Patent Publication Number: US-6666653-B1

Title: Inertia welding of blades to rotors

Description:
BACKGROUND OF THE INVENTION 
     FIELD OF THE INVENTION 
     The present invention relates generally to construction of gas turbine engine integrally bladed rotors and, more specifically, to inertia welding of blades to gas turbine engine rotors. 
     Fan, compressor and other gas turbine engine rotors may have a BLISK or a BLUM. BLISKS have blades that are integral with a disk and BLUMS have blades that are integral with a drum. Conventionally, BLISKS and BLUMS are made by machining an airfoil shape (using conventional machining or ECM/EDM processes) from a forged disk. Linear and angularly reciprocating friction welding methods have been under development for manufacturing BLISKS and BLUMS for gas turbine engine rotors. Angularly reciprocating friction welding includes the disc or drum rotor being angularly reciprocated while the airfoils or blades are pressed radially against the disk or rotor circumference. Linear reciprocating friction welding includes linear reciprocating airfoils or the blades as they are pressed radially against the disk or rotor circumference. 
     In friction welding, the disk is clamped, a blade is clamped in a reciprocating head of a machine, and the blade is rubbed against a surface of the disk in a reciprocating motion to generate frictional heat at an interface between the disk and the blade. When a predetermined loss of length is achieved, the blade is brought suddenly to a halt at a precisely defined location on the disk and is pressed against the disk for a short time to create the weld. When the blade and disk assembly has cooled flash at the interface is removed and any required machining operations are carried out. 
     One drawback to using BLISKS and BLUMS is the high manufacturing cost. The manufacturing processes described above are expensive and complex to perform on airfoil shapes, particularly, the complex shapes used today and being developed for future use. Additionally, the disk material and the airfoil material must meet different design requirements. Machining the blisk from one piece often requires compromises in the part design or material selection. 
     BRIEF DESCRIPTION OF THE INVENTION 
     A method for manufacturing an integrally bladed rotor includes fixturing a plurality of blade blanks having radially inwardly facing blade conical surfaces in a segmented blade ring assembly circumscribed around an axis. A rotor ring is rotated to a contact speed. The rotor ring has a radially outwardly facing ring conical surface circumscribed around the axis and mates to the blade conical surfaces. The rotor ring and the segmented blade ring assembly are frictionally engaged under an axially applied weld load to effect a conical inertia weld therebetween along the mating blade conical surfaces and ring conical surface. In one embodiment, each of the blade blanks includes an airfoil portion extending radially outwardly from an annular base portion and the base portion includes the mating blade conical surfaces. The base portion includes a radially outer conical surface parallel to the blade conical surface and the conical inertia weld passes through the airfoil portion. Completed airfoils and radially outer flowpath surface are formed by machining excess stock from the base portion and the rotor ring after the welding. Materials of the blade blanks and the rotor ring may be two different alloys. 
     In another embodiment, each of the blade blanks includes a rim portion of the integrally bladed rotor and the conical inertia weld is between the rim portions and a conical rotor ring. Holes may be machined in an annular region of the rim. The holes may be circumferentially evenly distributed within the annular region and centered along radii passing through interfaces the blade blanks. 
     The invention includes the integrally bladed rotor and the airfoils circumferentially distributed about and integral with the rim. The airfoils extend radially outwardly from respective airfoil bases on a radially outer flowpath surface of the rim to airfoil tips. A conical inertia weld is located between the airfoil tips and a radially inwardly facing rim surface of the rim. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic cross-sectional view illustration of a portion of an exemplary gas turbine engine compressor integrally bladed rotor including a rim and a conical weld. 
     FIG. 2 is a side elevational view illustration of a blade blank to be inertia welded to a rotor ring to form the integrally bladed rotor illustrated in FIG.  1 . 
     FIG. 3 is a radially inwardly looking elevational view illustration of the blade blank in illustrated FIG.  1 . 
     FIG. 4 is an aft looking forward side elevational view illustration of the blade blank illustrated in FIG.  1 . 
     FIG. 5 is an aft looking forward elevational view illustration of a sector of a segmented blade ring assembly of the blade blanks arranged to be inertia welded to form the integrally bladed rotor illustrated in FIG.  1 . 
     FIG. 6 is a cross-sectional view illustration of one of the blade blanks of the segmented blade ring assembly being inertia welded to form the integrally bladed rotor illustrated in FIG.  1 . 
     FIG. 7 is a side elevational view illustration of an alternative blade blank to be inertia welded to an alternative rotor ring to form an alternative integrally bladed rotor illustrated in FIG.  10 . 
     FIG. 8 is an aft looking forward elevational view illustration of a sector of an alternative segmented blade ring assembly to be welded to the alternative blade blanks illustrated in FIG.  7 . 
     FIG. 9 is a cross-sectional view illustration of one of alternative the blade blanks being inertia welded to the segmented blade ring assembly to form the alternative integrally bladed rotor illustrated in FIG.  10 . 
     FIG. 10 is a cross-sectional view illustration of the alternative integrally bladed rotor made by inertia welding the alternative blade blanks to the segmented blade ring assembly. 
     FIG. 11 is a cross-sectional view illustration of the alternative integrally bladed rotor in FIG. 10 after post welding machining. 
