The Introduction of Micrometer

The structure of the micrometer

Generally speaking, a mechanical micrometer consists of the following parts:

frame, anvil, spindle, clamp, sleeve, thimble, ratchet stop.

Principle

The micrometer is made on the basis of the principle of spiral amplification, that is, the screw rotates in the nut for a week, and the screw moves forward or backward along the axis of rotation for a distance of pitch. Therefore, the small distance moved along the axis can be represented by the reading on the circumference. Screw micrometer precision thread pitch is 0.5mm, the movable scale has 50 equal scale, the movable scale rotates one week, the micrometer screw can advance or retreat 0.5mm, so the rotation of each small scale, equivalent to the micrometer screw forward or push back 0.5/50=0.01mm. It can be seen that each small fraction of the movable scale represents 0.01mm, so the spiral micrometer can be accurate to 0.01mm.

During the measurement, when the anvil and the micrometer screw are close together, if the zero point of the movable scale coincides with the zero point of the fixed scale, unscrew the micrometer screw, and make the surface of the anvil and the micrometer screw just touch the two sides of the length to be measured. At the end, be careful not to use force to rotate or the measurement will be inaccurate. When the measuring surface is touched immediately, slowly rotate the ratchet handle on the left and right sides until the sound is heard, then the distance that the micrometer screw moves to the right is the measured length. The whole millimeter of this distance is read from the fixed scale, and the fractional part is read from the movable scale.

How to operate?

1) Check the zero point before use:

Slowly turn the fine-tuning knob to make the measuring rod and measuring anvil contact until the ratchet makes a sound. At this time, the zero cut line on the active sleeve should be in line with the reference line on the fixed sleeve, otherwise there will be zero error.

2) Hold the ruler with the left hand, turn the coarse adjustment knob with the right hand to make the distance between the measuring rod and the measuring anvil slightly larger than the measured object, put the measured object, turn the protection knob to clamp the measured object, until the ratchet makes a sound, flip the fixed knob to make the measuring rod fixed after reading. The final reading result is fixed scale + half scale + movable scale + estimate reading

How to Maintain?

1. Check whether the zero line is accurate;

2. The workpiece should be wiped clean when measuring;

3. When the workpiece is large, it should be measured on the V-shaped iron or flat plate;

4. Wipe the measuring rod and anvil base before measurement;

5. Ratchet device is required when twisting the active sleeve;

6. Do not loosen the back cover to avoid changing the zero line;

7. Do not add ordinary oil between the fixed sleeve and the movable sleeve;

8. Wipe with oil after using, put in a special box and place in a dry place.