Patent Publication Number: US-2004050988-A1

Title: Method and apparatus for packing material under compression and the package made thereby

Description:
RELATED APPLICATIONS  
     [0001] This application claims priority to U.S. Provisional application No. 60/438,293 filed Jan. 7, 2003, U.S. Provisional application No. 60/420,331 filed Oct. 23, 2002, and U.S. Provisional application No. 60/409,988 filed Sep. 12, 2002. The entire contents of each of these applications is hereby incorporated by reference herein. 
    
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002] [Not Applicable] 
       REFERENCE TO A SEQUENCE LISTING  
       [0003] [Not Applicable] 
       BACKGROUND OF THE INVENTION  
       [0004] 1. Field of the Invention  
       [0005] This invention relates to handling material, especially packaging sheet or strip material. More particularly, this invention relates to forming packages of wound sheet or strip material under compression.  
       [0006] 2. Description of Related Art  
       [0007] The material handling industry is focused on handling different types of materials efficiently, at the lowest possible cost while maintaining material integrity. Handling batting has a long history and has evolved as batting materials have changed. Before the advent of synthetic materials, batting consisted of cotton or wool fiber wadded into rolls or sheets. These sheets were called wadding, which is a soft layer of fibrous cotton or wool, used for padding or stuffing. Such stuffing was used for a variety of items, ranging from furniture, mattresses, bedding, or even feminine hygiene products and other medical items that required absorbent material.  
       [0008] A common way traditional wadding was handled included compressing the wadding and rolling it into a roll. This technique was based on the method of making cotton bales. For example, U.S. Pat. No. 546,009 to Graves discloses a method of forming a cylindrical cotton bale in which cotton flakes are blown from a chute of a cotton gin onto a condensing cylinder to form a bat. The bat is compressed by rollers and passed down a guide to a compression roller. The tightly compressed bat is passed to guide rollers and between a belt and spindle. The belt causes the bat to be spirally wound on the spindle thereby applying pressure to each layer in the bale.  
       [0009] As the materials became more sophisticated, the method of handling the material evolved. For example, U.S. Pat. No. 2,353,821 to Fourness et al. describes the method of making a compressed wadding roll using, in one example, “white” wadding used largely in the manufacture of sanitary pads. As noted in Fourness, such “white” wadding is lively and must re-expand before its conversion to sanitary pads, which require a very uniform product. The apparatus of Fourness was designed as an adjunct to a wadding compressor in which compressed wadding is fed to the device to wind the compressed product into a roll ready for storage and shipment. The winding apparatus includes upper and lower transfer plates that transfer the compressed wadding to the throat of the winder where it is caught in the nip of the winder belt and core. Fourness&#39; device packaged compressed wadding in lengths of nine feet or more so that short pads for individual sanitary napkins could be cut from the roll.  
       [0010] While methods to handle wadding made of cotton or wool were developed so that rolls were made that were easier to transport and handle, the material itself had its limitations. Severe compression of cotton wadding caused the material to become “planky” or stiff. Textile wadding was not well suited for single use applications as it is expensive. It was also bulky and costly to handle and transport.  
       [0011] In response to these problems, nonwoven fibrous materials suitable for household and industrial use were developed in the 1960&#39;s and 1970&#39;s. By the mid to late 1970&#39;s, nonwoven fibrous materials had developed to the point at which they became accepted as replacements for conventional textile fabrics. Such nonwoven sheets possess properties similar to conventional textiles in terms of strength, bulk, flexibility and softness, but are less expensive and especially suited for single and limited use applications. Nonwovens became commonplace for use as household and industrial wipers and for components in sanitary napkins and disposable diapers. Now, nonwovens have gained wide acceptance and are in common use as protective garments, including sanitary napkins and diapers, wipers, health care items, including bed linens and surgical drapes, filtration media, and automotive items, for example. Nonwovens can also be used in garments, such as jackets and raingear, and linens, such as draperies, comforters, and mattress covers.  
       [0012] Manufacturing nonwoven materials is very different than making bales of cotton in which cotton flakes are blown onto a compressor or cotton or wool fibers are matted together into bats. Thus, new techniques were created to form these nonwoven materials. At the initial phases of nonwoven development, a technique was proposed that included forming a fabric scrim with fibers attached thereto, as disclosed in U.S. Pat. No. 2,900,980 to Harwood. Although this product had a soft feel, it was expensive as the majority of the material was formed by textile length fibers, rather than the less expensive short cellulosic fibers. Therefore, new processes were developed to use the short inexpensive cellulosic fibers to create a web of material. The techniques developed in the 1970&#39;s for making nonwovens focused on using short cellulosic fibers that were delicately entangled and created a product that had different inherent characteristics than traditional textile fabrics.  
