Abstract:
A method of producing a mine roof bolt includes: providing a plurality of bars of a predetermined length, moving the plurality of bars along a conveyor and indexing the position of the plurality of bars, and passing a portion of each of the bars through a processing station, where the processing station comprises at least one of a header assembly, an extruder assembly, and a threading assembly. The method further includes processing a portion of each of the bars with the processing station. A system for producing a mine roof bolt includes a conveyor configured to index and transport a bar, a feed arrangement configured to continuously deliver bars to the conveyor, a processing station comprising at least one of a header assembly, an extruding assembly, and a threading assembly, where the processing station is positioned along the conveyor and configured to receive and process a portion of the bars.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/776,010, filed Mar. 11, 2013, the entire content of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    Description of Related Art 
         [0003]    Mine roof bolts are used to reinforce unsupported rock formations adjacent to a mine opening. In particular, the roof of a mine is conventionally supported by tensioning the roof with steel bolts inserted into bore holes drilled in the mine roof that reinforce the unsupported rock formation above the mine roof. The mine roof bolt may be anchored mechanically to the rock formation by engagement of an expansion assembly on the distal end of the mine roof bolt with the rock formation. Alternatively, the mine roof bolt may be adhesively bonded to the rock formation with a resin bonding material inserted into the bore hole. A combination of mechanical anchoring and resin bonding may also be employed by using both an expansion assembly and resin bonding material. 
         [0004]    A mechanically anchored mine roof bolt typically includes an expansion assembly threaded onto a distal threaded end of the bolt shaft and a drive head for rotating the bolt. A mine roof plate is positioned between the drive head and the mine roof surface. The expansion assembly generally includes a multi-prong shell supported by a threaded ring and a plug threaded onto the end of the bolt. When the prongs of the shell engage with rock surrounding a bore hole, and the bolt is rotated about its longitudinal axis, the plug threads downwardly on the shaft to expand the shell into tight engagement with the rock thereby placing the bolt in tension between the expansion assembly and the mine roof surface. 
         [0005]    When resin bonding material is utilized, the bonding material penetrates the surrounding rock formation to adhesively join the rock strata and to firmly hold the roof bolt within the bore hole. Resin is typically inserted into the mine roof bore hole in the form of a two component plastic cartridge having one component containing a curable resin composition and another component containing a curing agent (catalyst). The two component resin cartridge is inserted into the blind end of the bore hole and the mine roof bolt is inserted into the bore hole such that the end of the mine roof bolt ruptures the two component resin cartridge. Upon rotation of the mine roof bolt about its longitudinal axis, the compartments within the resin cartridge are shredded and the components are mixed. The resin mixture fills the annular area between the bore hole wall and the shaft of the mine roof bolt. The mixed resin cures and binds the mine roof bolt to the surrounding rock. The mine roof bolt is typically rotated via a drive head. With bolts that are point anchored and tensioned, a breakaway nut may be used to rotate the bolt and subsequently tension the bolt upon curing of the resin bonding material. 
       SUMMARY OF THE INVENTION 
       [0006]    In one embodiment, a method of producing a mine roof bolt includes providing a plurality of bars of a predetermined length, moving the plurality of bars along a conveyor and indexing the position of the plurality of bars, and passing a portion of each of the plurality of bars through a processing station, where the processing station comprises at least one of a header assembly, an extruder assembly, and a threading assembly. The method further includes processing a portion of each of the plurality of bars with the processing station. 
         [0007]    The method may further include where a longitudinal and lateral position of the plurality of bars is indexed. The processing station may include a header assembly, and processing the portion of each of the plurality of bars may include: heating a portion of a first bar of the plurality of bars; passing the portion of the first bar through the header assembly; and forging a head at an end of the first bar. The method may further include actuating clamping assemblies to fix the position of the first bar during forging. The processing station may include an extruder assembly, and processing the portion of each of the plurality of bars may include: passing a portion of a first bar of the plurality of bars through the extruder assembly; actuating a die cylinder to move a die holder assembly toward the first bar; and extruding a portion of the first bar. The method may include, after extruding the portion of the first bar, moving the first bar along the conveyor toward a second extruder assembly, passing the portion of the first bar of the plurality of bars through the second extruder assembly, actuating a die cylinder to move a die holder assembly toward the first bar, and further extruding the portion of the first bar. The method may include moving each of the plurality of bars from a feed rack to the conveyor using a feed delivery device. The movement of the conveyor and the feed delivery device may be synchronized. The method may include, after processing the portion of the bar, continuing to move the bar along the conveyor and depositing each of the plurality of bars into a receptacle. 
