容器の冷間押出し加工における偏肉 : 第4報, 初期偏心およびポンチ先端形状の影響

概要

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Deviation of punch load center from the punch center, lateral force exerted on the punch head and eccentricity between punch and die are measured through the forward cup extrusion. When an initial eccentricity exists between the punch and die, lateral force initiates and bends the punch toward the die center ; then the eccentricity of the cup decreases with increase in punch penetration. This centripetence appears when both initial eccentricity and extrusion ratio are large. Conversely, when both initial eccentricity and extrusion ratio are small, the eccentricity induced by some disturbances increases with punch penetration. A coned punch surpasses a flat-ended punch in the centripetence, but is apt to become unstable as the process proceeds. A frustum-headed punch is concluded to be the most stable. An increase in the land length stabilizes the punch but tends to lead to galling. Unbalanced friction and the oblique end of the blank cause larger eccentricity for the coned punch than for the previously reported flat-ended punch.
1993-02-25