GB956710A - Manufacture of food container and the like from aluminum foil or other thin metallic material - Google Patents

Abstract

956,710. Making food containers. REYNOLDS METALS CO. Aug. 8, 1960, No. 27452/60. Headings B3A and B3Q. [Also in Division B8] A method of making a food container from aluminium or aluminium alloy sheet material 0.0015 to 0.006 inches in thickness comprises the steps of simultaneously embossing and work hardening the sheet with a pattern of closely adjacent undulations which cause the .sheet to have an apparent thickness of 130- 200% of the un-embossed material and forming said sheet into a container. Fig. 1 shows the type of pattern 22 produced on a sheet 20, on the scale 21 shown under the Figure the distance D represents 0.5 inch. The material is rolled between rolls 26 (Fig. 13) annealed in a furnace 30, further reduced if desired by rolls 34 and then embossed by rolls 36 which may comprise two rigid co-operating rolls, or one rigid roll and one resilient roll. The stiffness of the embossed material is such that the thickness of the stock used may be reduced by 0.0005 to 0.001 inch while retaining the strength of a container made from plain sheet. The drawing characteristics of the material are improved by the extra material available for forming at sharp corners and by the more even tension maintained on the material by the pressure plates of the forming die since the increased apparent thickness of the material reduces the effect of variations in thickness of the plain sheet. Fig. 5 shows a dish 76 which has edges flanged at 90 and beaded at 88, and stiffening grooves 80, 82, 84 formed in the bottom. In view of the increased stiffness of the formed material these grooves may be omitted. In a modification only the bottom of such a dish is embossed, either by embossing selected area of the sheet from which the dish is made or by embossing the material in the forming die. Figs. 7 and 9 show a container 92 which has integral partitions 98 and 100 and edges which are flanged at 104 and beaded at 102. Fig. 10 shows a press tool 120 comprising a punch 122 and die 124 and pressure plate assemblies 134, 136, 138 and 140. The member 138 is stopped by the ring 146 before the bottom of the stroke and the flange 90 or 104 is produced by the members 134 and 138. The bead 88 or 102 is formed by the ring cavities 148 and 150 on the return stroke of the tool. The article is ejected by a knockout 160.