Patent Publication Number: US-6910651-B2

Title: Material crusher

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority to prior filed U.S. Provisional Application Ser. No. 60/329,192 filed by Applicant herein on Oct. 11, 2001 and titled “Material Crusher.” 

   FIELD OF THE INVENTION 
   The present invention relates to devices and methods for crushing materials such as rocks. 
   BACKGROUND OF THE INVENTION 
   It has been known to crush materials such as rock to produce, for example, gravel, sand, chips or to crush sea shells or other material which may be reduced to finer aggregate. Manufactured sand, that is sand produced by crushing as opposed to naturally occurring sand, is often specified to be used in manufacturing cement for road construction or the like since, unlike natural sand which has been weathered and the facets worn, manufactured sand has sharp facets which provide for binding in the cement product. Hence, manufacturing sand from crushing rock is an important industry to supply sand and, for that matter, manufactured aggregate for cement. 
   In addition to manufacturing sand, rocks are crushed to produce gravel and rock chips for use in aggregate and cement and, for example, decorative rock gravel. In the manufacture of gravel it is important to produce a consistent and predictable crushed product such that there is a minimum of non-conforming product, e.g., sand where chips are being manufactured, which must be screened. It would be advantageous to be able to substantially select the product to be produced (whether it be sand, aggregate or chips) and crush the rocks such that a substantial portion of the crushed material falls in the range of the desired product and that a minimum of the product is lost to nonconforming output. 
   It has also been known to crush frangible materials such as sea shells and the like. 
   One approach to rock crushing is as shown in Pamplin, U.S. Pat. No. 4,257,564 which has a rotating, planar and circular crushing jaw which operates with a conical jaw. The jaws are spaced to define an annular discharge opening. The conical crushing jaw is defined, in annular fashion, about an axially disposed feed tube which supports the rotating components associated with the conical jaw. Rock is fed axially down the axial tube and the jaws rotated which feeds the rock, through centrifugal force, between the jaws where they are crushed. The lower jaw is round and flat and coacts with the conical upper jaw to define a circular nip for crushing of rock. A drawback to this type of rock crusher is that upper jaw is conical which provides an irregular, non-planar crushing face and which, it turn, increases manufacture and replacement costs of the wear surfaces. The bottom jaw is flat and as a result does not cooperate to urge rock to the nip instead relying completely upon centrifugal force. There is no technique to positively feed and direct rock between the jaws. 
   In my prior patent, U.S. Pat. No. 6,170,771 issued Jan. 9, 2001 (the disclosure of which is hereby incorporated by reference), I described a new rock crusher having a polygonal crushing surface. It has been found that the polygonal crushing surface enhanced the crushing ability of the crusher. 
   It has been found that with material crushers of the type described above, product may tend to back-up into the crushing chamber. Product may choke at the the nip of the crusher preventing crushed material from being ejected from the crusher and decreasing throughput. Expanding the nip, while ejecting more product, also results in larger sized aggregate being ejected, which may not be desired. 
   It has further been found that, during crushing, wear patterns can develop on the crushing surfaces leading to premature failure or requiring premature replacement of crushing surface elements. 
   There is, therefore, a need for a material crusher which overcomes the problems of prior rock crushers by, among other features and advantages, configured wear and crushing surfaces for one of the top or bottom crushing rotors which is adapted to reduce and more evenly distribute wear, which provides for less expensive construction and replacement of wear surfaces and which provides a construction to reduce choking and provide for increased ejection of crushed product. 
   SUMMARY OF THE INVENTION 
   Toward this end, a device for crushing material is set forth which includes a housing with a feed port to receive the material to be crushed and a discharge opening for discharging the crushed product. A first rotor is disposed in the housing and has a first axis. The first rotor defines a first crushing surface. A second rotor is disposed in the housing and has a second axis. The second rotor includes a cavity to pass material and a face defining a second crushing surface adapted to be spaced from the first crushing surface and to define to define proximate the perimeter thereof a nip. Opposite the second crushing surface, the second rotor has a cover with at least one feed opening to admit material into the cavity. Means are provided for rotating the first and second rotors about their respective axises to centrifugally direct material between the nip for crushing thereof, and for discharging the crushed material discharged from the housing. 
