Abstract:
A degradation pick or holder shank for facilitating installation, retention and removal is disclosed. The shank may comprise an axially compressive portion that may contract radially when stretched axially and then expand again radially when released. An installation tool may be used to stretch the shank axially during insertion into a bore and then release the shank to retain it within the bore.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/240,932, filed Oct. 13, 2015, the disclosure of which is incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Degradation picks are known to be used in such fields as road milling, mining, and trenching to engage and degrade tough materials such as asphalt, concrete, and rock. In use, such degradation picks may be secured to an exterior of a rotatable drum or continuous chain so as to be repeatedly brought into contact with a surface of a material to be degraded. 
         [0003]    Degradation picks are known to take several forms. One form of degradation pick, as described in U.S. Pat. No. 7,396,086 to Hall, et al., comprises a shank attached to a base of a steel body. A cemented metal carbide core with an impact tip comprising a diamond material may be press fit into the steel body opposite the shank. The shank may be secured within a holder or block attached to a milling drum leaving the impact tip exposed. 
         [0004]    Such degradation picks and holders may dislodge from their respective bore holes due to the repeated impact forces experienced while in use. Also, it is often necessary to replace degradation picks as they wear which can be a dangerous, time consuming and expensive process. Consequently, efforts have been made to provide more secure connections between degradation pick and holder shanks and bore holes that may also allow for quick removal and replacement. 
         [0005]    For example, U.S. Pat. Pub. No. 2011/0254349 to Hall et al., describes a pick assembly comprising a pick shank configured to be press fit in a bore within a block. The shank comprises at least one longitudinal recess extending along the shank from a distal end of the shank. The recess allows the shank to resiliently collapse upon insertion into the bore while maintaining a press fit between the bore and the shank. 
         [0006]    Despite these advancements in the art, designs such as these comprising uneven perimeter thicknesses may lead to uneven stresses and thus premature failure. Thus, improvements allowing for more secure connections between degradation pick or holder shanks and bore holes that also allow for quick removal and replacement and even perimeter thicknesses are desired. 
       SUMMARY 
       [0007]    A degradation pick or holder shank for facilitating installation, retention and removal is disclosed. The shank may comprise an axially compressive portion that may contract radially when stretched axially and then expand again radially when released. An installation tool may be used to stretch the shank axially during insertion into a bore and then release the shank to retain it within the bore. 
         [0008]    Such a shank may comprise at least one compliant region comprising an axially-variable cross section. The axially-variable cross section may comprise a bellows shape, an accordion shape, or other shapes to facilitate compliance. To form such a compliant region, a machining tool may be inserted to machine crevices into an interior of a shank. 
         [0009]    A shank of a degradation pick or holder may be inserted into a bore disposed within a holder or block wherein an installation tool may pull a distal end of the shank further into the bore. Pulling the distal end further into the bore may cause axial expansion within the shank and radial contraction within the compliant region. When the installation tool is withdrawn, the compliant region may expand radially to secure the shank within the bore. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates an embodiment of a formation degradation machine. 
           [0011]      FIG. 2  illustrates a rotatable drum. 
           [0012]      FIGS. 3 a -3 b    illustrate a degradation pick, according to an embodiment of the invention. 
           [0013]      FIG. 4 a -4 b    illustrate a holder, according to an embodiment of the invention. 
           [0014]      FIG. 5 a -5 b    illustrate a perspective cross-sectional view of an embodiment of a holder. 
           [0015]      FIG. 6 a - d    illustrates a perspective cross-sectional views of embodiments of a holder. 
           [0016]      FIG. 7  illustrates a perspective cross-sectional views of embodiments of a holder. 
           [0017]      FIG. 8  illustrates a perspective cross-sectional views of embodiments of a holder. 
           [0018]      FIG. 9  illustrates a perspective partially cross-sectional view of another embodiment of a holder. 
