A proposal of feed rate setting for high-speed CNC milling machines by the vibration-based method

Abstract

High precision and product surface finish quality are the main characteristics of these precision machine tools. Machining with different tool paths at different feed rates is applied to increase productivity. Today, machine tools using high-speed machining methods have been developed to shorten machining times and increase production capacity. However, the vibration of high-speed machine tools is the main cause of product quality reduction. The effect of the machining speed on the vibration diagnostic process of the machine is to choose the appropriate machining mode. This paper describes the vibration analysis methods of machine tools based on simulated results to determine the natural frequencies of vibration and dynamic modeling of the ball-screw feed drive system. Analysis of structural simulation results shows that the higher the rigidity of the machine, the lower the vibration amplitude, and the greater the ability to absorb and suppress vibrations for the machine tool without using dampers. Meanwhile, the combination of the measurement analysis and dynamics modeling on machine tools is an effective method for optimizing speed and controlling machining vibrations. First, the finite element model (FEM) is applied to determine the stiffness analysis and the natural vibration frequency of the machine tool. The simulation results are analyzed and compared with experimental measurement results. The vibration frequency of the ball-screw drive system during machining at different feed rates is also modeled and verified by the measurement results. Finally, the results from the proposed methods are used to predict the vibration frequency of the system, especially the ball-screw through the feed drive or rotational speed. In addition, the purpose of the proposed method is to prevent resonance by way of the forced frequency away from the natural frequency in high-speed machining. This paper proposes a survey method that can be applied for high-speed machine tools with different structures to choose an appropriate feed rate in machining.