Method and apparatus for reducing the weight critical flexural amplitude of a rotor having anisotropic flexural stiffness

摘要

A method and apparatus quickly and reliably reduce the weight critical flexural amplitude of a flexible rotor having an anisotropic flexural stiffness. Rotor data including the midpoint deflection of a vibration at twice the rotational frequency are measured on the rotating rotor, and a mathematical model is developed, using the measured rotor data, to represent the rotor. Parameters in the dynamic equation of motion in the mathematical model are evaluated in connection with the actual measured data, and thereby the stiffness anisotropy of the rotor is determined by minimizing the difference between the model values and the actual measured values, for example by using the least squares method. Based on the determined anisotropy, compensating data such as machining data for machining the rotor in order to reduce the stiffness anisotropy are calculated. The rotor is machined in accordance with the compensating data, by boring blind holes or continuous through-going holes parallel to the rotational axis and intersecting the soft axis of the rotor. By providing symmetrically arranged pairs of bored holes, the rotational weight balance of the rotor is maintained while the flexural stiffness anisotropy is reduced.