Abstract:
A method and apparatus for winding strip material onto a drum is disclosed. Friction between the surface of the drum and the strip material wound there around, as well as friction between adjacent reels of strip material, may be selectively controlled by controlling the provision of a fluid bed between the strip material and the surface of the drum. Control over this friction allows the individual strips to slip to different degrees relative to the drum on which they are wound. The different amounts of slip permit the strips to be wound on the drum with uniform tension and at a uniform take up speed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus for winding parallel strips of material, such as metal strips, onto a drum. 
     BACKGROUND OF THE INVENTION 
     Thin strips of material, such as steel, may be formed by slitting a wide web of material into a number of thin strips. For purposes of storage and shipping convenience, these thin strips of material may be wound onto a drum immediately following the slitting process. FIG. 1 shows three thin strips  20  of material, which have been slit downstream from a continuous web of material (not shown), being wound onto a drum  100  to form separate reels of thin strip material. 
     Because all thin strips  20  of material wound onto the drum  100  originate from the same wide web of material, it is desirable for all of the strips to be wound onto the drum at the same rate. If the strips  20  are not wound at the same rate, one of two conditions may occur. Winding a strip  20  at a rate that is slower than that of another reel on the drum may produce slack in the more slowly wound strip. Such slack may cause the strip  20  to be wound more loosely than is desired, and result in a drum with nonuniform reels of wound material. In extreme cases, such slack may accumulate to the point that it drags on the floor, or requires the creation of a large pit for accommodation of the slack. Alternatively, winding a strip  20  at a higher rate than other reels may produce excess tension in the more quickly wound strip. This tension may cause the strip to be wound too tightly, or in extreme situations cause damage to the strip or the apparatus used for the winding operation. 
     One hypothetical method of ensuring that all the strips are wound on a drum with uniform tension and at a uniform speed would be to make sure that all of the reels have the same thickness “d” throughout the winding process. Reels with the same thickness inherently take up thin strip material at the same speed. As shown in FIG. 1, however, it is not uncommon for the neighboring reels of thin strip material to have different thickness “d.” The production of reels with different thicknesses on the same drum may occur as a result of any of the following in isolation or combination: uneven wide web thickness, uneven coating thickness on the wide web, excessive/uneven burr on the wound strips, a loose leading strip edge, uneven applications of slitting lubricant, etc. Thus, it is not uncommon for the “natural” rate of strip take up to be different for the various reels on a drum. 
     It has been determined, however, that the “natural” rate of strip take up for each individual reel of strip material may be modified by providing for slip between the reel and the drum on which it is wound. In other words, the rate of take up of each individual strip may be controlled. 
     One known method of controlling the take up speed of each strip on a drum is described in, Lofstrom, Roger J.,  The Benefits and Limitations of Coreslip Rewinding , The Fabricator, October 1995, which is incorporated by reference herein. The afore noted article describes a Coreslip rewinding system in which the winding drum includes a number of outer drive rings on its outer surface. Each thin strip of material may be wound onto a separate drive ring. The drive rings may be made of plastic material, which provides them with the ability to slip relative to each other and the drum that drives them. The amount of “slip” of the drive rings is adjusted by adjusting the lateral pressure applied to the rings. The tighter the drive rings are squeezed together, the greater the friction between them, and the less they slip. By selectively adjusting the lateral pressure applied to the rings, the relative slip may be set so that each thin strip of material is wound under a relatively uniform tension. 
     While the foregoing Coreslip device provides the needed slip between adjacent reels, it does so at a cost. The plastic drive rings are susceptible to wear and heat, and may need to be changed frequently, raising cost and maintenance concerns. Furthermore, because each strip of material is subjected to the same amount of tension force, the strips must be of comparable width to avoid excessive loading of narrower strips. 
     Another known method of controlling strip take up speed is described in Lofstrom, U.S. Pat. No. 5,292,084 (Mar. 8, 1994). The Lofstrom patent discloses a core slip rewinding system in which each individual strip is wound over a series of roller bearings. The roller bearings underlying each reel are free to rotate independent of the neighboring roller bearings of other reels. As such this system may be capable of reducing the friction between the reels and the drum to near zero levels. Although this system may be very effective, it suffers from being relatively expensive to manufacture compared to alternatives. Furthermore, such a system can only accommodate one size of drum. 
     Upon study of the foregoing Lofstrom devices, it became apparent to the present Applicant that a preferable winding apparatus would provide near zero friction between the wound material and the core on which it is wound. Any friction that is needed to control the amount of slip between the wound material and the core may be provided by laterally squeezing the strips of wound material together. By limiting the friction providing component to one parameter, precise control may be exercised over the amount of relative slip between the strips of wound material. While the later Lofstrom device provides the low friction required, it does so at the cost of monetary expense and limited versatility. 
