The vibrating screens have many types, basically most of them have the same shape. But their components which make the vibrating screen work and working principle are different. Generally speaking, the vibrating screen has different types, such as eccentric vibrating screen, inertia vibrating screen, Single-deck vibrating screen and so on. And next I will introduce a common type -- eccentric vibrating screen.
The eccentric vibrating screen relies on the high-speed rotation of the eccentric drive shaft vibration to work. So it is called eccentric vibrating screen and it is shown in figure 2-21.
(1)The structure of eccentric vibrating screen:
The eccentric vibrating screen consists of screen box, screen mesh, vibrator and under frame. It adopts cylinder eccentric shaft vibration exciter and eccentric block to adjust the amplitude. The vibrator is installed on the sideboard of the screen box, and driven by the motor through belts. It generates centrifugal inertial force to make the screen box vibrates. The sideboard of the screen is made of high quality steel. The sideboard beam and vibration exciter are connected by high strength bolt or ring-shaped rivet.
(2)The working process and principle of eccentric vibrating screen:
When the eccentric vibrating screen works, the eccentric shaft rotates constantly. The screen is rising when the eccentric arm moves up, the materials on the screen being thrown around and loose. The screen is falling when the eccentric arm moves down, the thrown materials falling down to the screen. After repeated toss, the materials meeting a criterion can go through the screen, and the materials falling short discharge the screen by the end of the screen. So achieve the aim to screen the materials according to the different size of materials.
The eccentric vibrating screen bears the inertia force in the working process. In order to protect it, it is equipped with balances. The movement direction of the balances is opposite to the screen's, and the inertia force produced by the balances, the magnitude is same with the screen's, the direction is opposite to the screen's, which ensures the stable and reliable work of the eccentric vibrating screen. If it is necessary, it can adjust the distance between the balances and eccentric shaft to meet the demand.
The eccentric vibrating screen works as rigid vibration. Although the amplitude of the screen is not changing as load changing, it will produce strong vibration while it works, which do harm to the machinery and buildings. Therefore, it is rarely used in the new processing plant.
