Inspection Technology Of Surfaces Using CMM And Roundness Error Evaluation

With the quick development of modern science and technology,the inspection accuracy of parts is increasing day by day.As the “eye” of product manufacturing,quality inspection has become an extremely important part in industrial production.Precision product design relies on high-precision processing,and high-precision manufacturing requires high-precision testing.So far,coordinate measuring machines(CMMs)are widely used in production test.They can measure most complex surfaces parts with high-precision,and become an indispensable measuring equipment in modern industrial inspection.This thesis focuses on the coordinate of software system of CMM,the influence of surface sampling points on the inspection accuracy,and the evaluation of roundness error,which reduces the inspection error of CMM,improve the surfaces inspection accuracy and efficiency,and measure the machining quality of rotary parts.The major contributions of this work include:(1)The research background,significance,research status and development trend of surfaces inspection are discussed.According to the problems of surfaces of CMM inspection technique and roundness error evaluation at present,this thesis puts forward the research contents,i.e.coordinate system establishment of CMM,sample saturated and roundness error evaluation.(2)The influence of coordinate system establishment of the CMM on the inspection errors is studied.First of all,the establishment of coordinate system and the pretravel error compensation are theoretically analyzed.Then,the algorithm of coordinate system establishment and four-points to find the center are introduced.Softwares of coordinate system and four-points to find the center are compiled by Visual C++ language,and integrated into the software system of CMM.Lastly,algorithms of coordinate system software and four-points to find the center are carried out through standard gauge inspection experiment.(3)For the problem of improving the inspection efficiency and accuracy of parts,the sample saturated is studied.Firstly,the measuring point arrangement and sampling points number are theoretically analyzed.Then,a normal distribution model is introduced to determine the type of error model of the surface.Experiments for surface inspection are designed and experimental results in mathematical are analyzed.In the end,the optimal number of sampling points is determined by the normality test.(4)The improved exhaustive algorithm and the search algorithm of center in roundness error evaluation are presented.Firstly,the mathematical model of roundness error under four criteria is given.Then,the basic principles of improved exhaustive algorithm and search algorithm of center are described in detail.Lastly,the improved exhaustive algorithm and the search algorithm of center are respectively verified with examples from the literatures,and the results show that the algorithms proposed in this paper has better accuracy.