JPS5728604A - Caliber roll - Google Patents

Abstract

PURPOSE:To roll a pipe so as to provide it with uniform wall thickness over all circumference, and to prevent the generation of a squarish inner face of the pipe, by making the drawing rate for the pipe's outer diameter at the middle point between the groove bottom and the flange part of a caliber smaller than the average value of the drawing rate at the groove bottom and that at the flange part. CONSTITUTION:In respect of calibers 1c-4c of caliber rolls 1-4 of a stand (i-1) and a stand (i), the groove bottoms are designated by G1-G4; and the middle points between inside edges of flange parts 1f-4f are designated by F1-F4. The points of contact on the caliber surface, made by tangents inclining at an angle of 45 deg. against a line connecting G1 to G2 or G3 to G4, are designated by M1-M4. The relation of outer diametral drawing rates xsig, xsif, xsim respectively between the points G3, G<4> and F3, F4 and M3, M4 of the roll of >=1 stands, the stand (i) for exmple, with the exception of the stand (i-1), is set by the equations I, II so as to make the wall thickness variation at the points M1, M2 between before and after the rolling process euqal to the circumferential variation of the average wall thickness similarly between before and after the rolling process.