Vibration response analysis of thin-walled workpiece considering material removal effects during machining with variable pitch end mill

As a typical vibration-damping tool, the variable pitch end mill changes the dynamic characteristics of the system as the material is removed, which alters the cutting vibration response and affects the workpiece’s quality. In this paper, first, a cutting force model for the variable pitch end mill is established, while the cutting force coefficients are determined through the cutting experiment. The accuracy of the cutting force model is revealed by comparing the simulation with the experimental results, and then the frequency spectrum characteristics of the cutting force are analyzed in the presence of various spindle speeds and interdental angles. Second, the dynamic characteristics of the machining system are analyzed by the modal test and the finite-element analysis. In continuing, amplitude–frequency characteristic curves are carefully examined to get the modal parameters of a variable pitch end mill and aircraft aluminum alloy workpieces of different thicknesses, and subsequently, the mode shapes are determined by modal analysis. Finally, based on the above cutting force model and the system modal parameters, the free and forced vibration responses of the workpieces with various thicknesses are analyzed by employing dynamic system modeling simulations. The relationship between material removal and vibration response is obtained, which indicates that the vibration amplitude of the machining system gradually increases as the workpiece’s thickness lessens. The obtained results of forced vibration response analysis for thin-walled workpieces machined with various interdental angles reveal that the fourth type of end mill has the best vibration damping effect.