Abstract:
The invention employs a fluid cushion between a shaft and cylindrical core to reduce friction between the core and shaft. Reduced friction at the shaft/core interface lowers the forces required to separate rolls of web material from the shaft. Lower separation forces should mean less damage to the wound web material and less wear and tear on the shaft and extraction equipment.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/535,875, filed Jan. 12, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to the production of rolls of web material wound on cores supported by a shaft of the machine producing the material and more specifically to removal of rolls of web material from the shaft.  
         [0004]     2. Description of the Related Art  
         [0005]     Significant losses in product can occur during the operation of extracting a shaft (reel spool) from cylindrical cores placed thereon to be wound with web materials. The losses occur because the friction forces between the inside diameter of the reel spool core and the outside of the shaft are sometimes high and therefore, significant force may be required to extract the shaft from the core. High shaft extraction forces can damage the wound web material, shaft, core and/or extraction equipment. The friction forces between the spool and core may be aggravated by the weight of the material being wound on the core and/or compression of the core in the radial direction due to the compressive forces caused by winding a web of material around the core.  
         [0006]     Many products, such as paper, tissue, textiles, plastics, films or polymer webs are wound on cylindrical cores in the machine producing the product. In this application, the word “web” will be used to refer to these materials and is intended to encompass all materials of a width greater than 10 inches (254 mm) that are wound onto any type of cylindrical cores, shafts or the like. Typically, the cores are cylindrical paper, cardboard or plastic tubes supported for rotation on shafts (also referred to as spools or reel spools) in the production equipment. The shaft and its fully wound roll or rolls of web material must be periodically removed from the production equipment and replaced with another shaft equipped with empty cores. The removed shaft is then separated from the rolls of web material, provided with empty cores and re-used.  
         [0007]     Past methods of separating the shaft from the rolls of web material have involved using a shaft-extracting device or a roll-extracting device. Shaft extracting devices typically support the roll of web material on a floor, table, or like surface, then attach an external device to the shaft and pull the shaft out of the roll core. Shaft extractors may be fixed, or adjustable in elevation.  
         [0008]     Roll-extracting devices separate the rolls from the shafts by fixing the shafts in a support device, which is usually cantilevered. The elevation of the shaft (and hence the rolls of web material) is changed to rest the outside surface of the wound web material on a cart, or the like. The cart is then moved in the opposite direction, away from the fixed support of the shaft, and pulls the rolls of web material axially off the shaft.  
         [0009]     Excessive shaft extraction forces may damage the cores, shaft, shaft extracting equipment and the wound web material.  
       SUMMARY OF THE INVENTION  
       [0010]     An object of the present invention is to provide a new and improved apparatus and method for reducing the friction between the core of a roll of web material and a shaft supporting the roll of web material.  
         [0011]     An aspect of the invention relates to producing a fluid cushion, preferably of compressed air, between the shaft and core (with the alternative introduction, application or activation of any solid, liquid or gas or other means as described below), to reduce friction between the core and shaft. Reduced friction at the shaft/core interface lowers the forces required to separate rolls of web material from the shaft. Lower separation forces should mean less damage to the wound web material and less wear and tear on the shaft and extraction equipment.  
         [0012]     According to further aspects of the present invention, the cushion/bearing material (encompassed by the term ‘fluid’, for the remainder of the specification) may be introduced to the core/shaft interface anywhere through the shaft structure. Alternatively, the fluid may be introduced directly between the reel spool and core, without first passing through the shaft itself. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a sectional view through a reel spool shaft and two rolls of web material, where the shaft is modified according to aspects of the present invention;  
         [0014]      FIG. 2  is a side view, partially in phantom, of an alternative reel spool shaft according to aspects of the present invention;  
         [0015]      FIG. 3  is an enlarged sectional view of the reel spool shaft of  FIG. 2 , taken along line  3 - 3  thereof;  
         [0016]      FIG. 4  is a side view, partially in phantom, of a further alternative reel spool shaft according to aspects of the present invention; and  
         [0017]      FIG. 5  is an enlarged sectional view of the reel spool shaft of  FIG. 4 , taken along line  5 - 5  thereof. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]     The web material, whether paper, tissue, textile, plastic, film or polymer web, is wound on cylindrical cores of paperboard, cardboard or plastic supported for rotation by shafts in or near the equipment producing the web material. The word ‘web’ is used herein to refer to all materials of a width greater than 10 inches (254 mm) that are wound onto any type of cylindrical cores, shafts, or the like. When taking up the web material, it is important for the core to rotate with the shaft and not independently of the shaft. This typically means that the cores are configured to fit snugly over the shaft. This snug relationship between the core and shaft may be aggravated by atmospheric conditions such as humidity, variation in the size of the cores, the weight of the wound web material and by compressive forces exerted on the core by the wound web material. In combination, these factors frequently result in frictional forces between the core of a roll of web material and the supporting shaft that can be difficult to overcome. Forces generated during attempts to remove frictionally engaged cores from their shafts are frequently of such a magnitude as to damage the wound web material, the core, the shaft and/or the shaft extraction equipment.  