     Therefore, there is a need for a method and apparatus for winding strip material that is more economical to produce and maintain than previously known systems. There is also a need for a method and apparatus for winding that is easier to operate, able to accommodate a wider selection of drum sizes, and does not require a slack pit. There is also a need for such a system that provides improved control over the relative slip between strips of wound material using lateral pressure. 
     In response to these needs, the present applicant has developed a method and apparatus for winding strip material on a drum which differs from the systems described above. In a first embodiment of the applicant&#39;s invention, a cushion of fluid, preferably air, may be selectively provided between the winding drum and the strip material wound thereon to reduce the friction there between. 
     OBJECT OF THE INVENTION 
     It is therefore an object of the present invention to provide a method and apparatus for reducing friction and/or controlling the amount of friction between a winding drum and the material wound thereon or therearound. 
     It is another object of the present invention to provide a method and apparatus for selectively adjusting the amount of slip between a winding drum and a reel of wound material. 
     It is still another object of the present invention to provide a method and apparatus for reducing friction and/or controlling the amount of friction between individual strips of material wound on a winding drum. 
     It is yet another object of the present invention to provide a method and apparatus for winding strip material that is more economical than previous methods and apparatuses. 
     It is still yet another object of the present invention to provide a method and apparatus for winding strip material that requires less maintenance than previous methods and apparatuses. 
     It is still another object of the present invention to provide a method and apparatus for winding strip material that can accommodate different sized winding drums. 
     It is still another object of the present invention to provide a method and apparatus for supplying a bed of pressurized fluid between the outer surface of a winding drum and material wound thereon. 
     It is still yet another object of the present invention to provide a method and apparatus for controlling the pressure of a fluid provided between the outer surface of a winding drum and material wound thereon. 
     Additional objects and advantages of the invention are set forth, in part, in the description which follows, and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention. 
     SUMMARY OF THE INVENTION 
     In response to the foregoing challenges, applicant has developed an innovative apparatus for winding strips of material comprising: a drum adapted to rotate about a longitudinal axis, said drum having a winding surface; a plurality of openings provided in the drum winding surface; and a means for supplying pressurized fluid to the openings. 
     Applicant has further developed an innovative apparatus for winding strips of material fed to the apparatus from a slitting machine, said apparatus comprising: a rotary arbor; a drum having an interior and a winding surface, said drum removably mounted on the rotary arbor; a plurality of openings providing communication between the drum interior and the drum winding surface; a pressurized fluid source; and at least one pressurized fluid passage connecting the pressurized fluid source to the openings. 
     Applicant has still further developed an innovative method of controlling the amount of friction between the winding surface of a drum and a plurality of material strips wound around said drum, said method comprising the steps of: providing a core insert around the drum winding surface; winding a strip of material around the core insert; and providing fluid between the winding surface and the core insert. 
     Applicant has still yet further developed an innovative method of reducing the amount of friction between the winding surface of a drum and a plurality of material strands wound around said drum, said method comprising the steps of: winding at least two strands of material around the drum winding surface; and supplying above ambient pressurized fluid to the winding surface. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated herein by reference and which constitute a part of this specification, illustrate certain embodiments of the invention, and together with the detailed description serve to explain the principles of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein. 
     FIG. 1 is a pictorial view of three strips of material being wound onto a drum operated in accordance with the present invention. 
     FIG. 2 is a pictorial view of a winding drum constructed in accordance with a first embodiment of the invention. 
     FIG. 3 is a partial cross section of the winding drum shown in FIG.  2 . 
     FIG. 4 is an end view of the winding drum shown in FIG. 3 showing external features of the end. 
     FIG. 5 is an end view of the winding drum shown in FIG. 3 showing internal features of the end. 
     FIG. 6 is a partial cross section of the winding drum shown in FIG. 3 showing material wound thereon. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A first embodiment of the invention is described in connection with FIG. 2, which shows an apparatus  10  used to wind strips of slit material. The apparatus  10  includes a winding drum  100  mounted on an arbor  200  and adapted to receive pressurized fluid from a fluid source  142  for distribution along the outer winding surface  110  of the drum. It is understood that the arbor  200  may be connected to a motor system (not shown) used to rotate the arbor and the winding drum  100  as a unit. 
     The drum  100  may be constructed of steel so as to provide adequate support for the heavy loads it is required to withstand. The drum outer winding surface  110  may be chrome-plated (e.g. using an Armoloy coating) and/or ground to a high finish to provide a high degree of lubricity and a hardness value in the range of 70 to 72. Whether coated or not, it is preferable that the winding surface  110  be very smooth so that friction between the winding surface and the material wound thereon is minimized. 
