Abstract:
A automated sealing assembly for rotary machines including: a seal guide assembly, the seal guide assembly aligns and holds a caulk wire and a sealing strip in a rotor groove for peening; a peening tool, the peening tool peens said caulk wire to deform the caulk wire and secure the caulk wire and the sealing strip in the rotor groove; an actuator, the actuator controls a movement and preload force of the peening tool producing a rotor groove seal having a predictable pull out strength; and a base for securing the seal guide assembly, the peening tool, and the actuator.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to sealing assemblies for rotary machines and, more particularly, to a sealing assembly for a steam or gas turbine. 
   Rotary machines include, without limitation, steam turbines, compressors, and gas turbines. A steam turbine has a steam path that typically includes, in serial-flow relationship, a steam inlet, a turbine, and a steam outlet. A gas turbine has a gas path, which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine, and a gas outlet (or exhaust nozzle). Gas or steam leakage, either out of the gas or steam path or into the gas or steam path, from an area of higher pressure to an area of lower pressure, is generally undesirable. For example, gas path leakage in the turbine or compressor area of a gas turbine, between the rotor of the turbine or compressor, and the circumferentially surrounding turbine or compressor casing, will lower the efficiency of the gas turbine leading to increased fuel costs. Also, steam-path leakage in the turbine area of a steam turbine, between the rotor of the turbine and the circumferentially surrounding casing, will lower the efficiency of the steam turbine leading to increased fuel costs. 
   To reduce gas and steam-path leakage in gas and steam turbine engines, sealing assemblies are used. In various types of turbine sealing assemblies, rotor groove sealing strips are disposed between rotary and stationary components of the turbine engine. Presently, the rotor groove sealing strips are peened using a variety of methods. One method includes, but is not limited to, grinding a curved tip on a hand chisel that is impacted by a hand held hammer to deform or peen wire in a groove. Another method includes grinding a curved tip in a hand held pneumatic vibratory hammer to peen caulk wire into the groove. The current methods of peening the caulk wire, however, do not consistently achieve a high pull out strength of a rotor groove seal created by the peened caulk wire. 
   Maximizing the pull out strength of the rotor groove seal is important because the rotor groove seal experiences several pullout forces during operation of the turbine. Such forces include, but are not limited to, a centrifugal pull out force, a moment force at the base of the seal due to steam pressures, and radial and tangential forces during metal-to-metal rub, as well as rub against abradable type coatings intentionally applied to a housing defining the steam path. It is therefore desirable to have a rotor groove seal with a predictably high pull out strength. 
   Additionally, the current methods of peening the caulk wire result in unrepeatable peening such that this peening causes unpredictable seal pull out strengths. The wide variance in seal pull out strengths is due to a variety of factors including, but not limited to, improper positioning of the peening tool by the operator and inconsistent forces applied with the peening tool. For example, the standard deviation of the seal pull out strengths produced by hand peening can be as large as 200 pounds in a population that has a mean seal pull out strength of 600 pounds. The wide variance in seal pull out strength is problematic because low seal pull out strengths can result in seals coming loose during operation and result in significant damage to the turbine including down time of the same. 
   Accordingly, it would be desirable to develop a cost effective sealing method and apparatus that can produce rotor groove seals having a predictable seal pull out strength, without impairing the performance of the sealing strips. 
   BRIEF DESCRIPTION OF THE INVENTION 
   Disclosed herein is an automated sealing assembly for rotary machines including: a seal guide assembly, the seal guide assembly aligns and holds a caulk wire and a sealing strip in a rotor groove for peening; a peening tool, the peening tool peens said caulk wire to deform the caulk wire and secure the caulk wire and the sealing strip in the rotor groove; an actuator, the actuator controls a movement of the peening tool producing a rotor groove seal having a predictable pull out strength; and a base for securing the seal guide assembly, the peening tool, and the actuator. 
