Abstract:
A mine roof bolt for use with a cable comprises a barrel having a first end and a second end, the second end having a rounded surface, a bore extending through the barrel between the first end and the second end and including a tapered portion, the bore sized to receive the cable, a pair of wedges sized for placement in the tapered portion of the bore and adapted to frictionally engage a cable disposed in the tapered portion of the bore, a recess defined in the first end of the barrel, and a driving nut sized for insertion in the recess and adapted for engagement by a driving tool.

Description:
RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Application Ser. No. 60/418,875, filed Oct. 16, 2002. 

   FIELD OF THE INVENTION 
   The present invention relates generally to roof bolts used in underground mining operations and, more particularly, to a wedge barrel for a mine roof bolt having a recessed area sized to accept a spinning tool. 
   BACKGROUND OF THE INVENTION 
   In mining operations, bolts are often used to support the roof of the mine. Typically, a hole is drilled into the rock formation that forms the mine roof, and then a mine roof bolt is placed in the hole and secured by a fast-curing resin material or other suitable substance. The roof bolt, which can be formed of wire strands woven or wound together to form a cable, includes a widened bearing plate that bears against a portion of the ceiling, thus holding a portion of the ceiling in place. 
   One approach for installing such bolts is to drill an over-sized hole into the rock and then insert one or more resin cartridges into the hole. The elongated cable portion of the mine roof bolt is then forced into the hole, and rotated. This process ruptures the resin cartridges and mixes the two resin components together within the space between the cable portion of the bolt structure and the over-sized hole. 
   Such roof bolts typically include a wedge barrel. The wedge barrel provides a bearing surface so that the tensile load carried by the elongated cable bolt can be suitably transferred to the bearing plate. The wedge barrel is commonly joined to the cable bolt by a plurality of wedges which are wedged between the cable itself and an inside tapered surface of the wedge barrel prior to installation of the roof bolt. Using a suitable tool, the wedge barrel is spun to rotate the cable within the hole as outlined above. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary cross-sectional view of a mine roof bolt including a wedge barrel assembled in accordance with the teachings of a first disclosed example of the present invention; 
       FIG. 1A  is cross-sectional view taken along line  1 A— 1 A of  FIG. 1 ; 
       FIG. 2  is a fragmentary cross-sectional view of the wedge barrel; 
       FIG. 3  is a top plan view thereof; 
       FIG. 4  is a perspective view of a square nut sized for insertion in the recess of the wedge barrel; 
       FIG. 5  is an enlarged fragmentary cross-sectional view of a wedge barrel assembled in accordance with the teachings of a second disclosed example of the present invention and including a snap-in-place square nut for insertion into the recess of the wedge barrel; 
       FIG. 6  is an enlarged fragmentary view in perspective of a wedge barrel the assembled in accordance with the teachings of another disclosed example of the present invention and illustrating the tail of the cable disposed below the recess; and 
       FIG. 7  is an enlarged fragmentary view in perspective of a recess sized to receive either a square driving nut or a hex-shaped driving nut; 
       FIG. 8  is an enlarged fragmentary plan view illustrating the manner by which a hex-shaped driving nut is received in the recess; and 
       FIG. 9  is an enlarged perspective view of a driving nut having a square portion and a hexagonal portion. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The examples described herein are not intended to be exhaustive or to limit the scope of the invention to the precise form or forms disclosed. Rather, the following exemplary embodiments have been chosen and described in order to best explain the principles of the invention and to enable others skilled in the art to follow the teachings thereof. 
   Referring now to the drawings, a mine roof bolt assembled in accordance with the teachings of a first disclosed example of the present invention is shown therein and is generally referred to by the reference numeral  10 . The mine roof bolt  10  includes a cable  12  ( FIG. 1  only) which is typically formed of a plurality of woven or wound wires  12   a  ( FIG. 1A ) strands as is known to those of skill in the art. The positional terms that are used in the following description, such as “top” and “bottom”, etc., relate to the roof bolt  10  positioned as shown in the drawings. It will be understood that, when the roof bolt  10  is in use, the roof bolt  10  will be inverted from the position shown in  FIG. 1  such that the cable  12  extends upwardly into a bore hole drilled in the ceiling of a mine. The cable  12  includes a first end  14  ( FIG. 1 ) and a second end (not shown but which is disposed within the roof of the mine as would be known). The second end is inserted into the bore hole (not shown) as would be known. 
