JPH05138213A - Lubricating method for piercing plug for seamless steel pipe - Google Patents

Abstract

PURPOSE:To greatly improve the life of a piercing plug even with a material having high hot deformation resistance by applying a lubricant on the surface of the plug and biting the plug into a billet without wetting the formed lubricating film with roll cooling water. CONSTITUTION:The surface temp. of the piercing plug 10 for producing a seamless steel pipe is measured in a position 1 and the temp. is controlled to 80 to 180 deg.C in a cooling tank 14. While the plug 10 is rotated by turning rollers 16 in a position 2, the graphite lubricant is applied to the plug by a spraying device 18 and the film thickness thereof is adjusted to 120 to 180mum. The cooling water from nozzles 26 is stopped at the time of biting the plug to the billet 24 between rolling rolls 22 and 22 or after the water resistant film is applied on the graphite lubricating film, the plug is carried to a position 3 thereby the wetting of the lubricating film with the water is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for lubricating a seamless steel pipe perforation plug, and more particularly to a lubrication method for significantly improving the life of the perforation plug.

[0002]

2. Description of the Related Art In order to improve the life of a piercer piercing plug, which is a piercing and rolling machine for seamless steel pipes, conventionally, alloy elements have been added to the plug material during the plug manufacturing process, or a shape with less resistance during piercing And other measures were taken.

[0003]

However, even with the above-described conventional life-improving means, in the case where the steel pipe material is high chromium steel (Cr%> 9%) having high hot deformation resistance, it is compared with the case of carbon steel. And the consumption of the piercing plug is severe,
There has been a problem that the life of the plug is significantly shortened, the tool unit consumption is deteriorated, the productivity is lowered, and a pipe manufacturing defect is caused due to the damage of the plug.

For example, as shown in FIG. 4, when the life of the piercing plug is 100 when the steel pipe material is carbon steel,
It can be seen that in the case of high chromium steel or austenitic stainless steel, the plug life is remarkably reduced.

The present invention has been made in view of the above-mentioned problems of the prior art. Even if the steel pipe material is a material having a high resistance to hot deformation such as high chromium steel, the life of the plug is significantly improved. It is an object of the present invention to provide a method for lubricating a seamless steel pipe perforated plug, which is capable of

[0006]

According to the present invention, a graphite-based lubricant is applied to the surface of a perforated plug to form a lubricating film, and the perforated plug is formed into a billet in a state where the lubricating film is not wet with roll cooling water. The above object is achieved by a method of lubricating a seamless steel pipe perforation plug which is characterized in that it is bitten.

In order to prevent the lubricating film from getting wet with the roll cooling water, the cooling water supply to the roll is stopped before the billet is caught in the perforated plug having the lubricating film formed thereon. You may do it.

Further, in order to prevent the lubricating film from getting wet with the roll cooling water, a water resistant film which is mutually insoluble in the graphite lubricant is formed on the outside of the lubricating film. Good.

[0009]

According to the present invention, a graphite-based lubricant that reduces the excessive frictional resistance coefficient generated at the initial stage of perforation is applied to the surface of the perforation plug to form a lubricating film, and the lubricating film is formed by roll cooling water. Prevents water from getting wet and bites the piercing plug into the billet to enhance the lubrication effect and to perforate difficult-to-machine materials such as high chrome steel with high resistance to hot deformation without impairing the roll cooling effect of the roll cooling water. Even in such a case, the large friction at the initial stage of drilling can be reduced, and the life of the drill plug can be greatly improved.

According to the second aspect of the present invention, in order to prevent the lubricating film from being washed away by the roll cooling water so as not to be washed out or wet, the piercing plug is inserted before the billet is engaged.
Since the supply of the roll cooling water is stopped, it is possible to reduce the large friction at the initial stage of perforation without affecting the roll cooling.

According to the third aspect of the present invention, since the water resistant coating which is insoluble in the lubricating film made of the graphite-based lubricant is formed and the hole plug is engaged with the billet, the supply of the roll cooling water is stopped. To prevent the lubrication film from flowing away,
The piercing plug can be engaged in the billet.

[0012]

Embodiments of the present invention will now be described in detail with reference to the apparatus for carrying out the method of the present invention shown in the drawings.

First, at the position 1, the surface temperature of the perforated plug 10 which is at a high temperature is measured by the thermometer 12.

Next, based on this measurement result, the cooling tank 14
By controlling the cooling time, the surface temperature of the perforated plug 10 is controlled to 80 ° C to 180 ° C.

