Study On Several Key Techniques And Theories Of Boring-Milling Machining Center

"High-end CNC machine tools and basic manufacturing equipment" is one of the 16 major projects from National long-term Scientific and Technological Development Plan(2006 to 2020),and also the model of equipment manufacturing industry.However,due to the integrated non-linear effects of multiple factors,such as the structure,potential force,non-potential force and so forth,in the process,there are a variety of errors produced on the machine which conversely causes some side effects on the quality of workpieces.Therefore,in the machine design process,it's required to do some research on its static and dynamic characteristics,and employ the relevant theory and technology to effectively reduce or avoid the negative factors that may put adverse effects on the performance of machines,coupled with more stringent requirements for the machine tool resulted from the new industry development,the international research strength is on the way to converge and integrate with the increasingly heated subject.The geometric error estimate of components caused by potential force and non-potential force is an important branch of the research area of machine statics,and it's also a central issue and the difficulties for the research of geometric error correction technique described above within the category.In recent years,the research of recognizing the machine joint parameters has become an important basis and necessary branch for the research of machine dynamics,at the same time,in terms of the complex,high-speed,sophisticated modern CNC machine tool and the future machine with the feature of high flexibility,ultra-high speed,ultra-precision and high intelligence,their dynamic characteristic parameters will be the key index which can evaluate its performance,quality of products and processing products.Based on the above contents,regarding the TX1600G Boring-milling machining center as the research object,some key technology and theories during the research course of its static and dynamic characteristic will be discussed:(1)Correcting technology of ram's deflection based on the combination between error prevention methods and error compensation methodsStatic simulation for boring system of boring-milling machining center reveals the Static displacement behavior of its key components,and the ram's deflection is overproof because of the effect of ram's gravity,boring force,dimension,and other structure characteristics,therefore,the problem which was aimed is correcting by the combination between error prevention methods and error compensation methods in this paper.The multi-factor optimization method based on ISO stress cutting maps is proposed after the discussion among several error prevention methods,then the error model of ram's deflection is established based on the polynomial curve fitting method by least squares,furthermore,the structure compensation and NC compensation are realized through scraping method and NC compensation curve.A effective way is provided to the same problem of ram's deflection of machine tools because of the advantages of multi-factor optimization method which is well effected,easy to implement,low cost and error compensation methods which is low cost and can be easily implemented and controlled without mechanical auxiliary structures.(2)Prediction model for deflection of ram of boring-milling machine tools based on position-dependence and effect of structural characteristicsIn order to realize the prediction of ram's deflection of machine tool in drawing stage,the effects of position-dependence and structure characteristics to ram's deflection are analyzed based on the design model of ram and the starting point of broad applicability.Two coefficient which named positive effect coefficient of structural characteristics and negative effect coefficient of structural characteristics are firstly proposed and defined to correct the traditional formula of cross-section moment of inertia,furthermore,the prediction model for deflection of ram of boring-milling machine tools which includes continuity and position-dependence based on superposition principle and cantilever beam theory after the discussion about the effects of each load conditions to ram's deflection,the validity of the model above is verified by examples.Compared to the traditional model based on cantilever beam theory only,the model in this paper has good description precision,so that it can provide a quantitative basis to the structural design and prediction of ram's deflection of the same machine tools.(3)Identification methods to equivalent parameters for three typical kinds of joint in machine toolsThree typical kinds of joint in machine tools including fixed plane's joint,dynamic coupling plane's joint,cylindrical fixed joint are studied to determine the equivalent parameters of them.Firstly,the equivalent contact stiffness and viscous damping of fixed plane's joints in machine tools in the vertical and shear directions.Secondly,extracting the linear relation among its physical parameters in the rated conditions according to the differences among the loads,types and installation modes of railslider groups,and establishing the F-P-KC model combined with the conclusion of existing literatures,the related equivalent parameters of dynamic coupling plane's joints in machine tools are determined.Thirdly,proposing micro-element cylinder method for the first time aimed at the shortcomings of micro-element plane method,the models for equivalent rotating contact stiffness and equivalent axial stiffness are established to determine the related equivalent parameters of cylindrical fixed joints in machine tools.The above parameters provides a quantitative basis for the dynamic research of machine tools,while the F-P-KC model and micro-element cylinder method provides new train of thought more completed to the establishment of same models or methods proposing.(4)High-dimensional nonlinear dynamics theory based on the concept of big dataThe theoretical research and application situation of mechanics based on big data is still in its infancy.In this paper,based on the concept of big data which includes the characters,key technologies,applications,challenges,patterns of big data,supplied by the methods or concepts of position-dependence,position-dependent system,space movement view,motion vector,and so on,with the effect of orders,in-out,time-varying,dimension position,space motion considered,a dynamics model for mechanical system with varies characteristics of high order,multiple-input and multiple-output,time-varying,nonlinear,u dimensional features in ?dimensional space.Then the program mode solving process of the model above is provided based on the big data mode and amended Tustion method.Finally the train of thought analysis and high-dimensional data processing are discussed with the contents of database establishment,data fitting and visualization.The model establishment,solving process and data processing are the pioneering exploration to the field of high-dimensional nonlinear dynamics theory based on the concept of big data,which promote the subjects crossing and academic integration between big data theory and mechanical science and technology.(5)The set of modal,generalized relative displacement ratio and modal flexibility of machine tools based on high-dimensional nonlinear dynamics theoryThe modal field and generalized relative displacement field of machine tools are established based on the high order space model under the space motion theory and the core thought of big data patterns,then the set of modal,generalized relative displacement ratio and modal flexibility of machine tools can be obtained by logical assembling of the fields' data above after dealing with vector tropism weakening method and particular conversion method.Furthermore,the sets' data above should be fitting through polynomial curve fitting method by least squares and visualizing with layered processing method,while several recommendations to the visualization processing for high order large information volume of three axis machine tools are enumerated,consequently,several dynamic behaviors of machine tool which include modal jump,local vibration,modal domain first proposed in this paper can be discoursing,explaining and verifying by the results visualized.The big data mode explodes the limitation of traditional research mode for mechanical dynamic characteristics,so that it can obtain the full view of dynamic parameters information of machine tool above,simultaneously,it also indicates that the establishment of machine tool dynamic parameters' sets is necessary to give expression to the high degree precision of machine tool.In conclusion,the paper,which surrounds the topic of the static and dynamic characteristics of machine tool,has been studied on several key technologies and theories taking the TX1600G Boring-milling machining center as research object,and the key technologies and theories themselves,including the research achievements they obtained,have important reference significance to the innovation development of machine tool industry in the new circumstances.