Patent Application
20170239775
The field of this disclosure relates generally to bore honing systems and, more particularly, to a system for honing a turbine or generator shaft.
At least some known power plants include a steam generator, a turbine, and an electrical generator. The steam generator boils water to generate steam, and the steam is channeled through the turbine. As the steam flows through the turbine, the steam drives a rotor of the turbine, which in turn drives the electrical generator to which the rotor is coupled.
The rotor typically has a shaft and a plurality of blades coupled to the shaft. Because the rotor blades and the rotor shaft experience thermal and mechanical stresses during operation of the turbine, it is desirable to periodically inspect the structural integrity of the rotor blades and the rotor shaft. At least some known inspection techniques include coupling a plurality of probes to the rotor shaft within a bore of the rotor shaft, and then transmitting electromagnetic energy through the rotor shaft via the probes to facilitate identifying structurally weakened areas of rotor shaft. Before attaching the probes, the bore of the rotor shaft is often honed using a tool that removes undesirable surface contours and/or build-up within the bore, thereby enabling better contact between the probes and the rotor shaft. However, at least some known honing techniques are overly time-consuming, which can delay the inspection process and cause the associated generator to be offline (and unable to generate electricity) for an undesirable length of time, resulting in a significant loss in revenue for the power plant.
In one aspect, a system for honing a shaft is provided. The system includes a rod having an axis and a head coupleable to the rod. The system also includes a drive motor coupleable to the rod such that the rod and the head are rotatable via the drive motor. The system further includes a linear actuator coupleable to the rod such that the rod and the head are translatable along the axis while being rotated via the drive motor.
In another aspect, a method for honing a shaft is provided. The method includes coupling an adapter to the shaft and operating a drive motor to rotate a rod having a head coupled thereto. The method also includes operating a linear actuator to translate the rod and the head along an axis of the rod while the rod and the head are rotated via the drive motor.
In another aspect, a drive assembly for rotating and translating a rod is provided. The drive assembly includes a drive motor, a servomotor, and at least one drive roller rotatably coupled to the drive motor. The drive assembly also includes at least one steering roller having a roller axis about which the at least one steering roller is rotatable. The at least one steering roller is coupled to the servomotor such that the at least one steering roller is pivotable via the servomotor about a pivot axis oriented substantially perpendicular to the roller axis. The at least one steering roller is spaced apart from the at least one drive roller to define a passage sized to receive the shaft.
The following detailed description illustrates shaft honing systems and methods by way of example and not by way of limitation. The description should enable one of ordinary skill in the art to make and use the honing systems, and the description describes several embodiments of the honing systems, including what is presently believed to be the best modes of making and using the honing systems. Exemplary honing systems are described herein as being useful for honing a turbine rotor shaft. However, it is contemplated that the honing systems have general application to a broad range of systems in a variety of fields other than turbines.
During operation of power plant 100, steam 108 flowing through turbine 104 causes rotor 112 to rotate (i.e., causes rotor blades 114 and rotor shaft 116 to rotate), which in turn causes generator drive shaft 122 to rotate. Generator 106 generates electricity as a result. Because rotor 112 experiences higher levels of thermal and mechanical stress during operation, it is commonplace to periodically test the structural integrity of rotor 112 (e.g., by manually inspecting the structural connection of rotor blades 114 to rotor shaft 116, and/or by electromagnetically inspecting the structural continuity of rotor shaft 116 using, for example, a plurality of probes (not shown) coupled to rotor shaft 116 within bore 118). However, it is typical for an inner surface 128 of rotor shaft 116, which defines bore 118, to have a contour and/or a level of build-up that makes it difficult to couple the probes to rotor shaft 116 within bore 118. As such, it is often desirable to hone (e.g., abrade and/or polish) inner surface 128 to enable a better connection between the probes and inner surface 128.
In the exemplary embodiment, system 200 includes a support assembly 206, a drive assembly 208 coupleable to support assembly 206, a honing head 210 coupleable to drive assembly 208, and a fluid supply assembly 212 coupleable to honing head 210. System 200 also includes a control unit 214 for operating support assembly 206, drive assembly 208, honing head 210, and/or fluid supply assembly 212 as described below. Optionally, system 200 may further include a sump 216, and/or a cleaning head 218 coupleable to drive assembly 208 in lieu of honing head 210. In other embodiments, system 200 may have any suitable number of head assemblies that are interchangeably coupleable to drive assembly 208 for any suitable purposes.
