a set of elements of foundry equipment used for forming the outer contours and inner cavities of castings in a mold.
A gated pattern consists of casting patterns, pattern and stripping plates, core boxes, patterns of parts of the gating, molding and control patterns, jigs, and drying plates. Specialized flasks are also included in gated patterns. Certain elements may be eliminated, depending on the technology of production of the mold.
Wood, plastic, metal, or plaster are used as materials for gated patterns. The choice of a material is determined by the nature of the production process, the process of production of molds, and the requirements for precision and surface quality of the casting. More than 60 percent of castings in the USSR are produced using wood gated patterns. There is a tendency toward increased production of castings using metal and plastic gated patterns. For castings from all alloys, linear shrinkage of the alloy is taken into account in preparing the gated pattern.
Three classes of wood gated patterns are distinguished according to strength. The strength class determines the structure and quality of preparation of the gated pattern, which, in turn, determine its durability and the precision of its dimensions. Wood gated patterns are divided into three classes of precision, depending on the required class of precision of the casting; the precision of a gated pattern should exceed the required precision of the casting. Where necessary, rapidly wearing sections of the wood patterns are reinforced with metal. The durability of metal gated patterns is improved mainly by chrome-plating the parts. Standardized elements are used in making wood gated patterns.
The main piece of equipment in pattern shops or sections is the woodworking machine. Metal gated patterns are produced in metal-pattern sections of tool shops or in metal-pattern shops. Large-scale pattern-producing shops serve a number of foundries. Special metal equipment (usually made of gray cast iron), which can withstand heating to 400°C, is used for preparing molds and cores made from thermosetting materials (shell molds and cores; three-dimensional cores, which harden in “hot boxes”).
Gated patterns are stored in specially equipped pattern storage rooms at about 20°C and relative atmospheric humidity of 60 percent.
REFERENCESPoliakov, D. S., and V. L. Tarskii. Liteinye model’nye komplekty. Moscow, 1967.
Klebaner, V. Ia. Ekonomika i organizatsiia model’nogo proizvodstva. Leningrad, 1968.
Lozhichevskii, A. S. Izgotovlenie liteinykh metallicheskikh modelei. Moscow, 1969.
Balabin, V. V. Model’noe proizvodstvo. Moscow, 1970.
Balabin, V. V. Izgotovlenie dereviannykh model’nykh komplektov v liteinom proizvodstve, 2nd ed. Moscow, 1971.
V. L. TARSKII