         [0019]     The basic features of an exemplary embodiment are illustrated in  FIG. 1 . Rolls of web material  30  wound on cores  32  are supported on a reel spool or shaft  20 . The illustrated shaft  20  is hollow, although the shaft may be solid or partially hollow along its length. A shaft is modified with a connection for introducing a fluid, preferably air or some other gas to the core/shaft interface. The connection may be in any form or location where the fluid will penetrate a significant portion of the area  36  between the shaft and core. The connection may be located on an end of the shaft, as in  38   a  or  38   b . Alternatively, the connection may be positioned to inject air directly at the shaft/core interface  36  without passing through the shaft. In the context of this application, the term “aligned”, when referring to the relationship of the connection for introducing fluid, includes locations coaxial with the shaft axis of rotation and locations that are not coaxial with the shaft axis of rotation, but are substantially parallel thereto.  
         [0020]     The injection of a pressurized fluid at the interface  36  of the core  32  and the shaft  20  produces a cushion or “fluid bearing”  40  between the core and the shaft. The fluid bearing  40  alters the coefficient of friction between the core  32  and the shaft  20 , reducing the force necessary to produce relative motion between the core an the shaft.  
         [0021]     The connection for introducing fluid is provided with a source of pressurized fluid. While compressed air is the most cost-effective fluid for the purposes of the present invention, other compressed gasses or liquids are compatible with the invention. A variation of the invention uses a lubricant introduced between the outside of the shaft and the core to reduce the friction between the core and shaft. The lubricant may be a fluid substance (air, as in the base invention, or liquids), or dry lubricants, including but not limited to graphite. In some cases, a carrier fluid, such as compressed air may be used to disperse a liquid or dry lubricant at the shaft/core interface.  
         [0022]     An alternative embodiment of the inventive reel spool shaft  20   a  is illustrated in  FIGS. 2 and 3 . Shaft  20   a  is equipped with rolling elements  42  arranged to protrude through the shaft outside surface  44  to lower the forces required to remove the rolls of web material from the shaft. The rolling elements may be in a fixed location on the shaft relative to the center of spool rotation. Alternatively, the rolling elements may be movable as shown in  FIG. 3 , from a retracted position below the shaft outside surface  44  to an extended position where the rolling elements protrude from the shaft outside surface. The force to move the rolling elements  42  between the retracted and extended positions may be provided by pressurized fluid provided to the shaft through connection  38   a . Alternatively, the rolling elements  42  may be actuated by spring or electrical or mechanical means. The shaft outside surface  44  may be coated with a friction reducing coating  46  such as teflon to reduce friction between the core and the shaft at locations of contact with the shaft outside surface.  
         [0023]     Another alternative embodiment of the inventive reel spool shaft  20   b  uses low friction elements and/or materials on the shaft outside surface  44  of the shaft. As shown in  FIGS. 4 and 5 , the low friction materials are in the form of elongated bars  48  arranged to radially reciprocate between a retracted position below the shaft outside surface  44  to an extended position where the elongated bars  28  protrude from the shaft outside surface. The force to move the elongated bars between the retracted and extended positions may be provided by pressurized fluid provided to the shaft through connection  38   a . Alternatively, the elongated bars  48  may be actuated by spring or electrical or mechanical means. The shaft outside surface  44  may be coated with a friction reducing coating  46  such as teflon to reduce friction between the core and the shaft at locations of contact with the shaft outside surface. The elongated bars may be continuous along substantially the entire length of the shaft outside surface  44  or may be discontinuous longitudinally overlapping bars.  
         [0024]     The present invention is applicable for use in conjunction with any and all types of shaft-extraction and or wound roll removal devices. Exemplary embodiments of the present invention have been set forth for purposes of illustration. The foregoing description should not be deemed a limitation of the invention. Various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.