| 摘要 |
<p>A method of manufacturing a part having an undercut, which is formed to have a predetermined diameter, in a simple way without the use of any split pattern. A stock material for a material (50a) being worked, disposed above a tapered portion (53) of the material (50a) is subjected to swaging by pressing of a sleeve punch (20). Simultaneously, the stock material for the material (50a) disposed in the vicinity of the tapered portion (53) is subjected toironing by a shoulder (12) of a die (10) to undergo bulging deformation. The stock material for the material (50a) disposed in the vicinity of the tapered portion (53) flows toward the axis of the material (50a) to be drawn diametrically until it abuts against the outer wall of a mandrel (30), and a hole (52) of the material (50a) is gently tapered to be reduced in diameter to have a diameter (d2). The stock material for the material (50a) in a range (L3) disposed below the tapered portion (53) of the material (50a) is not reduced in diameter owing to forward extrusion, and is extruded forward to form a blind hole (42) in the form of an undercut having a depth (L4) which corresponds to a depth (L3).</p> |
