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US 7,824,597 B2Granted
Method and apparatus for making flat molded plastic articles
AssigneeKraussMaffei Technologies GmbH
InventorBernd Klotz
Life of this patent
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Abstract
In a method for producing flat molded plastic parts, for example panes, a mold is first filled completely with plastic material and additional plastic material is subsequently added, in such a way that the mold distends in a defined manner in opposition to the clamping force. The distension compensates for material shrinkage during a subsequent cooling operation, thus preventing sink marks and permitting the production of, for example, panes of high optical quality.
Claims8
A method of making a molded plastic article, comprising the steps of:
- closing a cavity of a positive mold by applying a clamping force;
- fully filling the cavity with plastic material, while maintaining a size of the cavity constant;
- adding plastic material so as to distend the positive mold in opposition to the clamping force until the cavity of the positive mold expands to reach a defined size for producing a defined article thickness;
- closing the positive mold until reaching a residual distending opening and molding the plastic material into a plastic article while applying the clamping force to thereby maintain the plastic material compressed;
- and
- removing the plastic article.
3 more elements
Dependencies are inferred from the claim text.