INSPECTING GEAR TEETH IN AN OPEN GEAR SET

FIEUD OF THE INVENTION

[0001] The present disclosure is directed to an autonomous robotic system and method for non-destructive inspection of large open gear sets. More specifically, the present disclosure is directed to a system including a robot, an eddy current array (ECA) probe or a phased array ultrasonic testing (PAUT) probe or both and a computing system for inspecting gear teeth of girth gear sets.

BACKGROUND OF THE INVENTION

[0002] Non-destructive inspection of open gears identifies defects and wear of the open gears. For example, Canadian Patent Application Serial number 2956749 discloses a formfitting eddy current array probe for inspecting helical gears and a method of inspecting a girth gear set including a helical gear and a girth gear using the form-fitting eddy current array probe. This non-destructive inspection requires a human operator.

[0003] Inspecting gear teeth of large open gear sets is dangerous work and is very time consuming. It requires that the mill be stopped, the mill must then be locked out, and the gear guard must be removed before the human operator can access the gear teeth the mill. Depending on how many gear teeth can be accessed for the inspection, the mill must be rotated to be able to access more teeth. The mill must unlocked, rotated, then locked out for safe access to the gear teeth.

[0004] Eddy current technology is a widely used for quality control testing on objects such as wire, rods or tubes. This testing often involves having the test objects travel along a work path, passing through eddy current probe(s). The operators are competent as they routinely conduct tests. Presently available technology discloses that robots can be used in non-destructive testing using eddy current arrays. The technology requires an operator. Further, it is specific to structures with simple, non-complex geometry as the robot crawls on the surface of the structure being tested.

[0005] United States Patent Application Publication No. 20140210997 discloses a system for automated inspection of a surface; the system may include a self-propelled, steerable carriage capable of traversing the surface, the carriage having a camera positioned to view an object on the surface, and at least of one of a sensor capable of detecting a defect in the surface, a tool for treating the defect, and a sensor for inspecting a repair of the defect; and a computer controller connected to receive image data from the camera, communicate with and selectively actuate the at least of one of a sensor capable of detecting a defect in the surface, a tool for treating the defect, and a sensor for inspecting a repair of the defect, and control the carriage to move on the surface along one or more of a pre-set path and a path to one or more pre-set locations. Eddy current array technology is disclosed. This technology is specific to structures with simple, noncomplex geometry as the carriage crawls or otherwise moves on the surface of the structure being tested.

[0006] United States Patent Application Publication No. 20140067185 discloses methods and systems for inspecting a component within an assembled turbomachine. At least one miniature robotic device having a non-destructive testing structure attached thereto is configured to travel around a surface of the component. The non-destructive testing structure gathers data related to the surface and sends the data to a computing device connected to the at least one miniature robotic device. In one embodiment, the non-destructive testing structure comprises an image capture device and an infrared (IR) heat source. This technology is specific to surfaces with simple, non-complex geometry.

[0007] Eddy current testing can be performed on discs and other shaped objects constructed of conductive and/or non-magnetic materials to look for defects and wear. Eddy current testing may use eddy current coils designed to generate a changing magnetic field that may interact with the disc to generate an eddy current. Variations in the phase and magnitude of the generated eddy current may be measured by measuring changes to the current flowing in the coil. Alternatively, changes in phase and magnitude of the generated eddy current may be measured using a second coil. Changes in the phase and magnitude of the generated eddy current may indicate one or more flaws in the discs, such as small cracks that may lead to failures if not addressed. Due to their small size and rigidity, such probes make inspection of large discs and other large components that have varying and multiple geometries difficult and time-consuming, and therefore expensive.

