Patent Abstract:
A method of forming a complex shaped part includes the steps of forming a polymer core by an additive manufacturing process. A metal is plated about surfaces of the polymer core, and the polymer core is removed, leaving hollows within a plate core. Metal powder is deposited within the hollows. An integral blade rotor is also disclosed.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/706,839 filed Sep. 28, 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This application relates to a method of making very complex shaped components in a manner that is reliable and simplified compared to the prior art. 
         [0003]    Modern technology is called upon to make increasingly complex shaped components. As one example, gas turbine engines are often provided with an integrally bladed rotor. An integrally bladed rotor includes a hollow hub with a plurality of complex airfoil shapes extending radially outwardly of the hub. 
         [0004]    Currently, integrally bladed rotors are often manufactured using hot forging technologies and then other technologies, such as milling, super abrasive machining, electro-chemical machining or other types of machining. 
         [0005]    In addition, joining technologies, such as linear friction welding, may be utilized to secure the airfoils to the hub. 
         [0006]    All of these processes are expensive and raise various challenges. 
         [0007]    In addition, laser powder deposition has been utilized for deposing material on outer surfaces of the integrally bladed rotor. However, these techniques have not always provided an acceptable finished component. 
       SUMMARY 
       [0008]    In a featured embodiment, a method of forming a complex shaped part includes the steps of forming a polymer core by an additive manufacturing process, plating a metal about surfaces of the polymer core, removing the polymer core leaving hollows within a plating core, and depositing metal powder within the hollows. 
         [0009]    In another embodiment according to the previous embodiment, a consolidation step occurs after the depositing of the metal powder into the hollows. 
         [0010]    In another embodiment according to any of the previous embodiments, the consolidation process is a hot isostatic pressurization process. 
         [0011]    In another embodiment according to any of the previous embodiments, the plating metal is a nickel based material. 
         [0012]    In another embodiment according to any of the previous embodiments, the metal powder is also a nickel based material. 
         [0013]    In another embodiment according to any of the previous embodiments, the complex shaped component is an integrally bladed rotor. The integrally bladed rotor has a hub and radially outwardly extending airfoils with the hollows that are formed in both the hub and the airfoils. 
         [0014]    In another embodiment according to any of the previous embodiments, the plating occurs utilizing electroplating. 
         [0015]    In another embodiment according to any of the previous embodiments, the polymer core is removed in a furnace. 
         [0016]    In another embodiment according to any of the previous embodiments, the polymer core is melted, disintegrated or evaporated in the furnace. 
         [0017]    In another embodiment according to any of the previous embodiments, the additive manufacturing process includes one of selective lithography analysis, selective laser sintering, fusion deposition of material or laminated object manufacturing. 
         [0018]    In another embodiment according to any of the previous embodiments, a computer model of the complex shaped component is utilized to control the additive manufacturing process to form the polymer core. 
         [0019]    In another embodiment according to any of the previous embodiments, dimensions of the polymer core are selected to be slightly smaller than dimensions of a desired final complex shaped part. 
         [0020]    In another featured embodiment, an integrally bladed rotor has a hub with an inner bore and an outer surface. A plurality of airfoils extend radially outwardly of the outer surface. The airfoils and hub have radially outer surfaces and axially outer surfaces formed of a relatively thin metal plate layer. There is metal powder within hollows defined axially and radially inwardly of the plate layer. 
         [0021]    In another embodiment according to the previous embodiment, the plate layer is a nickel based material. 
         [0022]    In another embodiment according to any of the previous embodiments, the metal powder is a nickel based material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  illustrates an integrally bladed rotor. 
           [0024]      FIG. 2A  schematically illustrates an example additive manufacturing machine, and further shows a first step in forming the integrally bladed rotor. 
           [0025]      FIG. 2B  shows an intermediate step. 
           [0026]      FIG. 2C  shows another intermediate step. 
           [0027]      FIG. 2D  shows yet another intermediate step. 
           [0028]      FIG. 2E  shows yet another intermediate step. 
           [0029]      FIG. 2F  shows yet another manufacturing step. 
           [0030]      FIG. 2G  shows yet another step. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    An integrally bladed rotor  20  is illustrated in  FIG. 1 . As known, a hub  22  has an outer surface  24 , and a plurality of airfoils  26  extend radially outwardly of the outer surface  24 . The integrally bladed rotor  20  has a very complex shape and raises challenges to manufacture. 
