GB774798A - Improvements in or relating to the manufacture of shell moulds for casting metal - Google Patents

Abstract

774,798. Moulding-processes. DIETERT CO., H. W. March 12, 1954 [March 30, 1953], No. 7356/54. Class 83 (1). Shell-moulds are made by forcing a mixture of sand and a binder to fill the space between two separable container-parts, of which one is a cold pattern supported in a cold mould-box and the other is a cold dry plate having a form generally conforming to that of the pattern and so positioned relative to said pattern as to provide a free space corresponding to the mouldsection to be formed. The moulding-mixture is blown from a container 16 into the space defined by a pattern 34, a mould-box 28, and a dryer-plate 12 mounted on a base-plate 10 and located thereon by pins 14. The box 28 is bolted to a blow-plate 18. Pins 42 in the plate 12 have machined surfaces which provide smooth locating surfaces on the exterior of the mould, or surfaces 44 of the plate may be machined. The shells are formed with flanges 54, 56. After blowing, the base-plate 10 is lowered and the shell on the dryer-plate 12 transferred to a baking oven. In a modification the dryerplate is permanently connected to the blowplate and the shell is supported on the pattern during baking, or alternatively the assembly of mould-box, pattern, dryer-plate and shell, is removed from the blower, and the shell baked, while held between the pattern and the dryerplate, e.g. in a coke, coal, oil, gas, infra-red radiation or H.F. oven. The mould-mix may be rammed or jolted. Clamping and guiding moulds.-The mouldhalves 50, 52 are supported in a structure comprising a frame 60, plate 62, a movable clamping-plate 72 and mould-flange engaging members 76. The smooth locating surfaces or the exterior of the mould are engaged by heads 66 of bolts 64. Alternatively if the exterior of the mould is accurately finished by the use of a machined dryer-plate, the mould is engaged by plates 70. Mould materials.-The binder may be a coreoil of a drying type, with or without water, mixed with cereal-and-water to provide additional green strength, or employed with an oxygen-releasing agent such as ammonium nitrate or potassium perchlorate. The oil may be a copolymer fast-drying mineral oil which is largely or completely pre-oxidized. In an example a vegetable-oil such as linseed oil includes 2-10 per cent by volume japan dryer. The oil is not more than 2 per cent by weight of the mix. Thermal-setting resins such as urea- or phenol-formaldehyde resins, usually ¢-1¢ per cent by weight, may be used instead of oil.