Coated bucket damper pin

• US 20060257262A1
• Filed: 05/12/2005
• Published: 11/16/2006
• Est. Priority Date: 05/12/2005
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Feng, Ganjiang, Itzel, Gary Michael, Jacala, Ariel Caesar-Prepena, Morey, Kathleen B., Bucci, David V., Lewis, Doyle C.
• Granted Patent: US 7,367,123 B2
• Time in Patent Office: Days
• US Class Current: 416/248
• CPC Class Codes: F01D 5/22 Blade-to-blade connections, e.g. for damping vibrations
• CPC Class Codes: F01D 5/26 Antivibration means not restricted to blade form or construction or to blade-to-blade connections or to the use of particular materials
• CPC Class Codes: F05D 2230/311 by torch or flame spraying
• CPC Class Codes: F05D 2230/312 by plasma spraying
• CPC Class Codes: F05D 2230/90 Coating; Surface treatment
• CPC Class Codes: F05D 2250/141 circular
• CPC Class Codes: F05D 2300/611 Coating
• CPC Class Codes: Y10S 416/50 Vibration damping features
• CPC Class Codes: Y10T 29/4932 Turbomachine making

Abstract

A damper pin for a turbine bucket includes an elongated main body portion of substantially uniform cross-sectional shape having opposite ends, one only of said opposite ends coated with a corrosion and oxidation-resistant coating.

Claims

1. A damper pin for a turbine bucket comprising an elongated main body portion of substantially uniform cross-sectional shape having opposite ends, one only of said opposite ends coated with a corrosion and oxidation-resistant coating.

2. The damper pin of claim 1 wherein said elongated main body portion is a cobalt alloy.

3. The damper, pin of claim 1 wherein said coating is an MCrAlY composition where M is iron, cobalt and/or nickel.

4. The damper pin of claim 2 wherein said coating is an MCrAlY composition where M is iron, cobalt and/or nickel.

5. The damper pin of claim 1 wherein said substantially uniform cross-sectional shape is circular.

6. The damper pin of claim 5 wherein said one of said opposite ends has a reduced cross-sectional shape that is not circular.

7. The damper pin of claim 6 wherein said reduced cross-sectional shape is semi-circular.

8. The damper pin of claim 1 wherein said one of said opposite ends is first machined over its entirety to a lesser dimension such that when coated, said one end has a cross-sectional shape and area substantially identical to said one end before being machined.

14. The damper pin of claim 8 wherein said leading end has a semi-circular cross-sectional shape.

9. A turbine rotor wheel comprising a plurality of circumferentially arranged buckets, each adjacent pair of buckets having a damper pin inserted therebetween, said damper pin comprising an elongated main body portion of substantially uniform cross-sectional shape having opposite leading and trailing ends of different cross-sectional shape than said main body portion, only said leading end coated with a corrosion and oxidation-resistant coating.

10. The damper pin of claim 9 wherein said elongated main body portion is a cobalt alloy.

11. The damper pin of claim 9 wherein said coating is an MCrAlY composition where M is iron, cobalt and/or nickel.

12. The damper pin of claim 10 wherein said coating is an MCrAlY composition where M is iron, cobalt and/or nickel.

13. The damper pin of claim 9 wherein said substantially uniform cross-sectional shape is circular.

15. The damper pin of claim 10 wherein said leading end is first machined over its entirety to a lesser dimension such that when coated, said one end has a cross-sectional shape and area substantially identical to said one end before being machined.

16. A method of reducing corrosion and oxidation at a leading end of a damper pin located between adjacent buckets on a steam turbine rotor wheel comprising:

(a) machining said leading end to reduce a cross-sectional area of said leading end; and

(b) applying a corrosion and oxidation-resistant coating to only said one end to a thickness such that said one end has a cross-sectional shape and area substantially equal to said leading end prior to step (a).

17. The method of claim 16 wherein said damper pin is composed of a cobalt alloy.

18. The method of claim 17 wherein said coating is an MCrAlY composition where M is iron, cobalt and/or nickel.

19. The method of claim 17 wherein said damper pin has a substantially uniform circular cross-sectional shape over an elongated main body portion between two ends, said two ends having a different cross-sectional shape.

20. The method of claim 16 wherein said different cross-sectional shape is semi-circular.