Design, modeling, and motion control of the noncircular turning process for camshaft machining

This paper presents the design, modeling, and motion control of the noncircular turning process for camshaft machining. The cam profile tracking performance requirements are first characterized to meet industry standards. Based on these requirements, a unique test fixture using state-of-the-art actuation and sensing technologies is designed for the noncircular turning process. Modeling of the electrohydraulic servo valve, actuator, and sensors is conducted based on their frequency responses. Digital motion control that achieves asymptotic cam profile tracking while maintaining system robust stability is designed and implemented on the turning test fixture. Spindle speed can be chosen depending on the required profile tracking accuracy with higher speed rendering higher machining rate for rough turning and lower speed rendering higher accuracy for finish turning. Experimental results of turning a variety of cam profiles show that the tracking error is less than 30 μ for spindle speed at 300 rpm and is less than 60 μm for spindle speed at 600 rpm or 1200 rpm.