No abstract

An analytical study of a vibrating bandsaw blade is presented. The blade is modeled as a plate translating over simply-supporting guides. Gyroscopic effects due to the blade’s axial motion as well as in-plane forces resulting from tensioning and the influence of the cutting force are included in the model. The latter is modeled as a nonconservative follower force on the cutting edge of the blade and shown to be destabilizing. A state-space model is developed which includes the effects of time-varying cutting forces and exogenous disturbances. Feedback control via a collocated force actuator/rate sensor is introduced and recent advances in robust control theory are used develop controllers which achieve robust stability and performance with respect to the time-varying model. [S0739-3717(00)01101-6]

A new interpretation of the washboarding phenomenon found in bandsawing of wood is given in this paper. A theoretical model of the washboarding pattern was derived by considering the motion of the teeth during cutting. The theory of machine tool chatter was adapted to illustrate the mechanism of self-induced vibration in bandsawing and to provide a criterion for its existence. It was found that the whole cutting span of the band should be used to determine the vibration characteristics instead of the previous practice of using the section between the workpiece and the top wheel. It has been found that the frequencies responsible for washboarding are all torsional frequencies and physical explanation for this is suggested by considering the squeeze film damping effect of the air gaps between the blade and the sawn surfaces.

No abstract

No abstract