Patent Application
20100104782
The invention relates to winding cores or tubes made by spirally winding a plurality of paperboard plies about a forming mandrel and adhering the plies together.
Spirally wound tubes are used in a variety of applications in which radially inward compressive forces are imposed on the outside diameter (“OD”) of the tubes. For example, continuous materials such as paper, plastic film, metal sheet, and textiles are commonly wound about winding cores formed of spirally wound paperboard tubes. The winding tension required for winding a stable roll of such materials results in substantial compressive forces being exerted by the wound material on the tube in the radially inward direction. Such forces are in a direction to tend to force the inner diameter (“ID”) of the tube to shrink in size. This phenomenon has been referred to as “ID comedown.”
The degree to which a given paperboard tube resists such inner diameter reduction under a given load is referred to herein as the ID stiffness of the tube. The ID stiffness may be expressed as the amount of radially inward uniform compressive pressure on the tube's OD that the tube can withstand for a given amount of ID reduction; thus, for instance, the ID stiffness may have units of psi per inch of inner diameter reduction.
In web winding applications, it is desirable to have a high ID stiffness so that the tube can readily be removed from a winding apparatus after a roll of web material is wound onto the tube. A winding apparatus typically includes some type of chuck or mandrel that is inserted into the tube and is radially expanded to grip the core from the inside. If the tube inner diameter shrinks too much as a result of the forces imposed by the wound material, it can be difficult or impossible to remove the tube from the winding apparatus without destroying the tube.
It is also desirable to have a high OD stiffness. The OD stiffness of a core is the degree of resistance of the core to growth in outside diameter caused by radially-outward pressure exerted on an inner surface of core, such as by expandable winding chucks or mandrels. Such OD growth can lead to problems, particularly when the chucks or mandrels are retracted and the OD shrinks back toward its original size. This can cause a loss of tension in the inner layers of the wound roll of material, which can lead to loss of roll stability, particularly for slippery materials such as sheet metal. It is desirable in many cases to maximize the OD stiffness of a core.
The assignee of the present application has previously discovered that the core's ID stiffness and/or OD stiffness can be increased by forming the core wall to have a radially central region whose compliance in the radial direction is increased relative to that of the core wall regions lying radially inward and radially outward of the central region. See, for example, U.S. Pat. No. 5,505,395, incorporated herein by reference. In the '395 patent, this increased compliance was achieved by using paperboard plies of lower density and strength in the central region of the wall relative to the density and strength of the plies lying radially inward and outward of the central region. Also see, for example, U.S. Pat. No. 6,851,643, incorporated herein by reference. In the '643 patent, this increased compliance was achieved by intentionally introducing wide ply gaps into one or more plies of the central region.
While the approaches represented by the '395 and '643 patents are effective in enhancing the ID stiffness of tubes, it would be desirable to be able to achieve even greater gains in ID stiffness, and to do so in a cost-effective manner.
The present invention addresses the above concerns and achieves other advantages by providing a spirally wound paperboard tube have enhanced ID stiffness. The paperboard tube includes a spring-like intermediate zone between an outer zone and an inner zone. The intermediate zone includes offset plies and gaps that allow radial deflection of the inner zone toward the outer zone while reducing the deformation of the outer zone, i.e. the intermediate zone absorbs at least some of the deformation rather than the outer zone. Similarly, the intermediate zone also allows radial deflection of the outer zone toward the inner zone while reducing the deformation of the inner zone.
According to one embodiment of the present invention the spirally wound tube includes an inner zone, an outer zone, and an intermediate zone. The inner zone is located radially inwardly and includes one or more inner layers. Each inner layer includes one or more inner plies. The outer zone is located radially outwardly and includes one or more outer layers. Each outer layer includes one or more outer plies. The intermediate zone is located between the outer zone and the inner zone and includes more than one intermediate layer. Each intermediate layer includes one or more one intermediate plies.
