Research And Simulation Of Roundness Error And Sphericity Error Evaluation Models

With the continuous development of ultra-precision technology in the field of precision manufacturing and nanotechnology,the processing accuracy of precision devices continues to increase,the size tends to be miniaturized,and the shape error also is required to higher precision.The roundness error of precision shaft devices is required to micro-nano scale.And the microsphere used in the measurement system is required to be as small as possible.For a micro-nano coordinate measuring machine(CMM),probing balls with diameters below a few hundred microns are needed,and their sphericity error have to be qualified within tens of nanometers level or even higher precision.However,the current research on the evaluation of roundness error and sphericity error is still in the exploratory stage,and unified standard has not been formed yet.Aiming at the shortcomings of roundness error evaluation methods and sphericity error evaluation methods,such as principle error,model error and complex mathematical models.A roundness error evaluation method and a sphericity error evaluation method based on the minimum coverage area method were proposed respectively.The following works have been finished in this paper:1?A new strategy for determining control points was studied.Then A roundness error evaluation method based on minimum coverage area method was proposed by combining the definition of roundness error and the geometric structure conforming to the minimum coverage area method with the new strategy,which can evaluate roundness error accurately.A sphericity error evaluation method was proposed to accurately evaluate the sphericity error according to the definition of sphericity error,the corresponding geometric structure models and the new strategy.2?The roundness error evaluation method and sphericity error evaluation method proposed in this paper were achieved separately by MATLAB software.And they were packaged into functions respectively,which is very convenient to call and maintain.3?Relevant test experiments were carried out to verify correctness and superiority of the proposed methods.The experimental results show that the evaluation methods introduced in this paper fully conforms to the definitions of roundness error and sphericity error.The proposed methods not only can accurately obtain roundness error and sphericity error respectively,but also have more superior performance by comparing with the evaluation results of other methods,such as fewer loops,higher efficiency and better stability,and so on.