Study on the critical negative rake angle of the negative rake angle tool based on the stagnant characteristics in micro-cutting

Abstract

The critical negative rake angle of negative rake angle tool is the critical criterion for the state of cutting and plowing in micro-cutting. It affects the flow characteristics of cutting material, the deformation state of chip, the quality of the machined surface, and the amount of tool wear. Meanwhile, a stagnant region often appears in front of the tool surface when a negative rake tool is used to cut the plastic metal material, which would increase the actual negative rake angle. Therefore, based on the stagnant characteristics and the infinite shear strain approach, this paper constructs a critical negative rake angle model, and the orthogonal cutting experiment and the finite element model are used to verify the correctness of the model. By analyzing the deviation of the effective critical negative rake angle (theoretical value) and critical negative rake angle (experimental value), it can be known that the theoretical value is 0.36–4.15% larger than the experimental value, which indicates that the model considering the existence of stagnant region is closer to the actual critical negative rake angle. In addition, the relationship between the stagnant region (the deviation) and the multi-cutting factors can provide experimental basis of angle for solving the effective critical negative rake angle when the critical negative rake angle is known.