Patent ID: 7082979

Claim:
A heat sealing wheel assembly for a shrink wrap machine, the assembly providing side cutting and heat sealing of thermoplastic film, and wherein waste film is produced during the side cutting and sealing, the assembly comprising: a gripping mechanism for gripping side edge portions of overlapped plies of thermoplastic film and for feeding the overlapped plies in a direction for heat sealing by at least one heat sealing wheel, at least one such heat sealing wheel; a gripping mechanism for gripping side edge portions of overlapped plies of the thermoplastic film and for guiding and feeding the overlapped plies in a direction for heat sealing and cutting by the heat sealing wheel; a heating hub of the heat sealing wheel for heating the heat sealing wheel sufficiently to effect a continuous side seal of overlapping plies of the thermoplastic film and to cut off a waste portion of the plies, the heating hub having an outer circumferential edge; relative diameters of the heat sealing wheel and heating hub of the heat sealing wheel assembly being configured such that the heating hub has a diameter relatively less than a diameter of the heat sealing wheel so as to create an annular region near an outer circumference of the heat sealing wheel, and such that said annular region defines a free space extending beyond the outer circumferential edge of the heating hub and constituting an access gap for access by said gripping mechanism to an exposed edge of the side edge portions of overlapped plies of the thermoplastic film to permit close engagement of the gripping mechanism for grasping and guiding the side edge portions of thermoplastic film next to a point of contact of the heat sealing wheel with the plies of film; the annular region avoiding obstruction by the heating hub as overlapped plies of thermoplastic film are guided and fed by the gripping mechanism for heat sealing and cutting by the heat sealing wheel such that close gripping engagement of the plies is provided by the gripping mechanism to reduce an amount of waste film that must extend out from a point of sealing contact with the heat sealing wheel.