Method and apparatus for differentially heating and thermoforming a polymer sheet
US5290490A · kind A · utility
29Cited by
17References
21Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 7, 1992 |
| Grant date | Mar 1, 1994 |
| Priority date | — |
| Expiry date | Jul 7, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S425/013
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.