Apparatus for draw-processing, free of sidewall ironing, precoated sheet metal can stock into a precoated one-piece cylindrical-configuration cup-shaped work product, comprising, in combination,
- means for supplying circular-configuration cut blanks of precoated planar can stock consisting essentially of flat-rolled sheet metal substrate of preselected starting thickness gauge which has been prepared for and precoated on both planar surfaces of the substrate with a surface coating, including an organic polymeric coating and draw-processing lubricant for each such can stock surface, cupping press means, including draw-forming tooling means,
- which move coaxially in relation to a centrally-located axis to provide for draw-forming the precoated cut blank, free of sidewall ironing, to form a one-piece cup-shaped work product,
- the one-piece cup-shaped work product including
- a centrally-located axis which coincides with the centrally-located axis of the tooling during fabrication of such work product,
- a substantially-planar closed endwall of circular configuration in plan view disposed such that the centrally-located axis intersects the circular configuration endwall in perpendicular relationship to the geometric center of such endwall,
- a cylindrical-configuration sidewall, which is symmetrically disposed with respect to and uniformly spaced from the centrally-located axis, defining an open end for the cup-shaped work product,
- a unitary juncture between the planar endwall and cylindrical sidewall, the unitary juncture having a curved configuration as viewed in cross section in a plane which is defined by including the centrally-located axis, and
- a can body flange extending around substantially the full perimeter at the open end of the cup-shaped work product as drawn, the flange being oriented radially-outwardly in a plane which is in substantially perpendicular transverse relationship to the centrally-located axis so as to provide a uniform sidewall height between such open end flange and the unitary juncture of the cup-shaped work product, with
- substrate of the closed endwall, between its geometric center and the unitary juncture, having a thickness gauge substantially equal to the preselected starting gauge for the flat-rolled sheet metal substrate as supplied, and
- sidewall substrate which is free of an increase in thickness gauge above such preselected starting gauge throughout the height of the sidewall from a location contiguous to the unitary juncture to a location contiguous to the flange at the open end of the cup-shaped work product;
- the draw-forming tooling means, including
- (a) a cupping die presenting:
- (i) an internal wall defining a die cavity having a
- circular configuration in a plane which is perpendicularly transverse to the centrally-located axis,
- (ii) a curved surface, as viewed in cross section in a
- plane which is defined by including such centrally-located axis, defining an entrance zone into such die cavity,
- the cupping die cavity entrance zone presenting a curvilinear configuration surface about which such coated substrate is drawn into such cavity,
- such cupping die entrance zone, as projected onto a plane which is perpendicularly-transverse to such centrally-located axis, having a radial dimension within a range which exceeds such predetermined starting thickness gauge but is less than about five times such starting gauge, and
- (iii) a planar clamping surface in substantially perpendicular transverse relationship to such centrally-located axis circumscribing the cavity entrance zone;
- (b) a cupping punch presenting:
- (i) an endwall for forming an endwall for such work product,
- such work product endwall having a substantially-planar configuration portion disposed in substantially perpendicular transverse relationship to such centrally-located axis,
- (ii) a cylindrical sidewall, symmetrically-disposed with relation to such centrally-located axis, and
- (iii) a unitary juncture, extending between such punch endwall and punch sidewall, having a curvilinear configuration surface as viewed in cross section in a plane which includes such centrally-located axis,
- such unitary juncture curvilinear-configuration surface, as projected onto such perpendicularly-transverse plane, having a radial dimension in a range of about twenty-five times to about forty times such substrate starting thickness gauge,
- the cupping punch being disposed for coaxial relative movement into, and from, the cupping die cavity;
- and
- (c) a clamping element circumscribing the cupping punch, the clamping element presenting:
- (i) a planar clamping surface in substantially perpendicular transverse relationship to such centrally-located axis for coacting with the planar clamping surface of the cupping die for clamping pre-coated planar can stock between such planar clamping surfaces, and
- (ii) an interior sidewall of cylindrical-configuration circumscribing the cupping punch.