   To increase throughput and enhance crushing, the one or both of the rotors at the nip includes channels sized for passing crushed material from the nip area of the rotors. For example, the grooves may be formed through the second crushing surface to eject crushed material in addition to material being ejected from the nip. 
   To further increase throughput and reduce wear, the first crushing surface, second crushing surface, or both the first and second crushing surfaces may include projections and ridges to agitate and distribute wear. Still further, channels in the first crushing surface, second crushing surface, or both crushing surfaces may be angled relative to the radius of the respective rotors to provide for ejection of material when the respective rotor is rotated in a clockwise or counterclockwise direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These, and other features and advantages, will become appreciated as the same becomes better understood with reference to the specification, claims and drawings wherein: 
       FIG. 1  is a partial section view of a device according to the prior art illustrating the feed of rocks therethrough; 
       FIG. 2  is a top view of a portion of the device of  FIG. 1  illustrating the adjustment of the relative positions for the crushing surfaces according to the prior art; 
       FIG. 3A  is a top view of the second rotor according to the prior art; 
       FIG. 3B  is a section view of the top of the second rotor according to prior art taken along line  3 B— 3 B of  FIG. 3A ; 
       FIG. 4A  is a plan view of a spacer ring according to the prior art for the second rotor; 
       FIG. 4B  is a section view of the spacer ring for the second rotor according to the prior art taken along line  4 B— 4 B of  FIG. 4A ; 
       FIG. 5A  is a plan view of the crushing ring for the second rotor according to the prior art; 
       FIG. 5B  is a section view of the crushing ring for the second rotor according to the prior art taken along line  5 B— 5 B of  FIG. 5A ; 
       FIG. 6  is a top perspective view of the first rotor crushing surface according to the prior art; 
       FIG. 7  is a plan view of the top surface of first rotor according to the prior art; 
       FIG. 8  is a top plan view of a further embodiment of the second rotor according to the prior art; 
       FIG. 8A  is a partial section view of the second rotor according to the prior art of  FIG. 8  taken along line  8 A— 8 A of  FIG. 8 ; 
       FIG. 9  is a partial section view of the device according to the prior art incorporating the second rotor of  FIG. 8 ; 
       FIG. 10  is a side section view of a further embodiment of a crusher according to the prior art; 
       FIG. 11  is a top view of the top plate and first rotor according to the the prior art and the embodiment of  FIG. 10 ; 
       FIG. 12  is a top view of the first crushing surface and shoes of the prior art and to the embodiment of  FIG. 10 ; and 
       FIGS. 13A-D  show several embodiments of the underside of the top rotor and its plates according to the present invention; 
       FIG. 14  shows an end view of a plate for the second rotor, channels and the nip between the first and second crushing surfaces; 
       FIGS. 15A and B  show a plan and end view of a second rotor crushing plate according to the present invention  FIGS. 16A-D  show several embodiments of the underside of the top rotor and its plates according to the present invention; 
       FIG. 17  shows an end view of a plate for the second rotor, channels and the nip between the first and second crushing surfaces; and 
       FIGS. 18A and B  show a plan and end view of a second rotor crushing plate according to the present invention. 
   

   DESCRIPTION 
   Turning to the drawings,  FIG. 1  shows a device  10  according to the prior art. The device  10  includes a closed housing  12  adapted to contain the components as hereinafter described. At the top the housing  12  there is a feed port  14  which may have a funnel  16  for feeding of rocks  18  into the housing  12  for crushing thereof. At the lower portion of the housing is a discharge (not shown) from which the crushed material  20  falls for collection thereof. 
