Can components having a metal-plastic-metal structure
OwnerRobert J. McHenry, Dominique Petitinventors
Life of this patent
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Abstract
The invention concerns components of food cans (1), can bodies (6), and ends fabricated starting from a stratified construction constituted by a foil of plastic material on each of the faces of which adheres a metal foil and their fabrication process. The components are characterized by the nature of the material, metal-polymer-metal construction and by the fact that ratio of the plastic thickness to the sum of the metal thicknesses is greater than 0.5. The fabrication process is drawing in one or several passes characterized preferably by the particular shape of the punch and of the die plates. The invention applies equally to the fabrication of food cans as to ends for food cans or for beverage cans.
Claims18
A finished can body comprising an upstanding sidewall obtained by drawing a metal-polymer-metal structure M.sub.i -P-M.sub.e, wherein P is an essentially non-oriented thermoplastic polymer layer and M.sub.i and M.sub.e are interior and exterior metal foil layers, respectively, said sidewall having an upper rolled region wherein the sidewall is rolled outwardly such that the M.sub.i layer is in extension and is ruptured at a location where a radius of curvature of the rolled region is smallest.
A method of making a drawn can body comprising the steps of:
- a) preparing a strip having a metal-polymer-metal structure M.sub.l -P-M.sub.e, wherein P is an essentially non-oriented thermoplastic polymer layer and M.sub.l and M.sub.e are each metal foil layers and wherein a ratio of relative thicknesses before drawing and ironing of P/(M.sub.l +M.sub.e), is greater than about 0.5;
- b) cutting a disc from the strip;
- and
- c) drawing the disc to form a can body in one or more successive passes.
A method for making a drawn can end comprising the steps of:
- a) preparing a strip having a metal-polymer-metal structure M.sub.i -P-M.sub.e, wherein P is an essentially non-oriented thermoplastic polymer layer and M.sub.i and M.sub.e are each metal foil layers and wherein a ratio of relative thicknesses of P/(M.sub.l +M.sub.e), is greater than about 0.5;
- b) cutting a disc from the strip;
- and
- c) drawing the disc to form a can end in a single pass.
A method for making a drawn can body comprising the steps of:
- a) preparing a strip having a metal-polymer-metal structure M.sub.l -P-M.sub.e, wherein P is an essentially non-oriented thermoplastic polymer layer having a thickness of from about 100 to about 500 microns and M.sub.l and M.sub.e are each metal foil layers each having a thickness of from about 25 to about 150 microns and wherein a ratio of relative thicknesses of P/(M.sub.l +M.sub.e), is greater than about 0.5;
- b) cutting a disc from the strip;
- and
- c) drawing the disc to form a can body in one or more successive passes.
Dependencies are inferred from the claim text.