       [0013] One technique employed an air-laid web that blends randomly arranged and intermingled short cellulosic fibers and longer reinforcing fibers permanently bonded together with a binder, which then sets to form a finished web having a predetermined density and loft. See, for example, U.S. Pat. No. 4,127,637 to Pietreniak et al.  
       [0014] Another air laid technique, disclosed in U.S. Pat. No. 4,100,324 to Anderson et al., mechanically entangled fibers by merging a primary air stream of melt blown microfibers and a secondary air stream of wood pulp fibers under turbulent conditions.  
       [0015] An ultrasonic technique described in U.S. Pat. No. 4,109,353 to Mitchell et al. passed fibrous webs through a vibrating nip in the presence of uncombined liquid. Movement of the liquid within the web causes rearrangement and entanglement of the fibers resulting in a web that has desirable strength, drape and softness.  
       [0016] A chemical technique extruded a thermoplastic polymer into filaments with a lubricating agent, collected the extruded filaments in a web, and applied heat. See, for example, U.S. Pat. No. 4,070,218 to Weber.  
       [0017] These techniques were developed to enhance material properties, such as porosity and absorbency, that are highly desirable in nonwoven sheets. To provide sufficient absorbency, it is important to have internal channels for fluid flow through the material. Softness and aesthetic appearance are also important properties so that the nonwovens can approximate conventional textile fabrics and not be stiff and paper-like.  
       [0018] As discussed in U.S. Pat. No. 3,978,257 to Ring, it was discovered in the 1970&#39;s that the conventional papermaking processes used for producing fibrous materials that used water for laying fiber and creating interfiber hydrogen bonds formed materials that were stiff, harsh and had low absorbency. Thus, subsequent processing steps were required, such as creping, to soften the material and increase its absorbency and bulk by breaking some of the interfiber bonds and opening the surface and internal structure.  
       [0019] On the other hand, air laying processes generally employed adhesive for interfiber bonding. Adhesive content was increased to increase strength, and the material was compressed to insure that the short fibers were bonded. This also resulted in increased stiffness and the reduction of the size and frequency of fluid retaining spaces between the fibers, thus reducing absorbency. So, it became common to enhance softness of a fibrous web by creping and controlled compaction to work the fibers. Nonwoven webs were also embossed using special techniques to improve strength. Another process used to increase the absorbent rate was to brush the layers of material to remove loose fibers and open the internal pore structure.  
       [0020] Thus, handling and processing nonwoven materials is far more complex than conventional textile fabrics. The types of fibers vary, and many nonwovens use a combination of different types of fibers, such as a synthetic fiber and natural fiber mix. Also, the entanglement of the fibers is significant. It is important to obtain the optimum entanglement for strength while trying to minimize stiffness and enhance absorbency. If the material is handled too roughly prior to the end manufacture, the delicately entangled fibers will become damaged and the properties will change.  
       [0021] The following physical properties of nonwovens are often measured to assess the material&#39;s suitability for certain applications. Uncompressed thickness is measured using an approved thickness tester. Bulk density is calculated using the measured uncompressed thickness and sample basis weight. Oil and water absorbency is tested by placing a previously weighed sample of material in a bath and then removing and draining the material. The drained material is then weighed again and the differential is divided by the density of the liquid and then by the dry weight of the material sample to obtain an absorbency level. Dry and wet breaking length is calculated by measuring tensile strength of a dry or wet material sample that is divided by the basis weight of the sample. Stretch can be determined by using the increasing length measured during the tensile strength test and percentage increase in length of the sample just prior to breaking. Lint count is obtained by bending, twisting and crushing a sample over a filter and then measuring the particles trapped by the filter. Specific volume is determined by dividing the uncompressed thickness by the basis weight of the sample to determine the initial specific volume. The sample is then compressed to a certain value and the compressed thickness is measured and divided by the basis weight to determine the loaded specific volume. The recovered specific volume is determined by measuring the recovered thickness of the sample after the load is removed divided by the basis weight.  
       [0022] The properties of nonwoven materials are monitored closely by nonwoven manufacturers to ensure that the material is consistent and meets the requirements of an end user, such as a diaper or sanitary napkin manufacturer. These considerations also apply to nonwoven materials that are made of foam, for example, rather than interlocked fibers.  
