How to Measure the Error of Roundness in Precision Parts Processing
The roundness error can be checked by using the roundness meter method and the two-point method and three-point method in the processing of precision parts. The rule of the roundness tester is to place the measured workpiece on the worktable of the roundness tester, align the rotation axis, and make the measuring head of the roundness tester contact the outer circle of the workpiece and rotate. The final measurement results are displayed through sensors, amplifiers, filters and calculation circuits. If the output is the figure of the actual contour, the concentric circle template package can be used, and the difference between the radii of the two containing concentric circles is taken as the roundness error of a section. The roundness tester is suitable for parts with high measuring accuracy requirements.
Two point method and three-point method When the shape of the measured profile is an even number of edges and circles, the roundness error can be measured by two point method. Use calipers, micrometers, micrometers and other measuring instruments to measure the maximum difference of diameter along the entire circumference of the normal section circle, and take half of it as the roundness error of the section circle,
Since the circles with the largest and smallest diameters are not necessarily concentric, this method is only an approximate measurement.
When the measured contour is an odd edge circle, the roundness error cannot be measured with the two-point method, and the three-point method can be used for measurement. Support the measured workpiece with a V-shaped frame, measure the maximum difference value of the workpiece rotation cycle with an indicator, and take it as the roundness error of the section generally. Common included angle of V-shaped frame α There are 60 °, 72 °, 90 °, 108 ° and 120 °. The three-point method can also be used for high-precision measurement in precision parts processing.
