Abstract:
An automatic cable spooling device is provided, comprising a frame adapted to rotatably hold a spooling drum; a drum motor operatively connected to the drum; and a levelwind arm positioned adjacent to the drum. The levelwind arm is movable in a plane aligned with the rotational axis of the drum. The system further includes an arm motor operatively connected to the levelwind arm; and a microcontroller in communication with the arm motor. An arm encoder is adapted to sense a position of the arm motor and is in communication with the microcontroller. Likewise, a drum encoder is adapted to sense a position of the drum motor and is also in communication with the microcontroller. The position of the levelwind arm is controlled by the microcontroller based on the position of the drum, the spooling width, and a predetermined cable diameter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This nonprovisional application claims priority to U.S. Ser. No. 62/233,367, filed on Sep. 27, 2015. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The invention relates generally to devices and methods used to automatically and evenly spool cable, wire, line or lead rope, and more particularly to such devices and methods used to pull conductors in the electrical utility field. 
         [0006]    2. Description of Related Art 
         [0007]    Automatic spooling of cable on a drum for conductor pullers is usually done with a self-reversing leadscrew. This is a mechanical means to traverse a spooling head linearly back and forth similar to the manner in which fishing line is spooled on a bait casting reel. The linear speed of the spooling head is proportional to the rotational speed of the drum, where the drum and leadscrew are mechanically linked by a chain. Properly sizing the chain reduction, leadscrew pitch, and leadscrew groove length will spool the cable onto the drum somewhat evenly. However, since the prior art methods are a mechanical solution to proper spooling, all components must be designed, machined and assembled perfectly for it to work correctly. If the cable is not spooled properly, then cable life is decreased due to increased frictional wear and the machine will not work properly. Leadscrews require many parts that are quickly wearable and require frequent maintenance. Furthermore, the leadscrew is typically designed for one specific cable diameter. Therefore, if one cable is exchanged for another, or if the cable shrinks due to stretching, the leadscrew will not work properly, and a new leadscrew system needs to be installed. Also, because of the chain linking the leadscrew to the drum, the leadscrew may not be moved independently of the drum. 
         [0008]    Accordingly, what is needed is an improved method and device for automatically spooling cable, wire, line or lead rope on a drum which accomplishes at least the following objectives: (1) automatic cable spooling on the drum with a powered levelwind arm; (2) use of a controller to gauge drum speed and conversion to the appropriate levelwind movement based on the drum flange width and cable diameter; (3) use of a slew bearing and worm gear to support movement of the levelwind arm; (4) use of an encoder in the drum driveline to assist in establishing the proper cable position; and (5) use of an encoder on the worm gear for establishing the actual cable position. 
       SUMMARY OF THE INVENTION 
       [0009]    An automatic spooling system is provided in a preferred embodiment, comprising a frame adapted to rotatably hold a spooling drum, wherein the spooling drum includes a rotational axis, and a spooling width bounded by a first flange and a second flange; a drum motor operatively connected to the drum; a levelwind arm positioned adjacent to the drum, wherein the levelwind arm is moved in a plane aligned with the rotational axis of the drum; an arm motor operatively connected to the levelwind arm; an arm encoder in communication with the arm motor; a microcontroller in communication with the arm motor; an arm encoder adapted to sense a position of the arm motor and in communication with the microcontroller; a drum encoder adapted to sense a position of the drum motor and in communication with the microcontroller; and wherein the position of the levelwind arm is controlled by the microcontroller based on the position of the drum, the spooling width, and a predetermined cable diameter. 
         [0010]    In a further embodiment, the levelwind arm includes a plurality of sheaves adapted to guide a cable from a cable source into the drum. 
         [0011]    In another embodiment, the levelwind arm may be mounted to a slew bearing adapted to allow pivoting motion of the levelwind arm within the plane. 
         [0012]    The slew bearing includes a central opening for passage of a cable, and the arm motor is operatively connected to the slew bearing through a worm and worm gear system. 
         [0013]    The drum encoder is adapted to identify a required cable position, and the arm encoder is adapted to identify an actual cable position. 
         [0014]    In a further embodiment, the spooling system also includes a display in communication with the microcontroller adapted to receive input from an operator of parameters required to achieve an optimum wind of a cable around the drum. 
         [0015]    A method of spooling a cable is also provided, comprising the steps of providing a spooling system as explained above; setting a plurality of parameters in the microcontroller based on a position of the drum, the spooling width, and a predetermined cable diameter; and operating the spooling system to spool the cable. 
