| 摘要 |
PROBLEM TO BE SOLVED: To provide a vacuum shutoff valve that needs no vacuum shutoff by molten metal at its upstream stop valve section, is simple to inspect and maintain owing to less abrasion of the stop valve, and dispenses with heating energy for maintaining molten metal in a constant phase. SOLUTION: The vacuum shutoff valve is provided with a casing 6 connected to the lower end of a down passage 1 for molten metal with a stop valve 3 at its upper end, a valve seat plate 12 formed with an opening 13 of a diameter larger than that of the passage 1 and mounted in the upper section of the casing 6, a valve element 20 having a valve plate 24 housed for traverse motion in a valve chest 11 under the valve seat plate 12 and brought into pressure contact, when advanced, with the lower surface of the valve seat plate 12, an O-ring or seal ring 27 mounted on either of the valve seat plate 12 and the valve plate 24 to seal the opening 13 when pressed thereagainst, and a drive 28 for reciprocating the valve element 20 so as to bring it, when retracted, in a standby position with no interference with the molten metal flow.
|
