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Abstract

A three-dimensional flow molding process and associated molding apparatus for making plastic parts or pieces utilizing a radio frequency heating field and means for applying constant pressure, along with an even temperature gradient, to the plastic part. In the process two metallic mold halves are joined clamping therebetween an imprinted diaphragm having the plastic on one side thereof between the diaphragm and one of the mold halves. In one version which may be preferred in constructing planar (two-dimensional) pieces or parts, pressure is applied directly by closing the mold halves and the diaphragm has a constant thickness therealong to provide even heating of the plastic that is being molded. In another version of the invention preferably for molding three-dimensional parts, a liquid conductor, such as mercury, or a sodium or graphite solution extends about the other side of the diaphragm in a space provided in one of the mold halves. In this version each of the mold halves is preferably provided with means for cooling. After the plastic, which may be in many different forms, is in place and the mold has been closed, the field may be applied for, for example, 5 seconds. The pressure on the mercury is maintained for the initial 5 second interval and for an additional like interval to produce a part of high quality having an excellent and consistent imprint from the diaphragm.

First Claim