Patent GB-931831-A (GB)
Title: Improvements in and relating to the production of tubular metal bodies
IPC: B21D51/26
Filed: 1960-02-17
Abstract: 931,831. Making cans etc.; breaking; rolling. CONTINENTAL CAN CO. Inc. Feb. 17, 1960 [Feb. 18, 1959; Jan. 15, 1960], No. 5561/60. Classes 83 (2) and 83 (4). A can &c. is made by placing a hollow metal core 12 between metal slabs 10, 11, welding the parts together, sealing the core at one end and filling it with stopweld, heating the assembly and rolling it to bond the parts and form a strip, and opening the strip to form a tubular body. The core and slabs may be of the same or different metals; the cores may be of stainless steel or titanium and the slabs of mild steel, or cores of aluminium may be used with slabs of aluminium, aluminium alloy or brass. Cores of copper may be used with slabs of brass or aluminium. Slabs and cores of mild steel and stainless steel are also referred to. As shown, a number of cores formed from flattened tubes with the stopweld passages 23 trued by a tool 20, Fig. 6, and the edges milled square and coated with stopweld, e.g. carbon or a slurry of alumina, zirconia, or talc dried or flame-sprayed thereon, are compacted between edges 13a of the slabs or separate fillers, and the parts secured by welding 15, 16. Before assembly, the inner surfaces of the slabs and fillers, or the faces of the cores, or both, may be treated with material for assisting the roll-bonding operation, e.g. stainless steel and titanium cores may be nickel-plated and cores of mild steel or stainless steel may be coated with zinc. Wedges 30 and welding 31 seal the stopweld passages 23. To compensate for differential lateral spreading during rolling, slots 36, Fig. 12, may be milled in one or both slabs adjacent stopweld location marks 19, or the profile of the top and bottom of the blank may be milled as in Fig. 10, or the blank may be both slotted and profiled. The slabs may be pre-cast to the approximate profile. Towards the edges of the slabs, the grooves 36 are displaced by greater distances from the respective layers of stopweld 27 separating the cores 12. The groove-areas are increased towards the slab edges by increasing the angle of the grooves, or their depth, or both. One or both sides of the grooves are coated with stopweld 50 to provide lines of weakness which are perpendicular in the rolled strip if the median planes 51, 52 of the grooves are disposed at steeper angles to the vertical the further the grooves are from the centre of the slab. Stopweld powder, strip or fluid is inserted in the passages 23 (Fig. 14, not shown) before these are sealed by wedges and welding for the rolling operation. The stopweld for aluminium or aluminium alloy may be sodium chloride, epoxy resin, polyethylene, polypropylene, polycarbonate, polyamide (nylon), polyester (e.g. terephthalic or isophthalic glycol ester polymer resin), silicone, navolak, phenolic resin, cyclic polyhydrocarbon, polymethyl styrene resins, iron or aluminium stearate. The assembly may be heated to the melting point of the stopweld before inserting the stopweld. For copper assemblies, the sodium chloride or organic stopwelds may be used, or graphite, talc, alumina, or other non-melting powder. The assembly may be vibrated during filling with stopweld powder. For mild steel, a high melting-point salt such as barium chloride may be used, or one of the non- melting powders. For stainless-steel and titanium, a high melting-point salt may be used as the stopweld. Zirconia may be used as a stopweld. The assembly B, Fig. 15, is preheated before being hot-rolled, annealed and cold-rolled. The strip-margins 65, Fig. 17, are removed along the lines of weakness 60 by deflection around rolls 66, the strip being coiled at 67 or fed to cleaning brushes 70, Fig. 16, and then to a guillotine 71. The multiple blanks R may then be decorated on both sides, as by printing-plates 74, 79, before being baked in an oven 85. Rolls or cutters 88 may sever the strips S<SP>1</SP>-S<SP>4</SP> from each other, and a guillotine 89 cuts the strips into single blanks. Instead of severing by rolls 88, the blanks R may be flexed along the lines of weakness, as by rolls 93, Fig. 19, which may have belts 94. The blanks are then opened or expanded, the projecting fins being trimmed before or after opening the blank and reduced by hammering (Fig. 24, not shown). The can interiors may be sprayed with an organic enamel, which keys with the embedded alumina, zirconia &c. stopweld particles, and baked to eliminate the enamel solvent. If an organic stopweld is used, the solvent of which is also the solvent of the enamel, the enamel after baking is a composite of the resin of the stopweld and that of the enamel. Blank and strip sizes are given. Flanges may be provided for seaming to the ends of the can.