Method and apparatus for differentially heating and thermoformin

Details Method and apparatus for differentially heating and thermoformin Method and apparatus for differentially heating and thermoformin

1992-07-07

1994-03-01

Timm, Catherine

Plastic and nonmetallic article shaping or treating: processes

Carbonizing to form article

Agglomeration or accretion

264522, 219773, 4251748E, 425160, 425DIG13, B29C 3514, B29C 5142

Patent

active

052904903

ABSTRACT:
A method and apparatus for thermoforming 3-dimensional articles of chosen wall thickness dimensions from a polar polymer sheet. The polymer sheet is dielectrically heated, the heating being controlled to impress a predetermined thermal pattern on the sheet. The thermal pattern is selected in accordance with the amount of stretching to which each area of the sheet is subjected during the subsequent work-forming step, the areas subjected to greater stretching being heated to a lower temperature and vice versa. Thus, the stretching action is balanced and results in accurate control of the wall thickness of the final article.

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