Stock material or miscellaneous articles – Perimeter or corner structure of sheet
Patent
1981-05-18
1983-02-01
Thibodeau, Paul J.
Stock material or miscellaneous articles
Perimeter or corner structure of sheet
264230, 264342RE, 264544, 428174, 428220, 428910, B29C 1704, B29C 2500
Patent
active
043715753
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to rigid shaped bodies, suitable as light structural elements and preferably translucent. Shaped parts of this type are, for example, transparent domes or barrel vaults made of acrylic glass sheets. They are primarily used as roof elements. The aforementioned shaped bodies do not represent the best technical solution for all loads encountered in practice. Thus, in an uneven stressing of a transparent dome from above, all the forces involved are converted into pressure or buckling strains. The resistance to buckling may then be exceeded locally and the dome caved-in. This process may result in a break in the dome. Simple barrel vaults are even more sensitive in this respect.
DESCRIPTION OF THE PRIOR ART
Transparent domes are extremely rigid structures, which is desirable in many cases but is often also disadvantageous. For covering cable networks, grid shell constructions, and similar substructures which are not completely rigid, form-retaining essentially rigid shaped bodies are desired in the construction of larger closed coverings; the shaped bodies should, however, be capable of limited movement without break if the substructure is elastically deformed. Barrel vaults in accordance with DE-OS No. 21 07 728 are essentially more flexible but cannot often be used because of the scanty resistance to buckling mentioned above.
A disadvantage common to transparent domes and barrel vaults is that, in an array of these structural elements to form longer strips or larger areas, the synthetic resin surfaces always are the parts of the roofing that project highest. With roofings of this type, then, no scaffolding, cables, or the like can be laid on them during repair or maintenance work without endangering the plastic material.
A rigid, one-piece shaped synthetic resin body which can be used as a roof covering element, the edge of which body does not lie in one plane, is known from DE-AS No. 24 30 182. Because it includes a frame which is of one piece therewith, the known body is completely torsion-resistant and is not capable of elastic deformation. Its surface is significantly larger than the imagined planar surface enclosed by the edge. The shaped body has the same disadvantages, described above, as other known roofing elements, for example, transparent domes.
SUMMARY OF THE INVENTION
The object of the present invention is to avoid these disadvantages with the type of shaped body specified in claim 1. It has been found that this object was achieved by shaped bodies of a kind that have a surface smaller than the imaginary smooth initial surface enclosed by the edge of the shaped body.
The imaginary flat initial surface is a surface which is generated from a planar surface by warping or bending around one or more fold lines. The edge of the shaped body of the invention always lies in such a flat initial surface. The surface is geometrically indicated as flat because its generatrix is a straight line. Examples of this type of flat initial surface are cylindrical and conical or saddle-roof surfaces. The edge of the shaped body to be sure lies in a flat initial surface of this type, but not in a plane in the narrow sense, that is, not in a plane in which any number of straight lines can be run through every point thereof.
The flat initial surface enclosed by the edge of the shaped body is not simultaneously the surface of the shaped body of the invention. The surface of the latter differs from the flat initial surface and is smaller. Exceptions aside, the surface of the shaped body of the invention does not belong geometrically to the class of flat surfaces, since its generatrices are not straight lines. The surface is an anticlastic, i.e. saddle-shaped, warped surface with negative Gaussian distortion and is not capable of being spread out into a plane. In the ideal case, it is a minimum surface, that is the mathematically smallest possible surface enclosed by the given edge. For reasons which need not be discussed here, the preferred shaped bodies of the invention
REFERENCES:
patent: 3000057 (1961-09-01), Swedlow et al.
patent: 3727356 (1973-04-01), Appenzeller
patent: 3894137 (1975-07-01), Moench
patent: 4160799 (1979-07-01), Locey et al.
Kerk Klaus
Mueller Dieter
Oleiko Bernd
Rohm GmbH
Thibodeau Paul J.
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