David John Gandy

US Patent:

61451940, Nov 14, 2000

Filed:

May 28, 1999

Appl. No.:

9/321703

Inventors:

Ronald E. Munson - Round Rock TX
Shane Joseph Findlan - Harrisburg NC
David W. Gandy - Concord NC
Ramaswamy Viswanathan - Saratoga CA

Assignee:

Electric Power Research Institute, Inc. - Palo Alto CA

International Classification:

B23P 1500

US Classification:

298891

Abstract:

A method for repairing a shrink-fitted turbine disc without removing the disc from the shaft. The method is composed of two basic steps: (1) depositing one or more weld layers in a vicinity of a defective region of the disc using a temperbead welding process and (2) heat treating the disc using an induction heating process. In a first embodiment of the method, the heat treating step includes heating a heat-affected zone of the disc in a vicinity of the one or more weld layers to a temperature T. sub. h, heating a rim region of the disc to a temperature T. sub. r and heating a bore region of the disc to a temperature T. sub. b, where T. sub. h, T. sub. r >T. sub. b. In a second embodiment of the method, the heat treating step includes heating a region of the disc in a vicinity of the one or more weld layers using the induction heating process and concurrently cooling a bore region of the disc. In a third embodiment of the method, the heat treating step includes heating at least a portion of the disc using the induction heating process and concurrently heating the shaft to maintain a predetermined temperature differential between the bore region of the disc and the shaft. In a fourth embodiment of the method, the heat treating step includes heating at least a portion of the disc using the induction heating process and concurrently heating the shaft to maintain a uniform temperature between the bore region of the disc and the shaft.