NUMERICAL RESEARCH ON MACHINING STABILITY SUBJECT TO DELAYED PID CONTROL

摘要

Machining stability analysis is important for chatter avoiding and production efficiency improvement. This paper conducts the numerical research on machining stability subject to delayed PID active control which is used to avoid chatter in machine milling. This control strategy is introduced into a two-degree-of-freedom milling system for illustration, the resulting hybrid system with both regenerative and feedback delays is represented as a delay-differential equation with time-periodic coefficients. From the comparison of stability region, it is found that the delayed PID control with proper parameters can lift the stability boundary largely compared with the case without control. To evaluate the stabilizability of the controlled system in cutting, the sensitivity of the stability boundary with respect to the PID parameters is analyzed. The numerical simulation of critical axial depth to PID parameters indicate that the milling stability critical boundary varies drastically with the derivative parameter. It also demonstrates that the stability critical boundary is strongly influenced by the proportional parameter, but it is less effected by the integral parameter. Hence, the stability domain can be expanded drastically with appropriate PID parameters based on the analysis above.