Method for controlling tension between last two racks of multiple-rack rolling mill

Abstract

The invention discloses a method for controlling tension between last two racks of a multiple-rack rolling mill. The method comprises steps of A, measuring and performing calculation to obtain a tension sum actual value; B, determining enable signals of controllers at stages according to steel positioning signals, a speed value, a rolling force value and a tension value; C, calculating tension control transmission speed regulating variable under a threading or drifting mode; D, calculating and selecting the total tension control speed regulating variable and roll gap compensation amount. By means of the method, the rolling process is subdivided into multiple stages, and different controllers are chosen for different stages, the tension fluctuation between the last two racks can be reduced, and the tension is stabilized within the range of the preset value. A band elimination filter is arranged in a tension feedback channel, therefore, the interference is reduced, and the oscillation trend in the tension control is reduced. According to the method, roll gaps of the last rack are not adjusted, transmission speed of the last rack is not adjusted under the normal rolling mode, and plate shape quality of band steel is not affected.

Description

technical field [0001] The invention relates to a tension control method between the last two stands of a cold continuous rolling mill or a multi-stand skin pass mill, in particular to a tension control method between the last two stands. Background technique [0002] In the cold tandem mill or the multi-stand temper mill with rolling function, the entire production line is connected into a whole through the rolled strip steel to form a tension rolling process. Therefore, the rolling tension is a very important parameter in the production process of the rolling mill and must be strictly controlled. It not only affects the rolling process conditions, but also affects the product thickness accuracy and shape quality, and even makes the whole rolling process unstable. [0003] Modern tandem cold rolling mill units generally install tension rollers between the last two racks and in the entrance and exit areas to detect the actual tension of the strip. According to the actual va...

AI Technical Summary

Problems solved by technology

There is a control dead zone in this method. When the rolling force exceeds the limit range of the maximum or minimum rolling force, the normal tension control method will not adjust. During this period, the tension will not be kept constant, but will fluctuate within a dead zone. Until the rolling force is back within the limit range, the normal tension control starts working again

[0004] The tension control method between the last two stands above can achieve a good control effect in steady rolling, but the tension fluctuation is slightly larger in the process of speed up and down, threading and tail flicking, and as mentioned above, there is a control dead zone

In addition, in view of the increasingly high requirements for strip shape quality, in order to ensure the shape quality, a small constant rolling force control method is adopted on the last stand of many continuous rolling mills, and it is not allowed to adjust the last stand. The position of the roll gap, the tension control between the last two racks at this time cannot use the above method

Images