         [0016]    The above and other objects and features of the present invention will become apparent from the drawings, the description given herein, and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements. 
           [0018]      FIG. 1  illustrates a perspective view of a preferred embodiment of the present invention in the form of an automatic cable spooling device. 
           [0019]      FIGS. 2A-2C  illustrate top, side, and perspective views of the subassembly containing the levelwind arm, slew bearing, slew motor and drive, and the encoder. 
           [0020]      FIG. 3  illustrates a top view of the levelwind arm and guiding sheave relative to the drum flanges. 
           [0021]      FIGS. 4A and 4B  illustrate the manner in which the cable should be properly spooled on the drum using the present invention. 
           [0022]      FIGS. 5A-5C  illustrate top, side, and perspective views of a cable pulling device which incorporates a preferred embodiment of the present invention. 
           [0023]      FIG. 6  illustrates the cable pulling device of  FIGS. 5A-5C  in position to pull a cable through a conduit. 
           [0024]      FIG. 7  is a schematic diagram showing the power connections and communication between the slew and drum motors, slew and drum encoders, and the microcontroller. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Before the subject invention is further described, it is to be understood that the invention is not limited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims. 
         [0026]    In this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. 
         [0027]    As will be further described below with respect to the preferred embodiment, the present invention automatically and evenly spools cable onto a drum regardless of variations in cable size or other external factors. The system uses electronics to replace mechanical means of automatic spooling. Generally, a cable enters through the pivoting axis of a slew bearing and is directed through a plurality of sheaves onto a drum. A levelwind arm is driven back and forth based on a closed loop feedback system that relates the proper cable position to its actual position. The proper position of the cable is a function of variable drum rotation, drum width, and cable diameter. The drum and cable parameters may be modified at any time to accommodate the specifics of the spooling environment. 
         [0028]    In the preferred embodiment shown in  FIG. 1 , the automatic cable spooler of the present invention comprises a levelwind arm  1  having a first sheave  2 A positioned below a slew bearing  6 , and a second sheave  2 B positioned directly above a drum  11 . The levelwind arm  1  is rotatably mounted below the slew bearing  6 , while the slew bearing  6  is mounted to a spooler frame  40  as will be described elsewhere with respect to  FIGS. 5A-5C . As will be appreciated, the slew bearing  6  must be suitably strong to support high axial loads and similar forces from the levelwind arm  1  during spooling activities. A cable  10  is routed through the center of the slew bearing  6 , around the first sheave  2 A, around the second sheave  2 B, and then onto the drum  11 . Two guide pins  3  are positioned behind the first sheave  2 A, and a guide pin  3  and track roller  5  are positioned in front of the second sheave  2 B to ensure that the cable  10  remains securely within the second sheave  2 B. For the purposes of this application, the word cable shall be used, with the understanding that the invention applies equally to cables, ropes (including lead ropes to pull electrical cables), wires, and any other flexible lines which can be spooled around a drum  11 . 
         [0029]    The slew bearing  6  includes worm gear and worm system  8  operatively attached to the slew bearing  6  for causing the levelwind arm  1  to pivot back and forth as will be further described. A slew motor  9  is operatively connected to the worm drive  8 , along with a slew encoder  7  and a microcontroller  17  (such as a programmable logic controller, or PLC, having data storage and memory functionality), as further depicted in  FIG. 7 . The slew encoder  7  can be an incremental or absolute encoder and is either mounted on the opposite side of the worm gear or to an auxiliary shaft on the slew motor  9 . As will be explained elsewhere, the slew encoder detects and communicates to the microcontroller  17  the absolute position of the worm drive  8 , which can be correlated to the position of the cable  10  exiting the second sheave  2 B on the levelwind arm  1 . Alternatively, a linear actuator with a linear distance transducer may be used to rotate the levelwind arm  1  about the slew bearing  6 . In another possible embodiment, the levelwind arm  1  may be driven entirely by a linear actuator or equivalent motor and drive system that moves the levelwind arm  1  in a purely linear path relative to the drum  11 , rather than the slightly arcuate path enabled by the slew bearing  6  shown in the figures. In either case, however, control of the position of the levelwind arm  1  based on the parameters described herein and the method of achieving consistent levelwind results is within the scope of the present invention. 
