JPS60247410A - Drawing method of steel pipe - Google Patents

Abstract

PURPOSE:To prevent the seizure occurring in the deterioration arising from the cyclic use of a lubricating oil by coating the high-viscosity lubricating oil having substantially no fluidity to the required section on the pointing end side of the inside surface of a blank pipe prior to drawing of the blank pipe then drawing the pipe by using a plug while supplying continuously the lubricating oil to the inside and outside surfaces of the blank pipe. CONSTITUTION:The high-viscosity lubricating oil 8 is coated to the pointing part 5 on the inside surface of the blank pipe 1 as shown in the figure (p) prior to drawing. The blank pipe 1 is then drawn by a die 3 as shown in the figure (q). Since the oil 8 is of a high viscosity, the outflow of the oil coated on the upper side of the pipe 1 to the lower side and the consequent lack of the oil in the upper side part are obviated and the pipe is drawn satisfactorily while the high resistance to seizure is maintained. The oil is supplied continuously to the inside surface of the pipe, as shown by an arrow (b), through a mandrel 4 from an oil tank as shown in the figure (r) in succession to the end of drawing the pointing part 5 of the pipe 1 and the pipe is drawn while the inside surface thereof is lubricated. The crop 9 at the pipe end is discarded as shown in the figure (s) upon ending of the drawing. The oil 8 is fully removed together with the crop 9 to the outside of the system and therefore the inside surface of the product pipe is surely prevented from staining by the residual oil.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a low-cost, high-productivity cold drawing method for steel pipes by direct oil-lubricated drawing.

<Prior Art> In the case of steel pipes, the main lubrication treatment during cold drawing of pipes is chemical coating treatment, and when oil lubrication is used, pre-immersion or pre-coating is usually used. However, although chemical coating treatment enables drawing with a high processing load (drawing degree and speed), there are problems in terms of chemical costs, man-hours, and environmental pollution countermeasures, and pre-dipping or pre-applying oil lubrication is not suitable. In addition to problems in terms of basic unit and man-hours, there is also the drawback that it is impossible to set a high processing load like chemical conversion treatment.

On the other hand, a so-called direct oil lubrication method is known, in which lubricating oil is poured onto the snow as the drawing progresses.This method solves the above problems and reduces the cost of the drawing process. It can be said that it is effective.

However, in the past, ■ the performance of the lubricating oil itself was not able to withstand high processing loads comparable to that of chemical conversion coatings, and ■ it was necessary to establish a system for its cyclical use in terms of oil costs.
■In practice, application to steel pipes has been refrained from due to concerns that raffle residue on the inner surface of the pipe may adversely affect the quality of the finished product.

Recently, a high-performance lubricating oil has been developed that solves the problem (1) above, and with this, all that is needed to realize the application of the direct oil lubrication method to steel pipes is to address the problems (2) and (3) above.

However, regarding (1), a simple circulation system in which lubricating oil is continuously supplied from an oil storage tank to the outer surface of the tube just before it enters the die and the inner surface of the tube just before it hits the plug, and then returns all the oil after the lubrication process to the tank is not possible. As the circulation of oil progresses, scales and rust on the inner and outer surfaces of the tube accumulate in the oil, deteriorating the oil and making it more likely that tools will seize.This is especially noticeable on the inner surface of the tube. There is a problem in that it is impossible to draw with a processing load as high as chemical conversion treatment.

Regarding item (2) above, in direct oil-lubricated drawing, it is difficult to lubricate the inner surface of the pipe near the end, so it is necessary to apply oil in advance, but this oil remains even after the drawing process. This is a major problem because it flows toward the other end of the tube and becomes ashes during the subsequent heat treatment of the finished product, causing stains on the inner surface. As a countermeasure to this problem, methods have been considered to reduce the amount of oil supplied as much as possible by delaying the oil supply timing as much as possible and starting oil supply just before the drawing process, so as to prevent residual oil from forming. However, this method leaves unsolved the problem of seizures due to lack of oil supply associated with buffiness in the operation of the electro-mechanical equipment.