   Also disclosed herein is a method for automated sealing of a rotary machine, the method including: aligning a caulk wire and a sealing strip with a rotor groove; holding the caulk wire and the sealing strip for peening in the rotor groove with a seal guide assembly; peening the caulk wire with a peening tool, movement of the peening tool being controlled by an actuator; moving the peening tool with the actuator; and wherein peening the caulk wire deforms the caulk wire and creates a rotor groove seal with a predictable pull out strength. 
   Also disclosed herein is a system for automated sealing of a rotary machine, the system including: means for aligning a caulk wire and a sealing strip with a rotor groove; means for holding the caulk wire and the sealing strip for peening in the rotor groove with a seal guide assembly; means for peening said caulk wire with a peening tool, movement of said tool being controlled by an actuator; means for moving the peening tool with the actuator; and wherein said means for peening the caulk wire creates a rotor groove seal with a predictable pull out strength. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
       FIG. 1  is a cross-sectional, schematic view of an exemplary rotary machine; 
       FIG. 2  is an enlarged, detailed view of portion X of  FIG. 1  showing an exemplary rotor groove seal; 
       FIG. 3  is a schematic of an exemplary embodiment of an automated sealing assembly; and 
       FIG. 4  is a schematic of an exemplary embodiment of a seal guide assembly. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As illustrated in  FIG. 1 , a typical rotary machine  50  such as a steam turbine (also indicated by reference numeral  50 ), typically includes at least one rotary component, such as a rotor  54  and rotating buckets  56 , and a stationary component  58 , such as a stationary steam nozzle (also indicated by reference numeral  58 ) surrounding the rotor  54 . The rotor  54 , rotating buckets  56 , and the stationary components  58  are disposed circumferentially around a common axis  60 . For the rotary machine  50 , steam passing through the stationary nozzles  58  is directed at a high velocity against the rotor  54  causing it to rotate at a high speed. 
   A rotor groove seal  62  is described first with reference to  FIG. 1 . As shown, the rotor groove seal  62  is disposed between the rotor  54  and the stationary component  58 . Referring also to  FIG. 1 , the rotor groove seal  62  includes at least one sealing strip  66 , which is affixed to either rotor  54  or the stationary component  58 .  FIGS. 1 and 2  illustrate embodiments of the rotor groove seal  62 , for which at least one sealing strip  66  is affixed to the rotor  54 . As shown in  FIG. 2 , a series of sealing strips  66 , such as a J strip seal (also indicated by reference numeral  66 ), may be affixed to the rotor  54 , located in a rotor groove  28 , by a caulk wire  30 . 
   As illustrated in  FIG. 3 , an automated sealing assembly  10  is shown which includes a seal guide assembly  12 , a peening tool  14 , an actuator  16 , and a base  18 . The seal guide assembly  12  may contain one or more rotary guides  26  and block guides  24 . The peening tool  14  may be any tool suitable for peening a caulk wire  30  including, but not limited to, a hammer or a chisel with a radiused tip. The actuator  16  may be a pneumatic, an electric, or a hydraulic actuator. However, any other suitable means known to those of ordinary skill in the art of actuators is envisioned. In an exemplary embodiment, the base  18  is designed to align with the stand of a machining lathe or an assembly lathe to orientate the peening tool  14  with the rotor groove  28 . 
   The seal guide assembly  12  is affixed to a first slide assembly  22 , which is affixed to the base  18  such that the seal guide assembly  12  will properly align the caulk wire  30  for peening by the peening tool  14 . The seal guide assembly  12  may be positioned such that the seal guide assembly  12  inserts the caulk wire  30  and the sealing strip  66  into the rotor groove  28  before peening. The first actuator  16  is affixed to a second slide assembly  32 , which is affixed to the base  18 , and the peening tool  14  is affixed to the first actuator  16 . The peening tool  14  is oriented to impact the caulk wire  30  while the caulk wire  30  is located inside the rotor groove  28 . The peening tool  14  produces a rotor groove seal  62  with a predictable pull out strength by repeatedly striking the caulk wire  30  responsive to the control of the first actuator  16 . 
