After choosing the right micrometer, it is also very necessary to use the micrometer correctly, which will directly
affect the accuracy and reliability of the measurement results. In the last small class, we learned about the key points
of measurement of internal micrometers, and today we will learn the key points of attention in the process of measuring
the inner size of the internal micrometers.
Three-point inner micrometer (6-1000mm) and two-point inner micrometer (2-6mm) are self-centering working principles
to achieve precise measurement of hole or blind hole size.
The two-point measuring head is mainly suitable for precise measurement of small holes (2-6mm).
The three-point (two-point) internal micrometer probe is driven by a cone that converts the measurement
in the Y direction into the measurement reading in the X direction.
Large stroke (100mm) and large measuring range (200-1000mm) realize the precise measurement of large bore size.
The measuring jaw of this kind of micrometer is interchangeable, according to different measuring ranges, each ruler
is equipped with 3 groups (200-500mm) or 7 groups (200-1000mm) of interchangeable measuring jaws, and the
high-precision replaceable jaw ensures that after the starting value of the ring gauge calibration (Φ200mm) is used,
the measuring jaw does not need to be zeroed again after replacement.
Other precautions for the use of three-point inner diameter micrometer:
1. Force measurement:
When using the force measurement device, the force measurement should be kept stable and the impact
should be avoided.
2. Proofreading starting value:
When using the force measuring device to calibrate the starting value of the micrometer, it should be repeated
4-5 times, and the workpiece can be measured only after the reading is stable.
3. Measurement Readings:
When measuring readings, the use of the force measurement device should be consistent with the use of
the force measurement when calibrating the starting value of the micrometer.
The three-point inner micrometer has the characteristics of self-centering. When measuring, the measuring head
of the micrometer should be in full contact with the inner hole, that is, the micrometer should not shake significantly
relative to the inner hole, and the maximum value measured at this time is the size of the inner hole. The solid line
in the figure shows the correct measurement orientation, otherwise (shown by the dotted line) will result
in measurement errors due to α angles.
When using a three-point internal micrometer to measure the blind hole, it should be ensured that the depth size
b of the blind hole to be measured is not less than 1/2 of the length of the three-point inner diameter micrometer
measuring jaw B.
