several spring wires of a comparative example having an outer layer ratio outside the range of the present invention were manufactured. Further, a conventional spring wire was manufactured by drawing a wire which had been pickled after solution treatment in an non-oxidizing atmosphere. Next, an energizing spring for a contact probe was manufactured using the spring wires of these examples, comparative examples, and conventional examples. Then, the comparison in each step and the comparison as a spring wire were performed. Table 1 shows the results.

[0017]

[Table 1]

In this table, the die life coefficient is a value obtained by comparing the die life at the time of wire drawing of the conventional example of Experiment No. 6 with a larger value. Regarding spring formability, spring conductivity, and spring strength, ◎, ○, △, ×
The superiority and inferiority were compared by the four-step evaluation. Δ and × indicate cases where there is a problem in practicality. According to Table 1, it is understood that the die wear during the wire drawing is reduced particularly at the copper plating ratio of 0.6 to 5.0%, and a remarkable effect is recognized at 2 to 5%. Also, the conductivity of the spring is improved as compared with the conventional spring wire. Also, it was found that when the outer layer ratio exceeded 5.0%, the strength required for the probe spring could not be maintained due to a decrease in the spring strength.

[0019]

According to the spring wire of the present invention, since the copper outer layer having an appropriate outer layer ratio covers the core material of the beryllium copper alloy, the friction between the wire and the jig can be reduced during the spring forming process. Efficient spring molding is possible. Also, when used for springs for electronic equipment, especially springs for contact probes,
It has excellent conductivity, high strength, and excellent corrosion resistance. Also, in the manufacturing process of the spring wire of the present invention, inexpensive N2 gas can be used at the time of heat treatment, and at the time of wire drawing, there is no need to use an atmospheric gas as in the past, and equipment costs and management costs are reduced. Is significantly reduced. In addition, the life of the dies during wire drawing can be greatly extended. For these reasons, the manufacturing cost can be greatly reduced, so that an inexpensive spring wire can be manufactured, which is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing an embodiment of a spring wire according to the present invention.

[Explanation of symbols]

 1 core material 2 copper outer layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J059 AB04 AB06 AB14 AD05 AD06 BA01 EA04 GA21 4E096 EA04 EA13 EA26 FA01 GA03 HA08 HA11 HA21 JA13 KA09 5G307 BA03 BB02 BC03

Claims (2)

[Claims] 1. A spring wire, wherein a copper outer layer is provided on a core material made of a beryllium copper alloy, and an outer layer ratio of the copper outer layer is 0.5 to 5.0%. 2. The spring wire according to claim 1, wherein the wire diameter is 0.03 to 0.20 mm.