Abstract:
A machine tooth for heavy equipment can be monitored by coupling an RFID tag to the heavy machine tooth and positioning an RFID reader to read the RFID tag. The RFID reader provides an indication that the heavy machine tooth is separated from the heavy machine. The heavy machine tooth is configured, for example, to be mounted on a bucket of a heavy machine.

Description:
BACKGROUND 
       [0001]    The invention relates to detection and locating of heavy machine teeth, specifically the use of radio frequency identification (RFID) tags to determine when a metal tooth is no longer on a bucket of a heavy machine. 
         [0002]    Heavy machines (e.g., mining equipment such as draglines and shovels) utilize steel teeth in their bucket designs. The teeth are used for several reasons: They provide a smaller point of surface area when digging into the earth, helping to break up the earth, and requiring less force than the larger surface area of a bucket itself. In addition, the teeth provide easily replaceable wear points that save the bucket itself from wearing down. However, as a tooth wears down, there is currently no method to measure wear without physically removing the tooth. 
         [0003]    When the teeth wear down, they typically fall off The current method of detecting when a tooth falls off is an expensive machine vision system that looks at the bucket and detects when a tooth has gone missing. This system is extremely costly to implement, and only lets the operator know that the tooth has gone missing, not where it is. Once a crew notices a tooth is missing, they haul away an average ten truckloads of material in hopes of locating and separating out the fallen tooth. If they are unable to locate the tooth, the tooth can end up in a crusher. In addition the tooth can become stuck in the crusher and be ejected from the crusher, potentially harming other equipment. 
       SUMMARY 
       [0004]    In one embodiment, the invention provides a method of monitoring a heavy machine tooth. The method includes coupling an RFID tag to the heavy machine tooth and positioning an RFID reader to read the RFID tag. The RFID reader provides an indication that the heavy machine tooth is separated from the heavy machine. 
         [0005]    In other embodiments, the invention provides a heavy machine tooth monitoring system that includes a heavy machine tooth configured to be mounted on a bucket of a heavy machine, an active RFID tag coupled to the tooth, and an RFID reader configured to read data from the RFID tag. 
         [0006]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a side view of an exemplary shovel. 
           [0008]      FIGS. 2A and 2B  illustrate the operation of an exemplary mining site. 
           [0009]      FIG. 3  is an exploded view of a construction of a bucket tooth incorporating an RFID tag. 
           [0010]      FIG. 4  is another view of the bucket tooth of  FIG. 3 . 
           [0011]      FIG. 5  is a cut-away view of the bucket tooth of  FIG. 3 . 
           [0012]      FIG. 6  is a plan view of another construction of a bucket tooth incorporating an RFID tag. 
           [0013]      FIG. 7  is a plurality of views of a third construction of a bucket tooth incorporating an RFID tag. 
           [0014]      FIG. 8  is a plan view of a construction of a ceramic plug for inserting an RFID tag into the bucket tooth of  FIG. 7 . 
           [0015]      FIG. 9  is a schematic diagram of a wear detection circuit. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
         [0017]    Heavy machines are used to move large amounts of earth in industries such as mining and construction. Some heavy machines (e.g., an electric shovel) include buckets for scooping up the earth. The buckets often include a plurality of teeth to help break up the earth, and make it easier to scoop the earth into the bucket. 
         [0018]      FIG. 1  shows an exemplary electric shovel  100  used for surface mining applications. The electric shovel  100  includes a mobile base  105  supported on drive tracks  110 . The mobile base  105  supports a turntable  115 , and a machinery deck  120 . The turntable  115  permits full 360° rotation of the machinery deck  120  relative to the base  105 . 
         [0019]    A boom  125  is pivotally connected at  130  to the machinery deck  120 . The boom  125  is held in an upwardly and outwardly extending relation to the deck by a brace or gantry in the form of tension cables  135  which are anchored to a back stay  140  of a stay structure  145  rigidly mounted on the machinery deck  120 . 
