METHOD FOR CONTROLLING WALL THICKNESS OF STEEL PIPE WITH REDUCING MILL

摘要

PURPOSE:To enable production of a rolled pipe having a specified wall thickness by controlling a reducing mill in accordance with the required elongation rate calculated from the actually measured values of the weight of a blank material and the length of a base pipe and the elongation determined from a rolling schedule. CONSTITUTION:The relation between the required elongation rate in a reducing mill 6 consisting of plural roll stands and the controlled variable for the revolution pattern of the rolls of the entire roll stand is predetermined for every elongation which is the ratio in the sectional area of a rolled pipe 7 between the inlet side and outlet side of the mill 6. On the other hand, the weight of a blank material 1 and the length of a base pipe 4 after working with a mandrel mill 3 are respectively actually measured by a device 2 for measuring weight and a device 5 for measuring length and the required elongation rate for reduction is calculated from such actually measured values and the weight of the command blank material and the weight of the command base material in the same lot. The controlled variable for the revolution pattern of the rolls in the reduction is determined by a calculator 9 for control in accordance with said elongation and the required elongation rate and the rotating speed of the rolls of each roll stand provided to the mill 6 is automatically controlled.