GB1336305A - Methods of and apparatus for die casting metals - Google Patents

Abstract

1336305 Pressure casting machines GKN GROUP SERVICES Ltd 18 Nov 1970 [26 Nov 1969] 57750/69 Heading B3F A pressure die casting apparatus has a cavity 12 defined by dies 10 and 11 separable from one another at a parting surface 13, a chamber 20 connected to the cavity 12 by a passage 14 extending along the parting surface, a passage 21 extending along the parting surface for feeding molten metal into the chamber 20, means 19 for closing the passage 21, and means 18 for pressurizing metal contained within the chamber 20 to cause it to flow into the cavity 12. The closure means 19 may consist of a rotatable block having channels 21a and 25 therein. In one position of the block these channels form continuations of the feed passage 21 and a vent 30 respectively; in a second position the channel 21a is out of alignment with the passage 21 which is thereby closed, and the channel 25 is in alignment with the passage 14 and thus puts the chamber 20 in communication with the cavity 12. The chamber 20 may be formed as a shot duct 15 having a piston 18 which, in addition to forcing metal into the cavity, also ejects solidified metal from the duct 15 when the dies are opened. A stop may be provided for determining the initial position of the piston 18 so that the volume of the shot duct does not substantially exceed that necessary to accommodate the quantity of metal required to form the product proper, a sprue and a "biscuit". The initial position of the piston may be adjustable. Molten metal, e.g. cast iron or steel, is introduced into the shot duct through the passage 21, the block 19 rotated into its said second position, and the metal forced into the cavity 12 by the piston 18. The dies, block 19, shot duct and piston may be made of steel, alloys of Mo, W or Ta; ceramic or cermet materials. The shot duet and cavity 12 may be evacuated and more than one cavity may be provided.