Journal of Advanced Mechanical Design, Systems, and Manufacturing (Jun 2024)
Enhancing engagement behavior in small-diameter deep drilling through ultrasonic vibration-assisted drilling and quantitative evaluation of hole dimensions
Abstract
This study investigates the effects of ultrasonic vibration-assisted drilling with a 0.3 mm diameter drill on engagement behavior and hole dimensions. The study addresses the increasing demand for small-diameter deep drilling in fuel injectors and medical instrument applications. The proposed “suitable ultrasonic vibration-assisted drilling” method is introduced to optimize small-diameter deep drilling processes. The chisel-walking phenomenon in conventional drilling is a challenge addressed in this study, and ultrasonic vibration-assisted drilling was explored as a potential solution. At first, the engagement behavior observation experiment was conducted. Circularity improved significantly when ultrasonic vibration amplitudes exceeded 4 μm, with a corresponding improvement in position deviation at amplitudes of 10 μm. In the condition of ultrasonic vibration amplitude was 4 μmp-p, and spindle speed of 500 and 1,000 min-1, the circularity dramatically improved, almost 0 μm. The chip removal volume in this condition was 53.07 μm3 on one period of ultrasonic vibration. From comparing the chip removal volume with other experimental conditions, the engagement behavior can be improved by reducing the chip removal volume as much as possible. Based on the engagement behavior observation experiment results, the experimental conditions were applied to the suitable ultrasonic vibration-assisted drilling, and the hole dimensions were measured. During the engagement, the spindle speed, the chip load, and the ultrasonic vibration amplitude were set to 1,000 min-1, 1 μm/tooth, and 4 μmp-p, respectively. The variation in the size of the holes was 0.0024 mm compared with 0.0043 mm in conventional drilling. Furthermore, when the ultrasonic vibration amplitude was applied 1 μmp-p during engagement and deep drilling, the dispersion was further improved to 0.0015 mm. The results show that suitable ultrasonic vibration-assisted drilling suppresses the variation in hole dimensions compared to conventional drilling.
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