Overview of vibrating screen frequency:
The determination of working frequency and amplitude The technological effect of vibrating screen is usually determined by the vibration intensity. Once the vibration intensity is determined, it is necessary to select a reasonable amplitude and frequency. The vibrating screen usually used for grading operation is generally low frequency and large amplitude; The vibrating screen used for dehydration and medium removal shall be of high frequency and small amplitude;Low frequency and large amplitude shall be selected for screening operation of small wet particle viscous materials.
Practice has proved that the working frequency of the vibrating screen should not be less than 700 r/min. Considering the different uses of different screens, the operating frequency of the screen is controlled at 800~900 r/min. When the vibration intensity is 4 and 4.5, the distribution of amplitude A and frequency n of the screen machine has a large difference.
Determination of vibration intensity:
The mechanical index is the ratio of the maximum acceleration and gravity acceleration of the screen box, i.e. K=A ω 2/gn. The larger the K value is, the greater the dynamic load on the machine is, which is more conducive to the improvement of the process indicators. However, the higher the value is, the greater the acceleration and inertial force will be, which will inevitably lead to the decline of the life of the screen machine.
Vibration direction angle and material moving speed along screen surface:
The determination of vibration direction angle is considered from the moving speed of materials along the screen surface, and the optimal vibration direction angle is related to the mechanical index. For materials difficult to screen or highly corrosive, direction angle β It should be large, and the direction angle of fragile materials should be small. Generally β= 35～50°。 The vibration direction angle of generally designed vibrating screen is 45 °.
Structural design of vibrating screen:
Vibrating screen is composed of screen box, vibrator, support device and transmission device.
Structure of vibrating screen box:
The screen box of the vibrating screen is the main working part of the screen machine, which supports the vibrator, transmits the exciting force and bears the impact of materials. The load characteristics require that the screen frame has sufficient strength, stiffness and good dynamic performance. The main components of the screen box of large screen machine are side plate, reinforcing beam, feeding and discharging end beam and cross beam.
The side plate is cut with a whole steel plate, and connected with the reinforcing rib and support through the high-strength torsional shear bolt rotary vibration screen, so that the side plate forms a spatial network structure. The whole side plate is free of any weld, thus avoiding the residual stress generated by hot working. The cross beam includes a driving beam and a lower cross beam for installing vibrators.
Considering the connection with the vibrator and side plate, the driving beam is welded with double I-shaped thick steel plate, which has good mechanical properties. The crossbeam is of OC structure with good rigidity, and the upper part is equipped with a sealing baffle. The baffle and the sealing part of the crossbeam have no bolt holes, which can prevent liquid from flowing into the sealing girder and causing corrosion and reduce the service life of the machine.
The stringer bracket is designed as an integral part without welding. The lining surface of the feed box and both sides of the screen box are paved with wear-resistant and corrosion-resistant materials to prevent wear and corrosion.