Abstract:
A grinder having an adjustable screen arrangement. The adjustable screen arrangement including two screens independently positionable in a number of positions relative to a grinding drum. Each screen further having a leading end independently positionable relative a trailing end of the screen. The adjustable screen arrangement allowing for selectively varied clearances between the screens and the grinding drum.

Description:
[0001]    This application is being filed on 30 Nov. 2011, as a PCT International Patent application in the name of Vermeer Manufacturing Company, a U.S. national corporation, applicant for the designation of all countries except the US, and John Gary Gardner and Darin Lyn Dux, citizens of the U.S., applicants for the designation of the US only, and claims priority to U.S. Provisional Patent Application Ser. No. 61/458,998, filed Dec. 1, 2010, which is incorporated herein by reference. 
     
    
     FIELD OF THE TECHNOLOGY 
       [0002]    This disclosure generally relates to grinding machines. In particular, this disclosure relates to a screen arrangement for a horizontal grinding machine, and associated methods. 
       BACKGROUND 
       [0003]    Machines, such as grinders and chippers, are used for shredding, grinding, and/or chipping a variety of material. For the purposes of this disclosure, the preferred environment in which the principles of the invention are described is that of a grinder. Horizontal grinders and tub grinders are illustrative of grinder machines, and the example of a horizontal grinder will be used herein as a preferred environment in which the present invention may be employed. References herein to a horizontal grinder, however, are not intended to be limiting. Instead, the principles of the invention are generally applicable to machines which utilize a screen in connection with reducing larger-piece material into smaller-piece material. 
         [0004]    Horizontal grinders generally include a grinding chamber and a grinding drum. The grinding drum rotates and includes hammers or blocks. Screens position material so that the material is forced into contact with the grinding drum until ground/reduced to a certain size. Once the material reduces to the certain size, the material passes through holes in the screen and exits out of the grinding chamber. 
         [0005]    The ability to grind of a variety of different material is desirable, as the usefulness of grinding or chipping different material arises in a variety of applications. For instance, waste is often ground to increased the rate of decomposition, which is useful in landfill operations; wood waste is ground to produce mulch that is useful in landscaping applications; and asphalt is ground to promote recycling efforts. 
         [0006]    Accordingly, providing a machine that can grind a variety of material, and that is easily adaptable would be advantageous. In addition, providing a machine that better accommodates for wear situations would allow operators to more effectively operate such machines. Improvement has been sought with respect to such machines, generally to better accommodate ease of use, ease of adaptability, and ease of maintenance. 
       SUMMARY 
       [0007]    One aspect of the invention relates to a horizontal grinder having an adjustable screen arrangement. The adjustable screen arrangement includes two screens that are independently positionable in any one of a number of positions relative to a grinding drum. Each screen further has a leading end that is independently positionable relative a trailing end of the screen. The adjustable screen arrangement allows an operator to selectively vary the clearances between the screens and the grinding drum. The adjustable screen arrangement also allows an operator to replace a portion of the screen area without having to replace the entire screened area, or switch the locations of a heavily worn first screen and a second screen so that grinding operation can continue. 
         [0008]    A variety of examples of desirable product features or methods are set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing various aspects of the disclosure. The aspects of the disclosure may relate to individual features as well as combinations of features, including combinations of features disclosed in separate embodiments. It is to be understood that both the foregoing general description and the following detailed description are explanatory only, and are not restrictive of the claimed invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a partial side view of a horizontal grinder having an adjustable screen arrangement in accordance with the principles disclosed. 
           [0010]      FIGS. 2-5  are perspective views of example screens that can be used in the screen arrangement of  FIG. 1 . 
           [0011]      FIG. 6  is a top plan view of an adjusting member of the screen arrangement of  FIG. 1 . 
           [0012]      FIGS. 7-11  are schematic representations of the adjusting member of  FIG. 6  illustrated in different operating positions. 
           [0013]      FIG. 12  is a partial side view of the horizontal grinder of  FIG. 1 , illustrating a mounting hole pattern formed in a side of a mill box of the grinder. 
