Modeling On Rotation Accuracy Degradation Of Machining Center Spindle For Reliability Virtual Test

The reliability test of machining center has the problems of long test period and high test cost,while the traditional reliability test has the disadvantages of high cost and low efficiency.In particular,the performance of the recession test,in view of the time cost and economic reasons,in the laboratory is almost impossible to complete,so through the computer powerful computing and simulation capabilities,the construction of virtual prototype,virtual prototype on the dummy test,to obtain low-cost and efficient reliability test results become an important research direction,it is also an inevitable requirement of industrial 4.0,but with the performance decline law as the research goal,there is not much research on the construction of virtual prototyping and performance modeling of machining center.In this dissertation,through the Natural Science Foundation of Zhejiang Province,with the support of NBP1100 type vertical machining center spindle as the research object,this dissertation makes a deep study on the model of reliability virtual prototyping and the fading characteristic models of rotational accuracy,including the following work:(1)According to the structure and characteristics of NBP1100 type vertical machining center and its spindle,this dissertation makes a simplified analysis of each part of the spindle,constructs the element structure of the spindle parts(basic unit structure),and establishes the virtual prototype model of the spindle based on the need of the concrete assembly process,the spindle running principle and the precision recession modeling.(2)Based on the above virtual prototype model,the method of determining the thermal load and boundary condition of the spindle is discussed.The calculation method of heating strength,thermal power and convective heat transfer coefficient of the bearing is determined,and then the thermal characteristic of the spindle of machining center is calculated by using the finite element method,and then the temperature field and thermal deformation analysis of idling and cutting state are completed respectively.(3)According to the assembly relation between the spindle parts,the main axis is equivalent to a rigid bar,the spindle rotation precision model is established,the sensitivity of the parameters in the model is analyzed quantitatively,the influence degree of each dimension error on the rotation precision is described,and the size of the parts with the most influence on the rotational accuracy is found.(4)Considering the influence of temperature field and thermal deformation,the temperature factor is coupled with the dimension error of key parts,and a comprehensive analysis model of rotational accuracy is established,which reveals the decline law of rotation accuracy under the condition of the dimension error and temperature coupling.In this dissertation,the analysis and calculation of the finite element temperature field are validated experimentally,and the test points are arranged at the position of the support bearing which has the greatest influence on the rotational accuracy.Comparing the test data with the calculated results,the finite element modeling method and the accuracy of the calculation results are validated,and the rotational precision model is verified by example,and the feasibility of the rotational accuracy model to describe the decline of spindle accuracy is validated.In this dissertation,in the case of relatively few resources,through the above research,from the theoretical discussion of the spindle rotation accuracy modeling method,from the temperature and key parts of the dimension error angle,the spindle rotation accuracy in the time axis of the decline law,it provides an algorithm basis for the construction of reliability virtual test system,and its research results also have important guiding significance in the design of spindle system precision maintenance,but because the research time is short,the model has not considered the influence of the parts ' shape and position error and vibration etc.The rotary precision model established in this dissertation also needs to be validated in a long time in the actual production process of the processing enterprise,in order to perfect the model.