ONLINE DETECTION OF THE BREAKAGE OF SMALL-DIAMETER DRILLS USING CURRENT SIGNATURE WAVELET TRANSFORM

This paper presents on-line tool breakage detection of small diameter drills by monitoring the AC servo motor current. The continuous wavele t transform was used to decompose the-spindle AC servo motor current s ignal and the discrete wavelet transform was used to decompose the fee d AC servo motor current signal in time-frequency domain. The tool bre akage features were extracted from the decomposed signals. Experimenta l results show that the proposed monitoring system possessed an excell ent on-line capability; in addition, it had a low sensitivity to chang e of the cutting conditions and high success rate for the detection of the breakage of small diameter drills. (C) 1998 Elsevier Science Ltd. All rights reserved.