         [0020]    A dipper or bucket  150  includes a plurality of teeth  152 , and is suspended by a flexible hoist rope or cable  155  from a pulley or sheave  160 , the hoist rope is anchored to a winch drum  165  mounted on the machinery deck  120 . As the winch drum rotates, the hoist rope  155  is either paid out or pulled in, lowering or raising the dipper  150 . The boom pulley  160  directs the tension in the hoist rope  155  to pull straight upward on the shovel dipper  150 , thereby producing efficient dig force with which to excavate the bank of material. The dipper  150  an arm or handle  170  rigidly attached thereto, with the dipper arm  170  slideably supported in a saddle block  175 , which is pivotally mounted on the boom  125  at  180 . The dipper arm  170  has a rack tooth formation thereon (not shown) which engages a drive pinion or shipper shaft (not shown) mounted in the saddle block  175 . The drive pinion is driven by an electric motor and transmission unit  185  to effect extension or retraction of the dipper arm  170  relative to the saddle block  175 . 
         [0021]    The shovel boom  125  is a major structural component in size, shape, and weight. Its main purpose is to hold the boom pulley  160  in an advantageous position for efficient hoist dipper pull through the bank. Another major purpose of the boom  125  is to mount the shipper shaft at a sufficient height and outward radius from the centerline of rotation of the shovel  100 . The shipper shaft powers the shovel handle to extend and retract the dipper  150 . These two features of an electric shovel digging attachment make the shovel uniquely qualified to reach and dig high bank formations safely away from the shovel. The shovel in this regard is also able to reach a great volume of material in one sitting without propelling closer to the bank. 
         [0022]    The bucket teeth  152  are removably attached to the bucket  150 . This enables broken or worn teeth  152  to be easily replaced. However, this leads to teeth  152  occasionally breaking or falling off of the bucket  150 . In some circumstances, a tooth  152  will break/fall off the bucket  150  and end up in the earth being mined (i.e., in the bucket  150 ). When the earth in the bucket  150  is deposited in a truck, the tooth  152  goes into the truck as well. Often the earth in the truck is taken to a crusher to be crushed. When the truck empties its contents into the crusher, the tooth  152  goes into the crusher as well, potentially damaging the crusher, being expelled from the crusher and damaging other equipment, or being damaged in the crusher. 
         [0023]      FIGS. 2A and 2B  represent a typical mining operation. The shovel  100  digs up earth  200  with its bucket  150 , and dumps the earth  200  into a truck  205 . Once the truck  205  is full, the truck  205  takes the earth  200  to another location (e.g., at the mining site or remote from the mining site). In some operations, the truck  205  takes the earth  200  to a crusher  210 . The truck  205  deposits the earth  200  onto a conveyor  215  which feeds the earth  200  into the crusher  210  which crushes the earth  200  into smaller components  220 . 
         [0024]    The invention uses an active RFID tag embedded in or attached to the metal tooth  152  of the heavy machine bucket to enable detection of a tooth  152  missing from the bucket  150 . 
         [0025]    The invention uses an RFID reader  225  located on a structure (e.g., an exit gate) through which the truck  205  passes after being filled. The RFID reader  225  checks if an RFID tag passed near the structure. If an RFID tag is detected, an alarm can be triggered enabling the truck  205  to be searched to determine if the detected RFID tag and corresponding tooth  152  was in the bed of the truck  205 . If a tooth  152  containing an RFID tag had broken/fallen off the bucket  150  and was in the truck  205 , it could be found before leaving the site or being deposited in the crusher  210 . Preferably, the RFID reader  225  is positioned a far enough distance away from the bucket  150  that the reader  225  does not detect RFID tags in the teeth  152  that are still in place on the bucket  150 . 
         [0026]    In addition, an RFID reader  230  can be positioned before the entrance to the crusher  210  to detect the RFID tag on a tooth  152  prior to the tooth  152  entering the crusher  210  (e.g., the reader  230  could be positioned over the conveyor  215  feeding the crusher  210 ). Again, if the reader  230  detects an RFID tag, an alarm is triggered and the conveyor  215  and/or crusher  210  is/are stopped, enabling the tooth  152  to be located prior to entering the crusher  210 . 
         [0027]    An RFID tag in a tooth  152  can include information identifying the tooth  152 . For example, the RFID tag can be written with data such as, but not limited to, a serial number, an origin, a date of manufacture, etc. This stored information can enable a user to quickly determine where the tooth  152  came from promoting faster repair of the bucket  150  or returning of the tooth  152 . 
         [0028]    In some embodiments, an RFID reader  235  is included in the heavy machine  100  itself (see  FIG. 1 ). The reader  235  reads all of the RFID tags located on the machine  100 , including the tags on the teeth  152 . A controller or computer receives information from the reader  235  about the tags detected. The controller then provides diagnostic information to a user. This information can include when the tooth  152  was installed, how many hours the tooth  152  has been in operation, etc. In addition, should a tooth  152  break/fall off, the controller alerts the user of this condition enabling the lost tooth  152  to be found quickly and replaced. 
