GB2254038A

GB2254038A - Zipper insertion

Info

Publication number: GB2254038A
Application number: GB9111042A
Authority: GB
Inventors: James Ronald Johnson
Original assignee: AMI Industries Inc
Current assignee: AMI Industries Inc
Priority date: 1991-03-25
Filing date: 1991-05-22
Publication date: 1992-09-30
Anticipated expiration: 2011-05-22
Also published as: GB2254038B; GB9111042D0

Abstract

A zipper applicator (20) is placed in conjunction with a plastics bag form-and-fill machine. The bag material is diverted (18, 19) from the normal path in the form-and-fill machine, to the zipper applicator (20). The bag material is folded by a V-board (22) and held, and a length of reclosable zipper (26) is inserted close to the fold (66). The zipper (26) is hold relative to the bag material, while the area of the zipper is engaged with sealing bars (40) for sealing the zipper to the bag material. The bag material passes over a V-board (31) to unfold the material, and the material is returned to the normal path in the form-and-fill machine. <IMAGE>

Description

ZIPPER INSERTION METHOD AND APPARATUS Field of the Invention This invention relates generally to the application of closure strips to plastic bags, and is more specifically concerned with a method and apparatus for applying a string zipper to bag material in a continuous process with a formand-fill line.

Backaround of the Invention Plastic bags and the like having molded closure strips, or zippers, are well known in the art. Such bags are typically made either by extruding bag material with the closure strips formed integrally therewith, or by providing bag material and closure strips separately, and subsequently welding them together.

The above identified copending application discloses apparatus for applying a string zipper to bag material, the string zipper having no flange for attachment of the zipper to the bag. However, the apparatus disclosed in the copending application is to produce bags that are subsequently filled, and the apparatus is not usable for form-and-fill bags wherein bags are partially formed, filled with the intended contents, and the bag is sealed, enclosing the contents.

There has been some effort to provide zippers in formand-fill bags, the object being to provide a bag that is reclosable after the bag has been opened by the consumer.

The prior art technique for placing a zipper in a form-andfill bag has required that the printed bag material be shipped to a specialized processor who fixes the zipper to the bag material, then rewinds the bag material. It will be recognized that, after the zipper has been applied, the bag material does not roll neatly, and only a small length of bag material can be placed on one roll.

The prior art technique for applying a'zipper to formand-fill bags is therefore expensive and time consuming, and undesirable in processing because of the necessity for frequently changing the roll of bag material.

Summary of the Invention The present invention includes the steps of diverting bag material in a form-and-fill line, applying a zipper to the bag material and returning the bag material to the conventional processing line The bag material, with the zipper, then goes to the form and fill station where the bag is partially formed, filled, then completed and sealed.

In the preferred embodiment of the invention, the bag material is diverted from the normal path, and folded by a V-board. A length of string zipper is fed into the fold and sealed in place, the apparatus including holding means for positioning the zipper material while the zipper is sealed to the bag material. A presealer may be used to preseal the zipper material in the areas between bags so the final side welder will form a tight seal.

After the zipper material is sealed to the bag material, the bag material may be unfolded and directed back to the conventional form-and-fill system.

Brief Description of the Drawings These and other features and advantages of the present invention will become apparent from consideration of the following specification when taken in conjunction with accompanying drawings in which: Fig. 1 is a side elevational view showing a conventional form-and-fill system having the zipper insertion apparatus of the present invention associated therewith; Fig. 2 is an enlarged, side elevational view showing the zipper insertion apparatus illustrated in Fig. 1; Fig. 3 is an auxiliary view taken substantially along the line 3--3 in Fig. 2; Fig. 4 is a highly enlarged cross-sectional view showing the sealing heads for sealing the bag material to the zipper material; and, Fig. 5 is a perspective view showing the path of the bag material through the zipper application apparatus.

Detailed Description of the Embodiment Referring now more particularly to the drawings and to that embodiment of the invention here presented by way of illustration, the apparatus shown in Fig. 1 includes a roll of bag material 10, the material being unrolled and fed to the forming and filling apparatus. The material passes through a dancer 11, and conventionally passes by a pull roll 12 driven by a motor 14. The material is then directed to the pipe 15 where the bag material is wrapped around the pipe to form a tube.

