Patent Publication Number: US-2013232792-A1

Title: Apparatus and method for servicing turbomachinery components in-situ

Description:
BACKGROUND OF THE INVENTION 
     The apparatus and method described herein relate generally to turbomachinery. More specifically, the apparatus and method relate to servicing or repairing turbomachinery components in-situ. 
     Turbine compressor blades can get damaged due to effects such as corrosion, rub cracks, pitting, and foreign objects. In the event of such damage, timely detection and repair of these blades are desirable to prevent tip liberation and subsequent compressor failure. The current practice for blade repair requires compressor case removal, which is inevitably time consuming and expensive. The removal of the compressor case for repair of compressor blades also creates undesirable outage time, thereby resulting in lost revenue for the machine owner/operator. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In an aspect of the present invention, an apparatus adapted for servicing a turbomachine component includes a tool delivery mechanism adapted for delivering a tool to a desired location in a turbomachine. A tool support is adapted to be secured onto the body of the turbomachine, and is also configured to support the tool delivery mechanism. A machining tool is attached to the tool delivery mechanism, and includes an axial slide clamp configured to clamp to the turbomachine component, a radial slide slidably connected to the axial slide clamp, a spring connected to the axial slide clamp and the radial slide, the spring providing axial tension, and a machining bit retained at least partially within the radial slide. The apparatus is adapted to service the component of the turbomachine in-situ. 
     In another aspect of the present invention, an apparatus is provided for servicing a turbomachine component. The apparatus includes a machining tool having an axial slide clamp configured to clamp to the turbomachine component, a radial slide slidably connected to the axial slide clamp, a spring connected to the axial slide clamp and the radial slide, the spring providing axial tension, and a machining bit retained at least partially within the radial slide. The apparatus is adapted to service the component of the turbomachine in-situ. 
     In yet another aspect of the present invention, a method is provided including the steps of adjusting an orientation of inlet guide vanes, adjusting a rotor/stator clocking, moving the tool delivery mechanism into a first desired position, rotating the tool delivery mechanism into a second desired position, attaching a machining tool to a component of the turbomachine, and manipulating a handle to move the machining tool repair the component. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a partial, cut-away view of a turbomachine; 
         FIG. 2  illustrates a partial perspective view of a compressor showing the airfoils and vanes; 
         FIG. 3  illustrates examples of tip cropping performed on a compressor blade; 
         FIG. 4  illustrates a side view of the end effector of a machining tool that may be used to repair or machine a component, according to an aspect of the present invention; 
         FIG. 5  illustrates a simplified view of an axial slide clamp, according to an aspect of the present invention; 
         FIG. 6  illustrates a simplified view of an axial slide clamp, according to an aspect of the present invention; 
         FIG. 7  illustrates a perspective view of a tool delivery mechanism, according to an aspect of the present invention; 
         FIG. 8  illustrates a schematic view of the tool delivery mechanism and machining tool navigating through various rotor and stator stages in a compressor, according to an aspect of the present invention; 
         FIG. 9  illustrates an end view of the machining tool of  FIG. 4  attached to or secured onto a component of a turbomachine, according to an aspect of the present invention; 
         FIG. 10  illustrates a perspective view of a tool delivery mechanism, according to an aspect of the present invention; and 
         FIG. 11  illustrates a method of repairing a turbomachine component, according to an aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One or more specific aspects/embodiments of the present invention will be described below. In an effort to provide a concise description of these aspects/embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with machine-related, system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. Additionally, it should be understood that references to “one embodiment”, “one aspect” or “an embodiment” or “an aspect” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments or aspects that also incorporate the recited features. 
     A turbomachine is defined as a machine that transfers energy between a rotor and a fluid or vice-versa, including but not limited to a gas turbine, a steam turbine and a compressor. Turbomachinery is defined as one or more machines that transfer energy between a rotor and a fluid or vice-versa, including but not limited to gas turbines, steam turbines and compressors. The major challenge in the development of an in-situ blade or vane repair method and apparatus is to design a mechanism that can deliver the repair payloads to the target blade or vane inside the compressor, due to the stringent spatial constraints imposed by the tight workspace within the compressor flow path. The delivery mechanism should be capable of reaching both the leading edges and the trailing edges of the target vane, airfoil or blade (e.g., the second row of compressor rotor blades (R1) or vanes (S1)). 