[0008] Eddy current sensor arrays (ECA), as opposed to eddy current sensors, have been employed to measure stress on airplane parts, for example, on the landing gear, and to measure weights of components. For example, US Patent No. 8,237,433 discloses methods for monitoring of stresses and other material properties. These methods use measurements of effective electrical properties, such as magnetic permeability and electrical conductivity, to infer the state of the test material, such as the stress, temperature, or overload condition. The sensors, which can be single element sensors or sensor arrays, can be used to periodically inspect selected locations, mounted to the test material, or scanned over the test material to generate two- dimensional images of the material properties. Magnetic field or eddy current based inductive and giant magneto-resistive sensors may be used on magnetizable and/or conducting materials, while capacitive sensors can be used for dielectric materials. Methods are also described for the use of state- sensitive layers to determine the state of materials of interest. These methods allow the weight of articles, such as aircraft, to be determined. The operators are competent as they routinely conduct testing.

[0009] Eddy current arrays can also be used in production and inspection lines. For example, US Patent No. 8,264,221 discloses an eddy current probe assembly suitable for inspecting a test object with longitudinal shape, being passed through the assembly in the object's axial direction during an inspection session, the probe assembly comprising multiple probe modules being disposed in a radial plane and with the modules partially overlaying on each other forming an IRIS structure encircling an inspection zone, wherein a movement in unison of each of the probe modules closer to or further away from the center of the inspection zone makes the inspection zone enlarged or contracted. Spring tension is applied on each of the probe modules so that constant life-off in maintained between the probe modules and the test surface. Array of eddy current elements for each probe module and multiple layers of probe modules can be employed to achieve complete coverage of the test surface. The radial cross-sectional shapes of the test objects can be of round or polygonal. Again, testing is routine and therefore the operators are competent.

[0010] US Patent No. 5,315,234 discloses an eddy current device for inspecting a component includes an eddy current array circuit having respective pluralities of drive and sense elements and having an active face for positioning on a surface of the component during the inspection operation. A backing is disposed on a face of the eddy current array circuit opposite to the active face for concentrating an electromagnetic flux from the eddy current array circuit into the component when each of the plurality of drive elements is being energized. A mechanical arrangement is provided for supporting and deploying the backing and the array circuit to substantially conform with the surface portion under inspection and to cause each of the pluralities of drive and sense elements to be maintained at their respective substantially constant distances from the inspection surface during scanning, preferably at a controlled rate of scan. The distance is maintained using an inner backing or core, which is preferably a flexible, compressible material, such as a soft elastomeric material, an open or closed cell foam or the like, for applying a uniform pressure behind the array circuit and against the inspection surface to maintain the array elements at their substantially constant respective distances from the inspection surface. Regardless of whether there is an inner backing or a core, the shape of the probe is invariant as a rigid material is molded or shaped to conform to the desired shape of the surface of the component to be inspected.

[0011] A flexible eddy current probe, as opposed to an eddy current array (ECA) probe, is disclosed in US Patent No. 5,801,532. It can be moved by hand to a surface to be tested. A toroidal- shaped first resilient member contacts the bottom face of a support member. An elastic membrane extends over the bore of the first resilient member, contacts the bottom lateral surface of the first resilient member, and is unattached to the radially-inward-facing surface of the first resilient member. A more elastic, second resilient member is placed in the bore, is unattached to the first resilient member, and contacts the bottom surface of the elastic membrane. A flexible, surface-conformable, eddy current sensing coil overlies a portion of the bottom side of the second resilient member. The first resilient member is disclosed to comprise: a gel ring generally coaxially aligned with the longitudinal axis and attached to the first face of the base plate; a foam ring generally coaxially aligned with the longitudinal axis and longitudinally attached to the gel ring; and an annular rubber contact shield generally coaxially aligned with the longitudinal axis and longitudinally attached to the foam ring. Preferably, the gel ring consists essentially of RTV silicone, which has a Shore A durometer rating of 15 Shore A to 40 Shore, the foam ring consists essentially of neoprene sponge rubber (which is always more elastic than the foam ring).

