Balance weight entry ports for turbine rotors

Abstract

To provide a turbine rotor which includes a rotor body and a balancing weight slot defined in an exterior circumference of the body.SOLUTION: A turbine rotor includes a rotor body (112) and a balancing weight slot (122) defined in an exterior circumference (244) of the body. The balancing weight slot (122) has a first axial width (W1) and a first radially outward facing surface (134) at a first radial distance (RD1) from a rotor axis (A). The rotor also includes a balancing weight entry port (142) defined in a portion of the exterior circumference (244) of the rotor body (112), aligned with the balancing weight slot (122). Balancing weight entry port (142) has a second axial width (W2) greater than the first axial width, and a second radially outward facing surface (238) at a second radial distance (RD2) from the axis of the rotor body (112) smaller than the first radial distance.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates generally to turbomachines, and more particularly to turbine rotors including balance weight entry ports for introducing weights into balance weight slots in the turbine rotor, tools for creating the ports, and related methods. [Background technology]

[0002] Certain rotating components of industrial machines, such as turbine rotors, include balance weights coupled to circumferential slots on the turbine rotor's outer circumferential surface. The circumferential slots have a cross-sectional shape that includes retaining members, such as tabs or ears, that retain one or more weights with similar cross-sectional shapes. The circumferential slots can have, for example, a dovetail or trapezoidal cross-sectional shape. The weights can be slid along the slot to any circumferential position needed to balance the turbine rotor and are fixed in place. To introduce the weight into the slot, a balance weight entry port, having a larger axial extent than the slot, is milled into the turbine rotor above the slot. The milling typically removes the slot's retaining member and provides a location where the weight can be circumferentially introduced into the slot. One challenge with balance weight entry ports is that initially milling the slot's retaining member to form the entry port can leave a circumferentially extending portion (peak) of the retaining member and potentially leave a sharp corner at the bottom of the port's sidewall. Each of these structures can lead to the initiation of damage, such as cracks, in the turbine rotor. The damage can be very difficult to repair without otherwise damaging the turbine rotor. Summary of the Invention

[0003] A first aspect of the present disclosure provides a turbine rotor comprising: a rotor body; a balance weight slot defined in an outer periphery of the rotor body, the balance weight slot having a first axial width and a first radially outer surface that is a first radial distance from an axis of the rotor body; and a balance weight entry port defined in a portion of the outer periphery of the rotor body and aligned with the balance weight slot, the balance weight entry port having a second axial width greater than the first axial width and a second radially outer surface that is a second radial distance from the axis of the rotor body less than the first radial distance.

[0004] A second aspect of the present disclosure provides a tool for forming a balance weight entry port for a balance weight slot in a rotor body of a turbine rotor, the tool including: an electric machining head; a clamping system configured to couple the electric machining head to at least a portion of a merge joint flange of the rotor body; a head circumferential positioning system configured to position the electric machining head at a selected one of a plurality of circumferential positions relative to the balance weight slot on the rotor body; and a head radial positioning system configured to move the electric machining head radially relative to the balance weight slot on the rotor body at each of the plurality of circumferential positions to modify the balance weight slot for machining the rotor body.

[0005] A third aspect of the present disclosure provides a method for providing a balance weight entry port for a balance weight slot defined in a rotor body of a turbine rotor and extending circumferentially about the rotor body, the method comprising performing a first plunge machining operation partially radially within the rotor body to modify the balance weight slot at a first circumferential location, and one of: a) performing a circumferential translation after the first plunge machining operation; and b) performing a second plunge machining operation partially radially within the rotor body to modify the balance weight slot at a second circumferential location different from the first circumferential location. performing a second plunge machining operation, the opening created by the second plunge machining operation being coextensive with the opening created by the first plunge machining operation; and performing a third plunge machining operation partially radially within the rotor body to modify a balance weight slot at a third circumferential location different from the first and second circumferential locations, the opening created by the third plunge machining operation being coextensive with the first and second plunge machining operations, each plunge machining and circumferential translation removing a portion of the rotor body within or adjacent to the balance weight slot.

[0006] The exemplary aspects of the present disclosure are designed to solve the problems described herein and / or other problems not discussed.

