Hydraulic circuit, adjusting roll pressure in rolling mills - includes stepper motor driving servovalve controlling variable displacement pump

摘要

Hydraulic adjusting device for rolling mills has a control piston in a servo valve employed to feed hydraulic fluid to a work cylinder which adusts the roll press.; the control piston is actuated by a stepper motor, and a feedback circuit is used between the work cylinder and the servo valve. Angular motion of the stepper motor is converted into a linear motion, which adjusts the control piston, by a spindle located in a ball nut which cannot rotate so it undergoes linear motion. The servo valve adjusts a variable displacement pump feeding fluid to the work cylinder; and adjustment of the pump rotates a second spindle causing the linear motion of a second ball nut which is an integral part of a housing contg. the stepper motor. The robustness of a mechanical-hydraulic control system is combined with the accuracy of an electrical system.