[0012] The second resilient member, which is in contact with the sensing coil, has a coefficient of elasticity which is greater than that of the first resilient member. Therefore, the probe disclosed in US Patent No. 5,801,532 has a conformable holder, but the area of the probe that includes the sensing coils is quite stiff and would not be able to form to the shape being inspected. [0013] United States Patent No. 5,278,498 discloses a flexible core eddy current probe, again as opposed to an EC A, for testing of curved or regular surfaces. The core is comprised of a flexible binder loaded with a powdered magnetic material and then formed into a specific flexible core shape continuously adaptable to irregular or curved surfaces. The flexible core probe has specific application to carbon fiber reinforced composite components having contoured surfaces.

[0014] Flexible probes that are strap-like have been disclosed. These can be pressed into round-edged shapes, for example, pipeline, tube inspection, and aircraft. However, they are only useful for assessing wear and integrity of smooth surfaces and are subject to wear if used on hard edges or rough surfaces. They are also subject to differential pressure being exerted by the user as the user pushes on the flexible probe with their fingers.

[0015] A patent pending flexible probe array (FPA) (US Publication No. 20160025682) configured in a glove that can be worn by an inspector has been disclosed. The FPA conforms to the inspection surface and allows inspection of a wide region with each scan of the array. With this arrangement, the operator receives tactile feedback of surface profile changes and is able to adjust the pressure on the FPA to accommodate changing geometries. The FPA approach eliminates the need to maintain probe alignment and the raster scanning needed with a conventional probe. The system has been successfully demonstrated at four operating power plants. A major deficiency is that it relies heavily on the proficiency of the user and therefore there is a risk of human error. Further, the results would vary from operator to operator as there is no accurate feedback to the operator to ensure consistency between operators. In addition, the scan coverage on the glove is very small. Still further, the flexible probe would be ill suited for environments where there is dust, dirt and potentially an abrasive test surface.

[0016] Flexible eddy current array probes have been designed and used for assessing pipes both during manufacture and in the field. A T-probe, designed by Eddyfi has an encoder at the base of the T and the eddy current array sensors on the two arms of the probe. A user holds the probe on the arms and slides it over the surface being inspected. Similarly, they have an I- probe with the encoder at one end and the sensor along the remainder of the length.

[0017] EP-A-1 202 053 discloses eddy current inspection of a contoured surface of a workpiece by forming a backing piece of flexible, resiliently yieldable material with a contoured exterior surface conforming in shape to the workpiece contoured surface. It is apparent that the probe is shaped for the specific shape to be inspected and retains that shape.

[0018] EP 1 403 635 discloses a molded flexible eddy current array probe that is formed into a shape that conforms to a specific shape of article being inspected. It is clear that the flexible material has limited flexibility as integral anchors serve to retain the flexible material to the insert. A Shore A durometer rating of 20A to about 80A is cited, however, the example of a suitable flexible material is TC 5050 RTV compound, available from BJB Enterprises, Inc., 14791 Franklin Avenue, Tustin, CA 92780, which has a Shore A durometer hardness of 50A (equivalent to a pencil eraser).

[0019] United States Patent Application Publication Nos. 20210364472 and 20210349058 disclose a system and method for real-time visualization of a material during ultrasonic non-destructive testing. The system is capable of producing A-scans, B -scans, and C- scans of the test object and automatically highlighting potential foreign objects within the test object based on the scan data. The system includes a graphical user interface (GUI) capable of displaying a three-dimensional (3-D) image of a composite laminate constructed of a series of two-dimensional (2-D) cross sections. In one embodiment, the system includes an artificial intelligence module capable of highlighting foreign objects in order to provide size data, shape data, and/or depth data of the foreign object. It is disclosed that a robotic arm may be used. [0020] United States Patent Application Publication No. 20160320344 discloses a system for non-destructively characterizing laser welds that includes at least one phased array probe that includes a plurality of ultrasonic transducer elements arranged in an array at one end of the probe, wherein the transducer elements are operative to both generate ultrasonic signals and to receive reflections thereof, wherein the transducer elements are further arranged into discrete subgroups, and wherein each subgroup may be activated independently of the other subgroups and at different time intervals; a combination of materials for allowing the probe to conform to a contoured surface of a laser weld while enabling sound energy to be transferred directly into a laser weld under test conditions, wherein the combination of materials further includes a flexible membrane mounted on the end of the probe and a fluid filled chamber material disposed between the membrane and the array of ultrasonic transducer elements; and a data processor in communication with the at least one phased array probe that includes software having at least one imaging algorithm for processing data received from the probe and generating color coded ultrasonic C-scan images of a characterized laser weld. It is disclosed that the phased array probe may be mounted on a robot or other mechanical actuator.