[0007] These and other features of the present disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure, taken in conjunction with the accompanying drawings which illustrate various embodiments of the present disclosure. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an exemplary gas turbine system. [Figure 2] 1 is a side perspective view of a turbine rotor according to the prior art; [Figure 3]FIG. 1 is an enlarged perspective view of a balance weight entry port and balance weight slot according to the prior art. [Figure 4] 10A-10C are cross-sectional views of an exemplary configuration of a balance weight within a balance weight slot. [Figure 5] FIG. 10 is a front perspective view of a tool positioned on a rotor body to form a balance weight entry port according to an embodiment of the present disclosure. [Figure 6] FIG. 10 is a front perspective view of a tool for forming a balance weight entry port according to an embodiment of the present disclosure. [Figure 7] FIG. 10 is a rear perspective view of a tool for forming a balance weight entry port according to an embodiment of the present disclosure. [Figure 8] FIG. 10 is a top view of a member of a head circumferential positioning system according to an embodiment of the present disclosure. [Figure 9] FIG. 10 is a cross-sectional view of a machining head for machining a balance weight entry port according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic top view of a rotor body and balance weight slots with machining steps indicated by circles representing machining heads according to an embodiment of the present disclosure. [Figure 11] 10 is a schematic cross-sectional view of machining a balance weight slot to form a balance weight entry port according to an embodiment of the present disclosure. FIG. [Figure 12] FIG. 10 is a top view of a balance weight entry port according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] It should be noted that the drawings of the present disclosure are not necessarily to scale. The drawings are intended to illustrate only typical aspects of the present disclosure and therefore should not be considered limiting of the scope of the present disclosure. In the drawings, like numbers represent like elements between the drawings.

[0010] As an initial matter, in order to clearly explain the subject matter of this disclosure, it is necessary to select specific terminology when referring to and describing relevant machine components within turbomachinery. Wherever possible, common industry terminology is used and utilized consistent with its accepted meaning. Unless otherwise noted, such terminology should be given a broad interpretation consistent with the context of this application and the scope of the appended claims. Those skilled in the art will recognize that in many cases, a particular component may be referred to using several different or overlapping terms. Content described herein as being a single component may include multiple components and may be referred to as consisting of multiple components in other contexts. Alternatively, content described herein as including multiple components may be referred to as a single component elsewhere.

[0011] Additionally, several descriptive terms may be used frequently herein, and it will prove useful to define these terms at the beginning of this section. These terms and their definitions are as follows, unless otherwise specified: As used herein, "downstream" and "upstream" are terms that indicate a direction relative to the flow of a working fluid through a turbine engine, or a fluid such as, for example, the flow of air through a combustor or a coolant through one of the turbine's component systems. The term "downstream" corresponds to the direction of fluid flow, and the term "upstream" refers to the direction opposite to the flow (i.e., the direction from which the fluid is coming). The terms "forward" and "aft," unless otherwise specified, refer to directions, with "forward" referring to the front or compressor end of the engine and "aft" referring to the aft portion of the turbomachine.

[0012] It is often necessary to describe components located at various radial positions relative to a central axis. The term "radial" refers to movement or position perpendicular to an axis. For example, if a first component is located closer to an axis than a second component, the first component may be described herein as being "radially inward" or "inward" of the second component. Conversely, if a first component is located farther from the axis than the second component, the first component may be described herein as being "radially outward" or "outward" of the second component. The term "axial" refers to movement or position parallel to an axis, e.g., the axis of a turbine rotor. Finally, the term "circumferential" refers to movement or position around an axis. It will be understood that such terms may be applied in relation to the central axis of the turbine.

[0013] In addition, as explained below, certain descriptive terms may be used frequently in this specification: the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another, and are not intended to denote the location or importance of the individual components.

[0014] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural unless expressly stated otherwise. It will be further understood that the terms "comprise" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Optional" or "optionally" means that the event or circumstance described following the term may or may not occur, and that the component or element described following the term may or may not be present, and that the description includes cases where such an event occurs or where such element is present, as well as cases where such event does not occur or where such element is absent.

[0015] When an element or layer is referred to as being "on," "engaged," "connected," or "coupled" to another element or layer, it may be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers may be present. Conversely, when an element is referred to as being "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there may not be intervening elements or layers. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0016] FIG. 1 is a schematic diagram of an exemplary turbomachine that may utilize a turbine rotor 110 according to an embodiment of the present disclosure. Here, the turbomachine includes a gas turbine (GT) system 100. The GT system 100 includes a compressor 102 and a combustor 104. The combustor 104 includes a combustion zone 105 and a fuel nozzle assembly 106. The GT system 100 also includes a turbine 108 and a common turbine rotor 110. During operation, air flows through the compressor 102, and compressed air is supplied to the combustor 104. Specifically, the compressed air is supplied to a fuel nozzle assembly 106 integrated with the combustor 104. The assembly 106 is in flow communication with the combustion zone 105. The fuel nozzle assembly 106 is also in flow communication with a fuel source (not shown in FIG. 1 ) and directs fuel and air to the combustion zone 105. The combustor 104 ignites and combusts the fuel. The combustor 104 is in flow communication with a turbine 108, where thermal energy of the gas stream is converted to mechanical rotational energy. The turbine 108 includes multiple stages of rotatable blades coupled to and rotatingly driving a turbine rotor 110. The compressor 102 is also rotatably coupled to the turbine rotor 110. The present disclosure is not limited to any particular GT system and may be used in connection with any GT system, such as, for example, any of the HA, F, B, LM, GT, TM, and E-class engine models from General Electric Company (Greenville, South Carolina), as well as engine models from other manufacturers. Furthermore, the teachings of the present disclosure are not limited to turbomachinery in the form of a gas turbine system, but may be applied to any rotating element or rotor that includes balance slots and requires balancing.

