Abstract:
A method of forming a bulb in a cable bolt includes providing cable from a cable source, advancing the cable in a first direction, and forming a bulb in a portion of the cable while the portion of the cable is continuously advanced and while the cable is continuously provided from the cable source.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/590,010, filed Jan. 24, 2012, the entire content of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to cable bolts, in particular, to a method and apparatus for forming a bulb in a stranded cable bolt. 
         [0004]    2. Description of Related Art 
         [0005]    Cable bolts are used in the mining industry for their ease of handling and installation. Cable bolts are generally easier to fit into a borehole than the elongated rods of conventional rod bolt systems. Regardless of the height limitations in a mine, cable bolts may be adapted to boreholes of any length due to their flexibility. The strength capacity of cables exceeds that of conventional rod bolts and, therefore, cable is the preferred reinforcement for certain roof conditions. 
         [0006]    Cable bolts are typically installed by placing a resin cartridge including catalyst and adhesive material into the blind end of a borehole, inserting the cable bolt into the borehole so that the upper end of the cable bolt rips open the resin cartridge and the resin flows in the annulus between the borehole and the cable bolt, rotating the cable bolt to mix the resin catalyst and adhesive, and allowing the resin to set about the cable bolt. In such cable bolts, the resin is typically set at an upper portion of the cable bolt at the blind end of the borehole. The cable bolts are typically formed with one or more bulbs to increase the bonding between the bolts and the resin. 
       SUMMARY OF THE INVENTION 
       [0007]    In one embodiment, a method of forming a bulb in a cable bolt includes providing cable from a cable source, advancing the cable in a first direction, and forming a bulb in a portion of the cable while the portion of the cable is continuously advanced and while the cable is continuously provided from the cable source. 
         [0008]    The bulb may be formed by moving a bulb forming mechanism along with the cable. The method may further include cutting the cable to a preset length while the cable is continuously advanced by moving a cutting device along with the cable. The cutting device may have a first position and a second position spaced from the first position, with the cutting device moving between the first and second positions while cutting the cable to the preset length. The cable source may include a spool having a length of cable, and the cable may be provided from an inner portion of the spool. The bulb forming mechanism may be movable between a first position and a second position spaced from the first position, with the bulb forming mechanism moving from the first position to the second position while forming the bulb. The method may further include spooling the cable after being cut to a preset length onto a spooler. The bulb forming mechanism may move from the second position to the first position after forming the bulb. The method may further include forming a plurality of bulbs in spaced apart portions of the cable. The bulb forming mechanism may include first and second clamps, with the first clamp engaging the cable as the bulb forming mechanism moves along with the cable and the second clamp moving relative to the first clamp to form the bulb. The cable may be advanced via a drive mechanism. An entire portion of the cable extending from the cable source may be continuously advanced until the cable is cut to the preset length. 
         [0009]    In a further embodiment, an apparatus for forming a bulb in a cable bolt includes a drive mechanism configured to continuously advance a length of cable, and a bulb forming mechanism movable along a longitudinal axis defined by the length of the cable between a first position and a second position spaced from the first position. The bulb forming apparatus is configured to form a bulb on a cable while moving along with the advancing cable. 
         [0010]    The apparatus may further include a cable source configured to provide a length of cable. The length of cable extends to the drive mechanism and from the drive mechanism to the bulb forming mechanism. The apparatus may further include a cutting device configured to cut a length of cable to a preset length. The cutting device may be movable between a first position and a second position spaced from the first position. The bulb forming mechanism may include first and second clamps, with the first clamp configured to engage a cable as the bulb forming mechanism moves along with the cable and with the second clamp being movable relative to the first clamp to form a bulb on the cable. The bulb forming mechanism may include a motor to move the bulb forming mechanism between the first and second positions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic view of an apparatus for forming a bulb in a cable bolt according to one embodiment of the present invention, showing a first position of a bulb forming mechanism and cutting mechanism. 
           [0012]      FIG. 2A  is a schematic view of a spool of cable according to another embodiment of the present invention. 
           [0013]      FIG. 2B  is a schematic view of a spool mechanism according to a further embodiment of the present invention. 
           [0014]      FIG. 3  is a schematic view of the apparatus shown in  FIG. 1 , showing a second position of the bulb forming mechanism and cutting mechanism. 
           [0015]      FIG. 4  is a plan view of a bulb forming mechanism according to one embodiment of the present invention, showing a cable bolt prior to bulbing. 
           [0016]      FIG. 5  is a plan view of the bulb forming mechanism of  FIG. 4 , showing the cable bolt after a bulb has been formed. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, and derivatives thereof, shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. 
