Abstract:
An improved method for flushing the residue from internal surfaces of cavities in, for example, turbine blades. In accordance with one aspect of the invention, provision is made for simultaneously flushing the internal cavities of a plurality of turbine blades, with each blade having a plurality of cavities therein.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This invention relates to U.S. patent application Ser. No. 10/271,681 entitled Apparatus and Method for Cleaning Airfoil Internal Cavities, filed on Oct. 15, 2002, and assigned to the assignee of the present invention and which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   This invention relates generally to parts, such as turbine blades, that have internal cavities and, more particularly to a method and apparatus for cleaning the internal cavities thereof. 
   In the manufacture or repair of turbine blades of the type used in the high pressure turbine of a gas turbine engine, the internal cavities of the blade are left with a residue of undesirable foreign material such as salts, silicone and silk, which must be removed from the internal cavities in order to obtain proper performance therefrom. In addition, the foreign material can collect in corners or other such locations within the internal cavities. The usual method of cleaning these internal surfaces is to conduct an autoclave or ultrasonic cleaning operation, followed by a flushing out of the cavities by the use of a high pressure washing process. 
   The flushing process is commonly accomplished by using one or more probes to introduce a high pressure flow of a liquid such as water into one or more of the cavities in order to wash out the undesirable residue. 
   The apparatus for positioning the probes with respect to the blade cavity has generally been of two types. The one that has been used following the autoclave process was that of a single blade being flushed by a pair of probes simultaneously registering with their respective cavities, after which the probes were retracted and then indexed to the next blade for the same process. 
   Another prior art process that has been used after ultrasonic cleaning is that of a fixture having a pair of extended probes that separately register with individual cavities of two different blades. After the respective cavities have been cleaned, the fixture is retracted and then indexed to adjacent cavities in the same respective blades. 
   SUMMARY OF THE INVENTION 
   In accordance with one aspect of the invention, the apparatus for flushing turbine blades has a plurality of probes that are spaced in the plane in which a plurality of spaced blades are held in place such that a plurality of blades can be simultaneously flushed, and the apparatus also includes a plurality of probes in a plane in which the individual cavities of a single blade are disposed such that a plurality of cavities within a single blade can be simultaneously flushed. In this way multiple cavities and multiple blades can be simultaneously flushed in a single process. 
   In the drawings as hereinafter described, a preferred embodiment is depicted; however various other modifications and alternate constructions can be made thereto without departing from the true spirit and scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a longitudinal cross sectional view of a turbine blade as being flushed in accordance with the present invention. 
       FIG. 2  is a perspective view of an apparatus for simultaneously flushing a plurality of blades in accordance with one embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIG. 1 , a turbine blade of the type used in a high pressure turbine of a gas turbine engine is shown to include a root portion  11  at its one end and airfoil portion  12  at its other end. The airfoil portion  12  has a leading edge  13 , a trailing edge  14 , and a end wall  16  opposite the root portion  11 , as well as internal walls  17  and  18  which collectively define the internal cavities  19 ,  21  and  22  that extend generally longitudinally within the internal structure of the turbine blade. 
   The root portion  11  includes a plurality of serrations  23  on the outer side thereof to facilitate the attachment to corresponding features on the turbine rotor (not shown), and a plurality of root openings  24 ,  26  and  27  that lead to the internal cavities  19 ,  21  and  22 . When installed and operating, high pressure air is introduced into the root openings  24 ,  26  and  27  so as to flow through the cavities  19 ,  21  and  22  and to exit out the opening in the trailing edge  14  for purposes of cooling the blade. 
   During the cleaning process in the factory or repair facility, following an autoclave and/or ultrasonic cleaning process, a flushing process is applied to remove various types of undesirable residue from the interior of the blade by the circulation of high pressure fluid, such as water, through the cavities as indicated by the arrows. 
   As will be seen, a probe  28  is inserted into the cavity  19  to the extent that its end openings  29  is just past the radially outer end of the internal wall  17 . A high pressure fluid is then caused to flow through the tubular probe  28  and to be discharged from the end  29  such that it flows against the end wall  16  and back through the cavity  21  as indicated by the arrows. 
