Core positioning in wax pattern die, and associated method and apparatus

Abstract

For forming a shell mould for investment casting, first and second core components are provided. These are formed of ceramic material. The core components are assembled together for manufacturing a wax pattern containing the core component for formation of a shell mould for investment casting. The core components have an arrangement of precursor location features. The method includes machining at least one of the precursor location features to a required shape to provide an arrangement of final location features. The core components are then positioned with respect to each other and/or with respect to a wax pattern die by contacting the arrangement of final location features with corresponding positioning features of a receiving device and/or the wax pattern die.

1 . A method for assembling a core component with respect to a receiving device, the method comprising the steps:
 forming a core component of ceramic material;   providing an arrangement of precursor location features at the surface of the core component;   machining at least one of the precursor location features to a required shape to provide an arrangement of final location features;   positioning the core component with respect to the receiving device by contacting the arrangement of final location features with corresponding positioning features of the receiving device.   
     
     
         2 . A method according to  claim 1  wherein the receiving device comprises a wax pattern die. 
     
     
         3 . A method according to  claim 2  wherein the core component is arranged in the wax pattern die by contacting the arrangement of final location features with corresponding positioning features of the wax pattern die. 
     
     
         4 . A method according to  claim 2  subsequently including the steps of introducing molten wax around the core component in the wax pattern die and allowing the molten wax to solidify to form the wax pattern containing a core component. 
     
     
         5 . A method according to  claim 1  wherein there is provided an arrangement of first and second core components, the first and second core components being positioned relative to each other. 
     
     
         6 . A method according to  claim 5  wherein the receiving device comprises an assembly apparatus for holding the first core component, the method subsequently including the step of configuring the second core component to be assembled relative to the first core component, to provide a core assembly. 
     
     
         7 . A method according to  claim 6  wherein the receiving device further comprises the first core component, the second core component being positioned with respect to the first core component via said final location features. 
     
     
         8 . A method according to  claim 1  wherein the precursor location features are formed by moulding or depositing a material on the surface of the core component. 
     
     
         9 . A method according to  claim 1  wherein the precursor location features are formed integrally with the core component. 
     
     
         10 . A method according to  claim 1  wherein the modification of the precursor location feature is carried out in order to take account of core distortion based on measured data representative of the shape of at least part of the core component. 
     
     
         11 . A method according to  claim 10  wherein the measured data is used to determine the difference in shape between the core component, being an actual core component, and a nominal core component. 
     
     
         12 . A method according to  claim 11  wherein the modification of the precursor location feature is carried out based on the determination of the difference in shape between the actual core component and the nominal core component. 
     
     
         13 . A method according to  claim 11  wherein the measured data is used to determine an optimum assembled position of the first and second core components. 
     
     
         14 . A method according to  claim 11  wherein the measured data is used to determine a best fit of the core components to reduce or minimize a characteristic or function of several characteristics of the cast component. 
     
     
         15 . A method according to  claim 11  wherein a population of first and second core components is provided, the measured data being used to determine one or more matching pairs of first and second core components amongst the population. 
     
     
         16 . A method according to  claim 1  wherein, where the cast component is intended to be an aerofoil component so that the core component has a root region, a tip region and an aerofoil region, the precursor location features are located at one or more of the root region, tip region and aerofoil region. 
     
     
         17 . A method according to  claim 16  wherein the precursor location features are located at the root region and/or the tip region. 
     
     
         18 . An apparatus for assembling a core component with respect to a receiving device, the apparatus comprising:
 a core component of ceramic material; and   a receiving device,   
       wherein the core component has at its surface an arrangement of final location features formed by machining at least one of an arrangement of precursor location features at the surface of the core component to a required shape, the arrangement of final location features being capable of positioning the core component in the receiving device by contacting the arrangement of final location features with corresponding positioning features of the receiving device. 
     
     
         19 . An investment casting process for manufacturing a cast metal component, the process comprising the steps:
 forming a core component of ceramic material;   providing an arrangement of precursor location features at the surface of the core component;   machining at least one of the precursor location features to a required shape to provide an arrangement of final location features;   positioning the core component in a wax pattern die by contacting the arrangement of final location features with corresponding positioning features of the wax pattern die;   introducing molten wax around the core component in the wax pattern die and allowing the molten wax to solidify to form the wax pattern containing a core component;   forming a shell mould around the wax pattern;   removing the wax pattern;   introducing a molten metal into the shell mould to fill space between the shell mould and the core component;   allowing the molten metal to solidify; and   removing the shell mould and the core component.