[0017] FIG. 2 shows a side view of a turbine rotor 110 with any turbine blades / stages removed. The turbine rotor 110 may include a rotor body 112 in the form of a generally cylindrical shaft, which may have several blade stages 114 ( FIG. 1 only) (for the compressor 102 and / or turbine 108) coupled thereto. The turbine rotor 110 may exhibit an asymmetry, or imbalance, in its mass distribution. The imbalance may cause periodic forces and torques, such as vertical and lateral vibrations, on the turbine rotor 110, which may also cause the rotor to vibrate during use, similar to an unbalanced tire on an automobile. To address this situation, as shown in FIGS. 2 and 3 (enlarged perspective views), one or more balance weights 120 may be coupled to one or more circumferential positions within circumferentially extending balance weight slots 122 (two shown in FIG. 2 ) within the rotor body 112 of the turbine rotor 110 to balance the rotor and allow it to rotate without vibration. As shown in the example cross-sectional view of FIG. 4, the balance weight slot 122 and the balance weight 120 are complementary configured to retain the balance weight within the slot. For example, the balance weight slot 122 and the balance weight 120 can have complementary cross-sectional shapes configured to retain the balance weight 120 therein. In one non-limiting example shown in FIG. 4, the balance weight 120 and the balance weight slot 122 have complementary trapezoidal cross-sectional shapes. Here, the balance weight slot 122 includes opposing retaining members 124 in the form of ears or tabs. A fastener 125, such as a set screw, can be used to lock the balance weight 120 in place.

[0018] To introduce the balance weight 120 into the balance weight slot 122, the rotor body 112 includes one or more balance weight entry ports 126. Each balance weight entry port 126 comprises an axially enlarged area of ​​the balance weight slot 122 through which the balance weight 120 can be positioned and circumferentially slid within the slot. As shown in the enlarged perspective view of FIG. 3 , the balance weight entry ports 126 can be formed, for example, by machining the retaining member 124 out of the slot 122 to create the port 126 but leaving a peak 128. During use, peaks and / or sharp corners 130 where the vertical sidewall 132 of the port 126 meets the radially outer surface 134 of the slot 122 (sharp corners with a radius of less than 0.76 mm) can crack. The cracks can propagate within the rotor body 112. Therefore, peaks and sharp corners should be avoided during initial manufacturing and may have to be removed during inspection.

[0019] As described above, the present disclosure provides a turbine rotor including a rotor body and a balance weight slot defined in the outer periphery of the body. The balance weight slot has a first axial width and a first radially outer surface that is a first radial distance from the axis of the rotor. The rotor also includes a balance weight entry port defined in a portion of the outer periphery of the rotor body and substantially aligned with the balance weight slot. The balance weight entry port has a second axial width greater than the first axial width. The balance weight slot also has a second radially outer surface that is a second radial distance from the axis of the rotor body less than the first radial distance, meaning that the entry port extends further into the rotor body than the slot. Embodiments of the present disclosure also include methods and tools for forming entry ports in a rotor body. The tool can be used to perform a series of plunge machining steps to create the new balance weight entry port. This method can be applied to new or used rotors to remove peaks 128 (FIG. 3) and / or sharp corners 130 (FIG. 3) originating from previously formed entry ports that may contain cracks or other damage. New balance weight entry ports have rounded corners to prevent new cracks.

[0020] Referring to Figures 5-12, a method and tool for performing the method according to an embodiment of the present disclosure are described. Figures 5 and 6 show front perspective views of a tool 140 for forming balance weight entry ports 142 for balance weight slots 122 in a rotor body 112 of a turbine rotor 110. Figure 5 shows the tool 140 in place on the rotor body 112, and Figure 6 shows the tool 140 spaced apart from the rotor body 112. The tool 140 includes a powered machining head 150. The powered machining head 150 can include any known or later-developed rotary actuator 152, such as an electric motor, pneumatic motor, or hydraulic motor, capable of rotating a machining element 154. In certain embodiments, the powered machining head 150 also enables a single plunge machining operation with a controlled and limited amount of circumferential translation, thereby reducing the number of required plunge machining steps. The machining element 154 will now be described. The tool 140 also includes a clamping system 156 configured to couple the powered machining head 150 to at least a portion of a merge joint flange 160 of the rotor body 112. As shown, the merge joint flange 160 may include radially extending merge joint flanges 162, 164 axially coupled to two axially coupled portions 166, 168 of the rotor body 112. However, the clamping system 156 may couple to one or both flanges 162, 164, depending on the configuration of the rotor body 112. For example, if the rotor body 112 is separated into portions 166, 168, the clamping system 156 may couple to only one of the flanges 162, 164. The clamping system 156 may include any known or later-developed system for temporarily securing the powered machining head 150 to the rotor body 112. In the illustrated non-limiting example, the clamping system 156 includes a first clamping member 170 movably coupled to a second clamping member 172, optionally having one or more guide rails 174 that direct axial movement of the members.The clamping system 156 may also include an actuator 176, such as a manual crank or an electric actuator (as shown), for axially moving the clamping members 170, 172 toward or away from one another. The actuator 176 may include, for example, a motorized worm gear 177 that is threadably coupled to the members 170, 172 and that can be rotated to change the axial position of the members. A wide variety of alternative actuators 176, such as a linear ram, may also be utilized. The actuator 176 may be operated to have the clamping members 170, 172 clamp the powered machining head 150 in place on one or both flanges 162, 164 of the merge joint flange 160 for machining the rotor body 112, and may similarly be operated to release the powered machining head 150 from the rotor body 112. The clamping members 170, 172 may include any structure to assist in gripping the merge joint flanges 162, 164, such as roughened surfaces, locking mechanisms, etc.

