Modeling And Structure Improvement Of Machine Tool Joint Considering Joint Modeling

The development level and technical standards of the machine tool directly reflect the development trend of a country's manufacturing industry,it is also one of the evaluation criteria of the national comprehensive power of industrialization.The establishment of accurate dynamic model is the prerequisite and basis for the study of the dynamic characteristics and structural optimization design of machine tools,the dynamic characteristics of machine tools are affected to a great extent by the bolt joint in each part of the machine tool,the modeling of bolted joint is a difficult problem,domestic employees will focus on the whole machine tool modeling,ignoring the combination of modeling methods,the relevant issues of the study is not deep enough.Therefore,it is very meaningful to study the modeling method and the method of parameter identification at the joint part of the machine tool bolt.In this thesis,the dynamic model of the experimental platform with bolt joint is studied,including the modeling process of the bolt joint and the process of solving the parameters of the joint part.The structural optimization design and analysis of the established dynamic model,specific contents are as follows:Firstly,a simple bolt joint test specimen is designed and the physical model is used to study the modeling method and parameter identification method.Determine the method to establish the combination model of the spring elements,the spring element is evenly distributed on the circumference of the spring element distribution modeling method based on the comparison of final circumferential distribution modeling method of spring number and diameter distribution.Using the method of finite element simulation analysis and test combined specimens with bolt spring element model of stiffness for the identification of the test,and the validity of the identification method is proved by changing the pre-tightening torque.Secondly,according to the idea of the village,the modeling method of the joint and the stiffness identification method are applied to the dynamic model of the joint of the machine tool bed,and the value of dynamic stiffness of the joint is identified.Then,the experimental modal analysis of the machine tool with the joint part is carried out.The simulation results and experimental results show that the error is within the allowable range.It is proved that the method is effective in modeling and stiffness identification.At last,the dynamic modeling of the experimental platform is established.Finally,the experimental platform of the bed for dynamic performance is analysed by the finite element simulation method,and the internal rib is identified as the weak link,then the structural optimization design module in ANSYS Workbench was used,through the analysis on the bed in the floor size and position,completing the optimization design of bed structure,improving the dynamic characteristics of the whole,the body weight,saving the production cost.The method can be extended to the structural optimization design of other parts of the machine tool,which provides an important method and basis for the improvement and optimization design of the machine tool structure.