Abstract:
A grinder having with a rotor and fan assembly mounted in a housing having one or more of the following features: Cutting shaft and fan shaft concentric and rotated by separate motors, housing formed in two sections with a line of division passing through the axis of rotation and mounted on rollers, ping pong shaped cutting hammers, deflectors attached to the inside of the housing and to a deflector assembly on the outside of the housing. The deflectors movable vertically and horizontally with first and second motion controllers for adjusting the spacing between the cutting hammers and the deflectors. A programmable logic controller for independently controlling the speed at which the cutting shaft and fan shaft are rotated and the spacing between the cutting hammers and the deflectors to produce a desired particle size reduction for a selected material.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a grinder with a generally vertical, rotatable first shaft having at least one set of cutter discs driven thereby and a fan assembly mounted below the cutter blades on a second vertical, rotatable second shaft in position to receive output from the cutter blades. The first and second shafts are driven by separate motors. Other features will be apparent in view of the disclosure which follows. 
         [0003]    2. Brief Description of the Prior Art 
         [0004]    Grinders, shredders or mills are well known devices for reducing the particle size of a material. For example, U.S. Pat. No. 5,192,029 to Harris, U.S. Pat. No. 5,680,994 to Eide et al. and U.S. Pat. No. 7,950,601 to Watts disclose mills for grinding garbage. Each of these mills includes a rotor mounted in a octagonal housing. The rotor includes a generally vertical shaft and a plurality of blades mounted on the shaft. Garbage is admitted into the housing through an inlet near the top of the housing and is impacted by the blades of the rotor. Material of a reduced particle size is removed from the mill through an outlet near the bottom of the housing. 
         [0005]    The mill of Eide et al. &#39;994 and Watts &#39;601 further includes a fan or impeller which is mounted on the same shaft as the cutter discs. The fan is intended to create airflow which acts to move material through the mill and to expel it from the outlet. The airflow from the fan also acts to remove moisture from the material as it is being ground. Since different materials and different grinding conditions produce different moisture levels in the material, it is advantageous if the rate of airflow can be adjusted. 
         [0006]    In Watts &#39;601 the airflow can be adjusted by repositioning the fan blades on the fan disc. This, however, requires opening up the grinder to access the fan blades which interferes with production throughput. In addition, the newly positioned blades may not produce the desired airflow and the process may need to be repeated until an acceptable result is achieved. In addition as mentioned above, different materials have different moisture levels and with the Watts &#39;601 grinder it is not possible to adjust the airflow dynamically. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In view of the above, it is an object of the present invention to provide a grinder wherein the airflow can be adjusted dynamically without disassembling the grinder. Another major object is to provide a grinder wherein the spacing between the cutter disks and the anvils may be adjusted without disassembling the grinder. Other objects and features of the invention will be in part apparent from the following disclosure and in part pointed out. 
         [0008]    In accordance with the invention, a grinder of the general type discussed above includes a separate fan assembly. In an embodiment of the invention the fan assembly includes a fan disk with fan blades attached horizontally, angularly and outwardly from the fan disk toward the walls of side wear plates on the inside of the grinder. In some instances, the fan disk is mounted on a separate shaft concentric with the cutting shaft. The separate fan shaft with a separate motor allows for increasing or decreasing airflow through the grinder without opening up the grinder housing. For example, when the shaft for the fan assembly is connected to a motor rated at 3,600 rpm and the main cutting shaft is connected to a motor rated at 1,800 rpm, the two shaft speeds may be separately adjusted through an electronic interface. Using that interface, throughput may be maximized by adjusting the speed of either or both shafts. 
         [0009]    In other embodiments, the grinder includes an automated angle deflector height adjustment. A Further automated enhancement includes a horizontal pneumatic two position actuator. When energized with a solenoid the horizontal positioner supplies 150 pound pressure to the deflectors to lock them against the interior wear plates. When the horizontal actuator is de-energized the actuator spring returns and the push rod moves the deflectors away from the interior walls. The vertical positioner can then move the deflectors to the desired height along the inside walls. The deflectors are therefore alternately unlocked to vertically position the anvil and then locked to secure the deflector to the interior wall for cutting. Previously, grinders had a mechanical height adjustment that required the removal or addition of washers between externally fixed mounting plates attached to vertically moveable deflectors on the exterior side plates to position an interior deflector up or down to produce a variable cut. This adjustment like adjusting the fan blades in the Watts &#39;601 grinder cannot be done on the fly. In the subject embodiment of the present invention, a motion controller with position feedback is attached to an external bracket that moves an internal deflector. By adjusting the gap between the cutting hammers and the deflectors, the grinder may be preset for grinding wood, plastic, municipal solid waste, etc. to produce the desired particle size reduction. The appropriate conditions for each material may be stored in a processor as a recipe. 
