Improving the Control Accuracy of the Strip Plate During Shaped Rolling Using Electric and Hydraulic Drives

Abstract

It is important to reduce the amount of metal waste caused by scrap edge and scrap ends in the process of rolling at plate rolling mills. The influence of the correlation of the elongation ratio during drawing and spreading on the geometric shape of the strip plate was estimated. The paper shows the advantages of rolling process forming a double-cone profile at the head and tail sections. The ASC technology was introduced, which makes use of the multipoint strategy of thickness setting along the strip plate length. The importance of improving the accuracy of automatic control of position of screw-down structures and thickness was established when this strategy is used. The paper shows the structure and characteristics of the thickness automatic control system of the plate mill 5000. The analysis of oscillograph records of the strip plate thickness was carried out during the shaping pass for the current settings of the thickness automatic control system. Some deviations were recorded, which were caused by the lag of the regulating signal with respect to the actual deviation of thickness during displacement of the screw-down structures. To improve the response speed of the thickness automatic control system and to reduce the dynamic lag, a method of thickness control with pre-control was offered. The research group considered the double-circuit thickness automatic control system with the feed forward control of the target signal and established the transfer function of the pre-control channel. The paper demonstrated the structure of the simulation model of interrelated electric systems of a reverse rolling stand providing the opportunity of the joint research of shaped rolling and forming of a bend at the head end of the strip plate. The circuits of individual blocks of the model were considered. Comparative analysis of time curves of the strip plate thickness was carried out for the implementation of the design and the developed control algorithms and the increase in the response speed of the thickness automatic control system was proved. The paper demonstrates the oscillograph records obtained during the implementation of the developed algorithm in the automatic process control system of the reverse stand of the plate mill 5000. As a result of their comparison with the oscillograph records of the designed settings of the thickness automatic control system, it was proved that the accuracy of the thickness control improved. The paper notes that the main technological advantage of implementation of the developed algorithm is improving of the final product quality.