Mobil Oil Corporation

Pactiv Corporation

Gerald E Rawlings

Gregory A Haverfield

David A Bryniarski

Earle R Powell

A method and apparatus for sealing a drawtape to a hem of a thermoplastic film structure is disclosed. The thermoplastic film structure includes a panel, the hem, and the drawtape. The hem is formed along one end of the panel, and the drawtape is housed within the hem. In the method, the film structure is conveyed to a stationary heat sealer that includes a stationary heated block and a hot air blower spaced from the heated block. The film structure is momentarily stopped at the stationary heat sealer with hem disposed between the heated block and the hot air blower. While the film structure is stopped, the hot air blower blows heated air onto the hem to force the hem against the heated block, thereby sealing the drawtape to the hem.

Method and apparatus for sealing a drawtape to a hem of a thermoplastic film structure

An improved thermoplastic film heat bonding apparatus includes a heated seal bar, a support member supporting the heated seal bar for reciprocating motion against a platen and a resilient coupling between the support member and the heated seal bar to allow deflection of the heated seal bar with respect to the support member providing better conformance between the platen and the face of the seal bar contacting the platen for more uniform and repeatable heat seals. Springs are used to provide the resilient coupling between the support member and the heated seal bar. One mounting providing both resilient coupling and continuous adjustable spacing between the support member and the heated seal bar includes a bracket supporting a threaded member passed through the support member and a coil spring biasing the bracket and support member apart. The bracket is itself resiliently mounted to the heated seal bar also by compression coil springs. Further contributing to improved registration between the heated seal bars and the platen is a flexible, cantilever mounting of the platen. The heated seal bar support member is mounted on a support arm rotationally mounted at one end and biased against a cam at an opposing end. Rotation of the cam pivots the support arm back and forth reciprocating the support member and heated seal bar against the platen.

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Waverly, IL, United States of America

Gerald E Rawlings