Analytical modelling of parallel multidirectional cutting of slender shafts

• A concept of the parallel multidirectional turning is proposed. • An analytical model for the parallel multidirectional turning is established. • Effects of process parameters on forces, temperature, power, and machining error are analyzed. Slender shafts have wide application on the aerospace, automotive and medical devices. However, they are prone to bending deformation during cutting process due to their low rigidity, resulting in poor machining accuracy and efficiency. A parallel multidirectional cutting (PMC) method is proposed using two tools to simultaneously cut the workpiece in forward or reverse directions contributing to overcome the problem of large deflections of these shafts. The main concept and PMC shared and unshared cutting modes are elucidated. An analytical model for PMC is established including chip geometry model, cutting force model and workpiece deflection feedback model. Given tool geometry, feed and depth of cut, chip load is accurately calculated using cutting edge discretization. The Johnson-Cook constitutive model is used to determine shear stress and shear force on the primary shear plane, and therefore the three-dimensional cutting force is obtained. The force condition of the workpiece is analysed under two clamping methods and the deformation of the workpiece is calculated and feed back into the model. On this basis, the influencing mechanism of cutting force, cutting power, cutting temperature and machining error of PMC is explored under different cutting modes, machined shaft geometry, tool parameters and cutting parameters. The smaller-the-better characteristic of Taguchi's method and signal-to-noise ratio are used to analyse the effect of cutting parameters on the PMC performance. Furthermore, an experimental validation is conducted to verify the cutting power, temperature, and diameter errors obtained by the proposed model, and the result shows a strong correlation with simulation predictions. The proposed method significantly improves machining precision and efficiency, with promising applications in high-precision manufacturing industries such as aerospace and medical device production.