JP2726588B2 - Lubrication method for seamless steel pipe perforated plug - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in order to improve the life of a piercer piercing plug, which is a piercing and rolling mill for seamless steel pipes, conventionally, an alloy element is added to a plug material in a plug manufacturing process, or a shape having low resistance during piercing. And other measures were taken.

[0003]

However, even with the above-mentioned conventional means for improving the life, the steel pipe material is, for example, a high chromium steel (Cr%> 9%) having a high hot deformation resistance compared with a carbon steel. And the consumption of the perforated plug is severe,
There has been a problem that the life of the plug is significantly reduced, and eventually the tool unit consumption is deteriorated, the productivity is reduced, and further, a flaw in pipe production due to the damage of the plug occurs.

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

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and aims to significantly improve the life of a plug even when the steel pipe material is a material having a high hot deformation resistance such as high chromium steel. It is an object of the present invention to provide a method for lubricating a seamless steel pipe piercing plug, which can be performed.

[0006]

According to the present invention, a lubricating film is formed by applying a graphite-based lubricant to the surface of a perforated plug, and the perforated plug is formed into a billet in a state where the lubricating film is not wetted by roll cooling water. The object is achieved by a method for lubricating a seamless steel pipe piercing plug characterized by being bitten.

In order to prevent the lubricating film from being wet by the roll cooling water, the supply of the cooling water to the roll is stopped before the perforated plug on which the lubricating film is formed is engaged with the billet. You may do so.

Further, in order to prevent the lubricating film from being wet by the roll cooling water, a water-resistant film mutually insoluble in the graphite-based lubricant is formed outside the lubricating film. Is also good.

[0009]

According to the present invention, a lubricating film is formed by applying a graphite-based lubricant, which reduces an excessive coefficient of frictional resistance generated at the initial stage of perforation, to the surface of the perforated plug, and the lubricating film is formed by roll cooling water. The drilling plug is bitten into the billet so that it does not get wet, the lubrication effect is increased, and difficult-to-machine materials with high hot deformation resistance such as high chrome steel are drilled without impairing the roll cooling effect by the roll cooling water. Even in this case, it is possible to reduce the large friction at the initial stage of piercing and greatly improve the life of the piercing plug.

According to the second aspect of the present invention, in order to prevent the lubricating film from being wetted by the roll cooling water to be washed away or wet,
Since the supply of the roll cooling water is stopped, it is possible to reduce the large friction at the initial stage of the perforation without hindering the roll cooling.

According to the third aspect of the present invention, a water-resistant coating which is insoluble in a lubricating film made of a graphite-based lubricant is formed, and the perforated plug is bitten into the billet. Without losing the lubricating film,
The perforated plug can be bitten into the billet.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the apparatus for carrying out the method of the present invention shown in the drawings.

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

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

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

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

[0017]

[Table 1]

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

The film thickness 120 μ is a minimum value for maintaining a predetermined lubricating ability, and 180 μ is an upper limit value at which natural drying can be performed by heat of the perforated plug 10 during a waiting time until the billet is caught. .

Therefore, in the case of forced drying, the maximum value of the 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 (position 3). The supply of the cooling water from the cooling water nozzle 26 is stopped.

When the perforated plug 10 bites into the billet 24, it is assumed that the detection value from the load cell 28 for detecting the rolling load of the rolling roll 22 is equal to or more than a certain value. The detection signal of the load cell 28 is output to the control device 32,
When the rolling load is equal to or more than a certain value, the control device 32
The valve 34 is opened to supply the cooling water to the cooling nozzle 26.

After the piercing is completed, the piercing plug 10 is extracted and returned to the position 1 where the surface temperature of the piercing plug 10 is measured by the thermometer 12. Thereafter, the surface temperature of the piercing plug 10 is measured, the lubricating film is formed, and the lubricating circuit for biting is formed. Run the configuration.

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 outside the lubricating film 20 formed by applying a graphite-based lubricant (FIG. 3).
reference).

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

Here, the 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 outside of the lubricating film 20 is covered with the water-resistant coating 30, the supply of the cooling water is performed before the perforated plug 10 is bitten into the billet 24 as in the first embodiment. No need to stop.

According to the experiment of the present inventor, the life of the perforated plug in the case of using the lubricating method of the first embodiment and the second embodiment is longer than that in the case where the lubricating film or the waterproof film is not provided. As shown in Table 3, it was 1.7 to 2.5 times.

[0032]

[Table 3]

In the above embodiment, the water-resistant coating is formed of polyaluminum chloride. However, the present invention is not limited to this. If necessary, a graphite-based lubricant may be used. Any material may be used as long as it is made of a material that does not lose water even after being washed away by the cooling water.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an apparatus for performing 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 sectional view showing a perforated plug on which a lubricating film is formed by the method of the present invention.

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

FIG. 4 shows 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]

 DESCRIPTION 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)

(57) [Claims] The present invention is characterized in that a graphite-based lubricant is applied to the surface of a perforated plug to form a lubricating film, and the perforated plug is bitten into a billet in a state where the lubricating film is not wetted by roll cooling water. Lubrication method for seamless steel pipe perforated plugs. 2. A seamless steel pipe piercing plug according to claim 1, wherein the supply of cooling water to said roll is stopped before said piercing plug on which said lubricating film is formed is bitten by said billet. Lubrication method. 3. The method according to claim 1, wherein:
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.