         [0008]    In a further embodiment, a system for producing a mine roof bolt includes a conveyor configured to index and transport a bar, a feed arrangement configured to continuously deliver bars to the conveyor, a processing station comprising at least one of a header assembly, an extruding assembly, and a threading assembly. The processing station is positioned along the conveyor and configured to receive and process a portion of the bars. 
         [0009]    The feed arrangement may include a feed rack and a feed wheel positioned adjacent to the feed rack with the feed wheel configured to receive bars from the feed rack and to deliver the bars to the conveyor. The conveyor may include a drive member and at least two drive sprockets with the drive member forming a continuous loop and extending circumferentially around the at least two drive sprockets. The drive member may include a plurality of indexing clamps with the plurality of indexing clamps configured to receive the bars and index a lateral position of the bars relative to adjacent bars. The system may further include a heating source configured to heat a portion of the bar and the processing station may be a header assembly. The header assembly may include a frame assembly, upper and lower clamp assemblies, and at least one header die assembly with the upper and lower clamp assemblies configured to engage a portion of the bar. The at least one header die assembly may include a die cylinder, a die holder, and a tool received by the die holder with the die holder moveable between a retracted and extended position via the die cylinder. The header assembly is configured to form a head at an end of the bar. The processing station may be an extruder assembly with the extruder assembly including a frame assembly, upper and lower clamp assemblies, and at least one extruder die assembly. The upper and lower clamp assemblies are configured to engage a portion of the bar. The at least one extruder die assembly may include a die cylinder, a die holder, and a tool received by the die holder with the die holder moveable between a retracted and extended position via the die cylinder. The extruder assembly is configured to extrude a portion of the bar. 
         [0010]    The processing station may be a threading assembly that includes a frame assembly, a moving die assembly, and a stationary die assembly with the moving die assembly movable relative to the frame assembly and the stationary die assembly via a threading die cylinder. The moving die assembly and the stationary die assembly are configured to form threads on a portion of the rod. The threading assembly may further include a support stand having first and second paddles with the first and second paddles each configured to initially support the rod prior to forming threads on a portion of the rod. The first and second paddles are movable in a downward direction. The system may further include an index cylinder and a stop plate that are configured to index the longitudinal position of a bar positioned on the conveyor with the index cylinder moveable between first and second positions and configured to move a bar until the bar contacts the stop plate. The system may further include a receptacle positioned adjacent to an end of the conveyor with the plurality of indexing clamps configured to release the bars and deposit the bars into the receptacle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a top schematic view of a system and method of producing a mine roof bolt according to one embodiment of the present invention. 
           [0012]      FIG. 2A  is a front view of a conventional mine roof bolt. 
           [0013]      FIG. 2B  is a bottom view of the mine roof bolt shown in  FIG. 2A . 
           [0014]      FIG. 3  is a front perspective view of an extruder assembly according to one embodiment of the present invention. 
           [0015]      FIG. 4  is a rear perspective view of the extruder assembly shown in  FIG. 3 . 
           [0016]      FIG. 5  is a front view of the extruder assembly shown in  FIG. 3 . 
           [0017]      FIG. 6  is a top view of the extruder assembly shown in  FIG. 3 . 
           [0018]      FIG. 7  is a partial rear perspective view of the extruder assembly shown in  FIG. 3 . 
           [0019]      FIG. 8  is a partial right side view of the extruder assembly shown in  FIG. 3 . 
           [0020]      FIG. 9  is a cross-sectional view of the extruder assembly shown in  FIG. 3 . 
           [0021]      FIG. 10  is an exploded perspective view of an extruder die holder assembly according to one embodiment of the present application. 
           [0022]      FIG. 11  is cross-sectional view of the extruder die holder assembly shown in  FIG. 10 . 
           [0023]      FIG. 12  is a perspective view of a header assembly according to one embodiment of the present invention. 
           [0024]      FIG. 13  is a rear perspective view of the header assembly shown in  FIG. 12 . 
