Research On Geometric Error Modeling,Analysis And Compensation Machining Of Ultra-precision Lathe

At the present,the technology of ultra-precision machining is widely used in optical device manufacturing,precision equipment manufacturing,national defense and so on.As the critical equipment for the development of ultra-precision machining technology,ultraprecision maching tool is fabricated and assembled in the highest standard,but the presence of spatial geometric errors can’t be absolutely avoided.These errors will be reflected on the surface of workpiece,and reduce the processing quality,so it’s necessary to study the influence of these errors,and increase the processing quality by the method of adjustment or compensation.Surrounding the geometric errors of ultra-precision lathe,this thesis will carry out the work of error modeling,error measurement,sensitivity analysis,error identification,etc,and related machining and compensation experiment will be done.The main contents are as follow:Firstly,to reflect the relationships between 21 geometric errors and the final machining errors,this thesis uses homogeneous coordinate transformation and the theory of multi-body system to build up the geometric error model of ultra-precision lathe.After the modeling work,the geometric errors of linear axes are measured by laser interferometer,which can partly parameterize the error model.Secondly,to analyze the proportion of different geometric error terms in the final machining error,this thesis uses Sobol sensitivity analysis method.On the one hand,the geometric error sensitivity is calculated under the whole machining volume of the ultraprecison machining tool,whose results can show the influence rules of all geometric errors comprehensively.On the other hand,sensitivity analysis is carried out for specific machining shapes,which provides the theory basis of error identification.Finally,some machining and compensation experiments are executed on Nanoform 250 ultra-precision lathe.At first,face turning is carried out on aluminum alloy(Al6061),then the compensation experiment is carried out after the identification of machining errors.Later sinusoidal array surface is processed and compensated by using the slow tool servo techniques,the results of compensation experiments verify the effectiveness of the above work.