In the exemplary embodiment, support assembly 206 includes at least one pedestal (e.g., a first pedestal 220 and a second pedestal 222), at least one truss assembly (e.g., a first truss assembly 224 and a second truss assembly 226), a drive housing 228, a head housing 230, and an adapter 232. First pedestal 220 has a housing 234 seated on a plurality of casters 236. Each caster 236 is coupled to pedestal housing 234 via a ratchet mechanism 238 such that the vertical position of pedestal housing 234 relative to casters 236 is adjustable via ratchet mechanisms 238. Moreover, first pedestal 220 has a linear actuator 240 (e.g., a pneumatic linear actuator) contained at least in part within pedestal housing 234. Drive housing 228 is mounted to linear actuator 240 such that the vertical position of drive housing 228 relative to pedestal housing 234 is adjustable via linear actuator 240. Additionally, control unit 214 includes a computing device 242 and a user-interface 244, both of which are coupled to pedestal housing 234 such that user-interface 244 is accessible outside of pedestal housing 234. Computing device 242 is communicatively coupled to linear actuator 240 for operating linear actuator 240 in the manner described herein. In other embodiments, first pedestal 220 may have any suitable mechanism(s) for adjusting the vertical position of pedestal housing 234 and/or drive housing 228 in a manner that facilitates enabling system 200 to function as described herein.
In the exemplary embodiment, second pedestal 222 has a housing 246 seated on a plurality of casters 248. Each caster 248 is coupled to pedestal housing 246 via a ratchet mechanism 250 such that the vertical position of pedestal housing 246 relative to casters 248 is adjustable via ratchet mechanisms 250. Additionally, fluid supply assembly 212 includes a reel 252 and at least one fluid reservoir (e.g., a liquid reservoir 254 and a gas reservoir 256) positioned at least in part within pedestal housing 246. Moreover, fluid supply assembly 212 also includes at least one fluid conduit (e.g., a fluid conduit bundle 258 having at least one liquid conduit 260 coupled in flow communication with liquid reservoir 254 and at least one gas conduit 262 coupled in flow communication with gas reservoir 256). Conduits 260 and 262 are wound about reel 252, and reel 252 is spring-biased to continuously impart a retracting (or winding) force to conduits 260 and 262 such that conduits 260 and 262 are unwindable from reel 252 as desired by imparting a pulling force to conduits 260 and 262 that overcomes the retracting force of reel 252. Optionally, second pedestal 222 may have a linear actuator (not shown) (e.g., a pneumatic linear actuator like linear actuator 240) communicatively coupled to computing device 242 to facilitate adjusting the vertical position of truss assemblies 224 and 226 relative to pedestal housing 246. Second pedestal 222 may also include at least one pump 255 for supplying liquid and/or gas from liquid reservoir 254 and/or gas reservoir 256, respectively, to honing head 210 and/or cleaning head 218, as set forth in more detail below.
In the exemplary embodiment, first truss assembly 224 includes a first truss 264, a first bracket 266, and a first rail 268. First truss 264 has a first end 270 and a second end 272. First rail 268 is coupled to first truss 264 between first end 270 and second end 272, and first bracket 266 is coupled to drive housing 228. Similarly, second truss assembly 226 includes a second truss 274, a second bracket 276, and a second rail 278. Second truss 274 has a first end 280 and a second end 282, and second rail 278 is coupled to second truss 274 between first end 280 and second end 282. Second bracket 276 has a conduit roller 284 and is mounted to pedestal housing 246 such that second bracket 276 projects from pedestal housing 246.
First end 270 of first truss 264 is coupleable to first bracket 266 via a plurality of pins 286, and second end 272 of first truss 264 is coupleable to first end 280 of second truss 274 via a plurality of pins 286. Likewise, second end 282 of second truss 274 is coupleable to second bracket 276 via a plurality of pins 286. First truss 264 and second truss 274 thereby collectively extend between first pedestal 220 and second pedestal 222, such that first rail 268 and second rail 278 are aligned with one another. Notably, pins 286 are of the quick-release type, in that pins 286 are manually removable via a pulling action to facilitate easier disassembly of first truss 264 and second truss 274. Moreover, first truss 264 and second truss 274 are fabricated at least in part from a composite material (e.g., a carbon fiber material) to facilitate reducing their overall weight, thereby enhancing the portability of system 200. In other embodiments, support assembly 206 may have any suitable number of pedestals and/or trusses (e.g., support assembly 206 may have only one pedestal and/or only one truss). For example, in some embodiments, support assembly 206 may have three or more trusses (e.g., five trusses) that are coupleable together via pins 286.
