JPS591014A - Controlling method of tension between stands in multi- stand continuous rolling - Google Patents

Abstract

PURPOSE:To properly control the tension of a material to be rolled between stands, and to stabilize a rolling operation, by setting the standard value of a torque arm as a function of a rolling load, in controlling the tension of the material in a multi-stand continuous mill. CONSTITUTION:In feeding a material to be bitten to the 2nd stand after it is rolled by the 1st stand, a torque arm which is the ratio between a rolling torque and a rolling load at each stand is continuously stored rized as a function of a rolling load by a torque-arm storage device, while the material is rolled in a tensionless state before it is bitten by the 2nd stand. While the material is rolled in a tensioned state after it is bitten by the 2nd stand, a torque-arm value corresponding to a rolling load is extracted as a standard value at each time in accordance with the function stored in the device to adjust the rotating speed of a rolling roll so as to make the deviation of the actual torque-arm value to zero or a previously determined value. Thus the rolling operation is made stable, and the deteriorations of the dimensions and shape of the material are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling tension between stands of a multi-stand continuous rolling mill.

In general, in a multi-stand continuous rolling mill, if there is poor roll speed setting or non-uniform material speed on each stand, tension or compressive force will act on the material between the stands, adversely affecting the dimensions and shape of the material.

In particular, during hot rolling, the material deforms plastically, leading to product defects, so it is necessary to suppress the inter-stand tension or compressive force to zero or a constant value by some method.

As a tension control method between stands, for example, a loop method,
A current memory method, a torque memory method, a torque arm memory method, etc. are known.

In the loop method, a looper is provided between stands to apply a predetermined tension to the material, or a free loop is used to achieve no tension, but it cannot be applied except when rolling a material with good flexibility. The current memory method can be widely applied regardless of the size of the material, but since it assumes that the rolling torque (#motor current) is constant, changes in the rolling torque due to the temperature distribution of the material will cause a change in tension. Separation is not possible and accurate tensionless rolling cannot be achieved. The torque memory method also has the same drawbacks as the current memory method. On the other hand, in the torque arm memory method, even if there is a temperature distribution in material C, this causes fluctuations in both rolling torque and rolling load. It changes mainly depending on the tension component. Therefore, since this torque arm memory method can achieve more accurate tensionless rolling than the current memory method or the torque memory method, it is currently most commonly used as a tensionless control method. However, the torque arm memory method cannot always guarantee accurate tensionless rolling and has the following drawbacks.

That is, in the torque arm method, the leading end of the material is bitten in the N11L1 stand, and after entering steady rolling, the torque arm value in the Nll stand is stored. Then, when the tip of the material is bitten by the M2 stand, tI
If the roll rotational speeds of the kL1 stand and the N12 stand are not well matched, tension or compression forces will act between the stands, and the torque arm of the IVk11 stand will show a value different from the above memorized value, so this should be returned to the original value. The roll rotation speed is adjusted so as to return to the original position. However, the torque arm of the positive 1 stand does not actually maintain a constant value even during tensionless rolling. That is, when the rolling load changes due to the temperature distribution of the material, etc., changes in the roll gap due to changes in the elasticity of the rolling stand and rolls cause fluctuations in the torque arm6. I'm standing still. Therefore, even if torque arm control is performed to match the torque arm to a certain memorized value after the leading edge of the material is bitten into the second stand, true tensionless rolling will not occur and tension errors will occur. become.

An object of the present invention is to set the reference value of the torque arm during inter-stand tension control not as a single memorized value, but to set it floatingly as a function of the rolling load. The purpose is to compensate for deficiencies. This purpose, according to the present invention, is to continuously learn and memorize the torque arm of each stand in multi-stand continuous rolling as a function of rolling load during tensionless rolling before the rolled material is bitten by the next stand. Then, during tension rolling after the rolling material is caught in the next stand, the torque arm value corresponding to the rolling load value is taken out as a reference value according to the learned and memorized function. This is achieved by adjusting the roll rotation speed so that the deviation of the actual torque arm value from the reference value is maintained at zero or at a certain predetermined value.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

In FIG. 1, 1 is a rolling material, 10 is a rolling roll, P is a rolling load, and G is a rolling torque. Temperature distribution (such as skid marks) in the material causes the roll gap to vary and the geometrical relationships to change, as shown by the solid and dashed lines. Since this change brings about a change in the torque arm, it is necessary to change the reference value of the torque arm in accordance with the variation in the roll gap in order to achieve true tensionless rolling. In this case, since the variation in the roll gap is proportional to the variation in the rolling load, the reference value of the torque arm may be changed in accordance with the variation in the rolling load.

