Patent Publication Number: US-7722127-B2

Title: Pick shank in axial tension

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/773,271 which was filed on Jul. 3, 2007. U.S. patent application Ser. No. 11/773,271 is a continuation-in-part of U.S. patent application Ser. No. 11/766,903 filed on Jun. 22, 2007. U.S. patent application Ser. No. 11/766,903 is a continuation of U.S. patent application Ser. No. 11/766,865 filed on Jun. 22, 2007. U.S. patent application Ser. No. 11/766,865 is a continuation-in-part of U.S. patent application Ser. No. 11/742,304 which was filed on Apr. 30, 2007 now U.S. Pat. No. 7,475,948. U.S. patent application Ser. No. 11/742,304 is a continuation of U.S. patent application Ser. No. 11/742,261 which was filed on Apr. 30, 2007 now U.S. Pat. No. 7,469,971. U.S. patent application Ser. No. 11/742,261 is a continuation-in-part of U.S. patent application Ser. No. 11/464,008 which was filed on Aug. 11, 2006 now U.S. Pat. No. 7,338,135. U.S. patent application Ser. No. 11/464,008 is a continuation-in-part of U.S. patent application Ser. No. 11/463,998 which was filed on Aug. 11, 2006 now U.S. Pat. No. 7,384,105. U.S. patent application Ser. No. 11/463,998 is a continuation-in-part of U.S. patent application Ser. No. 11/463,990 which was filed on Aug. 11, 2006 now U.S. Pat. No. 7,320,505. U.S. patent application Ser. No. 11/463,990 is a continuation-in-part of U.S. patent application Ser. No. 11/463,975 which was filed on Aug. 11, 2006 now U.S. Pat. No. 7,445,294. U.S. patent application Ser. No. 11/463,975 is a continuation-in-part of U.S. patent application Ser. No. 11/463,962 which was filed on Aug. 11, 2006 now U.S. Pat. No. 7,413,256. U.S. patent application Ser. No. 11/463,962 is a continuation-in-part of U.S. patent application Ser. No. 11/463,953, which was also filed on Aug. 11, 2006 now U.S. Pat. No. 7,464,993. The present application is also a continuation-in-part of U.S. patent application Ser. No. 11/695,672 which was filed on Apr. 3, 2007 now U.S. Pat. No. 7,396,086. U.S. patent application Ser. No. 11/695,672 is a continuation-in-part of U.S. patent application Ser. No. 11/686,831 filed on Mar. 15, 2007 now U.S. Pat. No. 7,464,993. All of these applications are herein incorporated by reference for all that they contain. 
    
    
     BACKGROUND OF THE INVENTION 
     In the asphalt industry, pavement may be degraded using attack picks, and in the mining industry, attack picks may be used to break minerals and rocks. Attack picks may also be used when excavating large amounts of hard materials. In asphalt recycling, often, a drum supporting an array of attack picks disposed within holders attached, together making up a degradation assembly, may be rotated and moved so that the attack picks engage a paved surface causing the picks and/or holders to wear. 
     U.S. Pat. No. 4,274,678 to Herridge, which is herein incorporated by reference for all that it contains, discloses a mineral mining pick boss having a socket therein for the reception of a shank of a mineral mining pick and a locking arrangement for retaining the shank, the locking arrangement comprising a plug received in a bore extending through the boss transversely of the socket the arrangement being such that the bore intersects the socket, the plug comprising a body of a resilient material (e.g. neoprene) having bonded into the periphery thereof at spaced locations a plurality of metallic members one of which protrudes from the bore into the socket for frictional engagement with the shank of the tool so as to retain the tool in position, the other(s) of the metallic members being disposed within the bore, and the arrangement of the metallic members being such that the plug may be removed from the bore, rotated and re-inserted to change the metallic member which protrudes into the socket. 
     U.S. Pat. No. 4,484,783 to Emmerich, which is herein incorporated by reference for all that it contains, discloses a mining bit to be mounted for rotation in a bore of a support block or on a drill steel having a retention configuration opposite the working end. A bit shank is formed opposite the working end. A bit shank is formed with an abutment flange at the insertion end and a recess adjacent said flange to receive flexed resilient fingers of a resilient retention ring during insertion of said ring in said bore. A fulcrum land supports an un-split end of said ring. The resilient fingers carry an annular bulge projection which engages an annular recess in a support bore. The ring can extend the length of the retention shank to serve as a wear sleeve. With a drill steel, the retention ring is mounted on an extending insert to cooperate with a female recess in a hollow bit. 
