Research On The Scheme Design System And Its Key Techniques For Machine Tool Structure

High-end CNC machine tool is the essential manufacturing equipment of precision parts in the military,aerospace,aviation,and machine tool industries,the strategic fundamental facility for guaranteeing the development of the national defense and top end industries,and the embodiment of the comprehensive level of advanced manufacturing technology of a country.Machine tool structure with high-stiffness,good dynamic performance and lightweight is a powerful guarantee for machining with high efficiency and precision.Hence,scheme design process of machine tool structure is the critical stage of design procedure of machine tool.However,the traditional structural design process of machine tool is an experience-based,intuition-based and cut-and-try approach.It is quite clear that it would lead to repeated design and be difficult to guarantee the design quality.Aiming at these problems,an integrated structural design framework for machine tools is proposed in this paper.In addition,a methodological system,which could support the top-down design of machine tool,is established.It contains the conceptual design methodology of machine tool based on topology architecture model,the modeling methodology of machine tool component oriented to design and analysis,the parametric modeling methodology based on associated feature,and the CAD/CAE integration method based on analysis feature.The main work is as follows.A novel integrated framework for design and optimization of a machine tool structure is presented,which can combine knowledge-based design and multi-stage optimization with the CAD/CAE integration technique.To realize the framework,a topology architecture model,which consists of a skeleton model,a stiffness model,and a parametric dynamic model,is introduced to integrate the conceptual design knowledge of machine tool with a specific topology architecture type.A two-stage scheme design process of machine tool structure based on the topology architecture model is proposed.In the conceptual design stage,the principal structural parameters,which critically affect the performance of the entire machine,are determined preliminary,based on the embedded constraints and external inference.Then,based on the stiffness model and dynamic model,the static and dynamic stiffness matching designs are performed to obtain the reasonable stiffness and weight value of each structural part or functional component.In the second stage,the allocated structural parameters,stiffness and mass values obtained from the first stage are taken as constraints,to guide the selection of functional components,and the optimization of structural parts.A conceptual design methodology of machine tool based on topology architecture model is introduced.Firstly,a parametric multi-skeleton model for machine tool structural design is proposed.By systemically organizing geometric and non-geometric elements that constitute the skeleton model,it could effectively integrate the topology architecture knowledge as well as geometric modeling knowledge of machine tool.Then,an intelligent decision-making method for the principal design parameters of machine tool is proposed.It could be used to combine the design knowledge inference based on inference information model and IF-THEN rules with the inner constraint solving.Finally,based on the stiffness model and parametric dynamic model,the technical process to accomplish static and dynamic stiffness optimization and matching is given.A rapid scheme design methodology of machine tool structure is introduced.Firstly,an assembly and analysis oriented component modeling methodology is proposed.At the geometric hierarchy,the simplified CAD model of component is established,which is convenient for meshing and interface modeling,as well as supports the expression of the design scheme.At the information model hierarchy,materials,interface mechanical property parameters are added to meet the information integration demand of CAD/CAE.Secondly,parametric templates of representative structural parts are established,and the multi-objective optimization process of structural part is formed.Finally,a parametric modeling method based on associated feature is introduced.With the aid of the application programming interface(API)of the CAD system,the interface feature information is abstracted to automatically generate the corresponding assembling feature and locating feature.By this manner,it can effectively keep the relevance between CAD models.On the basis of the above work,with the help of the distributed design function of CAD software,a scheme design of machine tool structure for functional component selection and structural part optimization is established,taking the parametric multi-skeleton model as its core.A CAD/CAE integration method based on analysis feature is introduced.Firstly,based on systematically summarizing the FE modeling strategies of representative interfaces of machine tool,the FE model of entire machine tool is abstracted as a whole as several sets of “solid elements” connected by several sets of spring elements at the interfaces.On this basis,an analysis feature model is proposed,in which two sets of analysis features,namely “solid-body” feature and “interface” feature,are defined.In addition,the object-oriented model of the analysis feature for the machine tool is presented.Secondly,by exploiting identification feature extracting technique,an analysis feature extraction method is proposed based on the assembling feature and interface feature.It can effectively integrate the FE modeling knowledge of interface,and accomplish the relevance between CAD and CAE models.Finally,with the aid of the feature mapping technique,an automatically generating method from the analysis feature to the scripting code of CAE software is introduced.Each type of analysis feature corresponds to a single scripting segment.Thus,by feature mapping and scripting code recombination,the scripting code for FE modeling,analysis job creation,and result viewing is generated to automate the FE modeling and simulation of the machine tool.On the basis of the work mentioned above,an integrated structural design system for machine tools is developed base on Pro/E API,Visual C++ and Microsoft Access database.Design and improved design of two horizontal machining centers with box-in-box architecture were carried out to verify the feasibility and efficacy of the proposed design theory and methodology,and the design framework.