   In an exemplary embodiment, the first slide assembly  22  controls the force and position of the seal guide assembly  12 . The slide assembly  22  is affixed to the base  18  and the seal guide assembly  12  is affixed to the slide assembly  22 . The slide assembly  22  allows retraction of the seal guide assembly  12  to facilitate assembly of the caulk wire  30  and the sealing strip  66 . In another exemplary embodiment, a second slide assembly  32  controls the position and force of the peening tool  14  and first actuator  16 . The second slide assembly  32  is affixed to the base  18  and the first actuator  16  is affixed to the slide assembly  32 . The second slide assembly  32  can control the position of the peening tool  14  by controlling the position of the first actuator  16  to which the peening tool  14  is affixed. 
   In an exemplary embodiment, a second actuator  20  is affixed to the base  18  and connected to the slide assembly  22 . The second actuator  20  is used to control the position of and the force exerted by the seal guide assembly  12  relative to the caulk wire  30 . In another exemplary embodiment, a third actuator  34  may be affixed to the base  18  and connected to the first actuator  16 . Additionally, the third actuator  34  may also be used to control the position of and force exerted by the peening tool  14  relative to the caulk wire  30 . The third actuator  34  can control the force exerted by the peening tool  14  by controlling the force exerted by the first actuator  16  to which the peening tool  14  is affixed. Both the second actuator  20  and the third actuator  34  may be a pneumatic, an electric, or a hydraulic actuator. However, any other suitable means known to those of ordinary skill in the art of actuators is envisioned. 
   The first actuator  16 , the second actuator  20 , and the third actuator  34  may have a control valve with three modes, forward, reverse, and neutral. The neutral control valve mode allows the operator to manually position the seal guide assembly  12  and the first actuator  16  respectively. In an exemplary embodiment, the first actuator  16 , the second actuator  20 , and the third actuator  34  may have a neutral mode that can be activated by an emergency stop button located on the automated sealing assembly  10 . In an exemplary embodiment, both the second actuator  20  and the third actuator  34  may be pneumatic and the neutral mode vents the pressure of the second actuator  20  and the third actuator  34  to the surrounding atmospheric pressure. 
   In an exemplary embodiment, the automated sealing assembly  10  is positioned such that the peening tool  14  and the seal guide assembly  12  are properly aligned with a rotor groove  28  such that a caulk wire  30  can be peened. The automated sealing assembly  10  may be aligned for peening using several methods including, but not limited to, a laser guide affixed to the automated sealing assembly which projects a laser to be aligned with the rotor groove  28 . The first slide assembly  22  and the second slide assembly  32  are used for adjusting the position of the seal guide assembly  12  and the first actuator  16 , respectively. Additionally, the second actuator  20  is used to control the force exerted by the seal guide assembly  12  and third actuator  34  is used to control the force exerted by the peening tool  14 , both relative to the caulk wire  30 . The seal guide assembly  12  feeds, aligns, and holds the caulk wire  30  for peening by the peening tool  14 . The caulk wire  30  is intentionally and repeatably impacted by peening tool  14  during peening, the deformed caulk wire  30  secures the sealing strip  66  in rotor groove  28 . The peening tool  14  peens the caulk wire  30  in a manner controlled by the first actuator  16  and the third actuator  34  to produce a rotor groove seal  62  with a predictable seal pull out strength. 
   In another exemplary embodiment, the peening tool  14  may be a chisel with a hardened tip ground to have a tip thickness, which fits in the rotor groove  28  touching the caulk wire  30  to be peened. The peening tool  14  may have one side that is flat with the body of the peening tool  14  to ride just adjacent to the side of a J seal strip  66 . The other side of the peening tool  14  may be blended down to the tip width leaving a tip length to provide clearance for the seal height. To ensure smooth motion of the peening tool  14  on the face of the caulk wire  30  as the peening tool  14  moves along the caulk wire  30  during peening, the width of the tip of the peening tool  14  may be ground to have radiused corners. 