     U.S. Pat. No. 6,382,733 B1 to Parrott, which is herein incorporated by reference for all that it contains, discloses a mounting member, for a mining cutting apparatus, which has an enlarged head incorporating an annular seating shoulder, whilst a circular section pin extends integrally from the head and is adapted to be received in a circular section socket of a pick box and to be retained therein, a circular groove being provided intermediate the ends of the pins to receive a fluid sealing member, with a first portion of the pin being of such diameter that, in use, it is an interference fit within a pick box socket. The invention also includes a pick box; a mounting member and a pick box combination; a drum for a mineral cutting apparatus; mineral cutting apparatus; a road planning machine; a mining machine, and a tunneling machine. 
     Examples of degradation assemblies from the prior art are disclosed in U.S. Pat. No. 6,863,352 B2 to Sollami, U.S. Pat. No. 5,392,870 to Clapham et al., U.S. Pat. No. 4,537,448 to Ketterer, U.S. Pat. No. 3,397,013 to Krekeler, U.S. Pat. No. 4,575,156 to Hunter et al., U.S. Pat. No. 3,796,464 to Hansen et al., U.S. Pat. No. 4,678,238 to Emmerich, which are all herein incorporated by reference for all they contain. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a degradation assembly comprises a holder attached to a driving mechanism and comprises a longitudinal central bore. The bore comprises an opening at a distal end from the driving mechanism. A pick comprising a body intermediate a shank and an impact tip is connected to the holder, the shank being disposed in the central bore of the holder and the body extending from the opening of the bore. A tensioning mechanism is disposed within the bore and is adapted to put the shank in axial tension. 
     In some embodiments, a portion of the central bore may have an expanded diameter. A tapered portion of the central bore may be formed intermediate the opening and the expanded diameter portion and may taper out from a center axis of the bore towards the expanded diameter portion. A reduced diameter portion of the shank may be disposed intermediate the pick body and a bottom end of the shank. A spring may be disposed around the reduced diameter portion of the shank and once the shank with the spring is disposed in the bore the spring may engage the tapered portion inducing axial tension in the shank. 
     A washer may be disposed intermediate the body and the holder. The holder may have a knurled interface that engages the washer preventing the washer from rotating about the center axis. The pick may be adapted to rotate about its central axis. 
     The body may comprise a conical carbide bolster with a tapered recess. The shank may have a tapered end opposing the bottom end adapted to fit in the tapered recess. 
     The holder may comprise a lubricant reservoir adapted to apply a lubricant to the shank. The lubricant reservoir may be pressurized and the lubricant reservoir may comprise a filling port. The lubricant reservoir may be adapted to hydraulically disassemble the degradation assembly. The lubricant reservoir may be disposed within the driving mechanism. 
     A seal assembly may be proximate the opening and disposed intermediate the pick and the holder. The seal assembly may comprise an o-ring partially disposed in a reentrant proximate a junction of the shank and the body. The seal assembly may also comprise an o-ring disposed at the distal end of the holder and which may control the movement of a lubricant. 
     The holder may comprise a block and/or extension element. The degradation assembly may be part of an asphalt milling machine, a trenching machine, a coal mining machine, or combinations thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional diagram of an embodiment of a plurality of degradation assemblies on a rotating drum attached to a motor vehicle. 
         FIG. 2  is a cross-sectional diagram of an embodiment of a degradation assembly. 
         FIG. 3  is a cross-sectional diagram of another embodiment of a degradation assembly. 
         FIG. 4  is a cross-sectional diagram of another embodiment of a degradation assembly. 
         FIG. 5  is a cross-sectional diagram of another embodiment of a degradation assembly. 
         FIG. 5   a  is a cross-sectional diagram of another embodiment of a degradation assembly. 
         FIG. 6  is an orthogonal diagram of an embodiment of a drill bit. 
         FIG. 7  is an orthogonal diagram of another embodiment of a drill bit. 
         FIG. 8  is a perspective diagram of an embodiment of a trencher. 
         FIG. 9  is an orthogonal diagram of another embodiment of a trencher. 
