Apparatus and method for securing a zipper closure to polymeric film
A method and apparatus for securing a zipper closure to polymeric film using minimal tension on the zipper closure includes providing first and second tension control loops, an eyemark detector, and a hole punch programmed to punch a hole in the zipper closure upon detection of the eyemark. The zipper closure and the film are supplied to a sealing station at the same speed, and the hole zipper closure is aligned with the eyemark on the film, to result in sealing the strip of zipper closure to the film resulting in minimal wrinkles to the resulting bag.
1. A method of securing a zipper closure to polymeric film using minimal tension on the zipper closure; the method comprising:
(a) paying out a continuous strip of plastic zipper closure from a roll of zipper closure;
(b) paying out the polymeric film from a film roll, the polymeric film having periodic eyemarks thereon;
(c) passing the strip of zipper closure through a tension control mechanism;
(d) passing the strip of zipper closure through a first tension control loop;
(e) advancing the film toward a sealing station and past an eyemark detector to detect an eyemark on the film;
(f) after detection of the eyemark on the film, punching a hole into the strip of zipper closure upon detection of the eyemark on the film;
(g) passing the strip of zipper closure with a punched hole through a second tension control loop;
(h) supplying the strip of zipper closure to the sealing station while simultaneously supplying the film to the sealing station at the same speed as the strip of zipper closure;
(i) aligning the hole in the strip of zipper closure with the eyemark on the film; and
(j) sealing the strip of zipper closure to the film.
2. The method of claim 1 wherein the step of passing the strip of zipper closure through the tension control mechanism includes passing the strip of zipper closure through a dancer mechanism.
3. The method of claim 1 wherein the step of sealing includes sandwiching the strip of zipper closure between two walls of the film and using heated sealing bars to transfer heat to the strip of zipper closure and the film.
4. The method of claim 3 wherein the step of sealing includes using 3 sets of opposing sealing bars.
5. The method of claim 3 wherein the step of sealing includes using opposing sealing bars, with a first bar of the opposing sealing bars controlling sealing pressure and a second bar of the opposing sealing bars controlling distance between the sealing bars.
6. The method of claim 1 further comprising:
(a) detecting a position of the eyemark:
(b) detecting a position of the hole;
(c) comparing a distance between the detected position of the eyemark and the detected position of the hole to a predetermined target value; and
(d) if the distance is not equal to the target value, adjusting a length of an index distance so that the distance becomes equal to the target value.
7. The method of claim 1 wherein the step of passing the strip of zipper closure through the first tension control loop includes threading the strip of zipper closure under a weighted disk movable up and down by gravity to provide constant tension to the strip of zipper closure.
8. The method of claim 1 wherein the step of passing the strip of zipper closure through the second tension control loop includes threading the strip of zipper closure under a weighted disk movable up and down by gravity to provide constant tension to the strip of zipper closure.
9. The method of claim 1 wherein, after the step of detecting the eyemark on the film, folding the film.
10. The method of claim 1 wherein the step of sealing includes using multiple sets of opposing guide rollers to guide the position of the strip of zipper closure relative to the film.