Patent Publication Number: US-8967507-B2

Title: Moveable shaft assembly

Description:
BACKGROUND 
     The present invention relates to the field of mining machines, and particularly to a roll sizer for breaking apart and crushing mined material. 
     Conventional mining roll sizers include a pair of parallel counter-rotating roll assemblies positioned within a crushing chamber. The shafts include a series of picks arranged along the surface. As the roll assemblies rotate, the picks engage material that is fed into the crushing chamber, breaking the material apart until it is small enough to pass around the rolls. During normal operation, it is possible for the chamber to receive a tramp material, which is a very hard, dense material. The picks are unable to break apart the tramp material and pass it through the crushing chamber, causing the rolls to bind and one or more picks to break. This requires the roll sizer to be shut down so that the tramp can be removed and any necessary repairs be made to the roll assemblies. 
     SUMMARY 
     In one embodiment, the invention provides a moveable shaft assembly includes a frame, a first shaft, and a first drive assembly. The frame includes a first support wall and a second support wall opposite the first support wall. The first shaft includes a drive end and a support end and defines a first axis therebetween. The first shaft extends between the first support wall and the second support wall. The first drive assembly rotates the first shaft about the first axis, and the first drive assembly is coupled to the drive end of the first shaft. The first shaft and first drive assembly are moveable relative to the frame in response to a reaction force acting on the first shaft in a direction oblique or transverse to the first axis. 
     In another embodiment, the invention provides a roll sizer for a mining crusher, the roll sizer including a frame, a first mobile shaft support, a second mobile shaft support, a first shaft, and at least one actuator. The frame includes a first support wall and a second support wall. The first support wall includes a first shaft track, and the second support wall includes a second shaft track parallel to the first shaft track. The first mobile shaft support moveably engages the first shaft track. The second mobile shaft support moveably engages the second shaft track. The first shaft includes a drive end and a support end and defines a first axis therebetween. The drive end is coupled to a first gear drive for rotating the first shaft about the first axis. The first shaft extends from the first support wall to the second support wall, and is rotatably supported by the first mobile shaft support and the second mobile shaft support. The at least one actuator applies a force to move the first and second mobile shaft supports along the first and second shaft support tracks, respectively. The first drive assembly moves in a direction parallel to the mobile shaft supports while coupled to the first shaft. 
     In yet another embodiment, the invention provides a method for adjusting a shaft spacing in a roll sizer. The method includes: providing a first shaft defining a first axis and a second shaft defining a second axis parallel to the first axis, the first shaft being rotatable about the first axis; providing a drive assembly coupled to the first shaft for rotating the first shaft; sensing the forces acting on the first shaft; and operating an actuator to provide a force to move the first shaft from a position that is a first distance from the second shaft to a position that is a second distance from the second shaft, the second distance being greater than the first distance, wherein the drive assembly moves with the first shaft. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the roll sizer according to one embodiment of the invention. 
         FIG. 2  is a top view of the roll sizer of  FIG. 1  wherein a first roll assembly is positioned proximate a second roll assembly. 
         FIG. 3  is a top view of the roll sizer of  FIG. 1  wherein the first roll assembly is positioned away from the second roll assembly. 
         FIG. 4  is an enlarged perspective view of the roll sizer of  FIG. 1  with the first drive assembly removed. 
         FIG. 5  is a section view of a portion of the roll sizer of  FIG. 1  taken along line  5 - 5 . 
         FIG. 6  is a side view of a first carriage, a first drive assembly, and a torque arm. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. 
     Although the invention is described below as it relates to a roll sizer, it is important to note that the invention is also applicable to conveyors having a moveable shaft or other devices having a drive shaft that is moveable in response to a force. 
       FIG. 1  illustrates a mining roll sizer  10 . The roll sizer  10  includes a frame  14 , a first roll assembly  22 , a second roll assembly  26 , a first carriage  30 , a second carriage  34 , a first drive assembly  38  supported by the first carriage  30 , a second drive assembly  42  supported in the second carriage  34 , and an actuator  50 . The frame  14  defines an interior chamber  54 . In one embodiment the interior chamber  54  has a rectangular shape. The frame  14  includes a first support wall  62 , a second support wall  66  mounted opposite the first support wall  62 , a pair of mobile shaft supports  74   a ,  74   b  for rotatably supporting the first roll assembly  22 , a pair of stationary shaft supports  78   a ,  78   b  for rotatably supporting the second roll assembly  26 , and a torque arm  80  ( FIG. 5 ). The first support wall  62  and the second support wall  66  each include an elongated slot  82  ( FIG. 4 ) extending through each respective support wall  62  and  66 . The first support wall  62  and the second support wall  66  each include a track  86  ( FIG. 4 ) positioned adjacent the slot  82 . Each of the mobile shaft supports  74   a ,  74   b  moveably engages one of the tracks  86 . In the illustrated embodiment, the mobile shaft supports  74   a ,  74   b  slidably engage the tracks  86 . In other embodiments, the mobile shaft supports  74   a ,  74   b  may move in another manner, such as rolling with respect to the tracks  86 . The torque arm  80  is discussed in further detail below. 
