JP2005161373A - Method for controlling shape in cold tandem mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape controlling method in a cold tandem mill by which defects in shape which is more liable to be generated at rolling stands of the preceding stage before and after the time when the changed point of the manufacturing kind is passed through a rolling stand are prevented and also the generation of trouble in a rolling mill is suppressed. <P>SOLUTION: When performing continuous cold rolling by continuously feeding a plurality of materials to be rolled by welding them in order from the inlet side of a continuous rolling mill in which a plurality of rolling stands are arranged in tandem, the deflection of work rolls and/or intermediate rolls is straightened by predicting the increment of deflection of work rolls and/or intermediate rolls in the rolling stand of the preceding stage from the increment of the load in the rolling stand of the preceding stage when rolling speed is lowered, calculating the amount of correction of a bender necessary to straighten the deflection of the work rolls and/or the intermediate rolls in the rolling stand of the preceding stage from the predicted value and outputting and operating the amount of correction of the roll bender. Similarly when the rolling speed is increased, the deflection of the work rolls and/or the intermediate rolls is straightened by predicting the decrement of the deflection of the work rolls and or the intermediate rolls from the decrement of the rolling load and calculating the amount of the correction of the roll bender necessary to straighten the deflection of the work rolls and/or the intermediate rolls from the predicted value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a shape control method for cold rolling with a rolling mill in which a plurality of rolling stands are arranged in tandem.

As a shape control method when performing cold rolling with a rolling mill in which a plurality of rolling stands are arranged in tandem, a shape actuator of the final rolling stand is used based on a measurement value of a shape detector arranged on the exit side of the final rolling stand. The method of controlling is common.
Even when materials with different materials and dimensions, that is, with different types of production, are welded and joined together, and continuously cold-rolled, basically the shape actuator of the final rolling stand is controlled. Yes.
For example, in Patent Document 1, a plurality of types of setup control of the final rolling stand are performed within a period from the time when the tension is lowered to the time when the tension is increased before and after the time when the type of the material to be rolled passes through the final rolling stand. Has been proposed.

  Moreover, in patent document 2, when carrying out cold rolling continuously with the cold rolling mill in which the some rolling stand was arranged in tandem, the center of the board width of the several places from which a distance from a board edge differs by making a rolling load change amount into a variable. In advance, a mathematical model that represents the amount of change in elongation difference with respect to the rolling speed is reduced within the period from the rolling speed deceleration area to the rolling speed acceleration area before and after the time when the change in production type passes through the final rolling stand. There has been proposed a method for setting or correcting the control amount of the work roll bender and / or the intermediate roll bender so that the predicted value of the load change amount is substituted into the mathematical model and the elongation difference change amount matches the target value. Yes.

  Furthermore, in Patent Document 3, when continuously cold-rolling with a cold rolling mill in which a plurality of rolling stands are arranged in tandem, the center of the plate width at a plurality of locations at different distances from the plate end using the amount of change in rolling load as a variable. The first mathematical model representing the change in elongation difference with respect to the first formula and the second mathematical model representing the change in elongation difference using the amount of change in tension as a variable are created in advance, and the change in manufacturing type passes through the final rolling stand. The predicted value of the rolling load change amount is substituted into the first mathematical model within the period from the rolling speed reduction region to the rolling speed increase region before and after the timing to perform the work so that the elongation difference change amount matches the target value. Set or correct the control amount of the roll bender and / or intermediate roll bender and substitute the tension change amount into the second mathematical model when changing the tension of the final stand so that the change amount of the elongation difference matches the target value. Rubenda and / or how to set the control amount of the intermediate roll bender has been proposed.

Japanese Patent No. 2752589 JP 2001-269706 A JP 2002-282918 A

The above-mentioned conventional shape control technology was developed for the purpose of controlling the exit shape of the final rolling stand in a cold tandem rolling mill, as represented by Patent Documents 1, 2, and 3. The shape is controlled at all times by controlling the shape actuator of the final rolling stand, especially the roll bender. In addition, the shape actuator of the final rolling stand may be operated based on the result of visual monitoring by the operator without performing shape control by constant control.
As described above, in the cold tandem rolling mill, the shape of the final rolling stand is generally controlled by shape control or the like, but such shape control is not normally performed in the preceding rolling stand. .

As a means to ensure the shape at the front stand in the cold tandem rolling mill, the shape from the set-up table stratified by conditions such as steel type, sheet thickness, sheet width of the rolled material at the TOP part of the material to be rolled There is a preset method for setting the actuator value. Further, in a rolling mill or the like that does not have such an automatic setup function, the actuator is operated so that the operator has a set value at the TOP portion of the material to be rolled.
As described above, the operation of the shape actuator at the front stand is generally set only at the coil TOP portion.

