Patent GB-826883-A (GB)
Title: Improvements in or relating to metal cans
IPC: B21D51/26
Filed: 1957-10-24
Abstract: 826,883. Making containers; rolling; stamping; angular bending; casting composite ingots. VALYI, E. I. Oct. 24, 1957 [Nov. 9, 1956], No. 33305/57. Classes 83 (1), 83 (2) and 83 (4). [Also in Group XVII] In a method of making a metal can, from a flat sheet, having walls separated by a narrow slit in selected areas only, and integrally joined in other fin-forming areas, the walls are separated to form a body having integral longitudinal fins, and an end-closure member is attached. An ingot 10 having weld-preventing inserts 12 is rolled to form a flat sheet 20 having spaced longitudinal areas of stop-weld defining slits 23 separating the walls 21, 22, and having integrally united fin-forming areas between. The inserts are held in place during casting by recesses in the mould. Alternatively, the ingot may be formed with holes, e.g. rectangular, which are filled with weld-preventing material, e.g. talc for an aluminium ingot, silica or graphiet powder for copper or copper-alloy ingots, or silica, mica or boron nitride for a steel ingot, or again the holes may be surfaced with aluminium oxide by chemical treatment. If the grain structure requires rolling in more than one direction during reduction of the ingot, crossrolling must be in a direction perpendicular to the longitudinal axis of the web. The web 20 may alternatively be made by rolling superimposed plates with stop-weld sprayed, painted or printed between. Individual can blanks, Fig. 5 (not shown), may be cut directly from the web 20, or alternatively longitudinal strips, one blank wide, or multi-blank widths, one blank long may be produced by severing along the lines 25, 27 respectively. The individual blanks are then partially or wholly expanded by hydraulic pressure or air jets, and if partially expanded, the circular can body, or other desired form, is finally shaped by a tapered mandrel 31, Fig. 7, over which it is guided by feed rollers. Inward lateral pressure may be applied, in which case the mandrel need not fully correspond to the finished shape of the cam body. Integral ribs 32 are trimmed before or after partial expansion of the body, and are finally turned in against the side of the completed can body or crushed flat by coacting rollers on the mandrel 31 and outside the can body. Fig. 9 (not shown). Alternatively, after partial expansion by fluid pressure sufficient to admit a roller 38, Fig. 10, the can body is finally shaped by rollers 38, 39. A strip of blanks may be expanded to form a seamless tube with integral longitudinal fins, and individual bodies separated afterwards, or can blanks may be separated before expansion. A strip of blanks may also be partially inflated before separation into individual blanks. The can-blanks are mitred at the corners and outwardly flanged to receive similarly flanged closure members, which are secured by folding, seaming, crimping, &c. In a modification, a two-compartment can is made from a casting having double layers of stop-weld inserts, so that an intermediate wall is formed between the layers. U.S.A. Specifications 2,375,334 and 2,690,002 are referred to.