Patent ID: 6604663
Filing Date: 2003-08-12
Classification: B21B,B21C

Abstract:
A control method of hydraulic pinch rolls wherein a strip is held between upper and lower pinch rolls to guide the strip, the method comprising the steps of:providing an upper pinch roll having end portions and a lower pinch roll, with hydraulic cylinders that independently support the end portions in an axis direction of the upper pinch roll; adjusting an excurrent/incurrent amount of an operation oil in the hydraulic cylinders with servo valves; detecting piston positions of the hydraulic cylinders with position detectors; detecting a pressing force of the hydraulic cylinders with pressing force detectors; and controlling the servo valves with a right control unit and a left control unit, whereby positional control and pressing force control of the upper pinch roll is performed by controlling the servo valves, wherein set values of the pressing force control are provided for the right control unit and the left control unit, and are independently corrected by a correction value calculated based on a right difference and left difference, respectively, of the piston positions of hydraulic cylinders.