The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size,...The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size, machining range, machining precision and surface roughness. By means of fuzzy comprehensive evaluation method, the membership degree of machine tool selection and the largest comprehensive evaluation index are determined. Then the reasonably automatic selection of machine tool is realized in the generative computer aided process planning （CAPP） system. Finally, the finite element model based on ABAQUS is established and the cutting process of machine tool is simulated. According to the theoretical and empirical cutting parameters and the curve of surface residual stress, the optimal cutting parameters can be determined.展开更多
The recursion relation of preventive maintenance (PM) cycle is built up concerning the concept of effective age and age setback factor proposed in this paper, which illustrates the dynamic relationship between failure...The recursion relation of preventive maintenance (PM) cycle is built up concerning the concept of effective age and age setback factor proposed in this paper, which illustrates the dynamic relationship between failure rate and preventive maintenance activity. And the nonlinear optimal PM policy model satisfying the reliability constraints in finite time horizon following Weibull distribution is proposed. The model built in this paper avoids the shortcoming of steady analytical PM model in infinite time horizon and can be used to aid scheduling the maintenance plan and providing decision supporting for job shop scheduling.展开更多
Virtual dynamic optimization design can avoid the repeated process from de-sign to trial-manufacture and test.The designer can analyze and optimize the productstructures in virtual visualization environment.The design...Virtual dynamic optimization design can avoid the repeated process from de-sign to trial-manufacture and test.The designer can analyze and optimize the productstructures in virtual visualization environment.The design cycle is shortened and the costis reduced.The paper analyzed the peculiarity of virtual optimization design,and put for-wards the thought and flow to implement virtual optimization design.The example to opti-mize the internal grinder was studied via establishing precise finite element model,modi-fying the layout of Stiffened Plates and designing parameters of the worktable,and usingthe technology of modal frequency revision and the technology of multiple tuned damper.The result of optimization design compared the new grinder with the original grinder showsthat the entire machine's first orders natural frequency is enhanced by 17%,and the re-sponse displacement of the grinding-head has dropped by 28% under the first order natu-ral frequency and by 41% under second order natural frequency.Finally,the dynamic per-formance of the internal grinder was optimized.展开更多
A novel approach,which can be used for dynamic characteristics analysis of machine tools based on unit structure(US),is reported in this paper.The concepts of unit structures for design of machine tools are defined.In...A novel approach,which can be used for dynamic characteristics analysis of machine tools based on unit structure(US),is reported in this paper.The concepts of unit structures for design of machine tools are defined.In order to satisfy the dynamic characteristics requirement of high natural frequency and light-weight of US,a design method of multi-disciplinary optimization of NSGA-II about unit structures driven by natural frequency and mass is developed.Through analyzing the unit structures,key factors affecting the natural frequency and mass are extracted,and the mathematical models of natural frequency and mass about unit structures are also established by using central composite design and response surface model.The goal of high natural frequency and light-weight is reached by using the multi-objective genetic algorithms.The Pareto optimal set is also obtained.The dynamic behavior of US is investigated by the experimental modal analysis.To show the efficiency of the proposed novel method,the example of YKW51250 gear shaping machine bed is used.Through optimization of NSGA-II about US of YKW51250 machine bed,the natural frequency of YKW51250 gear shaping machine bed is increased by 30.4%and its mass decreased by 5.2%comparing with the original design.By studying the dynamic characteristics of the simplified machine tools bed,useful laws are obtained,and these laws can be used in primary design of NC machine tools structures.The optimal method based on US can be also applied to the dynamic optimal design of machine tools and other similar equipments.展开更多
基金Shanxi Province Science and Technology Research Project(No.20140321008-03)
文摘The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size, machining range, machining precision and surface roughness. By means of fuzzy comprehensive evaluation method, the membership degree of machine tool selection and the largest comprehensive evaluation index are determined. Then the reasonably automatic selection of machine tool is realized in the generative computer aided process planning （CAPP） system. Finally, the finite element model based on ABAQUS is established and the cutting process of machine tool is simulated. According to the theoretical and empirical cutting parameters and the curve of surface residual stress, the optimal cutting parameters can be determined.
基金Natural Science Foundation of China (No. 59889505)
文摘The recursion relation of preventive maintenance (PM) cycle is built up concerning the concept of effective age and age setback factor proposed in this paper, which illustrates the dynamic relationship between failure rate and preventive maintenance activity. And the nonlinear optimal PM policy model satisfying the reliability constraints in finite time horizon following Weibull distribution is proposed. The model built in this paper avoids the shortcoming of steady analytical PM model in infinite time horizon and can be used to aid scheduling the maintenance plan and providing decision supporting for job shop scheduling.
基金Supported by the National Natural Science Foundation of China(50375026)
文摘Virtual dynamic optimization design can avoid the repeated process from de-sign to trial-manufacture and test.The designer can analyze and optimize the productstructures in virtual visualization environment.The design cycle is shortened and the costis reduced.The paper analyzed the peculiarity of virtual optimization design,and put for-wards the thought and flow to implement virtual optimization design.The example to opti-mize the internal grinder was studied via establishing precise finite element model,modi-fying the layout of Stiffened Plates and designing parameters of the worktable,and usingthe technology of modal frequency revision and the technology of multiple tuned damper.The result of optimization design compared the new grinder with the original grinder showsthat the entire machine's first orders natural frequency is enhanced by 17%,and the re-sponse displacement of the grinding-head has dropped by 28% under the first order natu-ral frequency and by 41% under second order natural frequency.Finally,the dynamic per-formance of the internal grinder was optimized.
基金partially supported by the Leading Talent Project of Guangdong Province of Chinathe National Key S&T Special Projects of China on CNC machine tools and fundamental manufacturing equipments(Grant No.2010ZX04001-191 and 2011ZX04002-032)
文摘A novel approach,which can be used for dynamic characteristics analysis of machine tools based on unit structure(US),is reported in this paper.The concepts of unit structures for design of machine tools are defined.In order to satisfy the dynamic characteristics requirement of high natural frequency and light-weight of US,a design method of multi-disciplinary optimization of NSGA-II about unit structures driven by natural frequency and mass is developed.Through analyzing the unit structures,key factors affecting the natural frequency and mass are extracted,and the mathematical models of natural frequency and mass about unit structures are also established by using central composite design and response surface model.The goal of high natural frequency and light-weight is reached by using the multi-objective genetic algorithms.The Pareto optimal set is also obtained.The dynamic behavior of US is investigated by the experimental modal analysis.To show the efficiency of the proposed novel method,the example of YKW51250 gear shaping machine bed is used.Through optimization of NSGA-II about US of YKW51250 machine bed,the natural frequency of YKW51250 gear shaping machine bed is increased by 30.4%and its mass decreased by 5.2%comparing with the original design.By studying the dynamic characteristics of the simplified machine tools bed,useful laws are obtained,and these laws can be used in primary design of NC machine tools structures.The optimal method based on US can be also applied to the dynamic optimal design of machine tools and other similar equipments.
