Patent Publication Number: US-9850755-B2

Title: Bit configuration for a cutter head

Description:
BACKGROUND 
     The present invention relates to mining machines. Specifically, the present invention relates to a configuration of cutting bit assemblies located on a mining machine. 
     Conventional continuous mining machines include a cutter head including multiple cutting bit assemblies operable to cut into a mining surface. In some embodiments, each cutting bit assembly includes a bit coupled to a holder block, and the holder block is affixed to a rotating drum. In some embodiments, the bit may be received within a sleeve that is in turn secured within the holder block. The cutting bit assemblies are positioned and oriented on the cutter head to increase the performance or efficiency of the continuous mining machine as it cuts material from the mine face. 
     SUMMARY 
     In one aspect, a cutter head for a mining machine includes a drum having a first end and a second end and defining a drum axis extending between the first end and the second end. The drum is rotatable about the drum axis, and a drum plane extends perpendicular to the drum axis. The cutter head includes a plurality of cutting bit assemblies secured to an outer surface of the drum proximate the first end of the drum. Each cutting bit assembly includes a block and a bit. The block has a bore, and the bit is positioned at least partially in the bore of the block and includes a tip configured to engage a mine surface. The bit defines a bit axis, and the bit axis defines a first lean angle relative to the drum plane. The plurality of cutting bit assemblies includes a first series having four first bits. Each of the first bits includes a first tip and defines a first bit axis oriented at a first lean angle relative to the drum plane. The first lean angle is between about 60 degrees and about 75 degrees. 
     In another aspect, a cutter head for a mining machine includes a drum having a first end and a second end and defining a drum axis extending between the first end and the second end. The drum is rotatable about the drum axis with a drum plane extending perpendicular to the drum axis. The cutter head includes a first bit coupled to the drum having a first tip and defining a first bit axis. The first bit axis is oriented at a first lean angle relative to a drum plane. The cutter head includes a second bit coupled to the drum having a second tip and defining a second bit axis. The second bit axis is oriented at a second lean angle relative to the drum plane. The cutter head includes a third bit coupled to the drum having a third tip and defining a third bit axis. The third bit axis is oriented at a third lean angle relative to the drum plane. The cutter head includes a fourth bit coupled to the drum having a fourth tip and defining a fourth bit axis. The fourth bit axis is oriented at a fourth lean angle relative to the drum plane. The cutter head includes a fifth bit coupled to the drum having a fifth tip and defining a fifth bit axis. The fifth bit axis is oriented at the first lean angle relative to the drum plane. The first lean angle is greater than the second lean angle, the second lean angle is greater than the third lean angle, and the third lean angle is greater than the fourth lean angle. As the drum rotates about the drum axis, the bits having a first lean angle engage the mine surface at least twice as frequently as a bit having any of the other lean angles. 
     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 a mining machine including a cutter head. 
         FIG. 2  is a perspective view of a portion of the cutter head of  FIG. 1 . 
         FIG. 3  is a cross sectional view of a portion of the cutter head of  FIG. 2  viewed along section  3 - 3 . 
         FIG. 4  is a rear view of the cutter head of  FIG. 2  including a plurality of cutting bit assemblies. 
         FIG. 5  illustrates a projection of the cutter head of  FIG. 2  illustrating a configuration of the plurality of cutting bit assemblies. 
     
    
    
     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. The use of “including,” “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected” and “coupled” are used broadly and encompass both direct and indirect mounting, connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical or hydraulic connections or couplings, whether direct or indirect. Also, electronic communications and notifications may be performed using any known means including direct connections, wireless connections, etc. 
       FIG. 1  illustrates a mining machine, such as a continuous miner  10 , including a frame  14  that is supported for movement, for example by tracks  18 . The continuous miner  10  further includes a boom  22  and a cutter head  26  supported on the boom  22 . In the illustrated embodiment, the frame  14  also includes a gathering head  30  and a conveyor  34  extending from a first or front end of the frame  14  toward a second or rear end of the frame  14 . After material is cut from a mine face by the cutter head  26 , the material may fall to the mine floor. The gathering head  30  includes a pair of rotating arms  38  that engage the cut material below the cutter head  26  and direct the cut material onto the conveyor  34 . The conveyor  34  transports the cut material along a longitudinal axis (not shown) of the frame  14 , from the gathering head  30  to a second conveyor (not shown) positioned proximate the second or rear end of the frame  14 . 