   The housing  12  is supported above the ground on a stand  22  including a plurality of legs  24  to raise the housing  12  above the ground for collection of the crushed material  20  from the device  10 . 
   With reference to  FIGS. 1 ,  6  and  7 , the device  10  includes a first rotor  26  mounted on a shaft  28  which is journaled for rotation about an axis A. Preferably, the housing  12  is cylindrical and is arranged coaxial with the shaft  28 . The first rotor  26  is circular, flat having a diameter to locate the perimeter  30  inboard of the housing  12  to provide an annular space  32  for the crushed material  20  to fall to the bottom of the housing  12  to be discharged therefrom. As shown in the drawings, the first rotor  26  has a generally planar first crushing surface  34  against which the rocks  18  are crushed in a manner to be described below. As illustrated in  FIGS. 6 and 7 , the first crushing surface  34  may include a plurality of shoes  36  tapered to define a directing surface  38  angled into the direction of rotation of the first rotor  26  and sloping outwardly and downwardly to merge with the planar first crushing surface  34 . The shoes  36 , and more particularly the directing surfaces  38  thereof, are adapted, when the first rotor  26  is rotated in a counter-clockwise direction as shown in  FIGS. 6 and 7 , to engage and urge the rocks outwardly in combination with centrifugal forces imposed on the rocks as hereinafter described. The first crushing surface  34  may be simply flat as well. 
   Returning to  FIG. 1 , the first rotor  26  is journaled to the housing  12  for rotation about axis A. To drive the first rotor  26 , a first motor  40  is provided and is coupled by drive means such as a chain  42  meshing with a sprocket  44  to rotate the shaft  28  of the first rotor  26  about axis A. Preferably the drive means encompassed by the first motor  40 , chain  42  and sprocket  44  rotates the shaft  28  at approximately 1,760 rpm. However, the first motor  40  could be variable speed in order to alter the speed of rotation of the first rotor. Further, depending upon the diameter of the rotors, the speed may be increased or decreased. 
   To cooperate with the first rotor  26 , the device  10  includes a second rotor  46  having an annular, conical ring  48  defining a second crushing surface  50  ( FIG. 5B ) adapted to be spaced from the first crushing surface  34  to define a nip  52  for crushing of the rocks  18 . 
   The second rotor  46 , as shown in  FIGS. 5A ,  5 B, is defined, in part, by an annular conical ring  48  which defines a conical second crushing surface  50  adapted to cooperate with the first crushing surface  34  to define the crushing nip  52 . The annular conical ring  48  including the second crushing surface  50  is coupled to an annular spacing ring  54  as shown in  FIGS. 1 ,  4 A and  4 B which is in turn secured to a generally closed, circular top plate  56  shown in  FIGS. 3A ,  3 B. The outside perimeters of the annular conical ring  48 , spacing ring and top plate  56  are of equal outside diameter and are concentrically aligned along a second axis B. The annular space defined by the spacing ring  54  and annular concentric ring  48  and as covered by the top plate  56  defines a crushing chamber  58  adapted to receive rocks  18  for crushing thereof. 
   To provide for rotation, the second rotor  46  includes a shaft  60  aligned with the second axis B and secured at one end to the top plate  56 , the other end extending from the housing  12  as shown in FIG.  1 . As will be described below, the shaft  60  is adapted to be rotated about the second axis B and can be vertically and horizontally displaced, with reference to  FIG. 1 , to alter the size of the nip  52  and provide, if desired, an offset between the first and second axises A and B. 
   With reference to  FIGS. 1 ,  3 A and  3 B, the top plate  56  includes one or more feed openings  62  disposed radially from the second axis B and is best shown in  FIG. 1  from the shaft  60 . Rocks  18  fed into the feed port  14  are in turn admitted through the feed openings  62  into the conical crushing chamber  58  for crushing thereof. While the feed openings  62  may simply be openings in the top plate  56 , the top plate  56  may include a plurality of shoulders  64  each adapted to urge rocks  18  through the feed openings  62  in response to rotation of the second rotor  56 . Accordingly, the shoulders  64  may be embodied as tapered scoops  66  each having a mouth  68  directed into the direction of rotation of the second rotor  46 , the scoops  66  tapering from the mouth  68  to the feed opening  62 . Accordingly, and in response to rotation of the second rotor  46 , the scoops  66  direct rocks into their respective feed openings  62  and therethrough into the crushing chamber  58 . 
