Patent Publication Number: US-2016237825-A1

Title: Balanced rotating component for a gas powered engine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 61/882,691 filed Sep. 26, 2013. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with government support under Contract No. FA8650-09-D-2923 awarded by the United States Air Force. The Government has certain rights in this invention. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to rotating components in a turbine engine, and more specifically to a balanced rotating component for the same. 
     BACKGROUND OF THE INVENTION 
     Gas powered turbines, such as the gas powered turbine engines used to generate thrust for an aircraft, typically include a fan, compressor, combustor, and turbine arranged to generate thrust in a known manner. Within the compressor and the turbine are multiple rotating components such as compressor rotors and turbine rotors. Due to variances in the engine designs, the need to accommodate non-rotating components within the gas powered turbine engine, and manufacturing variances from engine to engine, stock rotating components are often not circumferentially balanced. 
     Circumferential imbalance in the rotating components introduces inefficiencies in the gas powered turbine and wear on the rotating component and/or the joint between the rotating component and the shaft in the gas powered turbine to which the rotating component is attached. The additional wear and stress resulting from the circumferential imbalance reduces the expected lifetime of the rotating component and potentially reduces the expected lifetime of the engine itself. 
     SUMMARY OF THE INVENTION 
     A rotating component for a turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes a rotor portion protruding radially outward, at least one overweight region is located in the rotor portion, and at least one additively manufactured counterweight region positioned relative to the at least one overweight region such that the rotating component is circumferentially balanced. 
     A further embodiment of the foregoing rotating component includes a retaining ring for connecting a rotor coverplate to said rotating component, wherein the at least one additively manufactured counterweight region is a region of said retaining ring. 
     In a further embodiment of the foregoing rotating component, the counterweight region is a distinct component from the rotor portion and the retaining ring, and the at least one counterweight region is connected to the rotor portion and the retaining ring such that the counterweight region is static relative to the rotor portion. 
     In a further embodiment of the foregoing rotating component, the at least one counterweight region is integral to the retaining ring. 
     In a further embodiment of the foregoing rotating component, the retaining ring is entirely additively manufactured. 
     In a further embodiment of the foregoing rotating component, the additively manufactured counterweight region is a portion of and the retaining ring, is less than 100% of the retaining ring, and is additively manufactured after a remainder of the rotating component is manufactured. 
     In a further embodiment of the foregoing rotating component, the rotating component is characterized by a lack of a balance ring. 
     In a further embodiment of the foregoing rotating component, the additively manufactured counterweight region portion includes at least a first material and a second material, and the second material is denser than the first material. 
     In a further embodiment of the foregoing rotating component, a circumferential weight profile of the rotating component is at least partially determined by a ratio of the amount of the second material used to the remainder of the material used. 
     In a further embodiment of the foregoing rotating component, the part has a predetermined dimensional profile regardless of the circumferential weight profile of the rotating component. 
     A method for creating a rotating component for a turbine according to an exemplary embodiment of this disclosure, among other possible things includes manufacturing at least a first portion of the rotating component, testing the at least a first portion of the rotating component to determine any circumferential imbalance, and additively manufacturing at least second portion of the rotating component including a counterweight region in the second portion of the rotating component, thereby circumferentially balancing the rotating component. 
     In a further embodiment of the foregoing method, the step of additively manufacturing at least second portion of the rotating component including a counterweight region in the second portion of the rotating component, thereby circumferentially balancing the rotating component further includes additively manufacturing a second portion of the rotating component integral to the first portion of the rotating component. 
     In a further embodiment of the foregoing method, the second portion of the rotating component is fixedly attached to the first portion of the rotating component and is a distinct component from a remainder of the rotating component. 
     In a further embodiment of the foregoing method, the step of additively manufacturing at least second portion of the rotating component including a counterweight region in the second portion of the rotating component, thereby circumferentially balancing the rotating component, further includes additively manufacturing the counterweight region of the second portion at least partial is of a first material and additively manufacturing a remainder of the second portion from a second material, the first material being denser than the second material. 
     A further embodiment of the foregoing method, further includes the step of attaching the second portion of the rotating component to the first portion of the rotating component such that the second portion is maintained in a static position relative to the rotating component. 
