DEVICE FOR ENDLESS ROLLING IN STRETCH REDUCER

PURPOSE:To reduce the inadequate parts in the sectional sizes in the end parts of pipes and to improve yield, by reducing the diameter in the end parts of base pipes, reheating the same and fitting and press sticking the top and tail parts of the preceding and succeeding base pipes then subjecting the pipe to endless rolling. CONSTITUTION:End working machines 14 are provided in front and rear of a reheating furnace 15 for base pipes, and the tail end part 1 of a preceding base pipe 11 is worked to a small diameter part having screw-like rugged parts. The top end part 2 of a succeeding base pipe 12 is worked to a small diameter part of which the inside diameter fits into the part 1. A pressing device 16 fits the parts 1, 2 of the pipes 11, 12 worked with the machines 14 in a coupling machine 19. Pinch rolls 17 press and stick the parts 1, 2 in the machine 19 by operating cooperatively with the device 16. Prior to the press sticking, the part 1 of the pipe 11 worked to the small diameter part having the screw-like rugged parts is cooled with a cooler 18 and the coupled parts of the parts 1, 2 of the base pipes coupled by the press sticking are cooled with a cooler 20. The coupled pipe is subjected to endless rolling with a stretch reducer 21, and the coupling parts are cut away with a cutter 22.