       FIG. 1  illustrates a partial, cut-away view of a turbomachine  100 , which may be a gas turbine compressor. However, it is to be understood that the present invention can be applied to any turbomachine, including but not limited to, gas turbines, steam turbines, compressors, etc. In turbomachine  100 , half of the bell mouth  110  is omitted for clarity to show some of the vanes and blades inside. The first stage of stator vanes is called the inlet guide vanes (IGVs)  120 . The bell mouth  110  includes an outer surface  112  and an inner surface  114 , and incoming flow (e.g., air) passes between these two surfaces. Typically, a plurality of support members  116  are fastened or welded to the outer surface  112  and the inner surface  114  for support. 
       FIG. 2  illustrates a partial perspective view of compressor airfoils and vanes, with the casing omitted for clarity. The stator vanes are generally fixed, while the rotor airfoils/blades are connected to rotatable rotor  204 . The inlet guide vanes  120  are generally fixed as well, but may pitch around a generally radial axis to vary the direction or amount of incoming flow. The inlet guide vanes  120  are followed by a first row of rotor airfoils  230 . The airfoils can also be referred to as the R0 airfoils or blades, as they are part of the R0 stage. The stator vanes  240  are next, and can also be referred to as the S0 vanes, as they are part of the S0 stage. The next row of rotor airfoils/blades  250  can be referred to as the R1 airfoils or blades, as they are part of the R1 stage. The R1 airfoils are followed by the S1 stator vanes  260 , as they are part of the S1 stage, and so on. 
     It would be desirable if a delivery mechanism could go through the bell mouth  110  and reach the target blade or vane, as well as deliver a desired tool set to perform the desired repair operation. As one example only, an R1 blade can experience various types of damage and this blade could be reached without requiring case removal, according to an aspect of the present invention. 
       FIG. 3  illustrates a few examples of tip cropping repairs for an R1 blade, however, this type of repair could be applied to any blade or vane as desired in the specific application. The damage could be caused by corrosion, cracks, fatigue and/or pitting, as just a few examples. Therefore, according to the damages that typically occur to an R1 blade, three types of blending operations are identified and defined as shown in  FIG. 3 . Blade  310  illustrates a Type 1 blend, where a portion of the blade tip is removed. In this example, the maximum amount of D is equal to half of the chord length (CL), and the maximum amount of C is equal to one third of the blade length (BL). Blade  320  illustrates a Type 2 blend, where a maximum amount of E×F is equal to a predetermined amount and R is equal to a corner radius of about 0.25″. Blade  330  illustrates an edge blend, where A is greater than five times the distance of X (the chord depth of the damage). Accordingly, any specific amount and/or distance can be used as desired in the specific application, and the values given previously are merely exemplary. In addition, the Type 1, Type 2 and Type 3 blends may be located on the blade leading edge  311  and/or trailing edge  312 . Other types of blends and repairs, including full tip crops, may also be completed by the present invention. 
       FIG. 4  illustrates a partial side view of a machining tool  400  (or apparatus), according to an aspect of the present invention. The machining tool  400  is configured to clamp onto a turbomachine component  410 , such as a rotor blade, stator vane or rotor airfoil, and then machine a desired area of the component. The axial slide clamp  420  is disposed on both sides of component  410 , and only one side of axial slide clamp is shown in  FIG. 4 . The axial slide clamp includes one or more generally axially extending slots  422  and  424 . A tension applying device  426 , such as a screw or clamp, is configured to clamp both sides of axial slide clamp  420  onto component  410 . 
     A radial slide  430  is slidably connected to axial slide clamp  420 , by one or more projections (not shown in  FIG. 4 ) that extend into generally axially extending slots  422  and  424 . The axially extending slots  422  are configured to permit axial movement of the radial slide  430 . The projections may be cylindrical or rectangular in shape, or any other shape as desired in the specific application. The radial slide  430  also includes at least one generally radially extending slot  432  that is configured to permit radial movement of a machining bit  440 . The radially extending slots  432  serve as stoppers or guides for the grinding bit  440 , and the clamp  420  geometry (or shape) will change depending on the type of repair (e.g. square, rectangular, triangular or curvilinear) for repair as shown in the few non-limiting examples in  FIG. 3 . As shown in  FIG. 4 , the axial slide clamp  420  is configured for a Type 2 or rectangular shaped crop/repair. The radial direction is generally indicated by arrow  401  and the axial direction is generally indicated by arrow  402 , and these directions generally translate to radial and axial directions of the turbomachine. 
     A spring  450  is connected to both the axial slide clamp  420  and the radial slide  430 , and provides axial tension between both elements. The spring  450  pulls the machining bit  440  toward the surface of component  410  so that the bit  440  contacts the surface of component  410  during a machining operation. For example, during a machining operation when the machining bit  440  is a grinding bit, the spring  450  pulls radial slide  430  axially toward the component  410  as the grinding bit grinds away the desired portion of component  410 . The tool bit  440  may also comprise a sander, polisher, marking device, pen, or any other suitable tool that may be desired in the specific application. 