   The roof bolt  10  also includes a bearing plate  16  (shown only partially in  FIG. 1 ) having an aperture  16   a , and a wedge barrel  18 . The wedge barrel  18  includes a top portion  20 , a bottom portion  22 , an external surface  24 , and an internal bore  26 . The bottom portion  22  of the wedge barrel  18  meets the bearing plate  16  along a generally curved or spherical interface  19  as would be known and which, in a preferred form, serves to compensate for situations when the hole axis and the ceiling of the mine are not perpendicular. It will be understood that the bearing plate spreads out in a direction generally perpendicular relative to the axis of the cable  12  when viewing FIG.  1 . 
   The internal bore  26  has a generally tapered, sloping, or generally conical internal surface  28 , which is shaped to interact with or correspond to a pair of sloped or tapered wedges  30   a ,  30   b  in order to secure the first end  14  of the cable  12  to the wedge barrel  18 . The tapered wedges  30   a ,  30   b  are typically sloped or tapered on their outside surfaces (the surfaces away from the centerline of the bore  26 ) and typically include threads  30   c  on their inside surfaces (the surfaces facing and abutting the cable  12 ). The internal surfaces, which are preferably hardened, are forced into engagement with the cable  12  in a known manner in order to bite and grip the cable when the wedges  30   a ,  30   b  are forced further into the tapered bore  26  (i.e., downward when viewing FIG.  1 ). 
   The internal bore  26  includes an upper portion  32  which is shaped to form a recess  34 . In the example of  FIGS. 1-5 , the recess is generally square. Other suitable shapes may be employed. The recess  34  includes a floor  36  ( FIGS. 1-3 ) defined by, in the disclosed example, four sections  36   a ,  36   b ,  36   c , and  36   d  (FIG.  3 ). Preferably, the floor  36  is spaced downward from the top portion  20  of the wedge barrel  18  so as to leave a gap  38  between the floor  36  and an upper end  40   a ,  40   b , of the wedges  30   a ,  30   b , respectively. The recess  34  includes four internal sidewalls  42   a ,  42   b ,  42   c  and  42   d  (FIG.  3 ). 
   The roof bolt  10  may be provided with a nut  44  ( FIGS. 1 ,  4  and  5 ) having a central bore  46  sized to accommodate a portion of the cable  12 . According to the disclosed example, the nut  44  has a generally square shape when viewed in plan in order to complement the generally square shape of the recess  34 . Again, other suitable shapes may be employed. It will be understood that, should the shape of the recess  34  be altered, then the shape of the nut  44  may also be altered in order to complement the shape of the recess  34  such that the nut  44  will suitably fit into the recess  34 . The nut  44  includes four sidewalls  44   a ,  44   b ,  44   c , and  44   d  (FIG.  4 ). In accordance with the disclosed example, the nut  44  is sized to measure approximately 1.125 inches by 1.125 inches when viewed in plan, which matches the size of many readily available driving tools/sockets. The recess  34  is thus suitably sized to receive the nut  44  of this relatively standard size. Also, according to the disclosed example, the height H of the nut  44  is preferably sized so that the nut  44  includes a protruding portion  47  when suitably placed in the recess  34 . In the disclosed example, the protruding portion  47  measures about 0.5 inches. 
   Preferably, the wedge barrel  18  is formed of cast or forged steel. As is known, the wedges  30   a ,  30   b , which are preferably formed of hardened steel, include teeth that bite into the cable  12 . The outer surface  24  of the wedge barrel  18  is preferably round when viewed in plan (FIG.  3 ). Further, as alluded to above, the bottom  22  of the wedge barrel  18  is formed in a generally spherical dome shape where it interfaces with the bearing plate  16 . 
   A mine roof bolt  10  assembled in accordance with the disclosed example may offer one or more functional advantages. For example, when the recess  34  and the nut  44  are sized as outlined above, only a standard 1⅛″ square socket tool, which is readily available in underground mining operations, is required to spin the cable bolt  10  into the resin material. No extra tool is required to install the mine roof bolt  10 . Also, the square pattern of the recess  34  is part of the wedge barrel casting, and thus the square recess cannot break off during spinning of the roof bolt  10 . Moreover, due to the fact that the end  14  of the cable  12  is recessed within the wedge barrel  18  in or below the recess  34  and/or below the nut  44 , the risk of injury may be reduced. 