     The boom  22  includes one end pivotably coupled to the frame  14  and another end supporting the cutter head  26 . The boom  22  is pivotable about a pivot axis  54  that is generally transverse to the longitudinal axis of the frame  14 . The boom  22  is pivoted by a pair of actuators  58  that are coupled between the frame  14  and the boom  22 . In the illustrated embodiment, the actuators  58  are hydraulic jacks or cylinders. 
     The cutter head  26  includes an elongated drum  62  and cutting bit assemblies  66  secured to an outer surface of the drum  62 . In the illustrated embodiment, the drum  62  defines a drum axis  70  that is generally parallel to the pivot axis  54  of the boom  22 , and the drum  62  is rotatable about the drum axis  70 . In one embodiment, the cutter head  26  includes end portions  60  and an intermediate portion  56  positioned between the end portions  60 . A proximal end  61  of the end portions  60  is adjacent the intermediate portion  56 , whereas a distal end  63  of the end portions  60  is located opposite (e.g., axially spaced apart from) the proximal end  61 . In other embodiments, the cutter head  26  may include fewer or more than three portions. 
       FIG. 2  illustrates one of the end portions  60 . In the illustrated embodiment, an outer surface of each end portion  60  is stepped such that the proximal end  61  has a larger diameter than the distal end  63 . Referring now to  FIGS. 2 and 3 , the outer surface of the drum  62  includes pedestals  68 , and each pedestal  68  defines a surface  64 . Each cutting bit assembly  66  includes a pick or bit  74 , a sleeve  78 , and a holder block  82 , and each holder block  82  is affixed to a surface  64  of a corresponding pedestal  68 . The sleeve  78  provides a protective interface between the bit  74  and the holder block  82 . In some embodiments, the cutting bit assembly  66  may not include the sleeve. 
     As shown in  FIG. 3 , in the illustrated embodiment each bit  74  includes a first portion  86  having a tip  88  for engaging a mine face to remove material, and a second portion or shank  90 . The shank  90  of each bit  74  is positioned within a bore of the sleeve  78 , which is in turn positioned in a bore of the holder block  82 . The shank  90  defines a bit axis  92 . In one embodiment, the bit axis  92  passes through the tip  88  and the bit axis  92  may be concentrically aligned with the bores of the sleeve  78  and the holder block  82 . In the illustrated embodiment, the end of the shank  90  is secured relative to the sleeve  78  by a clip, and the bit  74  is selectively removable from the holder block  82  and may be replaced by a new bit  74 . 
     With reference to  FIG. 3 , the tip  88  of the illustrated cutting bit assembly  66  is spaced from the drum axis  70  by a radial distance. A first plane  94  (e.g., tangent plane) is tangent to a cutting trajectory at the tip  88  of the bit  86 . Stated another way, the first plane  94  intersects the tip  88 , and the first plane  94  is perpendicular to a radial line extending from the drum axis  70  to the tip  88 . In the illustrated embodiment, the first plane  94  is parallel to the drum axis  70 . Each cutting bit assembly  66  includes an attack angle θ defined between the bit axis  92  of the bit shank  90  and the first plane  94 . 
     Referring to  FIGS. 2 and 4 , the illustrated cutting bit assemblies  66  located adjacent the distal end  63  of the end portion  60  define an end ring bit assembly  98 . The end ring bit assembly  98  includes bits  74   a ,  74   b ,  74   c ,  74   d  having corresponding tips  88   a ,  88   b ,  88   c ,  88   d  to engage the mine surface axially beyond the distal end  63  (e.g., positioned to the side of the cutter head  26 ). The remaining surface of the end portion  60  includes bits  74   e  including tips  88   e  for engaging the mine surface in front of the cutter head  26 . 