<Objective of the Invention> The present invention solves the above-mentioned drawbacks of the conventional method and eliminates seizure caused by deterioration due to the cyclic use of lubricating oil. The purpose of this invention is to provide a method for drawing steel pipes by direct oil lubrication drawing, which is intended to prevent contamination of the inner surface of the product due to the above.

<Structure of the Invention> In other words, the present invention provides the following features: (1) When drawing using a plug is performed while continuously supplying lubricating oil to the inner and outer surfaces of the raw pipe, the opening on the inner surface of the raw pipe is substantially located at a required portion on the end side prior to drawing. mW drawing method characterized by applying non-flowable high viscosity lubricating oil and then drawing on it; ■ When performing plug drawing while continuously supplying lubricating oil to the inner and outer surfaces of the raw pipe, Prior to drawing, a high viscosity lubricating oil with virtually no fluidity is applied to the necessary areas on the end of the inner surface of the raw pipe to begin drawing. The gist of the present invention is a method for drawing a W4 tube, which is characterized in that it is used cyclically while being subjected to a removal process.

Example Hereinafter, the method of the present invention will be specifically explained based on the drawings.

FIG. 1 is an explanatory diagram showing a specific example of the drawing method of the present invention. - In the figure, (1) is the raw pipe, (2) is the die, (3) is the plug, (4) is the mandrel that supports the plug (3), (5) is the mouth of the raw pipe, (6) is an oil tank for the outside of the pipe, and (7) is an oil tank for the inside of the pipe.

The drawing of element g(1) is carried out by continuously supplying lubricating oil from the tank (6) to the outer surface of the tube and from the tank (7) to the inner surface of the tube through the mandrel/l' (41).
), the spout is performed by pulling part (5) in the direction of arrow (a) and passing the raw tube (1) through a die <2). The figure shows a state in which the raw pipe (1) is passing through the die (2) and being drawn.

In the method of the present invention, prior to drawing, a high viscosity lubricant with substantially no fluidity (for example, a lubricant with a viscosity of 1000 to 80'000 at 40° C.
The first feature is that it coats StO (StO).

That is, prior to drawing, high viscosity lubricating oil (8) is applied to the opening (5) on the inner surface of the raw pipe (1) as shown in FIG. 2(A). Next, roll the dice (3) as shown in Figure 2 (Stem).
However, since the lubricating oil (8) has a high viscosity, the lubricating oil (8) applied to the upper side of the tube (1) will flow downward and the upper part will not be starved of oil, making it seizable. The properties are sufficiently maintained and good drawing is performed. After the drawing of the flJ element tube (1) is completed, as shown in FIG. As shown by the arrow (2), oil is continuously supplied to the inner surface of the tube to lubricate it, and drawing is performed. ) remains completely coated even after drawing as shown in the figure, and the opening remains in the portion (5), and does not flow toward the other end of the tube as in the conventional example.

Then, as shown in FIG. 2), after the drawing is completed, the tube end crop (9) is truncated along the line ff, but the entire amount of the high viscosity lubricating oil (8) is discarded from the truncated crop ( 9) Since it can be removed from the system together with the crop (9), the method of the present invention ensures that the occurrence of contamination on the inner surface of the product tube due to residual oil that occurs in conventional methods is avoided. It can be prevented.

Next, the second feature of the method of the present invention is that the lubricating oil that is continuously supplied to the inner and outer surfaces of the raw pipe (1) is circulated and used while removing iron from the oil. In this case, the lubricating oil that is continuously supplied to the inner and outer surfaces of the tube is a low-viscosity lubricating oil (for example, a viscosity of 40 tC, 200 to 1000 C3t), as in the conventional method.
O items] are used. The lubricating oil circulation system according to the present invention will be explained below.

