| 摘要 |
1,174,699. Vacuum impregnating. WESTINGHOUSE ELECTRIC CORP. 26 Aug., 1968 [17 Oct., 1967], No. 40602/68. Heading B5A. A process for encapsulating electrical apparatus in a castable resin under vacuum conditions comprises maintaining a vacuum in the second zone of a vacuum chamber having three zones, loading a mould containing the apparatus to be encapsulted into the first zone, providing a vacuum in the first zone and transferring the mould to the second zone, returning the first zone to atmospheric pressure, filling the mould with castable resin, providing a vacuum in the third zone, transferring the mould to the third zone, returning the third zone to atmospheric pressure and unloading the mould. As shown, the vacuum chamber 12 is divided into three zones 36, 38 and 40 by gate valves 32 and 34. A conveyer system 41 comprising five independently driven sections 64, 66, 68, 70, 72 leads through the chamber 12 and the first zone 36 and the third zone 38 can be closed to the atmosphere by doors 20 and 22 pivoted about hinges 24 by cylinders 26 and carrying sections 44, 46 of the conveyer. The centre section 68 of the conveyer can be raised on a piston 80 to bring the mould 56 into contact with the resin supply nozzle 76; this conveyer section incorporating means to raise the tops of moulds of different heights to the same level and to index multi-cavity moulds containing more than one component to suitable positions for filling. The vacuum in the second zone 40 is maintained by continuous pumping and the first and third zones are connected to the same source by valves, as these two sections are never evacuated at the same time. The second zone is arranged to hold several moulds so that the electric components can be held under vacuum for some time before and after impregnating to allow the removal of as much air as possible. A control sequence for the apparatus is described.
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