This paper presents a process feedback control scheme for cam profile generation by non-circular turning process. While precise tool slide motion can be generated based on real-time servo feedback control, it does not necessarily ensure accurate machined cam profiles. The effects of tool/workpiece geometry, tool wears, machine deformations, and spindle runout error can not be measured by the tool slide displacement sensor and hence are not compensated for by the servo control. A process feedback controller is designed to compensate for the repeatable profile errors from one machining cycle to another. Utilizing the fact that the desired cam profile is periodic over one spindle rotation, process feedback control is analyzed and designed in the frequency domain. Implementation of the process feedback control on a steel camshaft turning demonstrates improvement of the maximum cam profile errors from 80 microns to within 20 microns in five iterations.
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