Patent ID: 8051694

Claim:
A method of manufacturing a shaft with a first drawing die having a cylindrical first cavity defined therein which is open at both ends thereof and a second drawing die having a cylindrical second cavity defined therein which is open at one end thereof, wherein said first cavity has first and second openings and a first forming land disposed in said first cavity, diameters of said first and second openings being greater than a diameter of said first forming land, and said second cavity has a third opening, an inner space, and a second forming land disposed in said second cavity, diameters of said third opening and said inner space being greater than a diameter of said second forming land, said first cavity further including a first tapered part extending from said first opening to said first forming land, said second cavity further including a second tapered part extending from said third opening to said second forming land, and wherein an angle formed between said first tapered part and an axis of said first cavity is greater than an angle formed between said second tapered part and an axis of said second cavity, said method comprising the steps of: (a) inserting opposite end portions of a cylindrical solid rod respectively into said first opening and said third opening; (b) displacing at least one of said first drawing die and said second drawing die in a direction to cause said first opening and third opening to move toward each other, until the end portion of said cylindrical solid rod which is inserted in said third opening reaches a closed end of said inner space of said second cavity, thereby causing said second tapered part and said second forming land to draw said end portion of said cylindrical solid rod; and (c) displacing at least one of said first drawing die and said second drawing die in the direction to cause said first opening and third opening to move toward each other, thereby causing said first tapered part and said first forming land to draw the other end portion of said cylindrical solid rod.