Energy Consumption Characteristics Of Feed Drive System In CNC Machine Tools

In China, machining system is in vast quantities and most widely used in industrialfield and the amount of machine tools occupies the largest in the world with the numberof7million.As a result, they have consumed a great deal of energy in the processing.Consequently, it is of great importance to study the characteristics of machine tools.Nowadays, with the development of numerical control technology, CNC machine toolsoccupy larger proportion in China than before. Compared with traditional machine tools,CNC machine has a series of different characteristics, such as more energy sources andmuch more complicated energy law. Feed drive system is an essential part of CNCmachine tools and the characteristics of it are still not fully discovered. Therefore, thisthesis mainly focuses on the characteristics of energy consumption for feed drive systemof CNC machine tools, and the principal work contains the following.Firstly, the energy structure of CNC machine tools is described. After that, theenergy flow theory of feed drive system is proposed. In addition, the characteristics ofenergy processing flow and energy loss are analyzed, which provide a basis to constructthe power model in the following step.Secondly, based on the structure of feed drives of machine tools, the feed drivingdynamics is analyzed for each part. Accordingly, dynamic equations are constructed andsimilarly the equation for the output torque of servo motor can be obtained. Also, thecontrol system of feed drives is analyzed and the relationship equation between torqueand armature current can be acquired. In this way, the feed driving power model ofCNC machine tools is constructed through the combination of above achievements.In the next step, this thesis analyzes the characteristics of idle power and cuttingpower for feed drives through the above feed driving power model, respectively. Inaddition, energy efficiency and energy utilization ratio are proposed and theircharacteristics are analyzed. The analysis results mainly focus on several points: In theidle processing status, idle power of feed drive system is approximately a monotoneincreasing quadratic function in term of the angular velocity of servo motor while theinfluence of table load mass is minuteness. Comparatively, in the cutting processingstatus, when the angular velocity of servo motor is constant, input power of feed drivesystem is approximately a monotone increasing quadratic function in term of the feedforce; when the feed force is constant, input power of feed drive system is approximately a monotone increasing quadratic function in term of the angular velocityof servo motor. Furthermore, the analysis also indicates that when the angular velocityof servo motor is constant, energy efficiency increases firstly and then decreases withthe rise of feed force; when the feed force is constant, energy efficiency increases firstlyand then decreases with the rise of the angular velocity of servo motor.Eventually, some confirmatory experiments and simulation analysis wereperformed on CNC machine tools. The results verified the effictiveness of the researchconclusion.