Patent Publication Number: US-2013234494-A1

Title: Sensors on a Degradation Platform

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to degradation operations and especially sensors for degradation operations. Degradation operations may include mining, trenching, and road milling. It is known to use sensors in degradation operations to detect certain conditions of a surface, e.g. man-hole covers for road milling operations. For example, U.S. Pat. No. 7,077,601 to Lloyd, which is herein incorporated by reference for all that it contains, discloses a series of metal detectors to detect iron utility structures in an asphalt surface. 
     It is also known in the art to use sensors to detect forces acting on a milling drum. For example, U.S. Pat. Pub. No. 2011/0193397 to Menzenbach et al., which is herein incorporated by reference for all that it contains, discloses a construction machine wherein a parameter is sensed corresponding to a reaction force acting on a milling drum. 
     Sensors may also be used to detect wear conditions on a milling roller. For example, U.S. Pat. No. 7,905,682 to Holl et al., which is herein incorporated by reference for all that it contains, discloses a machine chassis supported by a running gear, wherein a drive motor is assigned to the running gear, and a signal pickup unit detects the power consumption of the drive motor which relates to changed wear conditions of the milling roller. Holl et al. also discloses a machine chassis that can be height-adjusted by an adjustment device wherein forces occurring during milling may be indirectly detected by detecting fluid pressure in the adjustment device. 
     Despite the advancements as shown in the prior art, it is believed that there is still a need to develop better means to determine and/or detect worn, damaged or malfunctioning picks. 
     BRIEF SUMMARY OF THE INVENTION 
     A degradation assembly may comprise a platform with a surface, a plurality of picks each with a hard tip opposite a shank mounted on the surface, and a plurality of sensors disposed within the platform such that they can measure impacts on the picks. Each of the plurality of sensors may correspond with one of the plurality of picks. 
     The plurality of sensors may be disposed in at least one circular array. The plurality of sensors may also be disposed substantially parallel to the plurality of picks. The sensors may be disposed in a cavity on an external surface of the platform or on an internal surface. The sensors may also be disposed inward of either surface or inward of one of the picks. 
     The sensors may be strain gauges, accelerometers, or acoustic sensors. If the sensors are strain gauges they may be uniaxial strain gauges or triaxial rosettes. 
     The platform may be a drum, a chain, a blade, or a drill bit. If the platform is a drum the sensors may be disposed around a perimeter of the drum. 
     Each of the plurality of sensors may comprise a unique identifier signal and be in communication with a processor. The processor may be in communication with a visual interface. The processor may be disposed within the platform and store data received from the plurality of sensors. The sensors may also comprise a wireless communication device for communication with the processor. 
     A selected pick may be detected and its location determined by measuring impacts on a plurality of picks with a plurality of sensors, detecting a variation on at least one of the picks with the at least one of the sensors and then determining a location of the selected pick with more than one of the sensors. This may be accomplished by detecting the variation by measuring a first reading by one sensor and determining the location by measuring dissimilar readings by adjacent sensors. This may also be accomplished by measuring three readings by three sensors, calculating three distances from each of the three sensors based on magnitudes of the three readings and finding the union of the three distances. This may alternatively be accomplished by forming at least two triangles and determining the location of the selected pick by the union of the at least two triangles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially cut-away view of an embodiment of a degradation platform on a road milling machine. 
         FIG. 2  is a cross-sectional view of an embodiment of a degradation platform. 
         FIG. 3   a  is a cross-sectional view of an embodiment of a pick and a sensor in compression. 
         FIG. 3   b  is a cross-sectional view of an embodiment of a pick and a sensor in tension. 
         FIG. 4  is an orthogonal view of an embodiment of a degradation platform with sensors disposed in circular arrays. 
         FIG. 5  is a perspective view of an embodiment of a processor displaying a signal comprising a process of trilateration. 
         FIG. 6  is a perspective view of another embodiment of a processor displaying a signal comprising two triangles. 
