JPH02104694A - Plated wire and production thereof - Google Patents

Abstract

PURPOSE:To improve the lubricity and solderability of a metal wire by successively forming an Ni plating layer and an Ag plating layer on the surface of the metal wire when a coil spring or a lead wire is produced. CONSTITUTION:An Ni plating layer 2 having superior surface hardness is formed on the surface of a steel or a core wire 1 of stainless steel wire. Since the resulting Ni plated wire has superior surface hardness but has inferior lubricity and solderability and sticks to dies by frictional heat during drawing to increase the cost of the dies, the Ni plating layer 2 is plated with Ag 3 having superior lubricity and solderability in 0.1-15mum thickness. A plated wire having improved lubricity and superior solderability is obtd. The sticking of the plated wire to dies by frictional heat during drawing is remarkably suppressed because of the improved lubricity and the service life of the dies is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plated wire used for coil springs or lead wires for precision instruments and electronic devices, and a method for manufacturing the same.

(Prior Art) A plated wire is required to have various characteristics at each stage: the wire production stage, the stage of forming the wire into a coil shape, etc., and the usage stage.

For example, in the wire manufacturing stage, after the surface of the generatrix is plated, wire drawing is performed using a die. During this wire drawing process, a strong frictional force acts on the wire surface, so the wire surface is required to have good lubricity.

On the other hand, in the forming process step, for example, taking a spring wire used as a coil spring material, a coil bending process is performed using a coil spring forming machine. This coil bending process is performed by pressing the wire against a jig called a pressing bin and forming it into a coil shape. It is necessary to have a surface hardness of .

Furthermore, when the formed and processed tamp wire is to be soldered to other parts as parts of various types of equipment, it is required that the solder has good properties (so-called good wettability with respect to solder).

[Problem to be solved by the invention]

Among these characteristics, conventional nickel-plated wire has no problems in terms of surface hardness, but has problems with surface lubricity and solderability.

For this reason, during wire drawing, the nickel of the plating material tends to seize on the die, and for example, when drawing a wire with a diameter of 0.35M, the die becomes unusable after a wire drawing process of only 2 (ly). Therefore, expensive dies made of diamond or sintered alloy must be replaced with brass ones, which increases the cost of the dies, lowers productivity, and increases manufacturing costs.

Furthermore, since soldering has poor properties, the efficiency of joining work with other parts is poor, making it difficult to assemble equipment.

Therefore, the present invention provides a plated wire and a method for manufacturing the plated wire, which can improve surface lubricity and solderability while taking advantage of the excellent surface hardness of nickel plated wire.

[Means to solve the problem]

The plated wire of the present invention has a nickel plating layer on the surface of the bus bar,
Furthermore, the surface of this nickel plating layer has a thickness of 0.1x to 1
It is made up of five silver-plated layers.

Further, the plated wire of the present invention is obtained by subjecting the plated wire having the above-mentioned double plating layer to a process before wire drawing.

Furthermore, in the method of the present invention, a nickel plating layer is formed on the surface of the bus bar, and the nickel plating layer has a thickness of 0.
1. After forming a silver plating layer of J~15Jm, I before wire drawing
It is intended to provide

[Effect]

In this way, by creating a double plating structure in which a silver plating layer with rich lubricity and good soldering properties is provided on the surface of the nickel plating layer, the drawbacks of nickel plating wire are covered, and the wire Surface lubricity and soldering properties can be improved.

Therefore, by improving the lubricity, it is possible to suppress seizure of the die during expansion and contraction processing and improve die paleness. Furthermore, improved soldering properties result in more efficient joining work with other parts.

Furthermore, by suppressing the thickness of the silver plating layer to 15 mm or less, the occurrence of surface flaws during molding due to lack of hardness, which is a disadvantage of silver, can be suppressed by the highly hard nickel plating layer.

〔Example〕

The figure shows a plated wire (hereinafter referred to as plated wire) before wire drawing.

1 is a bus bar, and the surface of this bus bar 1 is coated with a nickel plating layer 2,
Furthermore, the surface of this nickel plating layer 2 has a thickness of 0.1 to 1
5- silver plating 1Ii3 is provided to constitute a plating 11 strand of double plating structure.

This plated wire strand is subjected to expansion and contraction processing to become a product plated wire, and this product plated wire is subjected to various molding processes as required depending on the purpose and the like.

For the bus bar 1, lA11 (so-called piano wire) or stainless steel wire is used. Test examples for a double-plated wire using this steel wire as a bus bar and a double-plating wire using a stainless steel wire as a bus bar are shown below.

Test Example 1 Pre-coated steel wire for precision springs (piano wire - diameter 1.
Samples 1 to ■ in Table 1 were prepared by changing the thickness of the nickel plating layer 2 and the silver plating layer 3 for the stranded wire strands with double plating applied to the bus bar of 5M), and they were subjected to stretching processing. In addition, a prototype spring wire was produced and tested for die life, solderability, and surface flaws during the coil spring forming process.

Table 1 Each sample ~■ in the table above was passed through a straight type continuous wire drawing machine with a diameter of 12 inches (10 handling dies), and each wire was drawn to a maximum of 0.50 mm using an oil-based lubricant. The wire was drawn at high speed. The results are shown in Table 2.

