JPS6023888B2 - How to control the reduction of Leela Mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for controlling the reduction of a reel mill having rolls and guide shoes disposed on the exit side of a plug mill in a seamless steel pipe manufacturing process using a plug mill method.

In a seamless steel pipe manufacturing process line using the Mannesmann plug mill method, the raw pipe rolled and elongated by the plug mill is placed on the exit side of the plug mill.
The inner and outer surfaces of the raw tube are changed using a reeling mill (also called a tube mill), and some thinning and expansion are performed.
After that, it is sent to a sizing mill where it undergoes the final process of reducing the outer diameter. In this way, the rolling process using the IJ-ramill is a process immediately before the final process, so the dimensional accuracy of the raw tube in this process is the same as the dimensional accuracy at the exit side of the sizing mill, that is, the dimensional accuracy of the final product. This in turn has a significant impact on product yield.

In this Leela Mill, 80 to 95% of the Leela thickness loss
acts as the outer diameter of the outer diameter of the reel mill tube, so if the roll interval is controlled so that the thickness decreases to a constant value in the longitudinal direction, an outer diameter on the outlet side of the reel mill with a pattern almost similar to that of the outer diameter of the outer diameter of the outlet side of the plug mill can be obtained.

Therefore, in the past, focusing on the fact that if the load on the rolling motor is constant, the amount of thinning is almost constant, the current of the rolling motor is controlled to be constant, or the current in the longitudinal direction is controlled so that it follows a constant pattern. However, these methods involve uncertain factors because the ratio of the amount of wall thinning that affects the amount of external tube expansion is not clearly understood, and highly accurate control is difficult. In other words, if there is a change in the average temperature of the shell before rolling, a temperature drop in the longitudinal direction, a temperature drop due to skid marks, a change in the longitudinal wall thickness of the plug mill exit shell, etc., the outer diameter of the shell on the reel mill exit side may not be uniform in the longitudinal direction. However, the current during rolling changes, and if this is used as a control signal, the outer diameter may become non-uniform. On the other hand, as something similar to the present invention,
As shown in No. 6663, the average cross-sectional area in the longitudinal direction of the raw pipe is calculated from the weight of the billet weighed at the entrance of the heating furnace and the elongated length in the second pass of the plug mill, and the reduction during the two-pass rolling in the plug mill is calculated. The cross-sectional area distribution in the length direction of the raw tube is determined from the change in the amount and the change in the rolling load value, and these are used as the cross-sectional area information of the raw tube at the inlet side of the reel mill, and the feedforward of temperature information is used as the output of the reel mill. The rolling power of the reel mill is adjusted so that the cross-sectional area of the raw tube at the exit side of the J-ramil is constant throughout the entire raw tube and throughout the entire length of each raw tube by feedback of the cross-sectional clearing information regarding the raw tube on the side. There has also been proposed a method for controlling the rolling reduction of a ramille, in which the rolling power is set for each raw tube and the rolling power is changed as the rolling progresses.

However, even in this conventional example, since the force for expanding the outer diameter of the reel mill is not directly detected, there are limitations in improving accuracy as described above. The present invention has been made to eliminate the drawbacks of the secondary kiln, and even when there are fluctuation factors such as changes in the temperature of the Qin tube, the outer diameter of the shell on the outlet side of the reel mill can be adjusted.
It is an object of the present invention to provide a method for controlling the reduction of a reel mill that can be made constant in the longitudinal direction of the shell.

The present invention is a method for controlling the reduction of a reeler mill having a roll and a guide shoe, which is disposed on the exit side of a plug mill in a seamless steel pipe manufacturing process using a plug mill method, in which an outer diameter expansion force applied to the guide shoe is detected. , the roll interval is controlled so that the outer tube expansion force becomes a predetermined value,
The above objective has been achieved. Referring to the drawing below,
Examples of the present invention will be described in detail.

As shown in FIGS. 1 and 2, this embodiment uses a pair of rolls 10 and 12 facing each other, which are disposed on the outlet side of a plug mill in a seamless steel pipe manufacturing process using a plug mill method, and a pair of rolls 10 and 12 facing each other. A pair of guide shoes 14, 16
In a reel mill having a reel mill, a load cell 20 is interposed between one of the guide shoes, for example, the lower guide shoe 16 and the base 18, and the load cell 20 is detected by the two load cells. The interval between the rolls 10 and 12 is adjusted so that the force of the outer bulwark tube applied to the lower guide shoe 16 becomes a predetermined value. The external tube expansion force is determined by the dimensions of the material to be rolled (outer diameter,
(inner thickness), etc., and if the dimensions of the material to be rolled are constant, the outward expansion force will also be constant. Therefore, it is possible to keep the outer diameter of the shell constant in the longitudinal direction of the shell by detecting the outer diameter expansion force and controlling the rolling load of the rolls so that the outer diameter expansion force becomes a value determined by the dimensions of the material to be rolled. can. Guide shoe acting force P
(k9) is P=Q. ts. d. △d10B...
...m However, t: IJ - Reeler outlet wall thickness d: Reeler outlet outer diameter △d: Reeler tube expansion amount [(Reeler outlet outer diameter) - (Reeler inlet outer diameter)] Q'8: According to the constant formula approximated.

