Study on Formation Mechanism of Saw-Tooth Chip of Titanium Alloy by FEM

摘要

A finite element model is developed to study saw-tooth chip formation mechanism of titanium alloy during cutting process. Several key finite element techniques, such as the material constitutive model, friction model on the chip-tool interface, chip separation criteria, adiabatic shearing model, and heat dissipation and transfer model are implemented to improve finite element simulation accuracy. Saw-tooth chip is simulated using this finite element model, and the predicted chip morphology and cutting force agree well with experimental results, showing the finite element model is reasonable. A detailed analysis of the saw-tooth chip formation process is performed and the chip formation mechanism is obtained. This research makes clear that the material is softened firstly close to tool tip, then leads to thermoplastic instability, and the structure of chip goes instability, which causes the shear localization, at last, concentrated slip of the first deformation zone is produced, and the saw-tooth chip comes into being.