Research On Energy Supply Modeling Of Computer Numerical Control Machine Tools For Low Carbon Manufacturing

Machining processes are widely used in manufacturing industries and consume large amounts of energy. Research suggests that it is essential to characterize machining processes energy consumption for low carbon manufacturing. However, there is a lack of energy supply data and models of machine tools which makes calculation and optimization of energy consumption hard to carry on. This Thesis is mainly concerned with the energy supply prediction of movements and material removal operations of computer numerical control (CNC) machine tools. Hybrid theoretical experimental modeling method is proposed to provide accurate energy supply data of CNC machine tools for energy consumption calculation of machining processes. Several efforts have been achieved in this thesis and listed as follows:In chapter1, scientific backgrounds, the origin, purpose and significance of this thesis were introduced. The state-of-art concerning this field was reviewed, and the contents and framework of the thesis were elaborated.In chapter2, the movements of CNC machine tools were listed. Modeling methods of energy supply of CNC machine tools’ movements were given. Power and cutting force data acquisition devices were set up. Then the power and time of basic movement, cutting fluid spraying, cutting fluid spraying start and automatic tool changing were obtained through measurements.In chapter3, the piecewise function that is used to describe the power of spindle rotation at multi-transmission chains was established. The power of spindle rotation at different rotational speeds under different transmission chains of CK6153i CNC lathe was measured, and the power model of spindle rotation was obtained with statistical analysis of the observed data. The energy supply of spindle rotation acceleration was modeled as a function of initial and final spindle rotational speeds. As coefficients in the theoretical models are difficult to obtain, experimental methodology to acquire energy supply models of spindle rotation acceleration was proposed. The effectiveness of the theoretical and experimental modeling methodology was validated. The feed power was modeled as a quadratic function of feed rate. The power of X and Z-axis feed at different feed rates of CK6153i CNC lathe was measured, and the feed power models were obtained with statistical analysis of the observed data. The energy supply of rapid feed were modeled as a function of feed distance, and the experimental methodology to acquire energy supply of rapid feed was proposed. The effectiveness of the proposed theoretical and experimental modeling method was demonstrated.In chapter4, the exponential power models of external turning and face milling were established. Using orthogonal experimental design,45carbon steel,6061aluminum and QT500-7ductile iron were selected for cutting tests in turning,45carbon steel was selected for cutting tests in milling. The coefficients in the power models were obtained through multiple linear regression analysis based on the experimental results. The obtained models were compared with those from literature, and results show that developed models provide more accurate prediction of cutting power than others.In chapter5, two different CNC lathes, a CNC milling machine and a machining center were selected for experimental study. Energy supply of the selected machine tools was modeled according to the experimental results. The suitability of the proposed energy supply modeling methodologies in different types of CNC machine tools was demonstrated.In chapter6, the main research contents and the innovation points in this thesis were summarized, and the future researches were forecasted and discussed.