Patent GB-785837-A (GB)
Title: Method of and means for casting metals
IPC: B22D17/00
Filed: 1954-11-12
Abstract: 785,837. Casting-machines. HARRISON, G. Nov. 12, 1954 [Nov. 23, 1953], No. 32891/54. Class 83 (1). A casting-process comprises partly immersing the mould in a bath of molten metal to introduce the metal through an entry in the mould, applying suction to the mould to withdraw air from the cavity, and retaining the mould partly immersed to maintain it heated in the region of the entry and circulating a coolant around the walls of the mould element forming the mould cavity to effect cooling of the remainder of the mould to permit solidification of the cast metal progressively inwardly from the mould-walls while the mould remains so partly immersed, so that during solidification liquid metal flows into the mould as the metal therein shrinks on cooling. The machine 1 comprises a mouldassembly 10, 12, ejecting apparatus 14, and control and timing apparatus 16 &c., carried on a support 6 movable on wheels 30. The upper die-assembly 10 comprises a copper block 69 and a water-air-vacuum distributer-block 71, connected to the piston-rod 64 of an hydrauliccylinder 68 carried on a frame-base 40. The blocks 69, 71, Fig. 8, comprise cooling-water passages 86, 88, 88<SP>1</SP>, 92, 94, and vacuum may be applied to the mould-cavities 70 through holes 72 plugged by plugs 76 which leave a clearance too small for the flow of molten metal therethrough. The lower die-assembly 12 comprises a pan 130 of high melting-point alloy having gates 134 corresponding to the diecavities 70, and supported on guide-bars 142, one on each side of the cylinder 68 and supported by a frame-assembly 50, which is slidable in horizontal grooves in the frame-base 40. The frame-assembly 50 comprises upstanding slotted cam-plates 120 into which may engage rollers 116 carried by a rod 112 connected to the upper die-assembly so that the frame-assembly 50 may be moved horizontally thereby. Compression-springs 168 normally urge the bars 142 to a position where the bottom of the pan is above the top of the crucible 4 with which the machine is associated. The ejecting-mechanism 14 is carried between plates 60 depending from the frame 50 so that it moves as a unit with the pan 130, under the control of the cams 120. Slidable in guides 181 with respect to the plates 60 is a shoot support-member 206 carrying a shoot 209 for guiding completed castings, dropped thereon from the upper die-assembly 10, to a storage-bin. The front of the supportmember 206 is connected to an hydraulicallyactuated piston-rod 192, and supports a carrierplate 200 whose arms 202 locate the ejector with respect to the lower die-assembly when in the operative position, and an air-actuated device 240 comprising a piston 244 carrying an ejectorplate 248, 250 whose pins eject the solidified slugs from the gates 134. The operations of the machine are controlled by the timing and control-apparatus 16, which includes an electricmotor 261 driving a vacuum-pump 270 and, through a speed-reducer, a cam-shaft whose cams 280, 282, 284 actuate an hydraulic controlvalve 97 controlling the movement of the upper die-assembly, an air-pressure-valve 260 which controls the operation of the slug ejector 240, and vacuum valve 215 which controls the timing of the application of suction to die-cavities 70 to maintain the finished castings in the cavities when the upper die-assembly separates from the pan 130. The casting sequence is initiated after the pan has been raised to red heat by immersion in the melt by actuation of valve 97, the upper die-assembly thereupon moving downwards. A valve 100, Fig. 1, is thereby actuated to cause air to flow to the ejection-cylinder 190 to move the ejecting-apparatus away from the pan. The die-block 69 engages the pan 130 and depresses it into the melt and the mould cavities begin to fill without turbulence, an adjustable bleedervalve in the control-circuit having been previously adjusted to provide the necessary vacuum for such a flow. After the cavities have been filled and the castings solidified, vacuum-control-valve 215 is opened by the cam-shaft to apply vacuum to the die-cavities independently of the bleeder-valve. The valve 97 is actuated to raise the upper die-assembly 10, the pan 130 following under the action of the springs 168. Before the die-members are separated by engagement of collars 162 on the guide-rods 142 with stops on the frameassembly 50, the lower die-assembly is moved forwardly by the rollers 116 in the cam-plates 120 so as to shear the castings from the runners. The valve 100 is actuated by the control-arm 98 to move the ejecting-mechanism into operative position between the die-block 69 and the pan 130, and valves 216, 214 are actuated to remove vacuum from the cavities 70, and airpressure is applied to eject the casting on to the shoot 209. In a modification, Fig. 10 (not shown), the upper die-assembly comprises airoperated ejecting-pins. The castings are held in the cavities by a slight lip around each cavityopening, and the castings are subsequently ejected by operation of the pins.