           [0025]      FIG. 14  is an exploded perspective view of a header die assembly according to one embodiment of the present invention. 
           [0026]      FIG. 15  is a right perspective view of a threading assembly according to one embodiment of present invention. 
           [0027]      FIG. 16  is a left perspective view of the threading assembly shown in  FIG. 15 . 
           [0028]      FIG. 17  is a top view of the threading assembly shown in  FIG. 15 . 
           [0029]      FIG. 18  is a right rear perspective view of the threading assembly according to one embodiment of the present invention. 
           [0030]      FIG. 19  is a front schematic view of a feed and indexing assembly according to one embodiment of the present invention. 
           [0031]      FIG. 20  is a top schematic view of the feed and indexing assembly shown in  FIG. 19 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    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. 
         [0033]    Referring to  FIG. 1 , one embodiment of a system  10  for producing a mine roof bolt includes a conveyor  12 , a heating source  14 , a processing station  16 , and a cradle or receptacle  18  for receiving finishing product. Raw bars  20 , such as rebar, are fed to a first end of the conveyor  12 . The bars  20  may be placed in a holding rack and picked up through a bar separator that will index and position the bars  20  on the conveyor  12 . The bars  20  are fed into the heating source  14 , such as an induction heating coil, and a predetermined portion of each bar  20  is heated to an appropriate forging temperature. The bars  20  are then indexed along the conveyor  12  and moved to the processing station  16  for further processing. One embodiment of the feed and indexing assembly, which provides bars  20  from a holding rack and indexes the position of the bars  20 , is discussed in more detail below and shown in  FIGS. 19 and 20 . The processing station  16  may be a hydraulic forging assembly that forms a head on an end of the bar  20 , which is discussed in more detail below. After being processed at the processing station  16 , the bars  20  are moved to a discharge position that will deposit the finished bars in the cradle  18  for collection and movement to further processing. Such further processing may include extrusion and/or threading processes, which are also discussed in more detail below. Further, although  FIG. 1  only shows a single processing station  16 , the system  10  may include one or more processing stations  16  that are automated to allow raw bar material to be fed and indexed on the conveyer  12  and processed by the one or more processing stations  16  to provide a finished mine roof bolt. 
         [0034]    Referring to  FIGS. 2A and 2B , the system  10  shown in  FIG. 1  may be utilized to produce a mine roof bolt  26  having a head  28  formed on a first end  30  that is positioned opposite from a second end  32 . The head  28  includes a flange  34  and a four-sided square-shaped protrusion  36  that is configured to engage a drive tool, although the system may be used to form other types of head configurations. The mine roof bolt  26  may also be further processed by extruding the second end  32  and/or threading the second end  32  of the mine roof bolt  26 . The threaded second end (not shown) may be used to receive an expansion assembly (not shown) as noted in the background section above. Rather than providing an integral head on the first end  30  of the mine roof bolt  26 , the first end  30  of the mine roof bolt  26  may be extruded and threaded so that the first end  30  can receive a nut (not shown) or other suitable tensioning arrangement. 
         [0035]    Referring to  FIGS. 3-11 , one embodiment of the processing station  16  includes an extruder assembly  40 . The extruder assembly  40  performs a cold extrusion process and does not require the heating source  14  shown in  FIG. 1 , although the extruder assembly  40  may also be utilized in hot extrusion process where the heating source  14  is needed. The extruder assembly  40  is used to extrude the first and/or second ends  30 ,  32  of the mine roof bolt  26  to form a smooth surface. The extruder assembly  40  includes a frame assembly  42  and first, second, and third extruder die assemblies  44 ,  46 ,  48 . The frame assembly  42  includes four spaced apart frame plates  52  that are secured together. Each frame plate  52  is generally square-shaped and defines first and second openings  54 ,  56 . The frame plates  52  are secured to each other with a frame support plate  58  that is received by the first opening  54  of each frame plate  52  with the frame support plate  58  extending perpendicularly between the frame plates  52 . The frame support plate  58  is secured to the frame plates  52  with angle brackets  60 . The frame plates  52  are also secured to each other via first and second grip plates  62 ,  64 . The second opening  56  of each frame plate  52  is configured to allow mine roof bolts  26  to be received by the extruder assembly  40 . Further, as shown more clearly in  FIG. 7 , a plurality of spacer plates  66  is positioned between adjacent frame plates  52 . 
