GB1422707A - Production of sheet steel containers - Google Patents

Abstract

1422707 Making sheet steel containers; cupping K M ENG AG 12 Feb 1973 [11 Feb 1972] 6834/73 Headings B3A and B3Q A method of making a sheet steel container from a deep drawn cup-shaped sheet steel blank comprises subjecting the cup-shaped blank to a series of forming steps, each comprising simultaneously deep-drawing and ironing the blank by forcing it through a single annular deepdrawing and ironing die with a punch member 32 within the blank. Blanks (2), Fig. 1 (not shown), are subjected to a series of deep-drawing operations in separate assemblies to form successively cup-shaped blanks (8a) to (8g), Figs. 2 to 8 (not shown), followed by piercing of the bottom of the cup-shaped blank, which is then necked, and the necked part curled. Alternatively the bottom of the blank may be domed inwardly, Fig. 17. A blank 8i is placed inside a stretch ring 13 and is supported on an ejector 16. Lubricant and/or coolant is supplied either through conduits 44 in a stripper member 45 or through conduits in a ring member 41. The latter conduits are directed at an angle α, which may lie between 0-90 degrees with reference to a punch member 14. Lubricant conduits 46 may also be provided in the stretch ring 16. The punch 14 has a central passage 18 for return of lubricant supplied to the interior of the blank. A number of stretch forming operations are performed, in which the cupshaped blank is formed to the required height, while its walls are reduced in thickness. The portion 20 of the blank, which does not pass through the stretch rings, is bent and trimmed to form a flange 29, Fig. 20. The blank is placed in a die member 30 and a resilient member 35 is located on a punch member 32 inside the blank. A pressure stamp 36 is driven downwardly to expand the member 35 radially outwardly thereby forming a smooth outer surface to the side wall. The deep-drawing and stretch forming operations are performed simultaneously on a plurality of blanks, each blank being passed through each working stage in succession. The piercing and curling of the necked part of the blank may take place after stretch forming. In an alternative method, the sheet steel blanks are cut in joined pairs which are separated and then the pairs deep drawn and stretch formed together. The deep-drawing operations may be performed in two stages, the direction of drawing being reversed for the second stage, Figs. 22, 23 (not shown).