Detection of Tool Wear using Characteristic Values of Dynamic Cutting Process: 2nd Report, Adaptability of Characteristic Values to Variation of Measurement Conditions

In-process measurement of tool flank wear is very important for judgment of tool life with the object of running fully automated machine tools economically. The purpose of this study is to propose a new method of detecting tool flank wear by using characteristic values of dynamic cutting process during steady-state cutting in turning operation. In this report, a simple calculation model of dynamic thrust force was proposed to derive equations of characteristic values from it, and effectiveness of the equations was experimentally verified under many cutting conditions and excitation conditions of a workpiece system. As a result of the calculations and the experiments, we reached conclusions that two characteristic values of dynamic cutting process, standard deviation of dynamic thrust force normalized by the standard deviation of workpiece vibration displacement and coefficient of correlation between dynamic thrust force and vibration displacement, have the following properties. (i) The characteristic values remained almost constant with variation of feed rate of a cutting tool and vibration amplitude of a workpiece. (ii) On condition that vibration frequency of a workpiece is constant, the characteristic values obtained under different cutting speeds can be standardized by normalizing the width of flank wear to the cutting speed. (iii) Tendency of calculated characteristic values with increase of vibration frequency was partly disagree with that of experimental values.