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1. Three part method.
The three-point method can be used for measuring the roundness error of outer or inner circles with large shape errors at the edge of the piston rod. When measuring, it is necessary to place the workpiece to be measured into a V-shaped block, and then rotate the workpiece in the V-shaped block for one cycle to read the large and small indication values from the micrometer. Half of the difference between the two indication values is the roundness error of the outer circle of the workpiece to be measured.
2. Rotation axis method.
Roundness tester is a measuring tool that uses the rotary shaft method to measure the roundness tolerance of the piston rod. This system has two forms: sensor rotation and workbench rotation. During testing, the circular trajectory formed by one revolution of the axis in a precision shaft system can be compared to the measured circle. The difference in circumference radius is converted into an electrical signal by an electrical length sensor. After circuit board processing and computer calculation, display the roundness error on a display or record the contour of the measured circle with a recorder.
3. Two point method.
The piston rod two-point measurement method is mainly applicable to measuring the roundness tolerance of outer or inner circles with uniform edge shape error. When measuring, a micrometer and a comparator can be used to measure, and then half of the diameter difference on a section of the measured circle can be taken as the roundness error of that section.
4. Coordinate method.
In general, the coordinate measurement method requires measurement on a coordinate measuring machine. During the measurement process, the coordinate values x and y of several points on the measured circle need to be measured based on the pre-selected Cartesian coordinate system, and then the roundness tolerance is calculated by an electronic computer based on the selected roundness error evaluation method.