Abstract
The carbide tool for screw thread turning has been used widely in NC lathe. However, few studies have been performed about tool wear of the carbide tool for screw thread turning and the effects of tool wear on an accuracy of a turned screw thread. The present paper deals with the effects of tool wear in screw thread turning, and describes a setting method of a criterion for tool wear. The results obtained are as follows. (1) The tool wear brings the reductions of the front cutting edge and the side cutting edges. These reductions of the cutting edges decrease in the accuracy of a turned screw thread. (2) The irregularities of the same number of the groove wear appear on the flank of a turned screw thread. (3) Allowable flank wear lands are derived from the tolerance system for metric screw threads, and a criterion for tool wear in screw thread turning is proposed by means of the cutting force ratio. By making use of these results, a method for detection of tool wear and failure during turning screw thread is proposed. It is confirmed that the monitoring system is reliable.
