Abstract:
A method of manufacturing a brush seal assembly is disclosed. The method includes circumferentially arranging bristles about an axis. A plate is arranged adjacent to the bristles. Unwelded ends of the bristles are aligned with a periphery of the plate to provide a flush surface across the plate and bristles. The unwelded ends are laser welded to the periphery at the flush surface to provide a unitary subassembly.

Description:
BACKGROUND 
     This disclosure relates to a brush seal assembly. More particularly, the disclosure relates to a method of securing bristles to a plate. 
     Brush seals are widely used to seal rotating structures. For example, the use of brush seals are prevalent in gas turbine engines. Typical brush seal manufacturing methods require numerous steps during which various components are welded to one another, which greatly impacts the manufacturing time and cost of the brush seal. 
     A brush seal typically includes at least three components: a bristle assembly or hoop and first and second plates arranged on either side of the bristle assembly. The plates and bristle assembly are joined to one another by various welds. One typical manufacturing process includes arranging the bristles in a fixture and securing a periphery of the bristles using a weld bead to provide the bristle assembly. The weld bead must then be machined to provide a smooth surface for subsequent welding operations. The machined bristle assembly is arranged between the plates and a weld bead is applied across the machined periphery and adjoining surfaces of the plates. 
     Typically, the components of the brush seal are tungsten inert gas (TIG) manually welded by a highly skilled welder. Automated laser welding, although suggested in the prior art, cannot be used because the machined surface of the bristle assembly must run true to the adjoining surface on the detail, which it does not. If adjoining surfaces are not true to one another, then porosity results in the weld when laser welding is employed, which renders the brush seal scrap. Moreover, since the orientation of the bristles is directional, the bristle assembly has been oriented and secured incorrectly relative to the plates, which renders the brush seal scrap. 
     What is needed is a brush seal manufacturing process that enables the use of automated laser welding and prevents improper orientation of the bristle assembly. 
     SUMMARY 
     A method of manufacturing a brush seal assembly is disclosed. The method includes circumferentially arranging bristles about an axis. A plate is arranged adjacent to the bristles. Unwelded ends of the bristles are aligned with a periphery of the plate to provide a flush surface across the plate and bristles. The unwelded ends are laser welded to the periphery at the flush surface to provide a unitary subassembly. 
     These and other features of the application 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  is a highly schematic view of an example gas turbine engine. 
         FIG. 2  is a schematic, cross-sectional view of an example brush seal assembly. 
         FIG. 3  is a cross-sectional view of a base and shuttle supporting bristles and a plate. 
         FIG. 4  is a cross-sectional view similar to  FIG. 3  with a cover installed to provide an assembled brush seal fixture. 
         FIG. 5  is a top elevational view of the fixture and shuttle shown in  FIG. 4 . 
         FIG. 6  is a cross-sectional view of the fixture removed from the shuttle. 
         FIG. 7  is an enlarged cross-sectional view of the bristles and plate during welding. 
         FIG. 8  is a schematic view of an example brush seal manufacturing process. 
     
    
    
     DETAILED DESCRIPTION 
     A gas turbine engine  10  is schematically shown in  FIG. 1 . The engine  10  includes a low spool  12  and a high spool  14  coaxial with one another for rotation about a common axis. A low pressure compressor  16  and low pressure turbine  18  are mounted on the low spool  12 . A high pressure compressor section  20  and a high pressure turbine section  22  are mounted on the high spool  14 . A fan  13  is coupled to the low spool  12 . The spools  12 ,  14  and compressor and turbine sections  16 ,  18 ,  20  and  22  are mounted within a case  11 . Various rotating structures are sealed relative to the case  11  with seals  24 . One such commonly used seal is a brush seal. 
     Referring to  FIG. 2 , a brush seal assembly  28  is housed within a carrier  26  and retained relative thereto by a retainer  30  and a shoulder of the carrier. The brush seal assembly  28  seals against a rotating member  32 . The brush seal assembly  28  includes bristles  36  circumferentially arranged about an axis A ( FIG. 5 ). First and second plates  40 ,  42  are secured about the bristles  36  to provide the brush seal assembly  28 . In the example brush seal manufacturing process, the bristles  36  are not secured to one another to provide a bristle assembly or hoop before securing the bristles to the plates  40 ,  42 . Instead, the bristles  36  are secured directly to at least one plate  40 ,  42 . 
     A fixture  44  is used to secure bristles  60  and plate  62  to one another in a desired diametrical and angular orientation so that they can be welded together. Referring to  FIGS. 3-6 , a base  48  is temporarily positioned in a shuttle  46 . The base  48  includes inner guides  54  that provide first bristle alignment features. An inner diameter surface  67  of the shuttle  46  provides a second bristle alignment feature. The shuttle  46  includes outer guides  56  that provide third bristle alignment features. The bristles  60  are supported on a bottom wall  52  of the base  48 . The guides  54 ,  56  locate the bristles  60  in a desired orientation relative to one another as they are circumferentially spaced about the axis A, best shown in  FIG. 5 . 
     Outer ends of the bristles  60  provide an edge  64 . In one example, the edges  64  of the bristles  60  are arranged to abut an inner diameter surface  67  of the shuttle  46 . A plate  62  is arranged adjacent the bristles  60  such that the plate  62  and bristles  64  are in engagement with one another. The plate  62  includes a periphery or perimeter edge  66  that also abuts the inner diameter surface  67  of the shuttle  46 . As a result, the edges  64  of the bristles  60  and the perimeter edge  66  of the plate  62  together provide a flush surface  68 . That is, the outer ends (edges  64 ) of the bristles  60  run true to the outside diameter (perimeter edge  66 ) of the plate  62 . As shown in  FIG. 7 , the edges  64  and perimeter edge  66  are coplanar at a plane P that is tangential to the periphery of the plate  62 . A cover  50  is secured to the base  48  by fasteners  58  to securely retain the bristles  60  and plate  62  relative to one another in the desired position. The fixture  44  is removed from the shuttle  46  using eyebolts  65 , for example. 
     With the fixture  44  removed from the shuttle  46 , the flush surface  68  is exposed, as shown in  FIGS. 6 and 7 . The bristles  60  are welded to the plate  62  using a welder  70 . In one example, the welder  70  is a laser welder that generates a weld bead  72  securing the bristles  60  to the plate  62  with a laser beam  74 . The weld bead  72  generated with the laser welder is more precise and much smaller than a tig generated weld bead, thus requiring less machining. 
     The example brush seal manufacturing method  76  is schematically shown in  FIG. 8 . The method  76  includes aligning the bristles  60  and plate  62  to provide a flush surface  68 , as described above, as schematically indicated at block  78 . The bristles  60  are welded to the plate  62 , as indicated at block  80 . If desired, multiple bristle and plate subassemblies can be arranged one on top of another to provide a multi-layered brush seal, as indicated at block  82 . After welding, the brush seal assembly is machined at its periphery to achieve desired surface features and dimensions at the weld bead  72 , as indicated at block  84 . 
     Although example embodiments have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.