Patent Application
20050199764
The invention relates to tubular winding cores about which various materials are wound into rolls, and methods of making winding cores, wherein the cores are configured to facilitate rolls of wound materials being axially stacked end-to-end so they remain coaxial with one another.
Web materials such as paper, plastic film, metal foil, and others, are commonly provided to web converters (e.g., printers, laminators, surface treaters, packaging manufacturers, etc.) in the form of large rolls of the material. The web material is wound about tubular winding cores, which typically are formed of paperboard. It is a common practice to ship multiple rolls of material stacked vertically end-to-end in two or more layers on a pallet. A corrugated paper or plastic separator or slip sheet is positioned between adjacent layers to prevent the rolls from rubbing together and damaging the edges of the web material. The separators or slip sheets increase the cost of shipping the web material.
The present invention provides stackable winding cores and methods for making such cores that can allow rolls of web material to be stacked end-to-end without separators or slip sheets between adjacent layers of the rolls. A stackable winding core in accordance with the invention has a male end and an opposite female end. The ends are configured in such a manner that they do not hinder or prevent the insertion of chucks or mandrels into the core for winding or unwinding of web material about the core. The male end of one core is receivable into the female end of another core so that the cores can be axially stacked end-to-end, the engagement between the ends of the cores keeping the core coaxially aligned with each other. The ends are also configured to support axial loads exerted between the cores.
The winding core can be produced in various ways. In one embodiment of the invention, a paperboard tube is produced in the usual fashion for making a winding core. The inner surface of the tube is machined at one end of the tube to increase the inside diameter and thereby produce a female end. At the opposite end of the tube, the outer surface is machined to reduce the outside diameter and thereby produce a male end that can fit into the female end of another core. In this manner, a core is produced having male and female ends, and nowhere is the inside diameter of the core less than that of the main portion of the core that extends between the male and female ends. Accordingly, chucks or a mandrel can be inserted into the core without hindrance.
In another embodiment of the invention, the winding core essentially comprises an inner tube disposed within an outer tube in an axially offset position such that an end portion of the inner tube extends out beyond the outer tube at one end, and at the other end the outer tube extends beyond the inner tube, thereby providing male and female ends. The inner and outer tubes are affixed to each other in suitable fashion to prevent relative movement between them.
The tube-in-tube embodiment can be produced by making an inner tube and separately making an outer tube, with the outside diameter of the inner tube being slightly less than the inside diameter of the outer tube. The inner tube can then be inserted into the outer tube and positioned in an axially offset position, and the tubes can be affixed to each other to prevent relative movement between them. Alternatively, in the case of a spirally wound paperboard winding core, a plurality of inner plies can be wound about a mandrel and adhered together to form an inner tube, and a plurality of outer plies can be wound about the inner tube and adhered together to form an outer tube surrounding the inner tube, while the interface between the tubes is free of adhesive. The resulting tube assembly can then be cut to the appropriate length for the core and the inner tube can be slid into an axially offset position with respect to the outer tube and the tubes affixed together to prevent relative movement.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some but not all embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The female end 14 has an inside diameter greater than the diameter of the cylindrical inner surface 18 of the main portion 16. The male end 12 has an outside diameter less than that of the main portion and less than the inside diameter of the female end 14 such that the male end of the core is insertable into the female end of another said core as shown in
Preferably, the core nowhere has an inside diameter less than the diameter of the cylindrical inner surface 18 of the main portion. This enables winding chucks or mandrels to be inserted into the core without interference.
The male and female ends can be created in various ways. In one embodiment, as illustrated in
Each of the male and female ends defines at least one surface, referred to herein as a “stacking surface”, for bearing axial compressive loads exerted between two cores having their respective male and female ends engaged as in
In other embodiments (not shown), the male end can be longer than the female end, in which case the first stacking surfaces 22, 26 will abut but the second stacking surfaces 24, 28 will be spaced apart when the male end is fully inserted into the female end. Alternatively, the male end can be shorter than the female end, in which case the second stacking surfaces will abut while the first stacking surfaces will be spaced apart. Preferably, however, as noted above, the male and female ends have the same length so that both pairs of stacking surfaces abut, thereby providing maximum total surface area for bearing axial loads between the cores.
As noted, the above-described core can be manufactured by first producing a paperboard tube and then machining the opposite ends to form the male and female ends. In alternative embodiments of the invention, described below in connection with
The tube-in-tube core can be produced, in one embodiment, by separately making the inner tube and the outer tube, of appropriate lengths and diameters, and then inserting the inner tube into the outer tube and affixing the tubes together. The outer diameter of the inner tube preferably is slightly less than the inner diameter of the outer tube so that the inner tube can be inserted into the outer tube without interference therebetween.
In an alternative embodiment, the tube-in-tube core is constructed by a “slip ply” technique in a spiral winding process, as now described with reference to
A plurality of outer plies 210, 212, 214, 216 are wound atop the inner plies. Adhesive is applied to the outer surfaces of plies 210, 212, and 214, so that the plies 210, 212, 214, 216 are adhered together to form an outer tube surrounding the inner tube on the mandrel. However, there is no adhesive between plies 208 and 210. Accordingly, these plies can slip relative to each other. Thus, the inner tube formed by plies 202-208 can slip relative to the outer tube formed by plies 210-216.
The composite tube formed on the mandrel is cut at a cutting station into appropriate lengths for forming cores.
The stackable winding cores in accordance with the invention allow rolls of web materials to be stacked to create multiple layers on a pallet, as shown in
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