         FIG. 7  is a cross-sectional view of an embodiment of a degradation platform with a plurality of cavities housing sensors. 
         FIG. 8  is a cross-sectional view of an embodiment of a degradation platform with a cavity housing a processor. 
         FIG. 9  is an orthogonal view of an embodiment of a degradation platform with sensors disposed in a configuration parallel to a configuration of the plurality of picks. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT 
     Referring now to the figures,  FIG. 1  discloses an embodiment of a road milling machine  101 . The road milling machine  101  also known as a cold planer, may be used to degrade a natural or man-made formation  102  such as pavement, concrete or asphalt prior to placement of a new layer. The arrow  103  shows the machine&#39;s direction of travel. 
     The road milling machine  101  may comprise a degradation platform; in the present embodiment the degradation platform is a degradation drum  104 . The degradation drum  104  may comprise a plurality of blocks  105  secured to its outer surface. A plurality of picks  106  may be secured to the degradation drum  104  within the plurality of blocks  105 . During normal operation, the degradation drum  104  may be configured to rotate causing the picks  106  to engage and degrade the formation  102 . In other embodiments of the present invention, the degradation platform may be a chain, blade, drill bit, or other moving part of a mining, trenching or road milling machine that may cause picks to engage and degrade formations of various types. 
       FIG. 2  discloses a cross-sectional view of a degradation drum  204  comprising a plurality of picks  206  mounted on an outside surface  208  and configured to degrade a formation. The degradation drum  204  may be hollow to minimize its overall weight. The degradation drum  204  may also be filled with water, antifreeze, or the like. 
     A plurality of sensors  210  may be disposed around a perimeter of the degradation drum  204  and inward of the outside surface  208 . Each sensor of the plurality of sensors  210  may be disposed such that it can measure impacts on at least one of the plurality of picks  206 . The picks  206  may each comprise a hard tip  220  configured to encounter high impacts as it breaks up hard surface formations. On occasion, one of the plurality of picks  206  may become damaged and/or dislocated from its position on the degradation drum  204 . Damage to at least one of the picks  206  may cause abnormal stress and wear to other components of the degradation drum  204  leading to a shorter lifetime for all parts. A damaged pick may also be difficult to identify among the plurality of picks  206  disposed on the degradation drum  204 . It is an object of the current invention for the plurality of sensors  210  to be configured to detect a damaged pick and determine the damaged pick&#39;s location on the degradation drum  204 . 
     The plurality of sensors  210  may be selected from a group consisting of strain gauges, accelerometers, acoustic sensors, and combinations thereof. In the case of the sensors being strain gauges, they may be selected from a group consisting of uniaxial strain gauges, triaxial rosettes, and combinations thereof In the current embodiment, the plurality of sensors  210  are uniaxial strain gauges  211  configured to measure the strain on the picks  206  as forces from a formation are applied to the plurality of picks  206 . The uniaxial strain gauges  211  may comprise a thread form which may allow the uniaxial strain gauges  211  to be rotated into a cavity on the outside surface  208 . 
     The plurality of sensors  210  may be connected by a wire  212  disposed within the degradation drum  204 . The wire  212  in the embodiment shown is a single armored coaxial wire. The wire  212  may connect the plurality of sensors  210  with a processor (not shown). In the present embodiment, the wire  212  connects the plurality of sensors  210  in a bus network and runs to the processor through an arm  217  rigidly attached to the drum  204 . The sensors  210  may be configured to communicate with the processor through the wire  212  by a unique identifier signal  213 . The sensors  210  may each comprise a unique identifier which may set the sensor apart from the rest of the sensors in the plurality. From the unique identifier signal  213  the processor may recognize from which sensor the signal is sent. In the embodiment shown, a sensor  214  comprises a unique identifier  215 . The sensor  214  may communicate with the processor by sending the unique identifier signal  213  that corresponds to the unique identifier  215 . 
