How to install needle roller bearings
1. Install fully loaded needle roller bearings, generally using auxiliary sleeves. The auxiliary roller or auxiliary sleeve will hold the needle from falling out, and the journal will lift the needle with its own chamfering. As the needle bearing moves inward slowly on the journal, the auxiliary roller or auxiliary sleeve will slowly withdraw until it is installed in the working position. The outer diameter of auxiliary roller and auxiliary sleeve should be 0.1-0.3mm smaller than the shaft diameter.
2. Needle roller bearings can also be installed in this way, that is, the outer diameter of the auxiliary sleeve is coated with a thin layer of lubricating oil, set into the bearing outer ring, so that the auxiliary sleeve and the bearing outer ring form a ring hole, and then the needle roller is installed in the ring hole. After installing the rolling needle, push the auxiliary sleeve out with the working shaft.
3. For needle roller bearings without inner ring or outer ring, when installing, the rolling surface of the shaft or shell hole can be coated with a thin layer of grease, and the needle can be attached to the grease on the installation part in turn. There should be a gap when sticking the last needle roller, and the size of the gap should be 0.5mm on the circumference of the needle roller bearing.
4. For needle roller bearings with only stamping outer ring, because the outer ring wall is very thin, do not use hand hammer to install, but use press to press in. Because the pressure is not uniform when the hand hammer is beating, it is easy to cause local deformation of the outer ring of the needle roller bearing.
Points needing attention for needle roller bearing installation
Bearing clearance refers to the maximum flow momentum of the other ring along the radial or axial direction when one ring is fixed, so clearance is divided into radial clearance and axial clearance. When the movable needle roller bearings are assembled, the clearance should not be too large or too small. If the clearance is too large, the number of movable bodies under load at the same time will be reduced, and the load of a single movable body will be increased, thus reducing the rotation accuracy of bearings and reducing the service life; Too small clearance will increase the friction, increase the heat generated, aggravate the wear, also can reduce the service life of bearings. Therefore, the clearance of bearings should be strictly controlled and adjusted when they are assembled.
The reasons for high bearing temperature are: lubricating oil quality does not meet the requirements or deterioration, lubricating oil viscosity is too high; The assembly of the mechanism is too tight (insufficient clearance); Bearing assembly is too tight; The bearing seat ring rotates on the shaft or in the shell; Excessive load; Bearing cage or rolling body fracture, etc.
1, the roundness of the shaft and the seat hole and the perpendicularity of the shoulder should be required according to the corresponding accuracy of the bearing.
2. It is necessary to accurately calculate both the interference amount of rotating ferrule fit and the appropriate fit amount of fixed ferrule fit. The burning interference amount of the rotating ring should be small within the possible range. As long as the influence of thermal expansion at the working temperature and centrifugal force at the highest speed is ensured, peristalsis or sliding of the tightly fitted surface will not be caused. According to the size of the working load and bearing size, the fixed ring selects a very small gap fit or interference fit, too loose or too tight is not good for maintaining the original accurate shape.
3. If needle roller bearings are operated at high speed and the working temperature is high, special attention should be paid to the fit of rotating rings should not be too loose to prevent eccentric vibration, and the fit of fixed rings should not be cleared to prevent deformation and vibration of rings under load.
Rolling bearings are allowed to have slight running sound in the work. If the sound is too large or there is abnormal noise or crash, it indicates that the bearing has failure.
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