| 摘要 |
In a method of forming foundry sand moulds employing a cold-setting sand mixture pressed around a pattern by the use of pneumatic pressure acting on a flexible diaphragm, the sand is formed into a horizontal layer of approximately uniform thickness in a frame of which the bottom wall is formed by the diaphragm, the pattern is then pressed into that layer of sand, causing the diaphragm to bulge downwards, then the gas pressure (conveniently air pressure) is applied to compact the sand, which thereupon sets to allow separation of the resultant mould body from the diaphragm and pattern. During the initial formation of the layer the diaphragm can be supported by a further, stronger diaphragm, which is perforated to allow the gas pressure through, or by a rigid pad, or both.
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