摘要 |
<p>Molten metal is sucked into a pump tube and then expelled by a compressed-gas pulse. Directly prior to the supplying of the expelling pulse of compressed gas to the pump tube 7, the suction supply is cut-off, whereby the withdrawn portion of metal is expelled into the molten metal body 5 under the action of gravity and the compressed-gas pulse. To ensure the accurate timing of the suction cut-off moment and the gas pulse supply, the cover 8 of the pump tube 7 has mounted therein rod valves cooperating with a floating sleeve having its float actuated by the molten metal. The tube is placed in communication with the ambient atmosphere upon the valves being raised by the sleeve. The cover 8 has also mounted therein at least one electric contact probe wired into a circuit controlling the supply of compressed gas pulses. The cutting-off of the suction is effected by the motion of an inner nozzle in an outer one, the nozzles being arranged at the intersection of the suction line and the compressed gas supply line. <IMAGE></p> |