Patent Publication Number: US-2003227104-A1

Title: Core for winding material and method for manufacturing the same

Description:
RELATED APPLICATIONS  
       [0001] The application titled “GANG SAW SYSTEM FOR ROTATING AND SEGEMENTING A WORKPIECE”, having been filed concurrently with the present application, is hereby incorporated herein by reference.  
       TECHNICAL FIELD  
       [0002] The present invention relates to the winding of narrow width and thin gage ribbons of material such as aluminum and, more particularly, relates to the manufacture of the core upon which such materials are wound.  
       BACKGROUND OF THE INVENTION  
       [0003] The use of a core is widely used in many industries for the winding and unwinding of materials. A goal in each industry is to utilize a cost effective core in the manufacturing process. Also, each industry desires to utilize a core which has structural characteristics suitable for the particular material to be wound or unwound. Some materials require that the core, upon which it is wound, to have particular dimensional requirements as well as strength requirements. Moreover, some industries require that their cores not only be reusable, but be manufactured from readily available materials for cost effectiveness.  
       [0004] For example, aluminum producers typically require aluminum of a particular gauge and width be wound on a cardboard core. Although cardboard is cost effective to use, problems often occur which degrade the structural integrity of cardboard cores. One such problem is that cardboard cores are prone to shrinkage as a result of the changing moisture content in the cores. Another problem is that cardboard cores sometimes collapse because of insufficient strength. In response, some industries have attempted to utilize machined steel cores; but this is cost prohibitive. Moreover, the use of steel cores does not provided the desired dimensional requirements needed in most industries that utilizing some sort of winding or unwinding apparatus.  
       [0005] The cores upon which most materials are wound are typically circular with a hollow interior. Some industries require that the width and inner diameter of these cores have a particular dimension in order for the cores to be suitable for use with their winding or unwinding machines. However, manufacturing a core having the desired inner diameter, while utilizing readily available and cost effective materials, has proven difficult.  
       [0006] PVC (polyvinyl chloride) or some other thermoplastic resin, for example, is readily available and cost effective to use. PVC is typically manufactured in the form of elongated pipe of varying sizes. However, despite having available a wide range of PVC pipe, PVC pipe is not always available with the particular inner diameters need to permit use in common winding and unwinding machines. The inner diameter may be slightly narrower than desired. Also, the inner and outer diameters of common extruded PVC pipe are often irregular which makes ensuring uniformity difficult when placing a plurality of cores on an arbor of a winding machine. Moreover, when utilizing a PVC core, the PVC core often flexes during winding due to its thin walls. Therefore, in order to use a readily available material such as PVC to manufacture cores for winding and unwinding of a continuous web of material, the core may not only require resizing to permit its use on commonly available winding and unwinding machines, but the core may also require reinforcement in order to have the structural integrity needed to prevent flexing.  
       [0007] Therefore, there is a need for an improved core manufactured from a readily available and cost effective material. The new core must be able to maintain its structural integrity, even when placed under significant loads, while also being easily modifiable to permit being reconfigured to have particular dimensional requirements.  
       SUMMARY OF THE INVENTION  
       [0008] The present invention solves the above-identified problem by providing an improved core for winding a continuous web of material from readily available and cost effective materials. The core of the present invention may be resized to have the particular inner diameter required for use with common winding machines or may be modified to double its thickness to provide increased structural integrity.  
       [0009] Generally described, the present invention includes a rigid core for winding of material. The core has been reconfigured from once having a first inner diameter into having a second inner diameter. The core has been reconfigured by heating the core when having the first diameter and then stretching the heated core to then have the second inner diameter. As a result of resizing the core to have the second inner diameter, the core may be utilized in a winding machine for winding a continuous web of material.  
       [0010] According to one aspect of the invention, the core includes an first inner portion and a second outer portion. The second outer portion overlaps the exterior of the first portion. Either of the first inner portion and the second outer portion, or both, is reconfigured from once having a first inner diameter into having a second inner diameter by heating and stretching such that the second portion overlaps the exterior of the first portion and the resulting core is sized for use in a winding machine.  
       [0011] The foregoing has broadly outlined some of the more pertinent aspects and features of the present invention. These should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Other beneficial results can be obtained by applying the disclosed information in a different manner or by modifying the disclosed embodiments. Accordingly, other aspects and a more comprehensive understanding of the invention may be obtained by referring to the detailed description of the exemplary embodiments taken in conjunction with the accompanying drawings, in addition to the scope of the invention defined by the claims. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012]FIG. 1 illustrates a perspective view of one embodiment of a core of the present invention.  
     [0013]FIG. 2 illustrates a front view of the core of FIG. 1.  
     [0014]FIG. 3 illustrates an exploded view of the core of FIG. 1.  
     [0015]FIG. 4 illustrates the core of FIG. 1 wherein the inner and outer portions of the core are partially separated from one another.  
     [0016]FIG. 5 illustrates one embodiment of a plug for resizing a core.  
