Web-handling apparatus including guide roller assembly with resiliently deformable outer layer

Abstract

A web-handling apparatus includes at least one guide roller assembly having an inner, cylindrical core, and an outer layer affixed thereto. Notably, the outer layer of the roller assembly comprises resiliently deformable material, with polyurethane foam having proven to be particularly suitable for this application. By this arrangement irregularities in an associated film web, such as in the form of side gussets and/or zipper fastener assemblies, are readily guided by the roller assembly while avoiding wrinkling or other stress of the associated film web.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. Ser. No. 11/711,964, filed Feb. 28, 2007, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to apparatus for handling film webs, such as in connection with manufacture of bags or pouches, and more particularly to a web-handling apparatus including one or more guide roller assemblies which includes an outer layer of resiliently deformable material which can accommodate irregularities in the associated film web, and otherwise promote efficient and precise web handling.

BACKGROUND OF THE INVENTION

Apparatus are known for handling film webs, typically polymeric material, in connection with the manufacture of bags, pouches, and like articles. During manufacture of such articles, it is frequently necessary for folds and/or gussets to be formed in the film web, which can thereby result in certain portions of the web, along the longitudinal direction thereof, being thicker than adjacent portions.

Other irregularities in the thickness of a film web can result from the placement of zipper-like fastener assemblies on the web, typically in the longitudinal direction thereof.

The irregularities in film thickness which typically result during manufacture of bags and the like can be problematic, in that wrinkles can undesirably form in the gusset, or at a portion of the film web where the size and position of the gusset changes. Such problems typically occur when an already gusseted film web wraps around a roller for more than about 45 degrees of the circumference.

Heretofore, these problems typically encountered during web handling have been addressed by using idler rollers that are abnormally large, such as on the order of 8 to 12 inches in diameter, or by employing fluted rollers. However, both of these methods entails certain drawbacks. Relatively large rollers can be quite expensive, particularly when compared to a typical roller having a 4-inch diameter. Additionally, large rollers undesirably add significant rotational inertia to the web-handling apparatus. Fluted rollers are also more expensive than typical 4-inch rollers, and they may also add more rotational inertia to the apparatus. Additionally, fluted rollers can undesirably mark or crease the film web, and experience has shown that fluted rollers are not always effective for handling some types of film material.

Another problem associated with handling of film webs concerns the extensibility of the web as it is moved, such as between successive rollers and a web-handling apparatus. The extensibility of the web can undesirably detract from precise handling, and can in some instances mandate use of relatively expensive servo-operated nip-rolls, in order to achieve the necessary level of web-handling precision.

The present invention is directed to an improved web-handling apparatus having at least one guide roller which is configured to facilitate efficient and precise handling of film webs, including those having irregularities, such as folds, gussets, and/or zipper assemblies.

SUMMARY OF THE INVENTION

The present invention is directed to a web-handling apparatus comprising at least one guide roller assembly about which an associated film web is guided. In accordance with the preferred form of the present invention, the guide roller assembly includes an outer layer of resiliently deformable material, which in a presently preferred embodiment, comprises polyurethane foam. By virtue of the resiliently deformable nature of the outer roller material, irregularities in the film thickness are readily accommodated, while avoiding undesired wrinkling or the like in the film web. Efficient and precise web handling is thus facilitated, with the construction providing a desirable combination of support and “forgiveness” to promote wrinkle-free web-handling.

Additionally, a web-handling apparatus embodying the principles of the present invention can include a plurality of guide roller assemblies having resiliently deformable outer surfaces, with the guide roller assemblies desirably cooperating to create a “tension zone” within which the extensibility of the web is held in check and controlled by resilient deformation of the guide roller assemblies. Excessive stretching of the film web is thus desirably avoided.

Another aspect of the present invention concerns configuring the guide roller assembly of the web-handling apparatus so that the resiliently deformable outer layer thereof has a width greater than the width of the associated film web. This desirably acts to create relatively uncompressed regions of the outer layer, at respective opposite margins of the film web, which regions desirably act to flatten the film web across the guide roller assembly.