         [0036]    Referring still to  FIGS. 3-11 , the extruder die assemblies  44 ,  46 ,  48  each include a die cylinder  68 , a die holder assembly  70 , and upper and lower clamping assemblies  72 ,  74 . The die cylinders  68  and die holder assemblies  70  are each supported by respective die support plates  76  that are received by the frame support plates  58  and generally extend parallel to the frame plates  52 . Each die cylinder  68  includes a die cylinder rod  78  that is secured to the respective die holder assemblies  70 . The die cylinder rod  78  can be actuated between a retracted and fully extended position with corresponding movement of the respective die holder assembly  70 . The die cylinder  68  is a hydraulic cylinder, although other suitable arrangements for displacing the die holder assembly  70  may be utilized. Each of the upper clamping assemblies  72  includes an upper cylinder  80  and an upper grip  82  secured to the upper cylinder  80  via an upper cylinder rod  84 . Each of the lower clamping assemblies  74  includes a lower cylinder  86  and a lower grip  88  secured to the lower cylinder  86  via a lower cylinder rod  90 . The upper and lower cylinders  80 ,  86  can be actuated to move the upper and lower grips  82 ,  88  between a spaced position and a clamping position. In particular, the upper and lower cylinders  80 ,  86  are configured to be actuated to apply a clamping force to the mine roof bolt  26  to securely hold the mine roof bolt  26  while being processed. 
         [0037]    Referring to  FIGS. 8-11 , each of the die holder assemblies  70  includes a body  92 , an insert holder  94  and insert  96  received within the body  92 , and a cover plate  98 . The body  92  defines an internal passageway  100  having a first end  102  for receiving an end of the die cylinder rod  78  and a second end  104  for receiving the insert holder  94  and insert  96 . Each of the die holder assemblies  70  further includes a pair of side rollers  106  and an upper roller  108 . The pair of side rollers  106  is received by respective spaced apart lower tracks  110  positioned on the die support plates  76 . The upper roller  108  of each die holder assembly  70  is received by a respective upper track  112  positioned on a track support plate  114  that extends perpendicularly to the frame plates  52 . The pair of side rollers  106  and the upper roller  108  allows each die holder assembly  70  to be supported and to be freely moveable between a retracted and extended position while extruding or processing the mine roof bolt  26 . 
         [0038]    Referring again to  FIGS. 1-11 , when the bar  20  or mine roof bolt  26  reaches the extruder assembly  40  and is in a proper position, the upper and lower clamping assemblies  72 ,  74  are automatically actuated to hold the bar  20  securely during the extrusion process. The lower cylinder  86  is actuated to extend the lower cylinder rod  90  to full stroke to maintain constant a constant vertical or centerline of the bar  20  being extruded. The upper cylinder  80  provides a clamping force which is regulated via a pressure reduction to the upper cylinder  80 . Once clamping is completed, the die cylinder  68  is actuated to move one of the die holder assemblies  70  towards the bar  20 . The insert  96  of the die holder assembly  70  engages the bar  20  and completes a first step of the extrusion process. The die cylinder  68  will then retract and the upper and lower clamping cylinders  80 ,  86  will retract to remove the clamping force applied by the upper and lower grips  82 ,  88 . The bar  20  is then moved to the next extruder die assembly  44 ,  46 ,  48  for further processing. The extruder assembly  40  includes three extruder die assemblies  44 ,  46 ,  48  to progressively provide the final dimensioning and processing of the bar  20 . The extruder assembly  40 , however, may include one or more extruder die assemblies. After finishing the extrusion process, the bars  20  or mine roof bolts  26  are moved to the discharge position and deposited into the cradle  18  for collection and/or further processing. 
