Vacuum seal bar
AssigneeMobil Oil Corporation
InventorsEdward A. Colombo, Gordon V. Sharps, Jr.
Life of this patent
Estimating the term…
Abstract
Disclosed are an apparatus and method for cutting and sealing a plastic film. The plastics film is conveyed to a sealing area which contains a sealing wire in a housing over which the plastics film is draped out of contact with the wire. The wire is preheated to a first temperature and is then heated to a second higher temperature while a differential pressure is applied to the film biasing it towards and into contact with the wire which cuts and heat seals it. By providing the heat sealing area in the outer periphery of a rotatable drum to which a continuous film is conveyed, a continuous cutting and heat sealing process can be achieved.
Claims29
A method for cutting and heat sealing a plastic film comprising the steps of:
- heating a cutting and sealing wire to a first predetermined temperature;
- conveying a plastic film to and over a sealing area, said sealing area overlying said cutting and sealing wire;
- heating said sealing wire to a second predetermined temperature higher than the first;
- and,
- applying a first differential pressure to said film biasing it toward and into contact with said sealing wire during the time said wire is heated to said second predetermined temperature, causing said wire to cut and seal said plastic film.
A method for cutting and heat sealing a plastic film comprising the steps of:
- conveying a plastic film as a continuous sheet into contact with a peripheral surface of a rotary drum containing a sealing area, said sealing area overlying a cutting and sealing wire, said sealing area being provided on the peripheral surface of said drum and said cutting and sealing wire extending axially of said drum and below an axially extending opening in the peripheral surface thereof;
- rotating said drum so that said cutting and sealing wire rotates and periodically underlies said film in contact with said drum periphery, said film and drum moving together;
- preheating said plastic film by heating said cutting and sealing wire to a first predetermined temperature before or during an initial period of contact of said plastic film with that portion of said drum periphery adjacent said sealing wire;
- thereafter increasing the temperature of said sealing wire to a second predetermined temperature higher than said first predetermined temperature and applying a first differential pressure during a later period of contact of said plastic film with said drum portion during the time said wire is heated to said second predetermined temperature to cut and seal said plastic film;
- and removing the cut and sealed plastic film at segments from the peripheral surface of said drum.
An apparatus for cutting and sealing a plastic film comprising:
- a support means for receiving and supporting a plastic film, said support means having an opening and a housing underlying said opening and containing a heatable cutting and sealing wire;
- means for heating said wire;
- means for applying a first differential pressure to bias a plastic film which may be placed on said support means towards and into contact with said wire;
- and
- control means for operating said heating means and first differential pressure applying means such that said wire is heated to a first predetermined temperature and is thereafter heated to a second predetermined temperature higher than the first, and said differential pressure is applied during the time said wire is heated to said second predetermined temperature.
An apparatus for cutting and sealing a plastic film comprising:
- a rotatable drum for receiving and supporting a plastic film, said rotatable drum having an opening and a housing underlying said opening and containing a heatable cutting and sealing wire, said housing being located below and extending axially of and along a portion of the outer peripheral surface of said rotatable drum, said wire extending axially of said rotatable drum in said housing and being spaced below said opening in the peripheral surface of said rotatable drum;
- means for heating said wire;
- means for applying a first differential pressure to bias a plastic film placed on said rotatable drum towards and into contact with said wire;
- and
- control means for operating said heating means and first differential pressure applying means such that said wire is heated to a first predetermined temperature and is thereafter heated to a second predetermined temperature higher than the first, and said first differential pressure is applied during the time said wire is heated to said second predetermined temperature.
An apparatus as in claim 24, further comprising first conveying means for conveying a plastic film to the outer peripheral surface of said rotatable drum and second conveying means for conveying cut and sealed plastics film segments away from the outer peripheral surface of said rotatable drum.
Dependencies are inferred from the claim text.