A further aspect of the present apparatus relates to providing a dancer roller arm, mounted for pivotal movement, upon which the guide roller assembly is mounted for rotation about its rotational axis. By this arrangement, the rotational axis, and thus the guide roller assembly, is movable through an arc attendant to intermittent motion of an associated film web, with the resiliently deformable outer surface of the guide roller assembly desirably acting to absorb sudden tension loads exerted on the film web.

In the disclosed embodiment, the polyurethane foam material is affixed to an inner, cylindrical core of the roller assembly, with the core preferably comprising aluminum. In a presently preferred embodiment, the polyurethane foam comprises open-celled foam, with a most preferred form comprising about 80% open-celled foam. A material which exhibited particularly desirable performance exhibits a Compression Load Deflection of about 25% at 4 to 7 percent per square inch (psi).

Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a web-handling apparatus including a guide roller assembly embodying the principles of the present invention;

FIG. 2 is a diagrammatic, cross-sectional view of the guide roller assembly illustrated in FIG. 1, illustrating handling of a gusseted film web;

FIG. 3 is a diagrammatic view of a side-gusseted film web;

FIG. 4 is a diagrammatic view of a film web having a zipper assembly applied thereto, illustrating the effect of this type of irregularity on the film web when positioned in association with a conventional guide roller assembly;

FIG. 5 is a diagrammatic view illustrating the guide roller assembly of the present web-handling apparatus handling a film web with a zipper fastener assembly applied thereto;

FIG. 6 is a diagrammatic view of the present guide roller assembly illustrating handling of the film web having a zipper fastener assembly applied thereto;

FIG. 7 is a diagrammatic view of a pair of guide roller assemblies configured in accordance with the present invention, wherein a tension zone is created in the film web between the guide roller assemblies;

FIG. 8 is a diagrammatic view illustrating resilient deformation of a guide roller assembly configured in accordance with the present invention, with the arrangement desirably facilitating flattening of the associated film web; and

FIG. 9 is a diagrammatic view illustrating use of the guide roller assembly of the present invention in association with a dancer roller arm of the associated web-handling apparatus.

DETAILED DESCRIPTION

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings, and will hereinafter be described, a presently preferred embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiment illustrated.

With reference to FIGS. 1 and 2, therein is illustrated a web-handling apparatus including at least one guide roller assembly 10 embodying the principles of the present invention. Guide roller assembly 10 is mounted for rotational movement about a rotational axis A, with the roller assembly typically mounted by way of suitable bearing assemblies, as are known in the art. The size of the roller assembly can be varied while keeping with the principles disclosed herein, but in a typical web-handling apparatus, the roller assembly may have a diameter on the order of about 3 to 4 inches.

In accordance with the present invention, the roller assembly 10 includes an inner, cylindrical core 12, and an outer layer 14 affixed to the cylindrical core. For low rotational inertia and cost-effective use, the cylindrical core 12 is preferably formed from aluminum, although other materials can be employed without departing from the present invention.

In accordance with the present invention, the outer layer 14 of the roller assembly comprises resiliently deformable material, preferably polyurethane foam. Notably, the provision of such a material has been found to greatly facilitate handling of an associated film web, W, such as comprising gusseted film (see FIG. 3). As will be recognized by those familiar with the art, a film web of this nature exhibits irregularities in the form of variations in thicknesses across the width of the film, typically along the longitudinal direction thereof. Inwardly extending side gussets, folds, and other irregularities can undesirably induce wrinkling or the like attendant to web-handling, particularly when the film web is guided about an associated roller assembly for more than about 45 degrees of its circumference.

Not only has the use of polyurethane foam for the outer layer 14 have been found to provide the desired resilient deformability for the roller assembly, this type of material is quite durable, and exhibits a negligible amount of added rotational inertia, thus facilitating web handling by permitting the apparatus to readily change rotational speeds, as may be typically required during operation.

In a current embodiment, polyurethane foam exhibiting a specified Compression Load Deflection (CLD) has been successfully employed. Measurement of CLD entails positioning of a 4-7 pound weight placed on a 1-inch cube of the foam material, which will compress it to 25% of its original thickness. Thus, under this loading, the 1-inch cube flattens out to a thickness of about 0.75 inches, so the foam is given a 4-7 psi, 25% CLD rating.

