JP2553985B2 - Rolling method and equipment for seamless steel pipe in mandrel mill - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling a seamless steel pipe in a mandrel mill and its equipment.

[0002]

2. Description of the Related Art In a mandrel mill, a raw pipe having a mandrel bar inserted therein is charged into rolling rolls of several stands to roll a seamless steel pipe. Depending on whether the mandrel bar is restrained or not, the restrained type, semi-floating type, and full floating type are known. In either method, generally, a plurality of mandrel bars are prepared for the same rolling chance, the mandrel bar is replaced every time one raw tube is rolled, and the raw tube is sequentially rolled by the next mandrel bar. I am trying. In this system, the mandrel bar once used for rolling is sequentially returned through the circulation line around the mandrel mill and is used for the next rolling.

[0003]

In the above-mentioned mandrel bar circulation system, a space for providing a circulation line is required, the equipment cost is increased, and more time is required to replace the mandrel bar. There's a problem.

Under the circumstances, it is impossible to continuously use the same mandrel bar and continuously roll many element pipes one after another. However,
The following continuous use of the same mandrel bar in the same rolling change has the following problems. When the same mandrel bar is continuously used, due to the positional relationship of the mandrel bar corresponding to the arrangement of the rolling rolls in the mandrel mill, the rolling stress becomes large at the mandrel bar portion corresponding to the hole bottom of the rolling roll,
Since the rolling stress is small at the part of the mandrel bar that corresponds to the roll opening of the rolling roll, uneven wear occurs in the circumferential direction of the mandrel bar, which causes load fluctuation during rolling, and in extreme cases. Becomes unrollable. Further, when the mandrel bar is turned after use, it may cause a reduction in the mandrel bar unit due to uneven wear in the circumferential direction of the mandrel bar. Furthermore, after use, in the cooling process of the mandrel bar, temperature unevenness due to uneven heat is generated in the circumferential direction, and in a remarkable case, the mandrel bar is bent. This bend needs to be corrected after the line is turned off. For this reason, the same mandrel bar
It is not possible to continuously roll the next tube using
Not not.

The present invention solves these problems described above, and even when the mandrel bar is continuously used continuously, the mandrel bar is not unevenly worn and the surface temperature of the mandrel bar is not uneven. The purpose of the present invention is to provide a method for rolling seamless steel pipe and a facility therefor.

[0006]

In order to achieve the above object, the present invention provides a method for rolling a seamless steel pipe in a mandrel mill, in which a mandrel bar is rotated at its supporting end on a rolling line on the mandrel mill entry side. The mandrel bar is supported so that the mandrel bar is fixed at the supporting end, the mandrel bar is rotated in the circumferential direction after rolling the blank tube, and the position of the mandrel bar with respect to the rolling roll is changed to the next element. A method for rolling seamless steel pipe in a mandrel mill characterized by rolling the pipe continuously , and a turning roller that horizontally supports the lower part of the mandrel bar supported by the retainer on the rolling line on the mandrel mill entrance side. It is composed of movably provided equipment for carrying out the above-described rolling method for a seamless steel pipe. The rotation of the mandrel bar in the circumferential direction will be described. In the rolling roll of one stand of the mandrel mill,
When the rolling rolls are arranged horizontally, the rolling stress is large at the mandrel bar portion corresponding to the hole bottom of the rolling roll, and the rolling stress is small at the mandrel bar portion corresponding to the roll opening of the rolling roll. Become. That is, the rolling pressure is large in the upper and lower parts of the mandrel bar, and small in the left and right parts. Then, in the next stand, since the rolling rolls are arranged vertically, the rolling pressure becomes large at the left and right portions of the mandrel bar and becomes small at the upper and lower portions. In consideration of the magnitude of such rolling pressure, in the mandrel bar, the mandrel bar is configured so that the part where the rolling pressure becomes large does not become the part where the rolling pressure becomes large even in the next rolling of the blank pipe. The mandrel bar is rotated by appropriately selecting the position on the circumference of, and the position of the mandrel bar is changed. Simply, from the arrangement of the rolling rolls of all stands, in the vertical and horizontal parts where the rolling pressure becomes large,
The mandrel bar may be rotated by 45 ° in order, avoiding the repositioning of the mandrel bar during the next rolling of the tube. This rotation may be carried out for each individual pipe, but depending on the rolling load condition, some rolling may be carried out for the next next raw pipe. Since the magnitude of the rolling pressure affects the surface temperature of the circumference of the mandrel bar, the rotation of the mandrel bar helps to make the surface temperature of the mandrel bar uniform. Starting
Provide a turning roller so that it can move up and down
After releasing the mandrel bar after rolling the raw tube
Then, when the mandrel bar is set in a freely rotatable state,
Fully contact the turning roller with the mandrel bar
To smooth the rotation of the mandrel bar.
It

[0007]

According to the present invention, in rolling a seamless steel pipe in a mandrel mill, the mandrel bar is rotatably supported at its supporting end, and the mandrel bar is appropriately rotated in the circumferential direction on the mandrel mill entrance side to prevent the rolling roll from rolling. The position of the mandrel bar is changed to avoid uneven wear of the mandrel bar, the temperature of the mandrel bar is made uniform, and the shape is maintained normally.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a retainer 3 that supports the mandrel bar 2 is installed on the entrance side of the mandrel mill 1. The retainer 3 mounts and supports the mandrel bar 2 carried into the mandrel bar charging floor 4. The retainer 3 is moved forward in the direction of the mandrel mill 1 on the rolling line by the forward drive device, the raw pipe from the intermediate transfer bed 5 is inserted into the mandrel bar 2, and the raw pipe and the mandrel bar 2 are moved.
It is charged into the rolling roll. Mandrel bar 2 in the present invention
Restraint method or semi-floating method.

