MANUFACTURE OF SEAMLESS STEEL PIPE

PURPOSE:To prevent faulty biting and to obtain a seamless steel pipe having a uniform thickness by rolling a thickness of pipe end part in a tapered shape on a rolling stage through a piercing mill or an elongator of Mannessmann type, then subjecting to elongation rolling and rolling the thickness of the pipe end part in a tapered shape. CONSTITUTION:In the stage of rolling the pipe end part in a tapered shape so that the thickness of the pipe end part becomes thinner toward the pipe end the rolling is performed without causing a faulty biting and a faulty shape of the pipe end. Furthermore, the blank pipe is elongation rolled by a succeeding plug mill and at the time of rolling the pipe end part in a tapered shape, a failing to roll caused by the faulty biting, etc., are not caused and the seamless steel pipe having uniform thickness is obtained in the last drawing roll mill.