   Also secured to the top plate  56  is a cylindrical bin  70  aligned coaxially with the second axis B and adapted to rotate with the second rotor  46 . Thus it can be appreciated from  FIG. 1 , rocks  18  fed into the feed port  14  fall into the bin  70  as it rotates with the second rotor  46  whereupon the rocks  18  are fed through the feed openings  62  into the crushing chamber  58 . 
   To cooperate with the bin  70  to confine the rocks therein, the housing  12  includes a fixed, cylindrical skirt  72  projecting downwardly to overlap the top of the bin  70  to prevent rocks  18  from being ejected from the rotating bin  70 . 
   To support the second rotor  46  for rotation thereof, the device  10  includes a support carriage  74  movably mounted to the housing  12 . To support the support carriage  74 , the housing mounts one or more pillars  76  in a position to upstand from the housing  12 . The support carriage  76  is, in turn, movably mounted to the pillars  76  for vertical motion along the second axis B and for motion transverse to the second axis B. Each of the pillars  76  is internally threaded to receive a vertical adjustment bolt  78  which in turn mounts the support carriage  76 . Accordingly, rotation of the vertical adjustment bolt  78  displaces the support carriage  74  and the shaft  60  journaled thereby vertically which in turn adjusts the spacing of the nip  52 . 
   The support carriage  74  has a frame  80  which is in turn mounted to the vertical adjustment bolt  78 . 
   Disposed within the support carriage  74  are bearings  82   a, b  which journal the shaft  60  for rotation about axis B. The bearings  82   a, b  are in turn mounted to a support panel  84 . The panel  84  includes a plurality of threaded sleeves  86  which are likewise supported on the vertical support pillars  76 . Offset adjustment bolts  88  are in turn disposed between the frame  80  and threaded sleeves  86 . Accordingly, rotation of the offset adjustment bolts  88  displaces the support carriage  74 , its frame  80  and the journaled shaft  60  to displace the axis B relative to the axis A. For example, the offset position of the axis B may be adjusted to be collinear with the first axis A or may be offset as shown in FIG.  1 . The offset provided between the axes A, B induces a radial component to the centrifugal forces induced by rotation of the first and second rotors  34 ,  46  and the rolling or scrubbing forces induced by the relative rotation between the first and second rotors  34 ,  50 . It has been found that for certain types of rocks and the desired output, that an offset can advantageously crush the rocks  18 . Alternatively, the axes A and B may be aligned. 
   To rotate the shaft  60 , the support carriage  74  also mounts a motor  90  coupled to the shaft  64  rotation as by a chain  92  and sprocket  94 . The motor  90 , like the first motor  40 , may be variable speed and adapted to, for example, rotate the shaft  60  and second rotor  46  at between 60 and 180 rpm. 
   With reference to  FIGS. 1 ,  6  and  7 , the first rotor  34  is rotated in a counterclockwise direction whereas the second rotor  46  is rotated in a clockwise direction to provide a maximum of the relative speeds between the first and second crushing surfaces  34 ,  50 . The first rotor  26  may not include the shoes  36  and the first motor  40  may be reversible whereby the direction as well as the relative speeds between the rotation of the first and second rotors  34 ,  50  may be altered. That is, the first rotor  26  may be rotated in the same clockwise direction as the second rotor  46  or in a counter-direction. 
   With the components of the device  10  described above, its operation will now be set forth. 
