Dynamic model for the determination of instability of periodic circular cutting of wood tissue

Shown is a dynamic model of periodic circular cutting of oriented wood tissue in which both the properties of the material and the dynamic properties of the machining system have been considered. The cutting or exciting force is the result of internal and external modulation. The internal modulation is the result of the effect of the properties of the machined material which are given by specific cutting pressure k(s), while the external modulation is the consequence of the varying material flux which is affected by relative displacements between the workpiece and the tool. Relative displcements, which are the consequence of the manner of excitation and dynamic properties of the machining system, are also the cause of self-excitation occurrence. As in the process of cutting, the cutting or self-exciting force depends on relative displacements between the tool and the workpiece, the dynamic model developed is non-linear. By simulation of a dynamic model it is possible to analyse the process of cutting wood tissue in its entirety, and it can thus be employed to optimize the selection of tools and the processing parameters of machining.