Patent GB-1433632-A (GB)
Title: Welding of explosively plated metal sheets
IPC: B23K9/23
Filed: 1973-05-23
Abstract: 1433632 Welding by fusion and pressure DYNAMIT NOBEL AG 23 May 1973 [31 May 1972] 24693/73 Heading B3R A method of joining two members one of which is an explosively plated sheet comprising a substrate metal sheet and a plating metal sheet and which has been produced by providing explosive material on the plating sheet, spacing the sheets and driving the plating sheet towards the substrate sheet by detonation of the explosive material, at least one area of the plating sheet not being backed by substrate metal, the substrate metal having been removed from beneath an area of plating sheet not bonded or not directly bonded to the substrate metal or not having been present for bonding, and the other member of which is a said explosively plated sheet or a metal member in the shape of a body of revolution, comprises forming a weld between the two members in a said area of the or each one member, in the case of the body of revolution the body being passed through an opening in the said area of the one member. The plating sheet may be larger than the substrate sheet and the explosive layer restricted to an area equal to that of the substrate sheet so that after detonation the plating sheet over-hangs the substrate sheet to which it is bonded. The plating sheet may be of the same size as the substrate sheet but the explosive in this case will only cover those areas where bonding is to be effected or alternatively the explosive layer may cover the whole of the plating sheet but bond preventing material arranged between the sheets where bonding or direct bonding is not desired. The material may be arranged on one or both of the sheets. Such material for preventing direct bonding may be low melting metal, e.g. tin or woods alloy, which can be melted out after explosive bonding is effected, in strip or electro- or chemical deposited form, wax, viscous grease, paper, synthetic plastics, e.g. contact adhesives, or polyvinyl chloride, polyethylene or polytetrafluoroethylene, metal oxide, e.g. oxide of the substrate and/or plating metal, aluminium oxide or zinc oxide, a low melting glass or borax applied as a melt. The regions of the non- bonded plating layer near the edge are, after explosive bonding, raised and the substrate layer machined by milling, sawing, burning, planing, turning &c. or when the non-bonded region is spaced from the edges the plating sheet is drilled, turned &c. to provide a hole before the substrate layer is machined. Alternatively the plating layer may be provided with a hole before bonding and the substrate layer with a larger hole. Plated sheets 7, 8, Fig. 3, wherein the plating sheet 2 is larger than the substrate sheet 1 are welded by bending down the plating sheets 2 and welding then by a seam 9 and a further seam 10. A strip 12 is then welded to the substrate sheets 1 by fillet welds 11. Plated sheets wherein the plating sheet is of the same size as the substrate sheet, Fig. 4a, are prepared by machining the ends of the substrate sheets 1 and bending up the ends 6 of the plating sheets 2. The sheets 1 are welded by a seam 13 and the ends 6, are brought together and seam welded at 9, Fig. 4b. Alternatively the ends of the plating layers are bent flat and welded to a bimetallic strip beneath them in the gap between the machined ends of the substrate sheets. The bimetallic strip is then welded, using a TIG argon shielded process, to the machined ends of the substrate sheets also using argon on the substrate side. Where the non-bonded region is spaced from the edges of the sheets a pipe 16, Fig. 6, is inserted through a hole 17 provided in the sheet 1 and into contact with the bent up sheet 2, a weld 9 being provided between the sheet 2 and the pipe 16.