METHOD OF MANUFACTURING SEAMLESS STEEL PIPE

摘要

A method of producing a seamless steel tube to enable it to suppress not only the deviations in wall thickness occurring in the direction of reduction in a mandrel mill but also the derivations in thickness occurring at places deviating from the direction of reduction: measuring the wall thicknesses within the circumferential directions of a seamless steel tube 14 rolled in a production line comprising a mandrel mill 11 consisting of a plurality of reduction stands 111 to 115 having reduction rolls disposed in succession with the directions of reduction varied each other, and controlling, separately and individually based on the results of the measurement, the positions of both ends of each axis of the reduction rolls 114 , 115 in the final reduction stands of the mandrel mill 11 so that the deviations in wall thickness can be minimized.