[0021] Tool 140 may also optionally include at least one tie-down member 180 having a first end 182 configured to fit into balance weight slot 122 and a second end 184 coupled to clamping system 156. Similar to balance weight 120 ( FIG. 4 ), first end 182 can have any shape configured to be positioned and retained within slot 122, e.g., a trapezoidal shape for a trapezoidal slot. For example, first end 182 may be sized and shaped to fit into slot 122, rotate to be retained therein, or be sized and shaped to fit into slot 122 using balance weight entry port 126 ( FIG. 3 ). Second end 184 may include any mechanism for coupling to clamping system 156. As shown, second end 184 may include an adjuster 186 for adjusting the radial position of first end 182, although adjuster 186 is not required. The adjuster 186 may include any known or later developed mechanism, such as a threaded end and fastener, clamp, for linearly varying the position of the first end 182 relative to the clamping system 156. One or more tie-downs 180 may be utilized.

[0022] FIG. 7 illustrates a rear perspective view of a particular embodiment of tool 140. As best shown in FIG. 7 , tool 140 also includes a head circumferential positioning system 190 configured to position powered machining head 150 at one of the circumferential positions relative to balance weight slot 122 of rotor body 112 and to translate powered machining head 150 circumferentially relative to balance weight slot 122 of rotor body 112. Head circumferential positioning system 190 can take any form of structure capable of adjusting the circumferential position of powered machining head 150, such as, for example, a linear actuator, a mechanical adjustment system, etc. In one example illustrated in FIG. 7 , positioning system 190 can include a first member 192 fixedly coupled to powered machining head 150, e.g., a portion of the head, and a second member 194 fixedly coupled to clamping system 156. As shown, second member 194 can be part of clamping system 156, e.g., clamping member 172, or can be a separate element coupled to clamping system 156. 8 shows a top view of the second member 194. The first member 192 and the second member 194 are slidably coupled. In one non-limiting example, the first member 192 may include a protrusion 196 that slidably rides in a slot 198 in the second member 194. Other arrangements may be possible, such as, for example, a guide rail.

[0023] As best shown in FIG. 8 , the second member 194 may include a position selection member 200A-C for each of a plurality of circumferential positions. The number of possible circumferential positions provided relative to the balance weight slots 122 of the rotor body 112 may be user-definable depending on the desired circumferential extent of the balance weight entry ports 142. However, in certain embodiments, at least three positions are possible. The first member 192 may also include a position selector 202 configured to selectively position a selected one of the position selection members 200A-C of the second member 194 to position the powered machining head 150 at a selected one of the plurality of circumferential positions relative to the balance weight slots 122 of the rotor body 112. In one non-limiting example, the position selector 202 may include a pin 204 extending through the first member 192 and seatable in one of the position selection members 200A-C. The position selection members 200A-C may include openings in the second member 194 and may be spaced to create a desired circumferential position of the head. As will be described further, the position selection members 200A-C may be spaced any distance necessary to ensure that the new entry port 142 circumferentially clears the original entry port using the position selection members. In an alternative embodiment, the position selector 202 may be omitted, and the powered machining head 150 may be capable of a single plunge machining operation with a controlled and limited amount of circumferential translation defined by the length of the slot 198, thus reducing the number of required plunge machining steps. Here, the machining element 154 may be plunged once and then translated circumferentially as the protrusion 196 of the first member 192 slidably rides in the slot 198 of the second member 194, providing limited and controlled circumferential movement of the machining element 154 to create the entry port 142.