       FIG. 5  illustrates an axial slide clamp  520  configured for a Type 1, or triangular, repair. The component  510  will have the triangular portion  511  removed after a repair or machining operation. The slots  522  and  524  are used by the radial slide (not shown in  FIG. 5 ).  FIG. 6  illustrates an axial slide clamp  620  configured for a Type 3, or curvilinear repair. The component  610  will have the semi-oval shaped portion  611  removed after a repair or machining operation. The slots  622  and  624  are used by the radial slide (not shown in  FIG. 6 ). 
       FIG. 7  illustrates a perspective view of a tool delivery mechanism  700  attached to the machining tool  400 . The tool delivery mechanism  700  may be used to deliver a machining or repair tool (e.g., a grinder) into a turbine or compressor to reach the target blade or vane. As described earlier, a major challenge in the design of the tool delivery mechanism  700  is due to the stringent spatial constraints imposed by the tight workspace within the turbine or compressor flow path. In addition, there are an infinite number of possible clocking configurations of the first few rows of compressor blades/vanes, due to two uncertainties in clocking between different rows of blades/vanes. In particular, the clocking between the rotor and the stator can be arbitrary and the clocking between the 1 st  stage and the 2 nd  stage of rotor blades can be very different from one unit of a turbomachine to another. As the rotor/stator clocking is tunable (i.e., the rotor airfoils/blades can be turned relative to the stationary stator vanes), it can be strategically adjusted to facilitate the ingress/egress of the tool delivery mechanism  700 , whereas the multiple rotor stage (e.g., R0/R1) clocking is fixed and therefore not controllable as it varies from one machine to another machine. The tool delivery mechanism  700  is thus designed to be capable of accomplishing all the three types of blends on airfoils, blades and vanes in various stages with various clocking settings or arrangements. 
     The tool delivery mechanism  700  includes a two-link mechanism that has been specifically designed to facilitate tool delivery. The tool delivery mechanism  700  includes a handle  710 , a middle link  720  which includes two rods which may include a first rod  722  and a second rotary rod  724 , and an end effector  730 . A universal joint  740  is attached to each end of the first rod  722 , and rotary (or second) rod  724 . Thus four universal joints  740  may be employed in the tool delivery mechanism  700 . The two rods  722 ,  724 , with universal joints  740  at both ends are then assembled substantially parallel to each other and are attached to two end plates  752 ,  754 . The handle  710  is attached to end plate  752 , and the end effector  730  is attached to end plate  754 . The terms “joint” or “joints” may be defined to include a universal joint and/or a ball joint, and universal joints and/or ball joints, respectively. 
     The machining tool includes two axial slide clamps  420  and a machining apparatus  441  driving the machining bit  440 . In one example, the machining apparatus  441  is a motor that imparts rotational motion to bit  440 . The motor could be an air (e.g., pneumatic) or electric powered motor, or any other suitable motor as desired in the specific application. The bit  440  could be any suitable abrasive media or material (e.g., a grinder, a sander, a polisher or also a marking device or pen). The machining apparatus  441  (and machining bit  440 ) are manipulated through a cable  760  that is attached at one end to a machining apparatus guiding rail  761 , and at the opposing end to cable handle  762 . An operator can push or pull the cable to move the machining apparatus  741 , and this motion translates to movement of the machining bit  440 . One or more springs  750  may be connected to the machining apparatus  441  to facilitate movement of the machining apparatus. This configuration allows the operator to control the speed of movement and the location of the machining bit  440  relative to the surface of component  410 . 
     According to an aspect of the present invention, and referring to  FIG. 8 , a method is provided to insert the tool delivery mechanism  700  inside a turbomachine, e.g., a compressor, for repairing a part in the turbomachine. A first step can include adjusting the inlet guide vane  120  orientation, and this step may be followed or preceded by adjusting the rotor/stator clocking to facilitate the ingress/egress of the tool delivery mechanism  700 . In order to insert the tool delivery mechanism  700  into the compressor  100  and perform the servicing/repair operation, the inlet guide vanes  120  may be oriented so that they are about parallel to the R0 blades  230 . The relative clocking of rotor and stator may be adjusted so that the trailing edge, in this example, of the associated R0 blade  832  is in close proximity to the leading edge of an S0 vane  841 . The associated R0 blade  832  is the blade that the target R1 blade  851  is circumferentially clocked in between the R0 blade  831  and the next R0 blade  833  in clockwise direction. After the associated R0 blade  832  is identified and its trailing edge is aligned with the leading edge of S0 vane  841 , there will be two full openings at the S0 stage available for the insertion of the tool delivery mechanism  700 . 