         [0030]    The drum  11  includes side flanges  20  which are rotatably positioned within a drum frame  14 . A drum motor  12 , and typically a drum gear box  13  to increase drum motor torque, are operatively connected to the drum frame  14  and the drum  11  to rotate the drum  11  and spool the cable  10 . The drum motor  12  includes a drum encoder  16 , as further depicted in the schematic diagram of  FIG. 7 . 
         [0031]    The microcontroller  17  is initialized by the operator with the beginning position of the cable  10  on the drum  11 . As the drum  11  turns, the microcontroller  17  relates the drum encoder  16  pulses to the proper position of the cable  10  based on the particular characteristics of the cable  10  and drum  11  that are input into the microcontroller  17  via the display  30  on the cable spooler. The microcontroller  17  also receives positional data from the slew encoder  7  and calculates the actual position of the cable  10 . The microcontroller  17  then outputs signals to the slew motor  9  to move the levelwind arm  1  until the actual cable position equals the proper cable position, thus completing a closed loop feedback system. Inputs to the microcontroller  17 , such as drum width, cable diameter, and calibrated position function, may be modified at any time using the display  30 . 
         [0032]    With reference to  FIG. 7 , the microcontroller  17  bidirectionally communicates to the slew motor drive  26 , the drum motor drive  29 , and the display  30  over the CanBus with CanOpen, a digital communication protocol utilizing two channels, Can Hi and Can Lo. The user inputs desired drum  11  speed with the display  30 , which information is sent to the microcontroller  17 , and which is then filtered based on limiting parameters and finally sent to the drum drive  29  to carry out the motion desired. The actual movement of the drum motor  12  is communicated to the microcontroller  17  from the drum encoder  16  through quadrature pulses which can be translated into direction, position, speed and acceleration. The microcontroller  17  sends this information to the PID controller which then outputs a slew motor  9  speed that is sent to the slew motor drive  26 . Information attained from the slew motor drive  26 , drum motor drive  29 , slew encoder  7 , and drum encoder  16  are then passed from the microcontroller  17  to the display  30  for the user to see. 
         [0033]    In operation, to achieve the levelwind output position during spooling, an operator uses the display  30  to input the drum  11  width between the drum flanges  20 . Generally, this is accomplished by defining six positions of the levelwind arm  1  between one drum flange  20  to the other drum flange  20 . First, the operator is prompted by the display  30  to manually move the levelwind arm  1  until the center of the second sheave  2 B is directly over the first flange (left or right). With the second sheave  2 B and the level wind arm  1  in this initial position, the operator presses a button on the display  30  which records the corresponding slew encoder  7  position in the microcontroller  17 . The operator is then prompted to manually move the levelwind arm  1  until the center of the second sheave  2 B is one-fifth of the way between the two drum flanges  20 . With the levelwind arm  1  the second position, the operator presses a button on the display  30  which records the corresponding slew encoder  7  position in the microcontroller  17 . This sequential process of moving the level wind arm  1  and recording the position via the display  30  is repeated for each position at successive one-fifth distances from the initial drum flange  20  until the sixth and final position of the levelwind arm  1  is recorded at the second drum flange  20 . 
         [0034]    At this point, the microcontroller  17  has six points to plot a position profile. Between each point, the profile curve is linearized for simplification, because the error is small enough to neglect. The foregoing steps have now correlated the slew encoder  7  output to the levelwind arm  1  output position. To define the cable  10  position, the operator uses the display  30  to input the desired number of wraps on the drum  11  per layer into the microcontroller  17 . The operator also inputs the pulses per revolution of an incremental drum encoder  16 . The microcontroller  17  then calculates the total number of pulses per cable layer as well as the number of pulses per wrap. As the cable  10  enters and is aligned with the initial drum flange  20  and is tangent to the drum  11  from the levelwind arm  1  output sheave  2 B, the operator uses the display  30  to input this position as the starting point of the cable  10 . At this position, the microcontroller  17  resets its counts to zero. As the drum  11  turns, the drum encoder  16  outputs pulses to the microcontroller  17 . One full revolution of the drum  11  means the cable  10  should move exactly one wrap (or cable diameter) over, causing movement of the levelwind arm  1  to achieve this outcome. The spooling of the cable  10  continues until the total number of pulses per layer have been achieved, which is indicative that the cable  10  has completed a full layer and reached the opposite drum flange  20 , and now needs to travel back toward the initial drum flange  20  in half-wrap increments. 