         [0010]    Further embodiments of the present invention include an improved automated control system including a processor (e.g., programmable logic controller (PLC)) and an electronic interface (e.g., human machine interface (HMI) touchscreen). The control system may be used to set the speed of the grinder main cutting shaft motor and then monitor the grinder shaft load in order to regulate the speed of in-feed and discharge conveyors. The cutting height between the cutting hammers and the deflectors may be selectable at the HMI touchscreen monitor as well as adjusting the separate fan assembly motor. 
         [0011]    Other embodiments of the present invention make use of improved metallurgy. Previously the Watts &#39;601 grinder, for example, was fabricated entirely of A36 carbon steel. Better performance is achieved by constructing the cutting hammers of AR400 steel alloy and constructing the cutting disks of A514 steel alloy. The cutting hammers formed of AR400 steel alloy withstand the harsh impact environment of the in-feed material and the cutting disks formed of A514 steel alloy do not deflect downward at high speeds, thereby reducing material stress and metal fatigue, and thus changing the gap between the cutting hammers and the deflectors. In one embodiment, the pins that attached the hammers to the cutter discs and/or the main cutting shaft are made of 4340 steel alloy which allows for higher speed operation. Still further improvements include forming removable interior wear plates as well as the cutting hammers from AR400 steel alloy to improve and increase wear life. 
         [0012]    In an embodiment of the invention, the grinder housing is polygonal and formed in sections with flanges which are bolted together. To access the rotor the sections are mounted on rollers installed on a shell roller track by means of which the sections may be parted when the flanges are unbolted. 
         [0013]    The invention partially summarized above comprises the constructions hereinafter described. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0014]    In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated, corresponding reference characters refer to corresponding parts throughout the several views of the drawings in which: 
           [0015]      FIG. 1  is a perspective view of a grinder in accordance with the present invention mounted on a stand; 
           [0016]      FIG. 2  is a perspective view with shell assembly separated; 
           [0017]      FIG. 3  is a perspective view of the grinder separated from the stand; 
           [0018]      FIG. 4  is a top plan view of the grinder; 
           [0019]      FIG. 5  is a sectional view taken along the plane of  5 - 5  in  FIG. 4 ; 
           [0020]      FIG. 5A  is a detail on an enlarged scale taken along the line  5 A- 5 A in  FIG. 5 ; 
           [0021]      FIG. 6  is a sectional view taken along the plane of  6 - 6  in  FIG. 5 ; 
           [0022]      FIG. 6A  is an enlarged view taken along the line  6 A- 6 A in  FIG. 6 ; 
           [0023]      FIG. 7  is a perspective view of the concentric fan assembly on an enlarged scale; 
           [0024]      FIG. 8  is a perspective view of the main cutting shaft and the concentric fan shaft assemblies; 
           [0025]      FIG. 9  is a side elevation of an exterior sidewall panel showing automated motion control of a deflector; 
           [0026]      FIG. 10  is a inside perspective view of the housing showing three ranks of deflectors; 
           [0027]      FIG. 11  is side elevation of the grinder in accordance with the present invention showing the general alignment of the main shaft motor/drive sheave with the main shaft/driven sheave and the position of the concentric shaft motor; 
           [0028]      FIG. 12  is a side elevation showing the complete deflector assembly with motorized vertical position controller; 
           [0029]      FIG. 13   is  side elevation of the inside of one of the grinder sections; 
           [0030]      FIG. 13A  is a sectional view taken along the plane of  13 A- 13 A in  FIG. 13 ; 
           [0031]      FIG. 13B  is a detail on an enlarged scale taken along the line of  13 B- 13 B in  FIG. 13A ; and, 
           [0032]      FIG. 14  is a perspective view of a programmable logic controller and a human machine interface 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. For purposes of description herein, the terms “upper,” “lower,” “left,” “rear,” “right,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0034]    Referring to the drawings more particularly by reference character, reference numeral  20  refers to a grinder in accordance with the present invention. Grinder  20  has a number of features which set it apart from Watts &#39;601 mill which is believed to be the closest prior art. Those features are combined in grinder  20  but could be separately used to improve grinders of the general type discussed in the Brief Description of the Prior Art section and are therefore regarded as separately patentable. 