In the exemplary embodiment, drive assembly 208 includes a shuttle 288, a rod 290, a rod rotating unit 292, and a linear actuator 294. Shuttle 288 is coupleable to rails 268 and 278 such that shuttle 288 is slidable along rails 268 and 278 (and, therefore, along trusses 264 and 274). Moreover, shuttle 288 includes a conduit joint 296 having a first joint segment 298 and a second joint segment 300 coupled to first joint segment 298 such that first joint segment 298 is rotatable relative to second joint segment 300. Rod 290 has a plurality of sections 302 (e.g., five rod sections 302) that are coupleable together (e.g., via threaded engagement(s) 304) to extend the length of rod 290 as desired, such that the section(s) 302 define a first end 306 and a second end 308 of rod 290. Notably, each rod section 302 has at least one internal conduit section 310 extending along its length such that, when rod sections 302 are coupled together, rod 290 defines at least one internal conduit 312 that extends from rod first end 306 to rod second end 308. In other embodiments, rod 290 may not have a plurality of detachable sections 302 but, rather, may be a single, unitary structure between first end 306 and second end 308.
In the exemplary embodiment, rod first end 306 has a first mount 314, and rod second end 308 has a second mount 316. Second mount 316 is coupleable to first joint segment 298 of conduit joint 296, and first mount 314 is coupleable to honing head 210 and cleaning head 218 such that rod 290 extends through head housing 230 and drive housing 228, and along first truss assembly 224 and second truss assembly 226. As such, rod 290 extends between rod rotating unit 292 and linear actuator 294 within drive housing 228. More specifically, as set forth in more detail below, rod rotating unit 292 includes at least one drive motor 318 and a drive roller assembly 320 rotatably coupled thereto via a suitable arrangement of gears (not shown), and linear actuator 294 includes at least one servomotor 322 and a steering roller assembly 326 pivotably coupled thereto via a suitable arrangement of gears (not shown). Drive motor 318 and servomotor 322 are communicatively coupled to computing device 242.
In the exemplary embodiment, adapter 232 includes a flange 328 and is coupled to head housing 230 at a bearing 330 such that adapter 232 is rotatable relative to head housing 230. Head housing 230 defines an interior space 332 sized to receive honing head 210 and cleaning head 218. Moreover, head housing 230 defines at least one window 334 sized to permit insertion of honing head 210 and cleaning head 218 into interior space 332 for detachably and interchangeably coupling honing head 210 and cleaning head 218 to rod 290 via window(s) 334. Additionally, head housing 230 has at least one aperture 335 for draining liquid from interior space 332 into sump 216, which is positionable beneath head housing 230. In other embodiments, head housing 230 may not have window(s) 334 and/or aperture(s) 335.
In the exemplary embodiment, honing head 210 includes a shell 336 coupleable to rod 290 at first mount 314, a pneumatic actuator 338 contained within shell 336, a plurality of honing elements 340 (e.g., abrasive elements such as, for example, stones or other natural abrasives) coupled to pneumatic actuator 338 within shell 336, and a plurality of nozzles 342 coupled to shell 336 and oriented to discharge liquid away from shell 336 as described below. Notably, pneumatic actuator 338 is communicatively coupled to computing device 242 for increasing and/or decreasing the length by which honing elements 340 extend from shell 336, thereby enabling honing elements 340 to be selectively protracted away from shell 336 and selectively retracted towards shell 336 as desired. In other embodiments, honing head 210 may have any suitable number of honing element(s) 340 and/or nozzle(s) 342 arranged in any suitable manner that facilitates enabling system 200 to function as described herein (e.g., honing head 210 may have only one honing element 340 and/or only one nozzle 342). Similarly, cleaning head 218 includes a shell 344 coupleable to rod 290 at first mount 314, and a plurality of nozzles 346 coupled to shell 344 and oriented to discharge liquid away from shell 344 as described below.