         [0039]    Referring to  FIGS. 12-14 , a further embodiment of the processing station  16  includes a header assembly  120 . The header assembly  120  is configured to form the head  28 , as described above, on the bar  20  or mine roof bolt  26 . The header assembly  120  is embodied as a forging mechanism, although other suitable arrangements may be provided to form the head  28 . As discussed above, the mine roof bolt  26  is heated by the heating source  14  shown in  FIG. 1  before reaching the header assembly  120 . The header assembly  120  may be similar to the extruder assembly  40  discussed above and shown  FIGS. 3-11 . Although not shown, the header assembly  120  would also include the die cylinder  68  and upper and lower clamping assemblies  72 ,  74 . The header assembly  120  also includes frame plates  122  that are different from the frame plates  52  of the extruder assembly  40 , although the header assembly  120  may also utilize the same components of the extruder assembly  40  with different tooling being utilized. In particular, the frame plates  122  of the header assembly  120  are each formed with separate upper and lower portions  124 ,  126  that are secured to each other and to adjacent frame plates  122 . Further, the frame plates  122  define a single opening  128  and are each configured to receive bars  20  or mine roof bolts  26  for the forging process. As shown more clearly in  FIG. 14 , the header assembly  120  includes first and second cone assemblies  130 ,  132  and an insert assembly  134  rather than the extruder die assemblies  44 ,  46 ,  48  of the extruder assembly  40 . Each cone assembly  130 ,  132  includes a body  136  that receives a cone tool  138 . Although shown in front of the cone tool  138 , a tool spacer  140  and washer  142  are positioned behind the cone tool  138  with a cover plate  144  secured to the body  136  to fix the cone tool  138  within the body  136 . Each cone assembly  130 ,  132  is actuated between an extended position and a retracted position in the same manner as discussed above in connection with the extrude die assemblies  44 ,  46 ,  48  of the extruder assembly  40 . 
         [0040]    Referring again to  FIGS. 12-14 , the insert assembly  134  includes a body  146  that receives an insert back plate  148 , an insert holder  150 , and an insert  152 . The insert  152  is configured to form the final dimensions of the square-shaped protrusion  36  of the head  28  shown in  FIGS. 2A and 2B , although other inserts  152  may be utilized to form a variety of head shapes and sizes. The body  146  further receives a stencil holder  154 , a stencil back plate  156 , and a stencil  158 . The stencil  158  is configured to provide product identification or other information on the head  28  of the mine roof bolt  26 . A pair of clamps  160  is used to secure the insert  152 , stencil  158 , and other components within the body  146  of the insert assembly  134 . The bars  20  or mine roof bolts  26  may be fed through the header assembly  120  in the same manner as discussed above in connection with the extruder assembly  40 . The head  28  of the mine roof bolt  26  may be formed by first and second forging processes performed by the first and second cone assemblies  130 ,  132  to progressively form a cone shape on an end of the bar  20  and a third forging process performed by the insert assembly  134  to provide the final shape and dimension of the head  28  shown in  FIGS. 2A and 2B . The header assembly  120 , however, may include one or more forging processes to provide the final head shape and size. 
         [0041]    Referring to  FIGS. 15-18 , another embodiment of the processing station  16  includes a threading assembly  162 . The threading assembly  162  is configured to thread a portion of the mine roof bolt  26 , such as an end of the mine roof bolt  26 . The threading machine  162  generally includes a frame assembly  164 , a moving die assembly  166 , and a stationary die assembly  168 . The frame assembly  164  includes three frame plates  170  secured to a base plate  172 , a back plate  174 , and a front plate  176 . The front plate  176  defines an opening  178  that is configured to receive a portion of the mine roof bolt  26 . The frame assembly  164  also includes removable gusset plates  180  and a gusset base plate  182 . The moving die assembly  166  is movable relative to the frame assembly  164  and the stationary die assembly  168  via a die cylinder  184 . The die cylinder  184  may be a hydraulic cylinder, although other suitable arrangements for moving the moving die assembly  166  may be utilized. The moving die assembly  166  includes a moving die block  186  and a moving die  188  that is received by the moving die block  186 . The moving die block  186  and moving die  188  are moved vertically between a retracted position and an extended position along a track formed by a frame track  190  secured to the back plate  174  and a die track  192  secured to the moving die block  186 . The stationary die assembly  168  is fixed relative to the frame assembly  164  and includes a stationary die block  194  and a stationary die  196  received by the stationary die block  194 . 
