Research On Carbon Emission Optimization And Greenness Evaluation Method In Cnc Machining Process

The rapid development of the world economy has improved people’s quality of life,however,the accompanying phenomena such as heavy energy consumption,predictable shortage of resources,and disorderly emissions of three wastes have also caused serious environmental problems.Manufacturing is one of the main sources of environmental problems as a large energy consumption and carbon emission source.The machining process is also a necessary part of the manufacturing,it will consume a lot of resources and energy,and produce solid,liquid and gas wastes.Its environmental impact has increasingly attracted the attention of academia and business.In order to ensure lowcarbon machining,optimizing the carbon emissions of the machining process and establishing a greenness evaluation system have become the current research hotspots.In this thesis,a new energy consumption prediction model for machining process was established for the various energy consumption characteristics of CNC machine tools.The energy consumption characteristics of machine tools were analyzed,the influencing factors of the machine tool energy consumption were discussed,the system boundary was determined,the energy consumption composition of machine tools was studied and the energy consumption formula was established,which accurately reflects the mapping relationship among the energy consumption,the material removal rate and the spindle speed,the concrete meaning of each coefficients in the energy consumption model were explained which is convenient for the determination of the coefficients and the understanding and application of the model.An online energy consumption monitoring platform was built to monitor the energy consumption of the machining process.Turning was used as an example to verify the accuracy and effectiveness of the model,and the purpose of accurate predicting the energy consumption through cutting parameters was achieved.In view of the wide and diverse characteristics of carbon emission sources in the cutting process,a model for quantifying carbon emissions during the cutting process was established.By analyzing the carbon emission sources of mechanical processing,the concept of exergy analysis was introduced to divide the boundary of the carbon emission system.Combining information flow and exergy analysis method in the cutting process,a method for quantifying the carbon emissions in the cutting process,i EC carbon emission model,was proposed.Taking turning process as an example,the change rules of carbon emission with cutting parameters were studied from both experimental and theoretical analysis methods,the causes of the change rules were analyzed and explained.The cutting parameters to minimize carbon emission were given.Aiming at machine tools,a life cycle carbon emission assessment model of machine tools was established based on life cycle theory.The contributions of functional units in the life cycle carbon emission assessment of machine tools were defined and analyzed,then a method for evaluating the life cycle carbon emission of machine tools based on functional unit was proposed,which divided the carbon emission of machine tools life cycle into five stages,and carbon emissions in the usage phase was mainly studied.Taking the life cycle carbon emission characteristics of CAK50135 di and PUMA200 MA as examples,the composition of carbon emission in the whole life cycle of machine tools was discussed,and the uncertainty analysis of carbon emission was carried out.In view of the interrelationship among carbon emission,product quality,processing efficiency,and costs during processing,considering the different focuses of rough and finishing processes,then low-carbon,low-cost,high-efficiency and low-carbon,highefficiency and high-precision multi-objective parameters optimization model were established separately.Based on the analysis of NSGA-II and entropy-TOPSIS methods,a multi-objective optimization algorithm based on optional objective constraints was further proposed.The significant factors in multi-objective optimization and the influence law of cutting parameters on each target were analyzed,and the concept of low-carbon and low-cost processing interval was proposed,which provides a solution for solving the choice problem between carbon emission and cost.Finally,in order to establish a greenness evaluation system that has good versatility,strong applicability,comprehensive evaluation indicators,and can meet the needs of people with different roles(process programmers,enterprise managers,market regulators),a greenness evaluation system for low-carbon processing based on optional evaluation dimensions was put forward.The evaluation system took technical indicators,economic indicators,natural resources and environmental impacts as the criteria layer for evaluation.It took fuzzy analytic hierarchy process,entropy weight method and subjective and objective comprehensive weighting method as evaluation methods,which divided carbon related indicators and efficiency indicators into several optional indicators to meet the evaluation needs of different dimensions.Multi-objective parameters optimization and greenness evaluation system for low carbon turning process was developed,and a case analysis of greenness evaluation for the turning process was carried out.