Abstract:
A method for reducing impact damage to a waste fragmentation machine is provided in various embodiments. In general, material that is potentially ungrindable, e.g., unacceptably dense, may be inadvertently allowed to enter into the grinding chamber within the machine where it encounters a high-speed rotor. The high-speed rotor comprises rotor teeth that impact the material to fragment or comminute it to an acceptable size. A vibration detector is placed in proximity with the rotor&#39;s bearing(s) and, after taking a daily baseline sample, monitors the fragmentation process. If the vibration level goes beyond an alert upper limit, the operator may be alerted via visual and/or audible annunciation that potentially ungrindable material may be in the grinding or fragmenting chamber. The operator may then examine the waste material and, if necessary, remove any potentially ungrindable material. Further, if the vibration level exceeds an interventional upper limit, in various embodiments the powered feed system that feeds the waste material into the grinding chamber may be stopped. Alternatively, the feed system may be reversed and/or the high-speed rotor may be disengaged. In certain embodiments, if the interventional upper limit has been exceeded, the machine may require the operator to actively intervene, e.g., entering a password, before the machine will resume fragmenting.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to a method for monitoring and analyzing the processes occurring during operation of a waste fragmentation machine to minimize damage. 
     BACKGROUND OF THE PRESENT INVENTION 
     Fragmenting machines or waste recycling machines are designed to splinter and fragment wastes under tremendous impacting forces. Operationally, waste materials are fed to a fragmenting zone or grinding chamber by power feeding means. Once the waste materials are within the fragmenting zone or grinding chamber, a powered fragmenting rotor that is rotating at high speed and comprising impacting and shearing teeth is encountered. The resulting impact results in the fragmentation and/or comminution of the waste materials to a desired particle size. Generally, the rotor rotates at about 1800-2500 r.p.m. Thus, a tremendous force is generated at the point of impact between the waste material and the impacting rotor teeth. Certain material having unacceptably high density, e.g., heavy pieces of steel, are ungrindable and may cause significant damage to the fragmenting machine, resulting in expense and machine downtime. Thus, a need exists for detecting the potentially damaging material and for preventing or minimizing such damage upon detection. 
     A wide range of methods and associated devices are currently used for monitoring performance characteristics of industrial equipment. Generally, the monitoring devices generally are placed on, or near, the equipment or points of interest thereof. Once positioned, the devices monitor certain signals generated by the equipment and the performance of the equipment is then evaluated by, inter alia, analyzing the signal data. These signals are utilized to monitor the performance of the equipment over its operating life. For example, vibration monitoring may be used to monitor the frictional energy created by the equipment&#39;s moving parts, e.g., bearings, couplings, gear mesh and the like. Low frequency vibration measurements may indicate a bearing in an advanced state of wear and potentially provide information about the root cause of the failure such as misalignment, imbalance, etc. High frequency vibration monitoring may detect such wear at an earlier stage, triggering alarms before the bearing enters a failure state due to wear and tear. High frequency vibration monitoring may also allow for maximization of preventive maintenance programs by indicating when, for example, it is necessary or desirable to grease or otherwise lubricate the subject machine components. 
     However, none of the currently described methods allow for detection of potentially ungrindable material within the grinding or fragmenting chamber of a waste fragmenting machine. Nor does any currently known waste fragmenting machine combine detection of potentially ungrindable material with additional steps to minimize any damage resulting from the impact of the rotor teeth on the potentially ungrindable material. 
     Accordingly, there remains a need for a method that limits or prevents damage to a fragmenting machine by detecting unacceptably dense material within the grinding chamber or fragmenting zone and then initiating steps to minimize any damage. The present invention addresses this need. 