However, in such a method for operating the shape actuator of the front stand, depending on the type of the cold rolling mill, when trying to roll a very thin material by high-pressure rolling, a shape defect may occur on the front stand side. . In particular, this shape defect occurs in response to a rolling load fluctuation due to an increase in the reduction amount or a reduction in the rolling speed, and becomes more prominent as the rolling load fluctuation amount increases.
That is, when rolling an ultra-thin material under high pressure, the amount of reduction is inevitably increased even in the former rolling stand, and the biting angle of the material to be rolled with respect to the work roll is increased. Along with this, there are situations where rolling oil is difficult to entrain. In particular, when the rolling speed is low, the amount of decrease in the oil amount increases, and as a result, the lubrication decreases and the rolling load increases. In addition, in the case of high-pressure rolling, the speed on the pre-rolling stand side becomes even slower, and the increase in rolling load becomes significant.

As described above, when manufacturing an ultrathin material by high-pressure rolling using a plurality of stands, a shape defect occurs due to a significant change in the rolling load on the preceding rolling stand side, or a narrowing accident occurs.
The present invention has been devised to solve such problems, even if the change in the production type is at the time of rolling speed reduction and at the time of rolling speed increase before and after the time of passing the rolling stand, rolling An object of the present invention is to provide a shape control method for a cold tandem rolling mill that eliminates a shape defect that easily occurs in a preceding rolling stand due to a change in load and also suppresses the occurrence of troubles in the rolling mill.

The shape control method of the cold tandem rolling mill of the present invention achieves the object, and when performing cold rolling with a rolling mill in which a plurality of rolling stands are arranged in tandem, pre-rolling when the rolling speed is reduced or increased A work roll and / or intermediate roll of the preceding rolling stand is predicted from the predicted value by predicting a bending increase or decrease amount of the work roll and / or intermediate roll of the pre-rolling stand from the rolling load increase or rolling load decrease of the stand. A roll bender correction amount necessary for correcting the bending of the roll is calculated, and the roll bender correction amount is output and actuated to correct the work roll and / or intermediate roll deflection of the pre-rolling stand.
In addition to the work roll and / or intermediate roll deflection correction of the pre-rolling stand, the final shape is determined by controlling the shape actuator of the final rolling stand based on the measurement value of the shape detector placed on the exit side of the final rolling stand. Control can also be performed.
In addition, the description of the following "work roll of a pre-rolling stand" means "the work roll and / or intermediate roll of a pre-rolling stand".

In the present invention, it is necessary to predict the amount of increase or decrease in the bending of the pre-rolling stand work roll from the amount of increase or decrease in the load of the pre-rolling stand, and to correct the bending of the pre-rolling stand work roll from this predicted value. By calculating the roll bender correction amount, and outputting and operating the roll bender correction amount, it is possible to prevent the occurrence of shape defects at the preceding stage rolling stand. In particular, the present invention is effective against load fluctuations caused by speed changes when rolling under high pressure, and can reduce shape changes due to load fluctuations even with extremely thin materials.
In addition to the work roll bender control of the former rolling stand, if the shape actuator of the final rolling stand is controlled based on the measured value of the shape detector placed on the exit side of the final rolling stand, the shape-controlled cold rolled material Shape accuracy will be greatly improved.

An example in which the shape control method for a cold tandem rolling mill of the present invention is applied to a tandem rolling mill having, for example, a four-stage rolling stand as shown in FIG. 1 will be described.
A continuous rolling mill 1 in which 6-high rolling mills 1st to 4st are arranged in a 4-stage tandem from the upstream side in the rolling direction of the material S to be rolled was used. The load meters 2-1 and 2-2 for measuring the rolling force are attached to the preceding six-high rolling mills 1st and 2st, and the fluctuation amounts of the rolling load detected by the load meters 2-1 and 2-2 are respectively shown in the process computer 3. -1 and 3-2 are input, the respective work roll deflection changes are predicted, and the roll bender correction amount necessary to correct the respective deflections of the preceding six-high rolling mill 1st and 2st work rolls from this predicted value And the signal is transmitted to the respective vendor operation means 4-1, 4-2.

In the continuous rolling mill 1 described in the present embodiment, the shape detector 5 is disposed on the exit side of the final rolling mill 4st, and a load meter 12 is attached to the final six rolling mill 4st. Based on the signal from the detector, etc., a necessary shape control amount may be calculated by the process computer 13, the control amount of the shape control means 14 may be corrected, and shape control may be performed by the final rolling stand 4st. .
The steel strip that has been continuously cold-rolled by the rolling stand 1 is sent to the running shear 6 as usual, separated for each production type, and taken up on the take-up reel 7.

Next, from the fluctuation amount of the rolling load detected by the load meters 2-1 and 2-2, a prediction method of each work roll deflection amount, each work roll deflection correction amount based on the predicted value, and the necessary amount thereof A method for calculating the roll bender correction amount will be described.
In general, the relationship between the rolling speed and rolling load during rolling is such that the higher the rolling speed, the lower the rolling load. As the rolling speed decreases, the rolling oil film becomes thinner and the friction coefficient increases, so the rolling load gradually increases. To go. As shown in FIG.

When setting with the preset method adopted in the shape control method of the conventional cold rolled material, if the preset value is determined based on the load in the state of FIG. When the preset value is determined based on the load at point B, the shape of the load reducing portion such as point A is in the middle elongation direction.
Furthermore, when rolling an ultra-thin material by high-pressure rolling, the load fluctuation amount between A and B becomes remarkably large, and rolling troubles due to shape defects occur.

