Ceramic casting core having an integral vane internal core and shroud backside shell for vane segment casting
a ceramic core and inner core technology, applied in the field of monolithic ceramic casting cores, can solve the problems of small features distorted and/or lost, difficult to control the position of ceramic inserts precisely, and small features
Inactive Publication Date: 2015-05-07
SIEMENS AG
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
The invention relates to a method of casting a cooled vane segment for a gas turbine engine. The method involves using a ceramic core to create an internal cooling channel in the airfoil of the vane segment and a separate ceramic shell to define the remaining surface of the vane segment. The small features on the surfaces of the vane segment, such as impingement cooling holes, can be formed by the ceramic core during the casting process. The use of a separate ceramic insert to form the small features on the backside of the vane segment can also be employed, but the position of the insert is difficult to control and the quality of the casting is less than optimal. The invention provides an improved method of casting the cooled vane segment that allows for better control over the small features and improved quality of the casting.
Problems solved by technology
For this reason if the small features are impressed on the surface of the wax pattern and then subject to the dipping process, during which the ceramic shell is formed, the small features are distorted and / or lost.
Since small features in wax patterns cannot survive the dipping process, the surfaces of the vane segment that are defined by the shell, (which are, in turn, defined by the wax pattern), cannot have small features when the small features would result from a wax pattern that is exposed to the dipping process.
However, the position of the ceramic insert is difficult to control precisely and the quality of the casting is less than acceptable when a ceramic insert is used.
Method used
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Embodiment Construction
[0024]The present inventors have devised a unique method and integral casting core through which fine features can be formed on a backside of a shroud of a cooled vane segment when an airfoil portion and the shroud portion (or portions) of the vane segment are simultaneously cast to form a monolithic, cooled, cast vane segment. The fine features may be heat transfer features that can be used in conjunction with impingement cooling jets to more effectively cool the shroud backsides. The method and casting core are enabled in some embodiments through the use of a flexible core die liner. The flexible liner makes it possible to incorporate features into a surface of a casting that are not possible when a rigid core die is used. This is because rigid core dies must be separated along a pull plane. When the die must be pulled apart while sliding along a surface of the casting the two surfaces cannot be shaped such that they interfere with that sliding. Due to the geometry of many parts, ...
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Abstract
A cast ceramic core (110), including: an airfoil portion (116) shaped to define an inner surface (56) of an airfoil (52) of a vane segment (50); and a shell portion (122) having a backside-shaping surface (120) shaped to define a backside surface (68) of a shroud (62) of the vane segment. The backside-shaping surface has a higher elevation (132) and a lower elevation (134). The higher elevation is set apart from a nearest point (138) on the airfoil portion by the lower elevation. The airfoil portion and the shell portion are cast as a monolithic body during a single casting pour.
Description
FIELD OF THE INVENTION[0001]The invention is related to casting of a cooled vane segment used in a gas turbine engine. Specifically, the invention relates to a monolithic ceramic casting core having a conventional core portion used to form an internal cooling channel in the airfoil of the vane segment plus a shroud external shell portion used to form a backside surface of the shroud of the vane segment.BACKGROUND OF THE INVENTION[0002]Industrial gas turbine engine include a compressor for compressing air, a combustor arrangement for combusting a mixture of fuel and the compressed air, and a turbine for extracting energy from the combustion gases. The turbine section includes rows of blades secured to a rotor shaft, all of which are turned by the combustion gases in the energy extraction process. Between the rows of turbine blades are rows of stationary vanes that properly orient the combustion gases as the combustion gases travel within the turbine. Each row of vanes includes vane s...
Claims
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IPC IPC(8): B22C9/24B22C9/10
CPCB22C9/24F01D5/18B22C9/10B22C9/04F01D5/188F01D9/041F05D2260/201B22C7/06
InventorLEE, CHING-PANGHILLIER, GERALD L.UM, JAE Y.AZAD, GM SALAM
OwnerSIEMENS AG