Among the gold cutting equipment used in a factory, there is a M1083A centerless cylindrical grinding machine produced by Haining Machine Tool Plant. The equipment is characterized by good rigidity, high production efficiency, good equipment performance, and can meet the needs of mass production. The grinding wheel and the front and rear bearings of the guide wheel main shaft adopt the membrane feedback static pressure bearing, and the bearing has a symmetrical structure of four oil chambers. The equipment recently appeared in the grinding wheel spindle hydrostatic bearing vice research and death, we have successfully repaired it. The following is a summary of the repair process of the hydrostatic bearing by combining the repair process with the cause of equipment failure. Fault reason analysis The grinding wheel spindle (grinding wheel spindle) bearing grinding causes mainly in two aspects: the first is the blockage of the oil pumping oil passage: the second is the blockage of the main oil passage entering the bearing oil chamber. These two reasons will directly lead to insufficient lubricant oil or insufficient oil pressure to enter the bearing oil chamber, which will cause the bearing pair to break out when the grinding wheel spindle is started.
The blockage of the oil supply circuit is mainly at the oil filter. M1083A has a triple oil filter on the oil supply road, especially the fine filter is easy to be blocked or the filter paper melts, causing the oil supply pressure to drop, the oil quantity is insufficient, the oil pressure is too low, and the spindle starter electrical interlock system fails, resulting in static The pressure bearing vice researched and died.
The oil passage blockage into the bearing oil chamber is mainly at the gap of the membrane feedback throttle valve. When the gap is severely blocked, the amount of oil entering the oil chamber is small, the oil pressure is very low, the spindle does not float well in the bearing, and if the grinding wheel is turned, it will not move or be heavy. The main shaft also causes the hydrostatic bearing to die.
1.2-105mm and bearing fit clearance 0.055 ~ 0.060mm2.2-? 105mm ovality, taper tolerance 0.002mmM1083A wheel frame spindle sketch M1083A wheel frame spindle parts as shown on the right. 2Remediation process After we removed the grinding wheel spindle, we found that the fault was mainly in the front bearing of the main shaft, and the rear bearing had no obvious grinding marks. First, we use the micrometer to accurately measure the front journal of the spindle. The actual size is 105-0.008-0.007mm. The inner diameter of the bearing is measured by the inner diameter dial gauge to be 105+0.048+0.051mm. The clearance requirement of the static pressure bearing pair is 0.006D (D is the nominal size of the spindle journal), the M1083A spindle journal D=105mm, and the technical requirements of the fit clearance should be 0.063mm. The matching clearance required by the design is 0.055~0.060mm. After the actual measurement size, it can basically meet the requirements of the matching clearance between the main shaft and the bearing. The roundness error of the spindle journal is 0.001mm, which meets the tolerance of 0.002mm roundness required by the drawings, thus ensuring the rotation precision and rigidity of the spindle parts of the equipment. It can be seen from the removed spindle that there is no obvious scar on the surface of the spindle journal. We polished the surface of the spindle journal on the C630-1 lathe to make the surface reach Ra0.8μm. The journal is re-measured and measures 105-0.010-0.008 mm. In addition, if there is obvious scratch on the surface of the spindle journal, the spindle journal must be finely ground to ensure the surface roughness: if the journal becomes smaller after grinding, the clearance between the spindle and the bearing cannot be met, then it must be The spindle journal is reliably plated to ensure that the matching clearance of the spindle-bearing pair meets the technical requirements, otherwise the rigidity and normal operation of the equipment will be seriously affected.
Check the inner hole of the bearing, and find that there are obvious friction marks on the front bearing hole, and the precision of the main shaft journal and the like are basically within the tolerance range, and the excessive tolerance of the main shaft is excluded. At the same time, check the lubricating oil road and find that the oil circuit is seriously blocked. After the spindle journal polishing reaches the required surface roughness, the repair of the bearing bore is more complicated, difficult to operate, and the accuracy is not guaranteed. We first design a diameter of 105+0.038+0.040mm test mandrel according to the spindle journal?105-0.010-0.008mm size and the required clearance between the main shaft and the bearing 0.063mm, the taper and roundness tolerance It is 0.002mm, as the final inspection tool, at the same time, the design and production of the 105+0.038+0.040mm mandrel can be smoothly inserted into the bearing inner hole and the contact between the inner hole of the bearing and the inner hole of the bearing is checked with the powder. carry out. Finally, use an internal diameter dial gauge to accurately verify the bore size of the bearing.
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