JPS6234620A - Cold drawing method for steel tube - Google Patents

Abstract

PURPOSE:To eliminate processes relation to pickling and chemical conversion coating and to reduce the number of processes by dipping a material to be worked into a resin base lubricating liquid after the surface of the material is formed into an irregular condition, forming a lubricant film on the surface of the material, and performing drawing. CONSTITUTION:Mechanical descalling is performed on the surface of a material to be worked to form an irregular condition on the surface and mill scale are removed. Then, the material is dipped in a resin base lubricating liquid to form a lubricant film on the surface of the material. A desirable lubricant is an acrylic one. The material provided with the above treatment is drawn to have a prescribed dimension.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for cold drawing steel pipes.

[Prior Art] Cold drawing is used for improving the dimensional accuracy or surface roughness of workpieces, improving mechanical properties, manufacturing irregular cross-section materials, and the like.

FIG. 2 is a process diagram showing a pretreatment step for drawing and pressurizing in a conventional cold drawing method. That is, in the conventional cold drawing processing method, in order to remove dirt on the surface of the workpiece, a degreasing step 21 is performed using an alkaline type degreaser, a water washing step 22, HCI, H2SO, nitrofluoric acid, etc. A pickling process 23 to remove rust and mill scale in a hot solution; a water washing process 24 to prevent contamination of the chemical conversion coating treatment solution by the pickling acid; A hot water washing step 25 to prevent deterioration, a base film treatment step 26 to form a film of phosphate and oxalate, preventing contamination by the lubricant treatment liquid and bringing the reaction between the lubricant and the film to an ideal state. A rinsing step 27 and a neutralization step 28 are carried out, a lubrication step 29 is performed to adsorb the lubricant and the metal soap formation reaction takes place, and a hot air drying step 30 is performed to improve the lubrication performance, followed by drawing 31. It is said that

[Problems to be Solved by the Invention] However, the conventional cold drawing method described above has the following problems.

The first problem is the pickling process 23. Since this method uses a chemical method, it is difficult to control the temperature, concentration, immersion time, etc. of the liquid, and the waste liquid must be disposed of, which is time-consuming and has the disadvantage of being undesirable in terms of pollution. .

The second problem is the chemical conversion treatment step 26 and the lubrication step 29. Conventionally, methods have been known in which a chemical conversion film is formed on the surface of the workpiece and a lubricant is applied in order to reduce the friction between the processing tool and the product and prevent seizure due to localized concentration of frictional heat. . Chemical coating 1 model differs depending on the material of the workpiece, ordinary steel, alloy steel has phosphate coating, high alloy steel,
Stainless steel is known to have an oxalate film, and animal and vegetable oils, mineral oils, extreme pressure additives, etc. are used as lubricants.

These chemically reactive lubricants are difficult to manage, and
It has a short lifespan, and it has the disadvantage that the treatment liquid cannot be used to treat substrates ranging from ordinary steel to stainless steel, so it is necessary to change the treatment liquid depending on the material. Furthermore, even the oxalate coating, which is suitable for high CrW4 and difficult-to-process materials, does not provide sufficient adhesion, and it is necessary to increase the liquid concentration and soaking time to improve adhesion. However, it still has the disadvantage that the expected film cannot be obtained and seizure may occur during pulling out.

The third problem is that the number of steps required before drawing is large, resulting in a significant increase in manufacturing costs.

Among these problems, in order to solve the second problem, for example, there is a "cold drawing method for difficult-to-process materials" disclosed in Japanese Patent Application Laid-Open No. 1138420/1983. The technical content of this method is to first perform shot blasting on the material surface, then apply a chemical conversion coating using oxalate, then apply a resin coating, and then apply or not apply an oil-based lubricant. A cold drawing process is performed from the raw material. By this method, even if Cr-containing difficult-to-process machining can be performed with high production and high yield, the first and third problems raised by the present inventors still remain unsolved.

The present invention solves the first to third problems mentioned above, eliminates the steps related to pickling and chemical conversion coating, which have been eternal problems in the past, significantly reduces the number of steps, eliminates complicated liquid management,
Furthermore, the object is to provide a cold drawing process that can stably perform cold drawing from ordinary steel to stainless steel using l-liquid, and can achieve a significant reduction in manufacturing costs. shall be.

[Means for Solving the Problems] The method for cold drawing steel pipes according to the present invention includes forming the surface of a workpiece into an uneven shape, immersing the workpiece in a resin-based lubricant liquid, and After a lubricant film is attached to the surface of the workpiece, the workpiece is stretched.

[Operation] According to the present invention, it is possible to eliminate the steps related to pickling and chemical conversion coating, and form a strong lubricant coating on the surface of the workpiece.

