A study of in-process computer aided evaluation of size and form error for cylindrical workpieces

When the size and the form error of cylindrical workpiece are to be evaluated by in-process computer aided method, a procedure of in-process data conversion from geometrical quantities to digital quantities (G/D) has to be implemented. The paper presents a method of parameter selection for the procedure, which has been successfully used in a computer controlled automotive valve auto-classification machine. A criterion to choose maximum significant harmonic for correct evaluation of form error profile is proposed. The paper also presents a data smoothing approach to reduce the effect of noise when measuring a rotating workpiece so that good measurement accuracy can be achieved. The in-process size evaluation algorithms are also discussed.