       [0023] After forming the nonwoven web, the material is rolled onto a master roll, which can then be transported for use or split into smaller sheets or strips used to make smaller rolls of material. These rolls are spiral wound into what is commonly called a pancake roll, represented in FIG. 2. It is important that the initial characteristics of the material obtained upon its manufacture be maintained during subsequent processing and transport. For instance, nonwoven material intended to be manufactured into to diapers must be handled in a way such that it arrives at the diaper manufacturer with its initial manufactured characteristics, especially as to product performance.  
       [0024] Conventional methods of handling wadding discussed above manipulate the material to compress it to make a more compact package that is easier to handle and less expensive to transport and store. These techniques are still used for packaging such things as insulation formed of felts of mineral fibers, as disclosed in U.S. Pat. No. 5,305,963 to Harvey, III et al. and U.S. Pat. No. 5,425,512 to Bichot et al., for example. However, such compression techniques using nips and compression plates that are suitable for fibrous materials in which material integrity is not critical cannot be used with modern nonwovens as the internal structure of the nonwoven material is damaged using conventional compression techniques.  
       [0025] Compression using a nip or plate, as used in compressing insulation, applies a large pressure in a small area of the sheet. Such an application of pressure in a concentrated area tends to damage nonwovens by breaking fibers. This is illustrated in FIG. 3 in which a compressible sheet  210  is pressed by a compression belt  220  at a compression point P, which breaks fibers at that point. FIG. 4 shows a compressible sheet  230  pressed by nips  240  at a compression point P, which also breaks fibers at that point. Damage to the nonwoven structure can adversely affect its rebound, strength, stretch and absorbency, among other qualities. In particular, if the delicately entangled fibers are broken or the cells of a foam are crushed, the fluid path is compromised.  
       [0026] Thus, to avoid damaging the material, nonwovens are presently wound on rolls with no significant compression, which results is large rolls that are difficult to handle and expensive to transport and store. FIG. 2 shows a conventional pancake roll  200  wound with no compression. Section B of FIG. 2 shows the fibers of the nonwoven being in their original entangled state. Even winding without compression can create problems in spiral wound rolls in which the inner layers can be unevenly pressed by the outer layers.  
       [0027] Additionally, winding compressible material under tension to obtain a larger run of material on each roll is not effective. Placing nonwoven compressible material under tension can also damage the internal fibers by breaking them and thus cause performance of the material to degrade.  
       [0028] Other methods to obtain a compressed roll to reduce its volume for storage and transportation have also been problematic. For example, compressing the wound package after forming the roll causes the roll to have a reduced diameter, which in turn reduces the circumference of the each wound layer. This forces the layers inwardly toward the core and creates creases or folds in the layers in order to reduce the circumference. A result is inconsistent compressing and potential damage to the material.  
       [0029] There is a need, therefore, for a method and apparatus that can efficiently package nonwoven material while maintaining its manufactured characteristics. It would be desirable to form a compressed package of nonwoven material in which air is removed from the wound layers while the material experiences no damage.  
       SUMMARY OF THE INVENTION  
       [0030] An aspect of this invention provides a significantly compacted roll of nonwoven material that has material characteristics suitable for an end use manufacturer.  
       [0031] Another aspect of this invention provides a package that is less expensive to transport and store due to its compacted size.  
       [0032] An additional aspect of this invention provides a method of winding an uncompressed nonwoven sheet of material into a roll under compression controlled to significantly reduce the thickness of the sheet with no damage to the material. The method also includes forming plural compressed rolls on a single core.  
       [0033] A further aspect of this invention provides an apparatus for compression winding a package in conjunction with a traverse winding assembly.  
       [0034] Another aspect of the invention provides a package formed of a compressed traverse wound roll or a plurality of pancake rolls on a single core.  
       [0035] An additional aspect of the invention provides a method of controlling compression of a package of nonwoven compressible material based on the inherent characteristics of the material to maximize compression and minimize material damage.  
       [0036] A further aspect of the invention is to provide a package in which the material is under substantially uniform pressure throughout. The compressed material is not under tension. The apparatus for making the package can have a controller that balances compression with the material properties. The method of making such a package includes the step of controlling the compression on each layer of the package.  
       [0037] The invention provides a package comprising a core having a length and strip material having a width less than the length of the core wound in a traverse pattern over substantially the length of the core under compression, wherein the strip material is under substantially uniform pressure throughout the entire package. The material may be nonwoven and may be continuous.  
       [0038] The invention also provides a package comprising a core having a length and strip material wound on the core under compression in a pattern of a plurality of stacked rolls with stepped interconnected strip portions between each roll on the core, wherein the strip material is under uniform pressure throughout the entire package. The strip material may be nonwoven and material and may be continuous.  