   In use, a miner can easily make a tool by welding a square piece to a standard socket. The cost for such a tool may be insignificant, and the miner may make as many tools as required. The wedge barrel  18  also may be delivered with a square recess only, absent the nut  44 . 
   Alternatively, the miner may request that the roof bolt  10  be supplied with the nut  44  already in place within the recess  34  in accordance with a second disclosed example of the present invention. Referring to  FIG. 5 , the recess  34  may be provided with one or more barbs  48  which are sized to engage a corresponding protrusion or ledge  50  provided adjacent a lower portion of the nut  44 . The nut  44  may be formed from a suitable molded plastic or from a steel or cast material. In such a case, the miner does not need to produce or fabricate any drive tool other than a standard and readily available socket. 
   The nut  44  is sized to be taller than the recess  34 , such that a portion of the nut  44  (see for example,  FIG. 5 ) extends out of the recess and beyond the top portion  20  of the wedge barrel  18 . Thus, a sufficient portion is exposed to permit the nut to be engaged by a suitable driving tool, such as an impact wrench or other power drill/tool of the type known to those of skill in the art and commonly employed in mining operations. 
   Referring now to  FIG. 6 , it can be seen that an upper end  52  of the cable  12  may be sized so as to terminate before the upper end  52  of the cable  12  extends into the recess  34 . Thus, in accordance with the disclosed example, there may be little or no contact between the nut  44  (for example, the nut  44  shown in  FIGS. 1 ,  4  or  5 , or the nut  44 - 1  of FIG.  8 ), and the upper and  52  of the cable  12 . 
   Referring now to  FIGS. 7 and 8 , the recess  34  shown therein is slightly modified to include a first set of surfaces  54  and a second set of surfaces  56 . More specifically, the surfaces  54   a ,  54   b ,  54   c , and  54   d  are sized to receive a square driving nut the second set of surfaces  56 , in the disclosed example, may take the form of pointed grooves  56   a ,  56   b ,  56   c  and  56   d  formed in each of the surfaces  54   a ,  54   b ,  54   c  and  54   d , respectively. Thus, a square nut  44 , such as the nut discussed above with respect to the earlier disclosed example(s), will engage the surfaces  54   a - 54   d  of the recess  34 . Similarly, a hex-shaped nut  44 - 1  disposed in the recess  34  will engage, for example, two of the grooves  56   a - 56   d  and two of the surfaces  54   a - 54   d . Accordingly, the recess  34  will receive either the square nut  44  or the hex-shaped nut  44 - 1 . 
   In accordance with one or more of the examples disclosed herein, one or more advantages may be realized. For example, a miner (not shown) can easily make a suitable driving tool by welding a square piece to a standard socket (typically a 1⅛ inch socket). The cost for fabricating such a tool is insignificant, and thus the miner can make as many tools as required. Further, the wedge barrel may be delivered with a suitable nut (either a square or hexagonal nut) as outlined above. Further, it will be appreciated that the wedge barrel may be cast, and the nut may be formed of a suitable metal or from a suitable high impact plastic material. 
   Referring now to  FIG. 9 , a nut  144  is shown which may be adaptable for use with either of the embodiments discussed above. The nut  144  includes a hexagonal end  146  and a square end  148 . It will be appreciated that the hexagonal end  146  of the nut  144  may be inserted into the hexagonal recess of  FIGS. 6-8  and may be driven by a square driver (not shown) suitably engaging the square end  148 . Similarly, the square end  148  of the nut  144  may be inserted into the square recess of  FIGS. 1-5  and may be driven by a hexagonal driver (not shown) suitably engaging the hexagonal end  146 . 
   It will be appreciated that details of the various embodiments discussed herein are not intended to be mutually exclusive. Thus, various aspects and details of the disclosed examples may be interchanged. Also, it will be appreciated that the recess  34  and the nut  44  may take a variety of complementary forms, such as oval-shaped, star-shaped, etc. 
   Numerous additional modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. This description is to be construed as illustrative only, and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and method may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.