| 摘要 |
PROBLEM TO BE SOLVED: To provide a sheet metal arm member having high contact safety to a human body and high quality. SOLUTION: An arm member is constituted so that the cross sectional shape of an arm part 2C is roughly quadratic and joining parts 2D at sheet metal edges are arranged along the longitudinal direction of the arm part 2C. Bent edge parts 2E, 2E positioned to both sides of the joining parts 2D are respectively bent at a sharp angle taking bending guide grooves 2F, 2F as a start point. Further, by the pair of the bending edge parts 2E, 2E, a recessed face having the joining part 2D of the sheet metal as a center is formed to the peripheral face of the arm part 2C.
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