JPS6284820A - Method and device for cold drawing - Google Patents

Abstract

PURPOSE:To produce the product to be worked of high accuracy and high quality simply by adjusting the resin film in uniform thickness prior to the cold drawing, in case of the cold drawing of the item to be worked having resin film on the outer surface with a die. CONSTITUTION:The resin film for reducing friction is formed on the surface of a blank pipe 20 by taking up the blank pipe 20 after dipping it is the lubrication oil post of acrylic resin group in order to prevent the defective surface by the siezure in drawing due to the friction heat generation between the die 11 as a work tool and blank pipe 20, in case of the diameter reduction of the blank pipe 20 to be worked of a pipe, etc., by cold drawing. While the resin is drying the thickness of the resin layer becomes uneven due to its collection at the lower part of the outer face of the blank pipe 20, so prior to the cold drawing of the blank pipe 20 in the prescribed diameter by the die 11 and plug 12 it is subjected to a cold drawing to the product 20A having excellent dimensional accuracy and no rough surface by drawing so as to become the necessary outer diameter and thickness by the outer diameter working part 11C of the die 11, after forming the thicker part of the resin layer in uniform thickness by cutting it with the outer diameter adjusting part 11B of the die 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cold drawing method and apparatus, and particularly to a cold drawing method and apparatus for applying a dry resin film to the surface of a workpiece and performing cold drawing. The present invention relates to a thinning method and device.

[Prior Art] Generally, cold drawing is carried out to improve one-dimensional performance or surface roughness, improve mechanical properties, manufacture irregular cross-section materials, and the like.

Conventionally, in order to reduce the friction between the processing tool and the product during the drawing process and prevent seizure due to localized concentration of frictional heat, a method has been known to form a dry resin film on the surface of the workpiece and then pull it out. It is being

This method will be briefly explained below.

That is, in this method, the raw pipe obtained by hot pipe making is descaled, then immersed in a lubricating oil tank for about 5 minutes, drained, and placed in a drying tank to be thoroughly dried. After forming a strong film on the surface of the workpiece, drawing is performed to obtain a predetermined product size.

[Problems to be Solved by the Invention] However, in this method, as shown in FIG. ■ and the bottom 22 of the raw pipe 20
This causes fluid to accumulate in the area. After drying is completed, this liquid pool area becomes an area where the film thickness increases, causing non-uniformity in the thickness of the lubricating film in the circumferential and longitudinal directions of the raw pipe 20.

Here, the above-mentioned raw pipe 20 is then diced into a die 31 shown in FIG.
When the plug 32 is used for drawing, the thick part of the film exerts a pushing action on the outer surface of the raw tube 20, resulting in dimensional defects such as negative product outer diameter after drawing, and rough skin on the outer surface of the product. This results in a significant decrease in yield.

Of course, in order to solve the above problem, it is expected that it would be preferable to treat the raw tube while it is being dried while rotating, but this is not appropriate as it would complicate the equipment and increase the equipment cost.

The object of the present invention is to perform smooth cold drawing by applying a resin film to obtain a highly accurate and high quality outer diameter part of a product.

Another object of the present invention is to use a simple device to facilitate cold drawing work and obtain a product outer diameter portion with high precision and high quality.

C. Means for Solving Problems] The cold drawing method according to the present invention is a cold drawing method in which a workpiece coated with a dried resin film is cold drawn using a die. After the thick part of the resin film adhered to the workpiece is scraped off, the diameter of the workpiece is reduced by the diameter-reduction section of the die.

Further, the cold drawing apparatus according to the present invention includes a die for cold drawing a workpiece coated with a dried resin film. In addition to providing an outer diameter adjusting part for scraping off the thick film part of the resin film adhered to the workpiece, a diameter reducing part for reducing the diameter of the workpiece is provided on the exit side of the outer diameter adjusting part of the die. This is what I did.

[Function] According to the cold drawing method according to the present invention, the workpiece is
The cold drawing process is performed with a resin film of uniform thickness applied, and the adhesion of the resin film allows for smooth drawing process, making it possible to obtain a highly accurate and high quality outer diameter part of the product. Become.

In addition, according to the cold drawing apparatus according to the present invention, a single die provided with an outer diameter adjustment section and a diameter reduction section can perform cold drawing on a workpiece provided with a resin film. This makes the cold drawing process smoother with simple equipment.
It becomes possible to obtain a product outer diameter portion with high precision and high quality.

[Example] FIG. 1 shows a cold drawing apparatus 10 according to an example of the present invention.
A sectional view showing a cold drawing apparatus 10 includes a die 11 and a plug 12.

The die 11 is a raw pipe 2 as a workpiece shown in FIG.
A tapered introduction section 11A for introducing 0 is provided on the most entry side. Furthermore, the die 11 is provided with an outer diameter adjustment part 11B for scraping off the thick part of the resin coating applied to the raw tube 20 on the exit side of the introduction part 11A. Further, the die 11 is provided with a diameter reducing part lIC for reducing the diameter of the element v20 on the exit side of the outer diameter adjusting part 11B.