In particular, the intermediate zone includes at least a first intermediate layer, a second intermediate layer, and at least one support layer. The first intermediate has one or more first intermediate plies that are spirally wound with first gaps between adjacent edges of the first intermediate plies. The second intermediate layer has one or more second intermediate plies that are spirally wound with second gaps between adjacent edges of the second intermediate plies. The first gaps are radially aligned with the second intermediate plies and the second gaps and the second gaps are radially aligned with the first intermediate plies. And the support layer or layers is between the first and second intermediate layers.
One or more of the support layers may include one intermediate support ply that is wound with substantially no gaps between adjacent edges of the intermediate support ply. Also, according to some embodiments, the intermediate zone includes a plurality of support layers that define a first set of intermediate layers.
The intermediate zone may further include a second and a third set of intermediate layers. For example, a second set of intermediate layers may include the first intermediate layer and at least one additional intermediate layer. The at least one additional layer has one or more intermediate plies that are spirally wound with gaps between adjacent edges of the intermediate plies, and the gaps of the at least one additional layer are radially aligned with the first gaps of the first intermediate layer.
Similarly, the intermediate zone may include a third set of intermediate layers that includes the second intermediate layer and at least one additional intermediate layer. The at least one additional layer has one or more intermediate plies that are radially aligned with the second gaps of the second intermediate layer.
Each ply and gap defines a width. The widths of the plies and gaps may vary relative to each other. For example, the width of each first and second intermediate ply in the first and second intermediate layers may be less than half the width of the intermediate support ply of the at least one support layer. The width of the first and second intermediate plies of the first and second intermediate layers may be less than, equal to, or greater than the first and second gaps of the first and second intermediate layers.
In another aspect, the present invention provides a method of constructing a paperboard tube having an enhanced ID stiffness. The method includes spirally winding one or more inner plies about a forming mandrel to form an inner tube wall zone on the mandrel, spirally winding one or more intermediate plies to form at least a first intermediate layer having gaps between consecutive turns of the one to a plurality of intermediate plies, spirally winding one or more intermediate plies to form at least one support layer, spirally winding one or more intermediate plies to form at least a second intermediate layer opposite the support layer or layers from the first intermediate layer and having gaps between consecutive turns of the one to plurality of intermediate plies, wherein the gaps of the second intermediate layer are radially aligned with the intermediate plies of the first intermediate layer and the gaps of the first intermediate layer are radially aligned with the intermediate plies of the second intermediate layer, and spirally winding from one to a plurality of outer plies for forming an outer tube wall zone.
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 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.
As illustrated in
As used herein, a “layer” is a region of the tube 10 delimited by an outer radius ro 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
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 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.
Each intermediate layer has one or more plies, referred herein as intermediate plies or intermediate support plies due to their location. In contrast to the inner layers 201, 202, 203 and outer layers 401, 402, 403, at least two of the intermediate layers 301, 302, referred to herein for illustrative purposes only as a first intermediate layer 301 and a second intermediate layer 302, are wound such that a gap exists between consecutive turns of a ply or adjacent plies. For example, according to the illustrated embodiment of
In intermediate layers having intentionally created gaps, the intermediate plies may be substantially narrower than the outer and inner plies or the intermediate plies in each intermediate layer free of intentionally created gaps. The substantially narrower intermediate plies are for forming the gaps and may be “mini-plies,” as described in U.S. application Ser. No. 11/225,547.
As shown in
The intermediate zone further includes one or more intermediate support layers radially between the first and second intermediate layers. (Labeling these layers, as well as their respective plies, as “support” is primary to illustrate that the layers are positioned between the first and second intermediate layers and should not be construed as a limitation beyond being positioned between the first and second intermediate layers.). For example and according to the embodiment of
The widths of the plies in the intermediate layers and the intermediate support layers may vary relative to each other or to the gaps. For example, as shown in the illustrated embodiment, the width of each first and second intermediate plies 3011, 3012, 3021, 3022 in each of the first and second intermediate layers 301, 302 may be less than half the width of the intermediate support ply 3031 of the at least one support layer 303. The width of the first and second intermediate plies 3011, 3012, 3021, 3022 of each of the first and second intermediate layers 301, 302 may be less than, equal to, or greater than the first and second gaps 1001, 1002, 1003, 1004 of each of the first and second intermediate layers 301, 302.
