GB991513A - Improvements in and relating to composite articles - Google Patents

Abstract

991,513. Casting machines; casting composite articles. E. A. THOMPSON. March 26, 1963 [April 2, 1962], No. 11834/63. Heading B3F. A method of making a composite casting comprises introducing a first amount of molten metal into a mould and allowing it to cool until a surface skin has formed thereon and then introducing a second molten metal into the mould into contact with the said skin to remelt it and cause the metals to mutually blend within a junction zone. In a machine for casting valve tappets in shell moulds, the first and second molten metals are supplied from a pair of spaced, heated containers 16, 16<SP>1</SP>, the moulds 10 being positioned successively to receive metal from each source by an. intermittently moving rotating table 14, or endless chain &c., driven by a fluid motor 138 through a step-bystep mechanism. Each container is pressurized by an inert gas from a source A and the level of molten metal therein is maintained between limits, the container being pivotally mounted on a bracket 34 movement of which due to variations in weight of the melt actuates limit switches LS1, LS2 controlling a solenoid which actuates a valve rod 24 in a second container 22. The valve rod 24 is oscillated and in the pouring position shown in Fig. 1 molten metal is delivered to the container 16, 16<SP>1</SP> by pressurized inert gas supplied through the valve rod 24 from a valve 122. Each pouring container 16, 16<SP>1</SP> comprises a valve 18 for metering a predetermined quantity of molten metal to the mould, the hollow valve rod 18 being oscillated about its longitudinal axis by a fluid motor 62. In the pouring position shown in Fig. 1, metal from the container 16 cannot enter the measuring cavity 46 in the valve rod. When the rod is oscillated a port 44 disconnects from the pouring spout 32 and connects with an inlet port 42 while simultaneously a predetermined volume of inert gas is admitted to the interior of the rod by a valve 132 to regulate the volume of metal entering the cavity 46 from the container 16. Oscillation of the valve 18 then connects the port 44 with the pouring spout 36 and the pressure of the now heated gas in the valve rod 18 forces the measured charge into the mould, followed by some escaping gas to minimize oxidation of the metal in the mould. The second metal is similarly metered and poured from the second source 16<SP>1</SP>. The moulds are fed to and removed from the table 14 by pivoting arms 174, Figs. 4 and 5, which comprise fluid-piston actuated jaws 195. The various fluid motors and valves &c. are operated in timed sequence by a cam-shaft 210, Fig. 1.