     SUMMARY OF THE INVENTION 
     A method for reducing impact damage to a waste fragmentation machine is provided in various embodiments. In general, material that is potentially ungrindable, e.g., unacceptably dense, may inadvertently enter the grinding or fragmenting chamber within the machine where it encounters a high-speed rotor. The high-speed rotor comprises rotor teeth that impact the material to fragment or comminute it to an acceptable size. A vibration detector is mounted near the grinding chamber and, after taking a daily baseline sample, monitors the fragmentation process. If the vibration level goes beyond an alert upper limit, the operator may be alerted via visual and/or audible annunciation that potentially ungrindable material may be in the grinding or fragmenting chamber. The operator may elect to examine the waste material and, if necessary, remove any potentially ungrindable material. Further, if the vibration level exceeds an interventional upper limit, in various embodiments the powered feed system that feeds the waste material into the grinding chamber may be stopped. Alternatively, the feed system may be reversed and/or the high-speed rotor may be disengaged. In certain embodiments, if the interventional upper limit has been exceeded, the machine may require the operator to actively intervene, e.g., entering a password, before the machine will resume fragmenting. 
     An object of various embodiments of the invention is to provide a method for detecting potentially ungrindable material within the fragmenting chamber of a waste fragmentation machine. 
     Another object of various embodiments of the invention is to provide a method for minimizing damage resulting from detected potentially ungrindable material within the fragmenting chamber of a waste fragmentation machine. 
     Another object of various embodiments of the invention is to provide a method for monitoring vibration levels to detect potentially ungrindable material within the fragmenting chamber of a waste fragmenting machine and subsequent intervention. 
     Still another object of various embodiments of the invention is to provide a method for disengaging the powered feed system when potentially ungrindable material is detected. 
     Yet another object of various embodiments of the invention is to a method for reversing the powered feed system when potentially ungrindable material is detected. 
     Another object of various embodiments of the invention is to provide a method for disengaging the fragmenting rotor when potentially ungrindable material is detected. 
     Another object of various embodiments of the invention is to provide a method for alerting the operator via visual and/or audible annunciation of the presence of potentially ungrindable material within the fragmenting chamber of a waste fragmenting machine. 
     Yet another object of various embodiments of the invention is to provide a method for locking out all control systems until the operator intervenes, e.g., enters the correct password to restart the machine when potentially ungrindable material is detected within the fragmenting chamber of a waste fragmentation machine. 
     The foregoing objects of various embodiments of the invention will become apparent to those skilled in the art when the following detailed description of the invention is read in conjunction with the accompanying drawings and claims. Throughout the drawings, like numerals refer to similar or identical parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a waste fragmentation machine. 
         FIG. 2  is a cross sectional view of a waste fragmentation machine. 
         FIG. 3   a  is a breakaway of one embodiment of the apparatus used in the inventive method. 
         FIG. 3   b  is a block diagram of one embodiment of the apparatus used in the inventive method. 
         FIG. 4  is a flowchart illustrating one embodiment of the inventive method. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the accompanying figures, there is provided a method for monitoring the density of the waste material stream entering the grinding chamber of a waste fragmentation machine to minimize machine damage cause by material of unacceptably high density. 
       FIGS. 1 and 2  provide complementary cross-sectional views of one embodiment of a waste fragmenting machine  10 . The machine  10  is designed to splinter and fragment wastes under tremendous impacting forces. Such machine may include a frame  12  structurally sufficient to withstand the vigorous mechanical workings of machine  10 . One embodiment of the machine  10  may be powered by several electrical motors generally prefixed by M, namely M R , M D , M P , and M F . These electric motors are illustrated as equipped with suitable drive means for powering the various working components, namely the feeding, fragmenting and discharging means of machine  10 . It will be obvious to the skilled artisan, however, that the machine  10  may be powered by a variety of different power sources, e.g., internal combustion engines, diesel engines, hydraulic motors, industrial and tractor driven power take-off, etc. 
     In basic operational use in various embodiments, waste materials W may be power fed by a conveyer system to a fragmenting or grinding chamber  4  by a powered feed system  8  powered by a feed motor M F  in cooperative association with a power feed rotor drum  8 D powered by power feed motor M P . 
     Thus, one embodiment of the machine  10  may include a hopper  7  for receiving waste materials W and a continuously moving infeed conveyer  9  for feeding wastes W to the waste fragmenting or grinding chamber  4 . An infeed conveyer  9  may be suitably constructed of rigid apron sections hinged together and continuously driven about drive pulley  9 D and an idler pulley  9 E disposed at an opposing end of the conveyer  9 . The conveyer  9  may be operated at an apron speed of about 10 to about 30 feet per minute, depending upon the type of waste material W. The travel rate or speed of infeed conveyer  9  may be appropriately regulated through control of gearbox  9 G. Feed motor M F  in cooperative association with gear box  9 G, apron drive pulley  9 P, chain  9 F, and apron drive sprocket  9 D driven about feed shaft  9 S serves to drive continuous infeed conveyer  9  about feed drive pulley  9 D and idler pulley  9 E. 
