Permanent moulds, made esp. of steel, for mass prodn. of castings - where two pattern halves of castings required can be used for mfg. permanent moulds

摘要

The actual casing required is reproduced as two halves of a pattern. Each pattern half is located on a pattern plate and covered with a polymer foil and then a moulding frame. The frame is filled with binder-free sand and then closed by a second polymer foil. A vacuum is used to compact the sand round the pattern. The pattern half is next removed so a second, positive mould can be made, also using polymer foils and binder-free sand. The two positive moulds thus obtd. are used in conjunction with two more moulds to make two pairs of moulds, each consisting of a cope and drag. Each pair is used to cast one half of a permanent mould, pref. by using molten steel to fill the moulds. Two pattern halves can be used for the casting of two steel permanent mould halves. The two permanent mould halves are then assembled together for the mass prodn. of castings.