Abstract:
A sealing interface for a component in a turbine machine, wherein a plug is mechanically affixed within an entrance passage of an aperture. The plug is secured in place within the entrance passage through deformation of an inner end of the plug to cause the plug to mechanically engage a groove formed adjacent the entrance passage.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a plug for use in a turbine engine, and more particularly, to a plug which is mechanically affixed in a shroud crossfeed aperture. 
       BACKGROUND OF THE INVENTION 
       [0002]    In multistage rotary machines used for energy conversion, a fluid is used to produce rotational motion. In a gas turbine engine, for example, a gas is compressed in a compressor and mixed with a fuel source in a combustor. The combination of gas and fuel is then ignited for generating combustion gases that are expanded through a turbine to produce rotational motion. Both the turbine stage(s) and the compressor have stationary or non-rotary components, such as vanes, for example, that cooperate with rotatable components, such as rotor blades, for example, for compressing and expanding the operational gases. 
         [0003]    As temperatures within the machines become substantially high, it is important to cool components of the machine to prevent overheating that could lead to decreased performance, inefficiency, and/or failure, including melting. During development of the machines, cooling air passages are formed through shrouds that are affixed to the vanes and/or rotor blades. The air passages are used to transfer cooling air to areas of the vanes and/or rotor blades which are to be cooled. Typically, when these cooling air passages are formed in the shrouds, a crossfeed aperture may be formed in an end portion of the shroud. These apertures are subsequently sealed to prevent an escape of the cooling air. 
         [0004]    A known prior art technique for sealing these apertures by welding or brazing procedures can be time consuming. Such welding and brazing procedures can result in excess welding or brazing material being deposited in the cooling air passages. Once in the cooling air passages, this material can harden and subsequently limit cooling air flow causing inadequate cooling of the parts. Further, applying welding or brazing material to close off the apertures can adversely affect shroud machining operations, such as seal slot electrical discharge machining, in that the welding or brazing material may be harder and consequently less conducive to further machining operations. 
         [0005]    In view of the foregoing considerations it would be desirable to provide a plug for use in a shroud of a rotary machine, whereby the plug can be mechanically affixed in shroud crossfeed apertures, and wherein the plug permits performance of follow-up shroud machining operations. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with a first aspect of the present invention, a sealing interface is provided for a component in a turbine machine having cooled components. The component includes a bore extending into the component from an outer side wall thereof. The sealing interface comprises an entrance passage defining an outer end of the bore adjacent the outer side wall of the component, a shoulder surface defined at an end of the entrance passage distal from the outer side wall, and a plug located within the entrance passage. The plug includes a mechanical clamping portion adjacent the shoulder surface for mechanically retaining the plug within the entrance passage. 
         [0007]    In accordance with a second aspect of the present invention, a sealing interface is provided for a component in a turbine machine having cooled components. The component includes a bore extending into the component from an outer side wall thereof. The sealing interface comprises an entrance passage defining an outer end of the bore adjacent the outer side wall of the component. The entrance passage defines a first diameter of the bore. A fluid passage defines an inner portion of the bore defining a second diameter of the bore. A shoulder surface is defined at an end of the entrance passage distal from the outer side wall and extending radially between the entrance passage and the fluid passage. A plug is located within the entrance passage and includes a mechanical clamping portion adjacent the shoulder surface for mechanically retaining the plug within the entrance passage. 
         [0008]    In accordance with a third aspect of the present invention, a method is provided for sealing a bore formed in an outer side wall of a component of a turbine machine having cooled components. The method comprises the steps of inserting a plug into an entrance passage of the bore, causing the plug to contact a shoulder surface defined at an end of the entrance passage distal from the outer wall, and mechanically deforming the plug against the shoulder surface to mechanically retain the plug within the entrance passage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the present invention will be better understood from the following description in conjunction with the accompanying Drawing Figures, in which like reference numerals identify like elements, and wherein: 
           [0010]      FIG. 1  is an exploded perspective partial cutaway view of a component and a plug which form a sealing interface in accordance with an embodiment of the invention; 
           [0011]      FIG. 2  is a side cross sectional view of the sealing interface illustrated in  FIG. 1  showing the plug in a partially inserted position; 
           [0012]      FIG. 3  is a side cross sectional view of the sealing interface showing the plug in a fully inserted position; and 
           [0013]      FIG. 4  is a side cross sectional view of the sealing interface after follow-up machining operations have been performed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, specific preferred embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. 
