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As a material classification and separation equipment, vibrating screen has a wide range of applications. Its working principle is that under the action of the exciter, the material on the screen surface of the vibrating screen is continuously loosened, layered, and sifted through, and the material smaller than the screen hole size The material becomes undersize. The exciter is the core component of vibrating screening.
The commonly used exciters for vibrating screens mainly include electromagnetic exciters, vibration motors, self-synchronizing exciters, forced synchronizing exciters, etc. The latter three belong to inertial exciters. Now let's talk about it in detail.
The vibration exciter only acts on the screen surface, and the screen box does not participate in the vibration, which effectively reduces the vibration quality of the screen machine, improves the reliability of the screen machine, and reduces the energy consumption.
Electromagnetic vibration exciter is mainly used on light vibrating screens for dehydration of materials. In the coal washing and processing industry, the electromagnetic high-frequency screen taps the screen at a frequency of 50Hz, which effectively solves the problem of hole blocking and improves the dehydration efficiency.
An eccentric block is installed on the output shaft, and a certain centrifugal force is generated when the eccentric block rotates. The vibration motor is installed on the drive beam, and the vibrating screen can realize linear vibration or circular vibration by adopting a reasonable arrangement. The excitation force can be adjusted steplessly just by adjusting the included angle of the eccentric block. It has simple structure, long service life, stable operation and convenient maintenance.
However, due to the limited exciting force of the vibrating motor (2.5-300kn), it can only be used on small vibrating screens, which are generally used for vibrating screens with a vibration mass not greater than 4000kg.
Compared with ordinary vibration motors, the motor bottom plate is omitted, and the motor is directly installed on the side plate of the vibrating screen. Generally, two or more sets of the same type are connected in series to form a set of excitation sources, which can make the vibrating screen realize circular or linear motion.
Compared with the traditional eccentric block vibrating screen, the driving device is reduced, the occupied space is small, the whole machine is simple in structure, and the operating cost is low. It only needs to add grease to the motor bearing regularly.
Because the side plate vibration motor has the above advantages, it has gradually become an ideal excitation source for large-scale vibrating screens, heavy-duty vibrating feeders (or bar feeders) and other equipment.
The self-synchronizing vibration exciter generates the excitation force in the same way as the vibration motor, and the installation method is similar to the side plate vibration motor. The structure is shown in the following figure. Two sets of vibrators are distributed along the width direction of the vibrating screen and fixed on the side plates on both sides with bolts. The middle is connected in series with the transmission shaft, and the flexible coupling is connected with the motor on one side to form a series of vibrators, which can realize the movement of the vibrating screen.
Two motors are used to drive two series exciters, which can meet the stable conditions of synchronous operation under certain conditions and realize the stable linear operation of vibrating screen. Therefore, it is called self-synchronizing exciter.
This type of exciter can be used as the excitation source for medium and small circular vibrating screens and linear vibrating screens. The exciting force is transmitted to the whole screen machine through the side plate, and the stiffness of the side plate is just low for the whole screen machine, which will cause the overall elastic deformation of the screen machine to be too large or uneven, affecting the reliability.
For longer lengths (over 7m) or large vibrating screens, self-synchronizing exciters should not be used. In addition, the vibration amplitude of the shaker driven by the shaker sometimes increases significantly when the vehicle is stopped to pass the resonance zone, which is another disadvantage of this type of shaker.
The most obvious feature of the exciter is that a pair of gear transmissions arranged on the driving shaft and the driven shaft are used to realize the synchronous and anisotropic rotation of the eccentric blocks on the main and driven shafts. excitation force in the direction.
Compared with self-synchronized shakers, forced-synchronized shakers have many advantages:
(1) One vibration exciter can generate excitation force in a single direction, with compact structure, concentrated lubrication, light weight, and high box body strength and rigidity;
(2) Adopt one pair of helical gears with large helix angle, which can strictly ensure the synchronization of the eccentric blocks on the main and driven shafts, with strong bearing capacity, large excitation force, stable operation and low noise;
(3) The exciter is installed on the driving beam, and the exciting force is uniformly transmitted to the entire vibrating screen through the driving beam with high rigidity, and the elastic deformation of the vibrating screen is small, which is beneficial to improve its structural reliability;
(4) The exciter is easy to realize standardization, serialization and generalization, which is beneficial to industrial production and is the development trend of the exciter in the future.
Forced synchronous vibration exciter is mainly used for large linear vibrating screen, banana screen, relaxation screen, etc.
At present, vibrating screen has been widely used in coal, metallurgy, chemical industry, construction, mining and other industries. As the core component of vibrating screen, vibration exciter has a very important influence. I hope the above analysis of common vibration exciters will provide some help for your selection and design.
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