METHOD AND DEVICE FOR SPINNING PIPE BODY

PURPOSE:To reduce the cost of a core bar and to replace rapidly and easily the core bar, by bringing the core bar and a spinning roll into rolling contact with the inner and outer surfaces of a blank pipe respectively, and performing an elongation rolling by moving both synchronously from the front end to the base end of the pipe. CONSTITUTION:The head part of a core bar 5 and a spinning roll are placed face to face at the inside and outside of the surface of the front end of a blank pipe M by holding rotatably the base end of the pipe M by a chuck 23 of a headstock 2 and moving a tailstock 3 for rotating the bar 5 and a roll stand 4 for supporting the spinning roll to the position as shown by a solid line. Next, an elongation rolling is performed, by starting a heating of the pipe M by an induction heating coil, and rotating the pipe M and the bar 5 around the axis at a prescribed speed while pressing the surface of the pipe M by the spinning roll and further moving the tailstock 3 and the stand 4 on a bed 1 in the direction of an arrow by driving them synchronously. Thus, special steel is used only for the head part of the bar 5, and the extracting and replacing operations of the core bar 5 are performed easily.