GB895860A - Cooking vessel and method of making the same - Google Patents

Abstract

895,860. Making cooking vessels; composite casting. SUNBEAM CORPORATION. Nov. 24, 1958 [March 25, 1958], No. 37788/58. Classes 83 (1) and 83 (2). [Also in Groups XI and XVII] A cooking vessel is provided with an inner cooking wall surface 20 made of a relatively hard material of relatively poor heat conductivity, an exterior layer 24 of an aluminium containing material which is an excellent heat conductor but which cannot readily be metallurgically bonded, i.e. with surface alloying, to the hard material and an intermediate layer 21 consisting of a third material disposed between and forming a good metallurgical bond with both of the two materials and the vessel includes a heating element 13 embedded in the exterior layer. The vessel has, in an embodiment, an electric heating element 13 embedded in the bottom thereof, a handle 12, insulating support legs 17 and a plug receptacle 16 for a power supply and possibly a temperature control device. In making the vessel a composite sheet formed of a sheet of stainless steel 20, 7-12 thousandths of an inch thick, rollbonded or brazed to a sheet of copper 21, 6 thousandths of an inch thick, is deformed to form the body of the vessel with the stainlesssteel on the interior. The copper is cleaned in acid, possibly after abrading, and the composite sheet is placed in a mould 25, 26 in the upper part 26 of which a sheathed heating element 13 is suspended. Aluminium or aluminium alloy is supplied to the mould in a gravity die casting process at a temperature of 1200-1500‹ F. or in a pressure die-casting process at a temperature of 1150-1400‹ F., the dies in this case being initially heated to 500- 650‹ F. to heat the composite sheet. The aluminium layer 24 cast on to the copper of the sheet may have a thickness of #th inch. The mould may include recesses such that integral cast leg supports are provided or tapped leg supports may be placed on the copper surface and secured in position by the cast metal. Alternatively, the cast aluminium may be drilled and tapped to receive the legs. An alluminium alloy containing Cu, Fe, Si, Mn, Zn, Ni, Sn and Mg may be used. The stainlesssteel may be replaced by titanium &c. and the copper by another metal.