         [0032]    This application is directed to a method of making such an integrally bladed rotor in a reliable and relatively simple manner compared to the prior art. While an integrally bladed rotor is specifically disclosed, any number of other complex shaped parts will benefit from the teachings of this application. 
         [0033]      FIG. 2A  shows an initial step. A core  120  for forming an integrally bladed rotor is illustrated being only partially formed. A rapid prototyping process which utilizes additive manufacturing techniques is preferably utilized to form the core  120  from an appropriate polymer. A system  30  is shown schematically forming the core  120  from a polymer in such a rapid manufacturing process. Examples of such additive manufacturing processes include stereolithography (SLA), selective laser sintering, fused deposition modeling, laminated object manufacturing, or any other rapid manufacturing. As known, core  120  is being built up from layers. A CAD model of the desired integrally bladed rotor  20  can be utilized to drive these processes. 
         [0034]      FIG. 2B  shows the final core  220 . Core  220  is manufactured to be of the general exact shape of the final integrally bladed rotor  20  and has outer surface  224 , inner surface  222 , and airfoils  226 . 
         [0035]      FIG. 2C  shows a subsequent step. A plating process (shown schematically at  34 ) is utilized to plate an appropriate metal for forming the integrally bladed rotor onto a polymer. The process deposits a plating  326 ,  328  and  329  on the core  220 . In fact,  FIG. 2C  is an oversimplification, in that the plating  328  would typically only be found in the portions of the outer surface  224  intermediate blades  226  on the core. Further, while a blade  226  is illustrated in  FIG. 2C , in fact, the area  327  would also receive the plating to form a lateral outer wall of the airfoils for the final integrally bladed rotor. The thickness of the plating may be exaggerated to show the plating layers. However, the purpose of  FIG. 2C  is to make clear that the plating would cover the core  220 , and that there would be plated metal on outer surfaces of the core  220  after the step  2 C. 
         [0036]    One metal which may be plated is an appropriate nickel or nickel alloy for forming the integrally bladed rotor  20 . One possible process  34  would be electroplating. The plating thickness should be controlled and selected to achieve a structurally sound configuration after the step  2 D. 
         [0037]    In step  2 E, hollows are illustrated at areas  500  and  501 . To reach step  2 E, the core  120  has been removed, as shown in  FIG. 2D . In one example, the combined core and plating, as shown at  601 , may be placed in a furnace  600  as shown schematically in  FIG. 2D . The polymer forming the core  220  may be melted, disintegrated, or evaporated in any known manner. 
         [0038]    What is left is a hollow configuration  320  as shown in  FIG. 2E . A hollow structure  320  incorporates plating portions  326 ,  327 ,  328  and  329 . Within this hollow structure  320  are hollows  500  within each of the airfoils and hollows  501  within the portions  328  and between the sides  329 . 
         [0039]      FIG. 2F  shows a subsequent step. A metal powder fills the hollows. The metal powder is shown at  400  and  401 , and may be deposited within the hollows in any known manner. A tool  610  is illustrated schematically delivering the metal powder into the hollows. The metal powder may be a nickel based powder that may be similar to the plating material. To ensure that powder fills in all areas of a hollow plated shell with complex shape configuration, a feeder spruce system may be included. 
         [0040]    After step  2 F, an integrally bladed rotor  520  may be subjected to some finishing operation. As an example, a hot isostatic pressure operation  601  is illustrated in  FIG. 2G  and provides very high pressure to the integrally bladed rotor  520 . As known, in the operation  601 , a container is typically filled with a fluid, and the fluid is pressurized to, in turn, pressurize the enclosed part  520 . Powder out gassing may be utilized prior to the hot isostatic pressure operation. 
         [0041]    Other finishing techniques, such as quasi-isostatic pressing or dynamic compaction can be utilized in place of the hot isostatic pressure. 
         [0042]    A worker on this art may recognize that the CAD model initially utilized to form the core at step  2 A may be adjusted to account for material shrinkage which might occur due to the consolidation operation. 
         [0043]    An integrally bladed rotor  520  has a hub with an inner bore  54  and an outer surface  522 , and a plurality of airfoils  523  extending outwardly of the outer surface. The airfoils  523  and hub have radially outer surfaces and axially outer surfaces formed of a relatively thin metal plate layer. There is metal powder within hollows defined axially and radially inwardly of the plated layer. 
         [0044]    The plate layer may be a nickel based material, and the metal powder may be a nickel based material. 
         [0045]    Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Technology Classification (CPC): 2