     [0017]FIG. 6 illustrates an alternative embodiment of a plug for resizing a core.  
     [0018]FIG. 7 illustrates a portion of a workpiece being placed over the plug of FIG. 5.  
     [0019]FIG. 8 illustrates the portion of the workpiece received on the plug and stretched to have an inner diameter that corresponds with the outer diameter of the plug.  
     [0020]FIG. 9 illustrates a plurality of cores made from the resized workpiece of FIG. 8.  
     [0021]FIG. 10 illustrates a perspective view of an alternative embodiment of a core of the present invention. 
    
    
     DETAILED DESCRIPTION  
     [0022] Referring now to the drawings in which like numerals indicate like elements throughout the several views, FIGS. 1 and 2 illustrate an exemplary embodiment of a core  10 , often referred to as a double core  10 , for receiving a continuous web of material. The core  10  may be used by a winding machine (not shown) to wind a continuous web of material such as aluminum.  
     [0023] Also, although the embodiments described herein are primarily directed toward the use of PVC or some other thermoplastic resin to manufacture the core  10 , the present invention contemplates the use of workpieces of any type of material which may be segmented into cores for winding a continuous web of material. The workpiece is typically cylindrical with a hollow center there through. Preferably, the workpiece is hollow PVC piping which may be cut into annular pieces. However, the workpiece may have any possible configuration suitable for being segmented into a plurality of cores  10  for receiving a continuous web of material.  
     [0024] As best shown in FIG. 3, one embodiment of the core  10  of the present invention includes a first inner portion  20  and a second outer portion  30 . The core  10  is commonly referred to as a double core  10 , as mentioned above, because it includes both the first inner portion  20  and the second outer portion  30 . Preferably, the first inner and second outer portions  20 ,  30  are made from plastic such as PVC. Moreover, the first inner and second outer portions  20 ,  30  may be made from the same portion of PVC piping. Because the core  10  includes both the first inner portion  20  and the second outer portion  30 , the thickness of the core  10  has been doubled. The increased thickness provides greater structural integrity to the core  10  which eliminates the problem with flexing as described above.  
     [0025] Preferably, the inner exposed surface of the first inner portion  20  has been roughed to provide a fraction bearing surface for users when transporting the cores  10 . The roughed surface  34  is generally shown in FIGS. 1, 3 and  4 . The roughed surface  34  may be created by hand using any available grinding apparatus.  
     [0026] A plurality of cores  10  may be manufactures from an elongated length of PVC piping. For example, a plurality of workpieces  60  may be cut from a single length of PVC piping and a plurality of first inner portions  20  and second outer portions  30  may then be made from the workpieces  60 . As explained above, in each core  10 , the outer portion  30  overlaps the exterior of the inner portion  20 . If the inner diameter of the inner portion  20  corresponds with the an inner diameter needed to permit use on a winding machine, no stretching is required and at least one of the workpieces  60  may be cut into a plurality of first inner portions  20  of the desired width. However, the inner diameter of the second outer portion  30  must then be resized such that it may be placed over the first inner portion  20  as shown in FIGS. 3 and 4. Resizing of a workpiece  60  to make a plurality of second outer portions  30  is explained in greater detail below.  
     [0027]FIG. 5 illustrates one embodiment of a plug  40  utilized in the resizing process. FIG. 6 illustrates an alternative embodiment of a plug  50 . In either case, the plugs  40 ,  50  are preferably aluminum and include a base  52  from which an elongated portion  54  extends upward. On top of the elongated portions  54  of the plugs  40  and  50  is a tapered nose portion  56  and  58 , respectively. The elongated portions  54  of each plug  40 ,  50  have different outer diameters and are primarily distinguishable based upon the height of each tapered nose portion  56 ,  58 . The taper is longer on plug  40  because of the larger amount of plastic it is capable of stretching. The plug  40  also includes an opening  59  which passes through the length of the elongated portion  54 .  
     [0028] The elongated portion  54  of each plug  40 ,  50  preferably is configured to receive a heated workpiece  60 , such as PVC, over its exterior as shown in FIGS. 7 and 8. The PVC workpiece  60  should be heated in an oven to approximately 260 to 330 degrees Fahrenheit. Preferably, the PVC workpiece  60  is heated to approximately 320 degrees Fahrenheit. Heating PVC to a temperature less than 260 degrees Fahrenheit may not have enough of an effect on the workpiece  60  to allow the workpiece  60  to be completely placed over the elongated portions  54  of the plugs  40 ,  50  and stretched as particularly shown in FIG. 8. Also, heating the workpiece  60  to a temperature beyond 330 degrees Fahrenheit can create a burnt appearance in the PVC workpiece  60 .  