[0024] 5 and 6, the tool 140 also includes a head radial positioning system 210 configured to move the powered machining head 150 radially (vertically as shown on the page) relative to the balance weight slot 122 on the rotor body 112. The radial movement can be performed at each of a plurality of circumferential positions to machine the rotor body 112, modify the balance weight slot 122 (FIG. 3), and create the balance weight entry port 142. The head radial positioning system 210 can include any form of linear actuator 212, such as a manual crank, electric, pneumatic, or hydraulic ram. The head radial positioning system 210 is secured to a clamping system 156.

[0025] The machining element 154 is configured to form the balance weight entry port 142 in the rotor body 112 relative to the balance weight slot 122. The machining element 154 can be used to form the balance weight entry port 142 in the slot during manufacturing of the rotor body 112. Alternatively, the machining element 154 can be used to replace or repair a previously formed balance weight entry port 126 ( FIG. 3 ). In the latter case, the machining element 154 is larger in size than the previously formed balance weight entry port 126 ( FIG. 3 ) to remove additional axial portions of the rotor body 112 and to remove damage, such as cracks or other damage, in the peaks 128 or sharp corners 130. The machining element 154 can include any form of rotary machining element capable of forming the structures described herein. In non-limiting examples, the machining element 154 can include a cutting head, a drill bit, a grinding head, or the like. FIG. 9 illustrates a cross-sectional view of an exemplary machining element 154 according to an embodiment of the present disclosure. The machined element 154 may have a circular cross-section (see, e.g., FIG. 5 ) with a rounded corner 220 between a radial sidewall 222 and a machined surface 223. The rounded corner 220 is configured for the balance weight entry port 142, i.e., to form a rounded corner 236 ( FIG. 11 ) (fillet) between the radially outer surface 232 ( FIG. 11 ) and its sidewall 228 ( FIG. 11 ). The radius may be user-defined to remove damage, such as existing cracks, and / or to prevent further cracking. In certain exemplary embodiments, the rounded corner 220 may have a radius R ranging from 1.250 millimeters (mm) to 5.080 mm. Other ranges may be possible, depending, for example, on the size of the rotor body 112 and the slot 122.

[0026] In accordance with embodiments of the disclosed method, a tool 140 can be used to form a balance weight entry port 142 for a balance weight slot 122 defined in a rotor body 112 of a turbine rotor 110. FIG. 10 shows a schematic top view of the rotor body 112 and slot 122, with the machining steps illustrated by circles representing machining elements 154. FIG. 11 shows a schematic cross-section of the machining of a balance weight slot 122 according to various embodiments. For reference purposes, FIG. 11 shows the remaining circumferential surface of the retaining member 124 of the slot 122. As will be appreciated, the machining element 154 can be used to create a balance weight entry port 142 according to embodiments of the disclosed method by removing the retaining member 124 of the slot 122 at any desired circumferential location (on or off-page), among other structures. FIG. 11 also shows in dashed lines an existing balance weight entry port 226, including a sidewall 132 that meets the first radially outer surface 134 of the balance weight slot 122 at a sharp corner 130. As described below, tool 140 can be used to enlarge existing balance weight entry port 126 to create new entry port 142. In one non-limiting example, new entry port 142 may be 0.050 mm to 2.540 mm larger on each side, although other ranges may be possible depending on the size of rotor body 112 and / or slot 122.

[0027] In operation, the tool 140 is positioned at a desired circumferential location on the rotor body 112 to create the balance weight entry port 142 by clamping to one or more flanges 162, 164, i.e., for a new port or to replace an existing port 126 ( FIG. 3 ). The head circumferential positioning system 190 is set to a first circumferential position, such as 200A, as described. The head radial positioning system 210 is used to perform several plunge machining operations to create the balance weight entry port 142. Each machining operation uses a circular machining element 154. For purposes of illustration, and as noted above, the described embodiment uses three circumferentially spaced locations 200A-C to perform three machining steps PM1-PM3 ( FIG. 10 ) to create the entry port 142, although more or less than three steps may be used. (Note that the second plunge machining PM2 is shown in dashed lines in FIG. 10 to distinguish it from the other machining operations PM1, PM3.) As shown in FIGS. 5 and 10 , the tool 140 can be coupled to one or more flanges 162, 164 such that each machining element 154 is axially positioned relative to the rotor body 112 (e.g., by a clamping system 156) within a range of 0 millimeters (mm) to 0.762 mm from the center (CL) of the balance weight slot 122. Note that other ranges may be possible depending on the size of the rotor body 112 and / or slot 122.

