| 摘要 |
PURPOSE:To reduce a cutting margine at a succeeding work and to obtain an accurate thin cup, by thinning an uneven end face part of an open end of a cup-shaped rough shape material by forming a drawing hollow with a punch, then by cutting uniformly from the hollow part. CONSTITUTION:The cup-shaped rough shape material 2 formed by cold extruding is throttled in its outer diameter through a drawing die 5 by descending a punch 6, the drawing hollow is formed by the punch 6 on an inner surface of the uneven end part to be thinned. Its thinned fin part 3a is pushed to open to an expanding part 5a of the drawing die 5 to open. More, when the punch is advanced, a tension works between the die and the punch to cut the fin part 3a, at its bottom surface, a coining is performed by the punch 6 and knockout 7. As to the obtained thin cup 3 by this way, the uneven end part at the open end is removed, the cutting margin L2 at the succeeding work is reduced and is made as an accurate thin cup. Thus the reduction of required cutting time and the elongation of the life of cutting tool are performed.
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