     A gas turbine engine according to an exemplary embodiment of this disclosure, among other possible thing includes a compressor section, a combustor section fluidly connected to the compressor section, a turbine section fluidly connected to the combustor section, at least one rotating component having a retaining ring that at least partially comprises an additively manufactured portion, the part having a circumferential weight profile operable to counterbalance an unbalanced portion of the rotating component. 
     In a further embodiment of the foregoing gas turbine engine, the at least one rotating component is a rotor disposed in one of the compressor section and the turbine section. 
     In a further embodiment of the foregoing gas turbine engine, the at least one rotating component includes a plurality of additively manufactured portions. 
     In a further embodiment of the foregoing gas turbine engine, the additively manufactured portion of the part is a distinct component from a remainder of the retaining ring. 
     The foregoing features and elements may be combined in any combination without exclusivity, unless expressly indicated otherwise. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a gas turbine engine. 
         FIG. 2  schematically illustrates a cross section of a balanced rotating component including an additively manufactured portion. 
         FIG. 2A  schematically illustrates a simplified fore view of the balanced rotating component of  FIG. 2 . 
         FIG. 3  schematically illustrates a balanced rotating component including an additively manufactured secondary component. 
         FIG. 4  schematically illustrates a balanced rotating component including a additively manufactured balance ring. 
     
    
    
     DETAILED DESCRIPTION OF AN EMBODIMENT 
       FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B in a bypass duct defined within a nacelle  15 , while the compressor section  24  drives air along a core flow path C for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. 
     The exemplary engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine static structure  36  via several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided, and the location of bearing systems  38  may be varied as appropriate to the application. 
     The low speed spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor  44  and a low pressure turbine  46 . The inner shaft  40  may be connected to the fan  42  through a speed change mechanism, which in exemplary gas turbine engine  20  is illustrated as a geared architecture  48  to drive the fan  42  at a lower speed than the low speed spool  30 . The high speed spool  32  includes an outer shaft  50  that interconnects a high pressure compressor  52  and high pressure turbine  54 . A combustor  56  is arranged in exemplary gas turbine  20  between the high pressure compressor  52  and the high pressure turbine  54 . A mid-turbine frame  57  of the engine static structure  36  may be arranged generally between the high pressure turbine  54  and the low pressure turbine  46 . The mid-turbine frame  57  further supports bearing systems  38  in the turbine section  28 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via bearing systems  38  about the engine central longitudinal axis A which is collinear with their longitudinal axes. 
     The core airflow is compressed by the low pressure compressor  44  then the high pressure compressor  52 , mixed and burned with fuel in the combustor  56 , then expanded over the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  57  includes airfoils  59  which are in the core airflow path C. The turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. It will be appreciated that each of the positions of the fan section  22 , compressor section  24 , combustor section  26 , turbine section  28 , and fan drive gear system  50  may be varied. For example, gear system  50  may be located aft of combustor section  26  or even aft of turbine section  28 , and fan section  22  may be positioned forward or aft of the location of gear system  48 . 
     The engine  20  in one example is a high-bypass geared aircraft engine. In a further example, the engine  20  bypass ratio is greater than about six (6), with an example embodiment being greater than about ten (10), the geared architecture  48  is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3 and the low pressure turbine  46  has a pressure ratio that is greater than about five. In one disclosed embodiment, the engine  20  bypass ratio is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor  44 , and the low pressure turbine  46  has a pressure ratio that is greater than about five 5:1. Low pressure turbine  46  pressure ratio is pressure measured prior to inlet of low pressure turbine  46  as related to the pressure at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. The geared architecture  48  may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including direct drive turbofans. 
     A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section  22  of the engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft, with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.45. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R)/(518.7°R)] 0.5 . The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 ft/second. 
       FIG. 2  schematically illustrates a rotating component  100 , such as a compressor rotor or a turbine rotor for use in the turbine engine  20  illustrated in  FIG. 1 . The rotating component  100  includes a radially outward protruding portion  110  to which rotor blades that protrude into the core flowpath C (illustrated in  FIG. 1 ) can be mounted, the rotor blades interact with adjacent static components (referred to as stators) to generate compression (for a compressor rotor) or to drive a turbine shaft (for a turbine rotor) according to known gas powered turbine principles. The rotating component  100  is connected to a shaft  150  via a root portion  120 . In one example, the shaft  150  is the low speed spool  30 . In another example, the shaft  150  is the high speed spool  32 . 