   By adjusting the vertical adjustment bolt  78 , the space at the nip  52  may be adjusted taking into account several factors. One factor is that the space at the entrance  96  of the nip  96  must be sufficiently large to accept the largest size of rock  18  fed into the device  10 . The second consideration is that at the discharge  98  of the nip  50 , the spacing between the first and second crushing surfaces  34 ,  50  can be no greater than the maximum size of crushed material  20  to be discharged from the device  10 . That is, if chips having a size of approximately one-half inch are desired, the first and second rotors  26 ,  46  should be adjusted such that the discharge  98  of the nip  52  is approximately one-half inch. If crushed sand is desired, then the discharge  98  should be made smaller to adequately crush the rocks  18  into the smaller size. It is to be understood, depending upon the nature of the rocks fed into the device  10  that the angle of the annular, conical ring  48  defining the second crushing surface  50  may be altered so as to receive the rocks  18 . It has been found that an angle formed with the first crushing surface  34  of approximately 9° to 10° provides for satisfactory crushing of the rocks. 
   After the nip  52  has been adjusted, the offset between the first and second axis A, B is selected and set. Preferably the maximum offset permitted is only to the degree that the perimeter of the second rotor  46  aligns with the perimeter of the first rotor  40  as shown in FIG.  1 . Thereafter, the first and second rotors  26 ,  46  are engaged by their first and second motors  40 ,  90  and rotation is begun. When the first and second rotors  26 ,  46  have reached their speeds, rocks  18  are fed into the feed port  14  whereupon they fall into the bin  70 . Centrifugal force caused by rotation of the second rotor  46  urges the rocks  18  to the outside of the bin  70 . Gravity urges the rocks downwardly in the bin to be received into the scoops  66  and feed openings  62  and into the crushing chamber  58 . The centrifugal force on the rocks  18  in the crushing chamber, along with any axial loading induced by the scoops  66  and any forces imposed by the directing surface  38  on the shoes  36  urge the rocks  18  from the crushing chamber  38  through the annular nip  52  for crushing between the first and second crushing surfaces  34 ,  50 . As stated above, the rocks are crushed due to the loads of the first and second crushing surfaces  34 ,  50  imposed due to the centrifugal force on the rocks  18 , the force induced by the scoops  66  and directing surfaces  38  as well as the circumferential buffing or rolling action caused by the relative rotation between the first and second rotors  34 ,  46 . The pinching between the first and second crushing surfaces  34 ,  50  created by the nip  52  crushes the rocks  18  into the crushed material  20 . The crushed material  20 , induced by centrifugal force, is ejected outwardly to the housing  12  where it falls by gravity for discharge therefrom. 
   Turning to  FIGS. 8 through 9 , a further embodiment according to the prior art is shown and particularly pertinent to the present invention. Like components bear the same reference numerals. 
   According to this embodiment, the second rotor  46 ′ includes a hexagonal top plate  56 ′ defining six depending wings  100  which extend downwardly at an angle of between 9° and 10° from a circular and planar center  102 . The perimeter of the circular center  102  corresponds with the diameter of the bin  70  to define the bottom thereof. Scoops  66  may be provided for the second rotor  46 ′. 
   To define the second crushing surface  50 ′, the second rotor  46 ′ includes secured to each of the wings  100  replaceable crushing plates  104  which are adapted to conform to the overall hexagonal shape of the second rotor  46 ′. Fasteners  106  secure each of the crushing plates  104  to the corresponding wings  100  and accordingly it is to be understood that by removing the fasteners  106 , the crushing plates  104  can be replaced for the second rotor  46 ′. Each of the crushing plates  104  is secured to their corresponding wings  100  to depend again, preferably, an angle of between 9° to 10° relative to the first crushing surface  34 . Accordingly, it is to be understood that the perimeter of the second rotor  46 ′ is of a varying radius or diameter from axis A and defines a non-circular nip  52 ′ for the device  10 . As is also to be understood, upon rotation of the shaft  60 , and by virtue of the variable perimeter of the second rotor  46 ′, that rocks trapped in the nip  52 ′ will be urged to move, relative to the perimeter of the rotors, radially inwardly and outwardly as the second rotor  46 ′ rotates. Furthermore, the angles defined at the joinder of adjacent crushing plates  104  act substantially as a funnel to funnel rocks between the crushing plates  104  of the second crushing surface  50 ′ for crushing thereof. It has been found that by using the hexagonal second rotor  46 ′ as shown in  FIG. 8 , efficient crushing of rock  18  is obtained. 