     [0029] The elongated portion  54  of the plug  40  is preferably circular and has an outer diameter which is slightly larger than the desired inner diameter for each of the second outer portions  30  being manufactured. The diameter of the elongated portions  54  of the plugs  40 ,  50  must account for shrinkage of the workpiece  60  after cooling. For example, when stretching a workpiece  60  from having a 6.040 inch inner diameter to having a 6.625 inner diameter, the elongated portion  54  of the plug  40  has to have an outer diameter of approximately 6.675 inches. The outer diameter of the elongated portion  54  of the plug  40  is approximately 0.050 inches larger to account for shrinkage of the workpiece  60  after cooling.  
     [0030] In other examples, workpieces from commonly available PVC piping with inner diameters of 9.800 and 12.075 inches have been stretched to have inner diameters of approximately 10.020 and 12.100 inches, respectively. Separate plugs with the appropriate outer diameter should be used to stretch these larger workpieces. For example, a plug having an outer diameter of approximately 12.125 inches is needed for stretching PVC to 12.100 inches with shrinkage.  
     [0031] After resizing the workpiece  60 , the workpiece  60  will be cut to the appropriate widths to make a plurality of second outer portions  30 . Thus, the inner diameter of the second outer portions  30  now substantially correspond with the outer diameter of the first inner portion  20  such that each second outer portion  30  overlaps the exterior of a corresponding first inner portion  20 . The first inner and second outer portions  20 ,  30  may be friction fitted together or, preferably, adhesively bonded together with any suitable adhesive  66  typically used in PVC applications. Each pair of corresponding first inner and second outer portions  20 ,  30  are concentric with one another to define a double core  10  capable of being used in a winding machine. The outer diameter of each of the second outer portions  30  should be substantially similar to each other so that multiple cores  10  may be simultaneously lined up in a winding machine to wind a continuous web of material. The double cores  10  are rotated by the winding machine in order to accumulate the continuous web of material onto each double core  10 .  
     [0032] In an alternative embodiment, a workpiece may be stretched to increase its inner diameter by using the plug  50  shown in FIG. 6. In such case, the workpiece would then be cut into a plurality of annular portions  70  as shown in FIG. 9. Each annular portion  70  would then itself define a core  70  for winding a continuous web of material. Preferably, the cores  70  are used for winding and transportation of lighter materials compared to the materials wound and transported by the cores  10  described above. Also, the cores  70  are preferably made from PVC or some other thermoplastic resin.  
     [0033] The plug  50  is preferably used to stretch a workpiece approximately 0.100 inches. However, when using the plug  50 , the workpiece need not be heated as much as earlier described because the workpiece is not being stretched as much. For example, if plug  50  has an outer diameter of approximately 6.075 inches, the workpiece heated to approximately 280 degrees Fahrenheit may then be stretched from having an inner diameter of approximately 5.940 inches to having an inner diameter of approximately 6.040 inches. After cooling, the workpiece stretched by plug  50  may then be cut into a plurality of cores  70  for winding a continuous web of material. Preferably, each core  70  includes an exposed roughed surface similar to the roughed surface  66  described above.  
     [0034]FIG. 10 illustrates an alternative embodiment of the present invention. A core  90  includes an inner ring  92 , preferably made of steel, and an outer portion  94 , preferably made of PVC. The steel inner ring  92  is preferably made from flat stock steel cut into ⅛ inch thick by 1 inch wide elongated portions, which are then rolled into a ring. The outer portion  94  is sized to have the desired inner dimensions by heating and stretching as described above. The rolled inner ring  92  is then squeezed into the outer portion  94 . Preferably, when the steel is rolled to form the ring  92 , a gap is formed between the ends of the elongated portion so that the inner ring  92  may be squeezed together, to reduce its diameter, so that it will fit within the outer portion  94 . In FIG. 10, however, there is no gap shown because the ends of the inner ring  92  have already been squeezed together. The spring action of the inner ring  92 , because of the outward bias of the squeezed together ring  92 , will then force the inner ring  92  and outer portion  94  to remain together to form the core  90 . In addition, holes may be drilled into the portions of steel, before forming the rings, so that recessed screws  96  may be used to secure each inner ring  92  to the inside of an outer portion  94 .  
     [0035] The manufacture of the core  10 , described above, constitutes an inventive method of the present invention in addition to the core  10  itself. In practicing the method of manufacturing a core  10 , the steps include providing first and second annular portions  20 ,  30  having a first inner diameter. The method then includes heating the second annular portion  30 . Next, the method includes stretching the second annular portion with an annular plug  40 , as described above, such that the second annular portion has a second inner diameter. The method then includes the step of overlapping the exterior of the first annular portion with the second annular portions to define the core  10 .  
     [0036] The method of may also include the steps of cooling the second annular portion and adhesively bonding the first and second annular portions together.  
     [0037] The present invention has been illustrated in relation to particular embodiments which are intended in all respects to be illustrative rather than restrictive. Those skilled in the art will recognize that the present invention is capable of many modifications and variations without departing from the scope of the invention. Accordingly, the scope of the present invention is described by the claims appended hereto and supported by the foregoing.