In the exemplary embodiment, steering roller assembly 326 includes at least one steering roller (e.g., a first steering roller 358 and a second steering roller 360) positionable against rod 290 such that steering rollers 358 and 360 impart a downward force on rod 290 to firmly seat rod 290 against drive rollers 350 and 352. Thus, when rod 290 is rotated by drive rollers 350 and 352, steering rollers 358 and 360 are caused to rotate in the same direction as drive rollers 350 and 352 (and rod 290) as a result of steering rollers 358 and 360 being in contact with rod 290. First steering roller 358 has a roller axis 362 such that first steering roller 358 is rotatable about roller axis 362. Moreover, first steering roller 358 is coupled to servomotor 322 such that first steering roller 358 is pivotable about a pivot axis 364 oriented substantially perpendicular to roller axis 362. Similarly, second steering roller 360 has a roller axis 366 such that second steering roller 360 is rotatable about roller axis 366, and second steering roller 360 is coupled to servomotor 322 such that second steering roller 360 is pivotable about a pivot axis 368 oriented substantially perpendicular to roller axis 366. First steering roller 358 and second steering roller 360 (as shown in
As such, drive assembly 208 has three different states of operation, namely: (1) a first state of operation (as shown in
Thus, drive motor 318 is operable via computing device 242 to vary the speed (and optionally the direction) at which rod 290 rotates about rod axis 356, while servomotor 322 is operable via computing device 242 to vary the direction in which rod 290 translates along rod axis 356. For example, the frequency of the back-and-forth oscillation of rod 290 along rod axis 356 is controllable via computing device 242 (e.g., via wireless limit switches communicatively coupled to computing device 242) to control the length of each backward stroke and each forward stroke of rod 290 in a manner that suits a desired honing pattern. Notably, by virtue of functioning as threads for translating rod 290 forward and/or backward along rod axis 356, steering rollers 358 and 360 enable linear actuator 294 to function as a mechanical linear actuator by mechanically converting the rotational motion of rod 290 into linear motion of rod 290. In other embodiments, however, linear actuator 294 may be of any suitable type (e.g., a pneumatic linear actuator, a hydraulic linear actuator, an electric linear actuator, etc.) that does not utilize the rotational motion of rod 290 to displace rod 290 linearly.
Referring back to
With adapter 232 coupled to flange 126, drive assembly 208 is operable to rotate and translate honing head 210 forward from head housing 230 into bore 118 of rotor shaft 116. Pneumatic actuator 338 is then operable via computing device 242 to draw gas (not shown) from gas reservoir 256 across gas conduit 262 and an internal conduit 312 of rod 290 for pneumatically protracting honing elements 340 away from shell 336 and into contact with inner surface 128 of rotor shaft 116. Additionally, the pump 255 associated with liquid reservoir 254 is also operable via computing device 242 to supply honing liquid (not shown) from liquid reservoir 254 to honing head 210 via liquid conduit 260 and an internal conduit 312 of rod 290 for discharging the honing liquid from nozzles 342 onto inner surface 128 of rotor shaft 116.
With honing elements 340 seated against inner surface 128 and the honing liquid being discharged onto inner surface 128, drive assembly 208 is operable via computing device 242 to oscillate rod 290 (and honing head 210) back-and-forth inside bore 118 of rotor shaft 116 as described above. Thus, inner surface 128 is honed (i.e., abraded and/or polished) in an automated manner (i.e., rod 290 is not manually walked or pushed/pulled back-and-forth within bore 118). During the honing operation, the honing liquid drains from bore 118 into sump 216 via aperture(s) 335 of head housing 230, thereby removing debris generated by honing elements 340 inside bore 118. Moreover, the honing liquid also facilitates cooling the interface between honing elements 340 and inner surface 128 during the honing operation. Optionally, sump 216 may be coupled in flow communication with liquid reservoir 254 via suitable conduit(s) (not shown) such that, after the honing liquid collected within sump 216 is filtered (either inside sump 216 or by a separate filtration assembly (not shown) coupled to sump 216), the filtered honing liquid is then recirculated to liquid reservoir 254 for reuse.
As honing head 210 oscillates back-and-forth within bore 118, shuttle 288 is displaced along rails 268 and 278, while rod 290 rotates relative to shuttle 288 at conduit joint 296. Notably, drive motor 318 remains stationary when rod 290 oscillates back-and-forth. Additionally, because reel 252 is spring-biased to retract conduit bundle 258, reel 252 releases additional lengths of conduit bundle 258 with each forward stroke of rod 290, and winds excess lengths of conduit bundle 258 with each backward stroke of rod 290. Moreover, because adapter 232 is rotatable relative to head housing 230 via bearing 330, rotor 112 is rotatable during the honing operation to enable simultaneous inspection of rotor blades 114 and/or their attachment to rotor shaft 116. Optionally, additional rod sections 302 may be inserted to increase the length of rod 290 when honing longer rotor shafts, and additional trusses may likewise be inserted between first truss 264 and second truss 274 via pins 286 to suit the increased length of rod 290.
