Patent Publication Number: US-6340126-B1

Title: Devices and methods for unwinding elongate materials

Description:
FIELD OF THE INVENTION 
     The present invention relates to systems and components for paying-off an elongate material, and more particularly, to devices for transferring the pay-off of the elongate material from one rotating package to another. 
     BACKGROUND OF THE INVENTION 
     The capacity of a roll of material used in a manufacturing operation may be insufficient for a production run, which can lead to undesirable results, for example, either a residual amount of material is left on the roll or the material can be consumed before the production run has ended. In the first case, the partial roll requires extra inventory space, or it may be discarded as scrap. When the material on a roll is less than is required for a full production run, the roll may be required to be changed out, or two rolls may be spliced together one or more times during the production run. Both the roll changing and splicing operations undesirably contribute to manufacturing costs and delay. 
     Pay-off devices are often used to unwind or “pay-off” the material on pads, for example, armor tape used in optical cable manufacturing operations. Respective pay-off devices may hold more than one pad of material, but can require an interruption in the operation for splicing. In order to reduce the frequency of splices, and reduce the likelihood of operator error, large bulk volumes of wound tape referred to as “packages” may be used. A package is made up of many layers of tape wound along the length of a tubular core and may include side flanges. 
     A variable accumulator/dancer is typically positioned between the pay-off device and the production line to compensate for any substantial differences between the tape pay-off feed rate and production line tape demand rates, typically measured in feet per minute. A accumulator/dancer typically has opposing sets of rollers that the tape is fed through. One of the sets of rollers can move relative to the other set to increase or decrease the length of tape accumulated within the accumulator/dancer to account for the tape rate difference. The accumulator/dancer senses the tape feed rate from the pay-off device and, through a feedback control loop, controls the rotational speed of the pay-off to tape rate difference to a minimum. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention encompasses an unwinding apparatus. The unwinding apparatus includes a pay-off device having a motor, a brake and a shaft rotatable about a longitudinal axis, wherein the motor and the brake control the rotational speed of the shaft. The unwinding apparatus includes a transition device having a first package having a first core. The first core has an axis of rotation, the first core being mounted on a rotatable shaft having a length of a first elongate material having a tail end. The unwinding device includes a second package having a second core, the second core having an axis of rotation generally coaxially aligned with the first core axis of rotation, the second core having a length of a second elongate material having a head end. The transition device supports at least a portion of one of the elongate materials, the first elongate material being contiguous with the second elongate material by means of a connection therebetween, so that pay-off between the first and second packages occurs essentially without interruption. 
     Another aspect of the invention includes a package having a length of elongate material wound about a core of the package. The package includes a primary core portion and an extended core portion contiguous with the primary core portion, the extended core portion extending beyond a radial side of the package. In addition, the length of elongate material defines a body portion and a tail portion, the body portion being wound about the primary core portion, the tail portion being contiguous to the body portion and wound about the extended core portion, the length of the body portion of the elongated material being greater than the length of the tail portion of the elongate material. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of an exemplary unwinding apparatus according to the present invention including first and second packages of wound tape connected by a transition device, all mounted on a rotating shaft of a pay-off device feeding an accumulator dancer. 
     FIG. 2 is a front view of the dancer of FIG.  1 . 
     FIG. 3 is a front view of the first and second packages and transition device mounted on the rotating shaft of the pay-off device, with a partial cross-sectional view of the first package. 
     FIG. 4 is a graph generally representing the shaft rotations per minute (rpm&#39;s) and the corresponding pay-off rate of the tape with and without the transition device. 
     FIG. 5 is a cross-sectional view of the first package. 
     FIG. 6 is an alternative embodiment of a transition device with a conical surface. 
     FIG. 7 is an alternate embodiment of a transition device with a conical surface and retaining members. 
     FIG. 8 is an alternative embodiment of a transition device with a conical surface having grooves. 
