1 General situation of vibratory separator. Vibratory separator screen is mainly composed of screen box, drive device, screen frame, supporting frame and vibration damping devices. It uses the vertical motor as the excitation source, and the motor is equipped with eccentric weight hammer at the upper and lower ends. The eccentric mechanism is used to make the screen surface move in a uniform circular motion. Under the action of the circular motion of the screen body, the rotating motion of the motor is transformed into a horizontal, vertical and inclined three-dimensional motion, then pass the motion evenly to the screen surface. The mesh produces cutting motion on the powder material and automatic grading, which enables the material with smaller particle size to be sifted quickly. The larger size of the above material is moving towards the end of the discharge, moving rapidly towards the direction of discharge, until the discharge machine, complete the whole material screening. During the screening process, the bouncing elastic ball effectively prevents the material from blocking the screen hole. By adjusting the phase angle of the upper and lower end weights, the movement track of materials on the screen surface can be changed to meet the requirements of screening.

2 Problems and causes analyse of vibratory separator. At the initial stage of operation, the effect of the screen machine proved to be unsatisfactory.The main problems are that the mesh is easy to be torn, plugged and is not easy to clear out, and the screening efficiency is low. There are several reasons for these. First, the tension of the screen is not enough or uneven.Second, Incorrect steering of vibration motor.Third,material accumulation. Fourth, contains a large number of particles close to the separation point. Fifth,the material is spherical, static electricity or agglomeration will occur, mesh congestion is serious. Fourth hammer phase angle adjustment is not in place.
3 Improvement measures.
3.1 Change the screen paste process. When tension the screen mesh along the periphery of the grid, the force should be uniform, otherwise the tension of the screen mesh is uneven. In the use of the loose part is easy to heap material, and the entire screen surface stress uneven, the screen is easy to be torn, so we need to improve the pasting technology of the screen. After improvement, the labor intensity is greatly reduced in the bonding process of the mesh, and one person can put the hoop on the mesh frame. The tension of the screen is also very flexible. We can adjust the tension through the tightening hoop bolts, and the tension of the screen is also very uniform.
3.2 Change the screen clearing method. The vibratory separator mainly relies on the bouncing elastic ball to prevent the material from blocking the screen, so as to clear the mesh. However, the effect is not obvious in the process of use, and the bouncing height and strength of the ball are not easy to control, which is easy to cause damage to the screen. After the study, ultrasonic vibration is used instead of elastic ball to clean the screen, so as to achieve the purpose of efficient screening and cleaning the screen.
3.3 Adjust the angle of hammer. Adjusting the phase angle of the hammer can change the movement track and residence time of the material on the screen. It is proved by the test that the phase angle of the weight hammer is generally adjusted between 15 ° and 45°.
Through the improvement of the tension mode and clearing mode of the screen and the reasonable adjustment of the phase angle of the hammer, we can completely change the current situation of frequent breakage of the screen, which will effective improve the service life of screen and prolong the service life of vibratory separator.