         [0018]    Referring to  FIGS. 1-3 , an apparatus  10  for forming a bulb in a cable bolt includes a spool  12  having a length of stranded cable  14  wound around to the spool  12  and configured to pay off cable from the spool  12  as indicated by direction A by rotating the spool  12 . Although the cable  14  is shown being advanced from an outer portion of the spool  12 , the cable  14  may also be spooled such that the cable  14  is advanced from a center or eye of a coil of cable as shown in  FIG. 2A . A drive mechanism  16  receives the cable  14  and is configured to advance the cable  14  in a direction corresponding to a longitudinal axis of the cable  14 . The drive mechanism  16  includes a measuring device (not shown), such as a set of measuring wheels, which allows the formation of bulbs at preset and varying intervals along the length of the cable  14 . In particular, the measuring device may include an encoder wheel driven by the moving cable that includes an optical sensor that provides pulses of light with each revolution of the encoder wheel. The length of cable  14  advanced is determined by the quantity of revolutions experienced by the encoder wheel. A programmable logic controller (PLC) (not shown) detects when a certain length of cable  14  has been advanced and controls the apparatus to form bulbs  20  at preset and varying intervals along the length of the cable  14 . 
         [0019]    Referring again to  FIGS. 1-3 , a bulb forming mechanism  18  receives the cable  14  from the drive mechanism  16  and forms one or more bulbs  20  along the length of the cable  14  as controlled by the PLC or other suitable arrangement. The bulb forming mechanism  18  is mounted on a sliding frame shown schematically at  22  such that the bulb forming mechanism  18  is movable as indicated at B along a direction corresponding to the longitudinal axis of the advancing cable  14  to allow the bulb forming mechanism  18  to travel with the cable  14 . In particular, the bulb forming mechanism  18  is configured to form a bulb  20  on the cable  14  while the cable  14  is continuously advanced by moving with the cable  14  while forming the bulb  20 . In one embodiment, the bulb forming mechanism  18  includes a pair of clamps generally indicated at  24  that releasably engage the cable  14 . One of the clamps  24  is movable relative to the other clamp to buckle the strands of the cable  14  thereby forming the bulb  20  in the cable  14 . When the PLC initiates the bulbing sequence, the bulb forming mechanism  18  will clamp onto the cable  14  and travel along with the cable  14  while forming a bulb  20  at a specified location as determined by the measuring device and PLC. 
         [0020]    Once the bulb  20  is formed, the cable  14  will be released by the bulb forming mechanism  18  and the bulb forming mechanism  18  will move to its original position. Thus, the bulb forming mechanism  18  has a first position (shown in  FIG. 1 ) at the start of the bulb forming sequence and a second position (shown in  FIG. 3 ) spaced from the first position at the end of the bulb forming sequence. The bulb forming mechanism  18  will return to the first position after forming a bulb  20 . Because the bulb forming mechanism  18  is movable, the spool  12  and drive mechanism  16  can be continuously operated such that the cable  14  is continuously advanced without stopping any portion of the cable  14  to form the bulbs  20 . Such a continuous operation improves efficiency of the bulb forming operation by not having to start and stop the drive motors (not shown) powering the spool  12  and drive mechanism  16  and by not having stoppage time while the bulbs  20  are being formed. 
         [0021]    Referring again to  FIGS. 1 and 3 , in one embodiment, after forming one or more bulbs  20 , the cable  14  will continue passing through a cutting device  26 , such as a cut off saw, although other suitable cutting devices may be utilized. The cutting device  26  is mounted on a sliding table arrangement  28  in a similar manner as described above in connection with the bulb forming mechanism  18  such that the cutting device  26  is movable as indicated at C along a direction corresponding to the longitudinal axis of the advancing cable  14 . The cutting device  26  is configured to automatically cut the bulbed cable  14  to preset lengths, which are then bundled and packaged as shown at  30 . In another embodiment, as shown in  FIG. 2B , the cable  14  may also be passed through the cutting device  26  to a rewind spooler  32  to allow for spooling of longer bulbed cable bolts as indicated by direction D of the spooler  32 . The cutting device  26  has a first position (shown in  FIG. 1 ) at the start of the cutting process and a second position (shown in  FIG. 3 ) spaced from the first position at the end of the cutting process. The cutting device  26  will return to the first position after performing the cutting process. The movement of the cutting device  26  allows the cable  14  to be continuously advanced thereby allowing the cable  14  to have a positive velocity throughout the process. 