     The drum  100  may include slots  150  extending substantially the entire longitudinal dimension of the drum winding surface  110 . The slots  150  may communicate with the interior of the drum  100  through one or more holes  155  extending from the bottom of the slots into the drum winding surface  110 . The slots  150  preferably do not extend through the entire thickness of the winding surface  110  because this could weaken the drum&#39;s ability to withstand the loads applied to it during a winding operation. The drum  100  may also include first and second ends  120  and  130  which provide additional support for the drum. 
     The drum  100  is shown in cross section in FIG.  3  and in end views in FIGS. 4 and 5, and in which like reference numerals refer to like elements. The drum  100  may be locked to the arbor  200  with a key  210  that engages notches in the arbor and the drum ends  120  and  130 . The key  210  may be fixed to the arbor  200 , but unfixed relative to the drum  100 , enabling empty drums to be slid onto the arbor and full drums to be slid off of the arbor. 
     With specific reference to FIG. 3, the first end  120  of the drum  100  includes a number of separate elements that collectively provide a means for applying lateral pressure to the material to be wound on the drum  100 . The first end  120  includes an end cap  121 , a circular end plate  122 , a receiver  123 , a crosspiece  124 , a knurled knob  125 , a stud  126 , a ball plunger  127 , a pressure disc  128 , and a fluid cylinder  129 . The pressure disc  128  (preferably made of aluminum) is supported by the stud  126 . The fluid cylinder  129  is attached to the pressure disc  128 . A rotary fluid coupling  140  may be connected to the fluid cylinder. The rotary fluid coupling  140  may be supplied with pressurized fluid, such as air, from a fluid source (not shown) which causes the fluid cylinder  129  to push the pressure disc  128  against material wound on the drum  100 . This lateral pressure may be used to control slip between the strips of material wound on the drum. 
     With renewed reference to FIGS. 3,  4  and  5 , fluid dispersed on the surface of the drum  100  is fed from the second end  130  of the drum. Fluid may be supplied through a central passage  220  in the arbor  200  to one or more arbor fittings  230 . The one or more arbor fittings  230  may be connected by external hoses  232  to one or more second end fittings  132 . Each of the second end fittings  132  may provide connection between one external hose  232  and a plurality of individual internal hoses  134 . Each of the internal hoses  134  may be connected to a hole  155 . 
     With reference to FIG. 6 in which like reference numerals refer to like elements, individual strips  20  of slit material may be wound on the apparatus  10  as follows. The strips may be initially taped or fixed by another temporary means to the core inserts  30  that are preferably made of cardboard. The drum  100  may then be rotated by the arbor  200  so that the strips  20  are taken up and wound onto the drum. As the drum  100  is rotated, pressurized fluid, such as air, is supplied through the central passage  220 , arbor fittings  230 , external hose  232 , second end fittings  132 , internal hoses  134 , and holes  155  to the slots  150 . The fluid provided to the slots  150  is distributed onto the drum winding surface  110  and lifts the core inserts  30  off of the surface such that a fluid bed  50  is created between the winding surface and the core inserts. The existence of this fluid bed reduces friction between the drum winding surface  110  and the wound material, and permits the wound material to slip relative to the drum winding surface. 
     Each of the core inserts  30  may be separated from the neighboring insert by a divider  40 . Control over the slip between the core inserts  30  and the winding surface  110  is exercised by controlling the amount of lateral pressure applied by the plate  128  to the core inserts. Increased lateral pressure on the core inserts  30  increases friction and decreases the relative amount of slip between the core inserts and the winding surface. Control may be exercised such that each strip  20  of material wound onto the drum  100  may slip to the degree necessary to keep the tension applied to the strips relatively uniform. Means may be included for constant adjustment of the lateral pressure applied to the core inserts depending upon coil weights. Typically, lateral pressure may be set such that the rotational speed of the drum  100  is approximately ten (10) percent greater than the rotational speed of the wound material. 
     When the fluid supplied to through the central passage  220  of the arbor is air, the pressure supplied is kept relatively constant at a level in the approximate range of 80 to 120 psi. This pressure may be set as needed depending upon the density, thickness, width, and inherent “stickiness” of the core inserts. 
     In an alternative embodiment of the invention, the fluid supply  142  may provide a fluid(s) other than air in addition to air, or instead of air. For example, mixtures of air and vegetable oil based fluids are contemplated. 
     It will be apparent to those skilled in the art that various modifications and variations may be made in the preparation and configuration of the present invention without departing from the scope and spirit of the present invention. For example, the arrangement of holes and slots in the drum winding surface may be modified so long as some means for transferring pressurized fluid to the winding surface is provided. Furthermore, the individual components used to supply pressurized fluid to the drum slots may also be modified, eliminated, or added to, so long as some means for supplying pressurized fluid to the slots and/or the drum winding surface is provided. Thus, it is intended that the present invention cover all of the modifications and variations of the invention so long as they come within the scope of the following claims.