Plastic and nonmetallic article shaping or treating: processes – Utilizing heat releasable stress to reshape solid workpiece
Patent
1983-05-31
1984-11-20
Lowe, James
Plastic and nonmetallic article shaping or treating: processes
Utilizing heat releasable stress to reshape solid workpiece
264291, 425383, B29C 1702
Patent
active
044838140
ABSTRACT:
A rigid, one-piece, thin-walled shaped body of stretched plastic whose edge is not in one plane and which has a surface approximating the mathematical minimal surface is disclosed which can be produced with increased dimensional accuracy. A plane plate made of a biaxially stretched plastic at least 1 mm thick is caused to assume a shape which is not in one plane, for example, the shape of a semicylindrical surface, and the edge of the plate is fixed or held in that position. On being heated to a temperature in the thermoelastic range, the surface partially shrinks back and results in a shape approximating the minimal surface, while backshrinkage of the edge is prevented by its being held in a fixed position. Opposite portions of the fixed edge, between which the plastic plate extends rectilinearly, before backshrinkage of the plastic plate sets in, are spaced farther apart after heating and then fixed anew prior to cooling. In this way dimensional inaccuracies due to stresses are compensated after the means holding the plate edge are released.
REFERENCES:
patent: 2577620 (1951-12-01), Mahler
patent: 2702406 (1955-02-01), Reed
patent: 3020596 (1962-02-01), Clapp et al.
patent: 3175027 (1965-03-01), Harrison
patent: 3894137 (1975-07-01), Moenck
patent: 4302417 (1981-11-01), Michelothi
patent: 4371575 (1983-02-01), Kerk et al.
Hellmann Walter
Krajec Otmar
Lowe James
Rohm GmbH
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