Design And Application Of Roundness And Cylindricity Error Eyaluation Algorithms

Roundness error is the variations between the ideal circle and the profile of thecross section. Cylindricity error is defined as the changes between measured columnand ideal column. Roundness and cylindricity error are taken as two importantparameters to judge the geometrical accuracy of turning parts. They are generallymeasured by the cylindricity measuring instrument. The value of roundness andcylindricity error are significant for evaluating performance and service life. Therefore,it is very important to evaluate roundness and cylindricity error precisely and quickly inhigh-precision manufacturing.Based on the form error evaluation principle in the precision measurement field,roundness and cylindricity error evaluation algorithms have been researched and appliedin this paper. Firstly, conventional evaluation algorithms and evaluation results ofroundness and cylindricity error are analyzed in detail. The experimental resultsillustrate the effectiveness. Secondly, a new algorithm of evaluating roundness andcylindricity error based on geometry optimization is presented. The optimization andlinearization methods used normally are not adopted in this algorithm. In this method,three types of roundness and cylindricity error can be obtained simultaneously bytransferring the distance formula between point to point or point to space line repeatedly.Then, based on error evaluation principle, a mathematical model with eccentric andinclined parameters is established. This method not only decreases the cost ofproduction but also improve the accuracy of roundness and cylindricity error evaluation.Finally, in order to improve the evaluation efficiency of roundness and cylindricityerror and realize the evaluation visualization, a set of software which containsevaluation and measurement of roundness and cylindricity error according to the latestrelevant national standards was developed based on VC++6.0. The experimental resultsshow that the designed software can not only meet the requirements of the measurementaccuracy but also has a friendly interface.