The relationship between rolling load P and torque arm λ (=G/P) is generally expressed by a characteristic curve as shown in FIG. Since it is impractical to obtain this characteristic curve from the rolling theoretical formula, in the present invention, the method is performed in a tensionless state (that is, in the case of the 11m1 stand, the 11kL1 stand is rolling and just before the tip of the material is bitten by the M2 stand). curve a in Fig. 2 from the measured values of the torque arm and rolling load between
b is learned and memorized. If the range of the measurement curve ab obtained through such learning and memorization is insufficient during tension control, a straight line aa' or bb', which is an extension of the slope of point a or point d, can be created by calculation. According to the curve aa'bb' obtained in this way, the value of the torque arm λ corresponding to the value of the rolling load P at each time is taken out, this is given as the reference value of the torque arm, and the torque arm is adjusted to this reference value. By adjusting the roll rotation speed so that the deviation of the actual value of is equal to zero or a certain predetermined value, the tension between the stands can be controlled to the target value.

Next, with reference to FIGS. 3 and 4, the method of the present invention will be specifically explained, and the configuration of an apparatus for carrying out the method of the present invention will be illustrated.

Figure 3 shows the state from immediately after the tip of the material is bitten by the IVh1 stand to just before it is bitten by the Ugly 2 stand, and Figure 4 shows the state after the tip of the material is bitten by the IVh2 stand. It shows the status of.

In FIGS. 3 and 4, the positive 1 stand is shown with the rolling roll 10 and the rolling motor 11, and the positive 2 stand is shown with the rolling roll 10 and the rolling motor 11.
The stand is shown with rolling rolls 20 and rolling motor 21. 1 is a rolled material.

The rotational speed of each rolling motor 11, 21 is detected by a speed generator 12.22 and feedback-controlled by a speed control device 13.14. Speed control device 13゜14
A rotation speed setting value N:o, N2 is input from a rotation speed setting device (not shown). 14.24 motor current detector 19.29 and speed generator 12.22
This is a rolling torque calculator that calculates rolling torque from the detection output of 16.26 is the rolling load detected by the rolling load detector 15.25 and the rolling torque calculator 14.24
This is a torque arm calculator 16.26 that calculates a torque arm from the rolling torque calculated by. 1'l,
27 is a torque arm calculator 1 corresponding to various values 6 of the rolling load detected by the rolling load detector 15 and 25.
6. By storing the values of the torque arm input from 26 through the switches S
A function to obtain the function curve ab (or a'ab'b) shown in the figure, and output a reference value of the torque arm according to the value of the rolling load detected by the rolling load detector 15 according to the stored function curve. This is a reference torque arm storage device having the function of 18.28 is switch 51-
2 and 822, which corrects the rotational speed set value so that the actual torque arm value of the torque arm calculator 16 coincides with the reference value given by the reference torque arm storage device 17.27. be. The correction value applied from the tension regulator 18.28 via the switches 813 and 823 is superimposed on the set value N1°e''M) and input to the speed control device 13.23.

The rotation speed of the motor 11 of the Nnl stand is the set value N1:
As soon as the rolled material 1 is held in the N111 stand, the switch 811 is turned on as shown in the figure, whereby the reference torque arm storage device 17 starts the learning and memorizing operation. By storing the value of the torque arm calculated by the device 16 in correspondence with the value of the rolling load from the rolling load detector 15, the rolling load-torque arm function curve ab shown in FIG. 2 is learned and stored. In this case, there is generally a large variation in temperature distribution at the tip of the material 1, so the roll gap varies.

