Using the barrel die Pia sir roll null barrel die Pia sir

摘要

PROBLEM TO BE SOLVED: To provide a barrel type piercer roll for preventing occurrence of any inner surface flaw.;SOLUTION: In piercing a hole in a billet by using a barrel type piercer roll, in the barrel type piercer roll for preventing the occurrence of any inner surface flaw, each curve of a profile of the barrel type piercer roll on the roll inlet side and the roll outlet side satisfies conditional expressions of 0.5DR ≤ Ri ≤ 3.0R, 1.0DR ≤ Ro ≤ 4.0Dr, and Ri ≤ Ro, (wherein DR denotes the outside diameter of the roll, Ri denotes the radius of the curved line of the roll inlet side, and Ro denotes the radius of the curved line on the roll outlet side).;COPYRIGHT: (C)2007,JPO&INPIT