Precautions for the use of the most popular measur

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Precautions for the use of common measuring instruments

select appropriate measuring instruments for measurement according to the selection principle of measuring instruments. The measurement of measuring instruments should follow the maintenance, overhaul and identification plan of measuring instruments to ensure the accuracy, sensitivity and accuracy of the used measuring instruments. For the correct use of measuring instruments, please refer to the instruction manual or relevant reference materials, handle them with care, keep them clean, rust proof, vibration proof, and store them reasonably

I. flat plate 1. Steel flat plate is generally used for cold setting out or template trimming; In addition to the use of steel plates, cast iron plates can be used as grinding tools after sanding; The marble plate does not need to be coated with antirust grease, and is less affected by temperature, but it is easy to deform when the humidity is high

level 2, 0, 1 and 2 plates are generally used for inspection, and level 3 plates are generally used for scribing

3. The flat plate is placed stably. Generally, three supporting points are used to adjust the horizontal plane. The additional supporting points of the large flat plate must be leveled and stabilized, but the level must not be destroyed, and the force must be uniform, so as to reduce the self weight and shape

4. The flat plate shall not be worn too much due to frequent local use until the sample has penetrating cracks, and the influence of heat source and acid-base corrosion shall be avoided during use

5. The flat plate should not bear impact, heavy pressure, or long-term stacking of items

II. Template straightedge and leveling ruler 1. Template straightedge shall not be collided during use, and the integrity of edges shall be ensured. Hold the insulation board in hand to avoid temperature affecting the accuracy and rusting

2. Before measurement, the measuring surface of the ruler should be checked to ensure that there are no scratches, bumps, rust and other defects. The surface should be clean and bright

3. The working surface of the ruler shall be free of corrosion, spots, scales, pits, cracks and other defects. The ruler should be non-magnetic

4. Generally, the ruler with different accuracy should be selected according to different requirements

III. square ruler level 1, 00 and 0 straightness angle ruler are generally used to inspect precision measuring tools; Level 1 is used to inspect precision workpiece; Level 2 is used to inspect general workpieces

2. Before use, it should be checked that the monopoly of foreign enterprises on China's c/c composite brake pair segment market has been broken; And has obtained the PMA certificate of Airbus 320 Series c/c composite aircraft brake pair. Is the working surface and edge damaged. The left and right sides of the long side of the square and the upper and lower sides of the short side are the workpiece surface (i.e. inner and outer right angles). Wipe the working surface of the ruler and the working surface to be inspected

3. When using, place the straightness angle ruler against the working surface of the measured workpiece, and use the light gap method to identify whether the angle of the workpiece is correct. Pay attention to handle, lean against and handle with care to prevent bending and deformation

4. In order to obtain accurate measurement results, turn the straightness square 180 degrees and measure again. Take the arithmetic mean of the two readings as the measurement results, which can eliminate the deviation of the square itself

IV. universal angle ruler 1. Before use, wipe the universal angle ruler clean, and then check whether the interaction of various components moves smoothly and reliably, whether the reading after stopping does not move, and then set the zero position

2. During measurement, loosen the nut on the brake, move the main ruler seat for rough adjustment, and then turn the handle on the back of the vernier for fine adjustment until the two measuring surfaces of the angle ruler are in close contact with the working surface of the measured workpiece. Then tighten the nut on the brake to fix it, and then the reading can be carried out

3. After measurement, wash the universal angle ruler with gasoline, carefully dry it with clean gauze, apply antirust oil, and then put it into the box

v. vernier caliper 1. Before use, wipe the dust and oil on the measuring claw and the surface of the measured workpiece to avoid damaging the measuring claw surface of the vernier caliper and affecting the measurement accuracy. At the same time, check the interaction of various parts. For example, whether the ruler frame and inching device move flexibly, and whether the fastening screws can work

2. Check the zero position of the vernier caliper so that the two measuring claws of the vernier caliper fit closely. There should be no obvious light gap when observing with eyes. At the same time, observe whether the zero score line of the vernier is aligned with the zero score line of the ruler body, and whether the tail score line of the vernier is aligned with the corresponding score line of the ruler body. It is best to close the measuring claw of the vernier caliper three times and observe whether the readings are consistent. If the three readings are not zero, but the readings are exactly the same three times, you can write down this value and correct it during measurement

3. When using, it is necessary to grasp the pressure when the measuring claw surface contacts the working surface at the same time, which should not be too large or too small, just so that the measuring surface contacts the workpiece, and the measuring claw can slide freely along the workpiece surface at the same time,. Vernier caliper with micro motion device shall use micro motion device

4. When reading with the vernier caliper, hold the vernier caliper horizontally towards the light direction, so that the line of sight is perpendicular to the scale line read on the ruler as far as possible, so as to avoid reading error caused by the deflection of the line of sight. It is best to measure multiple times at the same position of the workpiece and take its average value

5. When measuring the external dimension, after reading, do not forcibly pull the downstream caliper from the measured workpiece, but open the measuring claw and take it out; After measuring the internal dimension reading, make the measuring claw slide along the center line of the hole to prevent deflection, otherwise the measuring claw will be worn, twisted, deformed or the ruler frame will move, affecting the measurement accuracy

6. The moving workpiece cannot be measured with a vernier caliper. In this way, the vernier caliper is easy to be seriously worn and prone to accidents

7. It is not allowed to drag back and forth on the workpiece with a vernier caliper instead of a caliper. When using the vernier caliper, do not strike it with the working force to prevent damage to the vernier caliper

8. Do not place the vernier caliper near a strong magnetic field (such as on the magnetic workbench of a grinder) to avoid magnetizing the vernier caliper and affecting its use

9. After use, the vernier caliper should be wiped clean and placed flat in a special box, especially the large-size vernier caliper. Pay attention to rust prevention and bending deformation of the main ruler