In a current embodiment, an aluminum roller having a diameter of 3 inches, and a 0.047 inch wall thickness at any face width, has been employed for the inner cylindrical core 12, with a foam coating 14 affixed thereto having a 0.125 inch thickness. A polyurethane foam material available from American Roller, under the product designation Pegasus, PN 200, has been successfully employed. This material is a combination of about 20% closed cell foam and 80% open-cell foam, although the percentage of opened/closed cells can be varied while keeping with the principles disclosed herein. Additionally, while use of foam material is presently preferred, it will be recognized that the outer layer of the present guide roller can be provided in the form of other suitably resiliently deformable materials.

FIG. 2 is a diagrammatic view illustrating the manner in which a gusseted film web can resiliently deform the outer foam layer 14 of the present guide roller assembly, while the outer film layer of the web remains tightly wrapped without stretching, as the foam material allows the inner film layers to deform without wrinkling.

An additional benefit of the present invention is that it solves problems typically associated with running a web of film material that has one or more zipper-like fastener assemblies secured thereto. The present invention provides a distinct improvement over grooved or otherwise relieved rollers. The foam covered roller of the present invention supports the film on both sides of the zipper, and still desirably holds the zipper assembly in place and in-line. The result is the film near the zipper is under less stress, with the deformable outer layer automatically providing a region of relief for the fastener assembly.

This is diagrammatically illustrated in FIGS. 4, 5, and 6. FIG. 4 illustrates a film having a zipper assembly Z secured thereto, when drawn about a conventional roller R having a relatively non-deformable outer surface.

In comparison, guiding the film web with a zipper assembly over the guide roller assembly 14 of the present invention, as illustrated in FIG. 5, desirably permits the zipper assembly to sink into and resiliently deform the outer foam layer 14, without placing undue stress on the film material (FIG. 6).

A further virtue of the presently preferred polyurethane foam material, such as described above, is that the machine can be readily machined as may be required for guide roller formation.

With reference to FIG. 7, therein is diagrammatically illustrated a web-handling apparatus of the present invention, wherein a pair of the guide roller assemblies 10 are provided for rotation on respective rotational axes A to create a tension zone Z in the film web between the guide roller assemblies.

When more than one foam-covered guide roller assembly is used to establish a tension zone, the tension between the rollers, is buffered by the foam. The foam covering does not allow the web to slip back and forth, and that is how the tension zone is established.

As will be evident from FIG. 7, the web across the foam-covered guide roller assemblies 10 has a tension that is equal to the P.L.I. (pressure per linear inch) across those roller assemblies. As more tension is applied to the web, the foam will compress. The extensibility of the web is held in check by the compliance of the foam. During web movement, the web is released to the tension zone by the upstream roller assembly, and taken up by the downstream roller assembly as it compresses. Notably, the web will not stretch until all of the available compression of the foam is used up, or the extensibility of the web is exceeded by the compression ratio of the foam. As the rollers rotate, the upstream roller delivers the film and relieves compression, while the downstream roller takes up the relieved web by compressing. In the illustrated embodiment, the axes A of the guide roller assemblies 10 are illustrated as being generally parallel to each other, but it is within the purview of the present invention that the axes may be arranged in a non-parallel orientation.

Thus, within the tension zone where folding and/or turning, or other process steps, are being performed, stretching of the web is desirably avoided, and the web does not clamp itself onto these process components. This desirable benefit of the present invention avoids the need for relatively expensive servo-activated rollers or the like.

FIG. 8 illustrates another desirable benefit of the guide roller assembly 10 of the present invention, wherein the resiliently deformable outer surface 14 of the guide roller assembly 10 has a width which is greater than the width of the associated film web W. This arrangement takes advantage of the known phenomenon wherein a film web being handled tends to “ride to a high spot” (that is, a point of high tension) on an associated roller. As will be seen in FIG. 8, the film web acts to compress the deformable outer surface of the guide roller assembly 10 on which the web is wrapped. The result is the creation of relatively uncompressed regions of the outer layer 14 at respective opposite margins of the film web W, which regions act to flatten the film web across the guide roller assembly. The result is that each edge of the film is against a “high spot”, because the web is essentially in a valley. As a consequence, each edge is pulled outwardly, and the web is desirably flattened.

