IN-PROCESS DRILL WEAR AND BREAKAGE MONITORING FOR A MACHINING CENTER BASED ON CUTTING FORCE PARAMETERS

There are many physical parameters in the cutting process that could be used for the in-process monitoring of cutting tools' working conditions. Of these parameters, cutting forces are strongly recommended by the investigators to be used because of their higher sensitivity and more rapid response to the changes in cutting states. In this paper, the variation in the dynamic behaviour of drilling thrust force and torque with drill wear, breakage and other kinds of fault forms have been investigated experimentally. The results and associated theoretical investigations indicate that, to make the monitoring system more reliable and suitable for a wider range of cutting conditions, both thrust force F(z) and torque T arising from drilling operations should be taken as associated monitoring quantities, rather than choosing just one of them. The methodology of signal signature extraction and data processing techniques are discussed and a practical monitoring strategy proposed.