METHOD FOR PREVENTING GENERATION OF BURR AT THE TIME OF PIERCING PIPE MATERIAL WITH PIERCER

摘要

PURPOSE: To prevent formation of annular or fin-like burrs at the rear end of a base pipe in production of the base pipe for production of a steel pipe by piercing of a pipe material billet by a piercing plug and piercer roll. ;CONSTITUTION: The central part region at the rear end 7 of the pipe material billet 1 is heated to a high temp. to melt by a gaseous acetylene and oxygen flame or gaseous plasma flame 3, etc., from a gaseous flame nozzle 2 before piercing, by which the billet is provided with a hole 4 having a proper diameter and depth in a method for obtaining the base pipe for production of the steel pipe by piercing of the pipe material billet 1 by the piercing plug. The size of the hole 4 is set at a hole diameter of ≥20 to ≤60% of the diameter of the pipe material billet and a hole depth of ≤10 to ≤30% of the diameter of the pipe material billet.;COPYRIGHT: (C)1995,JPO