In order to suppress these shape defects, it is necessary to correct the roll bender force as the rolling load increases or decreases.
As a method of correcting the roll bender force as the rolling load increases / decreases, the roll bending amount is obtained by elastic deformation analysis of the roll using a split model, and the roll bender correction amount is output to correct the bending amount. A model calculation method may be adopted. However, in the sense of simplification, it is preferable to adopt a table lookup method in which the relationship between the rolling load derived from empirical rules and the roll bender correction value is set in a table.

In the present invention, a table system as shown in Table 1 is adopted.
In addition, this Table 1 is a table | surface employ | adopted when finishing and cold-rolling the pickled steel plate with a plate width of 1000 mm and a thickness of 2.3 mm of low deoxidized low carbon steel to a final thickness of 0.34 mm.
In this method, a point such as point A in FIG. 2 is taken as a reference, and when the rolling load increases from the reference value, the roll bender force is corrected so as to increase by the value calculated from the values in Table 1, and vice versa. When the rolling load is reduced, the roll bender force is corrected to be reduced.

For example, when the rolling load increases, from Table 1, if the load increases in the range up to 6000 KN, the correction value is 0, that is, no correction is necessary. When increasing to 6000 KN or more, it is necessary to correct | amend a roll bender force based on the numerical value of Table 1.
When the load is increased from 5000 KN to 8500 KN, the correction value is 0 from 5000 KN to 6000 K, 10 / (7000-6000) at a rate of 10 / (7000-6000) from 6000 KN to 7000 KN, and the correction value of 10 KN / Ch from 7000 KN to 8000 KN. Up to 20 / (8000-7000) at a rate of 1000KN increasing part 20KN / Ch, and from 8000KN to 8500KN at a rate of 30 / (9000-8000) at a rate of 500KN increasing part 15KN / Ch. It is only necessary to output the integrated value 45KN / Ch as a correction value and adjust the roll bender force to increase by that amount.

For example, when cold rolling is performed under the roll bender force conditions as shown in Table 2, when the rolling load increases due to deceleration such as coil replacement, the above method is used with the numerical values shown in Table 2 as the standard roll bender force The correction value calculated by is added to the reference value.
Conversely, when the rolling load decreases, a correction value that decreases the roll bender force at the same rate as the increased correction value is output, and the bender value at the same rolling load is corrected to be constant. . That is, when the rolling load decreases from 9000 KN to 8000 KN, a correction value for decreasing the roll bender force at a ratio of 20 (KN / Ch) / (9000-8000) (KN) is output.

FIG. 3 shows the relationship between the load value when the load increases and the total output value of the roll bender correction amount. This is an example of the load increasing side and is a diagram showing how the total output value of the roll bender correction amount is integrated as the load on the horizontal axis increases. For example, when the load increases to 8500 KN, it means that it is necessary to add a correction value of 45 KN / Ch indicated by an arrow in the figure.
Note that Table 1 and FIG. 4 are prepared in advance according to the steel type, the plate thickness, the plate width, and the like, as described above.

In the above, the roll bender control method which follows the load about the pre-rolling stand in the cold tandem rolling mill of this invention has been demonstrated.
By adopting this method, it is possible to reduce shape defects due to load fluctuations in the preceding rolling stand accompanying fluctuations in speed when an ultrathin material is produced by high-pressure rolling. Also, by adopting the work roll bender control of the pre-rolling stand, mill troubles that have conventionally occurred at a frequency of 2 to 3 times per month can be prevented, and the final rolling stand shape control method can be combined to further increase the shape. Cold rolled steel sheets with excellent accuracy can be produced.

Conceptual diagram showing a control system in a cold rolling mill in which a plurality of rolling stands are arranged Diagram showing the relationship between speed and load during rolling Graph showing the relationship between the load value and the increased roll bender correction value

Explanation of symbols

1: Continuous rolling mill 2-1, 2-2: Load cell 3-1, 3-2: Process computer 4-1, 4-2: Bender operation means 5: Shape detector 6: Bridle roll 7: Running shear Machine 8: Take-up reel 12: Load cell
13: Process computer 14: Shape control means

Claims (2)

  When performing cold rolling with a rolling mill in which a plurality of rolling stands are arranged in tandem, the work roll of the preceding rolling stand and / or the rolling load increase amount or the rolling load decrease amount of the preceding rolling stand when the rolling speed decreases or increases A roll bender correction amount required to correct the deflection of the work roll and / or the intermediate roll of the preceding rolling stand is calculated from the predicted value by predicting the amount of increase or decrease in deflection of the intermediate roll, and the roll bender correction amount The shape control method of a cold tandem rolling mill characterized in that the work roll and / or intermediate roll deflection correction of the preceding rolling stand is performed by outputting and actuating.   In addition to the work roll and / or intermediate roll deflection correction of the pre-rolling stand, the final shape is determined by controlling the shape actuator of the final rolling stand based on the measurement value of the shape detector placed on the exit side of the final rolling stand. The shape control method for a cold tandem rolling mill according to claim 1, wherein the control is performed.

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