       FIGS. 3   a  and  3   b  each disclose cross-sectional views of a pick and a sensor being acted on by a force, represented by an arrow  322   a  and  322   b  respectively.  FIG. 3   a  discloses a sensor  314   a  disposed underneath a back side  321  of a pick  306   a.  As a force, represented by arrow  320   a,  acts on the pick  306   a,  the pick&#39;s back side  321  is forced into a degradation drum  304   a  as represented by the arrow  322   a.  As the pick&#39;s back side  321  is forced into the degradation drum  304   a,  the sensor  314   a  is in compression. The amount of force acting on the pick  306   a  may be proportional to the amount of compression detected by the sensor  314   a  which may allow the sensor  314   a  to determine how much force is acting on the pick  306   a.    
       FIG. 3   b  discloses a sensor  314   b  disposed underneath the front side  323  of a pick  306   b.  As a force, represented by arrow  320   b,  acts on pick  306   b,  the pick&#39;s front side  323  is forced away from a degradation drum  304   b  as represented by the arrow  322   b.  As the pick&#39;s front side  323  is forced away from the degradation drum  304   b,  the sensor  314   b  is in tension. The amount of force acting on the pick  306   b  may be proportional to the amount of tension detected by the sensor  314   b  which may allow the sensor  314   b  to determine how much force is acting on the pick  306   b.    
       FIG. 4  discloses a degradation platform comprising a degradation drum  404  with a plurality of picks  406  mounted on an outer surface of the degradation drum  404 . (A portion of the plurality of picks  406  has been removed for clarity) A plurality of sensors  410  may be disposed within the degradation drum  404  and be configured in at least one circular array around a perimeter of the degradation drum  404 . Multiple circular arrays may allow the plurality of sensors  410  to be disposed in a matrix defined by columns and rows which may allow the location of an individual sensor  412 ,  413 , or  414  to be easily established. By knowing the location of a sensor  412 ,  413 , or  414 , the location of a selected pick may be more accurately determined. 
     During regular operation, the plurality of sensors  410  may determine a baseline level detection reading  430 . The baseline detection reading  430  may be considered normal for correctly-working unworn picks. There may be instances during operation that the plurality of sensors  410  provide detection readings other than the baseline detection reading  430 , for example if a pick becomes worn, damaged or dislocated. 
     In the present embodiment, a selected pick  431  is damaged. A sensor  412  is disposed adjacent to the selected pick  431  and may provide a detection reading  432 . The detection reading  432  may indicate a low stress detection reading due to substantially less force acting on the selected pick  431 . Sensors  413  and  414  are disposed adjacent to picks in the vicinity of the selected pick  431  and may provide detection readings  433  and  434  respectively. The detection readings  433  and  434  may exhibit high stress detection readings due to an increased amount of forces acting on the nearby picks that attempt to compensate for the selected pick  431 . The low and high detection readings as indicated in the detection readings  432 ,  433  and  434  may be sent to a processor (not shown) where the information may be used to detect the selected pick  431  and determine its location on the degradation drum  404 . 
       FIG. 5  discloses an embodiment of a processor  540 . As shown in the current embodiment, the processor  540  may be housed in a computer or other device that receives data and which may comprise a visual interface  549  configured to display at least one signal  541  for an operator in real time. The processor  540  may be disposed on or off site, and as shown, it may be disposed within the milling machine or other vehicle. 
     A method for detecting and determining a location of a selected pick may comprise measuring a first reading by an adjacent sensor and measuring dissimilar readings by sensors in the vicinity. For example, the signal  541  which may be displayed on the visual interface  549  may show a low detection reading  532  and high detection readings  533  and  534 . 