The constant Q of the m formula was determined by experiment and is approximately the same as the Sukegawa 5k9 side - bone. In addition, although 0 is adopted as the initial value for the P value, it is learned based on the outer diameter value after rolling (a value determined by an outer diameter meter). In the figure, 22 is a shell, 24 is a plug, and 26 is a hydraulic clamp.

The action will be explained below.

The shell 22 that has been rolled and elongated in a plug mill (not shown) is bitten into the reel mill from the left side in FIG. 2, and is placed in the state shown in FIG. After undergoing rolling, the inner and outer surfaces were improved.
Moved to the right in Figure 2. At this time, upper guide shoe 1
4 is arranged so as to lightly contact the shell 22, it is difficult to accurately detect the outer diameter expansion force from the upper guide shoe 14. On the other hand, the lower guide shoe 16 is attached in a predetermined state so that the outer diameter expansion force generated on the shell 22 can be detected. Therefore, when the outward tube expansion force detected by the load cell 20 disposed below the lower guide shoe 16 becomes larger than a predetermined value, the gap between the rolls 10 and 12 is opened and the If the outer diameter expanding force detected by the load cell 20 becomes smaller than a predetermined value, close the gap between the rolls 10 and 12 to reduce the outer diameter expanding force. enhance Since this external tube expansion force is hardly affected by the temperature change of the raw tube, it is possible to control the rolling down of the ramille with better responsiveness and reliability than the conventional current control. The relationship between the reeler gangway amount Δd and the guide shoe acting force P is shown in FIG.

Figure 3 shows the dimensions of the pipe after the reeler is 3600 x 12.4t.
The case of is shown. As shown in Fig. 3, in the case where the IJ and lar tube expansion amount of the raw pipe after reeling is 3600 x 12.4 t (reeler entrance outside diameter is 3400
) The roll interval may be adjusted so that the guide shoe acting force is approximately 12 x 1 pik9. In the above-mentioned embodiment, the set value of the outside-perspective force was set in advance, but a measuring device for measuring the outside diameter of the shell is further arranged on the exit side of the reel mill, and the outside diameter is It is also possible to modify the set value of the external tube expansion force according to the output of the measuring device. In this case, even more precise control becomes possible. In the above embodiment, the outer diameter expansion force was detected by the lower guide shoe, but the means for detecting the outer diameter expansion force is not limited to this, and the upper guide shoe may be used. It is also possible to use both upper and lower guide shoes.

Further, in the embodiment, the load cell 20 uses the hydraulic clamp 26 to connect the lower guide shoe 16 and the base 18.
Although the load cell is interposed between the two, the method of attaching the load cell is not limited to this.

As explained above, the present invention provides a method for controlling the lowering of a laminar mill, which includes a roll and a guide shoe, which are disposed on the exit side of a plug mill in a seamless pipe manufacturing process using a plug mill method, and which is applied to the guide shoe. Since the external expansion force is detected and the roll interval is controlled so that the external expansion force becomes a predetermined value, even when there are fluctuation factors such as temperature changes in the raw pipe, the external expansion force on the IJ-Ramil outlet side is The diameter can be reliably kept constant over its longitudinal direction.

In addition, since the above-mentioned outboard expansion force is detected without using a roll, it is extremely easy to detect the outboard outboard expansion force. Furthermore, since the above-mentioned outer bulwark tube force is detected from the outer bulge expansion force applied to the guide shoe, there is an excellent effect such that a separate outer bulge expansion force detection means is not required. -

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a reel mill in which an embodiment of the method for controlling the reduction of a reel mill according to the present invention is adopted, FIG. 2 is a longitudinal cross-sectional view taken along the Ro-Ro line in FIG. 1, and FIG. It is a figure which shows the relationship between the reeler tube expansion amount and the guide shoe action force. 10, 12... Roll, 14, 16 """ guide shoe, 20... Load cell, 22... Shell, 24... Plug. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a method for controlling the reduction of a reeler mill having rolls and a guide shoe, which are piped to the exit side of the plug mill in a seamless pipe manufacturing process using a plug mill method, an outer diameter expansion force applied to the guide shoe is detected, and the outer diameter tube force is detected. 1. A method for controlling the rolling reduction of a reeler mill, characterized in that the distance between the rolls is controlled so that the outer diameter expansion force value is optimal for obtaining the desired dimensions of the rolled material.