Analysis of Cutting Behavior during Tapping and Measurement of Tool Edge Temperature Measured by a Two-Color Pyrometer

摘要

This paper proposes a method for measuring the tool edge temperature during tapping. The infrared ray from the tool edge of the tapping tool was measured using a two-color pyrometer with an optical fiber. In addition, the vibration caused by contact between the first-act tool edge and the workpiece was sensed by an acceleration pickup. The outputs of the pyrometer from the tool edges and chips could be distinguished by analyzing the cutting behavior in the tapping process. The tool edge temperature was successfully measured for tapping of AISI 1045-based free-machining steel and stainless steels. The cross-sectional cutting area appears to control the tool edge temperature. The maximum tool edge temperatures with thee two steels at a cutting speed of 30 m/min reached almost 300 and 400°C, respectively. The cutting torque for stainless steel 303 was 3.4 N·m lower than when tapping stainless steel 304. The tool edge temperature for stainless steel 304 reached the maximum value of 510°C. The temperature for stainless steel 303 was about 100°C lower than of stainless steel 304.The tool edge temperature for stainless steel 304increased linearly with the cutting speed. The rate of increase in the tool edge temperature with increase in cutting speed from 25 m/min to 30 min was larger than that from 20m/min to 25min. Therefore, the tool edge surroundings apparently became harder with an increase of cutting speed.