   Turning now to  FIG. 4 , the seal guide assembly  12  is shown that may include one or more rotary guides  112 ,  122 . Rotary guides  112 ,  122  are differentiated by an upper rotary guide  112  that may have a groove on its circumference to accept, hold, and guide the caulk wire  30  and sealing strip  66  for peening. The upper rotary guide  112  is connected to a rectangular block  114  with one or more slotted holes  116  and the position of the upper rotary guide  112  is fine-tuned by a position screw  118 . Similarly, the lower rotary guide  122  may be located below the upper rotary guide  112 . The lower rotary guide  122  provides more precise positioning of the caulk wire  30  and sealing strip  66  deeper in the rotor groove  28  before peening. The lower rotary guide  122  is connected to a rectangular block  124  with one or more slotted holes  126  and the position of the lower rotary guide  122  is fine-tuned by a position screw  128 . 
   In addition to rotary guides  112 ,  122 , seal guide assembly  12  may include one or more block guides  132 . A block guide  132  may be located below the lower rotary guide  122 . The block guide  132  may have a face contoured to the rotor  54  to hold the sealing strip  66  and the caulk wire  30  from coming out of the rotor groove  28  during peening. The block guide  132  may be located above the peening tool  14 . The block guide  132  contains one or more slotted holes  136 . The position of the block guide  132  is fine-tuned by a position screw  138 . The fine tuned position of the upper rotary guide  112 , the lower rotary guide  122 , and the block guide  132  are independent of the position of the other components of the seal guide assembly  12  mounted on the first slide assembly  22 . It is noted that the terms “upper” and “lower” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. 
   In an exemplary embodiment, a data logger  38  may be used to monitor and display both pressure and force data measured from the second actuator  20 , the third actuator  34 , and/or the first actuator  16 . The data logger  38  may also have a display  36  that displays the current pressure and force data measured from the second actuator  20 , the third actuator  34 , and/or the first actuator  16 . The data logger  38  optionally may record the pressure and force data onto any suitable means including, but not limited to, a computer readable medium such as a flash memory card or diskette. In an exemplary embodiment, the data logger  38  measures the pressure and force data on time intervals selected by the operator. In another exemplary embodiment, the data logger  38  may be located in a control cabinet that has a slot to accept a computer readable medium. The computer readable medium may be removed from the control cabinet and read by a computer for statistical analysis and production quality records. Optionally, the data logger  38  may have an alert system operable for alerting the operator if a monitored pressure and/or force is outside of a range specified by the operator. 
   In an exemplary embodiment, the operator is able to precisely control one or more operational parameters of the automated sealing assembly  10 . The operational parameters of the automated sealing assembly  10  include, but are not limited to, the angle of the peening tool  14  relative to rotor groove  28 , the frequency and magnitude of the movement of peening tool  14 , the dwell time of the peening tool  14  on the caulk wire  30  as a function of the rotational speed of the rotor  54 , and the force exerted by seal guide assembly  12  and first actuator  16  relative to the caulk wire  30 . Optionally, all of the above listed operational parameters may be controlled within specified ranges and a data logger may record the operational parameters for quality control purposes. Furthermore, all of the above listed operational parameters may also be shown to the operator using a suitable display. Such suitable display may include, but is not limited to, an analog gauge or digital display. 
   Using an automated sealing assembly  10  as disclosed herein it is possible to produce rotor groove seals  62  with a predicable pull out strength. In an exemplary embodiment, rotor groove seals  62  can be made using a 29-mil J seal  66 . The rotor groove seal  62  could have a mean pull out strength of approximately 1300 pounds and a standard deviation of approximately sixty-five pounds. The seal pull out strength and standard deviation created using the automated sealing assembly far exceeds the seal pull out strength and standard deviation that are typically achieved through currently available methods, such as hand peening. 
   While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.