         [0035]    At this point in the spooling process, each pulse from the drum encoder  16  is subtracted from the cumulative pulse count tracked by the microcontroller  17 . This continues until the pulse count reaches zero, indicating that the cable  10  has returned to the initial drum flange  20  and needs to change directions. Now that both the proper cable  10  position (cable position) and the actual cable  10  position (levelwind output position) are known by the microcontroller  17 , a closed loop feedback system can be used. For example, a proportional-integral-derivative (PID) feedback loop can be employed, where two variables (actual position and proper position) are present, and the controller calculates the error, or simply the difference, between the two variables. The controller also accepts constants such as proportional gain factor, integral gain factor, differential gain factor and min/max output values. The controller calculates the proportional, integral and differential of the error and multiplies each respective gain. The output of the controller is the sum of each of these except when they exceed the minimum or maximum values. When this system is in action, the levelwind arm  1  will always place the cable  10  in the proper position to wrap each layer on the drum  11 . Reversing the rotating direction of the drum  11  is easily accommodated by changing the pulse count direction. If a smaller or larger cable  10  is desired, the new number of wraps is entered via the display  30  into the microcontroller  17 . 
         [0036]      FIGS. 4A and 4B  illustrate a proper spooling orientation of the cable  10  around the drum  11 , wherein the cable  10  is wound in parallel half-wraps. Spooling on a drum  11  is best achieved by wrapping the cable  10  as close to parallel with the drum flanges  20  as possible. Because the wraps can only stay parallel for up to 360 degrees, the cable  10  must be shifted over in certain increments. For drums  11  around 14 inches in diameter and with cable  10  of one-half inch in diameter, shifting the cable  10  by one-half of the cable diameter at 180 degree increments works best.  FIG. 4B  shows how one layer should ideally be wrapped. As the drum  11  turns beyond this layer, the cable  10  will be forced up to the next layer and continue to lay on the previous layer except offset by one-half of the cable diameter as seen in the cross-sectional view of  FIG. 4A . 
         [0037]    To achieve parallel wraps, the levelwind arm  1  must be positioned directly in line and create a zero degree fleet angle between the sheave  2 B and correct cable wrap position on the drum  11 . The levelwind arm  1  will remain in this position until the drum  11  has rotated 180 degrees. At this point the microcontroller  17  establishes that the levelwind arm  1  must be moved until the “actual” levelwind arm  1  position equals the “proper” levelwind arm  1  position. As explained above, this result is achieved by a PID feedback loop where the error is calculated as the difference between the actual position and the proper position. The slew motor  9  speed and direction are determined by the output of PID loop. Once the error between the actual position and the proper position equals zero, the drum motor  12  will remain in that position until the next half-wrap position is requested. 
         [0038]    The above described spooling system may be used in a wide range of spooling applications. However, in a preferred embodiment, the spooling system can be incorporated into a larger machine designed for pulling conductor for electrical services. As shown in  FIGS. 5A-5C , a mobile, battery-powered winch is depicted as having a wheeled platform  25  and an upper frame  40 . The spooling system of the present invention is operatively attached to the frame  40  by mounting the upper portion of the slew bearing  6  to the frame  40 , while the drum frame  14  is mounted to the wheeled platform  25 . A conductor pulling arm  35 , usually referred to as a “boom” or “rear boom”, having appropriate sheaves and features allowing adjustment of length is also pivotally attached to the upper frame  40 . 
         [0039]    In operation, and as shown in  FIG. 6 , the mobile winch is positioned to pull a cable  10  through an underground conduit from a remote source conductor spool  45 . In typical cases, a pilot line (not shown) has been preinstalled within the conduit when the conduit was buried. This pilot line is used to pull the cable  10  from the mobile winch to the conductor end  45 . If the pilot line was not preinstalled, the pilot line may be blown with a compressor from the conductor end  45  to the cable end  10 . Once the pulling cable  10  has reached the conductor  45  end, the conductor  45  and the cable  10  are attached together with a swivel. The mobile winch then applies electrical power to the electric drum motor  12  to pull the cable  10  until the conductor  45  reaches the pulling end. The cable  10  is then detached from the conductor  45  and another pull may be made through a different conduit. 
         [0040]    All references cited in this specification are herein incorporated by reference as though each reference was specifically and individually indicated to be incorporated by reference. The citation of any reference is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such reference by virtue of prior invention. 
         [0041]    It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.