     A power feed system  8  driven by motor M P  and in cooperative association with the infeed conveyer  9 , driven by motor M F , uniformly feeds and distributes bulk wastes W such as cellulose-based materials to the fragmenting or grinding chamber  100 . Power feed system  8  positions and aligns the waste W for effective fragmentation by the fragmenting rotor  40 . The power feed system  8  comprises, in one embodiment, a rotor drum  8 D equipped with projecting feeding teeth  8 A positioned for counterclockwise rotational movement about rotor drum  8 D. Drum  8 D may be driven by power feed shaft  8 S which in turn is driven by chain  8 B, drive sprocket  8 P and motor M P . 
     A rotary motor M R  serves as a power source for powering a fragmenting rotor  40  that operates within the fragmenting or grinding chamber  4 . The fragmenting and grinding are accomplished, in part, by shearing or breaking teeth  41  which rotate about a cylindrical drum  42  and exert a downwardly and radially outward, pulling and shearing action upon the waste material W as it is fed onto a striking bar  33  and sheared thereupon by the teeth  41 . The shearing teeth  41  project generally outwardly from a cylindrical rotor  42 , which is typically rotated at an operational speed of about 1800-2500 r.p.m. The fragmenting rotor  40  is driven about a power shaft  42 S, which is in turn powered by a suitable power source such as motor M R . Motor M R  is drivingly connected to power shaft pulley  42 P which drivingly rotates power shaft  42 S within power shaft bearing  42 B. The rotating teeth  41  thus create a turbulent flow of the fragmenting wastes W within the fragmenting zone  4 . 
     Initial fragmentation and impregnation of the waste feed W is, in one embodiment, accomplished within the dynamics of a fragmenting or grinding chamber  4  which may comprise a striking bar  33  and a cylindrical rotor  42  equipped with a dynamically balanced arrangement of the shearing or breaker teeth  41 . The striking bar  33  serves as a supportive anvil for shearing waste material W fed to the fragmenting zone  4 . Teeth  41  are staggered upon rotor  42  and dynamically balanced. Rotor  42 , generally operated at an operational rotational speed of about 1800-2500 r.p.m., rotates about shaft  42 S. Material fragmented by the impacting teeth  41  is then radially propelled along the curvature of the screen  43 . Screen  43 , in cooperation with the impacting teeth  41 , serves to further fragment by grating the waste materials W upon the surface and screen of  43  refine the waste W into a desired particle screening size until ultimately fragmented to a sufficient particle size so as to screen through screen  43  for collection and discharge by discharging conveyor  51 . A discharging motor M D  serves as a power source for powering a discharging means  300  that conveys processed products D from the machine  10 . 
     Tremendous forces are thus generated within the fragmenting or grinding chamber  100  as the shearing or breaker teeth  41  impact with high rotational velocity against the waste W. If waste W is unacceptably dense, as the teeth  41  impact the waste W, damage may be done to the machine  10 . Such damage may include, inter alia, breakage of teeth  41 , damage to fragmenting rotor shaft, fragmenting rotor bearing and the like. It would be highly desirable to have a method for identifying waste W that is essentially ungrindable or too dense to grind without damage to the machine  10 . 
       FIGS. 3   a  and  3   b  provide basic block diagrams of one embodiment of the apparatus used to practice the inventive method. The fragmentation machine is represented generally by line  10  in  FIG. 3   a.  The fragmenting or grinding chamber  4  is illustrated, with the power shaft  42 S shown in rotating communication with power shaft bearing  42 B. Power shaft bearing  42 B is shown as generally enclosed within power shaft bearing housing  42 H. The vibration detection assembly  100  is shown as communicating in this embodiment with the bearing housing  42 H, located adjacent the fragmenting chamber  4 , though other mounting locations for the assembly  100  may readily present themselves to those skilled in the art. The assembly  100  may be in wired or wireless communication with an operator interface system  200 . 
