Patent Application
20080203132
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 a guide roller assembly which includes an outer layer of resiliently deformable material to accommodate irregularities in the associated film web, thereby promoting efficient and precise web handling.
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.
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.
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.
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.
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
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
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.
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
In comparison, guiding the film web with a zipper assembly over the guide roller assembly 14 of the present invention, as illustrated in
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.
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.
