Force Sensorless Control of Cutting Resistance for NC Machine Tools by Spindle Motor Control Using Variable Pulse Number T-method

摘要

This paper proposes a force sensorless control of cutting resistance for numerical control (NC) machine tools by spindle motor. In conventional NC machine tools, speed of spindle motor is set to a constant value during machining, and the spindle speed is determined according to operator's experience. The proposed method estimates cutting resistance by disturbance observer, and the spindle speed is determined by controlling the cutting resistance to follow the reference value. In addition, a novel method for velocity calculation which is referred as variable pulse number T-method is proposed to reduce the velocity measurement noise and to improve the robustness of disturbance observer.