| 摘要 |
PURPOSE:To make a rack shaft light weight without a lowering in strength by inserting an auxiliary rod which is shorter than a hollow rod into the hole of the hollow rod and by providing a rack tooth on the outer surface of the insertion part of the hollow rod. CONSTITUTION:An auxiliary rod 10 is inserted into the hole 9 of a hollow rod 11. The auxiliary rod 10 is about one quarter - half as long as the hollow rod 11, and is interposed in such a manner that the end surface thereof coincides with the end surface of the hollow rod 11. The hollow rod 11 is forged between an upper mold 12 shaped in such a manner as to form an outer peripheral portion 8 and a lower mold 13 provided with a tooth form portion 14 for forming a rack tooth 4 to complete a rack shaft 1. |