Though not shown in detail in the drawings, those skilled in the art will realize that sealing means are employed so the tube formed by wrapping the bag material around the pipe 15 is sealed together. This tube is side welded, a quantity of a product is dispensed into the tube, and the remaining side is side welded to form a complete package for the product.

Some form-and-fill machines include pull belts 16 at the sides of the tube 15. These pull belts engage the tube of bag material and assist in feeding the material downwardly as the bag material moves for side welding and filling. Some form-and-fill machines do not utilize the pull belts, but both types of machines are contemplated by the present invention, and the method and apparatus for applying the zipper are applicable to many specific styles of form-and-fill machines.

The form-and-fill machine itself is not a part of the present invention, but such machines are well understood by those skilled in the art. The above brief disclosure of the prior art form-and-fill machine is therefore thought to be sufficient for an understanding of the present invention.

Still looking at Fig. 1 of the drawings, it will be noted that the bag material is diverted from its conventional path at 18, and is carried by a series of rollers 19 to the zipper insertion apparatus generally designated at 20. The bag material passes over an entry roller 21, then around a generally conventional V-board 22 for folding the bag material. As will be discussed further hereinafter, the V-board 22 does not fold the material in half, but provides a fold that is off-center.

The folded bag material is guided by the rollers 24 and 25; and, between these two pairs of rollers, the folded side of the material (as opposed to the loose edges) receives the string zipper material 26 from a zipper unwind 28, and the zipper material 26 is held in place and sealed to the bag material at 29. After the zipper has been sealed to the bag material, an ultrasonic presealer 30 melts and flattens the zipper in the area that is to be between adjacent bags.

With the zipper 26 installed on the bag material, the bag material passes over a second V-board 31, and this second V-board 31 unfolds the bag material so the bag material is ready to return to the form-and-fill machine for completion of the normal processing. It will be understood, however, that the bag material will not be completely unfolded because the zipper 26 retains a small folded portion adjacent to the apex of the fold.

So, the bag material returns to the roller 32 and continues through the form-and-fill machine as previously discussed.

The zipper unwind 28 is not here shown in detail, but the unwind disclosed in the above identified co-pending application is to be used. That disclosure is incorporated herein by reference, and no further description should be necessary. It will also be understood that any other powered unwind that will provide the string zipper at a generally constant tension would work as well.

Attention is next directed to Figs. 2 and 3 of the drawings for a more thorough understanding of the zipper application apparatus 20. Fig. 2 is an enlarged side elevational view, and Fig. 3 is a view showing the top, or front, of the apparatus as viewed along the line 3--3.

In Fig. 2 it will be seen that the V-board 22 is pivotally carried on a shaft 34. The V-board 22 is therefore adjustable, to place the point, and the zipper guide 35, in the desired position. A turnbuckle arrangement 36 holds the set position of the V-board 22. With attention to Fig. 3 of the drawings, it will be noticed that the fold made by the V-board 22 is not centered, but is off-set from the center of the bag material. The off-set position is important for placing the zipper 26 at the desired location in the final tube that is formed by the form-and-fill machine. The precise location of the apex of the fold may therefore vary somewhat to accommodate the particular formand-fill machine.

Substantially immediately after the guide 35 for the zipper 26, the rolls 24 engage the bag material with the zipper 26 in the fold thereof. The bag material is then held by the sealing apparatus 29 as will be discussed later, and by the rolls 25. The holding is such that the zipper 26 is positioned, and is held in the desired position until the zipper is sealed to the bag material.

Looking especially at Fig. 3 of the drawings, the sealing apparatus 29 includes stripper plates 38 that sandwich the folded bag material therebetween. The stripper plates 38 are supported on rods 39 having springs 37 therearound so the stripper plates 38 are spring-urged together. Sealing bars 40 are carried adjacent to the stripper plates 38, the sealing bars 40 being carried on support members 41. The support members 41 are, in turn, carried by the shaft of a fluid operated cylinder 42 and guided by two guide shafts 44 sliding in bearings 45.