In some embodiments, for each intermediate layer 301, 302, the total width of the intermediate plies 3011, 3012, 3021, 3022 and the gaps 1001, 1002, 1003, 1004 may be substantially equal to the width of an intermediate support ply 3031. Therefore, in such embodiments, the widths of the intermediate plies 3011, 3012, 3021, 3022 and width the gaps 1001, 1002, 1003, 1004 may have an inverse relationship, i.e., the greater the widths of the plies, the lesser the widths of the gaps and the lesser the widths of the plies, the greater the widths of the gaps. As examples, the total width of the two intermediate plies per intermediate layer of the illustrated embodiment may equal to be three-fourths, two-thirds, one-half, one-thirds, or one-fourths of the width of the support ply and, thus, the total widths of the two gaps per intermediate layer of the illustrated embodiment may be one-fourths, one-thirds, one-half, two-thirds, or three-fourths respectively of the width of the support ply.
According to another embodiment of the present invention, each of the first and second intermediate layers, as well as the intermediate support layer, may be part of a set of intermediate layers. A set of intermediate layers is a number of intermediate layers radially adjacent to one another. For example, the intermediate zone may have a first set of intermediate layers that includes a third intermediate support layer 303 and at least one additional intermediate support layer. According to the illustrated embodiment of
The intermediate zone 30 may have a second set 102 of intermediate layers in addition to or instead of the first set 101 of intermediate support layers. The second set of the intermediate layers may include the first intermediate layer and at least one additional intermediate layer. According to the illustrated embodiment of
The intermediate zone 30 may have a third set 103 of intermediate layers in addition to or instead of one or both of the first set 101 and second set 102 of intermediate layers. The third set 103 of the intermediate layers may include the second intermediate layer and at least one additional intermediate layer. According to the illustrated embodiment of
One in the art should appreciate that additional sets of intermediate layers and/or additional individual intermediate layers may be added to the present invention beyond what is discussed above or illustrated in the appended figures of the present application.
As further discussed below, the present invention provides increased I.D. stiffness and/or increased O.D. stiffness. It is believed that the intermediate zone functions as a spring or springs between the inner zone and the outer zone. Specifically, the intermediate zone allows radial deflection of the inner zone toward the outer zone while reducing the deformation of the outer zone, i.e. the springs absorb at least some of the deformation rather than the outer zone. Similarly, the intermediate zone also allows radial deflection of the outer zone toward the inner zone while reducing the deformation of the inner zone.
Different core embodiments of the present invention were tested and compared against conventional prior art paper tubes, referred to as a “control solid core.” Listed below are the details of the control solid cores, the tested embodiments, and the comparison of the ID stiffness of the tested embodiments to the control solid cores. One in the art should appreciate that the tested embodiments are for testing and illustrative purposes only and do not represent any limitations to the present invention.
During a first group of testing, a first control solid core (referred to below as “1st Control Solid Core”) was compared to five different embodiments of the present invention (referred to below as 1st through 5th Tested Embodiments). Each core generally had the same inner and outer zones. Specifically each inner zone had four inner layers, each inner layer included one inner ply and each inner ply had a density of 0.661 g/cm̂3 and a relative low strength. The innermost layer had a caliper thickness of 0.025″ and each of the remaining three inner layers had a caliper thickness of 0.030″. Each outer zone had four outer layers. The outermost layer had one outer ply that had a caliper thickness of 0.013″, a density of 0.759 g/cm̂3 and relative low-medium strength. The second outermost layer had one outer ply that had a caliper thickness of 0.025″, a density of 0.661 g/cm̂3, and relative low strength. Each of the two remaining outer layers had a caliper thickness of 0.030″, a density of 0.661 g/cm̂3, and relative low strength.
The differences between the control solid cores and the different tested embodiments were generally in the number and structure of the intermediate layers of the intermediate zone in the respective core or embodiments. Specifically, the intermediate zone of the control solid core and the tested embodiments of the present invention were the following:
Four intermediate layers, wherein each layer includes one intermediate ply having a caliper thickness of 0.025″, a density of 0.661 g/cm̂3, and relative low strength.
