7. Conclusions
To reduce the environmental impacts of the manufacturing processes, it is the first step to estimate the energy consumption of machining processes. In the current work, energy supply models of CNC machine tools have been established through developing the power models of each machine tool Therblig which is defined as the fundamental motion of machine tools. Based on the theoretical analysis and experimental study, the power models of the Therbligs are divided into four categories:
1. Constant power model I for Therblig CFS. The model is constant and its value is obtained directly from the rated power of the relevant energy sources in machine tools’ specifications.
2. Constant power model II for Therblig SO, L, TS and TC. The models are constants and their values are estimated with experiments and statistical analysis.
3. Function power model I for Therblig SR, XF, YF and ZF. The models are functions of machine tools parameters and machining process parameters, the coefficients in the functions are estimated with experiments and statistical analysis.
4. Function power model II for Therblig C. The model is a function of machine tools parameters and machining process parameters, the coefficients in the function are calculated with theoretical analysis.