         FIG. 10  is an orthogonal diagram of an embodiment of a coal trencher. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT 
       FIG. 1  is a cross-sectional diagram of an embodiment of at least one pick  101  attached to a rotating drum  103  connected to the underside of a pavement recycling machine  100 . The recycling machine  100  may be a cold planer used to degrade man-made formations such as pavement  104  prior to the placement of a new layer of pavement. Picks  101  may be attached to the drum  103  bringing the picks  101  into engagement with the formation. A holder  102  is attached to the rotating drum  103 , and the pick  101  is inserted into the holder  102 . The holder  102  may hold the pick  101  at an angle offset from the direction of rotation, such that the pick  101  engages the pavement at a preferential angle. Collectively, the pick  101 , the holder  102 , and the drum  103  may comprise a degradation assembly. 
     Referring to  FIG. 2 , an embodiment of the degradation assembly  105  may comprise a holder  102 , a drum  103 , and a pick  101 ; the holder  102  comprises a block  201  and an extension  202 . The block  201  is attached directly to the drum  103  by bolts  220 . In some embodiments, the block is secured to the drum by a weld. A recess is formed in the block  201  adapted to receive and retain the extension  202 . A hydraulic reservoir  218  containing a fluid is disposed intermediate the block  201  and the extension  202 . A filling port  217  adjacent to the hydraulic reservoir  218  enables outside access to the hydraulic reservoir  218 . 
     The extension  202  comprises a central bore  210 ; the central bore  210  comprising an opening at a distal end of the extension  202 , and a closed end opposing the opening of the bore  210 . A portion  211  of the bore tapers out and away from the central axis. The tapered portion  211  of the bore may taper into an expanded diameter portion  212  of the central bore  210 . The expanded diameter  212  portion is located proximate the closed end of the bore  210 . 
     The pick  101  may have a tip  204  comprising a diamond tip bonded to a cemented metal carbide substrate at a non-planar interface. The tip  204  may be bonded to a pick body comprising a cemented metal carbide bolster  203 . A tapered recess is formed in the end of the carbide bolster  203  opposing the tip  204 . A steel shank  221  has a tapered interface  205  adapted to fit in the tapered recess connecting the carbide body  203  and the steel shank  221 . 
     The steel shank  221  may have a reduced diameter portion  208  disposed intermediate the carbide body  203  and the opposing end of the shank  221 . A tensioning mechanism  250  comprising a radially expandable spring  209  is disposed around the reduced diameter portion  208  such that it may not slideably move along the length of the shank  221  beyond the reduced diameter portion  208 . The outermost diameter of the spring  209  is larger than the diameter of the shank  221 . Compressed, the spring  209  may have a diameter less than or equal to the diameter of the shank  221 . 
     The pick  101  is connected to the extension  202  by placing the shank  221  into the central bore  210 ; the spring  209  is compressed as it passes the opening of the bore  210 . As the shank  221  reaches the tapered portion  211  of the bore  210  the spring  209  expands in diameter and pulls the pick  101  downward against the extension  202 . The reduced diameter portion  208  of the shank  221  and the spring  209  never reach the expanded diameter portion  212  of the bore  210  yet remain in the tapered portion  211  of the bore  210 . Because the spring  209  is adapted to expand in diameter as the bore  210  diameter increase, the spring  209  will continue to induce an axial tensional force in the shank  221  so long as the spring  209  remains in the tapered portion  211  of the bore  210 . The axial tensional force in the shank  221  maintains the connection of the pick  101  to the extension  202 . The pick  101  may be rotatable while connected to the extension  202 . 
     A washer  206  may be disposed intermediate the pick body  203  and the extension  202 . The extension  202  may have a knurled interface  219  that engages the washer  206  preventing the washer  206  to rotate about the center axis without inhibiting the rotatability of the pick  101 . In some embodiments, the tension exerted on the pick is sufficient enough to substantially rotationally fix the washer against the holder, even without knurling, while still allowing the pick to rotate. 
     The bore may also contain a lubricant reservoir  213  that may supply lubricant to the shank  221  assisting the rotatability of the pick  101  by reducing friction. A seal assembly proximate the opening of the bore  210  and disposed intermediate the pick  101  and the extension  202  may comprise one o-ring  207  partially disposed in a reentrant proximate a junction of the shank  221  and the body  203 . The seal assembly may also comprise another o-ring  207  disposed at the distal end of the extension  202  and control the movement of the lubricant as it lubricates the shank  221  and pick  101 . A filling port  217  adjacent to the lubricant reservoir  213  enables outside access to the lubricant reservoir  213 . The filling port  217  may comprise a bore  216  adapted to protect the filling port  217  while the degradation assembly  105  is in use. The lubricant reservoir  213  may also comprise a plunger  214  and a spring  215  to apply continual pressure on the lubricant. 