     The operator interface system  200  may comprise a display screen and data entry means, e.g., a keyboard or the equivalent, well known data display and entry mechanisms not shown in the figures. The operator interface system  200  may thus allow the operator to send and/or receive data from the vibration detection assembly  100  using wired or wireless communication mechanisms well known to those skilled in the art. The operator interface system  200  may also communicate with various components and/or systems within machine  10  via communication means  300 . 
     The operator interface system  200  may further comprise at least one warning annunciator that may be actuated when potentially ungrindable material is detected by the inventive method. The warning annunciator(s) may be either audio or visual warning mechanisms. For example, warning lights may be incorporated into the operator interface system  200 . The operator interface system  200  may further display a fault and/or warning message on the display. Finally, the operator interface system may incorporate or actuate a warning siren in response to the detection of potentially ungrindable waste material in the fragmenting chamber. 
     Communication means  300  may comprise at least one data transfer line in addition to a variety of alternative communication mechanisms and methods including, e.g., wireless communication means. Communication means  300  comprises, inter alia, the means by which the vibration detection assembly  100  may respond to a detected vibration level that is above a pre-set alert of interventional upper limit. By way of example, communication means  300  may communicate with the motors M P , M R , M D , and/or M F  to shut down or disengage one or more of the motors in response to a vibration level that exceeds pre-set levels, thus indicating the presence of potentially ungrindable material within the fragmenting chamber. In the embodiment shown in  FIG. 3   a,  the operator may also utilize communication means  300  to send data and/or commands to various machine components and/or systems. 
     Alternatively, the vibration detection assembly  100  may respond via direct communication with certain machine components and/or systems in various embodiments that may not include an operator interface system  200 . Such alternative communication may occur using wired and/or wireless communication means. 
       FIG. 3   b  illustrates a preferred embodiment of the vibration detection assembly  100  in greater detail. The assembly  100  may comprise a vibration detector  110  shown attached to the power shaft bearing housing  42 H, a transceiver  120  for receiving the vibration signals from the detector  110 , converting the signals into a digital signal and transmitting the digital signals to a processor or controller, e.g., a programmable logic controller  130  that is capable of reading and evaluating the digital vibration signals. The vibration detector  110  may preferably be an accelerometer, a device well known in the art to detect vibration levels. Other vibration detection mechanisms exist in the art and may be readily adaptable to the present invention. 
     The vibration detector  110  may be placed in a variety of locations on, or in, the waste fragmentation machine. A preferred location for the vibration detector  110  is adjacent the fragmenting chamber  4 , e.g., attached to the bearing housing  42 H. It is understood that the vibration assembly  100  may be designed to be a kit, retrofitted to existing waste fragmenting machines. Alternatively, the vibration assembly  100  may be integrated into the manufacture of a waste fragmentation machine. Further, the operator interface system  200  may be retrofitted to a machine and/or the assembly  100 , or manufactured as integrated with the machine and/or assembly  100 . 
     The apparatus relating to the inventive method having been described in certain embodiments, various embodiments of an operational method thereof will now be discussed. It will be understood that the order of the steps described herein may be arranged in a variety of ways and still achieve the inventive objects. Thus, the invention is not limited to the exemplary ordering described herein. 
     With specific reference now to  FIG. 4 , and as discussed above, the vibration analyzer apparatus, e.g., vibration assembly, operator interface system and supporting communication means, may be installed in several ways. The apparatus may either retrofitted to an existing waste fragmentation machine or manufactured as an integrated component to such machine  10 . At least one upper vibration limit may be programmed, and stored within, a programmed logic controller, or equivalent.  200 . For example, a first upper vibration limit may comprise at least one alert upper limit that may be set at a moderate vibration level, but a level that may be of concern if the machine continues to operate at the alert upper limit for a period of time. Such an alert upper limit may be programmed to not provide annunciation until the alert upper limit is met or exceeded for a given period of time, e.g., detection of vibration levels at or above the alert upper limit vibration level and that persist for at least 30 seconds. The operator alert may be achieved by aural or visual annunciation mechanisms. For example, a warning light may be actuated and/or a warning siren or the like. 
