Draw-processing of can bodies for sanitary can packs

摘要

Draw processing flat-rolled sheet metal substrate preselectively precoated on each surface with organic coating and draw lubricant into one-piece can bodies ready for assembly into sanitary can packs free of any requirement for applying organic coating or adding organic coating for repair purposes after fabrication and before such direct usage. Cupping of precoated flat-rolled sheet metal can stock using preselected tooling configurations and clearance avoids any increase in side wall metal thickness gage. Tension elongation during redraw is controlled over side wall height by clamping solely between planar clamping surfaces, tooling configurations and preselected clearances to decrease thickness gage uniformly over side wall height between flange metal open end of can body and curved transition zone at closed end. High production rate blanking and cupping is achieved with out-of-phase simultaneous movement of cupping die and punch which provides for rapid discharge cup-shaped work product, open-end-down on flange at open end of cup. Surface area of the cavity entrance zone for each die is fabricated about multiple radii forming sharp edge about which coated can stock is drawn into each die cavity. Curved surface transition zone for each punch is maintained large in relation to sheet metal substrate starting gage which facilitates change of configuration of metal from planar state into cylindrical side wall.