US 5,666,788 AGranted

Method for transverse sealing of film wrapped around a product

AssigneeOssid Corporation

InventorSidney S. Tolson

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Abstract

A method for heat sealing a film with a smooth seam which extends the transverse width of a wrapped package utilizes a mechanism having a cool clamping portion and a hot sealing portion which are sequentially actuated. The clamping portion, with segments upstream and downstream of a sealing position, is activated to firmly hold the film. The sealing portion is located between the upstream and downstream segments of the clamping portion. The heated sealing portion is brought into very brief, instantaneous contact with the film and retracted, leaving the clamping portion in contact with the film for a comparatively long time to allow longitudinal film shrinkage and prevent transverse film shrinkage of the film. Lastly, the clamping portion separates and the next package in a succession of film-enclosed packages is moved downstream of the sealing position.

Claims7

Dependent claims

A method for sealing and parting longitudinally extending heat shrinkable film transversely between successive film wrapped products with a sealing mechanism, comprising the steps of:

(a) clamping said heat shrinkable film transversely at a position upstream and a position downstream of a transverse sealing position;
(b) substantially instantaneously after said clamping has been initiated contacting said heat shrinkable film at said sealing position with a transverse heated sealing bar at a first sufficient temperature and under sufficient pressure to cause said film within a first period of milliseconds to seal and part so that a first of said successive products separates from a second such product;
(c) rapidly removing said sealing bar from said sealing position immediately following the expiration of said first period of milliseconds;
(d) allowing for a second period of milliseconds substantially greater than said first period of milliseconds said clamped heat shrinkable film upstream and downstream of said sealing position to shrink in a longitudinal direction away from said sealing position while restraining transverse shrinkage thereof;
and
(e) after expiration of said second period of milliseconds unclamping said heat shrinkable film;
and
(f) repeating said sequence of steps after a third period of milliseconds substantially equal to said second period of milliseconds.

5 more elements

Dependencies are inferred from the claim text.