| 摘要 |
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. The process may also include the step of inserting a nut into the cast nut retainer in a direction that is in substantial coaxial alignment with the bolt hole.
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