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Apparatus for heat sealing a hem in a moving web of plastic film using a plurality of rollers or wheels mounted on a block at spaced locations for engaging the film along the path of a heat seal to be formed in the hem. The rollers are heated by contact of one of their sides against a heated block.

Apparatus for heat sealing a hem in a moving web of plastic film using a plurality of rollers or wheels mounted on a block at spaced locations for engaging the film along the path of a heat seal to be formed in the hem. The rollers are heated by contact of one of their sides against a heated block. The small force holding the rollers against the heated block is provided by a slight angular orientation of the roller relative to the direction of film travel.

대표청구항 ▼

Apparatus for producing a machine-direction heat seal in opposing layers of thermoplastic film in a hem in a moving web of thermoplastic film, comprising: a block supported on one side of the hem, a plurality of rollers mounted on said block at spaced locations in tandem in the direction of web move

Apparatus for producing a machine-direction heat seal in opposing layers of thermoplastic film in a hem in a moving web of thermoplastic film, comprising: a block supported on one side of the hem, a plurality of rollers mounted on said block at spaced locations in tandem in the direction of web movement for engaging one of the opposing layers of film of the hem along the path of the hem in the direction of web movement, said block having a corresponding plurality of surfaces each of which is engaged by a side of one of said rollers, each of said surface being slightly angled with respect to the path of the hem in the direction of web movement, means for heating said block and its plurality of surfaces, and a plurality of shafts corresponding with said plurality of rollers, said shafts projecting from said corresponding plurality of angled surfaces of said block and supporting said rollers for free rotation about their axes with said one side thereof engaging said angled surfaces to provide a corresponding angled orientation of the axes of said rollers relative to the direction of web movement, whereby movement of the web through the heat sealing apparatus causes said plurality of rollers to rotate and the angled orientation of the axes thereof produces a force holding said rollers in contact with said plurality of angled surfaces whereby said rollers are in turn heated by conduction from said heated block.