FORMING MACHINE OF ELECTRIC WELDED STEEL PIPE

PURPOSE:To prevent productivity of a steel pipe from dropping due to a rolling phenomenon by providing a centering device of a strip and a rolling quantity measuring device on the entry of a device and in the forming process, respectively, when manufacturing an electric welded steel pipe by forming and welding the strip in the shape of a pipe. CONSTITUTION:An electric welded steel pipe is manufactured by forming gradually a strip 1 in the shape of a pipe by forming roll groups 2-3 of the first stage, forming roll groups 5-11 of the second stage, and fin pass roll groups 12-14, and welding both edge parts. In this device, a centering device 16 of the strip 1 is provided on the entry, the strip 1 is advanced exactly to the center position of the device, and also a rolling quantity measuring device 15 is provided on the way of the forming roll groups 5-11 of the second stage. A rolling displacement quantity DELTAh of both edge parts of a tubular formed article is measured by this device, an entry offset quantity is given by the centering device 16 so as to negate said quantity, and a rolling quantity is stabilized to a position of about zero, by which an electric welded steel pipe is manufactured with a high productivity.