   With reference to  FIGS. 10-12  a further embodiment of a crusher according to the prior art is shown. According to this embodiment a funnel  16  is provided on the housing  12  to direct rocks fed into the housing to a feed port  14 ′. 
   The feed port  14 ′ directs the rock into the conical crushing chamber  58 ′ defined between a second rotor  46 ′, which is preferably fixed but may be free wheeling or driven for rotation, and a rotatable first rotor  26 . As with the previous embodiment, the second rotor  46 ′ has radially projecting wings each of which mounts a crushing plate  104 . The crushing plates  104  may each consist of single plate or be fashioned from a plurality of sub-plates  108  secured to the wing by fasteners  106 . As shown, the second rotor  46 ′ and crushing plates  104  define a hexagonal second crushing surface  50 ′ and nip  52  between the crushing plates  104  and the first crushing surface  34 . The crushing plates  104  are mated at adjoining sides to provide a continuous, hexagonal, second crushing surface  50 ′. 
   As can be appreciated the crushing plates  104  are substantially planar and thus can easily be manufactured and replaced. At the second crushing surface  50 ′ the fasteners  106  are recessed to prevent damage thereto. 
   The first rotor  26  is driven by a first motor  40  (not shown in  FIGS. 10-12 ) for rotation. Supporting struts  110  are coupled between the first rotor  26  and a shaft plate  112  which is, in turn, coupled to the first motor, provides for the rotation of the first rotor  26 . 
   To direct the rock fed into the crushing chamber  58  the first rotor  26  includes a plurality of shoes  36 ′ as shown in FIG.  12 . Each shoe  36 ′ has, in plan view, an arcuate leading edge  116  which also slopes downwardly toward the periphery of the second rotor  46 ′, inside out as shown in  FIG. 10. A  circular fastening plate  120  is adapted to secure the shoes  36 ′ to the first rotor  26 . Each shoe  36 ′ urges the rocks outwardly into the nip  52  between the first and second rotors  26 ,  46 ′ and the leading edge  116  in cooperation with the second rotor  46 ′ and the crushing plates  104  thereof provides a varying nip  52  to crush the rocks. 
   The hexagonal shape of the second crushing surface  50 ′ and nip  52  provide for a nip  52  whose position varies radially with respect to the axis of the first rotor  26 . Thus when the first rotor  26  is rotated the rocks are subject to a radial scrubbing action as a variable radial distance to the nip  52  is provided by the polygonal shape of the second crushing surface  50 ′. In that the crushing plates  104  are angled downwardly to the nip  52 , a further compaction force is imposed on the rocks. 
   Still further the forces imposed by the shoes  36  along with centrifugal forces impose a radial force upon the rocks to direct them into the nip  52 . The aforesaid forces contribute to the efficient crushing of the rocks. 
   Further the sloping of the leading edges  116  of the shoes  36  provide with the second crushing surface  50 ′ a taper to the nip  52  to crush rocks. 
   With reference to  FIG. 10 , the space defined by the nip  52  may be adjusted by adjusting struts  200 . Use of these struts  200  raises the second rotor  46 ′ relative to the first rotor  26  to adjust the nip  52  to the desired spacing. 
   To control dust, spry nozzles  202  may be provided about the periphery of the nip  52 . 
   It is to be understood that while the second rotor  46 ′ may be circular or hexagonal as described above, it could also be triangular, square or oblong to provide a variable radius to induce the rocks to move inwardly and outwardly for crushing thereof. 