           [0019]      FIG. 10  illustrates a perspective cross-sectional view of embodiments of a portion of a holder. 
           [0020]      FIG. 11 a -11 b    illustrates a perspective cross-sectional views of embodiments of a compliant region. 
           [0021]      FIG. 12 a - c    illustrates a perspective cross-sectional views of various embodiments of installation tools. 
           [0022]      FIG. 13  illustrates a perspective cross-sectional view of an embodiment of a pick. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    In the following detailed description, only certain example embodiments of the disclosed subject matter are shown and described, by way of illustration. As those skilled in the art would recognize, the disclosed subject matter may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Also, in the context of the present application, when a first element is referred to as being “on” a second element, it can be directly on the second element or be indirectly on the second element with one or more intervening elements interposed therebetween. 
         [0024]      FIG. 1  shows an embodiment of a formation degradation machine  1000  comprising a plurality of degradation picks  1100  secured to an exterior of a rotatable drum  1200 . Rotation of the rotatable drum  1200  by the formation degradation machine  1000  may bring the degradation picks  1100  repeadedly into contact with a surface of a material  1300 . This repeated engagement of the degradation picks  1100  to the material  1300  may degrade the material  1300  causing it to break up into aggregate  1301 . In the present embodiment, the formation degradation machine  1000  is located in an underground mine and the material  1300  to be degraded, coal for example, is contained in a wall of the mine. Once a portion of the material  1300  is degraded into aggregate  1301  it may be captured by a conveyor  1001  and removed for processing. While the embodiment shown depicts a rotatable drum  1200  on a formation degradation machine as part of a mining operation, it should be understood that the present invention may also be used in conjunction with rotatable drums or continuous chains being used in mining, road milling, trenching or other operations where it is desirable to degrade tough materials such as asphalt, concrete or rock. 
         [0025]      FIG. 2  shows an embodiment of a rotatable drum  2200  as seen by a material to be degraded. A plurality of blocks  2201  may be disposed around an exterior of the rotatable drum  2200 . Each of the blocks  2201  may have a bore disposed therein to receive a shaft  2101  from each of a plurality of degradation picks  2100 . Rotation of the rotatable drum  2200  may cause the degradation picks  2100  to engage and degrade a material. The blocks  2201  may be positioned around the exterior of the rotatable drum  2200  to optimize degradation and/or transport aggregate away from the material being degraded. 
         [0026]      FIG. 3 a    shows a perspective view of an embodiment of a degradation pick  3100   a  and a pick block  3201   a.  The degradation pick may comprise a shank  3101   a  that may be inserted into a bore  3202   a  of the pick block  3201   a.    
         [0027]      FIG. 3 b    shows a perspective view of an embodiment of a degradation pick  3100   b,  a holder  3400   b,  and a pick block  3201   b.  The pick block  3201   b  may comprise a bore  3202   b  for receiving a shaft  3401   b  of the holder  3400   b.  The holder  3400   b  may comprise a hole  3402   b  for receiving a shank  3101   b  of the degradation pick  3100   b.  Different holders may comprise bores of various diameters so as to accommodate degradation picks of various sizes to attach to a degradation drum (shown in  FIG. 1 ). 
         [0028]      FIG. 4 a    discloses a perspective view of an embodiment of a holder  100   a.  The holder  100   a  may comprise a body  101   a  attached to a shank  111   a.  The shank  111   a  may comprise a compliant region  110   a  with an axially-variable cross section. In the embodiment shown, the compliant region  110   a  comprises a bellows shape. When the shank  111   a  is urged into a bore (as shown in  FIG. 3 b   ) the compliant region  110   a  may radially compress facilitating entry into the bore. 
         [0029]      FIG. 4 b    discloses a perspective cross-sectional view of another embodiment of a holder  100   b  comprising a body  101   b  and shank  111   b.  A compliant region  110   b  with a bellows shape may comprise a thin wall  112   b  that may flex when subjected to radial or axial compression or expansion. 