       [0039] The invention further provides a package comprising a core having a length and strip material wound on the core substantially across its length, wherein the strip material has a thickness, is nonwoven, has substantially no tension, and is compressed to substantially reduce the thickness. The pressure on each layer is substantially uniform throughout the entire package.  
       [0040] The invention additionally provides a method of forming a package wherein strip material is formed into a roll supported by a core, comprising feeding an uncompressed strip of material to the core and winding the strip onto the core with a driven belt that substantially surrounds the core to wrap the strip around the core with the strip under compression. The strip may be wound on a single core, plural strips may be wound on a single core, or plural strips may be wound on plural cores.  
       [0041] The invention also provides a method of forming a package, comprising feeding a sheet of material to a packaging apparatus having at least one core and at least one driven belt that substantially surrounds the core, separating the sheet into a plurality of strips, driving the belt under tension, and winding each strip onto a core with the belt thereby compressing the strip and forming a package under uniform pressure throughout. The sheet may be uncompressed or precompressed when fed to the apparatus.  
       [0042] The invention provides an apparatus for forming a package of strip material wound on a core under compression, comprising a winding device having a frame, a longitudinal core support mounted to the frame, and a driven belt supported by the frame to substantially surround the core and a strip material feeding apparatus disposed adjacent to the winding device and including a traverse feeder that moves the strip material longitudinally with respect to the core. The driven belt is controlled to wind the strip material onto the core under compression. The apparatus can include a material separator that separates the strip material from a sheet of material.  
       [0043] The invention further provides an apparatus for forming a package of strip material wound on a core under compression, comprising a winding device comprising a frame, a longitudinal core supported by the frame, and a driven belt supported by the frame to substantially surround the core and strip material feeding apparatus including a material separator that separates strips from a sheet of material, wherein the separated strip is wound onto the core by the driven belt.  
       [0044] The invention additionally provides an apparatus for forming a package of strip material wound on a core under compression, comprising a frame, a longitudinal core supported by the frame, a driven belt supported by the frame to substantially surround the core, and a controller coupled to the driven belt that adjusts tension of the belt based on parameters of the strip material so that fibers in the compressed strip material do not break.  
       [0045] These and other aspects of the invention will become apparent from the description herein taken in conjunction with the drawing figures. 
     
    
    
     DESCRIPTION OF THE DRAWINGS  
     [0046] Referring to the drawings that form part of this original disclosure:  
     [0047]FIG. 1 is a side view of a package formed in accordance with this invention, with an enlarged cut out portion A;  
     [0048]FIG. 2 is a side view of a prior art package, with an enlarged cut out portion B;  
     [0049]FIG. 3 is prior art compressing apparatus;  
     [0050]FIG. 4 is another prior art compressing apparatus;  
     [0051]FIG. 5 is a partial side perspective view of a package being formed in accordance with an embodiment of the invention;  
     [0052]FIG. 6 is a partial side perspective view of a package being formed in accordance with another embodiment of the invention;  
     [0053]FIG. 7 is a side schematic view of an apparatus in accordance with the invention in a winding position;  
     [0054]FIG. 8 is a side schematic view of an apparatus of FIG. 7 in a discharging position;  
     [0055]FIG. 9 is a top schematic view of an apparatus arrangement in accordance with an embodiment of the invention;  
     [0056]FIG. 10 is a top schematic view of another apparatus arrangement in accordance with the invention;  
     [0057]FIG. 11 is a top schematic view of an additional apparatus arrangement in accordance with the invention; and  
     [0058]FIG. 12 is a side view of a precompression apparatus in accordance with an aspect of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0059] The invention is described with reference to a package. It is to be understood that this description of a package is intended to cover various sizes of packages, ranging from large mill rolls to small rolls suitable for light industrial applications. It should also be understood that the material is described referring to a sheet or strip that is intended to include various configurations of materials generally formed in a mat, tape, web or elongate form. The strips can range from very narrow, for example several inches or about 10 mm, to very wide, for example about ten feet or two meters.  
     [0060] For purposes of illustration, the particular type of material described herein is nonwoven materials, which can be similar to those described in the background section of this document. The nonwoven material referred to herein includes various materials formed of interconnected fibers that are not woven like a conventional textile. The materials tend to carry relatively large amounts of air between the interstices of the material fibers or elements. The nonwovens can include material that is fibrous, air laid, and/or compressible. The types of material include filtration media, cellulosic, polyester, polymeric, glass, spun bond, open cell foam, and composites that could include films. However, such description should not be deemed to limit the inventive concepts disclosed herein strictly to nonwoven materials. It is envisioned that the compression and packaging techniques could be used on various types of materials including films, foils, plastics, mechanical fastening tape, drawstrings, elastomerics, foams, and even textiles if desired.  