     Another method for detecting and determining a location of a selected pick may comprise measuring three readings by three sensors, calculating three distances from each of the three sensors based on magnitudes of the three readings and finding the union of the three distances. For example, a first circle  542  comprising a first radius  552  may correspond to a low detection reading  532 . The length of the first radius  552  may be correlated with the magnitude of the first detection reading  532 . A second circle  543  comprising a second radius  553  and a third circle  544  comprising a third radius  554  may correspond to second and third detection readings  533  and  534  respectively, and the lengths of the second and third radii  553  and  554  may be correlated with the magnitude of the second and third detection readings  533  and  534 . The first, second, and third circles  542 ,  543 , and  544 , may intersect at an intersection point  560 . The intersection point  560  may correspond to the location of the damaged pick on the milling drum. In some embodiments, the at least three circles may not intersect at an exact point but may form in area which is inside each of the at least three circles. The area, called a union, may correspond to an area on the milling drum in which the damaged pick is located. 
       FIG. 6  discloses another embodiment of a processor  640  housed in a computer comprising a visual interface  649  configured to display a signal  641  from a plurality of sensors disposed within a degradation platform. A method for detecting and determining a location of a selected pick may comprise forming at least two triangles and determining the location of the selected pick by the union of the at least two triangles. For example, the signal  641  may display first detection readings from sensors disposed adjacent to a selected pick  631  which may be a damaged pick. In the embodiment shown, the first detection readings are low detection readings  650   a  and  650   b.  The signal  641  may also display second detection readings from sensors disposed in the vicinity of the selected pick  631 . In the embodiment shown, the second detection readings are high detection readings  651   a,    651   b,    651   c,  and  651   d.  The high detection readings  651   a  and  651   b  and the low stress detection reading  650   b  may form a first triangle  652 . The high detection readings  651   c  and  651   d  and the low detection reading  650   a  may form a second triangle  653 . Other triangles may be formed from additional detection readings. The location of the selected pick  631  may be determined by the intersection of the at least two triangles  652  and  653 . 
       FIG. 7  discloses a cross-sectional view of another embodiment of a milling drum  701  comprising a plurality of picks  706  mounted on an outside surface  708 . A second internal surface  718  of the milling drum  701  may comprise at least one cavity  760 . 
     The cavity  760  may be configured to house at least one sensor  714 . The sensor  714  in the current embodiment is a uniaxial strain gauge that may be bonded to the second internal surface  718 . The sensor  714  may be connected to a transmitter  761  that is configured to communicate with a processor (not shown) via a wireless communication. 
     Due to the sensor  714  being disposed within the cavity  760 , a coating  762  may overlay the second internal surface  718 . The coating  762  may comprise an epoxy or other type of resin that is configured to protect the sensor  714  and transmitter  761 . 
     The cavity  760  may also provide compliancy for the sensor  714 . The compliancy may be advantageous in allowing the sensor  714  to more easily detect the forces acting on the picks  706 . 
       FIG. 8  discloses a cross-sectional view of another embodiment of a milling drum  801  comprising a cavity  860  disposed on an internal surface  863 . The cavity  860  may house a processor  840 . A plurality of sensors  810  disposed within the internal surface  863  of the milling drum  801  may each connect with the processor  840  individually with a wire, and a coating  862  may overlay the internal surface  863  to protect the processor  840  and wires. In the embodiment shown, the sensors  810  are triaxial rosette strain gauges. These strain gauges may be configured to measure forces acting on a plurality of picks  806  in three different directions, along x, y, and z axes. During normal drilling operation, the processor  840  may be configured to store data received from the plurality of sensors  810 . Data from the sensors  810  may be extracted from the processor  840  when not in operation. 
       FIG. 9  discloses an orthogonal view of an embodiment of a milling drum  901  comprising a plurality of picks  906  and a plurality of sensors  910 . The picks  906  may be configured to maximize the effectiveness of degrading a formation and the sensors  910  may be disposed in a configuration substantially parallel to the configuration of the picks  906 . It is believed that disposing the sensors  910  in parallel configuration to the picks  906  may allow the sensors  910  to better determine the location of a selected pick. 
     Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.