The Dynamic Interaction of the Cutting Process, Workpiece, and Lathe's Structure in Facing

摘要

The effects on the onset of chatter by the dynamic interaction of the workpiece and its method of support, the turret, the lathe bed, the cutting forces and the cutting conditions are determined, A generalized modal analysis is used to solve the four governing equations in the frequency domain. It is found that there are four dimensionless quantities that couple the equations, the most important being NB, the ratio of the static stiffness of the workpiece to the translational stiffness of the turret. The dimensionless critical depth of cut Hc and corresponding chatter frequency coefficient Q2C are determined as a function ofN0for two feed rates, several surface speeds, and for two workpiece boundary conditions; cantilevered and clamped-hinged. It is shown that the magnitudes of Hc and fl2c are oscillatory as a function of No, and the occurrence of their peak values is proportional to the surface speed of the workpiece to the fourth power. It is found that for the parameters selected the effect of the dynamic response of the lathe bed is to increase by 7 percent the values of No at which the peak values of Hc occur. It is also found that the value of the equivalent viscous damping of the system and the magnitude of the real part of the cutting force coefficient govern the magnitudes ofHc and Ql as a function of N_0.