In FIG. 2, in this example, turning rollers 6 are provided at two positions along the longitudinal direction of the mandrel bar 2. Rear end of mandrel bar 2 is retainer 3
It is fixed by the clamp 7. The clamp 7 operates when the mandrel bar 2 is operated, and the operation is released when the mandrel bar 2 is rotated.

FIG. 3 is a cross section taken along the line AA (cross section BB) of FIG.
And the turning roller 6 has two rollers 6 on the left and right.
a. Although the roller 6a in this example is provided with a rotation drive mechanism, it may be freely rotated and a rotation device may be separately provided in the clamp 7 portion. The turning roller 6 includes a vertical movement mechanism 8. In addition to such an aspect, a skew roll can be used for the rotation of the mandrel bar. Therefore, in the present invention, the turning roller is used to include a skew roll. Turning roller 6 up
By providing the lowering mechanism 8, the mandrel bar 2 is manufactured.
In the state where the operation of the clamp 7 is released at work
Of the turning roller 6 to the mandrel bar 2
Ensures sufficient contact, smooth rotation of the mandrel bar 2, and
Assure. This facilitates the transition to the next rolling of the blank tube.
Speed up and improve workability.

FIG. 4 shows the mechanism of the clamp 7. The mandrel bar 2 is pressed and clamped by the hydraulic cylinder 9 and the piston 10 and mounted on the retainer 3. The mandrel bar 2 is clamped when the mandrel bar 2 is operated, and the clamp is released when the mandrel bar 2 is rotationally driven.

Rolling was carried out as follows using the seamless steel pipe rolling equipment in the above-mentioned mandrel mill. Diameter 132
Using a four-stand mandrel mill, 1000 pipes each having a diameter of 120 mm and a thickness of 4.1 mm were rolled, and a total of 160 tons of steel pipes having a diameter of 120 mm and a thickness of 4.1 mm were rolled. At that time, the mandrel mill bar 2 was rotated by 45 ° for each tube. Therefore, the temperature difference of the surface circumference of the mandrel bar 2 was within 50 ° C. As a result, uneven wear did not occur on the surface of the mandrel 2, and deformation such as bending did not occur.

FIG. 5 shows a mode in which the skew roll 6 is used as the turning roller. Two skew rolls 6 are installed so as to intersect the axis of the mandrel bar 2 at an acute angle and an obtuse angle at the other. Both of them rotate in opposite directions to apply a rotational force to the mandrel bar 2 and the axial forces cancel each other out.

FIG. 6 shows a mode in which the turning roller 6 is freely rotated and the clamp 7 is rotated by the electric motor 14 via the gear mechanism 13.

[0015]

The present invention is configured as described above.
The surface temperature of the mandrel bar is uniformized, uneven wear does not occur, and the basic unit is improved. Further, since the uneven heat distribution on the surface of the mandrel bar is small, there is no unevenness in the amount of the lubricant applied to the surface of the mandrel bar, and the amount of the lubricant applied is uniform on the peripheral surface of the mandrel bar . rolling
Sometimes, on the surface of the mandrel bar, the lubricant
Being held in a homogenized state means that the mandrel
Identical mandrel combined with uniform bar surface temperature
Uneven wear of mandrel bar surface during continuous bar use
Can be effectively prevented. Thus, the same mandrel bar can be continuously used, and the raw tube can be continuously and efficiently rolled.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of seamless steel pipe rolling equipment in a mandrel mill according to the present invention.

FIG. 2 is a view showing that the mandrel bar is supported by a turning roller.

3 is a view showing a cross section taken along line AA (cross section taken along line BB) of FIG.

FIG. 4 is a diagram showing details of the clamp of the mandrel bar.

FIG. 5 is a diagram showing a mode in which a skew roll is used as a turning roller.

FIG. 6 is a diagram showing an aspect in which the clamp includes a rotation device.

[Explanation of symbols]

 1 Mandrel Mill 2 Mandrel Bar 3 Retainer 4 Mandrel Bar Charging Floor 5 Transfer Floor 6 Turning Roller 7 Clamp 8 Vertical Movement Mechanism 9 Hydraulic Cylinder 10 Piston 11 Lubricant Applying Device 12 Extractor 13 Gear Mechanism 14 Electric Motor

Claims (2)

(57) [Claims] 1. In a method for rolling a seamless steel pipe in a mandrel mill, a mandrel bar is rotatably supported at its supporting end on a rolling line on the mandrel mill entrance side, and the mandrel mive is fixed at the supporting end. After rolling the tube, the mandrel bar is rotated in the circumferential direction to change the position of the mandrel bar with respect to the rolling roll to continuously roll the next tube, and the seam in the mandrel mill. Rolling method for steelless pipe. 2. The rolling of a seamless steel pipe in a mandrel mill according to claim 1, wherein a turning roller for horizontally supporting the lower part of the mandrel bar supported by the retainer is provided on the rolling line on the entry side of the mandrel mill so as to be vertically movable. Equipment for carrying out the method.