After the bag material leaves the sealing apparatus 29 where the zipper 26 is sealed to the bag material, the material passes by the ultrasonic sealer 30. The ultrasonic sealer 30 includes the horn 46 for directing the energy supplied by the source 48. An anvil 49 is carried on the end of the piston rod of a fluid actuated cylinder 50.

Thus, the rod of the cylinder 50 is extended, and the bag material and the zipper 26 are urged towards the horn 46.

Those skilled in the art will realize that the ultrasonic energy will melt the zipper material, and will partially flatten the zipper material 26. With this partial flattening, the side welding apparatus of the form-and-fill machine will provide a complete, secure, weld of the bag and the zipper.

The bag material, with the zipper fixed thereto, passes between the rollers 25, then is unfolded for return to the form-and-fill machine. The fold of the bag material engages the point of the second V-board 31, and the side panels of the folded bag material extend along the sides of the Vboard 31. Since the zipper 26 is now attached to the bag material, the bag material will not be completely unfolded; rather, the tip of the fold will remain folded, held in that position by the zipper 26.

To accommodate the folded portion of the bag material, the guide rollers on the exit end of the zipper application apparatus have circumferential grooves. There is a guide roller 51 having a groove 52, and an exit roller 54 having a groove 55. The grooves 52 and 55 allow the bag material to lie smoothly on the rollers in spite of the folded portion including the zipper 26.

Looking at Fig. 4 for a detailed understanding of the sealing apparatus, the stripper plates 38 are shown, and it can be seen that the stripper plates 38 define grooves 56 for receiving the zipper 26 and the bag material. With the zipper 26 held in the grooves 56, the zipper 26 cannot deviate from the intended position. The stripper plates 28 also define openings 58 which provide enough space for the sealing bars 40 to enter the stripper plates 38 sufficiently that the tips of the sealing bars 40 will engage the bag material in the area of the zipper 26.

It is very important that heat be applied to the bag material just sufficiently to seal the bag material to the zipper 26 without degrading the bag material. Degradation of the bag material may cause leaking of the completed bag, hence possible spoilage of the contents of the bag.

Realizing that the temperature of the sealing bar itself may be quite high, the sealing tips 59 are covered with a non stick heat shield 60. The shield 60 is here disclosed as a sheet of plastic material held to the sealing bar 40 by clamps 61. Those skilled in the art may determine numerous materials that are usable as the heat shield 50, but it has been found that sheets of polytetraflouroethylene (e.g.

"Teflon") work quite well.

With the above and foregoing description in mind, operation of the method and apparatus of the present invention should be understandable. A roll of bag material 10 is mounted for feeding into the apparatus, the material passing over appropriate rolls, and being pulled through the apparatus by the drive rolls 12. Those skilled in the art will understand that the bag material is driven in a stopstart mode, the material being advanced sufficiently to form one bag, then stopping for the apparatus to perform the intended function. The bag material is then moved one more bag length, etc.

The bag material is diverted from the usual form-andfill apparatus and carried to the zipper application apparatus 20, where the bag material is folded, a length of zipper material is inserted into the fold, and the zipper material is held in position while the sealing bars 40 engage the bag material and apply enough heat to seal the bag material to the zipper. It should also be understood that, with the heat shield 60 between the sealing bars 40 and the bag material, the sealing bar can engage the same area of the bag material twice without causing enough degradation to damage the resulting bag. Thus, if the sealing bar 40 overlaps a previous seal, no harm is done.

After the zipper 26 is sealed to the bag material, the bag material is unfolded and put back into the normal process of the form-and-fill machine. The bag material is wrapped around the pipe 15 to form a tube, the tube is sealed together, and the tube is side welded, filled, and side welded again to form a completed bag. The steps are continuously repeated to form successive bags.

