Cutting device

Abstract

For cutting polymer films, e.g. a continuously moving web of polymer film, there is accomplished relative movement between the film and a cutting edge which is a substantially continuous and generally razor-sharp edge located at the periphery of an indexing steel sheet disc having a generally circular shape and a thickness in the same order of magnitude as the thickness of the polymer film; after maintaining the disc in a first angular position where an incremental portion e.g. 1 to 10 degree of a 360.degree. periphery, of the cutting edge is in film-cutting position for a period of cutting time, the disc is indexed and a subsequent incremental portion of the edge is moved into film-cutting position and held there for another period of cutting time. This is repeated until a major part and preferably all of the continuous edge has been indexed. Then, the disc is exchanged. When using an automated indexing actuator, e.g. a step-motor, and monitoring cutting time, the frequency of step-switching can be adapted to the periods of time during which the incremental edge portions of the indexing blade are in cutting position. Near completion of an indexing cycle, a signal is generated and a fresh blade is put into operation. As a consequence, a perfectly sharp edge portion of the indexing blade will be in film-cutting position at any time, thus providing for reliable cutting of the film, e.g. emerging as a tubular film from extrusion, even when highly abrasive films are processed.

Dependencies are inferred from the claim text.