| 摘要 |
PROBLEM TO BE SOLVED: To hardly cause damage such as a crack on a metal plate when the metal plate is folded back in order to manufacture a pair of flange parts to thereby enable adoption of a titanium plate material in comparison with prior art, and further to improve a degree of freedom in design for obtaining a yoke having high strength and high rigidity.SOLUTION: A pair of recessed grooves 27, 27 is formed on portions positioned inside with respect to a folding-back direction for constituting both flange parts respectively at two positions near both ends in the longitudinal direction of a base end side plate part 20a of an intermediate raw material, over the whole width of the base end side plate part 20a. Then, portions near both ends in the longitudinal direction of the base end side plate part 20a are folded back at both recessed grooves 27, 27, to thereby form both flange parts. |