     Referring now to  FIG. 3  additional lubricant  301  may be introduced to the lubricant reservoir  213  through the filling port  217  when the lubricant reservoir  213  runs out of lubricant. Additional lubricant  301  may also be added to the lubricant supply of the lubricant reservoir  213  through the filling port  217  to completely remove the shank  221  hydraulically from the bore  210 . Additional lubricant  301  may also be added to the lubricant supply of the lubricant reservoir  213  through the filling port  217  to partially remove the shank  221  hydraulically from the bore  210  creating a gap  302  intermediate the pick  101  and extension  202 . A tool may then be inserted into the gap  302  to remove the shank  221  from the bore  210  by prying or pulling. 
     Additional fluid  301  may be added to the fluid supply of the hydraulic reservoir  218  through the filling port  217  to completely remove the extension  202  hydraulically from the block  201 . Additional fluid  301  may be added to the fluid supply of the hydraulic reservoir  218  through the filling port  217  to partially remove the extension  202  hydraulically from the block  201  creating a gap  303 . A tool may then be inserted into the gap  303  to remove the extension  202  from the block  201  by prying or pulling. 
       FIG. 4  discloses another embodiment of the present invention wherein the degradation assembly  105  may not comprise the hydraulic reservoir  218 . The pick  101  may have a tip  204  comprising a diamond tip bonded to a cemented metal carbide substrate at a non-planar interface, a body  400  comprising a cemented metal carbide portion  401  and a steel portion  402 , and a shank  221 . 
     Referring to  FIG. 5 , the holder  102  may comprise a block  201 . A lubricant reservoir  213  is disposed with in the block  201  and provides lubricant to the shank  221 . The lubricant reservoir  213  may be connected to a fluid reservoir  501  disposed in the drum  103  by a channel  507 . The fluid reservoir  501  may supply the lubricant reservoir  213  with additional lubricant. Additional lubricant may be added to the fluid reservoir  501  through a filling port  217 . The shank  221  may be removed partially or completely from the bore  210  hydraulically by adding additional lubricant to the fluid reservoir  501  and lubricant reservoir  213  till the inside pressure compresses the spring  209  and forces the shank  221  outward. 
       FIG. 5   a  discloses a steel shank  221  fit into a pocket  550  formed in the bottom side  551  of a carbide bolster  203 . The shank  221  in the pocket  550  comprises at least one compliancy groove  552 . The carbide bolster  203  contacts the holder  102  directly. 
     Degradation assemblies  105  may be used in various applications.  FIGS. 6 through 7  disclose various wear applications that may be incorporated with the present invention.  FIG. 6  discloses a drill bit  600  typically used in water well drilling.  FIG. 7  discloses a drill bit  700  typically used in subterranean, horizontal drilling. These bits  600 ,  700 , and other bits, may be consistent with the present invention. 
     The degradation assembly  105  may be used in a trenching machine, as disclosed in  FIGS. 8 through 9 . Degradation assemblies  105  may be disposed on a rock wheel trenching machine  800  as disclosed in  FIG. 8 . Referring to  FIG. 9 , the degradation assembly may be placed on a chain that rotates around an arm  902  of a chain trenching machine  901 . 
       FIG. 10  is an orthogonal diagram of an embodiment of a coal trencher  1000 . At least one degradation assembly  105  is connected to a rotating drum  1001  that is degrading coal  1002 . The rotating drum is connected to an arm  1003  that moves the drum vertically in order to engage the coal  1002 . The arm  1003  may move by that of a hydraulic arm  1004 , it may also pivot about an axis or a combination thereof. The coal trencher  1000  may move about by tracks, wheels, or a combination thereof. The coal trencher  1000  may also move about in a subterranean formation. The coal trencher  1000  may be in a rectangular shape providing for easy mobility about the formation. 
     Other applications that involve intense wear of machinery may also be benefited by incorporation of the present invention. Milling machines, for example, may experience wear as they are used to reduce the size of material such as rocks, grain, trash, natural resources, chalk, wood, tires, metal, cars, tables, couches, coal, minerals, chemicals, or other natural resources. 
     Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.