     FIG. 9 is an alternative embodiment of a transition device having a stepped conical surface. 
     FIG. 10 is a top view of the tape transition from one step to the next in the transition device of FIG.  9 . 
     FIG. 11 is an alternative embodiment of a transition device having a support surface formed by the layers of the tape windings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, an unwinding apparatus  10  according to the present invention is shown. Unwinding apparatus  10  provides for continuous pay off of an elongate material, for example, tape, glass fiber, filament, strand, wire, twine, optical ribbons, film, or cable. The elongate material can be metallic and/or non-metallic. In the preferred embodiment, the elongate material is a tape  12  extending between a first wound tape package  14  and a second wound tape package  16  transferable by a transition device  18 . 
     Unwinding apparatus  10  further includes a pay-off device  20  that rotates the first and second packages  14  and  16  to feed tape  12  into a variable accumulator or dancer  22 . In the manufacture of optical fiber cable, for example, dancer  22  transfers tape  12  to a production line that wraps the tape around the optical fibers to protect the fibers from damage. To avoid stopping or slowing the production line, transition device  18  transfers the unwinding of tape  12  from package  14  to package  16  in a gradual manner. Unwinding apparatus  10  controls tension in the tape by way of transition device  18  providing a tape-supporting surface that progresses from the level of the end of tape  12  at a core of first package  14 , to the outer diameter of second package  16 . 
     Pay-off device  20  includes a motor  24  for driving a rotatable shaft  26  that mounts the first and second packages  14  and  16  and transition device  18 . Rotatable shaft  26  includes conventional, releasable locking mechanisms (not shown) that secure packages  14 ,  16  and transition device  18  to the shaft to prevent their rotation relative to the shaft. The respective locking mechanisms are preferably independently releaseably lockable. The pay-off also includes a conventional braking mechanism  28  to slow or stop the rotation of shaft  26 . 
     Referring to FIG. 2, tape  12  is fed from pay-off device  20  and is received by accumulator/dancer  22 , which includes a series of rollers  30  that guide the tape to the production line (not shown). Within rollers  30  are opposing sets of rollers that provide dancer  22  with the capacity to accumulate a given length of tape  12 . Increasing the number of and distance between opposing rollers increases the accumulation capacity of dancer  22 . Preferably, rollers  30  include at least one variably-mounted roller  32  (two are shown in the Figures) having a distance to its opposing roller that varies with the incoming rate of tape  12  to enable dancer  22  to accommodate differences between the outgoing and incoming rates of tape. Each of rollers  30  and  32 , for example, includes a rotatable body mounted by bearings onto a shaft. Additionally, rollers  32  are mounted on a movable block  34 , which may be weighed down, such that when the incoming tape rate is less than the outgoing tape rate, the distance to the opposing rollers decreases. In contrast, when the incoming tape rate is greater than the outgoing tape rate, the distance to the opposing rollers increases. A sensor  36 , which may ride along a shaft  38 , is connected to block  34  and senses the relative position of rollers  32 . A signal is sent via signal wire  40  representing the relative position to motor  24  to control the rotational speed of shaft  26  to adjust the rate of tape  12  being fed to dancer  22  so that the pay-off rate is at least generally commensurate with the demand rate. 
     Referring to FIGS. 1 and 3, one embodiment of transition device  18  comprises an elongated surface  42  arranged in the form of a generally conical helix to support tape  12 . The generally conical helix progresses along a slope S (FIG.  3 ). Surface  42  of transition device  18  is preferably supported by a plurality of spoke members  43  (FIG. 1) radially extending from a cylindrical hub member  45 , which is mountable onto shaft  26 . Transition device  18  may also include a side wall  44  extending from each edge of surface  42  to form a tape-receiving channel  46  to contain tape  12 . At least one flange  44  is preferably positioned on the cone apex-side of surface  42  to contain tape  12  on the surface, as the tension in tape  12  urges the tape toward the apex of the conical helix. Alternatively, instead of a continuous flange  44 , spaced apart extending members such as pins or intermittent flange portions may be utilized. The conical helix surface  42  gradually and generally helically ramps from a first radius r 1 , (FIG.  3 ), substantially corresponding to the distance from the axis of rotation A—A to the level of the core  48  of a package, to a second radius r 2 , substantially corresponding to the distance from the axis of rotation A—A to the level of the outer tape diameter  50  of a package. Surface  42  may be substantially parallel to axis A—A, or the surface may be at an angle relative to axis A—A. 
