Influence of eccentricity and tilt of cylindrical part’s axis on the measurement results of its diameters

Abstract The global sizes and calculated sizes of cylindrical parts are defined in ISO 14405-1. For their measurement based on the cylindrical coordinate system, the eccentricity and tilt of the axis of the cylindrical part may have much influence on the measurement results. In this paper, the circular section profile’s models of the ideal cylinder with eccentricity, eccentric angle and tilt angle were established, respectively, and the evaluation models of the global sizes and calculated sizes of cylindrical part were given. A series of groups of circular section profiles of ideal cylindrical parts with six nominal diameters were simulated under different eccentricities and tilt angles of these axes in the xoyz system. The global sizes and calculated sizes of the cylinders above were evaluated based on the simulated profiles above. The simulation results showed that the eccentricity and tilt angle of the axis of the cylindrical part have no much influence on the measuring results of the minimum circumscribed diameter, the maximum inscribed diameter and the minimax diameter. If the values of the axis’ eccentricity and tilt angle are large, the evaluated results of the least-squares diameter, circumference diameter, area diameter and volume diameter are much different from its nominal diameter. For modifying the measurement errors caused by the axis’ eccentricity and tilt angle, the models of △ D Le ( D n , e n ), △ D Lγ ( D n , γ n ), △ D CS ( D n , γ n ), △ D AS ( D n , γ n ) and △ D VS ( D n , γ n ) were respectively established by using polynomial fitting, and their fit goodness values showed that they can meet the precision measurement requirement of the least-squares diameter and calculated sizes of cylindrical parts.