     [0061] A package  10  formed in accordance with this invention is shown in FIG. 1. The package  10  includes a core  12  with a strip of material  14  wound around the core  12  under compression, as will be discussed below. As seen by comparison to FIG. 2 in which a conventional package with no compression is formed, package  10  holds a significantly longer strip of material  14  than a conventional package  200 . The strip  14  may be continuous, that is the strip  14  may be formed of a series of interconnected strips to form a continuous strip, which is more desirable in an end use manufacturing assembly so that frequent stopping for strip replenishment is not necessary. Various known ways of forming a continuous strip, including splicing, may be used.  
     [0062] The section A of FIG. 1 shows that the strip  14  is layered with uniform compression. The fibers  16  are more compactly arranged due to the removal of air from between the fibers  16 . The compression is not so great, however, that the fibers  16  are broken or the properties of the strip  14  are changed. Various degrees of compression can be obtained depending on the particular material used. In this case, compression of about 6 to 1 is achieved. It will be appreciated that this offers significant savings in terms of storage and transportation and manufacturing efficiency due to a reduction in change over and down time.  
     [0063] It has been discovered by this inventor that nonwoven materials may be compressed using a uniform pressure that consistently surrounds the material  14  as it is being wound on the core  12  to a certain degree without experiencing deleterious effects on the properties of the nonwoven material. By gently removing the air from between the fibers  16  and applying a uniform pressure around the core  12 , the material  14  reduces thickness without breaking the fibers  16 . This a much more complex process than merely baling a strip of material by simply rolling the material within an enclosure to wrap subsequent layers around inner layers. This is also a significant change from pressure point compression, as illustrated in FIGS. 3 and 4, that applies a small area of high pressure that broke fibers and compromised the quality of the material.  
     [0064] As will be appreciated from this disclosure, the tension in the wound strip is reduced to a minimum value that is necessary to just carry the material  14  to the compression area between the package  10  and the guide roll, described below. As the winding progresses, it is desirable that the material  14  remains at a constant tension and compression throughout the length of the material  14  within the package  10 .  
     [0065] Upon use, the material  14  from packages  10  formed in accordance with this invention exhibit no harmful effects from the compression. Further, when opened, the packages  10  gently expand or rebound without exhibiting a popping or springing effect that is difficult to manage in a manufacturing environment. This is a result of compressing the material  14  without tensioning the strips so the potential energy in the strips  14  causes the fibers  16  to expand with respect to each other allowing air into the interstices, and not rebound from tension in the strips  14 .  
     [0066] The basic concept of winding the material  14  while compressing is shown in FIGS. 5 and 6. The embodiment seen in FIG. 5 uses a belt  18  that extends substantially the entire length of the core  12 . The strip of material  14  is fed between a pair of rolls  20  and  22  onto the core  12 . The belt  18  is driven and wraps the strip of material  14  around the core  12  by friction. It should be understood that the strip of material can be any width, and although shown as a thin strip it could extend the length of the core.  
     [0067] Preferably, the belt  18  is formed as an endless sheet of material that has a high tensile strength. An example of a suitable material is a woven urethane bottom that functions as the drive surface and a urethane top surface that is “sticky” or has a high coefficient of friction that contacts the strip of material. A preferred material for belt  18  is impervious PVC. It is also possible to use a belt that is formed as a screen, is semi-permeable or is perforated to allow visual inspection of the package  10  during formation. Of course, any other suitable material may be used for the belt  18 . It is also contemplated that the belt  18  can be formed as plural belts, each forming a segment of a belt system that forms a full circle around the core  12 .  
     [0068]FIG. 6 shows an alternate belt arrangement in which a narrow belt  24  that is approximately the width of the strip  14  is used. In this case, the belt  24  still fully surrounds the strip  14  as it is fed between rolls  26  and  28  to be wound on the core  12 .  
     [0069] It will be appreciated that in this arrangement, it is possible to accurately control both the tension in the belt  18 ,  24  and the pressure between the package  10  and the rolls  20  and  22 ,  26  and  28  where the compression occurs. By this, all of the required compression in the material  14  from its normal or at rest thickness down to the desired compressed thickness occurs in the area between the package  10  and the rolls  20  and  22 ,  26  and  28  between which the material  14  passes. At this point the air is expelled from the interstices of the material  14  allowing it to compress to the desired thickness. The belt  18 ,  24  exerts a continuous force against the package  10  throughout rotation of the package  10  from the point at which the material  14  is applied through 360° of rotation until the next layer is applied over the underlying layer.  
