Reasons and Solutions for Strong Vibration of Vibrating Screen
1、 Eccentric vibration of exciter
The centrifugal force generated by the eccentric weight during the operation of the vibration exciter will bend the eccentric shaft, causing the relative deflection of the inner ring and outer ring of the bearing. The eccentricity will produce vibration caused by the frequency rotation and its harmonic frequencies.
Therefore, the inertia force and inertia couple generated during the operation will cause the dynamic reaction force and vibration of the bearing, damage the stable working state of the bearing and other parts, and generate high-frequency vibration. When the bearing vibration frequency of the vibrating screen exciter is the same as the natural frequency of a certain stage of elastic vibration of the equipment screen box, it will cause strong vibration of the screen box elastomer of the vibrating screen.
Both the drive shaft and driven shaft systems of the bearing have a resonance frequency of a certain value. If some exciting frequencies are close to the resonance frequency, resonance occurs. In addition, because of the existence of centrifugal inertial force in the eccentricity, bending vibration will occur. If the speed is close to the critical value, bending resonance will occur.
2、 Radial clearance of bearing
The bearing test results of the shale shaker show that too small or too large radial clearance will cause greater vibration of the bearing system. When the radial clearance is too small, it will cause high-frequency vibration; When the radial clearance is too large, it will cause low-frequency vibration.
If the radial clearance is too large, the radial natural frequency of the bearing elastic system will be reduced, and resonance will easily occur, which will produce large low-frequency vibration. Therefore, the radial clearance is large, which makes the bearing vibrate in the passband.
3、 Geometric accuracy of bearing
If the exciting force of the vibrating screen is too large, the bearing will bear very large radial force, so strong vibration will occur. When the raceway, especially the waviness on the surface of the rolling element, has a greater impact on the vibration of the bearing, the relative motion of the clearance between the rolling element and the cage and the rolling surface of the inner and outer rings will cause the vibration of the bearing. Therefore, to reduce the bearing vibration, the surface processing accuracy of the rolling element should be improved first.
4、 Bearing friction and lubrication
Bearing is the main vibration source that is difficult to control for the shale shaker. Since the shale shaker works by a large excitation force, the bearing will suffer a large radial force. If the lubrication is poor, there will be greater friction, which will make the bearing temperature rise too fast and too high, and the thermal expansion too large, which will significantly reduce the radial clearance, and then increase the friction, which will further increase the temperature.
5、 Fitting of outer ring and supporting hole
If the fit is tight, it will force the raceway to deform, increase the shape error, and lead to increased vibration. A loose fit can cause the oil film in the clearance to obstruct. When the material properties of the supporting holes of the outer ring and the bearing seat are quite different, especially when rubber damping rings are placed between them, vibration transmission will be restrained.