New technology for fabricating a one-piece cup-shaped can body having a protective organic coating as formed. Such can body is formed free of side wall ironing from can stock comprising flat-rolled sheet metal substrate precoated with protective organic coating and forming lubricant. A plurality of successive diameter-reduction operations are carried out on a planar blank and cup-shaped work product under tension during which side wall height is increased and side wall substrate is decreased in thickness to provide controlled uniformity in side wall substrate thickness over about 85% to about 95% of side wall height for such can body. The fabricating tooling provides for a preselected clearance between a punch peripheral wall and a die cavity internal wall in each of such plurality of diameter-reduction operations to achieve a desired decrease in side wall thickness as the precoated substrate is moved into a die cavity by relative movement of its respective punch.
This application is a continuation in part of copending U.S. application Ser. No. 831,624, now U.S. Pat. No. 5,014,536, "Drawn Can Body Methods, Apparatus and Products" filed by the present applicant Feb. 21, 1986, which was a continuation in part of U.S. application Ser. No. 712,238, "Drawn Can Body Methods, Apparatus and Products" filed Mar. 15, 1985 (now abandoned) and Copending U.S. application Ser. No. 07/573,548, now U.S. Pat. No. 5,119,657 entitled "Draw-Process Methods, Systems and Tooling for Fabricating One-Piece Can Bodies" filed by the present applicant on Aug. 27, 1990.
A bottom forming station for forming a metal can having a sidewall and base portion is provided. The bottom forming station comprises a punch sleeve. The punch sleeve comprises a body having a sidewall that defines a bore for securely receiving a punch nose. The punch sleeve sidewall has a first section that corresponds to the shape of at least a portion of a beverage can base. The punch sleeve sidewall has a second section that corresponds to at least a portion of a beverage can sidewall profile. The second surface is integrally coupled with the first surface. The punch sleeve sidewall has a third section that is adapted to communicate with a punch nose and form a slip line that has a junction area in a non-active area. The third section is integrally coupled with the first and second sections. A bottom forming station also comprises a punch nose. The punch nose includes a body having a sidewall. The sidewall has a first section that corresponds to the shape of at least a portion of a beverage can base. The punch nose sidewall has a second section that is integrally coupled with the first section. The punch nose is mechanically coupled within the bore of the punch sleeve with the second surface of the punch nose in communication with the third section of the punch sleeve sidewall such that a slip line is formed with a junction area in a non-active area.
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.
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. 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.
