Patent GB-712605-A (GB)
Title: A method of, and means for, inductively pumping molten metals
IPC: H05B6/20
Filed: 1949-05-26
Abstract: 712,605. Dynamo - electric machines. BIRLEC, Ltd. May 26, 1949 [May 26, 1948], No. 14059/49. Class 35 [Also in Group XI] Converting electrical energy into motion of fluids by the action of magnetic fields.- An induction pump comprises a chamber of substantially triangular shape in vertical cross-section for holding molten metal, an inductor unit 32 of submerged resistor type attached to one inclined wall 7 and having a primary transformer threading an inclined secondary loop 16, 18 opening into the chamber, and a tubular pouring spout 20 located in the chamber with one end extending into the secondary melting loop 18 and with its outer lip projecting from a wall 2 of the chamber opposite to the wall' 7, so that metal is forced through the spout by the induced pressure. The pump may be tilted about a horizontal axis extending through the discharge end 30 of the pouring spout during pumping to maintain the metal in the pump at a constant level, or molten metal may be added from a large metal supply furnace to the chamber to keep the level constant through side walls thereof at the same rate as it is discharged into a mould. The spaced duct 16 of the secondary loop is connected to the chamber by three inclined ducts and the spout 20 is inserted in the central duct 18, which has a smaller angle of inclination than the other two inclined ducts. The pump is mounted in a framework 29 and is tilted automatically at a speed which maintains the level of the molten metal constant during pumping by a hydraulic cylinder 31 pivoted at one end to the frame and at the outer end to the pump. The portion 8 of the vertical end walls converge inwardly towards the wall 2 having a flat face 10 through which the spout passes. A tubular nozzle 22 is inserted in the inner end of the spout 20, leaving a space between the nozzle and the channel 18. The spout has an internal restriction 24 at its lower end. The chamber is partly closed by a cover 12 with a heating strip 14. The pump has two primary coils as in Specification 642,199, [Group XI], which are connected in series for low power, singly for medium and in parallel for high power by push-buttons. Successive equal quantities of metal are delivered by connecting the coils in parallel intermittently for equal time periods. Each coil may be alternately energized by a time switch for a few minutes to prevent freezing of the metal in the pump, or a thermostat may control the connection of the coils singly or in series. Specifications 632,947 and 712,672 also are referred to. The Specification as open to inspection under Sect. 91 comprises also keeping the metal level constant in the spout at low and medium powers by selection of voltages through tap switches to ensure delivery of exact amounts of metal during pumping. An electric pyrometer connected to a thermocouple indicates or maintains constant the temperature An ammeter and a wall meter are provided, and capacitors maintain the power factor at 90 per cent. Current is supplied to the primary coils through an autostransformer with seven taps to give equal increments of power to the pump and may be connected through links to correct small changes in supply voltage. The contactors may be mechanically and electrically interlocked to maintain the desired power. Yellow, green and red lamps indicate low, medium and high power. The inductors are cooled by an air pump which has lamp indicators extinguished on occurrence of an overload before the operation of fuses, which have a time lag. A counter indicates the number of ingots made. This subject-matter does not appear in the Specification as accepted.