First, analyze the cause of the fault
After analyzing the causes of the failure in the equipment, it was found that the surface of the journal part of the grinding wheel shaft in the surface grinder has longitudinal cracks, and the front and rear bearing appearances have no obvious defects, and the wear amount is not large. The grinding head is dismantled and tested. It was found that the grinding wheel shaft was curved, and only shallow longitudinal cracks were present in the journal portion. The outer cone flanges of the front and rear bearings are in good contact with the bearing housing bores, and the bearing bores are not significantly damaged. The hardware mechanical mold network Jinjitong hints that the main reason why the grinding head can not work is that the geometrical accuracy of the front and rear bearings changes, and the shape and size of the three oil wedges are inconsistent. Therefore, the plan to repair the repair is to repair the front and rear bearings and the hard chrome (0.02mm) repaired grinding wheel shaft.
Second, the combination of scraping and grinding to repair the bearing
Jinjitong proposes to repair the bearing by the combination of scraping and grinding. It not only scratches the front and rear bearings, but also enlarges the contact area by grinding and reduces the surface roughness. When scraping, it is lightly scraped and must not be scraped. The fish is scaly.
1. Install the front and rear bearings to the working position, and grind a cylindrical mandrel with a length of 400mm (55mm in diameter) according to the bearing hole. The degree of grinding is subject to the rotation. Apply a thin layer of red dan oil on the mandrel, insert the mandrel into the bearing, adjust the tightness of the front and rear bearings, turn the mandrel, and pull out the mandrel to make a light scratch point. This work must be repeated to achieve uniform and dense spots in the three rectangular strip contacts on the front and rear bearing inner surfaces. Then grind a cast iron grinding rod with a diameter of 0.02mm and a length of 400mm, which is coated with W5 chrome oxide paste. The front and rear bearings are simultaneously ground, and the front and rear bearings are tightened at any time and the end of the bearing is removed. Abrasives. After grinding, the contact surface of the bearing is a complete three rectangular contact strips, and finally the bearing housing is removed and carefully cleaned so that it does not have any impurities.
2. Install the front and rear bearings in place, and grind a cylindrical mandrel with a length of 350mm according to the bearing hole. The degree of fit with the inner hole of the bearing is suitable for the rigidity to penetrate. Adjust the front and rear bearings until the mandrel is difficult to rotate. During the adjustment process, the front and rear bearings should be alternated. Do not adjust one of them first and then adjust the Other. According to the mandrel diameter of 0.01mm, the grinding wheel shaft journal can be assembled after polishing.
3. Jinjitong prompts that the lubricating oil is added in order to carry out the dry running test before and after the grinding wheel, and finally the grinding test. After grinding, the front and rear bearings have three long rectangular contact faces with a width of 15 mm corresponding to the outer tapered flange. In order to further reduce the roughness of the bearing bore, we tried to polish it with toothpaste. No significant change was found in the final assembly accuracy of the inspection rods, ie the diameter was subtracted from 0.01 mm as the size of the wheel journal.
Third, the use of research and repair methods to repair bearings
1. The cast iron grinding rod with three 120mm lead forward and reverse spiral grooves is used for overall grinding to ensure the coaxiality of the front and rear bearings. The diameter of the grinding rod is reduced by 0.02 mm on the basis of tight cooperation with the front and rear bearings. The abrasive used is a blend of M28 alumina and kerosene. In order to make the front and rear bearings have the necessary adjustment margin, the front and rear bearings are gently pushed into the bearing housing by hand, and the adjusting nut is put on the assembly, and then the adjusting screw is tightened slightly.
2. The grinding head is placed in a vertical state during grinding. In order to facilitate the proper axial movement of the grinding rod during the grinding process and reduce the labor intensity, a hydraulic jack is placed directly under the grinding rod, and the grinding rod is supported by the steel ball. In order to center the hand-held force during the grinding process, a hand wheel device is attached to the upper end of the grinding rod.
Fourth, the precautions in the grinding process
Jinjitong prompts that the rotation direction of the grinding rod is consistent with the working rotation direction of the grinding wheel shaft. This is advantageous for the self-suction oil flow to form an oil wedge through the radial gap at work, thereby improving the running performance.
1. During the grinding process, the front and rear bearings should be continually adjusted (maintaining a certain hand) to improve the grinding efficiency and ensure the geometric accuracy of the bearing.
2. Remove excess abrasive at the end of the bearing at any time to avoid flares on the front and rear bearings.
3. After grinding for a certain period of time, extract the grinding rod, remove the abrasive in the grinding rod and the front and rear bearings, check the grinding effect and the damage of the grinding rod. If the grinding rod is damaged, it needs to be trimmed to ensure the front. The consistency of the rear bearing bore.
4. When making the final grinding, the abrasive should be as small as possible and the front and rear bearings should be properly tightened to ensure the final geometric accuracy of the front and rear bearings.
V. Summary
After the repair and assembly of the MM7132 surface grinder dynamic pressure bearing, the test was successful, and the grinding shaft, vibration and heat generation were solved, so that the equipment can be produced normally and safely. We believe that the key to repair quality is to ensure the coaxiality, cylindricity and better surface roughness of the front and rear bearings, so that the shape, size and thickness of the three oil wedges are as consistent as possible, and the most effective repair can be guaranteed. The process is the overall grinding of the front and rear bearings.
Http://news.chinawj.com.cn Submission:
kaiping aida sanitary ware technology co.,ltd , https://www.kpaidafaucets.com