         [0015]    According to aspects of the present invention, a sealing interface  10  implemented in a gas turbine engine (not shown) having cooled components is shown in  FIGS. 1-4 . The sealing interface  10  is formed by a component  12  and a plug  14 , as shown in  FIG. 1 . In the embodiment shown, the component  12  is a non-rotating vane shroud mounted to a non-rotating vane assembly  15 , although the sealing interface  10  described herein may be incorporated in other types of components including, without limitation, a shroud for a rotating turbine blade. 
         [0016]    As seen in  FIGS. 1 and 2 , the component  12  includes a generally flat outer side wall  16 . A bore  18  having a longitudinal axis Lb is formed in the component  12 , extending inwardly from the side wall  16 . The bore  18  is in fluid communication with cooling fluid passages  20  which are also formed in the component  12 . While a plurality of cooling fluid passages  20  are shown, it is understood that additional or fewer cooling fluid passages can be formed in the component  12  and in fluid communication with the bore  18  without departing from the scope and spirit of the invention. 
         [0017]    An outer end  21  of the bore  18  defines an entrance passage  22  of generally circular cross-section and having a substantially constant diameter. It is understood that the entrance passage  22  can have other suitable shapes as desired. An undercut portion  23  defined by undercut groove  24  is formed in the component  12  at an inner end  26  of the entrance passage  22 . A diameter d 1  of the undercut groove  24  is larger than a diameter d 2  bore  18 , and is larger than a diameter d 3  of the entrance passage  22 . Further, the diameter d 2  of the bore  18  is smaller than the diameter d 3  of the entrance passage  22 . A shoulder surface  27  is formed at the inner end  26  of the entrance passage  22  extending radially between the undercut groove  24  and the bore  18  and extending substantially perpendicular to the longitudinal axis Lb of the bore  18 . The shoulder surface  27  defines a transition from the diameter d 3  of the entrance passage  22  to the diameter d 2  of the bore  18 . 
         [0018]    In the embodiment described, the plug  14  is formed from an INCONEL alloy (INCONEL is a registered trademark of Special Metals Corporation), although any suitable malleable material may be used to form the plug  14  as desired. In the embodiment shown, a length L of the plug  14  is at least as long as a depth D of the entrance passage  22  of the component  12 , although the plug  14  may have any suitable length. The plug  14  includes a cylindrical, elongate main body  28  having a substantially constant diameter d 4 . In a preferred embodiment, the diameter d 4  of the main body  28  is slightly smaller than the diameter d 3  of the entrance passage  22 . A relatively close fit between the main body  28  and the entrance passage  22  facilitates insertion through the entrance passage  22  and additionally ensures alignment of the plug  14  within the entrance passage  22 . 
         [0019]    Referring to  FIGS. 2 and 3 , a mechanical clamping portion  30  is formed at an inner end  32  of the main body  28 . The mechanical clamping portion  30  includes a radially extending flange  34 . The flange  34  is adapted to engage the undercut groove  24  of the component  12 . A first surface  33  of the flange  34  is adapted to engage the shoulder surface  27 . The engagement of the first surface  33  to the shoulder surface  27  may create a substantially fluid tight seal therebetween. A second surface  35  of the flange  34  is adapted to engage an annular outer surface  37  of the undercut groove  24 . The mechanical clamping portion  30  has an annular area of reduced diameter  36  formed between the flange  34  and the main body  28 . The area of reduced diameter  36  forms a substantially smooth concave transition from the main body  28  to the flange  34 . The area of reduced diameter  36  is adapted to provide clearance from an edge  38  between the entrance passage  22  and the undercut groove  24  when the plug  14  is installed in the bore  18 . The mechanical clamping portion  30  also includes a curved surface  39  having a concave side facing the cooling fluid passage  20 . 
         [0020]    A process of forming the sealing interface  10  will now be described. At least one cooling fluid passage  20  is formed in the component  12 , such as by an electro-discharge procedure, drilling, or other process known in the art. The bore  18  is then formed in the component  12  in fluid communication with the cooling fluid passages  20 , such as by an electro-discharge procedure, drilling, or other process known in the art. Once the bore  18  is formed in the component  12 , the entrance passage  22  and the undercut groove  24  may be formed in the component  12  by any known process. For example, an orbital electro-discharge procedure, although other means for forming the undercut groove  24  may be used. The formation of the entrance passage  22  and the undercut groove  24  also forms the shoulder surface  27  and the edge  38  between the entrance passage  22  and the undercut groove  24 . 
