Claims
- 1. The method of refurbishing a turbine vane, which includes the steps of welding cracks in the vane surface, slitting portions of the vane at the two ends of the trailing edge to relieve stresses in the vane, welding the trailing edge of the vane to build up the same, welding an elongate surface portion of the vane spaced from and substantially coextensive with the trailing edge to reinforce the vane, welding the slitted portions closed, plasma spraying molten metal or eroded surfaces of the vane to build up the same beyond the original surfaces, and grinding down the built-up surfaces to refinish the same to conform with the original vane surfaces.
CROSS REFERENCES TO RELATED APPLICATIONS
1. Application for United States Letters Patent on METHOD AND MEANS FOR REPAIRING TURBINE VANES in the name of Ralph T. DeMusis, Ser. No. 528,839, filed Dec. 2, 1974, now U.S. Pat. No. 3,988,126.
This invention relates to the recovery of worn turbines vanes, and more particularly to the reworking and resurfacing of worn vanes so as to extend the useful life thereof.
Heretofore turbine vanes as used in aircraft engines, power stations and the like have had a specific useful life, after which they were removed and discarded as being no longer capable of service. Since the initial cost of such vanes is quite considerable, this practice resulted in an appreciable expense that was involved with the maintenance of the turbines. In addition to the loss of use of the equipment involved and the expense of labor in installing new vanes, there was the additional very considerable outlay required for the new replacement parts or vanes which were to be installed. This prior practice, which was necessary to maintain the equipment in reliable operating condition, therefore resulted in high operating charges.
The above disadvantages and drawbacks of prior costly procedures for maintaining turbines and like equipment are in large part obviated by the present invention, which has for its main object the provision of an improved vane refurbishing process and acceptable refurbished vanes in accordance therewith, by which there is considerably reduced the maintenance costs involved with wear and attrition of turbine vanes. A related object of the invention is to provide an improved vane refurbishing process and refurbished vanes for turbines, wherein the resultant product meets rigid requirements of strength and performance, readily acceptable for the fields of service involved. A still futher object of the invention is to provide an improved vane refurbishing process wich is economical to practice, and which produces acceptable refurbished vanes at a relatively low cost.
The above objects are accomplished by a method which first welds closed all cracks, pitted areas and the like, slots end portions of the vane, then builds up by welding the trailing edge of the vane to at least the original dimension, and welds bead reinforcements which are coextensive with and spaced from the trailing edge on both sides of the vane, after which the worn vane surfaces are built-up by a plasma spray process using powdered metal with added silica, which latter burns off during the spraying procedure. The slotting of the vanes prior to appreciable build-up of the surfaces is done to prevent distortion; the slots are welded closed, together with the cooling passages, before the application of the molten plasma-sprayed metal. Finally, the airfoil surfaces are recut to conform to the original contours, and the cooling holes are then cut through as per original specifications.
The slotting to relieve stresses, and lateral reinforcement by positioned welding beads, in conjunction with the welding of all cracks and metal build-up by plasma spraying results in a high quality refurbished product which meets the essential service requirements originally specified for new vanes. The alloy metal which is added to the vanes to build up the worn surfaces conforms to the original metallurgy, by virtue of the use of additional silica to the metal powder used in the plasma spraying, such silica burning off in the plasma stream.
Other features and advantages will hereinafter appear.
US Referenced Citations (7)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 140,341 |
Feb 1951 |
AU |
| 800,414 |
Aug 1958 |
UK |
Patent Grant
4028787
