| 摘要 |
PURPOSE:To make the pressure to be exerted upon the molten metal surface for casting constant at all times and to assure normal casting in a bottom casting device under pressurization by operating electromagnetic stop valves mounted to a pressure supply line by the pressure difference between a pressurizing chamber and a mold chamber. CONSTITUTION:The surface of the molten metal 1 in a vessel 2 in a pressurizing chamber 3 is pressurized with a gas and molten metal 1 is lifted through a bottom opening 5 into the mold 6 installed in a mold chamber 8, whereby bottom casting is executed. In this case, the pressure difference between the chamber 3 and the chamber 8 is detected with a differential pressure detector 12, and the detected output thereof is amplified with an amplifier 13, after which the output is compared with the set value of a setter 15 for reference differential pressure, in a comparator 14. When the pressure difference between both chambers 3 and 8 is smaller than the set value on account of leakage of the device, etc., the molten metal 1 does not rise up to the mold 6, and therefore the compared signal is amplified with an amplifier 16, and is applied to electromagnetic actuating parts 22 for plural electromagnetic stop valves 21 provided in a pressure supply line 10 to open the valves of a required number among the valves 21, whereby the presure in the chamber 3 is increased and the molten metal 1 in the vessel 2 in the chamber 3 is lifted surely up to the mold 6. |