         [0035]    Grinder  20  includes a rotor  22  and a fan assembly  24  ( FIG. 8 ) rotatably mounted in a housing  26 . As illustrated, housing  26  is generally hexagonal in shape but could be octagonal, decagonal or other, preferably even numbered polygonal in shape. Housing  26  includes six exterior sidewall panels  28  which may be formed of A36 carbon steel. The six exterior sidewall panels  28  are joined into two horizontally movable shell assembly sections  30 , each having three sides. Each section  30  has a shell flange  32  which extends vertically along the sides for connecting the sections together with bolts. The mating flanges  32  allow for a gasket material to be inserted forming a watertight seal. A line of division between sections  30  passes through an axis of rotation of rotor  22  (center point of rotor  22  seen in  FIG. 4 ) to permit access to rotor  22  for installation and removal. For this purpose, both sections  30  are installed on a shell roller track  208  and shell rollers  207  by means of which a section may be parted from the other section when flanges  32  are unbolted. Housing  26  has a top wall  36  and a bottom wall  38  upon which shell roller track  208  is mounted. A feed stock input chute  40  is provided in top wall  36  and a reduced material discharge chute  42  is formed in a sidewall of housing  26  just above bottom wall  38 . A chute hood  200  is mounted on feed stock input chute  40  for delivery of the feed stock into the input chute  40 . Housing also includes six vertical interior removable wear plates  44  which may be formed of AR400 steel alloy for better wearability and which line the inside of sidewall panels  28 . 
         [0036]    A main cutting shaft  46  of rotor  22  is rotatably journaled in housing  26  by a motor  48  which may be, for example, electric or hydraulic and which may be connected to main cutting shaft  46  with a sheave pulley  50 . An upper bearing  52  for main cutting shaft  46  is mounted on top wall  36 . Similarly a lower bearing  54  is below bottom wall  38  immediately under concentric fan shaft driven sheave  96 . Lower bearing  54  is supported by grinder support frame  210 . Bearings  52  and  54  may be removable angular contact bearings instead of pillow blocks to provide a cost effective method for replacing the bearings and main cutting shaft  46  may be made of 4340 alloy steel to improve performance and wear at high speed. 
         [0037]    A plurality of cutter discs  56 , illustrated as three, are mounted on main cutting shaft  46 , and denominated as discs  56   a ,  56   b  and  56   c . Mounted on each disc  56  are cutting hammers  58 . Discs  56  may be formed of A514 steel alloy which reduces the downward deflection of the discs at high speed as may occur with discs formed of other steel alloys. As illustrated, cutting hammers  58  are ping pong paddle in shape which allows for a more robust, wider end for attachment to discs  56 . For example, a 3″ hole may to drilled in cutting hammers  58  for attachment with a 3″ connection device  60  to allow for a more secure connection to cutter discs  56 . In addition, the curved paddle portion of cutting hammers  58  provides more hammer cutting surface producing more effecting cutting of the infeed material into bits. Cutting hammers  58  may be formed of AR400 steel alloy which is an improvement over the rectangular A36 steel bar stock used for the hammers in Watts &#39;601 patent. 
         [0038]    In one embodiment of grinder  20 , illustrated in the drawings, disc  56   a  is smaller in diameter than disc  56   b  and four cutting hammers  58  are provided on discs  56   a  and  56   b  while disc  56   c  is outfitted with six cutting hammers  58 . When top disc  56   a  is smaller than the second disc  56   b , infeed material drops onto the second cutter disc  56   b . This prevents the material from passing by the second disc  56   b  along interior wear plates  44  and is an improvement over the Watts &#39;601 patent where the large diameter of top disc  56   a  prevented the material from dropping on second disc  56   b  for further grinding. 
         [0039]    Mounted inside interior wear plates  44  in each section  30  of housing  26  is a deflector  62  just below each cutter disc assembly. Deflectors  62  act as anvils independent of each other and are movable away from or towards interior wear plates  44 . As best seen in  FIG. 13B  in combination with  FIG. 6A  wherein the wear plate and sidewall are omitted for purposes of clarity, deflectors  62  are positioned away from interior wear plates  44  with horizontal positioners  203  that when de-energized provide a small gap allowing vertical deflector  62  movements in vertical elongated wall slots  72  provided in exterior sidewall panels  28  and wear plates  44 . Deflectors  62  are locked into place with horizontal positioners  203  when energized to allow for a secure connection to the interior wear plates  44 . As best seen in  FIGS. 8 and 9 , each deflector  62  includes a vertical flange  64  positioned in abutment against an interior surface of the respective interior wear plate  44  and a horizontal flange  66  which extends inwardly from the respective section  30 . Deflectors  62  are positioned such that horizontal flanges  66  are each in general alignment with cutter discs  56  such that cutting hammers  58  move in closely spaced relation to the upper surface of horizontal flange  66 . As shown in  FIG. 10 , deflector  62  below second disc  56   b  has downwardly and inwardly extended leg  68  (e.g., 45 degrees) for deflecting material passing through the grinder towards third disc  56   c.    
