METHOD OF PIPES MANUFACTURE Russian patent published in 1996 - IPC

FIELD: tube-rolling mills, increased accuracy of geocentric dimensions of pipes by inner diameter and increased stability of pipes deformation process by drawing with following expansion on mandrel rod. SUBSTANCE: method provides, that pipe blank is subjected to drawing without mandrel usage in draw plate with cylindrical belt and with angle of working cone. Following pipe blank flaring is exercised on stationary cylindrical mandrel with double side truncated cones. The new thing in the method is that truncated cones are made symmetrical and each of them has angle of vertex equal to 12 - 16 deg and length of cylindrical part of mandrel is equal to length of drawing plate belt and also the fact, that diameter of mandrel cylindrical part is less than diameter of drawing plate belt by value of 0.8 - 1.2 of pipe blank wall thickness. EFFECT: improved process. 1 dwg, 1 tbl