Intermittently translating draw tape stretched between nip rolls
AssigneeMobil Oil Corporation
InventorFox J. Herrington
Life of this patent
Estimating the term…
Abstract
A thermoplastic tape having thick and wide end portions with a relatively thin and narrow stretched central portion between them is produced by a first pair of nip rolls running at a slow speed, and a second pair of nip rolls running at a higher speed. The tape between the nip rolls is intermittently moved away from, and toward said first nip rolls to stretch it to produce the relatively thin and narrow central portion. The second pair of nip rolls is mounted on a pivoted arm so that they are movable toward, and away from said first nip rolls. Alternatively, an idler roll between the two pairs is moved toward, and away from, the first nip rolls.
Claims14
Apparatus for forming a thermoplastic tape having thick and wide end portions with a relatively thin and narrow central portion between the end portions in combination with thermoplastic bag making machinery comprising:
- a first pair of nip rolls running at a relatively slow tape propelling speed;
- a second pair of nip rolls positioned for receiving a tape fed along a path from said first pair of nip rolls and running at a higher tape propelling speed;
- means associated with said two pairs of nip rolls for intermittently lengthening the tape path between said two pairs of nip rolls from an original length to stretch a tape between the pair of nip rolls to produce said relatively thin and narrow central portion and for returning said tape path to said original length to produce unstretched end portions;
- means in said bag making machinery associated with said second pair of nip rolls for receiving a draw tape from said second pair of nip rolls and inserting said draw tape into a folded hem of a continuous line of thermoplastic bags;
- and
- means in said bag making machinery for heat sealing said draw tape to said folded hem through said thick and wide end portions of said draw tape.
The method of intermittently stretching a thermoplastic tape to produce a draw tape having a relatively thin and narrow central portion between thick and wide end portions and inserting the draw tape into a folded hem of a continuous line of thermoplastic bags comprising:
- passing a continuous thermoplastic tape along a a path between a first pair of nip rolls running at a relatively slow tape propelling speed and a second pair of nip rolls running at a higher tape propelling speed;
- intermittently lengthening the tape path between said two pairs of running nip rolls thereby stretching said thermoplastic tape and producing said relatively thin and narrow central portion;
- returning said tape path to an original length thereby producing said unstretched thick and wide end portions;
- receiving a draw tape from said second pair of nip rolls and inserting said draw tape into a folded hem of a continuous line of thermoplastic bags;
- and
- heat sealing said draw tape to said folded hem through said thick and wide end portions of said draw tape.
Dependencies are inferred from the claim text.