         [0040]    The gap between horizontal flange  66  and an underside of cutting hammers  58  is critical to the size that the material is chopped and may be advantageously adjusted for the type and/or moisture content of the material passing through grinder  20 . More distance results in a larger particle size, while a shorter distance yield a smaller size particle. Deflectors  62  may therefore mounted to respective interior wear plates  44  in such a manner that the position of each deflector  62  can be fine tuned to ensure proper alignment with the respective cutter disc assembly. For the purpose of adjusting the gap as seen in  FIG. 13B  taken in combination with  FIG. 9-12 , each section of deflector  62  is supported on a plurality of spaced apart bolts  70 , illustrated as two which pass through oversized or elongated vertically aligned openings  72  provided in interior wear plates  44  and exterior sidewall panels  28 . On the outside of housing  26 , a deflector mounting bracket assembly  74  is provided on each of sidewall panels  28  in each section  30 . Holes  80  are provided in bracket assembly  74  for bolts  70  to attach the sections of deflectors  62  to bracket assembly  74 . Mounting bracket assembly  74  is supported on exterior sidewall panels  28  by vertical slide assemblies  202  that are attached to brackets  206 . Brackets  206  are attached by welding or the like to the exterior walls. Mounting bracket assembly  74  is raised or lowered vertically with a vertically extending leg  76  attached to positioner  84  such as a cylinder. Bolts  70  are welded on one end to vertical flange  64  and threaded on the other end connecting exterior mounting bracket assembly  74  with a molded washer nut  211  to deflector  62 . A sleeve bushing  80  over bolts  70  keeps the assembly of the two parts separated. Two position pneumatic actuators  203 , with spring return positioners, when electrically energized by solenoid push against vertical flange  64  of deflectors  64  and there is a small gap between vertical flanges  64  and the wear plates  44 . The cutting deflectors  52  are then locked into place for cutting after being positioned vertically. The solenoid is de-energized to move the deflectors  62  away from the inner wear plates to allow for vertical positioning of defelectors  62 . Molded washer nut  211  will extend away from the exterior walls when horizontal positioner  203  is in the energized locked position. Molded washer nut  211  is forced against exterior deflector mounting bracket assembly  74  when horizontal positioner  203  is de-energized and plunger is retracted to allow for vertical movement of bolts  70  in vertically aligned openings  72 . 
         [0041]    A motion controller  84  such as an electrically or hydraulically operated plunger attached to welded bracket  78  is provided for moving exterior brackets  74  and connected deflectors  62  up and down within the range of elongated openings  72  thereby adjusting the gap between horizontal flange  66  and cutter discs  56 . As illustrated, three motion controllers  84  in the form of a servo motor are attached to a center exterior sidewall panel  28  above bracket assembly  74  on each section  30 . A pushrod  86  from motion controller  84  is connected to bracket assembly  74  for moving the bracket and the connected deflector up or down and adjusting the distance between deflector horizontal flange  66  and the underside of cutting hammers  58  thereby controlling the chop. 
         [0042]    Fan assembly  24  is mounted below lower cutter disc  56   c . A fan shaft  88  is journaled for rotation by a second motor  90  in bearings  94 , respectively. As best seen in  FIG. 4A , fan shaft  88  and main cutting shaft  46  are concentric and fan shaft  88  is driven with a sheave pulley  96 . In other embodiments, fan shaft  88  may be mounted in discharge chute  42  parallel to main cutting shaft  46 . Bearing  94  is supported by bottom wall  38  and by a framework concentric bearing support  209 . A plurality of fan blades  104 , illustrated as four, is attached to fan shaft  88  with a direction of rotation. 
         [0043]    In use, a programmable logic controller (PLC)  106  may be used to control cutting shaft  46  speed, the vertical position of deflector horizontal flange  66 , the horizontal position of deflector  62 , fan shaft  88  speed and regulate infeed and discharge conveyors appropriately—all of which are separately controllable to best suit the material being ground. Since none of these adjustments require opening up or disassembling grinder  20 , they may be made dynamically as materials or conditions change. In addition, the PLC may store predefined cutting shaft speeds, fan shaft speeds and cutting heights for various infeed materials selectable through a human machine interface (HMI)  108  touch screen monitor. This degree of control is a major step forward over Watts &#39;601 mill where only the main cutting shaft motor speed was selectable. 
         [0044]    In the above description, numerous specific details are set forth such as examples of some embodiments, specific components, devices, methods, in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to a person of ordinary skill in the art that these specific details need not be employed, and should not be construed to limit the scope of the disclosure. In the development of any actual implementation, numerous implementation-specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints. Such a development effort might be complex and time consuming, but is nevertheless a routine undertaking of design, fabrication, and manufacture for those of ordinary skill. Hence as various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.