How Do The Two Screen Frames of The Flip Flow Screen Move Relative To Each Other

Introduction

After mining, the ore needs to be screened and classified to facilitate subsequent beneficiation and smelting. Due to its double screen frame structure and the ingenious relative motion principle between the two screen frames, Flip flow screen can efficiently separate ores of different particle sizes, improve the beneficiation efficiency and reduce the production cost. Next, let’s analyze how the two sieve frames of the flip flow screen move relatively.

Structural Analysis of Flip flow screen

External main screen frame

The external main screen frame bears the load, supporting the weight of the entire flip flop screen and the impact of materials during the screening process. The outer screen frame is connected to the exciter. The strong and large vibration force generated by the exciter is transmitted to the entire screening system through the main screen frame. The main screen frame usually vibrates in a straight line or an ellipse. This vibration mode enables the material to move along a specific trajectory on the screen surface, achieving the transportation and initial screening of the material.

The amplitude of the main screen frame is relatively small. A smaller amplitude enables the material to move smoothly on the screen surface, ensuring the stability of the material during the conveying process, avoiding excessive jumping of the material and resulting in poor screening effect. At the same time, it reduces the wear and energy consumption of the equipment and extends the service life of the equipment.

Internal secondary screen frame

The internal secondary screen frame is mainly responsible for fixing the screen surface material and is usually made of polyurethane. It works in conjunction with the main screen frame to jointly complete the screening task. The movement trajectory of the secondary screen frame is similar to that of the main screen frame, but there are differences in the movement phase and amplitude. When the movement phases of the main screen frame and the auxiliary screen frame are opposite, the forces in opposite directions will cause the screen surface material to be strongly stretched and twisted, thereby generating high-frequency vibrations, which can effectively prevent the material from blocking the screen holes and improve the screening efficiency.

Screen surface material

Flip flow screen usually adopts flexible polyurethane material as the screen surface. The flexibility of the material enables it to easily adapt to various complex deformations during the relative movement of the two screen frames. When the movement directions and speeds of the main screen frame and the secondary screen frame are different, the polyurethane screen surface between them will be tightened and relaxed in a short period of time, forming periodic tension and relaxation movements. In the tensioned state, the screen surface material is stretched tightly, and the screen holes become more regular, which is conducive to the passage of materials through the screen. In a relaxed state, the material on the screen surface regains its elasticity and can shake off the material adhering to the screen holes, preventing the holes from being clogged.

The principle of relative motion of Two screen frames

Drive mode and connection

The main screen frame is usually driven by a motor through a belt or a coupling to directly drive the exciter. The strong vibration force generated by the exciter causes the main screen frame to vibrate in a straight line or ellipse. The driving of the secondary screen frame is usually achieved through elastic elements connected to the main screen frame and dedicated excitation devices to realize vibration. These elastic elements connect the main screen frame and the secondary screen frame together, and there is a certain relative motion between them.

The connection between the main screen frame and the secondary screen frame usually adopts high-strength rubber springs or metal springs as elastic connection elements, which can effectively transmit vibration force, and also buffer and absorb the impact force generated during the vibration process, reducing the wear and noise of the flip flow screen.

Phase and amplitude

When the vibration phases of the two screen frames are opposite, with one moving forward and the other backward, this opposite movement direction will cause the flexible screen surface material between them to be subjected to intense stretching and twisting.

Suppose the main screen frame moves upward at a certain moment, while the secondary screen frame moves downward. Due to the tensile effect, it can effectively prevent the material from blocking the screen holes, making it easier for the material to pass through the screen. When the movement directions of the main screen frame and the auxiliary screen frame change, the screen surface material will quickly relax and return to its original state.

If the amplitude of the main screen frame is small while that of the secondary screen frame is large, the high-frequency vibration of the secondary screen frame will cause more intense deformation of the screen surface material, enabling the material to jump and roll more actively on the screen surface and increasing the contact opportunities between the material and the screen holes.

Periodic tension and relaxation movements

When the screen surface is in a tensioned state, the screen holes are stretched more regularly and the size is relatively stable. When the material passes through the screen holes, it can pass through the screen more smoothly, reducing the retention and blockage of the material at the screen holes.

When the screen surface is in a relaxed state, the material of the screen surface regaining its elasticity, which can shake off the materials adhering to the screen holes, prevent the screen holes from being blocked, and make the movement of the materials on the screen surface more free, allowing them to jump and roll on the screen surface, increasing the probability of collision between the materials and the screen holes, and further improving the screening efficiency.

The performance of Flip flow screen

Relative acceleration

During the screening process of the Flip flow screen for coal, the relative motion between the main screen frame and the secondary screen frame generates a strong relative acceleration. The generation of the relative acceleration stems from the phase and amplitude differences of the two screen frames during the vibration process. When the motion phases of the main screen frame and the secondary screen frame are opposite, the relative velocity between them will increase instantaneously, thereby generating a relatively large relative acceleration.

The main screen frame moves upward while the secondary screen frame moves downward. The relative speed between the two is the superposition of their respective speeds, which causes the material to be subjected to intense impact and vibration. The interaction between the material and the screen surface is greatly enhanced, allowing the material to come into more thorough contact with the screen surface. More materials that meet the particle size requirements can quickly pass through the screen. Relative acceleration can also effectively break up material lumps, making the materials more evenly distributed on the screen surface, avoiding material accumulation and clogging, and further improving the screening efficiency.

Prevent hole blockage

In traditional screen machines, the movement of materials on the screen surface is relatively monotonous, and they are prone to accumulate at the screen holes. Especially when dealing with viscous materials, the phenomenon of hole blockage is more serious. The relative motion between the main screen frame and the secondary screen frame of the Flip flow screen causes the screen surface material to undergo periodic changes of tension and relaxation in a short period of time.

When the screen surface is in a tensioned state, the screen holes are stretched more regularly and the size is relatively stable. This enables the material to pass through the screen holes more smoothly and reduces the retention of material at the screen holes. When the screen surface is in a relaxed state, the screen surface material regains its elasticity and can shake off the materials adhering to the screen holes, preventing the screen holes from being clogged.

Material fluidization

During the working process of the Flip flow screen, due to the relative movement between the main screen frame and the secondary screen frame, the material is subjected to high-frequency vibration and impact on the screen surface, thus presenting a fluid-like state, that is, the material fluidization phenomenon.

When the material enters the screen surface, under the relative motion of the main screen frame and the auxiliary screen frame, the material is subjected to constantly changing forces. These forces reduce the friction between the materials, break the constraints between the particles, and the materials start to freely jump and roll on the screen surface. The fluidization of materials makes it easier for them to pass through the screen on the screen surface, and also enables the movement of materials on the screen surface to be smoother, reducing the residence time of materials on the screen surface and further enhancing the speed and efficiency of screening.

Conclusion

The principle of relative motion of the double screen frames of Flip flow screen: The external main screen frame bears the load and is driven by external vibration, while the internal secondary screen frame fixes the flexible polyurethane screen surface material. There are differences in the motion phase and amplitude between the two screen frames, achieving periodic tensioning and relaxation of the screen surface material. The relative motion generates a strong relative acceleration, effectively preventing the material from blocking the holes. Promote the fluidization of materials and enhance the screening efficiency.