         [0022]    Referring to  FIGS. 4 and 5 , one embodiment of the bulb forming mechanism  18  is shown in more detail. The bulb forming mechanism  18  is supported by a frame  40  having a pair of parallel racks  42 . The bulb forming mechanism  18  includes a first clamp set  44  fixedly mounted to a base.  46  and a second clamp set  48  movably mounted to the base  46 . The second clamp set  48  is supported by a sliding bush and shaft arrangement  50 ,  52 . Each clamp set  44 ,  48  includes a pair of hydraulically operated mutually opposed jaws  54 ,  56  which are releasably engagable with the cable  14 . However, other suitable clamping arrangements may be utilized to grip the cable  14 . Double acting hydraulic cylinders  58 ,  60  are used to activate the first and second clamp sets  44 ,  48  to clamp the cable  14  therebetween. However, the double acting hydraulic cylinders  58 ,  60  may be substituted by single acting cylinders which activate the first and second clamp sets  44 ,  48  to clamp the cable  14  therebetween. 
         [0023]    The bulb forming mechanism  18  includes an actuator  62  in the form of a hydraulic piston with one end fixedly mounted to the base  46  and the other end movably mounted to the second clamp set  48 . The piston  62  provides movement of the second clamp set  48  towards the first clamp set  44  during the bulbing process. Alternatively, the single actuator  62  may be substituted by two actuators located on either side of the cable  14  with each actuator having one end fixedly mounted to the base  46  and the other end movably mounted to the second clamp set  48 . Other power sources, such as electricity, may be utilized to power the actuators. 
         [0024]    The bulb forming mechanism  18  includes a set of driven front pinions  64  and a complementary pair of rear idler pinions  66  in gearing engagement with the parallel racks  42  for enabling the clamp sets  44 ,  48  to move along with the cable  14  during the bulb forming process as described above. The front pinions  64  are preferably driven by a reversible, variable speed, hydraulic motor  68  with a built-in brake. A reversible, variable speed, electric motor with a brake could also be used for this purpose. Although the bulb forming mechanism  18  is movably mounted to the frame  40 , the bulb forming mechanism  18  may also be movably mounted to a ceiling rail, or other suitable arrangement, which runs parallel to the cable  14 . The bulb forming mechanism  18  includes one or more proximity sensors (not shown) for measuring the radial displacement of the bulb formed in the cable. The bulb forming mechanism  18  also includes an encoder  70  for controlling the movement of the pinions  64 ,  66  along the racks  42 . 
         [0025]    In use, the cable  14  is advanced across the length of the frame  40  with a portion of the cable  14  extending through the jaws  54 ,  56  of the first and second clamp sets  44 ,  48 . Oil pressure is then applied to the double acting hydraulic cylinders  58 ,  60  to respectively clamp the cable  14  between the jaws  54 ,  56  of the first and second clamp sets  44 ,  48 , as shown in  FIG. 4 . The hydraulic piston  62  is then activated to move the second clamp set  48  towards the first clamp set  44  forming a bulb  20  in the cable  14 , as shown in  FIG. 5 . As the cable  14  is clamped by the first and second clamp sets  44 ,  48 , the hydraulic motor  68  drives the pinions  64  to move the bulb forming mechanism  18  along with the cable  14  in a direction corresponding to the longitudinal axis of the cable  14 . Thus, the portion of the cable  14  where the bulb  20  is formed is continuously advanced. Radial displacement of the cable  14  may be controlled by the PLC using one or more proximity sensors (not shown) to limit the radial displacement of the bulb  20 . Once the first bulb is formed, oil pressure is applied to the hydraulic cylinders  58 ,  60  to release the cable  14  from the jaws  54 ,  56  of the first and second clamp sets  44 ,  48 . Oil pressure is then applied to the topside of the hydraulic piston  62  which in turn moves the second clamp set  48  back to its starting position, as shown in  FIG. 4 . After the bulbing process, the bulb forming mechanism  18  is in the second position as shown in  FIG. 3  and described above. The motor  68  then drives the pinions  64  along the racks  42  to move the bulb forming mechanism  18  to the first position, as shown in  FIG. 1  and described above, for performing further bulb forming processes. Although the first and second positions are generally mentioned, the bulb forming mechanism  18  may be moved as necessary to form one or more bulbs  20  on the cable  14  at predetermined positions while the cable  14  is continuously advanced. 
         [0026]    The bulb forming mechanism  18  described above and shown in the figures may take other forms as long as the mechanism for forming the bulbs is movable to allow the portion of the cable where the bulb is formed to be continuously advanced. In particular, the bulb forming mechanism  18  may be embodied as the bulb forming mechanism shown and described in U.S. Patent Application Publication No. 2011/0259072 to Evans et al. and U.S. Pat. Nos. 5,344,256 to Hedrick and 6,820,657 to Hedrick, which are each incorporated by reference in their entirety. 
         [0027]    Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the description. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.