         [0042]    Referring again to  FIGS. 15-18 , the threading assembly  162  also includes a support stand  198  having first and second paddles  202 ,  204  that are each configured to receive the mine roof bolt  26  for positioning the mine roof bolt  26  between the moving and stationary dies  188 ,  196 . The first and second paddles  202 ,  204  are also configured to pivot downwardly when engaged and return to their original position. The first and second paddles  202 ,  204  may include a spring mechanism (not shown) to return the paddles  202 ,  204  to their original position after pivoting downward. The threading assembly  162  includes a pusher member  206  that is moveable between a retracted and extended position by a pusher cylinder  208 . The pusher member  206  is moved to the extended position and is configured to engage a mine roof bolt  26  positioned on the first and second paddles  202 ,  204 . The pusher member  206  further causes the paddles  202 ,  204  to pivot downward and ensures that the mine roof bolt  26  is positioned between the moving and stationary dies  188 ,  196  once the threading operation is commenced. The threading assembly  162  is configured to receive the mine roof bolt  26  between the stationary die  196  and the moving die  188  and moving the moving die  188  to roll the mine roof bolt  26  and form threads on a portion of the mine roof bolt  26 . The end of the mine roof bolt  26  to be threaded may be fed through the opening  178  in the front plate  176  and supported by the paddles  202 ,  204  of the support stand  198 . 
         [0043]    Referring still to  FIGS. 15-18 , the mine roof bolt  26  is rolled between the moving die  188  and the stationary die  196  to form threads on a portion of the mine roof bolt  26  and is deposited onto the base plate  172  at the bottom of the threading assembly  162 . The gusset plates  180  are configured to support the threading assembly  162  as a stand alone unit. However, the gusset plates  180  may be removed and the threading assembly  162  can be secured attached to one of the other processing stations  40 ,  120 . In particular, the front plate  176  of the threading assembly  162  can be secured attached to one of the frame plates  52  of the extruder assembly  40  to provide continuous throughput of the mine roof bolts  26 . After being threaded, the mine roof bolts  26  may be carried by a conveyor arrangement (not shown) from the threading machine to a packaging area or further processing area. 
         [0044]    Referring to  FIGS. 19 and 20 , one embodiment of a feed and indexing assembly  212  includes a feed rack  214 , a feed wheel  216 , a drive member  218 , drive sprockets  220 , and indexing clamps  222 . The feed rack  214  is configured to provide a continuous feed of bars  20  to the feed wheel  216 . The feed wheel  216  is generally disc-shaped and includes a plurality of notches  224  that are configured to receive the bars  20 . The feed wheel  216  continuously rotates and receives bars  20  in the notches  224 , which are fed from the feed rack  214 . The feed wheel  216  feeds the bars  20  to the conveyor  12  shown in  FIG. 1 . The conveyor  12  is embodied as the drive member  218  mounted on the drive sprockets  220 . The drive member  218  may be a drive chain, although other suitable arrangements may be utilized for the drive member  218 . A plurality of drive members  218  and a plurality of drive sprockets  220  may be utilized to support the bars  20  or mine roof bolts  26  at each end. The drive sprockets  220  are driven and rotated to move the bars  20  or mine roof bolts  26  along the conveyer  12  and through the various processing stations  16 . The drive sprockets  220  may be driven via an electric motor, although other suitable arrangements may be utilized to drive the drive sprockets  220 . The drive member  218  may include a plurality of sets of indexing clamps  222  that receive the bars  20  from the feed wheel  216  and position the bars  20  a predetermined lateral distance apart from each other. The indexing clamps  222  are secured to the drive member  218  and are configured to be spaced apart as they rotate about the drive sprockets  220 . In particular, as shown in  FIG. 19 , the indexing clamps  222  separate as they rotate around the drive sprocket  220  and receive the bar  20  from the feed wheel  216 . As the indexing clamps  222  move beyond the drive sprocket  220 , the indexing clamps  222  are moved back together to receive and index the bars  20 . 
         [0045]    Referring to  FIG. 20 , the feed and indexing assembly  212  further includes an index cylinder  226  and a stop plate  228  that are configured to index the longitudinal position of the bars  20  or mine roof bolts  26 . The index cylinder  226  includes an engagement  230  that is moveable between first and second positions and is configured to engage the bars  20  and move them in a longitudinal direction. In particular, the bars  20  are engaged by the engagement  230  of the index cylinder  226  until the bars  20  abut the stop plate  228  to ensure that the bars  20  have a proper longitudinal orientation before entering the processing stations  16 . 
         [0046]    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.