         [0021]    The plug  14  is separately formed to desired specifications. Once formed, the plug  14  is aligned with the bore  18  to a position, as shown in  FIG. 1 . The plug  14  is then inserted into the entrance passage  22  to a position, as shown in  FIG. 2 , by applying an insertion force to the main body  28  of the plug  14  in the direction of the inner end  26  of the of the entrance passage  22 . The force can be applied as a pushing force or a striking force, for example. Once the flange  34  of the plug  14  reaches the shoulder surface  27 , continued insertion force against the main body  28  of the plug  14  into the entrance passage  22  causes the flange  34  to engage the undercut groove  24  and deform into the shape shown in  FIG. 3 . The area of reduced diameter  36  and the curved surface  39  create a thin wall area to promote a predictable deformation of the plug  14 . Specifically, the area of reduced diameter  36  and the curved surface  39  cause the flange  34  to deform radially outwardly and also axially back toward the main body  28  of the plug  14 . In the embodiment shown, the flange  34  does not completely fill the area defined by the undercut groove  24 . However, it is understood that the flange  34  could be designed to fill more or less of the area defined by the undercut groove  24 , or could be designed to fill the entire area defined by the undercut groove  24 , without departing from the scope and spirit of the invention. 
         [0022]    Optionally, a feature may be provided on the plug  14  for identifying or controlling the depth of insertion into the bore  18 . For example, an engraved or raised feature (not shown) may be formed on the plug  14  which may become flush with the side wall  16  when fully inserted into the bore  18 . Alternatively, the plug  14  may have at least a partially tapered diameter to assist in properly inserting the plug  14  to a correct depth within the bore  18 . In this case, the outer surface of the plug  14  could be designed to contact the side wall  16  to prevent further insertion into the bore  18  once the plug  14  is inserted to the correct depth. 
         [0023]    Deformation of the flange  34  within the undercut groove  24  to affix the plug  14  within the entrance passage  22  prevents withdrawal of the plug  14  from the entrance passage  22 . This affixation is performed without the need for additional procedures, such as welding or brazing. Further, the contact between the first surface  33  of the flange  34  and the shoulder surface  27  may be provided to create a substantially fluid tight seal between the component  12  and the plug  14 . It should be understood that a substantially fluid tight seal could additionally or alternatively be created by engagement of the main body  28  of the plug  14  with the surrounding wall of the entrance passage  22 . In this case, a plug having a tapered diameter as described above could assist in creating the substantially fluid tight seal by contacting the surrounding wall of the entrance passage  22 . Alternatively, an outer end  40  of the plug  14  could be expanded, such as by striking the outer end  40  with a punch (not shown), for example. In this case, any excess length of the plug  14  extending outwardly beyond the outer side wall  16  would be removed and the punch would then expand the second end  40  of the plug  14  to fill the surrounding area of the entrance passage  22  to eliminate clearance between the plug  14  and the entrance passage  22 . Additionally, contact between the second surface  35  of the flange  34  and the annular outer surface  37  of the undercut groove  24  may be provided to limit axial movement between the plug  14  and the component  12  and/or to provide additionally sealing surfaces. 
         [0024]    Moreover, the malleable material used to form the plug  14  permits the application of follow-up machining operations. In particular, by affixing the plug  14  within the entrance passage  22  in such a manner that substantially only malleable material is present adjacent the outer side wall  16 , i.e., without additional relatively hard material typically associated with brazing and/or welding, the outer end  40  of the plug  14  may be machined or shaped. For example, various machining or shaping operations may be performed on the outer end  40  of the plug  14  including, without limitation, surface grinding to provide a desired finish of the component/plug structure, or electrical discharge machining to form an axial slot  42  in the component/plug structure, as shown in  FIG. 4 . The slot  42  may be adapted, for example, to receive an elongate fastener (not shown) that is used to affix adjacent components (not shown) to the component  12 , as is known in the art. 
         [0025]    It should be noted that although the present embodiment of the invention is described with reference to forming a substantially fluid tight seal, the sealing interface  10  may be utilized to provide a closure to an opening in which the engagement of the flange  34  within the groove  24  may or may not completely seal the bore  18  at the entrance passage  22 , e.g., to provide a restriction to passage of fluid. 
         [0026]    While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.