         [0029]    In some embodiments, additional circuitry is included with the RFID tag to determine the amount of wear of a tooth, enabling preventative maintenance to be performed before a tooth fails. 
         [0030]    In some embodiments, the RFID tag  300  is detuned when the tooth  152  is mounted to the bucket  150 . When the tooth  152  breaks/falls off the bucket  150 , the signal strength of the RFID tag  300  increases. The reader  235  detects the increase in signal strength and determines that the tooth  152  has broken/fallen off the bucket  150 . 
         [0031]      FIGS. 3-5  show a view of a heavy machine bucket tooth  152 . The tooth  152  includes an active RFID tag  300  encased in a ceramic enclosure  305 , the ceramic enclosure  305  is then encased in steel  310 . A separate control circuitry can also be included in the ceramic enclosure  305  to activate the RFID tag  300  when the tooth  152  is shipped or installed, saving battery power and extending the life of the RFID tag  300 . The ceramic enclosure  305  with the RFID tag  300 , and any other circuitry, is placed in a mold into which liquid steel is poured to form the tooth  152 . The ceramic enclosure  305  protects the RFID tag  300  from the heat of the liquid steel. The RFID tag  300  is detuned such that the steel of the tooth  152  tunes the RFID tag  300  to the correct frequency, using the tooth  152  as an antenna. In some embodiments, a tuning circuit in the RFID tag  300  tunes the tag  300  once the tag  300  is activated in the tooth  152 . 
         [0032]      FIG. 6  shows another construction of a heavy machine bucket tooth  152  incorporating an RFID tag  300 . The tag  300  is mounted to an end  600  of the tooth  152 . The end  600  is inserted into a mounting bracket  605  and the tooth  152  is secured to the mounting bracket  605 . In this construction, the RFID tag  300  takes advantage of the metal of the tooth  152  and the bracket  605 , using backscattering to increase an intensity of the RFID signal. 
         [0033]      FIG. 7  shows a construction of a heavy machine bucket tooth  152  arranged to receive an RFID tag. The tooth  152  includes a hole  700  drilled into the base of the tooth  152 . A cylindrical RFID tag is inserted into the hole  700 . In some constructions, a ceramic disk is placed over the RFID tag, and the hole  700  is welded shut. 
         [0034]      FIG. 8  shows a construction of a ceramic plug  800  for insertion in the tooth  152  of  FIG. 7 . The ceramic plug  800  encapsulates an RFID tag and a tooth wear detection circuit. Four probes  805 ,  810 ,  815 ,  820  extend out of the ceramic plug  800 . When the ceramic plug  800  is inserted into the hole  700  of the tooth  152 , the probes  805 - 820  each contact the tooth  152  and are thereby electrically coupled to the tooth  152 . The wear detection circuit uses the probes  805 ,  810 ,  815 ,  820  to electrically test the tooth  152  and determine the wear of the tooth  152 . The wear detection circuit provides data to the RFID tag  300  regarding the wear of the tooth  152  (e.g., amount of loss, useful life remaining, etc.). The RFID tag  300  then communicates (e.g., via a wired or wireless connection) the wear information to an RFID reader (e.g., in a cab of a shovel, to a portable RFID reader, etc.). 
         [0035]      FIG. 9  shows a wear detection circuit  900  used to determine wear of the tooth  152 . The circuit  900  uses a four-point resistance method to determine wear. A current source  905  produces a current that is applied to two of the probes  805  and  820 . The current flowing through the probes  805  and  820  is detected by a current transducer  910 . A voltage transducer  915  of the circuit  900  detects a voltage across the other two probes  810  and  815 . Using the detected current and voltage, a microcontroller  920  of the circuit  900  determines a resistance of the tooth  152 . The resistance varies based on the material composition of the tooth  152 , the permittivity of the tooth  152 , and the dimensions of the tooth  152 . As the tooth  152  wears, the resistance of the tooth  152  changes. The change in resistance can thus be used to determine the wear and tear on the tooth  152 . In some embodiments, the initial resistance (i.e., when the tooth  152  is new) is recorded in the RFID tag  300 . Also, in some embodiments, other resistance measurements (e.g., the resistance previously determined) are recorded in the RFID tag  300 . 
         [0036]    Various features and advantages of the invention are set forth in the following claims.