FORMING CUP-SHAPED PRODUCTS HAVING INTERNAL GEARS

摘要

A cup-shaped raw workpiece having a bottom panel and a cylindrically-shaped circumferential panel is positioned facing downwardly on a movable lower punch having a forming gear profile. The lower punch is provided in a die having an orifice portion which together with the gear profile defines an orifice. A resilient mechanism resists downward movement of the lower punch. An upper punch is lowered to hold the bottom panel of the workpiece against the lower punch and pushes the workpiece to extrusion form the inner surface thereof through the orifice. An escape groove for excess metal can be provided in the bottom inside corner of the workpiece at the juncture of the circumferential panel and the bottom panel. The lower punch can be provided with an upwardly extending protrusion near the outer circumferential edge of the upper end surface thereof which has an outer chamfered circumferential edge.