Thrust force prediction model coupled with the influence of material strain rate induced by cutting speed in CFRP drilling

In CFRP (carbon fiber reinforced plastics) drilling, the thrust force induced by the main cutting edge of drill bit is a crucial factor affecting the hole-making quality. The cutting speed induced by the spindle speed of machine can cause the changes of resin strain rate in CFRP materials, which affects their cutting performance and further affects the thrust force. Therefore, the cutting speed cannot be ignored in studying the drilling mechanism of CFRP. In this paper, the contact state between main cutting edge and workpiece materials in CFRP drilling is analyzed, the failure models of fibers are separately established under the action of rounding and rake face of main cutting edge, the resin strain rate caused by cutting speed is calculated. Ultimately, the Thrust force prediction model coupled with the influence of material strain rate induced by cutting speed in CFRP drilling is developed, and the accurate solution of fiber fracture process is realized. The reliability of the prediction model is verified by conducting experiments on drilling CFRP. Results indicate that compared to the case without considering the influence of cutting speed, the proposed model can improve the prediction accuracy of 9.8 %- 29.2 % in the spindle speed range of 7000-11,000 rpm. Additionally, the influence mechanism of cutting speed on the strain rate and modulus of resin, and the machining damage of material during CFRP drilling is revealed.