Method and apparatus for registration of a seal and perforation on a plastic bag

摘要

A method and apparatus for registration of a seal and perforation on a plastic bag include a drum for forming a seal on a continuous plastic film with respect to a registration mark on the film and a perforator/cutting station for forming a perforation on the film with respect to the location of the seal. This method and apparatus is used in a plastic bag making machine to produce bags of different lengths. A detector locates the registration mark printed on the film and the drum diameter may be adjusted to form the seal at a desired location on the film with respect to the registration mark. A seal detecting station locates the seal and a controller adjusts the speed of the perforator/cutting station to properly locate the perforation with respect to the seal and to maintain a desired skirt length.