Patent ID: 6494073
Filing Date: 2002-12-17
Classification: B21D,B21K

Abstract:
A method of manufacturing a hollow rack bar by processing a part of a steel tube and forming a rack thereon, the method comprising:holding the steel tube in a set of split dies, wherein the split dies have an interior shape that encircles an entire circumference of the steel tube at the part to be processed and adjacent portions of the steel tube at both sides of the part to be processed; inserting a punch into an opening in the dies in a closed state of the dies and flattening the part of the steel tube; inserting a rack forming die into the opening of the dies, wherein the rack forming die has an inner shape that conforms to the opening in the set of split dies; holding the rack forming die in contact with the flattened part of the steel tube in the closed state of the dies; and inserting mandrels into the steel tube and forming a rack pattern corresponding to the rack forming die by ironing the flattened part of the steel tube from the interior of the steel tube.