The working principle of internal micrometer

The inner diameter micrometer is made according to the principle of spiral enlargement, that is, when the screw rotates once in the nut, the screw advances or retreats along the axis of rotation for a distance of one pitch. Therefore, the small distance moved along the axis can be expressed by the readings on the circumference. The screw pitch of the precision thread of the screw micrometer is 0.5mm, the movable scale has 50 equal scales, the movable scale rotates one circle, the micrometer screw can be forward or backward 0.5mm, so rotating each small division is equivalent to measuring The micro screw advances or pushes back by 0.5/50=0.01mm. It can be seen that each small division of the movable scale represents 0.01mm, so the screw micrometer can be accurate to 0.01mm. Since it can be estimated to read one more digit, it can be read to the millimeter of millimeter, so it is also called micrometer.

When measuring, when the measuring 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, screw out the micrometer screw, and make the surface of the measuring anvil and the micrometer screw just touch the two sides of the length to be measured. Note that you cannot use force to rotate or the measurement will be inaccurate. When you touch the measuring surface, slowly rotate the ratchet knobs on the left and right sides until you hear a clicking sound. Then the distance that the micrometer screw moves to the right is the measured length. The whole millimeter of this distance is read on the fixed scale, and the decimal part is read on the movable scale. The structure of the spiral micrometer.