JPH0159042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tube shape control method using a reeler.

FIG. 1 is a process diagram showing the manufacturing process of a seamless steel pipe using a general plug mill method. The material heated in the heating furnace 1 is pierced and rolled in the piercer 2,
The elongator 3 performs tube expansion and elongation rolling, the plug mill 4 rolls the tube to a thickness almost equal to the product wall thickness, the reelers 5A and 5B polish the inner and outer surfaces, and the sizer 6 finishes the tube to a predetermined outer diameter to produce the final product. becomes. Note that, in order to balance the tube manufacturing efficiency of each rolling mill, two reels 5A and 5B are generally arranged in parallel for each of the piercer 2, elongator 3, plug 4, and sizer 6.

The reels 5A and 5B need to ensure a stable rolling condition as final finishing mills in a seamless steel pipe production line using a plug mill method, and the pass line of the raw pipe must be aligned at the minimum interval defined by the center axes of the two rolls. 2.
The tube is polished by a plug and two rolls while supported at three points by two rolls and shoes. This prevents buckling of the raw pipe.

That is, the reels 5A and 5B polish the raw pipe that has been elongated and rolled by the plug mill 4, and
This eliminates the inner surface streaks that occur in the tube, smoothes the inner and outer surfaces of the tube, and makes it possible to slightly reduce the wall thickness and expand the tube.

However, the tube shape after rolling by the reelers 5A and 5B changes due to roll wear and shoe wear of the reels 5A and 5B, and a predetermined tube shape can be obtained with high precision only by initial setting of the reeler rolling conditions. It is not possible. In particular, 2
If the reelers 5A and 5B of the stand are arranged in parallel, it is not appropriate because the rolling precision between the two reels 5A and 5B varies.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling the shape of a tube using a reeler, which can control the shape of a tube after reeler rolling with high precision, thereby improving product dimensional accuracy and yield.

In order to achieve the above object, the present invention biases the pass line of the raw pipe with respect to the minimum roll interval defined by the center axis of two rolls, and the raw pipe is rolled by two rolls and a shoe. In a pipe shape control method using a reeler in which the raw pipe is polished and rolled by a plug and two rolls under a point-supported state, the fields of the roll drive motors that respectively drive each roll are adjusted relative to each other. By doing so, the torque difference between both roll drive motors is adjusted, and the expansion rate of the raw pipe is controlled.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a plan view showing a rolling state of a reel to which the present invention is applied, and FIG. 3 is a front view of FIG. 2. In the reeler, the right roll 11 and the left roll 12 are cylindrical, the roll axes are arranged obliquely with respect to the horizontal, and the plug 13 is long cylindrical. The raw tube 14 that has been elongated and rolled by the plug mill in the previous step is transferred to the right roll 11.
The pipe is polished into a spiral shape between the left roll 12 and the plug 13, and the inner and outer surfaces of the pipe are finished smooth, and the right roll 11 and the left roll 12
The wall thickness is reduced to a thickness determined by the gap between the lower shoe 15 and the plug 13, and the tube is expanded under pressure contact with the lower shoe 15. In addition, right roll 11 and left roll 1
2 can be driven by roll drive motors 11A and 12A each consisting of a DC motor.

Here, the pass line PL of the raw pipe 14 is biased downward by about 6 mm, for example, with respect to the minimum roll interval region E defined by the center axes of the right roll 11 and the left roll 12. Therefore, the raw tube 14 is
It is possible to polish the tube under the three-point support condition of 5. Note that 16 is an upper shoe.

Therefore, in the above embodiment, by relatively adjusting the fields of the roll drive motors 11A and 12A, the torque difference between the two is adjusted, and the raw tube 14
The expansion rate of the tube can be controlled. Here, the tube expansion rate is the base tube after reeler rolling under an arbitrary torque ratio condition with respect to the standard outer diameter D ₀ of the tube after reeler rolling under the condition where the roll drive motors 11A and 12A are at the standard torque ratio. It is defined as the ratio of the outer diameter D. Moreover, the control of the tube expansion rate described above also enables control of the elongation rate of the tube 14 by the reeler based on the law of constant volume of the tube 14. Here, the stretching ratio is the standard length of the raw pipe after reeler rolling under the condition that the roll drive motors 11A and 12A are at the standard torque ratio.
It is defined as the ratio of the length L of the raw pipe after reeler rolling to L ₀ under an arbitrary torque ratio condition.

