Abstract: A municipal casting frame is provided with cast nut retainers that allow the frame to be used with or without a bolt-down cover. The frame defines one or more bolt holes of sufficient dimension to allow free passage of the cover bolts. The undersurface of the frame defines a cast nut retainer adapted to securely receive a nut. In one embodiment, the nut retainer includes protrusions that permit the nut to be snap-fitted into the nut retainer. In another embodiment, the nut retainer is configured to frictionally receive the nut in a wedging interaction. The present invention also provides a method for manufacturing a frame with integral cast nut retainers. The method generally includes the steps of (a) providing a core corresponding in shape to the bolt hole and the cast nut retainer, the cast nut retainer being configured to receive and retain a nut, (b) casting a frame in a mold about the core, (c) removing the cast frame from the mold and (d) removing the core from the cast frame.

Abstract: A method for forming casting molds, comprising forming a flexible pattern composed of rigid plates and a flexible cloth, the rigid plates being adhered to the flexible cloth with intervals between plates, and the flexible pattern being made an air-tight construction, pouring a fluid into the flexible pattern or supplying the fluid under pressure to form any desired shape thereof, discharging the fluid from the flexible pattern after a sand mold has been cured, and then withdrawing the flexible pattern from the sand mold.

Abstract: In a system for the production of molds for casting, a pair of pattern plates are disposed in an opposed facing relationship with a frame located therebetween in a manner whereby the opposing pattern surfaces of the plates, together with the frame, define an enclosed cavity within which a casting mold section may be formed. The frame is preferably provided with an opening through which the cavity may be filled with molding material which, after hardening, forms a mold section. After separation of the pattern plates and frame, the mold section is conveyed into assembled relationship with one or more other mold sections in order to form a mold for casting. Pattern plates and frames may be arranged in a mass production facility to continuously form mold sections which, when assembled, will provide a mold stack for producing multiple castings.