| 摘要 |
According to a method of manufacturing a hollow rack shaft, an approximately rectangular plate having a wide rack tooth portion is bent lengthwise. At this time, the plate has, at the central portion, a flat bottom portion on which rack teeth are formed later and a pair of mutually facing leg portions, and, in the vicinity of both ends, a semicircular bottom portion and a pair of mutually facing leg portions. The mutually facing leg portions at the central portion are bent into a gutter-like cross section having a larger clearance than the clearance of the mutually facing leg portions in the vicinity of both ends. The rack teeth are thus formed on the flat bottom portion through the plastic flow of the flat bottom portion and a part of material of the pair of leg portions of this flat bottom portion. The plate on which the rack teeth have been formed is formed into a tube having a hollow inner surface, by bending the plate and butt-joining the edge portions. <IMAGE> <IMAGE> |
