| 摘要 |
PROBLEM TO BE SOLVED: To uniformly form a tooth width of a tooth part for forming a rack in a sufficient width over the axial direction.SOLUTION: A hollow rack bar manufacturing method comprises a heating step of heating a central part in the axial direction of a pipe material P of a predetermined area K to 450°C or higher by a high frequency, a press step of molding a processing wall part Pa by executing flatly crushing processing on the predetermined area K, a holding step of holding the pipe material P while pressing a denture mold 53 corresponding to a rack Pb to the predetermined area K and a press-in step of forming the rack Pb corresponding to the denture mold 53 by making the processing wall part Pa contacted with the denture mold 53 plastically flow to the outside from the inside of the pipe material P by pressing a mandrel M inside the pipe material P. |
