REFRACTORY METAL CORE INTEGRALLY CAST EXIT TRENCH
A refractory metal core for use in casting a turbine engine part has a main portion and a plurality of tabs extending from the main portion. An end portion having a first edge which joins together the plurality of tabs and a second edge, opposed to the first edge, located internally of an exterior boundary of the cast part may be provided.
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The Government of the United States of America may have rights in the present invention as a result of Contract No. F333615-03-D-2354-0009 awarded by the Department of the Air Force.
BACKGROUNDThe present disclosure relates to a refractory metal core having separate exit tabs which are ganged together within the exterior boundary of a finished cast part and to a turbine engine part formed using the refractory metal core.
Refractory metal cores have been used to form cooling passages in turbine engine components such as blades and vanes. The main portion of the refractory metal core may be configured to create a cooling air passage internal to the component. Small tabs extending from the refractory metal core are used to form exit holes associated with the cooling air passage. These individual exit tabs are sometimes connected together outside the envelope of the finished casting to improve the casting process.
The exit holes formed in this manner can restrict the types of coatings that can be subsequently applied or significantly increase the cost of forming the coatings since very thick coatings will cover the holes. In addition, the cast holes are subject to occasional partial clogging or bending over of edges from handling or contamination, leading to an undesirable decrease in passage cooling flow.
SUMMARY OF THE INVENTIONThe present disclosure relates to a refractory metal core for use in casting turbine engine part. The refractory metal core broadly comprises a main portion, a plurality of tabs extending from said main portion, and an end portion which at one end joins together some or all of said plurality of tabs. The end portion has an opposite edge located prior to an exterior boundary of the part.
The present disclosure also relates to a turbine engine part having an airfoil portion with a cooling passage formed therein or a part without an airfoil portion which forms the inner or outer gaspath endwalls. The cooling passage has a plurality of exit holes and an exit trench which receives cooling fluid from said exit holes.
Other details of the refractory metal core integrally cast exit trench, as well as advantages attendant thereto, are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.
As shown in
To alleviate the foregoing issues, the refractory metal core 10′ of
The main portion 16′, the tabs 18′, and the piece 22′ may be integrally formed from a refractory metal material such as molybdenum or a molybdenum alloy.
The exit trench 106 protects the exit holes 104 from external contamination and handling damage by keeping the terminus of each exit hole 104 inboard of the exterior boundary or edge 14′ of the cast part. The exit trench 106 creates enough flow area to be much more tolerant of any contaminant buildup in the corners of the opening 26′ of the exit trench 106 than individual holes such as those created by the refractory metal core of
To form the cast part 12′, the refractory metal core 10′ is placed into a mold or die. After the part 12′ has been formed from a molten metal material, the refractory metal core 10′ may be removed using any suitable leaching technique known in the art. After the refractory metal core 10′ is removed, as shown in
The exit trench 106 has at least one slot 112 through which cooling fluid is discharged over an exterior section of part 100.
Turbine engine components which could take advantage of the geometry created by the refractory metal core of
It is advantageous to cast cooled turbine gaspath hardware with complete cooling passages including exit holes. The integral cast exit holes result in reduced cost due to the elimination of machining operations and provide support to the small cores used for local or in-wall cooling passages.
In accordance with the present disclosure, there has been described an integral cast cooling flow exit trench. While the integral cast cooling flow exit trench has been described in the context of specific embodiments thereof, other unforeseeable alternatives, modifications and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations as fall within the broad scope of the appended claims.
Claims
1. A refractory metal core for use in casting a turbine engine part which comprises a main portion, a plurality of tabs extending from said main portion, and an end portion having a first edge which joins together said plurality of tabs and a second edge, opposed to the first edge, located internally of an exterior boundary of the cast part.
2. The refractory metal core of claim 1, wherein said main portion is configured to form at least one cooling passage in said cast part.
3. The refractory metal core of claim 2, wherein said plurality of tabs are configured to form a plurality of exit holes which cooperate with said at least one cooling passage.
4. The refractory metal core of claim 3, wherein said end portion is configured to form an exit trench in said cast part.
5. The refractory metal core of claim 1, wherein said main portion, said plurality of tabs, and said end portion are integrally formed.
6. The refractory metal core of claim 1, wherein said main portion, said plurality of tabs, and said end portion are formed from a material selected from the group of molybdenum and a molybdenum alloy.
7. A turbine engine part comprising at least one internal cooling passage, a plurality of exit holes connected to said at least one cooling passage for receiving a cooling fluid, and an exit trench for receiving said cooling fluid from said exit holes.
8. The turbine engine part according to claim 7, wherein said exit holes have a terminal end spaced from an exterior boundary of the part.
9. The turbine engine part of claim 8, further comprising said trench being located between said terminal end of said exit holes and said exterior boundary.
10. The turbine engine part of claim 7, wherein said exit trench has at least one slot associated therewith through which said cooling fluid is discharged over an exterior surface of said turbine engine part.
11. A refractory metal core for use in casting a turbine engine part which comprises a main portion, a plurality of arms extending from said main portion, and a plurality of hammerhead tabs attached to said arms.
12. The refractory metal core of claim 11, wherein said main portion is configured to form at least one cooling passage in said cast part.
13. The refractory metal core of claim 11, wherein said main portion, said arms, and said tabs are integrally formed.
14. The refractory metal core of claim 11, wherein said main portion, said arms, and said tabs are formed from a refractory metal or metal alloy.
Type: Application
Filed: Jul 27, 2009
Publication Date: Jan 27, 2011
Applicant: UNITED TECHNOLOGIES CORPORATION (Hartford, CT)
Inventor: Eric A. Hudson (Harwinton, CT)
Application Number: 12/509,608
International Classification: F01D 5/08 (20060101); B22D 15/00 (20060101);