FIG. 9 illustrates a further aspect of the present invention which desirably promotes efficient web handling. FIG. 9 illustrates the provision of a dancer roller arm 16 mounted for pivotal movement, with a guide roller assembly 10 mounted for rotation about an axis A, so that the axis is movable through an arc attendant to intermittent motion of an associated film web: Thus, as the dancer roller arm reciprocates back and forth as the web is intermittently indexed, the arm will, at some point, be launched by a fast, aggressive index. The resiliently deformable surface of the guide roller assembly desirably absorbs the sudden forward pull by compressing at the beginning of the forward pull. This arrangement desirably results in increased web-handling speed.

From the foregoing, it will be observed that numerous modifications and variations can be effected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiment illustrated herein is intended or should be inferred. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims.

Claims

1. A web-handling apparatus, comprising:

at least one guide roller assembly about which an associated film web is guided,

said roller assembly being mounted for rotation about an axis,

said roller assembly including an inner, cylindrical core, and an outer layer affixed to said cylindrical core,

said outer layer comprising resiliently deformable material, to thereby facilitate efficient handling of said film web.

2. A web-handling apparatus in accordance with claim 1, wherein:

said deformable material comprises polyurethane foam.

3. A web-handling apparatus in accordance with claim 2, wherein:

at least a portion of said polyurethane foam is open-celled foam.

4. A web-handling apparatus in accordance with claim 3, wherein:

said polyurethane foam comprises at least about 80% open-celled foam.

5. A web-handling apparatus in accordance with claim 1, wherein:

said cylindrical core comprises aluminum.

6. A web-handling apparatus in accordance with claim 1, wherein:

said deformable material has a Compression Load Deflection of about 25%.

7. A web-handling apparatus in accordance with claim 1, wherein:

said apparatus comprises at least two of guide roller assemblies mounted for rotation on respective rotational axes to create a tension zone between said guide roller assemblies, the tension of said film web in said tension zone corresponding to the pressure per linear inch of said film web on said guide roller assemblies.

8. A web-handling apparatus in accordance with claim 7, wherein:

said rotational axes are generally parallel to each other.

9. A web-handling apparatus in accordance with claim 1, wherein:

said outer layer of said guide roller assembly has a width greater than the width of said associated film web, to thereby create relatively uncompressed regions of said outer layer at respective opposite margins of said film web which regions act to flatten said film web across said guide roller assembly.

10. A web-handling apparatus in accordance with claim 1, wherein:

said apparatus includes a dancer roller arm mounted for pivotal movement on which said guide roller is mounted for rotation about said axis, so that said axis is movable through an arc attendant to intermittent motion of the associated film web.

11. A method of handling a film web, comprising the steps of:

providing a web-handling apparatus having a guide roller assembly; and

directing a film web through said apparatus, including guiding said film web about said guide roller assembly,

including providing said guide roller assembly with an outer layer comprising resiliently deformable material to thereby accommodate irregularities in said film web.

12. A method of handling a film web in accordance with claim 11, wherein:

said deformable material comprising polyurethane foam.

13. A method of handling a film web in accordance with claim 11, wherein:

said irregularity in said film web comprises a zipper assembly.

14. A method of handling a film web in accordance with claim 11, wherein:

said irregularity in said film web comprises a longitudinal gusset.

15. A method of handling a film web in accordance with claim 11, including:

guiding said film web about at lease 45 degrees of said roller assembly.

16. A method of handling a film web in accordance with claim 11, including:

providing a pair of said guide roller assemblies for rotation on respective rotational axes to create a tension zone between said pair of guide roller assemblies, the tension of said film web in said tension zone corresponding to the pressure per linear inch of said film web on said guide roller assemblies.

17. A method of handling a film web in accordance with claim 11, including:

providing said outer layer of said guide roller assembly has a width greater than the width of said associated film web, to thereby create relatively uncompressed regions of said outer layer at respective opposite margins of said film web which regions act to flatten said film web across said guide roller assembly.

18. A method of handling a film web in accordance with claim 11, including:

providing a dancer roller arm mounted for pivotal movement on which said guide roller is mounted for rotation about said axis, so that said axis is movable through an arc attendant to intermittent motion of the associated film web.