VI. height vernier caliper 1. Before use, check whether there are burrs or scratches on the working surface of the base, whether the working surface of the base and the flat plate for inspection are clean, whether the measuring claw is intact, whether it is fastened, etc

2. When moving the height ruler, hold the base and do not grasp the ruler body, otherwise it is easy to fall or deform the ruler body

3. When measuring the height, first stick the base of the height ruler to the flat plate, move the measuring claw of the ruler frame to make its end contact with the flat plate, and check whether the zero position of the height ruler is correct. Then, raise the measuring claw of the ruler frame to a size slightly larger than the measured workpiece, tighten the fastening screw of the inching device, rotate the inching nut to make the end of the measuring claw contact the measured working surface, and tighten the fastening screw on the ruler frame to read the measured height

4. When scribing, install the scribing measuring claw, adjust the ruler frame according to the height size of the required scribing, tighten the fastening screw of the inching device first, and then rotate the inching nut to make the height size accurately align with the size of the required scribing, and then fasten the ruler frame before scribing. When marking, the base should fit the platform and move smoothly

VII. Depth micrometer 1. The replaceable measuring rod tightened with screw will directly affect the indicated value due to different tightening degrees. Therefore, calibration must be carried out before use or after replacing the measuring rod

2. Before measurement, clean the measuring surface of the base plate and the measured surface of the workpiece, and remove burrs. The measured workpiece must have a certain surface roughness

3. During measurement, keep the bottom plate in close contact with the surface of the measured workpiece. The central axis of the measuring rod shall be perpendicular to the measuring surface of the measured workpiece

4. The end of the measuring rod is easy to wear, so it is necessary to often check whether the zero position is correct. The calibration of zero position can be carried out by using cylindrical calibration measuring tools or two gauge block assemblies with the same size

VIII. Outside micrometer 1. Before measurement, its zero position must be calibrated, which is commonly referred to as zero position. For micrometers with a measuring range of 0~25 mm, the two measuring surfaces should be angled when checking the zero position; When the measuring range is greater than 25mm, a measuring rod with a size of its lower limit shall be placed between the two measuring surfaces for measurement. To adjust the zero position, the edge on the differential cylinder must be perpendicular to the 0 line on the fixed sleeve, and the zero line on the differential cylinder must be aligned with the longitudinal scribed line on the fixed sleeve

2. Hold the heat insulation device with your hand when using it, otherwise it will increase the measurement error. In general, it should be noted that the outside micrometer and the measured work have the same temperature

3. When the two measuring surfaces of the micrometer will contact the workpiece, the force measuring device should be used instead of directly rotating the differential cylinder

4. The center line of the micrometer measuring shaft should be consistent with the measured length direction of the work, and should not be skewed

5. When the measuring surface of the micrometer is in contact with the measured work, the geometry of the work surface should be considered

6. When measuring the processed workpiece, the workpiece should be measured under static state, not when the workpiece is rotating or processing, otherwise it is easy to wear the measuring surface, twist the measuring rod, or even break

7. When adjusting the outside micrometer according to the measured size, turn the differential cylinder or force measuring device slowly, and do not hold the differential cylinder and swing or rotate the ruler frame, so as to deform the precision micrometer screw

IX. lever micrometer 1. Before measurement, first check the zero position of the differential cylinder and the zero position of the lever indicator. The MM lever micrometer can be calibrated directly by using the joint angle of two measuring surfaces, and the lever micrometer above 25 mm can be calibrated with grade 0 adjusting rod or 4 equal measuring blocks

2. Direct measurement with a lever micrometer is to place the workpiece correctly between the anvil of the lever micrometer and the micrometer screw, adjust the differential cylinder so that the pointer on the dial has an appropriate indication, and pull the fork several times. The indication must be stable. At this time, the actual size of the workpiece is the reading of the micrometer differential cylinder plus the reading on the dial. 3. The lever micrometer can be used as a standard for comparative measurement. Adjust the lever micrometer so that the pointer of the micrometer lever is at the zero position. After fastening the differential cylinder, read on the indicator, which can avoid the influence of the indication error of the differential cylinder and improve the measurement accuracy

4. For batch measurement, the indicated value of the lever micrometer should be adjusted according to the nominal size of the measured workpiece (using the gauge block), and then, according to the tolerance requirements, turn the adjusting screw of the tolerance zone finger rod to adjust the tolerance zone. During measurement, it is only necessary to observe whether the pointer is within the tolerance zone to determine whether the workpiece is qualified

5. When measuring the distance between curved surfaces or cutting edges, swing the lever micrometer or the measured workpiece and read at the return of the pointer

X. internal micrometer 1. When checking the zero position, use the certified standard ring gauge or the combination of gauge block and gauge block accessories. It is not suitable to choose the outer micrometer, otherwise its accuracy cannot be guaranteed

2. When measuring the internal dimension with an internal micrometer, it can only be measured according to the length of the measuring surface of the measuring claw

3. When measuring, the measuring position must be placed correctly. When measuring the hole, rotate the differential cylinder with a force measuring device to make the measuring claw contact the workpiece at the maximum position in the radial direction and at the minimum distance in the axial direction

4. It is not allowed to use the two measuring claws as the fixed caliper according to the inherent analysis, so as to avoid the accelerated wear of the measuring surface of the measuring claw

Xi. Inner diameter dial gauge and inner diameter dial gauge 1. Before measurement, select the measuring head of corresponding size according to the size of the measured workpiece, and adjust the zero position of the inner diameter dial gauge. After use, the zero position should also be adjusted in order to observe the change of the inner dial indicator

2. In the adjustment and measurement work, the probe of the inner diameter dial gauge should be connected with the ring gauge and the measured hole

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