     During the insertion of the tool delivery mechanism  700 , the 2-link mechanism is first oriented so that the end effector  730  is substantially radially aligned with the compressor and the middle link  720  is substantially parallel to the IGVs. To be more specific, the end effector  730  will be pointing substantially out of the page as in the view of  FIG. 8 . Then the tool delivery mechanism  800  can slide easily into the compressor until it reaches the desired position (e.g., the S0 or R1 stage). Then the tool delivery mechanism  700  can be rotated about 90 degrees and be placed in the configuration as shown in  FIG. 8 . 
       FIG. 9  illustrates a simplified end view of the machining tool clamped onto a component  410 . The axial slide clamps  420  are clamped onto component  410  by the use of threaded rod  426  and fastener  427  (e.g., a nut or an internally threaded bore). The threaded rod may be rotated by actuation of knob  770 , which in turn rotates the rotary rod  724  which is connected via suitable gearing and connectors to threaded rod  426 . The radial slides  430  retain and guide bit  440 , so that the bit may be moved up and down (as shown in  FIG. 9 ) by the use of cable  760 . The grinding portion of the bit  440  may be confined only to that portion of the bit  440  that will be in contact with the component  410 . The sections of bit  440  that will be in contact with the clamps  420 , which function as stoppers/guides providing the shape of the repair needed (e.g. rectangular or square for repair  320 ), will be flat or smooth to avoid grinding of clamps  420 . 
       FIG. 10  illustrates a perspective view of another tool delivery mechanism and machining tool, according to an aspect of the present invention. The tool delivery mechanism  1000  includes middle link  1020  having two rods  1022  and  1024 , end effector  1030  and knob  1070 . The tool delivery mechanism is supported by tool support  1080  which has a base  1081  and support member  1082 . The base  1081  may include magnetic devices or can be configured to be non-magnetic. The base is placed on a surface of the bell mouth  110 . A motor  1041 , which may be pneumatic or electrical, is connected to a shaft or conduit  1060 . This shaft or conduit  1060  extends to a machining tool  1090  located at the distal end of the tool delivery mechanism. The machining tool (which may be similar to machining tool  400 ) is clamped to or placed near a component  410 . 
       FIG. 11  illustrates a method  1100  of repairing a turbomachine component according to an aspect of the present invention. The method  1100  includes a step  1110  of adjusting an orientation of inlet guide vanes, a step  1120  of adjusting a rotor/stator clocking, a step  1130  of moving the tool delivery mechanism into a first desired position, a step  1140  of rotating the tool delivery mechanism into a second desired position, a step  1150  of attaching a machining tool to a component of the turbomachine, and a step  1160  of manipulating a handle to move the end effector to at least one of: inspect, mark and repair a component in a turbomachine. The above method can also include orienting a middle link of the tool delivery mechanism so that the middle link is substantially parallel to inlet guide vanes, and subsequently moving the end effector into position near at least one of: an S0 vane, an S1 vane, an R0 blade and an R1 blade. Another step may include monitoring the insertion of the machining tool as well as monitoring the repair process, and this may be accomplished by the use of a borescope video imaging device (not shown). The method can also include the step of performing at least one of a Type 1, Type 2 and a Type 3 in-situ repair on at least one of an S0 vane, an S1 vane, an R0 blade and an R1 blade. 
     One important feature for the mechanical design of the tool delivery mechanism  700  is that the whole system should have adequate rigidity to withstand the varying forces produced during the repair or grinding operations. For example, experience has shown that grinding forces may be up to about 30 lbf or more in all directions and within a wide spectrum (0˜about 500 Hz and up). Insufficient rigidity of the system will result in chattering during grinding operation, reducing machining accuracy and maneuverability. The positioning uncertainty at the end of the grinding head should be less than a predetermined distance at a nominal 30 lbf machining load to assure machining accuracy. In the ideal case, the location of the grinder head should be primarily determined by the orientation of the handle  510  and the cable  760 /handle  762 . However, due to the flexibility of each mechanical component in the tool delivery mechanism  700 , and the backlashes in the joints, including both the universal joints  740  and the prismatic joint of the end effector  730 , the tool head location may vary under machining loads even though the operator does not intend to vary it. Therefore component stiffness and joint backlashes are important considerations in designing and implementing the tool delivery mechanism  500 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.