[0021] In the mining and cement industry, very large gears are employed. For example, the girth gear in a mill has straight cut teeth and is about 3m to about 14m in diameter. The pinion gear drives the girth gear. It is much smaller, at about 0.5m to about 2m diameter. It has helix angles on the gear teeth. These gears cannot be readily removed and transported for testing. The helical gears are especially challenging as the gears are arranged in a helix with the angle of the teeth ranging between about 2 degrees to about 15 degrees. The addendum, dedendum and root of the gear teeth are all assessed.

[0022] What is needed therefore is an autonomous system and method suited to in situ testing to accurately and quickly identify anomalies or defects on the flanks (addendum and dedendum) and root of the gear teeth, including, but not limited to pits, scuffing, and cracks. The method would preferably not rely on visual inspection or human interaction. The device and method would also preferably be useful for different shapes and sizes of gear teeth, including helical gears. It would be advantageous if the system included a processor and memory for analyzing the data in real time, displaying the data and archiving the data.

SUMMARY OF THE INVENTION

[0023] The present disclosure provides an autonomous system and method suited to testing to accurately and quickly identify anomalies or defects on the flanks (addendum and dedendum) and root of the gear teeth, including, but not limited to pits, scuffing, and cracks. The method does not rely on visual inspection or human interaction. The device and method are useful for different shapes and sizes of gear teeth, including helical gears and can scan structures having complex geometries. The system includes a processor and memory for analyzing the data in real time, displaying the data and archiving the data.

[0024] In one embodiment, an autonomous non-destructive inspecting system is provided for inspecting gear teeth of open gear sets, the autonomous non-destructive inspecting system comprising: an eddy current array probe; a robotic device, the robotic device retaining the eddy current array probe and configured to move the eddy current array probe along a length of a gear tooth of an open gear; and a computer, the computer configured to instruct the robotic device to move the eddy current array probe and to receive a dataset from the robotic device. [0025] In the autonomous non-destructive inspecting system, the robotic device may include a base, and an articulating and extending arm which is attached to the base and retains the eddy current array probe.

[0026] In the autonomous non-destructive inspecting system, the base may be configured for mounting on a floor.

[0027] In the autonomous non-destructive inspecting system, the base may be configured for mounting on a gear guard.

[0028] In the autonomous non-destructive inspecting system, the computer may be configured to analyze the dataset.

[0029] In the autonomous non-destructive inspecting system, the eddy current array probe may be a flexible probe.

[0030] In another embodiment, an open gear set installation is provided, the open gear set installation including an open gear set, which includes a plurality of gears and a gear guard surrounding at least a portion of the plurality of gears and an autonomous non-destructive inspecting system comprising: an eddy current array probe; a robotic device, the robotic device retaining the eddy current array probe and configured to move the eddy current array probe along a length of a tooth of the gear, the robotic device attached to the gear guard or proximate to the gear guard; and a computer, the computer configured to instruct the robotic device to move the eddy current array probe and to receive a dataset from the robotic device.

[0031] In the open gear set installation the robotic device I may be a robotic arm attached to a base, the base attached to the gear guard.

[0032] In another embodiment, a method of autonomous non-destructive inspecting at least one tooth of a gear of a large open gear set is provided, the method comprising:

-selecting an autonomous non-destructive inspecting system comprising: an eddy current array probe; a robotic device, which retains the eddy current array probe; and a computer in communication with the robotic device;

-the computer instructing the robotic arm to place the eddy current array probe on the tooth and to scan a length of the tooth;

-the eddy current array probe sending a dataset to the computer; and -the computer analyzing the dataset. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic of the system of the present technology.

