| 摘要 |
Combustible patterns of expanded polystyrene, carved to complex forms by the tape-controlled milling of two or more self-aligning parts, resist displacement from each other as sand is packed within and around them. Tongue-and-groove joints, formed on the mating surfaces of the parts, locate and align the parts and prevent their displacement more surely than adhesives, which tend to cause inclusions and voids in the casting. Adhesive may be coated on the tongue-and-groove parts only, leaving adjacent margins of the mating surfaces free from adhesive; and the exterior surfaces of the assembled pattern may be coated with a noncombustible ceramic coating. The marginal spacing of the adhesive inward from such coating permits quick dispersion of the adhesive when the molten metal is cast.
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