| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a hollow tie rod which can thoroughly reduce the weight of the hollow tie rod, improve the productivity, and realize the excellent mechanical strength of a coupling portion with a rack shaft. SOLUTION: The manufacturing method of the hollow tie rod having a hollow shaft portion and a spherical portion formed on one end of the shaft portion comprises an upset forging step forming a solid portion 50a on one end of a straight metal pipe 50 cut in a predetermined length, a hot forging step forging the solid portion 50a to a bulged portion 50b partly having a spherical surface 50b1 and a machining step of machining the bulged portion 50b into the spherical portion. The shaft portion of the hollow tie rod is formed in the substantially same wall thickness, and the weight thereof is thoroughly reduced compared with a conventional product, and the drilling step of the shaft portion can be dispensed with, and thus, the manufacturing time is shortened, and the productivity improved. In addition, the bulged portion 50b formed by the hot forging the spherical surface 50b1, and thus, the metal flow line of the spherical portions which are subsequently machined is not cut even by the machining, and the mechanical strength is also excellent.
|