[Example] FIG. 1 is a process diagram showing a pretreatment process for drawing according to an example of the wood spring 11.

That is, in this example, first, mechanical descaling is performed on the surface of the workpiece. This is to form irregularities on the surface due to the adhesion tendency F of the lubricant in the next process, and to prevent rust and milling. The first step is to remove scale. This treatment may be performed by either sandblasting or sea-shot blasting.

Following the above-mentioned unevenness forming process, lubrication 12 is performed. This lubricant is a resin-based lubricant, and may be either a solvent type or a water-soluble type, but from the viewpoint of the working environment and ease of handling, a water-soluble type is used. is preferred. The above-mentioned lubricant is preferably made of acrylic resin, and a specific example of this lubricant is rTNKJ manufactured by 1 Nippon T Oil Co., Ltd. The method for applying the lubricant is to soak it for about 5 minutes, and in order to ensure sufficient adhesion to the workpiece, the workpiece is shaken, and then the liquid is drained and drying step 13 is performed.This drying is carried out at 100°C. This process is performed for 40 to 80 minutes before and after to form a strong lubricant film on the surface of the workpiece. The workpiece subjected to such treatment is subjected to drawing 14 to be processed into predetermined dimensions.

As described above, in the method according to the above embodiment, the surface of the workpiece is mechanically adjusted in advance to have an uneven matte surface, coated with a resin-based lubricant, and then dried. A strong dry lubricant skin was formed on the surface of the lubricant. Therefore, it is possible to treat a wide variety of cold-drawn base skins of ordinary steel, alloy steel, high-alloy steel, and stainless steel with one liquid, and to reliably prevent seizure during the drawing process.

Hereinafter, the concrete implementation results of the present inventors will be explained.

The materials targeted for drawing were steel (STK30), alloy steel (STB^22), 9%Cr4.22%Or
The pretreatment for the five types of steel, 5US304L, is Table 1,
As shown in Table 2, in the present invention, only the sandblasting treatment as shown in FIG. 1 was performed, whereas in the conventional method, descaling by pickling and chemical conversion coating treatment were performed according to the material as shown in FIG. 2. The drawing conditions are a drawing speed of 12 m/mir.
The area reduction rate was changed as appropriate under constant conditions of +, and the area reduction rate until the plug was seized was evaluated. Here, the area reduction rate is as shown in the following formula.

However, to and DO represent the wall thickness and outer diameter before being pulled out, and t
l and DI represent the wall thickness and outer diameter after drawing.The results are shown in Figure 1.As is clear from Figure 1, the surface is roughened to a satin-like texture by mechanical sandblasting (Rmax is 10 to 6 degrees). (m) In the method of the present invention, in which the material is made into an uneven shape, immediately treated with lubrication, and then pulled out after drying, a high-frequency surface area comparable to that of the conventional method is obtained for any material. Furthermore, the surface texture after finishing was better in the present invention than in the conventional method. It was found that there was no problem in drawing performance even when the conventional pickling method was replaced with a mechanical method for descaling.

By the way, such mechanical descaling method is used in various fields and is a conventionally known technology, but in the present invention, it can be used in combination with a lubricant as described above. This makes it even more effective.

[Effects of the Invention] As described above, the steel pipe cold drawing method according to the present invention includes forming the surface of a workpiece into an uneven shape, immersing the workpiece in a resin-based lubricant liquid, After a lubricant film is attached to the surface of the workpiece, the workpiece is stretched. Therefore, the present invention provides the first to third
Solving the problems of pickling, which has been an eternal problem in the past,
Eliminates processes related to chemical conversion coatings, greatly reduces the number of processes, eliminates complicated liquid management, and can stably perform cold drawing from steel to stainless steel with one liquid, significantly reducing manufacturing costs. It becomes possible to achieve this.

[Brief explanation of the drawing]

FIG. 1 is a process chart showing an embodiment of the present invention, FIG. 2 is a process chart showing a conventional example, and Chart 1 is a chart showing the effects of the present invention. 11...Mechanical descaling, 12...Lubrication, 13...Drying, 14...Drawing. Agent Patent Attorney Osamu Shiokawa Jite Itokane Ichisho (Method) November 3, 1980

Claims (2)

[Claims] (1) After forming the surface of the workpiece into an uneven shape, immersing the workpiece in a resin-based lubricant solution and attaching a lubricant film to the surface of the workpiece, the workpiece is A cold drawing method for steel pipes that involves stretching. (2) The method of cold drawing a steel pipe according to claim 1, wherein the lubricant is made of an acrylic resin.