     FIG. 12 is a schematic cross-sectional view illustration of the alternative gas turbine engine compressor integrally bladed rotor in FIG. 11 with holes through the rim of the rotor. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Illustrated in FIG. 1 is a portion of gas turbine engine integrally bladed rotor  10 . The portion may be from a fan or compressor and may be part of a BLISK or a BLUM. BLISKS have blades that are integral with a disk and BLUMS have blades that are integral with a drum. The integrally bladed rotor  10  includes a hub  80 , a web  82  extending radially outwardly from the hub to an annular rim  59  and circumscribed around an axis  22 . A plurality of airfoils  52  extend radially outwardly from, are circumferentially disposed about, and integral with the rim  59 . The airfoils  52  extend radially outwardly from respective airfoil bases  57  on a radially outer flowpath surface  44  of platforms  47  formed in the rim  59  to airfoil tips  61 . Forward and aft axial extensions  71  and  73  may be arms of a disk or annular rotor sections of a drum. The airfoils  52  include radially inner and outer sections  63 ,  65  bonded together along a conical inertia weld  30  radially located between the bases  57  and the tips  61 . The inertia weld  30  is generally located between the tips  61  and a radially inwardly facing rim surface  60  of said rim  59 . The airfoils  52  and the rim  59  may be made from two different alloys. 
     The integrally bladed rotor  10  is manufactured in part by fixturing a plurality of blade blanks  14  into a segmented blade ring assembly  20 , illustrated in FIG. 5, circumscribed around the axis  22  as illustrated in FIG.  6 . Rotation is effected between a rotor ring  24  and the blade ring assembly  20  such as by rotating the rotor ring  24  to contact speed for inertia welding as illustrated in FIG.  6 . The rotor ring and the segmented blade ring assembly  20  are frictionally engaged under an axially applied weld load  29  to effect the conical inertia weld  30  therebetween and along mating blade conical surfaces  18  of the blade blanks  14  and a ring conical surface  28  of the rotor ring  24 . 
     Referring to FIGS. 2,  3 , and  4 , each one of the blade blanks  14  has an airfoil portion  32  extending radially outwardly from an annular base portion  34 . The base portion  34  includes the radially inwardly facing blade conical surfaces  18  and a radially outer conical surface  36  parallel to the blade conical surface  18 . The conical inertia weld  30 , illustrated in FIG. 1, is effected between the annular base portions  34  and the rotor ring  24 . The completed airfoils  52 , the platforms  47  formed in the rim  59 , and the radially outer flowpath surface  44  are formed by machining excess stock  38  from the base portion  34  and the rotor ring  24  after the welding as illustrated in FIG.  1 . Final shapes of the airfoils  52  are machined after welding from the radially inner and outer sections  63 ,  65 . Materials of the blade blanks  14  and the rotor ring  24  may be two different alloys. 
     Illustrated in FIGS. 7,  8  , and  9  is an alternative embodiment of the blade blanks  14 , each of which includes a rim portion  39  used to form the rim  59  of the integrally bladed rotor  10 . The conical inertia weld  30  is formed between and bonds the rim portions  39  and a conical rotor ring  124 . The blade conical surfaces  18  are located on the rim portions  39  of the blade blanks  14 . The airfoils  52  and the rim  59  may be made from two different alloys. The integrally bladed rotor  10  is manufactured in part by fixturing the plurality of the blade blanks  14 , illustrated in FIG. 8, into the segmented blade ring assembly  20  circumscribed around the axis  22  as illustrated in FIG.  8 . Rotation is effected between the conical rotor ring  124  and the blade ring assembly  20  such as by rotating the conical rotor ring  124  to contact speed for inertia welding as illustrated in FIG.  9 . The conical rotor ring  124  and the segmented blade ring assembly  20  are frictionally engaged under an axially applied weld load  29  to effect a conical inertia weld  30  therebetween and along mating blade conical surfaces  18  of the blade blanks  14  and a ring conical surface  28  of the conical rotor ring  124  as illustrated in FIG.  10 . 
     Illustrated in FIG. 11 are the completed airfoils  52 , the platforms  47  formed in the rim  59 , and the radially outer flowpath surface  44  are formed by machining the excess stock  38  from the rim portion  39  base and the conical rotor ring  124  after the welding. The rim  59  is formed from the rim portions  39  of the blade blanks  14  and the conical rotor ring  124 . The airfoils  52  extend radially outwardly of and are formed integral with a radially outer annular portion  62  of the rim  59 . The radially outer annular portion  62  has a radially inwardly facing conical boundary  64  and is formed from the rim portions  39  of the blade blanks  14 . A radially inner portion  66  of the rim  59  is machined from the conical rotor ring  124  and has a radially outwardly facing conical boundary  68 . The conical inertia weld  30  is disposed between the radially inner and outer annular portions  66 , 62  of the rim  59  along the radially inwardly and outwardly facing conical boundaries  64 ,  68 . 
     Holes  48  may be machined in an annular region  50  of the rim  59  after the welding. The holes  48  may be circumferentially evenly distributed within the annular region  50  and centered along radii  56  passing through interfaces  58  between segments  70  of the outer annular portion  62  of the rim  59  formed by the blade blanks  14 . The annular region  50  is located in the welded together rim portions  39  and the conical rotor ring  124 . 
     While there have been described herein what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein and, it is therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention. Accordingly, what is desired to be secured by Letters Patent of the United States is the invention as defined and differentiated in the following claims.