[0028] As shown in FIG. 10 , a first plunge machining PM1 is performed radially partially into the rotor body 112 to modify the balance weight slot 122 at a first circumferential location 200A using the head radial positioning system 210. The head circumferential positioning system 190 is set to a second circumferential location, e.g., 200B, by the position selector 202 ( FIG. 7 ). A second plunge machining PM2 is performed radially partially into the rotor body 112 to again modify the balance weight slot 122 at a second circumferential location 200B using the head radial positioning system 210. As described above, the second circumferential location 200B is different from the first circumferential location 200A. The opening 230 created by the second plunge machining PM2 is coextensive with the opening 232 formed by the first plunge machining PM1. Next, the head circumferential positioning system 190 is set to a third circumferential position, e.g., 200C, by the position selector 202 (FIG. 7). The head radial positioning system 210 is used to perform a third plunge machining PM3 partially radially into the rotor body 112 to again modify the balance weight slot 122 at the third circumferential position 200C. As described above, the third circumferential position 200C is different from the first and second circumferential positions 200A, 200B. The opening 234 formed by the third plunge machining PM3 is coextensive with the openings 230, 232 formed by the first plunge machining PM1 and the second plunge machining PM2. Each machining, i.e., each circumferential location 200A-C, can be circumferentially spaced any desired and / or necessary distance from the center of the adjacent machining to collectively create an entry port 142 having a desired circumferential extent, e.g., completely removing the circumferential extent of the original entry port. As shown, each plunge machining PM1-PM3 removes a portion of the rotor body 112 within or adjacent to the balance weight slot 122, e.g., the retaining member 124 and a portion of the sidewall 229 of the slot and / or previous slot 122.As mentioned above, in other embodiments, the powered machining head 150 is capable of single plunge machining with a controlled and limited amount of circumferential translation, thus reducing the number of plunge machining steps required. In this case, the single plunge machining can be completed using circumferential translation of the machining element 154 to create the enlarged circumferential entry port 142. Here, the position selector 202 may be omitted, as discussed above. In either case, once completed, any tie-downs 180 can be loosened and removed, the clamping system 156 can be loosened, and the tool 140 can be removed from the flanges 162, 164.

[0029] When used to repair an existing balance weight entry port 126 ( FIGS. 3 and 11 ), the method may include attaching the tool 140 to at least a portion of a merge joint flange 160, i.e., one or both of flanges 162, 164, of a used rotor body 112 that includes the existing (first) balance weight entry port 126 ( FIGS. 3 and 11 ) for the balance weight slot 122, using a clamping system 156. Advantageously, the tool 140 can be used anywhere in the field, even with the turbine rotor 110 in place in a power plant from which the casing has been removed. The method may include performing one or more plunge machining operations, e.g., first, second, and third plunge machining operations PM1-PM3, to modify the rotor body 112 to create a new (second) balance weight entry port 142 for the balance weight slot 122 at the same circumferential location as the existing balance weight entry port 126. Here, the existing balance weight entry port 126 has a first axial width W1 (FIG. 11), and the new balance weight entry port 142 has a second axial width W2 that is greater than the first axial width W1. That is, the processing element 154 is wider than the first axial width W1. The second axial width W2 can be defined by the new sidewall 228 of the new entry port 142.

[0030] The plunge machining, whether for a new or used rotor body 112, also extends beyond the first radially outer surface 134 into the balance weight slot 122 to create a new radially outer surface 232. As a result, as shown in FIG. 11 , the balance weight slot 122 has a first radially outer surface 134 that is a first radial distance RD1 from the axis A of the rotor body 112 (see also FIG. 1 ) and an entry port 142 with a second radially outer surface 238 that is a second radial distance RD2 from the axis A of the rotor body 112 that is less than the first radial distance RD1. For repair purposes, the deeper radially outer surface 232 ensures complete removal of damage, such as cracks. The difference between the first radial distance RD1 from the axis A of the rotor body 112 and the second radial distance RD2 from the axis A of the rotor body 112 can be in the range of 0.254 millimeters (mm) to 2.286 mm, although the range may vary depending, for example, on the amount of damage to be removed in the existing entry port 126. Note that the balance weight slot 122 includes a sidewall 229 (formed by the retaining member 124) that extends from the slot (first) radially outer surface 134 at a possibly non-perpendicular angle α, and the new balance weight entry port 142 has a sidewall 228 that extends from the new (second) radially outer surface 232 at a perpendicular angle β. However, the machining element 154 creates a rounded corner 236 joining the new radially outer surface 232 and the sidewall 228 of the new balance weight entry port 142. That is, the machining removes sharp corners 130 and sidewalls 132 of the existing balance weight entry port 126, as well as any existing peaks 128 ( FIG. 3 ), which may contain cracks or other damage. The sidewalls 228 are increased in axial dimension by the machining elements 154. Each sidewall 228 may be increased axially by 25.4 millimeters (mm), although other ranges may be possible depending on the size of the rotor body 112 and slots 122.Thus, balance weight entry port 142 provides space for balance weight 120 (FIG. 4) to be introduced into balance weight slot 122 in the same manner as original entry port 126, but provides rounded corners 236 that act to reduce cracking of rotor body 112 during subsequent use. Rounded corners 236 may have a radius ranging from 1.250 millimeters (mm) to 5.080 mm, for example.