   Similarly, a probe  31  is introduced into the cavity  22  to the extent that it reaches well beyond the radially inner end of the internal wall  18 . A high pressure fluid, such as water at a pressure of around 10,000 psi, is caused to flow from the end  32  of the probe  31 , along the cavity  22  and out the openings in the trailing edge  14  as shown by the arrows. 
   Reference is now made to  FIG. 2  wherein there is shown apparatus for the simultaneous flushing of the internal cavities of a plurality of turbine blades. 
   A blade holder  33  includes a plurality of spaced chucks  34 ,  36 ,  37 , and  38  having serrations for receiving the root portion of the blades  39 ,  41  and  42 , therebetween. The blade holder  33  also includes a guide number  43  that is disposed transversely across and near the ends of the roots of the blades  39 ,  41  and  42 . The guide member  43  contains a plurality of passages whose axes are aligned with the root openings of the turbine blades as described hereinabove. That is, passages  44  and  46  have their axes aligned with respective root openings  24  and  27  of blade  39 , passages  47  and  48  have axes that are aligned with respective root openings  24  and  27  of blade  41  and passages  49  and  51  have axes that are aligned with root openings  24  and  27  of blade  42 . 
   Disposed opposite the guide member  43  is a manifold  52  which is reciprocally mounted on a base  62  having side guide members  63  and  64  and having a central guide member  66 , all of which act to maintain the fixed transverse position of the manifold  52  as it is retracted and advanced along those guide members. Such advancement and retraction may be accomplished by the manual grasping of a handle  68  and moving the manifold forwardly or backwardly on its base  62 . Alterantively, a hydraulic mechanism can be attached to the manifold  52  to advance or retract it along its path by the base  62  and its guide members  63 , 64  and  66 . 
   The manifold  52  is fluidly connected to a high pressure (e.g. 10,000 psi) fluid source such as water or the like. On the front side of the manifold  52  there are a plurality of discharge ports  53  extending outwardly and fluidly connected to respective probes or probe tubes whose axes are aligned with the axes of the respective passages in the guide member  43 . That is, probe  54  has its axis aligned with the axis of the passageway  44 , probe  56  has its axis aligned with the axis of passage  46 , probe  57  has its axis aligned with the axis of passage  47 , probe  58  has its axis aligned with the axis of passage  48 , probe  59  has its axis aligned with the axis of passage  49 , and probe  61  has its axis aligned with the axis of passage  51 . 
   As will be seen in  FIG. 2 , with each probe pair associated with a single turbine blade, one is longer than the other so as to accommodate the required insertion degrees. The particular probe combinations are unique to a particular turbine blade design. Further, the guide member  43 , and most likely the blade holder  33  with its various chucks, are to be used only with a particular design of turbine blade since the positioning of the turbine blade, the passages in the guide member  43  and the length and positioning of the various probes as held by the discharge port members  53 , must all be closely coordinated. Thus, for any one of the vertically spaced pairs of probes as shown in  FIG. 2 , only a single type of blade design may be cleaned with this process. Preferably, each of the three vertically spaced pairs is identical and is adapted for the cleaning of identical blade designs. 
   Considering now the steps in the process of cleaning a plurality of turbine blades, the manifold  52 , is moved to the retracted position with the probes being to the left of the guide member  43 . The blade holder  33 , with its installed blades, has been moved to a precise position opposite the manifolds  52  with the reference guide surface  69  acting to precisely locate the blade holder  33  on its right side, and with the lower guide surface  71  acting as a reference surface to precisely locate the blade holder  33  in the vertical plane. The manifold  52  and its extended probes are advanced, with the probes passing through the respective passages in the guide member and into their respective cavities of the blades. The fluid source  67  is then activated to force the high pressure flow of water into the cavities for removing any residue from the internal surfaces thereof. 
   After the cleaning process has been completed the manifold  53  is then retracted, and the blade holder  33  with its attached blades is then lifted from its position and moved to a more remote location so that its cleaned blades can be removed from the holder  33  and other blades are inserted therein such that the holder  33  can then be subsequently placed in position abutting the reference guide surface  69  and the lower guide surface  71  for a repeat of the process. 
   While the present invention has been particularly shown and described with reference to various embodiments as illustrated in the drawings, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the true spirit and scope of the invention as defined by the claims.