| 摘要 |
The invention concerns a further development of the contact heating technique in connection with thermoforming of plastic sheet, laminate or the like. Known contact heating techniques in such connection - despite otherwise advantageous qualities as regards temperature reproduction and energy savings - have been found to produce negative effects for the cycle time of the machine used for thermoforming for purposes of heating, in that one is forced to lift the heat-producing element from contact with the web as it is pulled forward. This means that the technical complexity of the machine also increases. The invention, which intends to eliminate these drawbacks, involves in its broadest meaning a method and an arrangement for thermoforming of plastic sheet, laminate or the like 10, where the method is characterised in that the sheet is fed in the gap between at least two flat, essentially parallel surfaces 11, 12, at least certain of these surfaces are imparted vibrational movement with motion component at least in one plane perpendicular to said surfaces, and at least one 12 of the surfaces is heated. Accordingly, the arrangement for implementing the invention in its broadest meaning is characterised by means for forming a gap between at least two flat, parallel surfaces 11, 12, between which the sheet is fed, means 13 for imparting to at least certain ones of said surfaces a vibrational movement with motion component at least in one plane perpendicular to said surfaces, and means for heating of at least one 12 of said surfaces. <IMAGE> |
