Effect of Tool-Operating Mode on Circularity Deviation in Multilobed Turbine Rotor Journal Restoration with Location on Bearing Bottom Half
A progressive method of a worn turbine rotor journal restoration is machining on mounting bearing of turbine plant directly. Grinding head machines rotor journal moving to its axis while the restored journal in its rotation is located on the bearing bottom half. Thus, rotor center position keeps changing, thus, a required circularity accuracy is not achieved. The best law of grinding head radial feed speed variation is one of the methods providing machining accuracy increase. The effect of feed variation on machined surface circularity accuracy for various numbers of worn rotor journal cross section lobes is investigated. The generation of geometry computer modeling using voxel approach has detected that feed variation practically has no effect on circularity accuracy if lobes number is even. However, for the machining of rotor journals with a three-lobed radial section, the sine variation of the radial tool feed is efficient. Machining accuracy has been increased by 20% compared to the case of machining at constant feed. In all cases, using the same number of workpiece spark-out revolutions as the number of workpiece revolutions at constant tool radial feed has an essential effect on circularity accuracy.
KeywordsTurbine restoration Rotor journal Location on journal Location on bearing Centerless grinding Circularity deviation Voxel modeling
The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0011.
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