Table 2 As shown in the above table, according to the double-plated wire of the present invention in which the silver plating layer 3 is provided on the outer layer, the silver plating layer 3 improves the lubricity of the surface during wire drawing, thereby reducing die life. ,
Compared to single-layer nickel-plated wire, the amount of expansion and contraction is significantly improved by more than 8 times, and die seizure is reduced even when the wire drawing speed is 1.5 to 2 times that of single-layer nickel-plated wire. did not occur. As a result, a significant increase in productivity was achieved due to reductions in die costs and loss time for die replacement, and the costs more than compensated for the storage costs for silver plating.

In addition, regarding soldering properties, the plated wire after wire drawing should be
After immersing it in a bath of solder (65% tin - 35% lead) heated and melted at 50°C for 3 seconds, it was pulled out and the area ratio to which half a liter was attached was examined. As a result, as shown in Table 2, silver plating 1i13
By providing this, the soldered area ratio was 98% or more, showing almost perfect wettability, and the appearance was extremely smooth, giving satisfactory results.

In addition, in the above test example, Sample 5-B was used as a sample in which the thickness of the silver plating layer of the plated wire was small.
Experiments have revealed that a silver plating layer thickness of 0.1 mm or more can be sufficiently effective in improving lubricity and solderability.

Roughly speaking, regarding the occurrence of surface flaws during molding, slight dent flaws occurred only in sample IV with silver plating yJ3 having a thickness of 20JJM, and the other samples I to (2) were free of flaws.

This is because the thicker the soft silver plating layer 3,
This is because the pressure applied to layer 3 becomes difficult to be supported by the hard nickel layer, causing the depression to deepen.According to experiments, the upper limit of the thickness of the silver plating layer without causing scratches is 15.
It was IJJR.

Test Example 2 Samples V to ■ in Table 3 were prepared by changing the plating layer thickness for double-plated stranded wire strands of stainless steel wire for precision springs, 5US304 base a (diameter 1.10 am),
A test similar to Test Example 114 was conducted using these.

Table 3 Each of the samples V to ■ in the above table was passed through a straight type continuous wire drawing Il (10 handling dies) with a block diameter of 12 inches, and each was drawn at the maximum wire drawing speed to 0.35a using an oil-based lubricant. I made a line. The results are shown in Table 4.

Table 4 As shown in the table above, for plated wires made of stainless steel wire, as in Test Example 1, die life and soldering properties can be significantly improved by improving surface lubricity, and this is also a problem with silver plating. It has become clear that surface flaws can be prevented from occurring during certain molding processes.

Incidentally, the thickness of the nickel plating layer 2 is determined primarily from the viewpoint of improving corrosion resistance. That is, when the bus bar itself is a stainless steel wire with high corrosion resistance, sufficient corrosion resistance can be ensured by setting the nickel plating thickness at the bare wire stage to a minimum of 0°3jiIA. - When H1 steel wire (piano wire) is used as the bus bar, improvement in corrosion resistance is required, so a thickness of 25 uIA or more is required to prevent red rust from occurring in 32 hours of actual spraying in a salt spray test, and pinholes etc. Considering safety and 30. m or more is considered appropriate.

- On the other hand, wire drawing is performed to reduce the wire diameter and at the same time impart high strength through work hardening. In particular, since it is an essential condition for spring wires that the coil curl be stable, it is necessary to stretch the wires with a high area reduction rate of 75% or more in order to satisfy JIs standards.

When the plated wire east wire of the present invention is used as a spring wire, it is tempered by draining or annealing treatment, and then subjected to wire drawing at an area reduction rate of 75% or more. Therefore,
The plating layer thickness b changes due to stretching, for example, after stretching with an area reduction rate of 75% (diameter becomes 1/2),
That is, at the product plating stage, the thickness of the silver plating layer 3 is half the thickness before wire drawing (plated wire stage), that is, 0.
It ranges from 0.05 to 7.5*.

(Effects of the Invention) As described above, according to the present invention, a double plating structure is provided in which a silver plating layer with rich lubricity and good solderability is further provided on the surface of the nickel plating layer. This can cover the shortcomings of nickel-plated wire and improve the ffl slipperiness and solderability of the wire surface.

Therefore, it is possible to suppress the seizure of the die before wire drawing and significantly improve the life of the die, thereby reducing die costs and improving productivity. , it is possible to improve the efficiency of joining work by half-tn bonding with other parts and improve assembly efficiency.

Furthermore, by suppressing the thickness of the silver plating layer to 15 mm or less, the occurrence of surface flaws during molding due to lack of hardness, which is a disadvantage of silver, can be suppressed by the highly hard nickel plating layer. Therefore, it is possible to suppress the occurrence of surface flaws due to processing pressure during a forming process such as coil spring forming.

[Brief explanation of the drawing]

The figure is a sectional view of the plated wire of the present invention. 1... bus bar, 2... nickel plating layer, 3... silver plating layer. Patent applicant: Tsuyoshi Nishimura
Patent Attorney Etsushi Kotani Patent Attorney Chief 1) 1

Claims (1)

[Scope of Claims] 1. A plated wire comprising a nickel plating layer on the surface of the bus bar, and a silver plating layer having a thickness of 0.1 μm to 15 μm on the surface of the nickel plating layer. 2. A plated wire, which is obtained by subjecting the plated wire according to claim 1 to a wire drawing process. 3. Form a nickel plating layer on the surface of the bus bar, and further coat the surface of this nickel plating layer with a thickness of 0.1 μm to 15 μm.
A method for manufacturing a plated wire, which comprises forming a silver plating layer and then subjecting it to wire drawing.