초록 ▼

Apparatus for producing a machine-direction intermittent heat seal in a moving web of plastic film including a block adapted to be supported on one side of the hem and having a plurality of wheels having heat conducting surfaces spaced around the periphery and mounted on the block at spaced location

Apparatus for producing a machine-direction intermittent heat seal in a moving web of plastic film including a block adapted to be supported on one side of the hem and having a plurality of wheels having heat conducting surfaces spaced around the periphery and mounted on the block at spaced locations in tandem for engaging the film along the path of the intermittent heat seal to be formed in the hem. The block has a corresponding plurality of surfaces each of which is adapted to be engaged by a side of one of the wheels. Gears interconnect the wheels to maintain the wheels in register with the intermittent portions of the heat seal in the hem during rotation of the wheels. A heater is provided for heating the block and its plurality of surfaces and springs are provided for maintaining the wheels in contact with the plurality of surfaces whereby movement of the hem through the heat sealing apparatus causes the plurality of wheels to rotate and maintain contact with the plurality of surfaces whereby the wheels are in turn heated by conduction from the block and produce the intermittent heat seal in the hem.

대표청구항 ▼

Apparatus for producing a machine-direction intermittent 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 wheels having heat conducting surfaces spaced around the periphery and mount

Apparatus for producing a machine-direction intermittent 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 wheels having heat conducting surfaces spaced around the periphery and mounted on said block at spaced locations in tandem in the direction of web movement for engaging one of the opposing layers of film at intermittent locations 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 wheels, gear means interconnecting said wheels to maintain said wheels in register with the intermittent portions of the heat seal in the hem during rotation of said wheels, means for heating said block and its plurality of surfaces, means for maintaining said wheels in contact with said plurality of surfaces on said block for heating said wheels by conduction from said block, and means supported on the opposite side of the web comprising a plurality of back-up rollers for engaging the opposing layer of film in the hem and cooperating with said plurality of heated wheels to press together the opposing layers of film in the hem, said plurality of heated wheels and said plurality of back-up rollers being freely rotatable whereby movement of the web through the heat sealing apparatus causes said plurality of heated wheels and said plurality of back-up rollers to rotate and heat seal the opposing layers of film in the hem at the intermittent locations along the path of the hem in the direction of web movement to produce the intermittent heat seal in the hem.