A first intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength;
Two intermediate support layers, wherein each layer includes one intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength; and
A second intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength.
A first intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength;
Two intermediate support layers, wherein each layer includes one intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength; and
A second intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength.
A first intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength;
Two intermediate support layers, wherein each layer includes one intermediate ply a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength; and
A second intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength.
A first intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength;
Two intermediate support layers, wherein each layer includes one intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength; and
A second intermediate layer having two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength.
A first and a fifth intermediate layer, wherein each layer includes two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength;
Two intermediate support layers, wherein each layer includes one intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength; and
A second and a sixth intermediate layer, wherein each layer includes two intermediate plies and gaps between adjacent edges of the two intermediate plies, each intermediate ply having a caliper thickness of 0.025″, a density of 0.711 g/cm̂3, and relative medium strength.
The following table illustrates the improvement to the ID stiffness of the tested embodiments compared to the 1st Control Solid Core:
During a second group of testing, a second control solid core (referred to below as “2nd Control Solid Core”) was compared to one embodiment of the present invention (referred to below as the 6th Tested Embodiment). The 2nd Control Solid Core had the following layer structure:
an inner zone having one inner layer, the inner layer having one inner ply, the inner ply having a caliper thickness of 0.020″, a density of 0.711 g/cm̂3 and relative medium-high strength;
an intermediate zone having seven intermediate layers, each intermediate layer having one intermediate ply, each intermediate ply having a caliper thickness of 0.022″, a density of 0.759 g/cm̂3, and a relative high strength;
an outer zone having a first outer layer radially adjacent to the intermediate zone, the first outer layer having one outer ply that has a caliper thickness of 0.022″, a density of 0.759 g/cm̂3, and a relative high strength, and a second outer layer having one outer ply that has a caliper thickness of 0.013″, a density of 0.759 g/cm̂3 and relative low-medium strength.
The sixth tested embodiment had the following layer structure:
an inner zone having two inner layers, each inner having one inner ply, the innermost layer having a caliper thickness of 0.020″ a density of 0.711 g/cm̂3 and medium-high strength and the other inner layer having a caliper thickness of 0.022″, a density of 0.759 g/cm̂3 and relative high strength;
an intermediate zone having a first set of two intermediate layers, each layer of the first set has one ply with a caliper thickness of 0.025″, a density of 0.661 g/cm̂3 and relative low-medium strength and one gap, the layers of the first set of intermediate layers are radially align such that the ply of one layer radially aligns with the ply of the other layer and the gap of one layer radially aligns with the gap of the other layer; a set of support layers extending radially outward from the first set of two intermediate layers, the set of support layers includes two support layers, each support layer includes one support ply having a caliper thickness of 0.022″, a density of 0.759 g/cm̂3 and relative high strength; and a second set of two intermediate layers radially opposite of the set of support layers from the first set of two intermediate layers, each layer of the second set has one ply with a caliper thickness of 0.025″, a density of 0.661 g/cm̂3 and relative low-medium strength and one gap, the layers of the second set of intermediate layers are radially align such that the ply of one layer radially aligns with the ply of the other layer and the gap of one layer radially aligns with the gap of the other layer, and wherein the layers of the second set of two intermediate layers is radially offset from the layers of the first set of two intermediate layers such that the gaps of one set radially aligns with the plies of the other set; and
an outer zone having two outer layers radially adjacent to the intermediate zone, wherein each of the two outer layers has one outer ply having a caliper thickness of 0.022″, a density of 0.759 g/cm̂3 and relative high strength, the outer zone further having a second outermost layer having one outer ply with a caliper thickness of 0.022″, a density of 0.759 g/cm̂3, and relative high strength, and an outermost layer having one outer ply with a caliper thickness of 0.022″, a density of 0.759 g/cm̂3 and relative low-medium strength.
The following table illustrates the improvement to the ID stiffness of the 6th tested embodiment compared to the 2nd Control Solid Core:
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 50, adhering the plies together, and severing portions or sections of the spirally wound plies to form individual tubes 10.
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.
