GB1171295A - Improvements in Diecasting - Google Patents

Abstract

1,171,295. Die-casting. ASSOCIATED ENG. Ltd. 23 Nov., 1966 [25 Nov., 1965], No. 50227/65. Heading B3F. In a method of low pressure die-casting molten metal 2 is transferred from a crucible 1 into a die 33 by using a pressure vessel 3 partly submerged in the molten metal 2 and having a valve 20, 21 in its bottom to allow equalization of the level of the molten metal inside and outside of the vessel 3 and a means for creating a higher pressure in the vessel above the molten metal relative to the pressure within the die so that molten metal is passed via a heated transfer tube 28 into the die 33. The relatively higher pressure may be brought about by increasing the pressure in the vessel 3, or by a combination of pressure values applied to the pressure vessels and dies. One vessel 3 may supply one or more dies and a plurality of vessels 3 may be used to supply a plurality of dies that may require different casting time cycles, feeding techniques and casting pressures. Pressurizing medium for the vessel 3 may be compressed air or an inert gas, e.g. nitrogen, argon or carbon dioxide. The pressure may initially be such as to slowly feed the die without turbulence and then is increased, and a nozzle 29 at the end of the transfer tube 28 is designed to give optimum flow and cooling characteristics. The valve 20, 21, which may be water-cooled, is operated by a rod 22 by mechanical, pneumatic, hydraulic, electrical or gravity means. The die is formed in two parts that are closed together by jacks 34 and clamped by jacks 35 in sequence. A control sequence (Fig. 4, not shown) is described and includes pilot switches, timers &c. for controlling a casting operation including the insertion and removal of cores in the die. Ceramic coating or linings may be used in the apparatus and the vessel 3 may be made of ceramic with an integral transfer tube 28. The materials cast may be aluminium and magnesium based alloys.