     Due to variances in engine designs and manufacturing tolerances many rotating components  100  have an uneven circumferential weight distribution. The uneven circumferential weight distribution results in an overweight region  130  that is effectively overweight relative to the remainder of the rotating component  100 . As the rotating component  100  rotates within the gas turbine engine  20 , the overweight region  130  throws off the balance of the rotating component  100  and causes engine vibrations. In order to balance the overweight region  130  and reduce the engine vibrations, a corresponding counterweight region  140  is constructed and offset from the overweight region  130 . The counterweight region  140  is positioned to create a radial symmetry within the rotating component  100  and achieve an even circumferential weight distribution. 
       FIG. 2  illustrates a side cross sectional view of a rotating component  100 .  FIG. 2A  illustrates a simplified fore view of the rotating component  100 . The simplified fore view omits certain elements of the component for explanatory purposes. In the example illustrated in  FIGS. 2 and 2A , the rotating component  100  includes a rotor blade  110 , connected to a rotor disc  112 . The rotating component  100  further includes cover plates  114  connected to each axial side of the rotating component  100 . In the simplified fore view of  FIG. 2A  the fore coverplate  114  is omitted and the aft coverplate  114  is partially obscured. In alternate examples, the rotating component  100  only includes a cover plate  114  on one axial side. The cover plates  114  are retained in position via a retaining ring  120  that interfaces with the disc  112  and the cover plate  114 . 
     In the illustrated example of  FIGS. 2 and 2A , the rotor blade  110  includes an overweight region  130 . The overweight region causes the weight distribution of the rotor to be circumferentially uneven, and will cause vibrations within the engine without a suitable counterweight. 
     The retaining ring  120  is constructed using an additive manufacturing process. Additive manufacturing techniques are colloquially referred to as “3D printing”, and allow an individual component to be created by sequentially applying individual layers of a material to a substrate, with each layer having a specific two dimensional profile. The buildup of the sequentially applied layers creates a three dimensional structure based on the two dimensional profiles. 
     In the illustrated example of  FIG. 2 , the particulars of the imbalance (i.e., the overweight region  130 ) of any given rotor  110  can be determined prior to the manufacturing of the retaining ring  120 , and the retaining ring  120  is correspondingly additively manufactured with the inclusion of the counterweight region  140 , thereby creating a custom balanced rotating component for any given application. 
     Utilizing the additive manufacturing technique to create the retaining ring  120  of the rotating component  100 , allows the counterweight region  140  to be created integrally to an existing part in the rotating component  100 , and an additional balance ring, or separate counterweight component is not required in the example of  FIG. 2 . 
     In the illustrated example of  FIG. 2 , the majority of the retaining ring  120  is manufactured from a suitable additive manufacturing material with a relatively low density. The counterweight region  140 , however, is created from a second material, or compilation of materials with a relatively high density. The two materials can be integrally created with a single overall profile resulting in the illustrated retaining ring  120 . The utilization of two distinct materials allows the counterweight region  140  to be denser than the remainder of the retaining ring  120 , thereby causing the counterweight region  140  to be heavier and countering the overweight region  130 . By constructing the retaining ring  120  in this manner, a preset dimensional profile of the retaining ring  120  can be utilized, while still incorporating the counterweight region  140 . In this example, the weight profile of the counterweight region  140  is determined by the ratio of the denser material to the lighter material throughout the counterweight region  140 . 
     In alternate examples, the counterweight region  140  and the remainder of the retaining ring  120  are constructed of the same material, and the counterweight region  140  has physical dimensions that vary from the remainder of the retaining ring  120 . The variance in physical dimension increases the weight in the counterweight region  140  and achieves the counterweighting function. 
     Furthermore, while the counterweight region  140  is described as being incorporated in the retaining ring  120 , one of skill in the art having the benefit of this disclosure would recognize that any part of the rotating component  100  suitable for additive manufacturing could include the counterweight region  140 , and provide the same benefit. 
