Patent Application
20130234494
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.
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.
a is a cross-sectional view of an embodiment of a pick and a sensor in compression.
b is a cross-sectional view of an embodiment of a pick and a sensor in tension.
Referring now to the figures,
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.
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'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.
a and 3b each disclose cross-sectional views of a pick and a sensor being acted on by a force, represented by an arrow 322a and 322b respectively.
b discloses a sensor 314b disposed underneath the front side 323 of a pick 306b. As a force, represented by arrow 320b, acts on pick 306b, the pick's front side 323 is forced away from a degradation drum 304b as represented by the arrow 322b. As the pick's front side 323 is forced away from the degradation drum 304b, the sensor 314b is in tension. The amount of force acting on the pick 306b may be proportional to the amount of tension detected by the sensor 314b which may allow the sensor 314b to determine how much force is acting on the pick 306b.
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.
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.
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.
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.