         [0030]      FIG. 5 a    discloses a perspective cross-sectional view of an embodiment of a holder  200   a  and a block  220   a.  The holder  200   a  may comprise a shank  211   a  with a compliant region  210   a  shaped to fit within a bore  221   a  of the block  220   a.  A bellows shape of the compliant region  210   a  may comprise a radius  212   a,  wherein the radius  212   a  may compress when urged into the bore  221   a.  Due to a tapering  222   a  of the bore  221   a,  the radius  212   a  may compress further when the holder  200   a  is urged into the bore  221   a  of the block  220   a,  as shown in  FIG. 5   b.    
         [0031]      FIG. 5 b    discloses a perspective cross-sectional view of an embodiment of a holder  200   b  inserted into a bore  221   b  within a block  220   b.  An internal radius of the bore  221   b  may be narrower than an external radius  212   b  of a compliant region  210   b  of the holder  200   b  when not disposed within the bore  221   b  (as shown in  FIG. 5 a   ). Thus the external radius  212   b  of the compliant region  210   b  may contract when urged into the bore  221   b.  Contraction of the radius  212   b  may cause the holder  200   b  to elongate along a central axis  202   b  thereof, enabling the holder  200   b  to extend farther into the bore  221   b.    
         [0032]      FIGS. 6 a  through 6 d    are perspective cross-sectional views of embodiments of holders comprising compliant regions of various geometries. For example, in the embodiment shown in  FIG. 6 a    a holder  300   a  has a compliant region  310   a  comprising a pleat  313   a  that creates additional surface area allowing for more axial expansion when inserted into a bore (shown in  FIG. 5 ). In  FIG. 6 b   , another embodiment of a compliant region  310   b  comprises a sharp accordion shape  314   b  with three pleats  315   b.  Another embodiment shown in  FIG. 6 c    comprises a compliant region  310   c  comprising a smooth accordion shape  316   c  comprising three pleats  315   c.  In yet another embodiment, shown in  FIG. 6 d   , a compliant region  310   d  comprises a barbed shape  317   d  comprising three pleats  315   d.  Each of these various geometries may contribute to compliance. 
         [0033]      FIG. 7  discloses a perspective cross-sectional view of an embodiment of a holder  400  comprising a shank  401  with a compliant region  410 . The compliant region  410  may comprise a barbed shape  417  with one or more pleats  415 . A distal end  402  of the shank  401  may comprise a threaded portion  403 , wherein threaded components (shown in  FIG. 9 ) for holder installation and removal may be utilized. 
         [0034]      FIG. 8  discloses a perspective cross-sectional view of a holder  500  disposed in a bore  521  within a block  520 . An installation tool  540 , such as a bolt, may be inserted through a hole  504  in a front portion of the holder  500 . The installation tool  540  may pass through a compliant region  510  and apply pressure to a barrier  505  on a distal end of a shank of the holder  500 . The installation tool  540  may be pressed against the barrier  505  by, for example, a hammer (not shown), whereby the holder  500  may elongate axially while the compliant region  510  is compressed radially to facilitate installation. As the installation tool  540  is removed the holder  500  may retract axially while the compliant region  510  expands radially to facilitate retention of the holder  500  within the bore  521 . To remove the holder  500  from the bore  521 , pressure may again be applied to the barrier  505  by the installation tool  540  to radially constrict the compliant region  510  while the holder  500  is withdrawn. 
         [0035]      FIG. 9  discloses a perspective partially cross-sectional view of another embodiment of a holder  600  disposed in a bore  621  within a block  620 . An installation tool  640  with a threaded end  641  may be inserted through a hole  604  and a compliant region  610  of the holder  600  whereby the threaded end  641  may be secured to a threaded portion  603  at a distal end of the holder  600 . In this configuration, the installation tool  640  may apply pressure against the threaded portion  603  which may radially constrict the compliant region  610  to facilitate installation. As the installation tool  640  is removed the compliant region  610  may radially expand to facilitate retention of the holder  600  within the bore  621 . For removal, pressure may again be applied to the threaded portion  603  by the installation tool  640  while the holder  600  is withdrawn. 
