| 摘要 |
PURPOSE:To efficiently manufacture a starter yoke having excellent mechanical strength by forming a magnetically shielding groove by the pressing pressure of a roller. CONSTITUTION:A pressure receiving anvil 9 is inserted into the central hole of a cylindrical yoke 7 made of soft iron. A work which forms a magnetically shielding groove 8 on the outer peripheral surface of the yoke 7 presses a roller 6 from the outer peripheral surface of the yoke 7 toward an axial center, and rolling the roller 6 in this state. The roller 6 has a structure that a disc of superhardness is rotatably journaled at the center, and is accordingly pressed to the outer peripheral surface of the yoke 7, thereby allowing the peripheral wall of the yoke 7 to hole it between the roller and the anvils 9, and forming the groove 8 having V-shaped cross section. |
