| 摘要 |
<p>A method of manufacturing a ring-shaped metallic latch plate (11) having internal ratchet teeth (20) on the inner peripheral surface thereof using a punch (30) having a forging tooth-shaped edge (31) for forming the internal ratchet teeth and a pilot (32) provided at the axially forward side of the edge, comprising the steps of first forming a prepared hole (12) in the metallic latch plate (11), disposing the punch (30) so that the pilot (32) is aligned with the prepared hole (12) so as to engage the forging tooth-shaped edge (31) with the peripheral edge part (13) of the prepared hole (12), and then driving the forging tooth-shaped edge (31) so that the peripheral edge part (13) is extruded by cold forging so as to form the internal ratchet teeth (20) around the periphery of the prepared hole.</p> |