[0034] Figure 2 is a schematic of the robotic arm and probe, with the probe on a gear tooth.

[0035] Figure 3 is a schematic of an alternative embodiment robot.

[0036] Figure 4 is a schematic of an alternative embodiment robot.

[0037] Figure 5 is a block diagram of teaching the robot.

[0038] Figure 6 is a block diagram of the steps in autonomous inspection.

DETAILED DESCRIPTION OF THE INVENTION

[0039] Except as otherwise expressly provided, the following rules of interpretation apply to this specification (written description and claims): (a) all words used herein shall be construed to be of such gender or number (singular or plural) as the circumstances require; (b) the singular terms "a", "an", and "the", as used in the specification and the appended claims include plural references unless the context clearly dictates otherwise: (c) the antecedent term "about" applied to a recited range or value denotes an approximation within the deviation in the range or value known or expected in the art from the measurements method; (d) the words "herein", "hereby", "hereof", "hereto", "hereinbefore", and "hereinafter", and words of similar import, refer to this specification in its entirety and not to any particular paragraph, claim or other subdivision, unless otherwise specified; (e) descriptive headings are for convenience only and shall not control or affect the meaning or construction of any part of the specification; and (f) "or" and "any" are not exclusive and "include" and "including" are not limiting. Further, the terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted.

[0040] Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Where a specific range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is included therein. All smaller sub ranges are also included. The upper and lower limits of these smaller ranges are also included therein, subject to any specifically excluded limit in the stated range.

[0041] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the relevant art. Although any methods and materials similar or equivalent to those described herein can also be used, the acceptable methods and materials are now described.

[0042] Form-fitting - in the context of the present technology, form-fitting means that the shape of the device, and more specifically, the sensor area changes in response to different shapes of structures being inspected, for example, forming to the shape of one helical gear and then forming to the shape of a second helical gear. The form changes in situ.

[0043] In situ - in the context of the present technology, in situ refers to in place on the structure to be inspected.

[0044] Continuously adaptable - in the context of the present technology, continuously adaptable means that the sensor area, at least, can change form on the fly to conform to the surface being inspected. This can also be defined as variable shaped or having a variable shape or having a shape that can be varied.

[0045] Robotic device - in the context of the present technology a robotic device may be a robot or a robotic arm. It includes software or is controlled by software.

[0046] Autonomous robotic device - in the context of the present technology, an autonomous robotic device is one that does not require a human operator to function.

[0047] Autonomous non-destructive inspecting system - in the context of the present technology, an autonomous non-destructive inspecting system is one that does not require a human operator to function.

[0048] An autonomous non-destructive inspecting system, generally referred to as 10, for inspecting teeth of open gear sets is shown in Figure 1. The system 10 includes an eddy current array (ECA) probe 12, an autonomous robotic device 14 which releasably retains the ECA probe 12 and a computer 16 with a display 18. In an alternative embodiment, a phased array ultrasonic testing (PAUT) probe is used instead of the ECA probe 12. In yet another embodiment, both an ECA probe 12 and a PAUT probe are used. The inspecting system is designed for large open gear sets such as those used in mining and industrial milling operations. [0049] As shown in Figure 2, in one embodiment the autonomous robotic device is a robotic arm, generally referred to as 15, which is mounted on the gear guard 20. A portion of the gear guard is removed in the view of Figure 2 to provide access to the pair of meshing gears as shown in Figure 2. The robotic arm 14 can be seen extending to the gear, generally referred to as 22, where the ECA probe 12 is on a gear tooth 24. In another embodiment, as shown in Figure 3, the robotic arm 14 is floor mounted. In both embodiments, the robotic arm 14 is mounted on a base 26 and articulates, extends and retracts to place the probe 12 in contact with the gear teeth. In both embodiments, the autonomous robotic device is part of an autonomously inspected open gear set installation.