Perforated plug 10 cooled to the above temperature
Is transferred onto the turning roller 16 at the position 2, where the graphite-based lubricant is applied by the spray device 18 while being rotated by the turning roller 16.

The graphite-based lubricant is composed of, for example, the components shown in Table 1 below.

[0017]

[Table 1]

At this time, the thickness of the graphite-based lubricant is 120 μm.
˜180 μ.

The film thickness of 120 μ is the minimum value for maintaining a predetermined lubricating ability, and 180 μ is the upper limit value that can be naturally dried by the heat of the perforated plug 10 during the waiting time until the billet is caught. ..

Therefore, in the case of forced drying, the maximum value of film thickness is further increased.

Next, the perforated plug 10 on which the lubricating film 20 made of a graphite-based lubricant is formed is bitten into the billet 24 between the rolling rolls 22 and 22 (position 3), but until this biting is completed, The supply of cooling water from the cooling water nozzle 26 is stopped.

The biting of the piercing plug 10 into the billet 24 is performed when the detection value from the load cell 28 for detecting the rolling load of the rolling roll 22 becomes a certain value or more. The detection signal of the load cell 28 is output to the controller 32,
The control device 32, when the rolling load becomes a certain value or more,
The valve 34 is opened to supply the roll cooling water to the cooling nozzle 26.

After completion of the perforation, the perforation plug 10 is pulled out and returned to the position 1 where the surface temperature of the perforation plug 10 is measured by the thermometer 12, and thereafter, the surface temperature of the perforation plug is measured, a lubricating film is formed, and a lubricating circulation for biting is performed. Run the application.

Next, a second embodiment of the present invention will be described.

In this embodiment, a water resistant coating 30 made of polyaluminum chloride is formed on the outside of the lubricating film 20 formed by applying a graphite type lubricant (FIG. 3).
reference).

More specifically, when the lubricating film 20 is in a non-dried state, polyaluminum chloride is applied onto the lubricating film 20 and the temperature (120-1) of the perforated plug 10 itself is maintained.
The strong water resistant coating 30 is formed at 40 ° C.).
Polyaluminum chloride may be applied after the lubricating film 20 has dried, but the waiting time increases and the efficiency decreases.

Here, the film thickness of the water resistant coating 30 is determined by the drying time (18 to 24 seconds) and the temperature of the perforated plug 10.

Other conditions are as shown in Table 2.

[0029]

[Table 2]

In this embodiment, since the outer surface of the lubricating film 20 is covered with the water resistant coating 30, the cooling water is supplied before the biting of the perforated plug 10 into the billet 24, as in the first embodiment. No need to stop.

According to the experiments conducted by the present inventor, the life of the piercing plugs obtained by the lubrication methods of the first and second embodiments is longer than that in the case where no lubricating film or water resistant film is provided. As shown in Table 3, it became 1.7 to 2.5 times.

[0032]

[Table 3]

In the above examples, the water resistant coating is formed of polyaluminum chloride, but the present invention is not limited to this, and if necessary, a graphite-based lubricant applied in advance. Any material may be used as long as it is made of a material that is not washed away with water and is not washed away by cooling water.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an apparatus for carrying out a method for lubricating a seamless steel pipe perforated plug according to the present invention and a state of lubrication circulation.

FIG. 2 is an enlarged cross-sectional view showing a perforated plug having a lubricating film formed by the method of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a perforated plug having a lubricating film and a water resistant film formed by a method according to a second embodiment of the present invention.

FIG. 4 illustrates carbon steel in a conventional perforated plug.
It is a diagram which shows the plug life with respect to various steel pipes when it is set to 00.

[Explanation of symbols]

 10 ... Perforated plug, 12 ... Thermometer, 18 ... Spray device, 20 ... Lubrication film, 24 ... Billet, 26 ... Cooling water nozzle, 30 ... Water resistant coating.

Claims (3)

[Claims] 1. A graphite-based lubricant is applied to the surface of a perforated plug to form a lubricating film, and the perforated plug is engaged with a billet in a state where the lubricating film is not wet with roll cooling water. Lubrication method for seamless steel pipe drilling plugs. 2. The seamless steel pipe piercing plug according to claim 1, wherein the supply of the cooling water to the roll is stopped before the billet is caught in the piercing plug having the lubricating film formed thereon. Lubrication method. 3. The outer surface of the lubricating film according to claim 1,
A method for lubricating a seamless steel pipe perforated plug, comprising forming a water resistant coating that is mutually insoluble in the graphite-based lubricant.