     Transition device  18  advantageously provides a path for tape supporting surface  42  that is longitudinally extended along axis A—A (FIG.  3 ). This path allows the elongated supporting surface  42  to act as an accumulator for a length of tape  12 , where the accumulation capacity may be increased by increasing the longitudinal length of transition device  18 . Further, the accumulation capacity of transition device  18  is affected by the slope S of the conical helix (FIG.  3 ), where a more gradual slope exists, relative to axis A—A, a greater capacity is provided by increasing the total length of the path. Preferably, the generally helical path of surface  42  is longitudinally extended such that adjacent surfaces do not overlap. The elimination of overlapping portions of surface  42  advantageously allows tape  12  to be supplied from one point on the surface without interference from another portion of the surface, thereby preventing damage to or breakage of the tape. 
     Referring to FIG. 4, transition device  18  advantageously provides a smooth transition of tape  12  from first package  14  to second package  16  so that the tape is ultimately integrated into the cable product at a normal line speed rate LS. The accumulator/dancer keeps the tape feed at the normal rate LS during pay of the first package with a controlled +/− variation. When the transition device is active, the gradual change of the radius of surface  42 , combined with the accumulation capacity, allows time to reduce the rotations per minute (rpm&#39;s) of shaft  26  and packages  14  and  16 . The change in rpm is done by applying maximum braking power to the rotatable shaft or motor. The pay-off rate from the packages initially climbs above, falls below, and then again attains the LS rate during pay off of the second package (FIG.  4 ). Transition device  18  advantageously allows variable roller  32  to accumulate and then dispense the tape thereby eliminating the potential for a huge over capacity of the tape and avoiding any impact on the cable product. Further, the gradual change improves the tension control during the transfer. By transferring tape  12  from the end of one package to the beginning of another package, transition device  18  advantageously allows all of the tape on a package to be utilized, thereby eliminating waste and extra cost. Additionally, by enabling the use of connected bulk packages, transition device  18  reduces the number and frequency of required splicing, thereby saving time. Further, transition device  18  increases safety by reducing handling of the tape. 
     When joining together tape  12  from packages  14  and  16  through transition device  18 , the tail end  52  of the tape from one package is joined to the head end  54  of tape from the beginning of the other package with a splice  56  (FIG.  3 ). Suitable types of splices  56  include, for example, welding, heat seal, tape, glue, and soldering. In order to load tape  12  into transition device  18 , preferably enough tape is unwound from each package  14  and  16  to allow an operator to make splice  56  between ends  52  and  54 . Preferably package  14  is held stationary while package  16  is rotated to take up any slack. Spliced tape  12  is then positioned within channel  46  from a first end of transition device  18 , corresponding to the first radius r 1 , to a second end of transition device  18 , corresponding to the second radius r 2 . Tape  12  is tightened against surface  42  by using the engageable locking mechanism (not shown) of pay-off device  20  to selectively secure one package relative to shaft  26 , and then rotating the transition device  18  and the other package. Tape  12  is thereby supported by surface  42  during the entire transition from first package  14  to second package  16 . 