Fig. 5 of the drawings illustrates the path and conformation of the bag material as the bag material passes through the zipper application apparatus. The flat sheet enters at 65 and passes over the entrance roller 21 to extend behind the V-board 22. The material is then conformed to the V-board 22 and has a lower apex 66 and side panels 68 and 69. The side panels 68 and 69 are then gathered by the rolls 24 so the side panels are generally parallel. At this point, the zipper 26 is directed between the panels 68 and 69, and sealed thereto as was discussed above.

At the exit end of the apparatus 20, the side panels 68 and 69 are separated to pass around the opposite edges of the second V-board 31. The apex 66 remains folded because of the zipper 26, but the majority of the sheet of bag material is flattened out to exit from the apparatus as indicated at 70. The grooves 52 and 55 allow the folded portion to pass through without distorting the material.

It will of course be understood by those skilled in the art that the particular embodiment of the invention here presented is by way of illustration only, and is meant to be in no way restrictive; therefore, numerous changes and modifications may be made, and the full use of equivalents resorted to, without departing from the spirit or scope of the invention as outlined in the appended claims.

Claims

1. The method of producing reclosable bags, in a formand-fill machine wherein thermoplastic sheet material is fed from a supply of material (10), said material is moved along a path, and said sheet material is subsequently wrapped around a pipe and sealed to form a tube (15), the tube is side welded, a quantity of a product is passed through said pipe and placed into the tube, and the tube is again side welded above said quantity of a product, said method including the steps of diverting said sheet material from said path, folding said sheet material, inserting a thermoplastic zipper (26) into the folded sheet material, heat sealing the zipper to the sheet material, unfolding the sheet material, and returning the sheet material to said path.

2. The method as claimed in claim 1, wherein the said step of inserting a thermoplastic zipper into the folded sheet material includes the steps of feeding a continuous length of said zipper at a constant tension into the folded sheet material for maintaining the location of said zipper with respect to said material, and including the step of continuing the step of holding said zipper and said sheet material during the said step of heat sealing the zipper to the sheet material.

3. The method as claimed in claim 2, wherein the formand-fill machine utilizes stop-start feeding of said material, said method including the steps of engaging said material in the area of said zipper with heated seal bars (40) after said material is stopped, and removing said seal bars (40) from said material before said material starts again.

4. The method as claimed in claim 3, and further including the step of flattening said zipper in the area between adjacent bags prior to the said step of unfolding the sheet material, and performing the side welding of said tube in said area between adjacent bags.

5. In a form-and-fill apparatus having a supply of thermoplastic sheet material (10), a path for said sheet material from said supply to a filling station, and means (12,14) for moving said sheet material along said path, the combination therewith of zipper application means (20), diverting means (18,19) for diverting said material from said path to said zipper application means (20), said zipper application means (20) including folding means (22) for folding said material longitudinally so that said material has an apex (66) of the fold, a zipper unwind (28) for supplying a continuous length of thermoplastic zipper (26), guide means (35) for guiding said zipper (26) into the folded material adjacent to said apex (66), and sealing means (29) for sealing said zipper (26) to said folded material, and unfolding means (31) for substantially unfolding said material.

6. In a form-and-fill apparatus as claimed in claim 5, the improvement including a presealer (30) adjacent to said apex (66) for melting selected areas of said zipper (26) after said zipper has been sealed to said material.

7. In a form-and-fill apparatus as claimed in claim 6, the improvement wherein said sealing means (29) includes a pair of opposed stripper plates (38) for receiving said folded material therebetween, said stripper plates (38) defining grooves (56) therein for receiving and holding said zipper (26), and opposed sealing bars (40) selectively movable towards and away from said folded material.

8. In a form-and-fill apparatus as claimed in claim 3 the further improvement including a heat shield (60) fixed to said sealing bars (40), the arrangement being such that said heat shield (60) directly engages said material and heat is applied from said sealing bar (40) through said heat shield (60).

9. In a form-and-fill apparatus as claimed in claim 8, the improvement wherein said folding means (22) comprises a first V-board (22), said guide means includes at least one pair of rollers (24,25) for engaging the folded material, and said unfolding means (31) comprises a second V-board (31), said sealing means (29) being located between said first V-board (22) and said second V-board (31).