Control of speed modes of heavy-plate mills rolling.

Abstract

Control of speed modes on heavy-plate mills is one of the factors that determine the efficiency of the rolling process. The choice of speed controls influences the mill productivity, geometric dimensions of the rolled product (longitudinal thickness variations) and compliance with the set temperature mode which determine the mechanical properties of the rolled product, etc. The article considers the limitations in the choice of speed controls which can be divided into two groups: limitations of the capabilities of rolling engines and technological limitations. The first group is determined by the allowable engine under the conditions of reliable current switching on the collector and the maximum allowable engine speed. Technological limitations of speed controls are considered in the paper as well. The speed of grasp is limited to the maximum under the condition of metal grasp without skew, blows and dynamic torque overloads in spindles and maintenance of constant grasp without slipping, as well as the possibility of prevention of emergencies. Steady (maximum) rolling speed can be limited to the maximum by the conditions of rolling stability and prevention of sticking of metal to the rolls. The rate of metal release from the rolls is usually chosen in the way so that the pause stipulated by the braking of the sheet on the roller conveyor and its subsequent return to the rolling mill would not exceed the operating time of the pressure mechanism. In some cases, the release rate can be determined by other technological operations. The maximum acceleration of the main drive of the horizontal mill is limited by the conditions of slipping of the working roll towards the support roll. The paper also considers rational speed graphs of rolling on heavy-plate mills. They are the most common type of high-speed rolling graphs on heavy-plate mills. The listed above solutions for the control of high-speed rolling modes can be used in the development of APCS of heavy-plate mills rolling.