초록 ▼

Apparatus for sealing a hem in a moving web of plastic film having a structure including a folding surface having a web passing on one side of the surface and an edge of the web on the other side of the surface to produce a hem in the web prior to leaving the surface. Heat sealing apparatus is suppo

Apparatus for sealing a hem in a moving web of plastic film having a structure including a folding surface having a web passing on one side of the surface and an edge of the web on the other side of the surface to produce a hem in the web prior to leaving the surface. Heat sealing apparatus is supported adjacent the structure for heat sealing the hem while the web is moving and prior to the sealed hem leaving the surface. The surface is provided with an opening in alignment with the heat sealing apparatus and the heat sealing apparatus seals the hem through the opening. The heat sealing apparatus includes a plurality of heated rollers supported on one side of the structure, the rollers being adapted to extend through the opening in the surface and backup rollers are positioned on the opposite side of the structure and in alignment with the opening for cooperation with the heated rollers to engage the opposite sides of the hem for heat sealing the hem while the web is moving and prior to the sealed hem leaving the surface.

대표청구항 ▼

Apparatus for sealing a hem in a panel of a moving web of folded thermoplastic film comprising: structure including a two-sided surface having the moving web passing on one side of said surface and an edge of the web wrapped around said surface on the other side of said surface forming the hem in tw

Apparatus for sealing a hem in a panel of a moving web of folded thermoplastic film comprising: structure including a two-sided surface having the moving web passing on one side of said surface and an edge of the web wrapped around said surface on the other side of said surface forming the hem in two layers of the web in the direction of movement of the web prior to leaving said surface, said structure having an opening in said surface extending along the path of movement of the hem; means carried by said structure on said other side of said surface for engaging the layer of the hem wrapped around said other side for maintaining the moving web of film tightly around said surface and against the opposite sides thereof to avoid formation of wrinkles in the film during the heat sealing of the hem; means supported adjacent said opening in said surface for heat sealing together the two web layers in the hem in the direction of movement of the web while the web is moving and prior to the sealed hem leaving said surface, said heat sealing means comprising a plurality of heated rollers mounted in tandem in the direction of movement of the web and supported at said one side of said surface, said rollers being positioned to extend through said opening in said surface; and backup means positioned on said other side of said surface in alignment with said opening for cooperation with said heated rollers to engage the opposite side of the hem for heat sealing the hem while the web is moving and prior to the sealed hem leaving said surface.