     In a traditional package, the tail end  52  of the wound tape is covered by the outer windings, making it difficult or impossible to unwind the tail without first unwinding the entire package. However, referring to FIG. 5, package  14  preferably includes a core  58  having a primary core portion  60  and an extended core portion  62 . Body portion  64  of the length of tape  12 , which is substantially the entire length of the tape, is wound in a plurality of layers about the primary core portion  60 . Tail portion  66  of tape  12 , which is a length of the tape at the end of the package, is wound about extended core portion  62 . Tail portion  66  of one package is thereby separately unwindable from core  58  to permit joining with a head portion  68  (FIG.  3 ), which is a length of tape at the beginning or outer diameter of body portion  64  of another package. For example, tail portion  66  may be of a length that allows an operator to position together the end of the tail portion of one package and the end of the head portion  68  of another package to operate a welding machine to make splice  56 . Preferably packages  14  and  16  are essentially identical at the beginning of a run. However, more than two packages can be placed side by side on shaft  26  with respective transition devices disposed therebetween for a continuous feed of material in seriatim from the packages. In winding tape  12  about core  58 , a tail end  70  of the tape is first positioned on the core and a first layer of tape is wound about the entire length of the core. A plurality of intermediate layers of tape  12  is then wound only about the primary core portion  60 . Therefore, a total length of the tape  12  on a package  14  or  16 , from tail end  70  at core  58  substantially corresponding to first radius r 1 , to a head end  72  at the outer diameter of the body portion  64  substantially corresponding to second radius r 2 , is preferably continuously wound about the core  58 . Although tail portion  66  of tape  12  has been described as being wound about the extended core portion  62 , one skilled in the art would realize that the tail portion may be otherwise accessible. 
     Transition device  18  may be fabricated from metal, plastic or any other suitable material. Although described with surface  42  and a tape-receiving channel  46  supported by spoke and hub members  43  and  45  (FIG.  1 ), transition device  18  can be formed, for example, from a solid or partially hollow material with an integral support surface. 
     Further, although transition device  18  has been described as a conical helix surface  42 , other similar configurations may provide a gradual tape transition from one package to another. Referring to FIG. 6, for example, a transition device  180  includes a conical support surface  182  formed in a solid or hollow configuration . In this embodiment, tape  12  (not shown) may be removeably held in place on the surface  182  by, for example, partial welding, tacking down or gluing. In another embodiment, referring to FIG. 7, a transition device  280  includes a generally conical support surface  282  having one or a plurality of retaining members  284  along a generally helical path radially extending outward from the surface. Retaining members  284  may include, for example, a continuous flange, segments of spaced-apart flanges, or a plurality of pins. In another embodiment, referring to FIG. 8, a transition device  380  may comprise a conical support surface  382  having a generally helical tape-receiving channel  384 . 
     In yet another embodiment, referring to FIG. 9, a transition device  480  comprises a stepped, tape-receiving surface  482  in the form of a series of steps of increasing diameter. To transition from one step to the next, referring to FIG. 10, tape  12  may be wrapped completely around a perimeter  484  of one step, including a lateral fold  486  (FIG. 10) so that the tape runs to the next step, then a lateral fold  486 ′ is made for wrapping around the next perimeter  484 ′. Each fold is, for example, partially welded, tacked, glued or otherwise removeably held in place on the surface  482 . The steps can be formed in a monolithic device  480  or a series of discs. 
     In yet another embodiment of the present invention, referring to FIG. 11, a transition device  580  has a support surface  582  that is formed by the tape windings  584  of package  586 . In this embodiment, the longitudinal length of each layer of tape  12  wound onto core  588  is controlled to provide the desired surface  582 , such as a stepped conical surface. 
     Although the invention has been described with reference to the preferred embodiments, other embodiments can achieve the same results. As such, variations and modifications of the present invention will be apparent to one skilled in the art and the following claims are intended to cover all such modifications and equivalents. For example, the extended core portion can take the shape of a radially extending flange of the package. The flange can have a spiral formed therein that functions as the transition device. The inventions described herein can be used to pay off essentially any elongate material in a factory or field environment. Where the package comprises flanges one flange can include a slit from the core to the outside diameter of the flange to accommodate the transition of the elongate material to the transition device and second package.