Process for manufacturing tough plastic articles of manufacture
Abstract
Abstract A METHOD FOR FORMING PLASTIC ARTICLES HAVING IMPROVED STRUCTURAL PROPERTIES. A PORTION OF A THERMOPLASTIC SHEET IS CLAMPED ABOUT ITS PERIPHERY AND THE CLAMPED PORTION BROUGHT TO A TEMPERATURE AT WHICH IT CAN BE ORIENTED. THE SHEET PORTION IS THEN DRAWN AXIALLY INTO A MOLD CAVITY AND RADIALLY OUTWARDLY AGAINST THE SURFACE OF THE CAVITY SO AS TO STRETCH AND ORIENT THE SHEET. THE DRAWN MATERIAL IS THEN SEVERED BELOW AT LEAST ONE-HALF THE TOTAL DRAW BETWEEN AN EDGE PERIPHERALLY SURROUNDING THE DRAWN MATERIAL AND THE SIDE OF A PLUNGER ADVANCING IN THE DIRECTION OF THE AXIAL DRAW SO AS TO FORM AN ORIENTED ARTICLE FROM THE PORTION OF THE DRAWN MATERIAL BELOW THE EDGE. THE AXIAL DRAW MAY BE CARRIED OUT USING THE SAME PLUNGER USED TO SEVER THE MATERIAL. A DIFFERENTIAL PRESSURE MAY ALSO BE USED TO EFFECT THE RADIAL DRAW.
Inventors
- 👤 George E Walker
Bibliographic Details
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