Self-Directed Control of End Milling

摘要

Self-directed control is a closed-loop control philosophy using qualitativetechniques to achieve real-time generation of a process control cycle. One such instance of self-directed control is Qualitative Process Automation (QPA). This report presents the results of applying QPA to the end milling machining process to maximize feed rates while avoiding the undesirable cutting events of excessive tool deflection, tooth overload and cutter shank overload. QPA is a real-time controller with its control output based on process events and not on temporal relationships as are classical machine tool control systems. Various procedures for detecting machining events with sensor data were investigated and used with QPA to develop a controller for the end milling process. The QPA controller used cutting force, spindle speed and feed rate data to predict and avoid excessive tool and tooth loads and to maintain part tolerance with the highest possible feed rate. Simulation cutting results, using an experimentally validated end milling model showed the QPA system to be successful in controlling and milling cuts for step changes in the radial and axial depths of cut on aluminum workpieces. Experimental cutting results validated the potential of QPA.