The purpose of this paper is to present a new method to optimize the micro drill bit based on finite element analysis, and analyze the performance of the asymmetric helix groove micro drill bit and provide a way to conduct the optimization of micro drill bits.
First, the stress and deform of the micro drills were analyzed in ANSYS. Second, the influence of helix angle, web thickness and ratio of flute to land on stiffness was explored. Combining the former two results, a better set of parameters were optimized. Third, the modal analysis and harmonic response analysis of the optimized micro drill bit were analyzed in ANSYS. Finally, an experiment was carried out to verify the performance of the asymmetric helix groove micro drill bit.
The stress and deform of the asymmetric helix groove micro drill bit are not symmetric. The rigidity is getting better with the web thickness increasing in the selected range; while, the rigidity is getting worse with the helix angle and ratio of flute to land increasing in the selected range. The natural frequencies of the optimized micro drill bit are far away from the excitation frequency, and the response displacement is very small under the excitation of the spindle. In the drilling experiment, the optimized micro drill bit performs well.
In this paper, the diameter of the asymmetric helix groove micro drill bit was 0.3 mm and the cross-section shape was not considered. The future research work should consider different diameters and cross-section shapes.
Analyzing the influence of three main geometry parameters on the rigidity in ANSYS, a better set of parameters were optimized from the analysis results. The drilling experimental results show that this method is of great significance for obtaining the appropriate parameters of asymmetric helix groove micro drill bits.
This research work was funded by the project of the Shenzhen Science and Technology Development Funds, under the grant number JCYJ20120613164044732.
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