Patent ID: 6817098
Filing Date: 2004-11-16
Classification: B21C,B21K,B23P,Y10T

Abstract:
A method of forming inner flanges in a bushing comprising:(a) providing an extruding die having a first passage with a diameter, a taper passage coaxially aligned with the first passage and a second passage with a diameter, which is aligned with the first passage; (b) providing a stepped base mounted under the extruding die, and the stepped base having a first end, a second end, a discharge hole and multiple stepped flat surfaces arranged in a stepwise manner with an uppermost flat surface at the first end of the stepped base under the extruding die and a lowermost flat surface at the second end of the stepped base, wherein the discharge hole is defined in the lowermost flat surface; (c) extruding a bushing with a following end, a leading end and an inner periphery into the first passage, wherein the leading end is extruded into the first passage; (d) pressing the bushing until the leading end of the bushing abuts the uppermost flat surface with a pressing block; (e) cutting the inner periphery of the bushing to shape an initial upward flange in a position corresponding to the taper passage in the extruding die with a flange punch; (f) aligning the extruding die with a lower adjacent stepped flat surface of the stepped base; (g) flattening the initial upward flange to form a final inner flange with a flat-head punch wherein the flat-head punch presses the bushing with the leading end abutting the lower adjacent stepped flat surface; (h) repeating steps (e) to (g) until the extruding die with the bushing is aligned with the lowermost flat surface, thereby forming a plurality of final inner flanges; and (i) removing the bushing with the final inner flanges through the discharge hole.