   Turning to  FIGS. 13A-D  several embodiments of second rotor  500  and second crushing surface  50  according to the present invention are shown. With reference to  FIG. 13A , the second rotor  500  includes a plurality of crushing plates  502  secured to wings  100  ( FIG. 9 ) by fasteners  106 . As shown, the shape of the second rotor  500  and plates  502  may be polygonal such as defining a hexagon. 
   To enhance crushing and agitation of the material being crushed in advance of entry into the nip, each plate  502  may include a plurality of protuberances or projections defined as a triangular ridge  508  formed on the plate  502  by a triangular pocket  510  and side recesses  512   a, b.    
   With reference to  FIG. 13B , each plate  502  is seen to include the protuberances as radially extending ridges  514 . In  FIG. 13C , the protuberances are embodied as patterns of studs  516 .  FIG. 13D  shows a side view of a plate  502  and its taper to the nip  52  as well as the openings for attaching the plate  502  by fasteners  106 . 
   It is believed that the protuberances enhance crushing by agitating and providing initial crushing and abrasive action on the material in advance to the material entering the nip  52  between the first and second crushing surfaces. Further the protuberances are believed to urge the material to the nip  52 . 
   The plates  502  are arranged to angle and converge toward the first rotor at the nip  52 . 
   With reference to  FIGS. 13B and 14 , to provide ports for additional ejection of the crushed material through the nip  52 , the edges of the plates  502  defining the second crushing surface  50  includes a plurality of radial channels  516  which extend through the nip  52 . Preferably the channels  516  have a longitudinal dimension to extend into and merge with the crushing surfaces of the plates  502  and a lateral dimension comparable with the spacing of the nip  52 . Crushed fines in the crushing camber and proximate the nip  52  are ejected from the crusher through the nip  52  and channels  516 . Further, the side edges of the channels  516  provide further abrasion on the material for crushing thereof. 
   The channels  516  may be provided on the second rotor  500 , first rotor  26  or a combination thereof. Further the channels  516  may be provided in addition to the protuberances as suggested in FIG.  13 B. 
   Turning to  FIGS. 15A and B , there is shown a further embodiment of a plate  502  according to the present invention. According to this embodiment, the face of the plate  502  is presented as areas  600   a-c  having different configurations. In area  600   a  there are provided a plurality of projections  602  which are angled relative to a radial C. These projections are elongated and are tapered outwardly from the face of the plate  502  as suggested in FIG.  15 B. As is also shown in  FIG. 15A  the projections  602  are oppositely angled with respect to the axis C. 
   Area  600   b  includes a plurality of projecting nobs  604  which also project form the face of the plate  502 . Area  600   c  includes a plurality of channels  516  oppositely angled with respect to the axis C and disposed to extend through the nip  52 . Preferably, the angling of the channels is such that, with reference to the channels  516  to the right of  FIG. 15A  would be angled into the direction of counterclockwise rotation of the second rotor  46  whereas those on the left side are angled into the direction of clockwise rotation. Thus, those channels  516  directed for counterclockwise rotation would be disposed to offer primary ejection of the crushed material in that they are directed into the direction of rotation. Conversely, those channels disposed for clockwise rotation would offer the primary ejection for crushed material when the second rotor  46  is rotated in a clockwise rotation. 
   Further, according to the embodiment of  FIG. 15A , B the second rotor  56  (and first rotor  26 , may be rotated in both clockwise and counterclockwise directions. By occasionally reversing rotation, it is believed that wear can be more evenly distributed to the plates and crushing surfaces. The angling of the projections  602  and channels  516  accommodates the reversing of rotation. 
   The channels  516  may also taper in increase in depth and width into the face toward the perimeter thereof (FIG.  15 B). 
   Holes  606  through the plate  502  provide for connection to the wings by suitable fasteners as described above. 