           [0014]      FIG. 13  is a partial front elevation view of the horizontal grinder of  FIG. 1 , illustrating a portion of the screen arrangement and mill box. 
           [0015]      FIG. 14  is a partial side view of the horizontal grinder of  FIG. 1 , illustrating the arrangement of the adjusting members of the screen arrangement. 
           [0016]      FIGS. 15-18  are partial side views of the horizontal grinder of  FIG. 1 , illustrating how the screens of the screen arrangement are installed. 
           [0017]      FIG. 19  is a partial side view of the horizontal grinder of  FIG. 1 , illustrating a second embodiment of an adjusting member that can be used in the screen arrangement in accordance with the principles disclosed. 
           [0018]      FIG. 20  is an enlarged side view of the second embodiment of the adjusting member of  FIG. 19 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Reference will now be made in detail to exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0020]      FIG. 1  is a representation of a horizontal grinder  10  having an adjustable screen arrangement  12  in accordance with the principles disclosed. In the illustrated embodiment, the horizontal grinder  10  includes a mill box  14  (partially and schematically represented in  FIG. 1 ), a mill box cover  16 , a grinding drum  18 , and an anvil  30 . A feed conveyor  20  is used to move material toward the mill box  14  to a point where a feed roller (not shown) forces material into contact with the grinding drum  18 . 
         [0021]    The grinding drum  18  grinds the material to a sufficiently small size so as to fall through the screen arrangement  12 . In particular, the grinding drum includes hammers or cutters  28  mounted to the outer perimeter of the drum that impact the material as the material is fed into the mill box. In the illustrated embodiment, the grinding drum is a down-cut grinding drum. The grinding impact of the down-cut grinding drum is primarily experienced by the anvil  30 . However, once the material passes by the anvil, the material is further reduced, as necessary within the mill box  14  until small enough to pass through the screen arrangement  12 . A discharge conveyor  22  receives the ground material for transport to a desired location. 
         [0022]    The adjustable screen arrangement  12  of the present disclosure positions the material so as to be further reduced by the grinding drum  18  as needed. The screen arrangement  12  generally includes two arcuate screens; e.g., a first arcuate screen  24  and a second arcuate screen  26 . As will be understood, more than two arcuate screens can be provided in accordance with the principles disclosed. Representative examples of screens that can be used are shown in  FIGS. 2-5 . The screens  24 ( a - d ),  26 ( a - d ) illustrated in  FIGS. 2-5  have different hole configurations. The screens can be of a variety of sizes and configurations, selected by the operator to achieve a desired size and quality of ground material. 
         [0023]    Referring back to  FIG. 1 , the two arcuate screens  24 ,  26  are located adjacent to the grinding drum  18 . The grinding drum  18  rotates about a rotational axis A-A in the direction shown (see arrow A). The direction of rotation of the drum  18  has the effect of urging material between the screens  24 ,  26  and the grinding drum  18 . The forces exerted on the material by the grinding drum  18  and/or cutters  28  of the drum grind the material until small enough to drop through the screens  24 ,  26  and onto the discharge conveyor  22 . 
         [0024]    The arcuate screens  24 ,  26  each have a leading edge  34 ,  36  and a trailing edge  44 ,  46 . The trailing edge  44  of the first screen  24  abuts the leading edge  36  of the second screen  26 . The leading edge  34  of the first screen  24  abuts the anvil  30 ; the anvil  30  prevents the two screens  24 ,  26  from moving forward or moving in a clockwise direction. The trailing edge  46  of the second screen  26  abuts a shoulder  32  provided on the mill box cover  16 ; the shoulder  32  prevents the two screens  24 ,  26  from moving rearward or moving in a counter-clockwise direction. 
         [0025]    Referring still to  FIG. 1 , the adjustable screen arrangement  12  of the present disclosure also includes screen supports or support members  40 ,  42 , and a plurality of adjusting members or adjusting devices  50 . 