     As shown in  FIGS. 2 and 3 , the first roll assembly  22  is positioned substantially within the interior chamber  54  and includes a first shaft  88  having a drive end  90  and a support end  94  opposite the drive end  90 . The first roll assembly  22  also includes a crushing portion  98  coupled to the first shaft  88 . The first shaft  88  defines a first axis  102  between the drive end  90  and the support end  94 . The drive end  90  extends through the slot  82  in the first support wall  62  and is coupled to the first drive assembly  38  for rotating the first roll assembly  22 . The drive end  90  is rotatably supported by a first mobile shaft support  74   a . The support end  94  extends through the slot  82  of the second support wall  66  and is rotatably supported by a second mobile shaft support  74   b . In one embodiment, the mobile shaft supports  74   a ,  74   b  include a tapered roller bearing for rotatably supporting the first shaft  88 . In other embodiments, another type of bearing may be used. The crushing portion  98  is located within the interior chamber  54  and includes multiple picks  106  that are oriented to point in the direction of rotation of the first shaft  22 . 
     The second roll assembly  26  is positioned substantially within the interior chamber  54  and parallel to the first shaft  88 . The second roll assembly  26  includes a second shaft  108  having a drive end  110  and a support end  114  opposite the drive end  110 . The second roll assembly  26  also includes a crushing portion  118  coupled to the second shaft  108 . The second shaft  108  defines a second axis  122  between the drive end  110  and the support end  114 . The drive end  110  extends through the second support wall  66  and is coupled to the second drive assembly  42  for rotating the second roll assembly  26 . The drive end  110  is rotatably supported by a second stationary shaft support  78   b . The support end  114  extends through the first support wall  66  and is rotatably supported by a first stationary shaft support  78   a . In one embodiment, the stationary shaft supports  78   a ,  78   b  include a tapered roller bearing for rotatably supporting the second shaft  108 . In other embodiments, another type of bearing may be used. The crushing portion  118  is located within the interior chamber  54  and includes multiple picks  126  that are oriented to point in the direction of rotation of the second shaft  26 . 
     The first roll assembly  22  and the second roll assembly  26  are counter-rotating, such that the first roll assembly  22  and the second roll assembly  26  rotate in opposite directions when viewed from a common side. Stated differently, the roll assemblies  22 ,  26  rotate in opposite directions so that the picks  126  rotate over the top of each roll assembly  22 ,  26 . In the embodiment illustrated in  FIG. 3 , as viewed along each axis  102 ,  122  from the first support wall  62 , the first roll assembly  22  rotates in a counter-clockwise direction and the second roll assembly  26  rotates in a clockwise direction. As the first roll assembly  22  and the second roll assembly  26  rotate, the picks  106  of the first roll assembly  22  pass between the picks  126  of the second roll assembly  26  without contacting one another. In other embodiments, the roll assemblies  22 ,  26  may be configured to rotate in another manner. 
     As shown in  FIGS. 2 and 5 , the first carriage  30  is positioned proximate the first support wall  62  and supports the first drive assembly  38 . The first carriage  30  includes a torque arm track  134  ( FIG. 5 ). The first drive assembly  38  includes a first motor  138 , a first gear drive  140 , and a first torque limiter  142 . The first gear drive  140  receives the drive end  90  of the first shaft  88 . The first torque limiter  142  ( FIG. 2 ) removably couples the first motor  138  to the first gear drive  140 , maintaining a mechanical connection to transmit power from the first motor  138  to the first shaft  88 . If a maximum allowable torque is reached, the torque limiter  142  uncouples the first motor  138  and the first gear drive  130  and permits the first motor  138  to rotate freely. As used herein with respect to a torque limiter, the term “uncouple” and variants thereof generally refer to disconnecting a motor and a gear drive to interrupt the transmission of power from the motor to the gear drive. This includes the slipping of friction discs in a torque limiter. 
     As illustrated in  FIGS. 5 and 6 , the torque arm  80  includes a first end  144  coupled to the frame  14  and a second end  146  that moveably engages the torque arm track  134 . The torque arm  80  supports the first carriage  30  for movement with respect to the support wall  66  and secures the first carriage  30  against rotation about the first shaft  88 . In the illustrated embodiment, the second end  146  rolls with respect to the torque arm track  134 . In other embodiments, the second end  146  may move in another manner, such as sliding with respect to the torque arm track  134 . In other embodiments, the torque arm track  134  may be coupled to the frame  14  and the torque arm  80  may be coupled to the first carriage  30 . 