     As shown in  FIG. 4 , a second plane  102  (e.g., drum plane) extends perpendicular to the drum axis  70 . In the illustrated embodiment, a lean angle β extends between the second plane  102  and the bit axis  92  of each cutting bit assembly  66 . For purposes of this description, a positive lean angle is defined as an angle extending outwardly or away from the distal end  63  of the end portion, and away from the second plane  102 . Similarly, a negative lean angle is defined as an angle extending outwardly from the distal end  63  and toward the proximal end  61 . In cases where the bit axis  92  is aligned in the second plane  102  (or a plane parallel to the second plane  102 ), the lean angle is zero degrees. In the illustrated embodiment, some of the cutting bit assemblies  66  include a bit axis  92  oriented at a lean angle of zero degrees. Other cutting bit assemblies include bits  74   a ,  74   b ,  74   c ,  74   d  oriented at various lean angles β. In one embodiment, the surface  64  of a respective pedestal  68  is oriented at a desired lean angle relative to the drum axis  70  such that the cutting bit assembly  66  coupled to the surface  64  has the desired lean angle β. 
     In some embodiments, at least one cutting bit assembly  66  may be supported at a lean angle relative to the second plane  102 . If the lean angle β is non-zero, the bit axis  92  may be projected onto the second plane  102 . An angle between the projected bit axis and the first plane  94  defines an effective attack angle. In one embodiment, the effective attack angle θ is between about 45 degrees and about 55 degrees. In one embodiment, the effective attack angle is 50 degrees. In other embodiments, the effective attack angle may be differently configured dependent upon other parameters (e.g., geometry of the bit, type of material to be cut, depth of cut of the cutter head, etc.). In addition, in some embodiments the effective attack angle for all of the cutting bit assemblies  66  (bits  74   a - 74   e ) is the same. 
     In the illustrated embodiment, the bit  74   a  includes a first lean angle β a  that is defined between the second plane  102  and the bit axis  92   a , the bit  74   b  includes a second lean angle β b  that is defined between the second plane  102  and the bit axis  92   b , the bit  74   c  includes a third lean angle β c  that is defined between the second plane  102  and the bit axis  92   c , and the bit  74   d  includes a fourth lean angle β d  that is defined between the second plane  102  and the bit axis  92   d.    
     In one embodiment, the first lean angle β a  is between about 60 degrees and about 75 degrees. In one embodiment, the second lean angle β b  is between about 30 degrees and about 45 degrees. In one embodiment, the third lean angle β c  is between about 15 degrees and about 25 degrees. In one embodiment, the fourth lean angle β d  is between about 0 degrees and about 10 degrees. In one embodiment, the first lean angle β a  is between about 60 degrees and about 65 degrees. In one embodiment, the second lean angle β b  is between about 30 degrees and about 35 degrees. In one embodiment, the third lean angle β c  is between about 15 degrees and about 20 degrees. In one embodiment, the fourth lean angle β d  is between about 0 degrees and about 5 degrees. In addition, a fifth lean angle β e  of the bits  74   e  (i.e., the lean angle of the bits  74   e  that are not part of the end ring bit assembly  98 ) may be between about 0 degrees and 10 degrees. In one embodiment, the first lean angle β a  is about 60 degrees. In one embodiment, the second lean angle β b  is about 30 degrees. In one embodiment, the third lean angle β c  is about 20 degrees. In one embodiment, the fourth lean angle β d  is about 0 degrees. In one embodiment, and the fifth lean angle β e  is about 0 degrees. 
       FIG. 5  illustrates the tip  88  of the bit  74  for each cutting assembly  66  of the drum end portion  60  projected onto a flat or planar representation. Each tip  88  is represented as a circle. Each vertical line in the projection represents a cutting line aligned with at least one tip  88  and extending circumferentially around the surface of the end portion  60 . Each horizontal line is aligned with at least one tip  88  and extends axially along the end portion  60  (although the circles are shown above the horizontal lines, it is understood that the horizontal lines coincide with the tips  88 ). 
     The end portion  60  includes a main portion positioned adjacent the proximal end  61  and the end ring bit assembly  98  positioned adjacent the distal end  63 . The end ring bit assembly  98  includes four bits  74   a , each of which includes a tip  88   a . The tips  88   a  define a first cutting line  106 . In addition, two bits  74   b  each include tips  88   b  that define a second cutting line  110 . Two bits  74   c  each include tips  88   c  that define a third cutting line  114 , and two bits  74   d  each include tips  88   d  that define a fourth cutting line  118 . In the illustrated embodiment, each of the bits  74   e  in the main portion includes a tip  88   e  defining an individual cutting line; that is, none of the bits  74   e  are aligned along a common cutting line. 
