Patent ID: 7069764
Filing Date: 2006-07-04
Classification: B21C,B21K,B62D,Y10S,Y10T

Abstract:
1. A series of die sets used in a method for manufacturing a hollow rack shaft, said series comprising: a first die set for forming a substantially flat and rectangular plate workpiece into a gutter-like shaped workpiece, said gutter-like shaped workpiece having a flat bottom portion, a pair of semi-circular bottom portions extending from each longitudinal side of said flat bottom portion, and a pair of leg-like side walls extending upwardly in parallel from each lateral side of said flat bottom portion and said semi-circular; circular; bottom portions, said first die set having a pair of dies with a pressing surface inclined in a longitudinal direction of said gutter-like shaped workpiece relative to a pressing surface of a second pair of dies so as to cancel elastic recovering of said gutter-like shaped workpiece when said gutter-like shaped workpiece is removed from a second die set; and said second die set for forming a row of rack teeth on said flat bottom portion of said gutter-like shaped workpiece, said second die set providing a complementary surface to said semi-circular bottom portions.