JPS58138513A - Production of steel wire having excellent spring workability - Google Patents

Abstract

PURPOSE:To improve the lubricity of the surface of a steel wire and to produce the steel wire having excellent workability by forming a zinc phosphate film relatively thickly on the steel wire, drawing the wire and allowing the suitable zinc phosphate film to remain and stick on the surface of the steel wire. CONSTITUTION:A high carbon steel wire such as oil-tempered wire is pickled and is then applied with a zinc phosphate film treatment. The above-mentioned zinc phosphate film having at least 2mum thickness and havng uniform thickness of about <=+ or -20% variation in the thickness in the circumferential direction is allowed to remain and stick on the surface of the steel wire after drawing, whereby the seizure, clattering, etc. of the wire surface are prevented due to decreased friction by the lubricity that the film exhibits between a working tool and the steel wire in the stage of working the wire into a spring at a high speed, and the high speed working for spring is made possible. The resultant coil spring has excellent quality having less variations in free length and coil diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a steel wire with excellent spring workability used for coil springs.

Spring steel wire, including oil-tempered wire, has poor lubricity on the wire surface, and the higher the strength, the more likely the wire surface will seize or chatter if spattered at high speed. In addition, the free length and coil diameter of the coil spring vary widely, making it difficult to process the spring at high speed, making it impossible to increase productivity. Another drawback was that it generated chattering noise, which worsened the working environment.

For this reason, in the past, the surface of the steel wire was plated with nickel to improve its lubricity and enable high-speed spring processing, but this method had the disadvantage of being expensive.

The present invention was made to solve the above-mentioned drawbacks, and
By attaching a suitable residual zinc phosphate film after wire drawing, the lubricity of the wire surface is improved, and a method for manufacturing steel wire with excellent spring workability that allows high-speed spring processing is provided. This is what I am trying to do.

The present invention is a method for producing a steel wire with excellent sputtering properties, which is characterized in that the steel wire is pickled and then treated with a zinc phosphate coating, which is then coated on the surface of the wire. It is.

The steel wire used in the present invention is a high carbon steel wire such as a wire used for coil springs, a piano wire, or a hard steel wire.

Conventional zinc phosphate coating treatment only takes into account the lubrication effect during wire drawing of steel wire, but does not take into account the lubrication effect during spring processing in the product. Therefore, the film thickness is thin, and even if a sufficient lubrication effect is obtained during wire drawing, lubrication becomes insufficient during spring processing, causing the problems mentioned above, making it difficult to process springs at high speeds, and reducing high productivity. I couldn't raise it.

The present inventors varied the thickness of the zinc phosphate coating after pickling the steel wire, and investigated the thickness of the zinc phosphate coating remaining on the wire surface after wire drawing. As a result of investigating the influence on spring workability, we found that after wire drawing, a zinc phosphate film with a thickness of at least 2 μm or more and a uniform thickness in the circumferential direction is attached, making it difficult to work with springs. It was found that a lubricating effect was exhibited between the tool and the steel wire, and excellent spring workability was exhibited. If the film thickness is less than 2 μm, or if the average thickness is 2 μm or more but the thickness is not uniform, the required lubricating effect cannot be expected. Here, uniform thickness means that the variation in thickness in the circumferential direction is ±20% or less.

Example: 5i-Cr steel oil tempered wire for valve springs of 5.8 MM/mm as steel wire (J I S G 8566, CO, 5
6%, Si 1.48%, Cr0062%), and after pickling treatment, υ/acid zinc treatment was applied, and the film thickness was conventional and thick and uniform (invention). Created. The thickness was adjusted by controlling the treatment time and the concentration of the treatment liquid.

Table 1 shows the thickness of the zinc phosphate coating after these steel wires were drawn to a thickness of 4.5 ITS/min and the variation in the circumferential direction.

Table 1 shows that the film according to the present invention has an average film thickness of 2 μm or more with little variation, but the conventional example has a small thickness and large variation.

Next, these steel wires were processed into coil springs with an inner diameter of 25 m+ and a pitch of 10 m using a coiling machine at a linear speed of 83 m/min, and the free lengths thereof were measured as shown in Table 2.

Table 2 From Table 2, it can be seen that in the case of the present invention, the variation in free length is very small compared to the conventional example, and a coil spring with accurate shape and dimensions can be obtained at high speed.

As described above, in the method of the present invention, after drawing a steel wire, the zinc phosphate film having a thickness of at least 2 μm and having a uniform thickness in the circumferential direction is left on the surface of the steel wire. By doing so, during high-speed spring processing, the coating exhibits lubricity between the processing tool and the steel wire and reduces friction, making it possible to perform high-speed spring processing without causing seizure or chatter on the wire surface. At the same time, it is possible to obtain a coil spring of excellent quality with less variation in the free length and coil diameter of the coil spring, so that it is possible to manufacture a steel wire for springs with excellent spring workability.

Claims (1)

[Claims] (1) A method for producing a steel wire with excellent spring workability, which is characterized in that the steel wire is pickled, then treated with a zinc phosphate film, and then drawn and then thickened on the surface of the steel wire.