         [0036]      FIG. 10  discloses a perspective cross-sectional view of embodiments of a portion of a holder  700  comprising a compliant region juxtaposed with a portion of a holder  750  lacking a compliant region, both disposed in a bore within a block  720 . As can be seen, the holder  700  comprising the compliant region may extend further into the block  720  than the holder  750  without the compliant region. 
         [0037]      FIGS. 11 a  and 11 b    discloses perspective cross-sectional views of embodiments of a compliant region  810   a,    810   b  comprising a sharp accordion shape  814   a,    814   b.  To form an interior of the sharp accordion shape  814   a,    814   b,  a machine tool  850   a,    850   b  may be inserted into an opening  819   a,    819   b  to machine an interior thereof. 
         [0038]      FIGS. 12 a  through 12 c    disclose perspective cross-sectional views of various embodiments of installation tools. For example,  FIG. 12 a    shows a holder  900   a  disposed in a bore within a block  920   a.  The holder  900   a  may comprise a threaded portion  906   a  disposed within the holder  900   a  for receiving a threaded end of an installation tool  940   a.  The installation tool  940   a  may be inserted through a compliant region  910   a  and into the threaded portion  906   a.  In this configuration, the installation tool  940   a  may axially compress the compliant region  910   a  expanding it radially to help retain the holder  900   a  within the block  920   a.    
         [0039]      FIG. 12 b    shows a holder  900   b  disposed in a bore within a block  920   b.  The holder  900   b  may comprise a threaded portion  906   b  disposed within the holder  900   b  mating with a threaded part of an installation tool  940   b.  The installation tool  940   b  may pass through the threaded portion  906   b  and press against a barrier  905   b  on a distal end of the holder  900   b  causing a compliant region  910   b  disposed between the threaded portion  906   b  and barrier  905   b  to expand axially. This axially expansion may radially constrict the compliant region aiding in installation or removal of the holder  900   b.    
         [0040]      FIG. 12 c    shows a holder  900   c  disposed in a bore within a block  920   c.  The holder  900   c  may comprise a hole  904   c  running therethrough to a compliant region  907   c.  An retention tool  940   c  may be disposed in the hole  904   c  and thread into a threaded portion  903   c  disposed at a distal end of the holder  900   c.  By so doing, the retention tool  940   c  may axially compress the compliant region  907   c  causing it to expand radially and aiding in retaining the holder  900   c  within the block  920   c.  In this embodiment, the retention tool  940   c  may remain with the holder  900   c  until removal. 
         [0041]      FIG. 13  discloses a perspective cross-sectional view of a pick  4100  disposed directly in a bore within a block  4120  without the use of a holder. The pick  4100  may comprise a body  4101  attached to a shank  4160 . The shank  4160  comprises a compliant region  4110  wherein axial and radial expansion or contraction may occur. The shank  4160  may further comprise a threaded hole  4106  disposed therein for receiving an installation tool  4140 . The installation tool  4140  may be inserted through the compliant region  4110  and into the threaded hole  4106  and may axially compress the compliant region  4110  causing it to expand radially to aid in retaining the pick  4100 . Alternatively, unthreading the installation tool  4140  may allow the compliant region to axially expand and radially contract allowing for removal of the pick  4100 . 
         [0042]    Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the subject matter of this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. Throughout the text and claims, use of the word “about” reflects the penumbra of variation associated with measurement, significant figures, and interchangeability, all as understood by a person having ordinary skill in the art to which this disclosure pertains. Additionally, throughout this disclosure and the accompanying claims, it is understood that even those ranges that may not use the term “about” to describe the high and low values are also implicitly modified by that term, unless otherwise specified.