The Analysis Of The Cutting Mechanism In Helical Milling Of CFRP Based On FEM And Hole-making Process Optimization

As a kind of new material used in aerospace manufacturing industry, carbon fiberreinforced plastic (CFRP) is a difficult-to-cut material with many good mechanicalperformances. The conventional drilling cannot satisfy the required precision andreliability in its application field. Helical milling, as a brand new cutting process forhole-making, changes the kinematic principle of cutting, increases the hole qualityand the cutting efficiency and decreases the costs. But there is limited study about thehelical milling on CFRP, so how to improve the hole-making quality from severalaspects seems to be more and more important, like the cutting mechanism of CFRP,the principle of the helical milling movement and the process parameters.The main work is as follows:First, the theory about CFRP cutting model in Abaqus was introduced, and a twodimension orthogonal cutting model was set up using Abaqus/Explicit solver.Through the analysis of the model, the damage mechanism under different fiberorientation is obtained. Based on the analysis above, the damage of the wall of holeswere studied, the forming reasons of the holes machined in helical milling were thenstudied.Second, the kinematics principle of helical milling was analyzed, translating thethree dimensional helical milling process into two dimensional plane analysis, and thematerial removal process in helical milling from two aspects was described: flankedge machining and front edge machining using mathematics. Then got the directrelationship between the ratio (the ratio between drilling and milling) and thediameters (the hole diameter and the tool diameter). Then, through the helical millingexperiments, the effect of the drilling-milling ratio on the quality of the hole wasstudied. The hole quality that were referred to includes the diameter on the entranceand the exit of the holes, the diameter of the hole, and the delamination on the exit ofthe hole.At last, the effects of the process parameters on the delamination of the hole exitin helical milling was studied, using delamination factor to qualified the delaminationdefault. The present work choose three cutting parameters of helical milling: spindlespeed, the feed rate in tangential direction per tooth and the screw pitch of the feeding spiral. The milling experiments are based on full factor experimental design. Anartificial neural network model (ANN) which described the relationship between thedelamination defaults and the cutting parameters was developed based on the data gotfrom the experiments. Through the prediction model, the effect of the cuttingparameters on the delamination is depicted with the intuitionistic plots. With theanalysis above, two major delamination influencing factors were pointed out.The present work analyzed the cutting mechanism and the principle of thekinematic, and optimized the cutting parameters of the helical milling. The studyabove provide a valuable reference for further study about the helical milling onCFRP and the extension of practical application of the helical milling process.