BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
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:
FIG. 1 is a perspective view of a portion of a tube according to one embodiment of the present invention;
FIG. 2 is a cross-sectional view of the tube shown in FIG. 1 taken substantially along line 2-2, with the outer zone of the tube in place;
FIG. 3 is a cross-sectional view of the tube shown in FIG. 1 taken substantially along line 3-3, with the outer zone of the tube in place;
FIG. 4 is a partial plan view of an apparatus for forming a tube as shown in FIG. 1;
FIG. 5 is a cross-sectional view as in FIG. 3 of a tube according to another embodiment of the present invention; and
FIG. 6 is a cross-sectional view as in FIG. 2 of a tube according to the embodiment shown in FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
The present invention 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, this invention 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.
FIGS. 1 through 3 show a spirally wound tube 10 in accordance with one embodiment of the present invention. The tube 10 extends around and along an axis for a predetermined length from a first end to a second end. As best shown in FIG. 2, the cross-section of the tube relative to the axis defines a circumference.
As illustrated in FIG. 3, the tube includes a wall 11 having an inner zone 20, an intermediate zone 30, and an outer zone 40. The inner zone 20 is located inwardly and radially extends from an inner surface of the tube to the intermediate zone 30. The intermediate zone 30 radially extends from the inner zone 20 to the outer zone 40. The outer zone 40 is located outwardly and radially extends from the intermediate zone 30 to an outer surface of the tube. The inner surface defines an inner diameter of the tube and the outer surface defines an outer diameter of the tube. The inner and outer zones 20, 40 comprise one or more layers, and each layer in turn comprises one or more plies. For example, according to the illustrated embodiment of FIGS. 1 through 3, the inner and outer zones 20, 40, each have three layers 201, 202, 203, 401, 402, 403. Layers in the inner zone are referred to herein as inner layers and layers in the outer zone are referred to herein as outer layers due to the location of the layers. The intermediate zone 30 comprises two or more layers, and each layer in turn comprises one or more plies. For example according to the illustrated embodiment of FIGS. 1 through 3, the intermediate zone 30 has 6 layers 301-306. Each layer in intermediate zone is referred to herein as an intermediate layer due to the layer's location.
As used herein, a “layer” is a region of the tube 10 delimited by an outer radius r0 and an inner radius ri that respectively correspond to an outer surface and inner surface of a “ply” of that layer as best seen in FIG. 3. A “ply” is a unitary sheet of material that, when wound into the tube 10, constitutes at least a part of a single layer of the tube 10. Thus, in accordance with the present invention, a layer can comprise more than one ply occupying the region bound by r0 and ri.
In the illustrated embodiments, each inner layer 201, 202, 203 respectively includes one ply 2011, 2012, 2013, also referred to herein as an inner ply due to its location within an inner layer. Each inner ply 2011, 2012, 2013 is wound so that nominally it has no substantial gaps between its adjacent edges along the length of the tube 10 as generally described in U.S. Pat. No. 6,851,643. “Nominally” means that the objective is to wind the inner ply so that a perfect butt joint exists between the adjacent edges. However, in practice, a perfect butt joint may not always be achieved, and typically small gaps are inadvertently created between the edges of the ply. In general, such inadvertent gaps will be relatively small compared to the width of the plies.
Similarly, each outer layer 401, 402, 403 respectively includes one ply 4011, 4012, 4013, also referred to herein as an outer ply due to its location within an outer layer. Each outer ply 4011, 4012, 4013 is wound so that nominally it has no substantial gaps between its adjacent edges along the length of the tube 10.
It should also be noted, as further described in U.S. Pat. No. 6,851,643, it is known from geometrical considerations applicable to spiral winding that to achieve a perfect butt joint, the width of ply, the diameter of the ply, and the spiral wind angle are related. Basically, the width, the angle, or both must increase as the diameter of the ply increases. Therefore, one in the art would appreciate that either the spiral wind angle, the width of the ply, or both may vary between layers to account for the above-mentioned geometrical considerations.
In contrast to the inner layers 201, 202, 203 and outer layers 401, 402, 403, the intermediate layers 301-306 are wound such that a gap exists between consecutive turns of a ply or adjacent plies. More specifically and as stated above, each intermediate layer may include one or more plies. Plies in an intermediate layer are referred to as intermediate plies due to their location. In an intermediate layer having only one intermediate ply, a relatively wide gap is intentionally created between the adjacent edges of consecutive turns of that ply. The gap extends helically along the tube at the spiral wind angle at which the ply is wound. In an intermediate layer having more than one ply, such as in the illustrated embodiments, relatively wide gaps S are intentionally created between the adjacent plies 3011-3022 of the layers 301-306, as further discussed in U.S. application Ser. No. 11/225,547 assigned to the assignee of the present application and hereby incorporated by reference in its entirety. The intermediate plies may be substantially narrower than the outer and inner plies for forming the gaps and the intermediate plies may be “mini-plies,” as further discussed in U.S. application Ser. No. 11/225,547. (As explained further below, plies of a bridge layer may be closer in width to the outer and inner plies than to a typical intermediate ply, even though the bridge layer is in the intermediate zone.) For example, one or more of the inner and outer layers may each have one inner or outer ply, wherein the width of each the inner and outer plies is approximately 5″ and one or more of the intermediate layers may have two intermediate “mini-plies”, wherein the width of each mini-ply is approximately 1¼″, with a 1¼″ gap between the two mini-plies.
