Research On CNC Machine Tool Energy Modeling And Analysis Of Its Influential Parameters

Machine tool is the basic manufacturing equipment in today’s mechanical manufacturing industry. A considerable amount of energy is consumed in machining a workpiece into component. An upward surge in environmental awareness and rise of electrical energy costs due to shortage of energy sources have set the international energy conservation focus on machine tool’s energy consumption. The establishing of an accurate machine tool’s energy consumption model plays an important role for production life cycle assessment, supporting energy-saving design of machine tool system, guiding production’s manufacturing process planning, and more.In this work, with reference to a bulk of literature, CNC machine tool’s machining energy and specific cutting energy (SCE) are modeled for different operational levels and their dependence on various parameters are analyzed.Firstly, for the CNC machine tool’s energy consumption modeling, an experimental platform is set up that measures material’s cutting force and the whole machine tool’s power consumption simultaneously.Secondly, the energy consumption phenomenon, with respect to the material removal mechanism, is analyzed and modeled in form of an empirical formula. An index formula of specific cutting energy is worked out based on the experimental data related to a facing process performed on a turning machine. Cutting parameters mainly affect the deformation process during material removal and the friction between material and tool. The influencing trends of cutting speed, feed rate, and cutting depth on SCE are analyzed. It is found that feed rate is the most influential parameter for SEC followed by cutting speed and cutting depth.Furthermore, different CNC machine tools’energy consumption mechanisms are analyzed based on their various structures and energy consumption components. CNC machine tool’s energy consumption equation is modeled by dividing it into two parts. The energy consumption of machine tool’s auxiliary systems, including intermittent working systems and constant power working systems, are calculated by switch function. Moreover, the power consumed by main transmission system and other feed systems is modeled into three parts:idling power, cutting power, and load loss power. The conventional machine’s spindle idling power monotonically increases as the spindle speed increases whose speed governing is done mainly by a regulating mechanism. On the other hand, the high-end CNC machine’s spindle idling power depends on the motor’s characteristics. Nonetheless, both of the idling powers can be modeled by quadratic functions. The load loss during the machining process is fitted as a quadratic function of cutting power. The cutting power can be calculated by the material’s SCE.Finally, SCE at machine tool level is modeled, which supports production life cycle assessment and low-carbon manufacturing assessment inventory requirement. The whole machine tool’s SCE is divided into specific fixed energy, specific operation energy, specific material removal energy, and specific unproductive energy, where the former two parts are mainly determined by machine tool’s structure. The results show that improving material removal rate, especially by increasing feed rate and cutting depth, can improve machine tool’s energy efficiency, machining efficiency, and reduce total energy consumed in part’s machining.