Therefore, the variation in the rolling load is large, and this has the advantage of making it possible to plot many torque arm operating points over a wide range of rolling loads. This learning and memorizing operation is performed until just before the tip of material 1 is bitten by the Nn2 stand.

As soon as the tip of material 1 is bitten into the Nn2 stand,
As shown in FIG. 4, the switch 821 is turned on on the N112 stand side, and the reference torque arm storage device 27 starts the same learning and storage operation as described above.◇At the same time,
As shown in Figure 4, on the tkl stand side, switch 11
is turned off, the reference torque arm storage device 1
7 is shifted from the previous read mode to the read mode. That is, the reference torque arm storage device 17 is
The torque arm value corresponding to the input data from the rolling load detector 15 is output according to the rolling load-torque arm function curve obtained by learning and memorizing. When the rolling load value outside the range of the measurement curve ab is inputted to the system [17], as already described in the explanation of FIG.
A desired torque arm value can be output.

The data read out from the device 17 in this way is passed to the input of the tension regulator 18 as a torque arm reference value. At the same time as switch 811 is turned off, switches 812 and 8
13 has already been turned on as shown in FIG. A roll speed correction signal can be generated so that

Thereby, the tension between the stands can be accurately controlled to zero or a predetermined value.

The above operation is performed using Nn3 whose material tip is not shown.
If this is repeated during the process in which the stands are sequentially engaged, it is possible to achieve zero-tension control or constant tension control over all the stands.

In the embodiment shown in FIGS. 3 and 4, the tension regulator 18
．． Although the output of 28 is used as a speed correction signal for the upstream stand, it is also possible to use it conversely as a speed correction signal for the upstream stand.

That is, the tension adjuster 18 may act on the speed control device 23 of the Nn2 stand, and the tension adjuster 28 may act on the speed control device of the 1Jn3 stand (not shown). Furthermore, the output of the tension adjuster can be applied successively to all the stands on the upstream side or the downstream side. Alternatively, the deviation signal between the torque arm reference value and the torque arm actual value is input to a non-interference control device for all stands, and the speeds of all stands are corrected so that all stands do not interfere with the tension. You can also do it.

It is desirable that the functions of the computing units 14, 16, 17, 24, 26, 27 and the switches 811, 812, 821, 822 be realized by a digital processing device such as a microcomputer. Furthermore, the regulator 18.28, switches S13 and S23, speed settings (N, o, N2), and part of the speed control device 13.23 can also be combined as a DDC device.

The present invention can be applied to the field of rolling long steel such as wire rods and E-shaped steel bars, and the field of plate rolling such as hot strip, and in particular, the looper conventionally used in IJ tubes can be omitted. , it can be applied not only to the hot rolling field as described above, but also to cold rolling.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of geometric changes in rolling conditions, Figure 2 is a characteristic curve diagram showing the relationship between rolling load and torque arm in the absence of tension, and Figures 3 and 4 are diagrams of rolled material. FIG. 3 is a diagram for explaining an embodiment of the present invention in relation to a progress state. 1... Rolling material, 10.20... Rolling roll, 11
．． 21... Rolling motor, 12.22... Speed generator, 13.23... Speed control device [, 14, 24... Rolling torque calculator, 15.25... Rolling load detector, 1
6.26...Torque arm calculator, 1'l, 27...
- Reference torque arm storage device, 18.28... Tension adjuster, 19, 29... Motor current detector. Sai 1 figure 't' 2 figure

Claims (1)

[Claims] The torque arm of each stand in multi-stand continuous rolling is continuously learned and memorized as a function of rolling load during tensionless rolling before the rolled material is bitten by the next stand, and the rolled material is bitten by the next stand. During tension rolling after rolling, the torque arm value corresponding to each rolling load is taken out as a reference value according to the learned and memorized function, and the deviation of the actual torque arm value from this reference value is zero. Alternatively, an inter-stand tension control method in multi-stand continuous rolling, characterized by adjusting the roll rotation speed so as to maintain it at a certain predetermined value.