Patent GB-1369879-A (GB)
Title: Exploxive welding process
IPC: B23K20/08
Filed: 1971-12-09
Abstract: 1369879 Welding by pressure NIPPON YUSHI KK and SHOWA DENKO KK 9 Dec 1971 [15 Dec 1970 (2)] 57241/71 Heading B3R In an explosive welding process for cladding a base metal sheet the cladding sheet 3 is disposed spaced from the base sheet 4 by one twentieth to twenty five times the thickness of the one sheet which is to be driven towards the other, a protective bond-preventing layer 6 is coated on the outer surface of the one sheet, a driver plate 5 is arranged to face the protective layer at a spacing therefrom of one twentieth to twentyfive times the thickness of the driver plate and an explosive layer 2 is formed on the outer surface of the driver plate. On detonation of the explosive layer 2 the driver plate collides with the driven plate at a collision propagation velocity sufficient to provide a collision propagating velocity between the cladding sheet and the base metal sheet faster than 800 m/sec. but slower than the fastest sonic velocity in the cladding and base metal sheets. The driver, cladding and base metal sheets 5, 3, 4 may be parallel and/or inclined and detonation of the explosive layer on the driver plate may be by means of a detonator, linear wave generator or by means of a detonating driver plate 8, Fig. 8, itself having an initiator explosive layer 7. The detonator driver plate may be inclined to the driver plate and is preferably provided with an explosive layer having a higher explosive velocity than the driver plate in order to provide an explosion wave front on the latter inclined so as to face downwards at an angle not exceeding 60 degrees. The driver plate 5 may be used to drive the base metal sheet rather than, as shown, the cladding sheet, and the process is not limited to one cladding sheet, e.g. two cladding sheets may be disposed between the driver and base metal sheets or sandwich the base metal sheet (Example 4). Metals referred to which may be bonded include mild steel, titanium, stainless steel, Hastelloy (Registered Trade Mark), brass, bronze, copper, zirconium, nickel, tantalum, silver, gold, platinum, tungsten, niobium, chromium, cobalt, aluminium, molybdenum, magnesium, vanadium, zinc, tin, and their alloys. The protective layer may be of rubber, synthetic resin, paint, water or gelated product of gelatine or agar or a mixture thereof. A foamed rubber or synthetic resin may fill the spacing between the driver plate and protective layer so as to maintain the desired spacing and inclination of the plates. The protective layer may also be tapered to provide varying time delays in the delivery of the collision impact of the driver plate to the cladding metal sheet. The driver plate is normally of aluminium or steel with or without coating of metallic or resin material. Other suitable though more expensive materials are referred to. The spacing means may be small pieces of foamed rubber or foamed synthetic resin, wooden or metallic blocks. Reference is made in the examples given to the use of aluminium cube spacers and L-shaped spacers. Explosive mixtures referred to include: 10 parts tetranitromethylaniline with 90 parts ammonium perchlorate; 75 parts trinitrotrimethylenetriamine with 25 parts synthetic resin paste; 2 parts tetranitromethylaniline with 98 parts ammonium perchlorate used in conjunction with an initiator layer of 20 parts/80 parts of the same constituents.