Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture
Reexamination Certificate
1998-09-08
2001-02-06
Watkins, III, William P. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including aperture
C428S081000, C428S121000, C428S122000, C264S145000, C264S153000, C264S155000, C264S156000, C206S397000, C206S398000, C206S400000, C206S453000, C206S586000
Reexamination Certificate
active
06183840
ABSTRACT:
FIELD OF INVENTION
This invention relates to a plastics packaging strip intended for use in protecting the edges of articles and in particular articles with curved surfaces.
SUMMARY OF THE INVENTION
The present invention has particular application for use in protecting the edges of rolls of metal sheet but it should be appreciated that the invention has application for use with other articles especially where such articles have-ourved outer or inner surfaces. The invention will hereafter be described with reference to its use in protecting the edges of a roll of sheet metal but it will be appreciated that the invention is not so limited.
Rolls of sheet metal are notoriously difficult to transport from their place of manufacture to the end user. They are large, heavy and have exposed edges. When transported, it is generally necessary to secure the rolls to the tray of a semi trailer or the like using chains which are passed through the centre of the roll and secured to the tray. The exposed edges of the rolls of steel sheet have in the past been the subject of significant damage and a number of different alternative methods have been proposed for better protecting the rolls of sheet metal and these have included both metal and plastic edge strips.
One particular solution previously proposed has been the use of a flexible plastic edge strip having a series of tabs integrally attached and hinged to a covering portion generally of uniform width. A groove provided in the plastic strip at the junction between the tabs and the covering portion of the strip has provided the necessary hinging to enable the tabs to be disposed in a position perpendicular to the covering portion.
When the tabs are disposed in a position perpendicular to the covering portion the plastic strip may be curved around the outer edge of the article to be protected and the perpendicular tabs can move towards each other when the plastic strip is formed into the shape of the roll. An example of such a flexible plastic strip is disclosed in Australian patent specification 653,868.
It is preferred when making a plastic edge strip of the kind shown in Australian patent specification 653,868 that the strip be formed from an extruded plastics material. Most preferably, the strips are manufactured from an extruded plastics sheet in which two or more edge strips are formed from a single extruded sheet. In this method of manufacture a number of grooves are formed longitudinally along the sheet. The sheet is then cut into a number of strips so to provide a plurality of edge strips from the one extruded sheet and adjacent each of the grooves respective tab formations are formed, usually by a punching operation.
Whilst this method of production facilitates manufacture of multiple strips from one sheet of material, it has been found that the product once cut into strips may not always retain the desired profile. It is not entirely clear why this happens but the applicant believes that the thermoplastic material from which the packaging strips are formed retain stresses inherent in an extrusion process and that after cutting and subsequent cooling of the product, these stresses are to some extent released resulting in a bowing. This bowing or warping normally manifests itself by the product bowing inwardly along the tab edge and bowing outwardly along the non tab or covering portion edge. This unexpected bowing of the product impinges on its utility for use along a straight edge of a curved product such as the straight edge of a roll of sheet metal.
Surprisingly, it has been discovered that the propensity of the packaging strip to warp or bow after it has been separated into a unitary structure is reduced if the non tab side of the packaging strip is perforated so to include a plurality of holes, especially if such holes are located proximate to the edge of the packaging strip on the opposite side to that including the tabs.
Thus, in accordance with a first aspect of the present invention there is provided an extruded plastics strip adapted for use in protecting the edge of an article having a curved surface; said strip including a longitudinal groove, a flexible covering portion extending from one side of the longitudinal groove adapted to be placed over and conform with the curved surface of an article to be protected and a plurality of tabs hinged to and extending from the other side of the longitudinal groove; wherein said covering portion includes a plurality of holes which are located at or proximate the outer most edge of the covering portion.
Preferably the tabs are spaced from each other such that there is a gap between adjacent tabs proximate the groove end of the tabs. Most preferably this gap increases in width between the respective adjacent tabs as they extend away from the groove.
The holes in the covering portion are believed to balance (at least in part) the effect of the cut out portions between the tabs on the manner in which the strip responds when cooling and to reduce the extent to which the extruded plastics strip will bow or warp.
The holes formed at or proximate the edge of the covering portion of the packaging strip can extend so to include part of the edge of the strip (in which case the edge will have a number of cut away sections) but preferably they are close to but do not extend all the way to the edge of the covering portion. The holes may be of any shape but they are preferably circular. This shape is believed to be the optimum shape for stress relief within the plastic material.
The holes are preferably located so that the ratio of the distance from the edge of the covering portion to the closest edge of the holes: the width of the covering portion from its edge to the longitudinal groove is 0.15 or less. Most preferably it is 0.10 or less.
Where the intended purpose of the packaging strip is to protect the edges of rolls of metal sheet it is preferred that the packaging strip include a covering portion between 75-100 mm wide and that the closest edges of at least some of the holes to the edge of the covering portion be no more than 15 mm from the edge of the covering portion. In a particularly preferred embodiment for use in protecting rolls of metal sheet the covering portion is approximately 90 mm wide and the closest edges of at least some of the holes are no more than 10 mm from the edge of the covering portion.
In a further embodiment of the invention the covering portion includes holes of at least two different sizes with the smaller holes being closer to the edge of the covering portion. In this manner, larger holes can be provided in a central portion of the covering strip so to minimize material use and the smaller holes can be located proximate the edge of the covering portion (to reap the benefits of the invention) but spaced sufficiently apart to maintain adequate stiffness along the edge.
Thus, in accordance with this aspect of the invention there is provided an extruded plastics strip adapted for use in protecting the edge of an article having a curved surface; said strip including a longitudinal groove, a flexible covering portion extending from one side of the longitudinal groove adapted to be placed over and conform with the curved surface of an article to be protected, and a plurality of tabs hinged to and extending from the other side of the longitudinal groove; wherein said covering portion includes holes of at least two different sizes.
Preferably the smaller holes are located closer to the edge of the covering portion than are the larger holes. Most desirably the covering portion of the packaging strip includes a first row of smaller holes which are located closest to the edge of the covering portion and a second set of larger holes located in the central section of the covering portion. Most preferably the second set of larger holes is formed from two rows of circular apertures arranged in a chequer board type pattern in which the holes in one row are offset from the holes in the second row. Preferably, the smaller holes are located proximate to the edge of the coverin
Nylex Corporation Limited
Watkins III William P.
Wolf Greenfield & Sacks P.C.
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