     In addition, at least one interventional upper limit may be programmed and stored within the programmed logic controller for vibration levels that represent a danger to the machine. This interventional upper limit, when exceeded even once by the monitored vibration levels, may indicate automatic intervention, e.g., one or more of the following intervention steps: stopping the powered feed system; reversing the powered feed system; stopping the fragmenting rotor; reversing the fragmenting rotor; locking out the power feed system and/or fragmenting rotor; requiring operator action before resuming fragmenting. The locked-out power feed system and/or fragmenting rotor may require the operator to enter a password before normal fragmenting may resume. This ensures to the extent possible that the potentially ungrindable material has been eliminated from the fragmenting chamber before resuming operation. Alternatively, the interventional upper limit program may require vibration levels at or above the upper limit for a length of time, e.g., at least 10 seconds, before intervening. 
     Prior to beginning the fragmenting process for a given work period, e.g., workday or work shift, a daily baseline vibration level signal for the waste fragmenting machine may be established  300 . This may be accomplished by monitoring the vibration signals emitted by the machine without any material in the fragmenting chamber. 
     One or more of the programmed upper limits described above in step  200  may be fixed prior to, or concurrent with the installation of the vibration detection assembly on the waste fragmenting machine and remain the same throughout the life of the assembly and/or machine. Alternatively, one or more of the upper limits may be programmed to vary from work period to work period based upon the established baseline signal, using the baseline signal essentially as a calibration mechanism. This calibration mechanism may account for vibrational differences due to environmental factors such as temperature fluctuations (ambient temperature as well as internal machine temperature), humidity, external acoustic noise, electromagnetic interference and the like. Accordingly, an increase or decrease in a work period baseline signal may result in a calibrated increase or decrease in the alert upper limit and/or interventional upper limit for the remainder of the work period, or until the baseline is re-established. 
     When the programming of the controller or equivalent is complete  200  and the daily baseline established, the vibration analyzer may be used to monitor for potentially ungrindable material within the fragmenting chamber  400 . This is initiated by actuation of the power feed system that moves waste material into the fragmenting chamber. Inside the fragmenting chamber, the fragmenting rotor, with shearing or breaking teeth, is rotating at a high rate of speed, e.g., in the range of 1800-2500 r.p.m. 
     If material is fed into the fragmenting chamber that is too hard or dense to grind without damage, the shearing or breaking teeth will strike this material creating vibration levels that may exceed one or more of the vibration level upper limits programmed in step  200 . The vibration analyzer monitors the machine vibrations, compares them with the programmed upper limit(s) and determines whether the monitored vibrations exceed one of the upper limit(s)  500 . Specifically, the vibration detector, preferably an accelerometer, detects the vibrations and the controller compares the signals with the established limits previously programmed and stored within the controller. If one of the upper limit(s) is exceeded, then the vibration analyzer will actuate an operator alert, comprising aural and/or visual alerts, that indicate to the operator the presence of potentially ungrindable material within the fragmenting chamber of the waste fragmentation machine  600 . 
     If, for example, the interventional upper limit discussed above is exceeded, the vibration analyzer may be programmed to intervene with at least one of the machine&#39;s components and/or systems  700 . One such interventional step may be stopping the power feed system  710 . Such a step may be accomplished by disengaging the motor M P  driving the powered feed rotor and/or the motor M F  driving the infeed conveyer as discussed above in connection with  FIGS. 1 and 2 . A second intervention may comprise reversing the power feed system by, e.g., reversing the motor M P  and/or the motor M F  to reverse the powered feed rotor and/or infeed conveyer, respectively  720 . Another interventional step may comprise locking out the system to prevent further operation until affirmative action is taken by an operator  730 . Such intervention may interrupt power to one or more of the motors M P , M R  and/or M F . Subsequently, the operator may resume the system only after eliminating the ungrindable material, if any,  740  and unlocking the system by, e.g., entering the correct password into the operator interface system  750 . 
     The above specification describes certain preferred embodiments of this invention. This specification is in no way intended to limit the scope of the claims. Other modifications, alterations, or substitutions may now suggest themselves to those skilled in the art, all of which are within the spirit and scope of the present invention. It is therefore intended that the present invention be limited only by the scope of the attached claims below: