Calibration problem analysis and repair methods of micrometer

Micrometer verification problem of the 2019 - analysis and repair methods 01 - 10 yi-fan zhang abstract: according to the micrometer verification regulations, the verification of the unqualified item and analyze the problems in the actual use, provide the corresponding repairing methods, improve the accuracy value of micrometer, in order to meet the test requirements. Key words: measurement; Micrometer; Verification; Micrometer class of error of measuring tool is also called the micrometer measuring tool, has the characteristic such as high accuracy, simple operation, widely used in the production, life, scientific research, business and other fields. To ensure measurement accuracy, micrometer must, in accordance with the verification regulations, regularly test, for the common problems in the test project, according to the practical experience, gives corresponding repair method, ensure the accuracy of the measurement data and results. 1 field verification and repair requirements 1) The scene environment. Micrometer strict verification repair environment, need to temperature control device, temperature 20 & plusmn; 1 ℃, relative humidity less than 60 rh. Light, clean room ventilating, take measures should not be up dust, ash, without clean room is difficult to grind out the surface of the high precision, at the same time, to stay away from the source, magnetic source, corrosive substances. 2) Measuring tool. Measuring tool should first cleaning, derusting, measuring surface using silk scrub clean gasoline. 8 hours in the testing environment temperature, the operation is placed in a solid, level of work table. 3) Personnel operation. Check repair gloves should be worn to prevent hand sweat, temperature influence on the measuring tool. Test the same measuring time shoulds not be more than half an hour, the repaired measuring tool should also be constant temperature before test. 2 micrometer micrometer repair repair order first to arrange order, in accordance with the interaction relationship between the damage and repair projects. Under normal circumstances, the repair project for repair after the project completes the premise of security, after the repair can't repair has qualified the impact of the results of the project. Generally deal with the appearance of the micrometer cleaning, derusting, ruled out feet body obvious damage such as deformation, screw stuck, after verification clear project need to be repaired. Interaction of each structure repair first, including micrometer lever, locking device, differential cylinder friction, arch deformation, etc. Then to repair, axial channeling dynamic load, radial swing and rod position is not fixed to repair, required micrometer screw axial channeling move and radial run-out must be within the prescribed scope. Before grinding measuring surface flatness, parallel to the offline, and zero repair, in the final analysis and repair error value. 3 repair method of the micrometer screw up verification when the error of plus or minus value change, may be caused by a micrometer screw axial channeling move. If the lock nut still cannot eliminate axial channeling move, need grinding screw, eliminate the phenomenon of uneven. In general grinding screw and repair the error value was conducted at the same time, should know the situation of error before grinding, overall consideration grinding amount. Micrometer screw radial shaking is caused by the screw impact wear, light hole enlargement, or use for a long time due to a range. When repair line repair polished rod, the total length of the difference between the outside diameter does not exceed 0. 005 mm, increase diameter available plating method. After polished rod can repair the light hole, shrinkage cavity by punch, rushed over to try again, reduce the gap between rod and light hole. 4 plane degree and parallel degree of judgment and repair optical flat, block gauge, blade feet verification flatness or parallel unqualified need to grind measuring surface, fan-shaped reflection method is used, to light the fan formed in the surface of the definition and the location of the accumulation point inspection grinding in measuring the plane degree and parallel degree. Make sure the parallelism of micrometer differ when grinding, with parallel first is the location of the maximum linear reciprocating trajectory grinding mill; For fixed measuring one end face or micrometer screw surface is not perpendicular situation, both sides parallel difference is bigger, can be put in the parallel degree of good lubrication, need put abrasives abrasive surface, so that we can improve the grinding efficiency. When parallel grinding is good, then use four grinding mill grind after each rotation, trajectory evenly across the surface, to prevent the collapse edge or convex. Use 2 - each mill To change another piece after 3 minutes, four mill grinding according to the situation after it is change the finer abrasive grit. When the fan is clear, centered accumulation point, can be polished to mirror, verification again. When grinding, should keep the micrometer to measure surface parallel to mill, force uniform, straight line reciprocating movement, when pressing forward the slower, return without pressure, because too fast will generate heat affect the planarity gage block. Pay attention to during the process of grinding measuring tool surface, switching, to ensure that two face milling time are equal in number, such as after the repair result is not ideal, cooling grinding again after 15 minutes. Five calibration and repair of error of the comprehensive reflection of error of micrometer precision, in micrometer repair order, after exclusion of all other structural defects, considering the differential screw wear of the error value. Worn screw position, pitch, negative, of error of ground zero of the screw part; When positive out-of-tolerance of error of corresponding leadscrew grinding error. On the show all positive of error, according to the size of error of indication, grinding to the screw corresponding parts, the location of the great error in many research; On the show were negative of error, show zero corresponding to the screw thread to wear less than other around coal face, for zero corresponding to the leadscrew grinding; If each point error value is negative, first of all, according to the absolute value of the largest negative value to determine the zero error of grinding, grinding and then adjust the zero calibration again, every point error to positive change, values determine the second point grinding amount to repair again.