US 6,018,977 A · Method of forming a cylindrical boss and a die therefor

Abstract

A crude work having a cylindrical boss formed integrally with a base plate is processed to a final product by a press work without using additional machining. An inner diameter of the boss is enlarged by a punch, and at the same time an outer diameter of the boss is shrunk by an outer die, while the work is supported on a cushion ring to which a force against the movement of the punch and the outer die is applied. Some of the material constituting the cylindrical boss is squeezed, and a bulge is formed at a foot of the cylindrical boss out of the material squeezed. Since the bulge is fromed in a confined space in the die structure, no crack or defect develops in or on the bulge. The bulge is further compressed by a press work to form a flat flange out of the bulge. The cylindrical boss having the flange formed integrally therewith is used as a center boss for holding a bearing of a rotary machine.

Claims4

Dependent claims

A method of forming a cylindrical boss, the method comprising steps of:

positioning a work having a crude cylindrical boss formed on and integrally with a base plate in a first die, the first die having a first plate, a cushion ring slidably supported in the first plate, a first punch slidably movable into the cushion ring and an ironing die disposed outside of the first punch, so that the work is supported on the cushion ring;
enlarging an inner diameter of the crude cylindrical boss by forcibly inserting the first punch into the crude cylindrical boss;
ironing an outer diameter of the crude cylindrical boss, simultaneously with the enlarging step, by forcibly sliding the ironing die along the outer diameter of the crude cylindrical boss;
applying a pressure, during the enlarging and ironing steps, to the work in a direction against a force applied to the work by enlarging and ironing the crude cylindrical boss;
and
thereby forming the cylindrical boss having a bulge at an inside foot thereof, the bulge being formed with material deformed from the crude cylindrical boss.

3 more elements

Dependencies are inferred from the claim text.

Method of forming a cylindrical boss and a die therefor

Life of this patent

Method of forming a cylindrical boss and a die therefor

Life of this patent

Abstract

Claims4