1. Field of the Invention
The present invention is broadly concerned with an improved casting method and apparatus particularly adapted for low-cost, high-output production of unitary, monolithically formed structures such as pet houses, storm shelters, box culverts and modular rooms. More particularly, it is concerned with a casting or forming system making use of inner and outer, telescopically interfitted form members provided with selectively operable jacking structures for quickly and easily separating the forms from a completed, cast structure without the need for disassembly of either form member.
2. Description Of The Prior Art
A large number of reusable, metallic concrete forms have been used in the past in the fabrication of walls, tubes or other structural components. Generally speaking, such forms are provided with connection hardware such as crosspieces and pin assemblies for coupling of form sections on site. Such procedures are time-consuming and necessitate disassembly of the entire form after each use thereof.
It has also been known in the past to factory form relatively small concrete enclosures such as storm shelters with reusable forms. Here again, these prior forms are characterized by a plurality of interconnected panels which must be at least partially disassembled after each enclosure is cast. Furthermore, the seams between form panels tend to leak concrete, which necessitates additional time in cleaning of the forms after use. A related problem with typical concrete forms in this context is that they can be used only for the production of a tubular, box-like structure which must then be capped with a separate ceiling section to form a complete enclosure. A patent to Haas, U.S. Pat. No. 3,297,295, discloses an apparatus for removing forms from large concrete tanks having a bottom. The '295 patent teaches a forming system having an inner mold, an outer mold having an open top, and jacking beams extending across the top. These beams support a jacking mechanism that also presses against a solid concrete body within the form. In this manner, the outer form may be separated from the solid body by operating the jack to exert a lifting force. Nevertheless, the beams are positioned in an awkward position (across the middle of the open top of the outer form) that interferes with concrete pouring operations as the assembled form is filled with concrete. Furthermore, top jacking from a crossbeam can cause uneven jacking forces that, due to small uneven form movements during jacking operations, may bind the outer form with the formed concrete body as the outer form is removed.
There is accordingly a need in the art for an improved casting method and apparatus which eliminates form disassembly while also permitting casting of complete, monolithic enclosures in a single step while providing easy separation of the casting form members from the enclosures.