         [0026]    The plurality of adjusting members  50  positions each arcuate screen  24 ,  26  in the selected one of a plurality of positions relative to the grinding drum  18 . In particular, the adjusting members  50  position the screen supports  40 ,  42  so as to support the arcuate screens  24 ,  26  in a selected position relative to the grinding drum  18 . This feature permits an operator to easily adapt the horizontal grinder  10  to accommodate different types of material, or accommodate material of different sizes. That is, changing the positions of one or both screens changes the clearance between the one or both screens and the grinding drum. This allows the operator to accommodate a change in material, or to adjust the grinding characteristics of the machine if needed. 
         [0027]    Further, the screens  24 ,  26  are positionable relative to the grinding drum  18  independent of one another. That is, the first screen support  40  can be positioned to provide a larger clearance between the first screen  24  and the drum  18 , while the second screen support  42  can be positioned to have a smaller clearance between the second screen  26  and the drum  18 . This can be useful in applications where the machine&#39;s grinding characteristics require more customization. Along this same line, the adjusting members are also arranged to selectively vary the clearance between the leading edge  34 ,  36  of each screen  24 ,  26  and the grinding drum  18 , and selectively vary the clearance between the trailing edge  44 ,  46  of each screen and the grinding drum  18 . That is, the leading edge clearance of a particular screen can be adjusted relative to the trailing edge clearance of that screen. 
         [0028]    Referring now to  FIGS. 1 and 6 , the plurality of adjusting members  50  includes an adjusting cam member or cam  52 . The cam  52  pivots to adjust the position of the screen supports  40 ,  42  and accordingly the screens  24 ,  26  relative to the grinding drum  18 . Each cam  52  defines a series or plurality of arc sections  54  at one end, and a pivot point P at an opposite end. In the illustrated embodiment, the cam  52  has five arc sections  54 . 
         [0029]    Referring to  FIG. 7 , when the cam is in a first position, the screen support (e.g.,  40 , schematically represented), and accordingly the screen (e.g.,  24 ,  FIG. 1 ) are in a first position relative to the grinding drum. Referring to  FIGS. 8-11 , as the cam  52  is pivoted to second through fifth positions, the screen support (e.g.,  40 ) and screen move to second through fifth positions relative to the grinding drum (see dashed lines in  FIGS. 8-11  representing the previous position(s) of the screen support  40 ). 
         [0030]    Fasteners secure the cam  52  in the selected position. The fasteners are received within apertures  56 ,  58  ( FIG. 12 ) formed in sides  60  ( FIG. 13 ) of the mill box  14 . In the illustrated embodiment, a first fastener  62  is received within the aperture  56  having circular portions, and a second fastener  64  is received within the aperture  58  having an arcuate slot shape. The circular portions of aperture  56  can be used as reference to indicate to the operator the particular positioning of the adjusting cam member  52 . Other reference notation or indicia can be used. Referring to  FIG. 12 , slotted apertures  74  are also formed in the sides  60  of the mill box  14 . The slotted apertures  74  are used for securing the screen support  40 ,  42  to the mill box. As can be understood, the slotted configuration of the apertures  74  allows for the movement of the screen supports to the desired positions. 
         [0031]    Referring now to  FIGS. 6 and 14 , the cams  52  experience load and operational forces F from contact with the screen supports  40 ,  42 . The load and operational forces F are transferred from the contacting arc section  54  of the cam  52  to the center of the pivot point P (see  FIG. 6 ). Transfer of the forces through the center of the pivot point P is provided by the arrangement and design of the cam wherein a central radius R 1  of each contacting arc section  54  (dashed in  FIGS. 6 and 14 ) is coaxial with a central radius R 2  of the grinding drum  18  (see  FIG. 14 ). This coaxial arrangement and design exists for each arc section  54  of each cam  52  when in contact with the corresponding screen support. Because the force F is directed through the center of the pivot point P (as opposed to being offset from the pivot point), torque about the pivot point P of the cam  52  is minimized or eliminated. This arrangement and design reduces or prevents occurrences where an offset force or torque inadvertently causes an element to pivot or loosen. 
