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Self-excited vibrations of rotating discs and shafts with applications to sawing and milling

University of British Columbia

This thesis investigates a number of major self-excited vibrations and instabilities that are involved in the interactions between moving flexible components, such as rotating discs or rotating shafts, and stationary systems, such as work-pieces or constrained systems. These investigations are applicable to a broad range of problems involved in the rotor-stator interactions. As an application, an undesirable lateral self-excited vibration in wood cutting called washboarding is studied theoretically and experimentally. A thorough investigation in selfexcited instabilities due to multiple moving interactions between the saw blade and work-piece such as regenerative cutting force, non-conservative following cutting forces and in-plane asymmetric stress fields are simulated and presented based on a number of new developments in modelling and algorithms. A new theoretical approach for the prediction of chatter in rnilling is also proposed based on a dynamic rnilling model including a rotating spindle. The stability characteristics of this imlling system are investigated by using the generalized Fourier series Method presented in this thesis. A comprehensive experimental study on the self-excited lateral vibration in the wood cutting and washboarding phenomenon was conducted to verify the simulations. A side-cut experiment using the pendulum cutting rig was also conducted in order to support the modelling of regenerative cutting force. To detect the self-excited vibration modes during cutting experimentally, several efficient methods and algorithms of identifying travelling modes, such as the Artificial Damping Method, are also proposed and presented in this thesis.

Thesis/Dissertation

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2009-05-28

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http://hdl.handle.net/2429/8442

Mechanical Engineering

University of British Columbia

UBCV

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