JP3006279B2 - Method for producing steel wire with excellent spring formability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a steel wire for a spring which has excellent spring formability and is effective for environmental protection.

[0002]

2. Description of the Related Art A steel wire for a spring which has been drawn, quenched, or tempered as it is, for example, when it is formed into a coil spring, is seized on a coiling pin of a coiling machine,
Stick-slip may occur with the pin. This is because the coefficient of friction of the surface is high, and the higher the strength of the steel wire and the higher the coiling speed, the more frequently the steel wire tends to occur.

When the seizure and stick-slip occur, the coiling speed varies, and the shape of the completed coil spring is not constant. In addition, abnormal noise (so-called chattering noise) is generated during coiling, and the working environment is deteriorated.

For this reason, this type of steel wire for springs employs a method of applying an oil agent for lubrication for a purpose other than rust prevention, that is, lubrication, but the conventional oil agent is a steel wire. The lubricating effect cannot be said to be sufficient due to the increase in molding pressure accompanying the increase in the strength of steel. Further, there is a problem such as scattering, which is not preferable in the working environment.

For this reason, the present applicant has proposed in Japanese Patent Application Laid-Open No. Hei 3-213735 that a fluorinated resin coating is provided on the surface of a wire after quenching and tempering.

However, this fluorine-based resin coating film does not scatter and has sufficiently high spring formability. However, in the indispensable spring annealing step after molding, the resin is decomposed to generate a gas containing fluorine. Is a drawback.

This gas reacts with hydrogen contained in the moisture in the atmosphere to generate hydrogen fluoride gas (HF), which has the danger of corroding the spring and is harmful to the human body. .

Therefore, the present inventors have found a coating film of an amino acid compound as one which can eliminate the above-mentioned problem of harmful gas generation during annealing heat treatment while obtaining a lubricating effect which is not much different from that of a coating film of a fluorine resin. .

[0009]

When the coating film of the amino acid compound has uneven coating or is scattered during spring molding, the lubricating effect is not sufficiently exerted, and the spring moldability may be insufficient. .

[0010] An object of the present invention is to provide a method for producing a steel wire for a spring in which a coating film of an amino acid compound which does not cause such a problem can be obtained.

[0011]

In order to achieve the above-mentioned object, the present invention relates to a quenched and tempered spring steel wire having an amino acid compound having a particle size of not less than 0.5 μm and not more than 30 μm. A method in which a solution in which the powder is dispersed in an organic solvent is applied and dried. Drying at this time may be either natural drying or forced drying.

The amino acid compound referred to here is
It is a compound of amino acids and fatty acids.
Lysine, arginine, histidine and the like, and fatty acids include acrylic acid, lauric acid, aspartic acid,
And stearic acid.

The amount of the amino acid compound applied is 3 g /
m ² or more and 15 g / m ² or less are preferable.

It is also preferable that an acrylic resin or the like is contained as a binder in the solution in which the amino acid compound is dispersed.

[0015]

The amino acid compound powder having a particle size of 0.5 to 30 .mu.m is uniformly dispersed in an organic solvent, which is effective in preventing uneven coating. A powder having a size of 0.5 μm or less is difficult to be uniformly dispersed in a solvent, and is likely to aggregate to form a large lump.
Powders and agglomerates exceeding 30 μm tend to precipitate in a solvent. Therefore, with a powder having a particle size outside the range of 0.5 to 30 μm, it is difficult to apply the solution uniformly, and uneven coating occurs, and the effect of the coating film cannot be sufficiently obtained.

Further, the coating film dried after application does not scatter, but of course does not easily peel off even when rubbed against a coiling pin of a molding machine. A spring formability that is not significantly different from that of the resin coating film can be obtained.

The reason why the coating amount of the amino acid compound is preferably 3 g / m ² or more and 15 g / m ² or less is that when the coating amount is 3 g / m ² or less, the adhesion amount is insufficient and especially in the case of high strength steel wire. , The spring formability becomes insufficient,
On the other hand, if it is 15 g / m ² or more, there is a problem of an increase in cost, and a slip or the like in the feeder roll is likely to occur, which may hinder the feeding of the steel wire.