     [0070]FIGS. 7 and 8 show a winding apparatus  40  in accordance with one embodiment of the invention. The winding apparatus  40  includes a frame  42  supported on a surface and a core support  44  that supports the core  12  of the package  10 . The core support  44  can take various forms including an elongated spindle or a pair of axles, for example. The core support  44  is carried on a discharge rail  45 . The frame  42  supports a belt support system, in this case rolls, that support and drive the belt  18 . A belt tensioning device  46  is also provided.  
     [0071] The belt  18  support system is formed by a series of rolls, which could also be pulleys, including rolls  48  and  50  at the base of the frame  42 , rolls  52  and  54  at the top of the frame  42 , feeder rolls  56 ,  58 ,  60 , and  62  and tensioning roll  64 . Rolls  56  and  58  are carried on a pivoting upper arm  66 , and rolls  60  and  62  are carried on a pivoting lower arm  68  connected at pivot joint  70 . Arms  66  and  68  are controlled by pistons  72  and  74  that are mounted to a support rail  78 . One or more of the rolls are driven so as to turn the endless belt  18  around the path of rolls. In this case, for example, roll  50  is driven. However, another roll in the assembly could function as the driving roll.  
     [0072] Belt tensioning device  46  also consists of a series of rolls, or pulleys, mounted on a driven rod  80 . Rod  80  can be any driven device, but in this case is a pneumatic piston with a pulley  82  on one end. Rolls  84 ,  86 , and  88  are mounted on the frame  42  and form a path for a tensioning strap  90 . The strap  90  extends from tensioning roll  64  around rolls  88 ,  86 , and  84  to pulley  82  and is then mounted to roll  52  or any other fixed point on the frame  42 . The tensioning device  46  may be manually controlled or may be connected to a controller C that is programmed to control driven device  80  to tension and release the belt  18 , as discussed below.  
     [0073] Preferably, the core  12  is supported so that it can move naturally in response to the increasing diameter of the package  10 . However, if desired, the controller C can control the position of the core  12  to affect the tension in the belt  18  and, thus, the pressure on the package  10 . The controller C detects the core  12  speed and then determines the belt  18  tension. The position of the core  12  can be then moved to counterbalance the tension in the belt  18 . This control is especially useful if the material  14  is buckling between the rolls  58  and  60 . The core  12  position can also be controlled to assist in removal of the package  10 , as discussed below.  
     [0074] An anti-static device can be provided on the winding apparatus  40  to dissipate static charges generated during winding by the belt  18 . FIG. 7 shows a metal screen  92 , preferably covered by a shield such as Plexiglas, disposed on one side of the apparatus  40  that dissipates static charge from the belt  18  by gathering charge as the belt  18  passes by the screen  92 . Of course, any anti-static arrangement can be employed with the a similar effect.  
     [0075] If desired, an edge guide  94  can also be provided to monitor the position of the edge of the belt  18  and control wandering. As the belt  18  rotates at high speeds, it can have a tendency to wander to one side or the other. Such wandering adversely affects the tension in the belt  18  and compromises the uniform pressure and growth of the package  10 . An example of a suitable edge guide is an optical position detector. A commercially available system suitable for use with the apparatus  40  is an Fife edge guide system, which is a commercially available dynamic guide that repositions the center line of the belt  18  by twisting the belt  18  by adjusting the position of one or more of the rolls.  
     [0076] In operation, the belt  18  extends around rolls  48 ,  64 ,  50 ,  52 ,  54 ,  56 , and  58  and then around core  12  of package  10  and out to rolls  60 ,  62 , and back to roll  48  in an endless loop. As roll  50  is driven, the belt  18  receives an end of the strip  14  between rolls  58  and  60  and catches the strip  14  between the belt  18  and the core  12 . As the belt  18  is driven around the apparatus, the strip  14  is wound around the core  12 . As the package  10  diameter increases, the belt  18  expands around the material  14  to exert an even compressive force on the package  10 . The expansion is accommodated by the belt tensioning device  46 .  
     [0077] The belt tensioning device  46  operates as follows. The tension in the belt  18  is varied based on the position of roll  64 . Roll  64  rides on support rail  78 . The position of roll  64  is determined by the tensioning strap  90 , which travels from roll  64  around rolls  88 ,  86 , and  84  to pulley  82 . Pulley  82  is moved by driven rod  80 . FIG. 7 shows the fully retracted position of rod  80  in which the roll  64  is at its lowermost position and the package  10  is fully formed. To shorten the belt  18  around the package, the roll  64  is pulled upward on rail  78  by extending rod  80  and lowering pulley  82 .  