[0031] 10-12, a turbine rotor 240 according to an embodiment of the present disclosure may include a rotor body 112 and a balance weight slot 122 defined in an outer periphery 244 of the rotor body 112. As shown in FIG. 11, the balance weight slot 122 has an axial width W3 and a first radially outer surface 134 that is a first radial distance RD1 from the axis A of the rotor body 112. The rotor body 112 may include a first merge joint flange 162 and a second merge joint flange 164 axially coupled to the first merge joint flange 162 at a rotor flange interface 250 (FIG. 10). The balance weight slot 122 may be axially adjacent to the rotor flange interface 250, although other locations are possible.

[0032] The turbine rotor 240 also includes a balance weight entry port 142 defined in a portion of the outer periphery 244 of the rotor body 112 and aligned with the balance weight slot 122. The balance weight entry port 142 has an axial width W2 that is greater than the axial width W3 of the slot 122, thereby allowing the balance weight 120 (FIG. 4) to be introduced into the slot at the entry port. The balance weight entry port 142 also includes a radially outer surface 134 (FIG. 11) at a radial distance RD2 from the axis A of the rotor body 112 that is less than the radial distance RD1 of the radially outer surface 232 of the slot 122. The difference between the radial distance RD1 of the slot from the axis A of the rotor body 112 and the radial distance RD2 of the entry port 142 from the axis A of the rotor body 112 may be within a range of 0.254 millimeters (mm) to 2.286 mm.

[0033] As shown in the top view of FIG. 12 , the balance weight entry port 142 includes an interface 252 between the radially outer surface 134 of the slot 122 and the radially outer surface 232 of the port 142. The interface 252 is rounded, i.e., has the same radius as the rounded corners 236 due to the rounded corners 220 of the machined elements 154 ( FIG. 9 ). The balance weight slot 122 has a first cross-sectional shape, e.g., a trapezoid, and the balance weight entry port 142 has a cross-sectional shape that is different from the slot's first cross-sectional shape, e.g., a rectangle with rounded corners 236. The balance weight slot 122 includes a sidewall 229 ( FIG. 11 ) that may extend at a non-perpendicular angle α from the slot's radially outer surface 134. In contrast, the balance weight entry port 142 has a sidewall 228 that extends at a perpendicular angle β from the port's radially outer surface 232. As mentioned above, the entry port 142 includes a rounded corner 236 that joins the balance weight entry port second radially outer surface 232 and the sidewall 228. The rounded corner 236 may have a radius ranging from 1.250 millimeters (mm) to 5.080 mm, although other ranges may be possible depending on the size of the rotor body 112 and / or slot 122.

[0034] Embodiments of the present disclosure provide turbine rotors with entry ports that have rounded corners to prevent damage such as cracks. The entry ports also extend farther into the rotor body to reduce damage. Methods and tools according to embodiments of the present disclosure enable entry ports to be formed in new or used rotor bodies. When applied to used rotor bodies, forming new entry ports can remove damage from the rotor body. The tools and methods can be advantageously used at the manufacturing site or in the field.

[0035] The above description and figures illustrate some of the processes involved according to some embodiments of the present disclosure. It should be noted that in some alternative implementations, the acts or words described in the figures may occur out of the order mentioned, or may actually be performed substantially simultaneously or in reverse order, depending, for example, on the acts involved. Also, those skilled in the art will recognize that additional steps, such as machining or finishing steps, may be added.

[0036] As used herein throughout this specification and claims, approximation may be applied to modify any quantitative expression that can reasonably be varied without resulting in a change in the basic function to which it pertains. Thus, values ​​modified by terms such as "about," "approximately," and "substantially" are not limited to the exact value specified. In at least some instances, approximation may correspond to the precision of the measuring instrument used to measure the value. Here, and throughout this specification and claims, range limitations are combinable and / or interchangeable, and unless the context and language dictate otherwise, such ranges are identified and include all subranges encompassed therein. "About," as applied to a particular value in a range, applies to both endpoints and may indicate + / - 10% of the stated value, unless specifically dependent on the precision of the measuring instrument used to measure the value.

[0037] The corresponding structure, material, acts, and equivalents of all means-plus-function or step-plus-function elements in the following claims are intended to encompass any structure, material, or acts for performing that function in combination with the elements in other specifically claimed claims. The description of the present disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The present embodiments were chosen and described in order to best explain the principles and practical application of the disclosure and to enable others skilled in the art to understand the disclosure in its various embodiments with various modifications as suited to the particular uses envisioned. [Explanation of symbols]

