Method and apparatus for vacuum/pressure thermoforming
US5641524A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Jun 24, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C2791/007
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An apparatus for plug-assisted thermoforming of a cup or other hollow article has a concave well or cone region machined into its top with a series of small holes drilled near the deepest part of the well and connected to a port inside the plug which is connected to a specifically sized manifold system. The manifold has a source for positive (pneumatic) and negative (vacuum) pressure air. During the machine cycle, a vacuum is introduced into the plug, which draws the hot plastic sheet into the plug well to stretch it. The vacuum is replaced by compressed air to transfer the pre-stretched sheet into a mold. In a particularly preferred embodiment, the plug is shaped to provide stretching in both the central well and in peripheral regions concentric with the well. Controlled air pressure in the mold may be used to provide the concentric prestretching.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.