As best seen in FIG. 2, the intermediate layers are circumferentially staggered or offset from each other. Radially adjacent intermediate plies are plies that are in different intermediate layers but are adjacent to one another radially. As shown, the radially adjacent intermediate plies are staggered such that their edges are not aligned but do have at least a portion of each intermediate ply that overlaps the other ply. The overlapping portions of the intermediate plies form a continuous path of ply material from the inner zone to the outer zone, referred to herein as a “spoke.” The number of spokes within the tube may vary and corresponds with the number of plies per intermediate layer. For example, according to the illustrated embodiments, each intermediate layer 301-306 includes two intermediate plies 3011-3022 and the tube 10 includes two spokes 50, 60. One in the art should appreciate that additional spokes may be added to other embodiments of the tube. For example, the tube may have three or four spokes. In general, the numbers of spokes may be increased by decreasing the width of the intermediate plies compared to the circumference of the tube. For a particular cross-section of the tube and as shown in FIG. 2, each spoke 50, 60 extends non-radially along the circumference, i.e. the spoke extends from the inner zone 20 to the outer zone 40, with both a radial component and a circumferential component of direction. Although not evident from the cross-sectional view of FIG. 2, each spoke 50, 60 also extends helically along the length of the tube.
The spokes 50, 60 of the tube are spaced by complementary voids 70, 80 within the inner zone 20 of the tube. Circumferentially staggering or offsetting the intermediate plies 3011-3022 also circumferentially offsets the gaps S in the intermediate layers 301-306. Similar to the radially adjacent intermediate plies, radially adjacent gaps include overlapped portions relative to one another. A combination of the overlapped portions in the radially adjacent gap defines a void within the intermediate zone. In general, a void 70, 80 exists between one or more spokes 50, 60 and thus has a complementary shape to the spokes. As shown in FIG. 2, a void 70, 80 may extend non-radially from the inner zone 20 to the outer zone 30. According to the illustrated embodiment of FIG. 2, each void 70, 80 extends substantially over one half the circumference of the tube 10 and together the voids 70, 80 extend over the entire circumference of the tube 10 and portions of the voids 70, 80 circumferentially overlap each other. Also, the voids extend helically along the length of the tube.
Although the embodiment of FIGS. 1 through 3 includes one void between adjacent edges of the spokes, in other embodiments the tube may have more than one void between adjacent edges of the spokes. For example and as shown in FIGS. 5 and 6, the intermediate zone 20 may include one or more intermediate layers 311 that connect or “bridge” the spokes 50, 60, referred to herein as a bridge layer. At least one of the intermediate plies 3023 of the bridge layer is aligned and wide enough to extend across one spoke 50 to the other 60. In the illustrated embodiment of FIGS. 5 and 6, the intermediate zone 30 has four voids 71, 72, 81, 82. Two voids 71, 72 are between the adjacent edges of the spokes 50, 60 and extend from the inner zone 20 to the outer zone 40 and are divided by the bridge layer 311. Two additional voids 81, 82 are between the opposite adjacent edges of the spokes 50, 60 and extend from the inner zone 20 to the outer zone 40 and are divided by the bridge layer 311.
The bridge layer may have wider plies and different number of plies than the other intermediate layers. Also, the ply or plies of the bridge layer may be wound to have no gaps or a smaller gap than the gaps in the other intermediate layers. Therefore the plies of the bridge layer or layers may be substantially the same width as the outer and inner plies.
Another aspect of the present invention is a method or process of forming the tube 10. In general, the tube 10 is formed by spirally winding a plurality of plies about a mandrel 100, adhering the plies together, and severing portions or sections of the spirally wound plies to form individual tubes 10. FIG. 4 illustrates one method of making the paper tube 10 according to one embodiment of the present invention. The plies are drawn from respective creels (not shown) and routed along a path to the mandrel 100. Each ply may have an adhesive applied to it at an adhesive applying station (not shown) such as a glue pot for adhering to adjacent plies. The inner plies 2011, 2012, 2013 are applied to the mandrel 100 and spirally wound to form the inner layers 201, 202, 203 and thus inner zone of the tube. Downstream from the inner plies 2011, 2012, 2013, the intermediate plies 3011-3022 are applied on top of the inner zone and spirally wound to form the intermediate layers and thus the intermediate zone of the tube. More specifically, the intermediate ply or plies of a first intermediate layer are applied to the mandrel on top of the inner zone with gaps between the adjacent plies or adjacent edges of the ply. Next, the ply or plies of a second intermediate layer are applied to the mandrel on top of the first intermediate layer such that the plies of the second intermediate layer are partially offset from the plies of the first intermediate layers including having overlapping portions between the plies of the first and second intermediate layers. Additional intermediate layers may be applied including partially offsetting the plies of the subsequent intermediate layers with the plies of the preceding intermediate layers. However, in embodiments with bridge layers, the intermediate ply or plies of the bridge layers may be applied with no or a nominal gap between plies or edges. After applying the last intermediate layer and forming the intermediate zone, the outer plies 4011, 4012, 4013 are applied on top of the intermediate zone and spirally wound to form the outer layers 401, 402, 403 and thus the outer zone of the tube. A cut-off station (not shown) may be included to cut the continuous tube 15 formed by the spirally winding of the plies into discrete lengths to form individual tubes 10. A winding belt 101 rotates the continuous tube 15 in a screw fashion such that the tube 15 advances down the mandrel 100.
The non-radial spokes of the tube facilitate the transmission of torque from the inner zone to the outer zone during winding and handling operations, while insulating the inner diameter from radial pressure on the outer zone. More specifically, radial pressure on the outer zone will deform the spokes, and the voids provide an area for the movement of the voids, before affecting the inner zone or inner diameter of the tube. Therefore the spokes and voids provide an enhanced ID stiffness. Also, the spokes and voids may essentially extend around the entire circumference and length of the tube and thus provide for more consistent properties throughout the tube.
Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which this invention pertains 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.
Patent Application
20080060746