     [0078] Ideally, the length of the strip  14  is not changed after it is applied to the package  10  by allowing the diameter to expand, thus potentially damaging the material by inducing tension in the material of the strip  14 . Thus, the tension in the belt  18  is maintained to match the expansion forces generated at all points throughout the package  10 . It is apparent that the tension in the belt  18  will increase as the diameter of the package  10  increases. So, the tension in the belt  18  will, in theory, increase in direct proportion to the diameter to maintain a constant pressure on the surface of the package  10 . However, in reality, the pressure must vary to accommodate the changing expansion forces generated by the package  10 , especially as the expansion forces change based on the amount of material  14  supported on the core  12  and the inherent spring force generated by the material  14 .  
     [0079] The tension in the belt  18  must be properly controlled in view of these factors to resist the tendency of the strips  14  to increase or decrease in length as the diameter of the package  10  at that particular layer tends to increase or decrease due to subtle differences in expansion or collapse of the package. If the belt  18  is improperly tensioned, the package  10  will tend to expand or collapse thus causing the strips  14  to increase or decrease in length, which could damage the material, especially since there is high friction between the layers of a nonwoven that entrap air and resist slipping.  
     [0080] It is also desirable to maintain a constant strip  14  thickness while building the package  10 . The layers of strips  14  will tend to expand or contract to maintain a constant thickness between the layers as the forces will be distributed between the layers thus averaging out the compressive forces and the actual amount of compression.  
     [0081] To release the package  10 , roll  64  is pulled by tensioning strap  90  to its uppermost position, as seen in FIG. 8. This shortens the belt  18  to its minimum extent and pushes arms  66  and  68  to pivot about joint  70 , thereby compressing pistons  72  and  74 . Package  10  is then permitted to travel outward on discharge rail  45  for removal from the apparatus. When the belt  18  is slackened, the pistons  72  and  74  urge the arms  66  and  68  into the closed position.  
     [0082] It is preferred that the rolls  58  and  60  be disposed close together to avoid the material  14  from bulging outward between rolls  58  and  60 . However, depending on the degree of desired compression, it is not necessary that rolls  58  and  60  be disposed close together. The degree of compression is determined by using parameters of the material  14  being wound. Based on prior testing of the material to determine the point at which the fibers  16  break down or other characteristics of the material change, the belt  18  is tensioned to impart the maximum pressure the package  10  can withstand without damaging the material  14 , particularly the fibers  16 . By this, the most efficient size package  10  can be produced. As consistent pressure is applied by the belt  18 , compression is substantially uniform throughout each layer of material  14 .  
     [0083] It should be understood that various modifications can be made to this apparatus, including using a narrow belt  24  and using a different tensioning device, if desired. It is possible to feed the material at any position also. Although FIG. 7 shows material being fed from the side, it is also possible to feed the material from below or above.  
     [0084] The material supply used to supply the strip  14  to the apparatus  40  can vary.  
     [0085] FIGS.  9 - 11  show three possible arrangements. It is also possible to supply material directly from the point of manufacture, in other words to use the apparatus  40  to initially package the material on a master roll.  
     [0086] Referring to FIG. 9, the material supply includes a wound sheet of material  100  supported on a supply support  102 . The supply support  102  includes a supply driver  104  that drives the material supply  100  and controls the tension of the strip  14 . It is preferred to supply the strip  14  with minimal tension, ideally no significant tension. The ideal tension will supply the material  14  without creating slack or becoming taut. For example, a preferred negligible tension would be one ounce per inch. Any type of supply support  102  can be provided as long as a stable support is present. The supply driver  104  can also take any form, such as a driven roll. It is not necessary to provide a supply driver  104 , but its presence assists in smoothly supplying the material  14  with negligible tension.  
     [0087] The material supply may also include a separator  106 , which may be any device that divides the sheet of material  100  into strips. One such device is a slitter. Alternatively, as seen in FIG. 11, the material supply  100  may already be separated into strips.  
     [0088]FIG. 9 shows an arrangement in which each strip  14  is fed to an individual winding apparatus  40 . By this, a plurality of packages  10  can be made simultaneously. FIG. 10 shows an arrangement in which each strip  14  is fed to a single core  12 . By this, a plurality of rolls  10  can be formed as a single package  110 . In this case, a single belt  18  or multiple belts can be used.  