After inner surface 128 is adequately honed via honing head 210, pneumatic actuator 338 is operated via computing device 242 to retract honing elements 340 away from inner surface 128 and towards shell 336, and drive assembly 208 is then operated via computing device 242 to retract rod 290 backward for repositioning honing head 210 inside interior space 332 of head housing 230. Honing head 210 is then detachable from first mount 314 for removal from head housing 230 via window(s) 334. Subsequently, cleaning head 218 may be inserted into interior space 332 of head housing 230 via window(s) 334 for coupling cleaning head 218 to first mount 314. Drive assembly 208 may then be operated to translate cleaning head 218 forward into bore 118, for discharging cleaning liquid from nozzles 346 onto inner surface 128 and then draining the discharged cleaning liquid (and associated debris suspended therein) from bore 118 into sump 216. Optionally, the cleaning liquid may be contained within liquid reservoir 254 and supplied to cleaning head 218 via the associated pump 255, or the cleaning liquid may be suitably contained in a third reservoir (not shown) and supplied via another pump (not shown), both of which may be positioned within housing 246 of second pedestal 222.
After honing and cleaning inner surface 128 of rotor shaft 116 as desired, adapter 232 may then be uncoupled from flange 126, and pedestals 220 and 222 rolled away from rotor 112 (via their respective casters 236 and 248), and/or drive assembly 208 may be lowered (e.g., via ratchet mechanisms 238 and/or 250, and/or linear actuator 240) to permit the insertion of a borescope into bore 118 for inspecting bore 118. Moreover, the probes for use in inspecting rotor shaft 116 may then be inserted into bore 118 and coupled to inner surface 128 for conducting a more effective inspection of rotor shaft 116. Notably, system 200 is easily disassembled (e.g., via quick-release pins 286, threaded engagements 304, etc.), and is easily transportable due at least in part to its lighter weight that results from trusses 264 and 274 being made at least in part from a composite material (e.g., a carbon fiber material).
Some embodiments involve the use of one or more electronic or computing devices. Such devices typically include a controller or processing device such as a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a reduced instruction set computer (RISC) processor, an application specific integrated circuit (ASIC), a programmable logic circuit (PLC), a field programmable gate array (FPGA), a digital signal processing (DSP) device, and/or any other circuit or processing device capable of executing the functions described herein. The methods described herein may be encoded as executable instructions embodied in a computer readable medium, including, without limitation, a storage device and/or a memory device. Such instructions, when executed by the controller or processing device, cause the controller or processing device to perform at least some of the method steps described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the terms controller and processing device.
The above-described embodiments include at least the following technical effects: (1) providing systems and methods for more effectively and efficiently honing a shaft such as, for example, a turbine rotor shaft; (2) providing shaft honing systems that are more easily assembled and disassembled; and (3) providing shaft honing systems that are more easily transported to a shaft inspection site.
The methods and systems described herein facilitate honing a shaft such as, for example, a turbine rotor shaft. More specifically, the methods and systems facilitate honing the inner surface of a turbine rotor shaft in advance of inspecting the turbine rotor shaft. For example, the methods and systems facilitate honing a turbine rotor shaft in a more automated manner, thereby reducing the time needed to hone the turbine rotor shaft. Additionally, the methods and systems facilitate providing a honing system that is more easily assembled and disassembled at the inspection site, and is more easily transported to and from the inspection site. As a result, the methods and systems facilitate reducing the amount of time that the associated electrical generator is offline, which in turn reduces the cost associated with inspecting the rotor of the associated turbine. This reduces the amount of revenue lost by the power plant as a result of the turbine rotor inspection process.
Exemplary embodiments of shaft honing systems and methods are described above in detail. The systems and methods described herein are not limited to the specific embodiments described herein, but rather, components of the systems and methods may be utilized independently and separately from other components described herein. For example, the systems and methods described herein may have other applications not limited to practice with turbines, as described herein. Rather, the systems and methods described herein can be implemented and utilized in connection with various other industries.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
