Package making – Closing packages and filled receptacles – By means adapted to engage outturned seam of package cover
Patent
1992-03-19
1993-09-28
Sipos, John
Package making
Closing packages and filled receptacles
By means adapted to engage outturned seam of package cover
533737, 53552, B65B 912, B65B 5130
Patent
active
052477797
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a heat sealing device useful for making pouches filled with flowable materials, e.g. thick sauces and dressings, particularly to pouches made on so-called vertical form, fill and seal machines.
It is well known to package flowable materials, for example, milk, on so-called vertical form, fill and seal machines. Using one such a machine, a flat web of synthetic thermoplastic film is unwound from a roll and formed into a continuous tube in a tube forming section, by sealing the longitudinal edges of the film together to form a so-called lap seal or a so-called fin seal. The tube thus formed is pulled vertically downwards to a filling station. The tube is then collapsed across a transverse cross-section of the tube, the position of the cross-section being at a sealing device below the filling station. A transverse heat seal is made, by the sealing device, at the collapsed portion of the tube, thus making an airtight seal across the tube. The sealing device generally comprises a pair of jaws. After making the transverse seal, but before the jaws of the sealing device are opened, a quantity of material to be packaged, e.g. liquid, is caused to enter the tube, at the filling station, and fill the tube upwardly from the aforementioned transverse seal. The tube is then caused to move downwardly a predetermined distance. Such movement may be under the influence of the weight of the material in the tube, or may be caused by pulling or mechanically driving the tube. The jaws of the sealing device are closed again, thus collapsing the tube at a second transverse section. The second transverse section may be above, usually just above, the air/material interface in the tube, or the second transverse section may be below the air/material interface. The sealing device clamps, seals and severs the tube transversely at the second transverse section. The material-filled portion of the tube is now in the form of a pillow shaped pouch. Thus the sealing device has sealed the top of the filled pouch, sealed the bottom of the next-to-be formed pouch, all in one operation. Contamination of the heat sealing surfaces of the tube may occur due to splashing or drooling of the material to be packaged. One such vertical form and fill machine of the type described above is sold under the trade mark PREPAC. Other machines may be operated such that the material-to-be-packaged is caused to enter the tube continuously rather than intermittently as described above. As a result, sealing of the film takes place with material-to-be-packaged between the heat sealing surfaces in the tube.
With some other machines, the sealing device does not sever the tube at the second transverse section, but does sever the tube subsequently. With yet other machines the jaws of the heat sealing device reciprocate up and down. With such machines, the jaws clamp, seal and sever the tube of film while moving in a downward direction, the jaws then open and return upwards in the open position. The downward movement of the closed jaws also serve to advance the tubular film downwardly.
The present invention relates to heat sealing machines in which the sealing and severing occurs in a single operation.
For many years, milk has been packaged in pouches made on vertical form and fill machines. Such pouches have been sold to household consumers and, in use, such milk-filled pouches are stood within an open-mouthed pitcher. More recently, such pouches have been used to package other flowable comestibles, mayonnaise, caramel, scrambled eggs, tomato ketchup, chocolate fudge, salad dressings, preserves and the like. Pouches containing such comestibles are usually sold to "institutional" buyers, e.g. restaurants.
A sealing device commonly used is a so-called "impulse sealer" in which an electrical current flows through the sealing element for only a fraction of the cycle time between operations. The impulse sealer may be a round wire, e.g. a "piano" wire about 2.00 mm to 2.29 mm diameter, electrically insulated from a water-cooled supporting jaw. After
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Sadler James W.
Thompson John R.
Wirsig Ralph C.
Du Pont Canada Inc.
Johnson Linda B.
Sipos John
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