Patent GB-621269-A (GB)
Title: Improvements in casting metal
IPC: B22D47/02
Filed: 1947-02-13
Abstract: 621,269. Casting machines and processes. NEW JERSEY ZINC CO. Feb. 13, 1947, No. 4198. Convention date, June 25, 1946. [Class 83 (i)] Moulds.-Apparatus for casting metal comprises a mould-carrying wheel mounted on a horizontal axis, driving means therefor for moving the moulds continuously and at a uniform speed through a casting zone and then through a cooling zone, a pouring ladle and means for automatically controlling the pouring so that each mould is filled to a predetermined level. The invention is described in connection with apparatus for casting zinc. Molten metal maintained at a substantially constant level in a melting furnace 25 is conveyed by a dipping ladle 2G to a pouring ladle 22 and thence to moulds 21 supported horizontally between plates 32 and 33 of a wheel 20 by which the filled moulds are carried through a cooling zone to a discharge station and round again to the casting zone. The wheel is mounted on a relatively heavy shaft 31 in relatively heavy bearings 34 and is driven from a motor through a belt 28 and reduction gear 30. A friction brake 144 may be provided to take up back-lash and produce smoother running. A number of horizontal shafts 35 extend between the sides of the wheel 20 and each carries a frame 36 supporting a mould 21, and exteriorly of the wheel, two arms 38, 40 having at their ends rollers 41, 42 which cooperate with guide tracks 44-47. In Fig. 5, a mould is shown in the casting zone at the upper part of the wheel. As the wheel rotates, the roller 41 bears on the inner side of the track 43 and so keeps the mould horizontal as it moves down through a cooling zone, where it is acted on by air jets and if desired, by liquid jets. As the mould reaches a position where the track would allow it to tilt, the other roller 42 comes into contact with an intermediate track 45, after which the roller 41 engages the outer face of a track 44. At the lower part of its path, the bottom part of the mould dips into water in a tank 117 to increase the rate of cooling. Extracting castings.-As the mould travels up on the other side of the wheel the roller 42 is engaged temporarily by a track portion 47 and the roller 41 first engages a stop 48 and then enters a tiltable track portion 46 by which the mould is inverted to discharge the casting on to a roller conveyer 121. Pouring-apparatus.-The pouring ladle is mounted on trunnions 62 on a carriage 65, Fig. 9, which is reciprocated along a track 66 by an arm 68 connected to a crank 71 on a shaft 54 driven from the reduction gear 30, so that during pouring the ladle moves with the mould. A fork 76 depending from the bottom of the ladle engages a crank 75 operated through a lever 73 from a hydraulic plunger 72 by which the ladle is tilted into pouring position. During the movement of the wheel, the dipping ladle 26 is rocked about its trunnions by means of a counterweighted arm 86, Fig. 11, which is rocked by an arm 95 coupled at its lower end to the crank 93 of a shaft 94, a roller 92 projecting from the coupling into a grooved crank arm 88 on a shaft 90 driven from the shaft 54, Fig. 13. When it is desired to pour metal from the dipping ladle into the pouring ladle, another hydraulic plunger 85 is actuated to lower the trunnions of the dipping ladle. The roller conveyor 121 is also actuated by levers from the shaft 54 so that it will move into position between two moulds when the upper one is to be inverted to discharge its casting. Thus the rotation of the wheel, reciprocation of the pouring ladle, rocking of the dipping ladle and movement of the conveyer are all synchronized. In addition, the shaft 94, Fig. 13, which is coupled to the shaft 54, has cams 96, 97 adapted to operate switches 98, 100 which control the actuation of the plungers 72 and 85 to begin the pouring of metal from the dipping ladle to the pouring ladle and from the latter to the mould. The cessation of pouring is controlled by another circuit under the influence of a bridge in one arm of which is a capacity formed by the surface of the molten metal in the mould and a disc 101, the supports 104 and 105 of which are coupled to the plunger 72 so that it is lowered to a predetermined position when pouring begins. Each mould is thus filled to the same height. The formation of scum may be prevented by continuously supplying sal ammoniac to the metal in the ladle or by providing an atmosphere of sulphur dioxide in contact with the surface of the metal. If desired, the dipping ladle could be replaced by a siphon.