Estimation of tool wear of a gun drill using the signal curve pattern of feed force
This study concentrates on gundrilling and the related feed force signal in time domain, and possibilities of using this signal in drill wear monitoring. The behavior of the feed force was studied in a normal gundrilling procedure, and also in a situation where the feed was stopped just before guidance feed was replaced by actual drilling feed. Stopping the feed caused a new kind of behavior in the pattern of the feed force curve, which could be used in monitoring the extent of drill wear. Regression models were created in order to estimate the mean flank wear in the cutting edges, flank wear in the drill tip, and longitudinal wear based on the pattern of the feed force curve when cutting conditions remain constant. Based on the test results, it was concluded that from the pattern of the feed force curve monitored in time domain and modified by stopping the feed, it is possible to predict the extent of the wear of the gun drill.