THICKNESS CONTROLLING DEVICE FOR SEAMLESS TUBE ROLLING MILL

PURPOSE:To make thickness of tubes constant by calculating the amount of drawing position control that makes the difference between calculated thickness in the outlet side of a rolling mill and target thickness in the outlet side zero, and giving it to a drawing position controlling device. CONSTITUTION:An inlet side speed detector 40 detects the speed (v) of a rolling material in the inlet side of a rolling mill and an outlet side speed detector 50 detects the speed V of the rolling stock in the outlet side. An outlet side thickness calculator 810 inputs the output (v) and V of detectors 40 and 50. At the same time, it inputs inlet side sectional area (a) and plug diameter D of storage devices 90 and 100 and calculates the thickness T of the rolling material in the outlet side of the rolling mill. A drawing position calculator 820 calculates and outputs a drawing position control signal DELTAS that makes the difference between T and T' zero using calculated outlet side thickness T and target thickness T'. The amount of rolling position control DELTAS is given to a drawing position controlling device 60, and drawing position of rolls 20 is corrected. By this way, the thickness in the outlet side of the rolling mill is controlled to the target value T' and a seamless tube of desired thickness is manufactured.