GB654817A - Methods of making moulding shapes from sand and other powdered, granular, pasty, or fluent material - Google Patents

Abstract

654,817. Moulding processes; mould and core materials; patterns. VITKOVICKE ZELEZARNY, NARODNI PODNIK, and PETRZELA, L. Dec. 10, 1948, Nos. 32012 and 32013. Convention dates, Dec. 12, 1947, and Feb. 5, 1948. [Class 83 (i)] A method of preparing moulds or cores, patterns or other casting equipment from sand, carborundum, glass powder or other powdered, granular, pasty or fluent material is characterized in that the basic material is mixed with an auxiliary material, e.g. a binder, which is hardened, after the basic material has the required shape imparted thereto, by the action of a further substance. The further substance, which may constitute or contain the hardening agent, may be in the form of a gas, vapour, or liquid, which is blown into the mould or core, or is used to wet the latter. In a modification, a substance containing silicon or silica in suitable chemical combination is added to sand and after the sand mass has been shaped it is penetrated by a gas, vapour, or liquid which causes silica to separate out from the added substance in the form of a gel, so that solidification of the shaped body takes place. The added substance or binder may be sodium silicate, ethyl silicate, or methyl silicate. The precipitant may be carbon dioxide, ammonia, hydrochloric acid, methyl alcohol, ethyl alcohol, or acetone. In another modification a material containing the hardening agent in a chemically-combined innocuous form is incorporated in the mixture of basic and auxiliary material, prior to or during the shaping thereof, in a solid form and is thereafter broken up into components by heat or other means, one at least of the components constituting the hardening agent. In a further modification the basic material is mixed with a material which causes separation of a gel from a material containing silica which is introduced into the shaped body in the form of a gas or vapour.