         [0032]    In addition to the adjusting cam members  52 , the plurality of adjusting members  50  also includes an adjusting set-screw member  68 . Referring again to  FIG. 1 , the adjusting set-screw member  68  is carried by the mill box cover  16 . The adjusting set-screw member  68  includes a wedge or block  70  and a set screw  72 . The set-screw member  68  allows an operator to vary the clearance between the trailing edge  46  of the second screen  26  and the grinding drum  18 . 
         [0033]    As can be understood with reference to  FIGS. 1 and 13 , each of the first screen  24  and the second screen  26  is positioned relative to the grinding drum by two pairs of adjusting members  50 ; i.e., a leading pair at both sides and adjacent to the leading edge  34 ,  36  of each screen  24 ,  26 , and a trailing pair at both sides and adjacent to the trailing edge  44 ,  46  of each screen  24 ,  26 . The two pairs of adjusting members that position the first screen  24  relative to the grinding drum are the adjusting cam members  52  that mounted to the sides  60  of the mill box  14 . The two pairs of adjusting members that position the second screen  26  relative to the grinding drum include a pair of adjusting cam members  52  that mounted to the sides  60  of the mill box  14 , and a pair of adjusting set-screw members  68  that are carried by the mill box cover  16 . 
         [0034]      FIGS. 15-18  illustrate one method of installing the screens  24 ,  26  of the disclosed screen arrangement  12 . In the one method, the first screen  24  is inserted within the mill box in a counter-clockwise direction so as to be positioned adjacent to the anvil  30  and positioned upon a corresponding first one of the screen supports  40 . The second screen  26  is then inserted within the mill box in a counter-clockwise direction so as to abut the first screen  24  and be positioned upon a corresponding second one of the screen supports  42 . The adjusting cam members  52  are adjusted so that the leading and trailing edges of the first screen  24 , and the leading edge of the second screen  26  are positioned as needed relative to the grinding drum  18 . The mill box cover  16  is closed and the adjusting set-screw member  68  is adjusted so that the trailing edge of the second screen  26  is positioned as needed relative to the grinding drum  18 . 
         [0035]    As previously described, the present screen arrangement permits an operator to vary the clearance between the two screens and the grinding drum to accommodate different types of material or to accommodate material of a different size. In addition, the present screen arrangement  12  provides for ease of maintenance. With reference still to  FIGS. 15-18 , the method of replacing one or more screens is just as quick and easy as installing the screens. To replace one or both screens, an operator need only open the mill box cover  16  and slide the screens in and out of place. Providing a two-screen arrangement further permits replacement of only one screen, in contrast to having to replace an entire screened area. For example, a screen having the heavier wear (typically the first screen which receives greater impact forces) can be replaced without having to replace the second screen, which saves on parts &amp; material costs. In the alternative, when one screen experiences heavier wear, the positions of the two screens about the circumference of the drum can be switched so that grinding operation can continue with the lesser worn screen now receiving the greater impact forces. 
         [0036]    Referring now to  FIGS. 19 and 20 , a second embodiment of an adjusting cam member  152  is illustrated. The adjusting cam member  152  can be used in the screen arrangement  12  in accordance with the principles previously disclosed. In this second embodiment and similar to the first cam embodiment, each cam  152  defines a series or plurality of arc sections at one end (see the five arc sections identified by arrows  1 - 5  in  FIG. 19 ), and a pivot point P at an opposite end. As previously described, load and operational forces are transferred from the contacting arc section of the cam  152  to the center of the pivot point P wherein torque about the pivot point P of the cam  152  is minimized or eliminated. The other features set forth in the above description concerning the first embodiment of adjusting cam members, the screen arrangement, and the horizontal grinder apply to this second embodiment of adjusting cam members. 
         [0037]    The above specification provides a complete description of the present invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, certain aspects of the invention reside in the claims hereinafter appended.