     Referring to  FIG. 2 , the second carriage  34  is positioned proximate the second support wall  66  and supports the second drive assembly  42 . In the illustrated embodiment, the second carriage  34  is coupled to the frame  14 . The second drive assembly  42  includes a second motor  150 , a second gear drive  152 , and a second torque limiter  154 . The second gear drive  152  receives the drive end  110  of the second shaft  108 . The second torque limiter  154  removably couples the second motor  150  to the second gear drive  152 , maintaining a mechanical coupling to transmit power from the second motor  150  to the second shaft  108 . If a maximum allowable torque is reached, the torque limiter  154  uncouples the second motor  150  and the second gear drive  152  and permits the second motor  150  to rotate freely. 
     As shown in  FIGS. 1 and 4 , the actuator  50  includes a pair of extendible hydraulic rams  162  positioned adjacent the mobile shaft supports  74   a ,  74   b  in a direction parallel to the track  86  (only the ram  162  adjacent the first mobile shaft support  74   a  is shown in  FIGS. 1 and 4 ; a similar ram is positioned adjacent the second mobile shaft support  74   b ). Pressure in the ram  162  is maintained by a valve (not shown) and is monitored with a pressure sensor (not shown). When the pressure applied on the ram  162  from the contact with the mobile shaft support  74   a  exceeds a given value, the valve is opened and hydraulic fluid is forced out of the ram  162 , causing the ram  162  to retract. The rams  162  are coupled to the mobile shaft supports  74   a  such that operation of the rams  162  applies a force to the mobile shaft support  74   a  and moves the mobile shaft support  74   a  along the track  86 . The actuator  50  may be configured to either push or pull the shaft support  74   a.    
     In other embodiments, when the rams  162  are extended, the rams  162  contact the mobile shaft supports  74   a ,  74   b  to prevent the mobile shaft supports  74   a ,  74   b  from moving along the track  86 . When the pressure applied on each ram  162  from the contact with the mobile shaft supports  74   a ,  74   b  exceeds a given value, the valve is opened and the pressure on the ram  162  is decreased, causing the ram  162  to retract and allowing the mobile shaft supports  74   a ,  74   b  to move along the track  86 . 
     During operation of the roll sizer  10 , the interior chamber  54  receives material from, for example, a conveyor (not shown). Pieces of the material are urged toward a position between the rotating roll assemblies  22  and  26  where the force of the picks  106 ,  126  converge, breaking apart the pieces to a desirable size. When a hard material, or tramp, is introduced into the interior chamber  54 , the tramp material resists the breaking force of the picks  106 ,  124 . This creates reaction forces on each roll assembly  22 ,  26 , acting in a direction that is either oblique or transverse to each axis  102 ,  122 . As used herein, the term “oblique” refers to a direction that is neither parallel nor perpendicular to either axis  102 ,  122 . As used herein, the term “transverse” refers to a direction that is perpendicular to either axis  102 ,  122 . The reaction forces press the mobile shaft supports  74   a ,  74   b  against the hydraulic rams  162 , increasing the hydraulic pressure acting against the ram  162 . The pressure sensor detects the pressure increase, and sends an electrical signal to a controller to open the valve and reduce pressure on the ram  162 . This allows the rams  162  to retract, allowing the tramp material to pass through the roll assemblies  22 ,  26 . In an alternative embodiment (not shown), the valve may open only by influence of the hydraulic pressure, without the use of an electric sensor. 
     As shown in  FIG. 4 , the retraction of the rams  162  permits the mobile shaft supports  74   a ,  74   b  (and therefore the first roll assembly  22 ) to move along the track  86  in a direction perpendicular to the first axis  102 . The first roll assembly  22  moves from a position spaced apart from the second roll assembly  26  by a first distance  170  ( FIG. 2 ) to a position that is spaced apart from the second roll assembly  26  by a second distance  174  that is greater than the first distance  170 . The first shaft  88  moves within the slot  82  ( FIG. 3 ) in the first support wall  62 , causing the first carriage  30  to move with respect to the frame  14  in a direction parallel to the track  86 . The first carriage  30  is supported throughout this motion by the second end  146  of the torque arm  80  ( FIGS. 5 and 6 ), which moves along the torque arm track  134  ( FIGS. 5 and 6 ). 
     In this manner, the first roll assembly  22  moves away from the second roll assembly  26  in a direction parallel to the track  86 , increasing the space between the first roll assembly  22  and the second roll assembly  26 . This allows the tramp material to pass through the interior chamber  54  without damaging the roll assemblies  22 ,  26 . In one embodiment, the first shaft  88  travels in a first direction parallel to the track  86  through a distance of approximately 12 inches, and travels in a second direction opposite the first direction through a distance of approximately 4 inches. In one embodiment, the first distance  170  is approximately 62 inches, with alternative shaft supports that allow the operator to configure the first distance  170  to be approximately 64 inches, 66 inches, or 68 inches. 
     Thus, the invention provides, among other things, a moveable shaft assembly for a roll sizer. Various features and advantages of the invention are set forth in the following claims.