     [0089]FIG. 11 shows an arrangement in which a single strip  14  is fed for traverse winding across the length of a single core  12  to form a roll or spool  120 . To accomplish traverse winding, one of the supply  100  or the core  12  is moved so that the strip  14  is wound across substantially the entire length of the core  12 . This enables a large amount of material to be carried on a single core. FIG. 11 shows the core of package  120  moving, however, it is also possible to move the supply  100  or to have a traverse feeder that moves the strip  14 . Such traverse winding is also possible with the arrangements in FIGS. 9 and 10. In addition to traverse winding, it is possible to use step winding in which individual spiral wound rolls are wound on a core interconnected with strips. The winding in this case is accomplished in a stepped fashion so that the rolls are wound in sequence across the core, building each stack gradually. This technique is described in U.S. Pat. No. Re. 32,608, which is incorporated herein by reference.  
     [0090] While in the embodiment described above, the material  14  is not precompressed, it may be desirable in certain situations to precompress the strip  14 . In that case, the precompression would be effected with a gentle or gradual compression so as not to damage the material, as occurred in the prior art. For example, it is possible to employ a series of nips progressively spaced closer and closer together to achieve a gentle precompression prior to feeding the material to the belt compressing device. It is also possible to compress the material with a belt carried on a drum.  
     [0091] A preferred way of precompression, if desired, is by vacuum, which also acts as a feeding control mechanism both holding the material in place and subjecting a compressive force that draws the air out of the material before it enters the apparatus  40 . FIG. 12 shows a vacuum precompression system  130  including a frame  132  that supports a carriage  134  on a rail  136  and a driving mechanism  138 , in this case a driven threaded rod. The carriage  134  slides transversely with respect to the frame  132  and the winding apparatus  40  to feed the strip  14  either traversely to form a spiral wound package or in a stepped fashion to form plural pancake stacks. The carriage  134  supports a driven belt  140  that extends between a plurality of rolls  142 , at least one of which is preferably driven to provide an even supply speed to the material and avoid tensioning or bunching the material as it is being fed to the winding apparatus  40 . A vacuum drum  144  connected to a vacuum source V is mounted adjacent the driven belt  140 . The strip of material  14  is fed between the belt  140  and the vacuum drum  144  thereby drawing air from the material to cause compression. This precompression assists in achieving a highly compressed package  10  but is not necessary to form a package  10  in accordance with this invention.  
     [0092] If desired, the same apparatus described above can be used to unwind the package  10  at an end use station so that the package  10  can be accurately driven by a belt based on the measured tension at the pay-off or measured required line speed. The package  10  can be braked and driven at exactly the required speed without tensioning the strip  14  so that the strip  14  can be paid off at a very low or minimum tension. By this, expansion of the package  10  can be controlled precisely in a symmetrical manner to the winding action to prevent uncontrolled expansion of the layers creating localized stretching and potential damage of the material  14 . It should be noted, however, that packages  10  wound by this method without tension induced in the strips  14  naturally hold their shape and are formed as stable structures due to the coefficient of friction between the layers. The packages  10  in accordance with this invention do not necessarily require exterior wrapping as they resist uncontrolled expansion and do not exhibit a springing or popping effect when unbound.  
     [0093] The types of packages that can be made using this method and/or this apparatus include rolls carrying extremely long lengths of material. For example, the strip of material  14  may range from 5,000 feet to 100,000 feet or more. The package  10  may be a small roll of several feet diameter or a large roll, 3 feet wide with a diameter of 4 feet, for example. The material can have any thickness. The method is particularly suited for strips having a thicknesses of about 5 mm, 3 mm, or 1 mm, for example. The width of the strip may also vary and can range from the length of the core to thin strips of 25 cm or 10 cm. The material may also have various weights. For example, the weight may range from 20 grams per square meter (gsm) to 500 gsm or 40 to 50 gsm. The method is particularly suited for high speed operation, as in an industrial setting. For example, the material may be wound at speeds up to 500 meters per minute. These values are not intended to be limiting, but to merely provide examples of suitable material for this invention.  
     [0094] Various modifications and changes may be made within the scope of the invention. As noted above, the method and apparatus are suitable for a wide variety of materials, especially compressible materials. The method may be used to make single or multiple packages that are packaged singly or together. The apparatus may be adapted to accommodate different compression requirements and may vary based on different type of supply arrangements. It may be used at the initial phase of forming the material and creating a master roll and/or may be used in downstream operations including separating smaller widths of material from the master roll or even by an end use manufacturer that handles only small rolls of material.