175-200mm internal micrometer

175-200mm internal micrometerCorrect measurement method
1) When measuring and using a 75-100mm internal micrometer, it is necessary to connect the largest connecting rod to its measuring head, and sequentially connect it to the measuring contact to reduce the bending of the axis after connection.
2) When measuring, the change in the fixing and loosening of the micrometer head should be observed.
3) In daily production, when measuring holes with an inner diameter ruler, support the measuring contact surface on the surface being measured, adjust the differential cylinder so that the measuring surface on one side of the differential cylinder swings within the radial cross-section of the hole, and find the smallest size. Then tighten the fixing screw and take out the reading. There are also cases where the reading is taken directly without tightening the screw. There exists a problem of posture measurement. Attitude measurement: refers to the accuracy between measurement and use. For example, when measuring an inner diameter ruler of 75-600/0.01mm, if the dimension after connecting the extension rod to the micrometer head is greater than 125mm. The difference of 0.008 mm between the reading values when tightening and not tightening the fixing screws is considered as attitude measurement error.
4）175-200mm internal micrometerThe support position should be correct during measurement. The deformation of the large-size inner diameter ruler due to gravity after elongation involves form and position errors such as straightness, parallelism, and perpendicularity. The magnitude of its stiffness can be reflected in the 'natural deflection'. Theoretical and experimental results indicate that the stiffness determined by the cross-sectional shape of the workpiece has a significant impact on the gravity deformation after support. Although the length L of inner diameter rulers with different cross-sectional shapes is the same, when supported at (2/9) L, the measured value error of the inner diameter ruler can meet the requirements. But if the support points are slightly different, the straightness change value will be larger. So in the standard, the change in straightness when the support position is moved to the maximum support distance position is called "natural deflection". To ensure rigidity, it is stipulated in Chinese standards that the support point of the inner diameter ruler should be at (2/9) L and at a distance of 200 mm from the end face, which means that the variation during measurement should be minimized. And check the inner diameter ruler every 90 degrees of rotation
Once tested, the indication error should not exceed the requirement.