Further, it is preferable that the binder is contained in the solution because the binder enhances the adhesive force of the amino acid-based compound, so that the film after drying cannot withstand a higher molding pressure and does not peel off. This is because the moldability is further improved.

[0019]

【Example】

(Experimental Example 1) A dried coating film of an amino acid compound was formed on the surface of a silicon chrome steel oil-tempered wire (SWOSC-V) for a valve spring having a wire diameter of 4.0 mm by the production method of the present invention.

In the manufacturing process of the spring steel wire, before winding up the quenched and tempered oil-tempered wire, a solution is continuously applied to the surface of the wire and air-dried. I took it. The solution used was prepared by dispersing a powder of N-lauroyl-L-lysine, which is a compound of an amino acid and a fatty acid, having a particle size of 0.5 to 30 μm in a low-boiling organic solvent (in this case, using trichloroethane) in which a binder was dissolved, in an amount of 10 vol. % And uniformly dispersed. This solution was applied so that the amount of the amino acid compound was about 10 g / m ² , and the solvent was evaporated by natural drying to wind up the finished coated steel wire.

Next, in order to conduct a test for confirming the effect, two types of spring steel wires for comparison were prepared using the same oil-tempered wire as used for the product of the present invention.

Comparative material 1 has a fluorinated resin film provided on the surface of the wire after quenching and tempering, and the film is made of polytetrafluoroethylene (PTF) having a particle size of 5 to 10 μm.
E) A solution obtained by uniformly dispersing the powder in a Freon solvent at a concentration of 10 vol% was applied, and the mixture was naturally dried to form a powder.

In Comparative Material 2, a bundle of steel wires wound after the quenching and tempering treatments was immersed in gear oil-based lubricating oil to form an oil film on the surface of the wires.

Each of these samples was formed by a coiling machine, and the free length of the formed spring was examined for each of 300 samples for evaluation of spring formability. The dimensions of the prepared coil spring are as follows: wire diameter: 4.0 mm average coil diameter: 25.0 mm free length: 55.0 mm total number of turns: 6.5. Table 1 shows the results of this evaluation test.

[0025]

[Table 1]

As can be seen from this table, the product of the present invention has a very small variation in free length, and is close to Comparative Material 1.

(Experimental Example 2) A solution containing the same amino acid compound as used in the product of the present invention in Experimental Example 1 was mixed with the above-mentioned SW.
It was applied to the surface of OSC-V so as to have the values shown in Table 2, and was dried.

Then, each of the obtained spring steel wires was formed by a coiling machine. The dimensions of the molded coil spring are the same as those in the first experimental example. In order to evaluate the spring formability at this time, variation in free length was examined for each of 300 samples. Table 2 also shows the results.

[0029]

[Table 2]

As can be seen from this table, the sample 1 with a small coating amount has a larger variation in free length than the other samples. However, the variation value is smaller than that of the comparative material 2 of the experimental example 1.

In Sample 5, the variation in free length was small, but a large amount of white powder was scattered during coiling, which was not preferable in terms of working environment, and there was a slight slip on the feed roll.

[0032]

As described above, according to the manufacturing method of the present invention, the coating of the amino acid compound can be provided evenly on the surface of the steel wire, thereby preventing corrosion of the product (spring) and protecting the environment. By using an amino acid-based compound that is advantageous in view of the aspect, it is possible to obtain an effect that spring moldability that is not much different from that of the fluorine-based resin film can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23C 26/00 F16F 1/02

Claims (3)

(57) [Claims] 1. A quenched and tempered spring steel wire is coated with a solution in which an amino acid-based compound powder having a particle size of 0.5 μm or more and 30 μm or less is dispersed in an organic solvent, and is spontaneously or compulsorily applied. A method for producing a steel wire excellent in spring formability, characterized by drying. 2. The method according to claim 1, wherein the amount of the amino acid compound is 3
g / m ² or more, a manufacturing method of claim 1 spring formability excellent steel wire according to coated to a 15 g / m ² or less. 3. The method for producing a steel wire excellent in spring formability according to claim 1, wherein the solution containing a binder for enhancing the adhesive force of the amino acid compound to the steel wire is used as the solution.