In the last part, we introduced the first two factors. Here, we focus on the other three factors affect the bearing vibration in vibrating screen.
The Radial Internal Clearance Of Bearings
Too large or too small radial internal clearance will both cause great vibration of bearings. Too small radial internal clearance cause high-frequency vibration and too large radial internal clearance cause low-frequency vibration. Too large radial internal clearance will reduce the radial natural frequency of elastic system of bearings. It is easy to produce sympathetic vibration and cause large low-frequency vibration. This is because it will produce large accelerated speed at the impact point of rolling element and ferrule.
According to test and analysis, too large radial internal clearance will cause strong impact vibration of bearings. And if the radial internal clearance is too small, because the radial force is large, so the friction temperature rise is very fast, which will cause high temperature burn of bearings. Besides, the retainer will cause have large radial runout with the increasing of radial internal clearance, and then cause strong vibration.
The coordination of outer ring and the bearing hole will affect the transmission of vibration. The tight coordination will force the raceway deforms and accelerate the form error, leading to the vibration more serious. The loose coordination will make the oil film in the clearance produce antihunt action.
Friction And Lubrication
Bearings are the main vibration source that is difficult to control in vibrating screen. Since the vibrating screen works through strong excited force, so the bearings are under great radial force. In the operation process of vibrating screen, the strong excited force will cause the elastic vibration of bearings. If the bearings are with poor lubrication, it will have large friction, making the temperature rise of bearings very high.
In this case, the radial internal clearance decreases sharply, accelerating the friction and making the temperature rise increase further. So many manufacturers adopt large radial internal clearance in vibrating screens. But too large radial internal clearance reduces the radial natural frequency of bearings and increases the possibility of radial runout of rolling element. At the same time, the energy of impact ferrule will also increase in the runout process of rolling element, which will increase the vibration value of frequency components, causing strongly high-frequency vibration.