Patent Grant
7325759
This invention relates generally to a method for monitoring and analyzing the processes occurring during operation of a waste fragmentation machine to minimize damage.
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'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.
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.
a is a breakaway of one embodiment of the apparatus used in the inventive method.
b is a block diagram of one embodiment of the apparatus used in the inventive method.
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.
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 MF in cooperative association with a power feed rotor drum 8D powered by power feed motor MP.
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 9D and an idler pulley 9E 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 9G. Feed motor MF in cooperative association with gear box 9G, apron drive pulley 9P, chain 9F, and apron drive sprocket 9D driven about feed shaft 9S serves to drive continuous infeed conveyer 9 about feed drive pulley 9D and idler pulley 9E.
A power feed system 8 driven by motor MP and in cooperative association with the infeed conveyer 9, driven by motor MF, 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 8D equipped with projecting feeding teeth 8A positioned for counterclockwise rotational movement about rotor drum 8D. Drum 8D may be driven by power feed shaft 8S which in turn is driven by chain 8B, drive sprocket 8P and motor MP.
A rotary motor MR 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 42S, which is in turn powered by a suitable power source such as motor MR. Motor MR is drivingly connected to power shaft pulley 42P which drivingly rotates power shaft 42S within power shaft bearing 42B. 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 42S. 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 MD 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.
a and 3b 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
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 MP, MR, MD, and/or MF 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
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.
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 42H, 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 42H. 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
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'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 MP driving the powered feed rotor and/or the motor MF driving the infeed conveyer as discussed above in connection with
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:
| Number | Name | Date | Kind |
|---|---|---|---|
| 4560110 | Burda | Dec 1985 | A |
| 6714880 | Carle et al. | Mar 2004 | B2 |
| 20030178515 | Boerhout et al. | Sep 2003 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20060266855 A1 | Nov 2006 | US |