In FIG. 1, the head is a pipe for supplying lubricating oil from the pipe outer surface oil tank (6) to the vicinity of the outer surface of the raw pipe (1) immediately before entering the die (2), and is equipped with a pump 0η in the middle. α is a pipe connecting the tube inner surface tank (7) and the rear end of the mandrel (4), and is equipped with a pump a3 in the middle. The mandrel /l/(4) has a hollow structure (indicated by a broken line) so as to be able to feed oil for the inner surface of the tube. α 弔 is an oil spray nozzle installed at the tip of the mandrel (4) immediately adjacent to the plug (3), and there are many nozzles in the circumferential direction of the outer periphery so that oil can be sprayed evenly over the entire circumference of the inner surface of the tube. A hole (not shown) is provided. αO is a recovery device that recovers all the lubricated oil continuously supplied to the inner and outer surfaces of the tube, and is provided below the outer surface of the tube. 0Q is an iron removal device for removing iron from oil, and is provided in the middle of a pipe αη connecting the recovery device α0 and the pipe outer surface oil tank (6). Q81 u The piping that connects the V external oil tank (6) and the internal pipe oil tank (7) is equipped with a pump in the middle.

Oil circulation in direct oil lubrication drawing by the system configured as described above is performed as follows. In other words, pass the pipe Q1 from the tank (6)! 7'tf (1) All the lubricating oil continuously supplied to the outer surface of the pipe is transmitted along the outer surface of the pipe and collected by the collecting device αG as appropriate. Also, new oil (indicated by A) is supplied to the tank (7), and this new oil passes through the piping a mandrel (4) from the oil spray nozzle/I/a to the pipe (1).
The entire oil after lubrication exits from the rear end of the pipe (1) as shown by arrow (Q), travels along the outer surface of the pipe, and is appropriately collected by a collection device αQ.

All the recovered oil passes through the pipe αη to the iron removal device α
After the iron content in the oil is removed, the oil is returned to the outside oil tank (6) via the pipe αη, where it is reused. In addition, in the circulation system of the present invention, piping is arranged so that when the tank (6) becomes full, for example, the oil in the tank (6) can be transferred to the tank (7) by activating the pump Q as appropriate. (to) is provided.

In this way, by using the method of the present invention to recirculate the lubricating oil that is continuously supplied during drawing while removing the iron content in the oil, it is possible to prevent the build-up of scales, rust, etc. on the inner and outer surfaces of the tube, and the deterioration of the oil, unlike in the conventional method. This effectively suppresses seizure of the tool material due to oil deterioration.

The reason why seizing can be prevented by removing the iron content from the lubricating oil used in circulation as described above is as shown by the results of the following tests.

That is, the present inventors conducted an SRv test under the following conditions in order to investigate the influence of iron in lubricating oil on seizure.

Conditions Material of test material: 5UJ-2 Test load = 100 to 60ON (N is Newton) Test temperature and time: 1oot:, IO minute vibration frequency: 50Hz The test results show that the resistance to seizure is as shown by curve υ) in Figure 3. The relationship between iron content and load was obtained.

As shown in the figure, there was no occurrence of seizure in the area surrounded by the curve (b) (indicated by diagonal lines), but seizure occurred in the area outside of the area (f).・In other words, as shown in the above test results, seizing during drawing can be effectively suppressed by reducing the iron content by removing the iron content in the oil. This makes it possible to increase the processing load to 200 to 25 ON, which corresponds to the number of chemical conversion coating treatments.

Although not specified in the method of the present invention, in drawing under conditions of high processing load, the die (2) shown in Fig. 1 is used.
and Ti-C or Ti-C- on the surface of the plug (3).
Coating with a hardened film such as N is recommended because it is effective in preventing tool seizure.

<Effects of the Invention> The method for drawing W4 pipes of the present invention described above uses continuously supplied lubricating oil while removing iron in the oil during direct oil lubrication drawing, and also uses a continuous supply of lubricating oil in the raw pipe prior to drawing. Face guttering uses a method of applying high viscosity lubricating oil to the required parts on the end side and drawing, so compared to conventional methods, it is possible to perform high machining loads or continuous drawing for a long period of time without burning. The spout has the effect of preventing the inner surface of the product from becoming contaminated due to oil pre-applied to the edge. Specific examples comparing the method of the present invention and the conventional method with respect to these points are as follows.