That is, when the raw pipe 20 having a non-uniform lubricating film attached in the circumferential and longitudinal directions as shown in FIG. 2 is subjected to cold drawing by the die it and the plug 12,
First, the outer diameter of the raw pipe 20 is slightly reduced by the outer diameter adjusting part 11B, and the thick part of the lubricating film is scraped off. The product is successively subjected to outer diameter drawing and thinning processing to obtain wall thickness, resulting in product 20A.

Hereinafter, specific implementation results of the present invention will be explained. The material of the workpiece is 9% Cr steel, and the dimensions are 27.2 mm in outer diameter.
A wall thickness of 3.01 cm and a length of 800 h was used. First, as a pretreatment for drawing, the inner and outer surfaces were sandblasted to remove scale produced by hot rolling. After that, 30 to 40 pieces of the workpiece were bundled and immersed in an acrylic resin lubricating oil tank for 5 minutes, the liquid was drained, and the material was thoroughly dried in a drying tank at around 100°C. A strong lubricating film was formed on the material and used as a drawn material. The outer surface of this drawn material had a uniform film thickness in the longitudinal and circumferential directions. Such a workpiece is processed by the method of the present invention shown in Fig. 1 and the conventional method shown in Fig. 3.
Diameter 24.2mm, wall thickness 2.5W■, length 8029II
It was processed into a size of m. The dimensions of the die 11 used at this time were such that the diameter B of the outer diameter adjustment part 11B shown in Fig. 1 was 28.0 mm.
The outer diameter reduction ratio is set to approximately 4.4%, the diameter C of the subsequent diameter-reduced portion 11C is set to 24.2 mm, the outer diameter reduction ratio is set to 11%, and at the same time, the diameter of the plug 12 is set to 19%. .IB was applied between the two layers, and the thickness was reduced by 7%. On the other hand, with the conventional method, the diameter is 24.2 mm and the wall thickness is 2.5 m.
Processed into m. After that, the surface texture and dimensional accuracy of the outer diameter of the drawn pipe material were investigated. As a result, the results shown in Table 1 were obtained. As is clear from Table 1, it has been found that the present invention can significantly improve the defective rate due to poor surface texture and dimensional accuracy.

That is, according to the present invention, it is possible to significantly improve the roughness of the product outer surface and poor dimensional accuracy of the outer diameter, which are problems specific to dry film type lubricating oils, and to improve product yield and productivity. Is recognized.

In addition, in carrying out the present invention, in addition to performing outer diameter adjustment and diameter reduction processing simultaneously within one die, the die is divided into a die having only an outer diameter adjustment part and a die having only a diameter reduction part. The divided dice may be arranged and used in succession.

Table 1 [Effects of the Invention] As described above, the cold drawing method according to the present invention is a cold drawing method in which a workpiece coated with a dried resin film is cold drawn using a die. In this method, after the thick part of the resin film applied to the workpiece is scraped off, the diameter of the workpiece is reduced by the diameter-reducing part of the die. Therefore, the workpiece is drawn with a resin film of uniform thickness applied to it, making it possible to perform smooth drawing and obtain a highly accurate and high quality outer diameter part of the product. Become.

Further, the cold drawing apparatus according to the present invention includes a die for cold drawing a workpiece coated with a dried resin film. In addition to providing an outer diameter adjusting part for scraping off the thick film part of the resin film adhered to the workpiece, a diameter reducing part for reducing the diameter of the workpiece is provided on the exit side of the outer diameter adjusting part of the die. This is what I did. Therefore, a single die equipped with an outer diameter adjustment section and a diameter reduction section is used to perform cold drawing on the workpiece coated with a resin film, and the drawing process is facilitated by a simple device. It becomes possible to obtain a product outer diameter portion with high precision and high quality.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a processing device according to an embodiment of the present invention, Fig. 2 is a sectional view showing the distribution state of a resin film on the surface of a workpiece, and Fig. 3 is a sectional view showing a processing device according to a conventional example. FIG. 10... Processing device, 11... Dice, IIB...
Outer diameter adjustment part, itc... diameter reduction processing part, 20... raw pipe, 20A... product.

Claims (2)

[Claims] (1) A workpiece coated with a dried resin film,
In the cold drawing method in which cold drawing is performed using a die, the thick part of the resin film adhered to the workpiece is scraped off, and then the diameter of the workpiece is reduced using the diameter reduction section of the die. Characteristic cold drawing processing method. (2) In a cold drawing device having a die for cold drawing a workpiece coated with a dried resin film, the die is used to cold draw a workpiece coated with a dried resin film. A cold drawing device characterized in that an outer diameter adjusting section for scraping off a thick film part is provided, and a diameter reducing section for reducing the diameter of a workpiece is provided on the outlet side of the outer diameter adjusting section of the die. .