Blind riser for foundry moulds - with outer sheath made of foamed polymer, which burns during casting and thus provides thermal insulation surrounding metal in riser

摘要

This is an addn. to 2928166, which described a hollow blind riser made of refractory material, esp. resin-bonded shell moulding sand. The riser is inserted in a mould, and contains one or more cores permeable to gases; it also has a double wall, and an outer sheath of foamed polymer. The novelty in the present invention is that the riser has an inner wall joined by a ring base to an outer wall, thus forming a monolithic structure. The patent is pref. also an addn. to 2907301; and has a ring recess in the top surface of the foamed polymer sheath. The recess is used for the simple vertical stacking of the risers. Simplified mfr. of the risers, where the foamed polymer sheath provides protection during packing and shipment of the risers, while also providing thermal insulation for the metal in the riser during casting.