| 摘要 |
This provides a way of producing a sand mould which does not require heavy mechanical presses or violent vibration to ensure sand properly fills tight patterns in a mould. Sand is put into a buffer zone 40 via a feed device 2,3. Below the buffer zone 40 is a flask 10 and pattern plate 14, and the space between the buffer zone 40, the flask 10 and the plate 14 defines a charging chamber through which the sand must fall to produce the mould. This space, and preferably the buffer zone as well, is evacuated. This eliminates air resistance to the falling sand and, as a result, the sand fills the mould properly. The sand is allowed to fall after the vacuum has been established. The reason for evacuating the buffer zone is to bleed the sand of air. It is preferred that the pressure in the charging chamber is reduced further than that in the buffer zone, since a difference in pressure will further accelerate the sand towards the pattern plate.
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