[0050] As shown in Figure 1, the robotic device 14 includes a microcontroller that is in wireless communication with the computer 16 or other computing device. Sensors, such as pressure sensors, may be included in the eddy current array probe 12 which communicate with the microcontroller and/or the computer to ensure that the correct contact is made between the eddy current array probe and the surface being examined.

[0051] As shown in Figure 4, in yet another embodiment, the robotic device 14 is a robot or autonomous vehicle, which includes an arm 15. In all embodiments, the robotic device 14 does not crawl or otherwise move on the surface that is contacted by the probe 12, but rather, remains largely outside of the mill. The robotic arm is able to move the probe 12 into contact with the gear from a location outside of the mill.

[0052] As shown in Figure 5, the autonomous robotic device 14 is trained utilizing a method like that shown in the flow chart of Figure 5. Initially, a human operator positions (step 200) the robotic device 14 such that the ECA probe 12 is in contact with a gear tooth 24 and then manually moves (step 202) the robotic device 14 such that the ECA probe 12 moves along the surface of the gear tooth 24 being inspected. The ECA probe 12 reports (step 204) a data set to the computer 16. The computer 16 analyses (step 206) the data set and if the data set is of an acceptable quality (as in the scanning was consistent, with no stopping and starting and at a suitable speed and the lift off was appropriate), the computer 16 sends (step 208) a positive report to the autonomous robotic device 14. The encoder of the ECA probe 12 sends (step 210) position data to the autonomous robotic device 14. The positive report is associated (step 212) with the position data. The process is repeated until the autonomous robotic device 14 has been trained. A test is then run (step 214) to ensure that the autonomous robotic device 14 can replicate the movement and force required in order to inspect the gear tooth 24. Once it is confirmed that the autonomous robotic device 14 is trained, a human operator is no longer required to be on site.

[0053] Figure 6 shows the steps of autonomous inspection in accordance with the method of the present disclosure. Although an exemplary method is shown, it should be understood that a variation of the method disclosure could be used in accordance with the present disclosure.

The robotic device 14 receives (step 300) an instruction from the computing device 16. The robotic device positions (step 302) the ECA probe 12 on a gear tooth 24. The robotic device 14 moves (step 304) the ECA probe along the gear tooth. If the ECA probe 12 is a flexible probe, the flank and root are scanned (step 306) in one pass. If the ECA probe 12 is a rigid probe, only one surface is scanned (step 308) in a pass. Each of the addendum, dedendum and root are assessed in the scanning step or steps. Multiple teeth can be inspected at one time by employing multiple robotic systems 10. The ECA probe 12 reports (step 310) a data set to the computer 16. The computing device 16 analyses (step 312) the data set and if the data set is of an acceptable quality (as in the scanning was consistent, with no stopping and starting and at a suitable speed and the lift off was appropriate), the computing device 16 sends (step 314) a positive report to the autonomous robotic device 14. The encoder of the ECA probe 12 sends (step 316) position data to the autonomous robotic device 14. The positive report is associated (step 318) with the position data. The data set is displayed (step 320) on the display 26 of the computing device 16 or another display that could be located remotely from the computing device 16. The robotic device 14, under control of the computing device 16, moves 322 to another gear tooth 24.

[0054] While example embodiments have been described in connection with what is presently considered to be an example of a possible most practical and/or suitable embodiment, it is to be understood that the descriptions are not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the example embodiment. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific example embodiments specifically described herein. Such equivalents are intended to be encompassed in the scope of the claims, if appended hereto or subsequently filed.

[0055] While example embodiments have been described in connection with what is presently considered to be an example of a possible most practical and/or suitable embodiment, it is to be understood that the descriptions are not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the example embodiment. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific example embodiments specifically described herein. Such equivalents are intended to be encompassed in the scope of the claims, if appended hereto or subsequently filed.