Modeling Of Shear Angle Calculation Based On Minimumof Plastic Deformation Energy

Metal-cutting process is a very complex dynamic physical processes, related to a particular strain, strain rate and temperature range of mechanical properties of materials. As one of the most important parameters in cutting, shear angle influences not only cutting force, tool and the contact length between tool and chip, but also influences the distribution of stress on the rake face and reflects the degree of deformation in cutting. So, the study of the shear angle is the foundation of the cutting mechanism.Based on the relationship of cutting force and cutting geometry developed by Oxley, effect of plastic deformation energy on the primary shear zone and secondary shear zone, the shear angle was analyzed through calculation of stress and strain on the primary and secondary shear zone during machining. Equilibrium shear angle was defined as corresponding to minimum of total plastic deformation energy. Meanwhile, the cutting force and temperature had been measured in orthogonal cutting tests of 45 steel under different cutting conditions. After chip treatments, shear angle and hardness of chip had been measured under different conditions. Through the observation of orthogonal cutting test results this article obtained the cutting force, temperature, shear angle and hardness under different cutting conditions.In the verification of the model, the shear angle under force equilibrium, minimum power and minimum plastic work by uncorrected Oxley cutting model was calculated comparing with the experimental results. It could be seen that the calculation from the force equilibrium and minimum plastic work was good agreement with the experimental results, but there was still some gaps.Accordingly, the initial shear angle was introduced in the model. The shear plane begins to spin when shear stress equals shear strength and the initial shear angle was calculated. Last the cutting parameters were imported to the new model and cutting force, temperature and shear angle were exported. It could be seen that the model is more accurate and more consistent with the actual cutting process.