Due to irregularity in the rim section possesses the spiral pattern keeps being pushed out from the bearing of the production device and

摘要

PROBLEM TO BE SOLVED: To make it possible to produce a patterned outer peripheral circular material with simple equipment constitution by setting a spiral pattern forming tool in such a manner that its cutting tool bites the outer peripheral part of the outer peripheral circular material by inclining toward the longitudinal axial line direction of the outer peripheral circular material. ;SOLUTION: Since the inclined blade part 12 of the spiral pattern forming tool 10 consists of the inclined blade part 12 inclined with an extrusion axial line direction, the spiral pattern forming tool 10 receives the force in a rotating direction from the outer peripheral circular extrudate 1 by the bite during the extrusion. The spiral pattern forming tool 10 of an annular planar shape receives the extrusion migration force of the outer peripheral circular extrudate 1 during the extrusion and is pressed to a backer 8 side, i.e., spherical bodies 15... and the spiral pattern forming tool 10 is rotated by itself. While the inclined blade part 12 on the inner periphery thereof maintains the bite state around the extrusion central axial line, the inclined blade part successively circumrotates by itself around the outer peripheral part of the outer peripheral circular extrudate 1 during the course of the extrusion. The spiral patterns 1a are formed by the interaction of the circumrotation action and the extrusion migration of the outer peripheral circular extrudate 1.;COPYRIGHT: (C)1999,JPO