That is, even if there is a gap between the right roll 11 and the left roll 12 and the plug 13 and the thinning given to the raw pipe 14 is constant, the right roll drive on the side that feeds the raw pipe 14 toward the lower shoe 15 Motor 1
A torque of 1A is applied to the other left roll drive motor 1.
When the field of each roll drive motor 11A, 12A is relatively adjusted so that the torque is larger than the torque of 2A, the raw tube 14 is strongly pressed against the lower shoe 15, and the tube expansion rate becomes small. , the stretching ratio becomes large.
Therefore, the raw tube 14 after reeler rolling in this case is given a shape with a relatively small outer diameter and a relatively large length compared to the time of standard rolling. On the other hand, each roll drive motor 11 is configured such that the torque of the right roll drive motor 11A is smaller than the torque of the left roll drive motor 12A.
When the fields of A and 12A are adjusted relatively, the base tube 1
4 is weakly pressed against the lower shoe 15, the expansion ratio becomes large and the elongation ratio becomes small. Therefore, in this case, the raw tube 14 after reeler rolling is given a shape with a relatively larger outer diameter and a relatively smaller length compared to the standard rolled material.

Here, for example, the right roll drive motor 11
In order to increase the torque of A, it is necessary to perform field adjustment such as making the magnetic flux of the right roll drive motor 11A smaller, and to reduce the field current of the right roll drive motor 11A, Or it is necessary to increase the field resistance.

Next, the operation of the above embodiment will be explained. By adjusting the field of each roll drive motor 11A, 12A, the torque difference between the right roll drive motor 11A and the left roll drive motor 12A is adjusted, and for example, as shown on the horizontal axis in FIG. 1
1A torque T ₁ and left roll drive motor 12A
When the ratio T _{1 /} T ₂ to _{the torque T 2 of}
It changes as shown on the vertical axis of the figure. That is, by adjusting the torque ratio T ₁ /T ₂ , it is possible to control the outer diameter and length of the raw pipe 14 after being reeled. In addition, in this Fig. 4, the torque ratio
Raw pipe 1 after being rolled under the condition of T ₁ /T ₂ = 0.6
The outer diameter and length of No. 4 are defined as a reference outer diameter D ₀ and a reference length L ₀ , respectively.

According to the above embodiment, it is possible to control the tube shape after reeler rolling with high precision, and it is possible to improve product dimensional accuracy and yield. In particular, even when two reels are installed on a rolling line, by applying the present invention to both reels, the shapes of the products rolled by both reels can be made uniform.

As described above, the present invention biases the pass line of the raw pipe with respect to the minimum roll interval defined by the center axis of two rolls, and supports the raw pipe at three points by two rolls and a shoe. In a pipe shape control method using a reeler in which the raw pipe is polished and rolled by a plug and two rolls under the following conditions, by relatively adjusting the field of the roll drive motors that drive each roll, By adjusting the torque difference between the motors for driving both rolls and controlling the expansion rate of the raw tube, it is possible to control the tube shape after reeler rolling with high precision, improving product size control and yield. Become.

[Brief explanation of drawings]

Fig. 1 is a process diagram showing a general seamless steel pipe manufacturing process, Fig. 2 is a plan view showing the rolling state of a reeler to which the present invention is applied, Fig. 3 is a front view of Fig. 2, and Fig. 4 is a FIG. 3 is a diagram showing a control state of the tube shape according to the present invention. 11...Right roll, 11A...Right roll drive motor, 12...Left roll, 12A...Left roll drive motor, 13...Plug, 14...Made pipe,
15...Down show.

Claims (1)

[Claims] 1 The pass line of the raw pipe is biased to the minimum roll interval defined by the center axis of the two rolls, and the raw pipe is supported at three points by two rolls and a shoe, and the raw pipe is In a tube shape control method using a reeler that uses a plug and two rolls to roll a polished tube, the torque difference between the two roll drive motors can be reduced by relatively adjusting the fields of the roll drive motors that drive each roll. A pipe shape control method using a reeler that adjusts the expansion rate of the raw pipe.