[0038] 100 Gas Turbine (GT) System 102 Compressor 104 Combustor 105 Combustion Zone 106 Fuel nozzle assembly 108 Turbine 110 Common turbine rotor 112 rotor body 114 Blade Stage 120 balance weight 122 Balance weight slot 124 Retaining member 125 Fasteners 126 Balance weight entry port 128 Peak 130 Sharp Corners 132 Side wall 134 Radial outer surface 140 Tools 142 Balance weight entry port, circumferential entry port 150 Electric Machining Head 152 Rotary Actuator 154 Machining Elements 156 Clamping System 160 merge joint flange 162 Merge joint flange 164 Merge joint flange 166 parts 168 parts 170 first clamp member 172 second clamping member 174 Guide Rail 176 Actuator 177 Electric Worm Gear 180 Tie-down member 182 first end 184 Second End 186 Adjuster 190 Head Circumferential Positioning System 192 First Component 194 Second Component 196 Protrusion 198 Slots 200A Position selection member, first circumferential position 200B Position selection member, second circumferential position 200C Position selection member, third circumferential position 202 Position Selector 204 pins 210 Head Radial Positioning System 212 Linear Actuator 220 rounded corners 222 Radial sidewall 223 Machined surface 226 Balance weight entry port 228 Side wall 229 Side wall 230 Opening 232 Opening, radially outer surface 234 Opening 236 Rounded Corners 238 Radial outer surface 240 Turbine rotor 244 perimeter 250 rotor flange interface 252 Interface A axis PM1 Plunge Machining PM2 Plunge Machining PM3 Plunge Machining R radius RD1 First radial distance RD2 Second radial distance W1 First axial width W2 Second axial width W3 Axial width α non-vertical angle β vertical angle

Claims

1. a rotor body (112); a balance weight slot (122) defined in an outer periphery (244) of the rotor body (112), the balance weight slot (122) having a first axial width (W1) and a radially outer surface (134) at a first radial distance (RD1) from an axis (A) of the rotor body (112); a balance weight entry port (142) defined in a portion of the outer periphery (244) of the rotor body (112) and aligned with the balance weight slot (122), the balance weight entry port (142) having a second axial width (W2) greater than the first axial width (W1) and a second radially outer surface (238) at a second radial distance (RD2) from the axis (A) of the rotor body (112) less than the first radial distance (RD1); A turbine rotor (110) comprising:

2. 2. The turbine rotor of claim 1, wherein the rotor body includes a first merge joint flange and a second merge joint flange axially coupled to the first merge joint flange at a rotor flange interface, and the balance weight slot is axially adjacent the rotor flange interface.

3. 2. The turbine rotor of claim 1, wherein the balance weight entry port includes an interface between the first radially outer surface and the second radially outer surface, the interface being rounded.

4. 2. The turbine rotor of claim 1, wherein the balance weight slot has a first cross-sectional shape and the balance weight entry port has a second cross-sectional shape that is different from the first cross-sectional shape.

5. 2. The turbine rotor of claim 1, wherein the balance weight slot includes a sidewall that extends at a non-perpendicular angle from the first radially outer surface, and the balance weight entry port has a sidewall that extends at a perpendicular angle from the second radially outer surface, and further comprises a rounded corner joining the second radially outer surface and the sidewall of the balance weight entry port.

6. The turbine rotor (110) of claim 5, wherein the rounded corners (236) have a radius in the range of 1.250 millimeters (mm) to 5.080 mm.

7. 2. The turbine rotor of claim 1, wherein a difference between the first radial distance from the axis of the rotor body and the second radial distance from the axis of the rotor body is in a range of 0.254 millimeters (mm) to 2.286 mm.

8. 1. A tool (140) for forming a balance weight entry port (142) for a balance weight slot (122) in a rotor body (112) of a turbine rotor (110), comprising: a powered machining head (150); a clamping system (156) configured to couple the powered machining head (150) to at least a portion of a merge joint flange (160) of the rotor body (112); a head circumferential positioning system (190) configured to position the powered machining head (150) at a selected one of a plurality of circumferential positions (200A-C) relative to the balance weight slot (122) of the rotor body (112); a head radial positioning system (210) configured to radially move the powered machining head (150) relative to the balance weight slot (122) on the rotor body (112) at each of the plurality of circumferential positions (200A-C) to machine the rotor body (112) to modify the balance weight slot (122); A tool (140) comprising:

9. The tool (140) of claim 8, wherein the plurality of circumferential positions (200A-C) relative to the balance weight slot (122) of the rotor body (112) includes at least three positions.

10. The head circumferential positioning system (190) a first member (192) fixedly coupled to the powered machining head (150); a second member (194) fixedly coupled to the clamping system (156), the second member (194) including a position selection member (200A-C) for each of the plurality of circumferential positions (200A-C), the second member (194) being slidably coupled to the first member (192); Including, the first member (192) includes a position selector (202) configured to position the first member (192) relative to the second member (194) at a selected one of the position selection members (200A-C) of the second member (194) to position the electric machining head (150) at the selected one of the plurality of circumferential positions (200A-C) relative to the balance weight slot (122) of the rotor body (112); The tool (140) of claim 8.

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