Study on the non-free plastic shear removal of material and cutting-induced deformation of micron-submicron grooves

The shear interference and chip removal interference between different tool edges during non-free cutting are the main reasons for the deformation of micron-submicron grooves. To our best knowledge, the understanding of the non-free cutting of micron-submicron grooves is still not well established. This paper provides new insight into the material removal mechanism and cutting-induced deformation of micron-submicron grooves in non-free cutting. A novel variable shear angle removal model, revealing the difference of material shear at different positions of the tool edge, is established by infinitesimally segmenting the tool edge after analyzing the shear interference and chip removal interference mechanisms. An equation of the local shear angle enables the mathematical derivation of the topography of the shear surface and chip cross-section in the non-free cutting of micron-submicron grooves. The distribution of shear stress in the shear zone is calculated by establishing the relationship between the shear angle and shear stress based on the unequal division shear zone (UDSZ) theory and Johnson-Cook theory. Furthermore, a mechanics model of micron-submicron groove cutting, revealing the deformation mechanism of the micron-submicron grooves, is established using the differential cutting force method. Finite element simulations and high-speed cutting experiments are conducted to analyze the cutting microstate between the tool and the material and the dynamic deformation of the micron-submicron grooves during non-free cutting. The stress trend of the elastic nodes on the tool edge verifies the mechanics model, and the chip morphology verifies the formation of the shear surface and chips. The degree of non-free cutting is higher at the tool edge infinitesimal segments (TEISs) closer to the tool tip, resulting in a smaller shear angle, which makes the extrusion stress suffered by the groove increases nearly twice from top to bottom. The material flow due to dynamic deformation causes the relative cutting line of the rear-side tool edge to shift forward. The deformation of the micron-submicron grooves is related to the stiffness of the structure.