Continuous high speed plastic bag fabricating machine
US3994209A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 1974 |
| Grant date | Nov 30, 1976 |
| Priority date | — |
| Expiry date | Dec 12, 1994 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB31B2160/10
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A method and apparatus for the continuous manufacture of plastic bags from an extruder which includes a differential tachometer which senses the speed of the film in two locations so that the film drive can be adjusted to compensate for the shrinkage of the film and to eliminate tension in the film. Welding and perforating blades are provided which contact the travelling film and travel with the film to complete their weld and perforations before returning to their initial positions. One type of welding and perforating device uses a pair of opposed blocks which come together around the film and travel with the film while the perforating blade pierces through the film and the weld is being completed. A timing cam coupled to the film drive determines the spacing of the welds and perforations and thus the length of each bag produced. A separating device is also included so that if the bags are perforated and include a cut line along their perforations, a pair of faster moving rollers can be engaged to the moving film to pull the perforations apart and separate the bags.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.