Graphical micrometer reading method, master the use of micrometer

The micrometer has become a micrometer spiral measuring tool. It is a kind of micrometer measuring tool that uses the motion principle of the screw pair to measure and read. The micrometer is one of the most commonly used precision measuring tools in the measurement of machining, hardware processing, and electronics industries. Its accuracy It is higher than the vernier caliper and can be divided into inner diameter micrometer, outer diameter micrometer, depth micrometer and special thread micrometer for measuring the pitch diameter of thread and common normal micrometer for measuring the length of gear common normal. The measurement accuracy of the micrometer is 0.01mm. The outer diameter micrometer is a commonly used measuring tool in production. It is mainly used to measure the outer dimensions of the workpiece such as length, width, thickness and outer diameter. Its measuring accuracy is 0.01mm, and its measuring range is divided into units of 25mm. Commonly used outside diameter micrometers have specifications such as 025mm, 2550mm, 5075mm, 75-100mm and 100-125mm. (1) Structure of outside micrometer: as shown in the figure. Figure: Structure of outside micrometer (2) Measuring principle of outside micrometer: The pitch of the thread on the micrometer screw is 0.5mm. When the micrometer cylinder rotates one circle, the micrometer screw axially moves 0.5mm, and the fixed sleeve is engraved The scale line with a gap of 0.5mm, there are 50 grids evenly engraved on the circumference of the differential curve. Therefore, when the micrometer cylinder rotates by one division, the micrometer screw will move 0.5/50u003d0.01mm, that is, the accuracy is 0.01mm. (3) The reading method of the outer diameter micrometer: first read the integer millimeters and half millimeters of the engraved line exposed on the fixed sleeve. Look at which scribe line of the microtube is aligned with the reference line of the same sleeve, and read the decimal part less than half a millimeter. Finally, the two readings are added together to obtain the measured size of the workpiece. As shown in the figure are two examples of the measurement results of outside micrometers. Figure: Example of the measurement results of the outer diameter micrometer Figure: Example of the measurement results of the outer micrometer (4) The use method and precautions of the micrometer According to the characteristics, size and accuracy requirements of the workpiece to be tested, select the appropriate type, measurement range and graduation value. The general measuring range is 25mm. If you want to measure the size of 20±0.03, you can choose a micrometer of 0-25mm. Before measuring, wipe the two probes of the micrometer first and then perform zero calibration. When measuring, the measured workpiece and the micrometer must be aligned to ensure the accuracy of the measurement position. When using a micrometer, first adjust the micrometer tube to make its opening slightly larger than the measured size. When measuring, you can turn the micrometer tube first. When the micrometer screw is about to touch the surface of the workpiece, turn the ratchet wheel to measure the anvil, the end face of the micrometer screw, and the surface of the workpiece. When the surface of the workpiece is about to be in contact, the force measuring device should be rotated, and it will stop when the squeaking sound is heard, and the micrometer tube cannot be rotated slowly. When reading, you must face the engraved line, look at the aligned engraved line, and read correctly; pay special attention to the position of the engraved line below the center line on the fixed casing to prevent misreading 0.5 mm. It is strictly forbidden to measure on the rough surface of the workpiece, the moving workpiece or the workpiece with high temperature to prevent damage to the precision of the micrometer and affect the measurement accuracy. After use, wipe off the oil, put it in a professional box, and put it in a dry place. (5) Inside diameter micrometer: It can be used to measure the aperture of 5～30mm, and the graduation value is 0.01mm. The engraved line of this type of micrometer is opposite to the outer diameter micrometer. When the micrometer tube is rotated clockwise, the movable pawl moves to the right and the measured value increases. Due to the structural design, its measurement accuracy is lower than other types of micrometers. As shown below. Previous post: How does a fitter draw a line? It's very simple after learning the method