       FIG. 3  illustrates an alternate example rotating component  200 , including a distinct counterweight component  240  that is slotted into a receiving slot  242  located in a root portion of the rotating component  200  to create a balanced rotating component  200 . As with the example of  FIG. 2 , the base rotating component  200  includes a rotor portion  210  for mounting rotor blades and a retaining ring  220  for connecting to shaft  250 . The retaining ring  220  and the rotor portion  210  of the rotating component  200  are constructed using standard rotor creation methods. The counterweight slots  242  are distributed circumferentially about the rotating components  200 , thereby ensuring that the rotating component  200  is circumferentially balanced, with the exception of the overweight regions  230 ,  230   a . In some alternate examples, the counterweight slots  242  are positioned in other portions of the rotating component  200  and not in the retaining ring  220 . In the alternate examples, the counterweight slots  242  are also distributed evenly circumferentially. 
     During manufacturing, the rotating component  200  is tested to determine if any overweight regions  230 ,  230   a  exist, and where any overweight regions  230 ,  230   a  are located. The particular weight profile of any overweight regions  230  is also determined at this stage. The weight profile of the overweight region  230  is the circumferential distribution of the weight in the overweight region, and determines the weight profile needed in a counterweight  240  designed to counter the overweight region  230 . 
     The illustrated example of  FIG. 3  includes two overweight regions  230 ,  230   a . The first overweight region  230  is approximately centered over a counterweight slot  242  and has another counterweight slot  242  positioned 180 degrees offset from the overweight region  230 . For the first overweight region  230 , a single counterweight  240  can be designed to balance the overweight region  230 . The single counterweight  240  is received and retained in the counterweight slot  242  that is 180 degrees offset from the first overweight region  130 . 
     The second overweight region  230   a  does not have a counterweight slot  242  approximately 180 degrees offset from the overweight region  230   a . As such, two counterweight slots  242  receive corresponding counterweights  240   a  designed to cooperatively counter the overweight region  230 . The weight profiles of the two counterweights  242   a  are designed to cooperatively balance the overweight region  230   a . Once the weight profiles of the overweight regions  230  are determined, the corresponding counterweight  240  (or multiple corresponding counterweights  240   a ), for each of the overweight regions  230 ,  230   a  is designed according to known balancing techniques and printed using the additive manufacturing technique as necessary. 
     In one example, the remaining counterweight slots  242  that do not receive and retain counterweights  240 ,  240   a  are filled in with low mass “blank” counterweights that minimally affect the weight distribution of the rotating component  200 . In alternate examples, the counterweight slots  242  that do not receive and retain counterweights  240 ,  240   a  are left empty. 
       FIG. 4  illustrates another example embodiment of a rotating component  300 , where an additively manufactured counterweight  360  is created as an entirely separate component and received within the rotating component  300  or otherwise connected to the rotating component  300 . As with the previous examples, the rotating component  300  is connected to a shaft  350  and includes a rotor portion  310  for mounting rotor blades and a retaining ring  320  for connecting the rotor portion  310  to the shaft  350 . 
     Similar to the example illustrated in  FIG. 3 , the rotating component  300  is manufactured according to known techniques and is tested to determine the location of any overweight regions  330 . Once the overweight regions  330  are determined, a counterweight component  360 , such as a balance ring, can be additively manufactured to the exact counterweight profile required to balance the rotating component  300 . 
     The example counterweight component  360  is a balance ring including a thin ring shaped body portion  366  and a split opening  364  for mounting the balance ring to the rotating component  200 . The counterweight regions  362  are built up via additive manufacturing and are designed in a manner to counteract the unbalanced region  330 . In alternate examples, the additively manufactured balancing component  360  can be a rotor cover, or any other rotor component that is attached to the rotating component  300  in a standard turbine engine configuration and is maintained in a static position relative to the rotating component  300 . 
     While the examples illustrated in  FIGS. 2-4 , and described above, are directed toward a rotating component for use in a gas turbine engine, it is further understood that the same techniques can be applied to a rotating component for any gas powered turbine, including a land based turbine, and are not limited to turbine engines for aircraft. 
     It is further understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.