Example 1 Outer diameter 42.7 head f, wall thickness 5.3 m, material 5
A 20C raw pipe is used, the drawing degree is 36%, and low viscosity lubricating oil (viscosity of 200 to 100% at 40°C) is applied to the inner and outer surfaces of the pipe.
A drawing test was conducted using the method of the present invention and the conventional method under the condition that drawing using a plug was performed while continuously supplying 0C8t).
We conducted the investigations shown in (a) and (b) below.

■ Prior to drawing, high viscosity lubricating oil (
Viscosity of 1000 to B 000 Cst at 40℃)
In the conventional method, drawing is carried out using the same low viscosity lubricating oil as in the continuous supply mentioned above, and after the drawing is completed, the pipe end crop is cut off according to the usual method, and then the product is heat treated to avoid internal contamination due to carbonization, etc. investigated. As a result, in all of the conventional examples, a lot of inner surface stains such as carbonization caused by the residual oil from the above-mentioned pre-applying were observed on the inner surface of the product, but in contrast, in the inventive example, the pre-applying oil was discarded together with the pipe end crop. Since there was no residual oil, no stains were observed on the inner surface of the product.

(b) In the drawing under the above conditions, in the conventional example in which the iron content in the lubricating oil used for circulation was not removed, the die plug etc. were seized during the 1.6 ton processing after the start of drawing, and drawing was not completed. It's now possible. On the other hand, the method of the present invention, in which iron content is removed from lubricating oil used in circulation, was able to perform continuous drawing for a long period of time without seizure. It was shown that long-term seizure resistance was achieved.

Example 2 Using a raw pipe with the same material dimensions as in Example 1 above, using the same method of oil lubrication and plug use, various drawings were carried out by the method of the present invention and the conventional method, with various drawing degrees, and We investigated the limits of each drawing degree without the use of As a result, in the conventional example, the degree of drawing was 40%.
If it exceeds 40%, the tool will seize, so the above 40% was the limit of the drawing degree. On the other hand, in the example of the present invention, it is possible to draw without burning even if the drawing degree is 43% of the number of chemical conversion coatings, and the method of the present invention can obtain a processing load equal to the number of chemical conversion coatings. It was shown that

Therefore, the steel pipe drawing method of the present invention exhibits remarkable effects in reducing drawing conuts and improving work efficiency.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram and cross-sectional view of an example of an apparatus for carrying out the method of the present invention, and Figures 2 (a) to 2) show high-viscosity lubricant applied to the required portions of the end of the inner surface of the raw pipe according to the present invention. FIG. 3, which is an explanatory diagram regarding the behavior of oil, is a graph showing the relationship between the iron content in the lubricating oil and the load in the SRV test. 1: Raw pipe, 2: Dice, 3 Nibufugu, 4: Mandrel,
5: Mouth part, 6.7: Oil tank, 8: High viscosity lubricating oil,
9: Pipe end crop, 10.12.17.18: Piping,
11, 13, 19: Pump, 14: Oil spray nozzle, 15
: Recovery device, 16: Iron removal device

Claims (2)

[Claims] (1) When drawing using a plug while continuously supplying lubricating oil to the inner and outer surfaces of the raw pipe, prior to drawing, the opening on the inner surface of the raw pipe is coated with high-viscosity lubricant that is inherently non-fluid at the required parts on the end side. A method for drawing steel pipes, which is characterized by applying oil and then drawing it. (2) When drawing using a plug while continuously supplying lubricating oil to the inner and outer surfaces of the raw tube, prior to drawing, the opening on the inner surface of the raw tube is lubricated with high viscosity lubrication on the required end side. A method for drawing a steel pipe, characterized in that drawing is started by applying oil, and continuous lubrication during drawing is carried out by circulating and using lubricating oil while carrying out treatment to remove iron in the oil.