   Turning to  FIGS. 16A-D  several embodiments of first rotor  700  and first crushing surface  70  according to the present invention are shown. With reference to  FIG. 16A , the first rotor  700  includes a plurality of crushing plates  702  secured to wings  100  ( FIG. 9 ) by fasteners  106 . As shown, the shape of the first rotor  700  and plates  702  may be polygonal such as defining a hexagon. 
   To enhance crushing and agitation of the material being crushed in advance of entry into the nip, each plate  702  may include a plurality of protuberances or projections defined as a triangular ridge  708  formed on the plate  702  by a triangular pocket  710  and side recesses  712   a, b.    
   With reference to  FIG. 16B , each plate  702  is seen to include the protuberances as radially extending ridges  714 . In  FIG. 16C , the protuberances are embodied as patterns of studs  716 .  FIG. 16D  shows a side view of a plate  702  and its taper to the nip  52  as well as the openings for attaching the plate  702  by fasteners  106 . 
   It is believed that the protuberances enhance crushing by agitating and providing initial crushing and abrasive action on the material in advance to the material entering the nip  52  between the first and second crushing surfaces. Further the protuberances are believed to urge the material to the nip  52 . 
   The plates  502  are arranged to angle and converge toward the first rotor at the nip  52 . 
   With reference to  FIGS. 16B and 17 , to provide ports for additional ejection of the crushed material through the nip  52 , the edges of the plates  702  defining the first crushing surface  50  includes a plurality of radial channels  716  which extend through the nip  52 . Preferably the channels  716  have a longitudinal dimension to extend into and merge with the crushing surfaces of the plates  702  and a lateral dimension comparable with the spacing of the nip  52 . Crushed fines in the crushing camber and proximate the nip  52  are ejected from the crusher through the nip  52  and channels  716 . Further, the side edges of the channels  716  provide further abrasion on the material for crushing thereof. 
   The channels  716  may be provided on the second rotor  500 , first rotor  700  or a combination thereof. Further the channels  716  may be provided in addition to the protuberances as suggested in FIG.  16 B. 
   Turning to  FIGS. 18A and B , there is shown a further embodiment of a plate  702  according to the present invention. According to this embodiment, the face of the plate  702  is presented as areas  800   a-c  having different configurations. In area  800   a  there are provided a plurality of projections  802  which are angled relative to a radius C. These projections are elongated and are tapered outwardly from the face of the plate  702  as suggested in FIG.  18 B. As is also shown in  FIG. 18A  the projections  802  are oppositely angled with respect to the axis C. 
   Area  800   b  includes a plurality of projecting nobs  804  which also project form the face of the plate  702 . Area  800   c  includes a plurality of channels  716  oppositely angled with respect to the axis C and disposed to extend through the nip  52 . Preferably, the angling of the channels is such that, with reference to the channels  716  to the right of  FIG. 18A  would be angled into the direction of counterclockwise rotation of the first rotor  46  whereas those on the left side are angled into the direction of clockwise rotation. Thus, those channels  716  directed for counterclockwise rotation would be disposed to offer primary ejection of the crushed material in that they are directed into the direction of rotation. Conversely, those channels disposed for clockwise rotation would offer the primary ejection for crushed material when the first rotor  46  is rotated in a clockwise rotation. 
   Further, according to the embodiment of  FIG. 18A and B  the second rotor  500  and first rotor  700 , may be rotated in both clockwise and counterclockwise directions. By occasionally reversing rotation, it is believed that wear can be more evenly distributed to the plates and crushing surfaces. The angling of the projections  802  and channels  716  accommodates the reversing of rotation. 
   The channels  716  may also taper in increase in depth and width into the face toward the perimeter thereof (FIG.  18 B). 
   Holes  806  through the plate  702  provide for connection to the wings by suitable fasteners as described above. 
   While I have described certain embodiments of the present invention, it is to be understood that it is subject to many modifications and changes without departing from the spirit and scope of the claims. For example, the channels described herein could be disposed on the first rotor as well.