     As the cutter head  26  rotates about the drum axis  70  ( FIG. 2 ), the cutting lines  106 ,  110 ,  114 ,  118  each define an individual cutting plane. In the illustrated embodiment, the first cutting line  106  is axially separated from the second cutting line  110  by a first distance D 1 , the second cutting line  110  is axially separated from the third cutting line  114  by a second distance D 2 , the third cutting line  114  is axially separated from the fourth cutting line  118  by a third distance D 3 , and the fourth cutting line  118  is axially separated from the cutting bit  74   e  that is adjacent the end ring bit assembly  98  by a fourth distance D 4 . In one embodiment, the first distance D 1  is between about 27 millimeters and 47 millimeters, the second distance D 2  is between about 60 millimeters and 80 millimeters, the third distance D 3  is between about 67 millimeters and 87 millimeters, and the fourth distance D 4  is between about 62 millimeters and 82 millimeters. In one embodiment, the first distance D 1  is about 37 millimeters, the second distance D 2  is about 70 millimeters, the third distance D 3  is about 77 millimeters, and the fourth distance D 4  is about 72 millimeters. 
     During a full rotation of the cutter head  26 , the end ring bit assembly  98  engages the mine surface and completes a cutting sequence. In the illustrated embodiment, the cutting sequence includes engaging the mine surface with the tips of the end ring bits in the following order: bit  74   d , bit  74   b , bit  74   a , bit  74   c , bit  74   a , bit  74   d , bit  74   b , bit  74   a , bit  74   c , and bit  74   a . Consequently, the end ring bit assembly  98  includes ten bits  74  that each engages the mine surface. The outermost bits  74   a  engage the mine surface twice as frequently compared to each of the bits  74   b ,  74   c ,  74   d  (four times per rotation compared to two times per rotation) and four times as frequently compared to each bit  74   e  on the main portion (four time per rotation compared to once per rotation for each bit  74   e ). 
     In the illustrated embodiment, the tips  88   a ,  88   b ,  88   c ,  88   d , of the bits  74   a ,  74   b ,  74   c ,  74   d  are angularly spaced apart from each other by a circumferential angle φ 1  about the drum axis  70 . Each tip  88   a ,  88   b ,  88   c ,  88   d  is spaced apart from the nearest adjacent tip by an angle, and the angle is equal for each of the tips  88   a ,  88   b ,  88   c ,  88   d . Stated another way, the tips  88   a ,  88   b ,  88   c ,  88   d  are equally spaced around the drum  62 . In one embodiment, the circumferential angle φ 1  between each tip  88   a ,  88   b ,  88   c ,  88   d  of the end ring bit assembly  98  is about 36 degrees. In one embodiment, the circumferential angle φ 2  between adjacent tips  88   e  of the main portion is about 22.5 degrees. In other embodiments, the circumferential angle between adjacent bits may be more or less, and/or the circumferential angle between the bits may be non-uniform such that the space between some bits is greater than the space between others. 
     The improved configuration of the end ring bit assembly  98  (the combination of cutting bits  74  with the attack angle θ, the lean angles β a -β d , the circumferential angle φ, and/or the axial distances D 1 -D 4 ) causes the reaction forces applied to the bits  74   a ,  74   b ,  74   c ,  74   d  to be more evenly distributed such that the tips  88   a ,  88   b ,  88   c ,  88   d  reducing the risk of premature failure of a bit or a group of bits due to overloading. In addition, the configuration of the end ring bit assembly  98  inhibits direct contact between the mine surface and the elongated drum  62 , the pedestals  68 , the holder blocks  82 , and/or the sleeves  78 , thereby preventing sparks. Furthermore, in some embodiments, all of the bits  74   a - 74   e  on the drum  62  include the same effective attack angle, providing more even distribution of cutting forces over the bits  74   a - 74   e  and providing a rotationally balanced cutter head  26  to reduce cutting vibrations during a mining operation. 
     Although the configuration of the cutting bit assemblies has been described above with respect to an exemplary mining machine (e.g., a continuous mining machine), it is understood that the configuration of cutting bit assemblies could be incorporated onto various types of cutter heads and various types of mining machines. 
     Thus, the invention provides, among other things, a bit configuration for a cutter head. Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.