January, 2021 | Haiside

Common problems and solutions of vibrating screen exciter

2021-01-29/in News /by admin

Screening equipment is an important auxiliary equipment in mining, building materials, chemical industries and other industries. Its performance directly affects production capacity and technical and economic indicators. Therefore, it is very necessary to understand some common fault diagnosis and solutions of vibrating screens in production practice. This article shares the common problems of vibrating screen exciters, the main reasons and solutions for the cracking and deformation of the screen frame and side plates.

The exciter is the vibration source of the screen body. The amplitude can be adjusted by the counterweight. When the exciter is working, the centrifugal force generated by the eccentric mass is selected as the exciting force. When the biaxial exciter rotates synchronously, The screen box performs reciprocating linear vibration, and the materials are screened through the gap of the drying surface, and then the screening work of the product mine is completed.

The failure of vibrating screen exciter generally has the following situations:

1. Start under heavy load

Sudden shutdown due to production or other equipment failures makes the screen box full of minerals. If the exciter starts again under heavy load, it is very easy to cause damage to the universal coupling and other parts of the exciter.

Solution: Avoid restarting the vibrating screen under heavy load.

2. Damage to the damping system

If the damping spring fails or too much material under the screen, etc., the damping system will be uncoordinated and cause damage to the vibration exciter.

Solution: Check the damping spring regularly, and replace the springs that fail and deform in time. When replacing, replace all the damping springs at the same time as much as possible, and ensure that the stiffness of each group of springs before and after replacement is consistent.

In summary, there are two common problems with vibrating screen exciters and corresponding solutions. The vibrating screen exciter must strictly follow the corresponding operating instructions during the installation and use process to ensure the safe operation of the equipment.

How to adjust the vibration frequency of the vibrating screen

2021-01-29/in News /by admin

As we all know, the operation of the vibrating screen is inseparable from the vibrating motor. The vibrating screen is driven by a vibrating motor. The frequency of vibration depends on the speed of the vibration motor. The speed of the vibrating screen is reduced, or the reduction ratio of the transmission system is increased. Large, can reduce the vibration frequency of the vibrating screen. Similarly, by increasing the rotational speed of the vibrating motor or increasing the acceleration ratio of the transmission system, the vibration frequency of the linear vibrating screen can be increased.

Specific operation steps: Open the end cover at one end of the vibrating motor on the vibrating screen. There is a cam inside and a scale on the top. The frequency can be achieved by adjusting the number of cams.

There are many different classification methods for vibrating screens. For example, according to the movement trajectory, there are linear screens, circular screens and high frequency screens. So no matter what kind of vibrating screen, you have to buy it back. If we encounter the problem of slow discharge, how can we solve it?

The vibrating screen is a machine that uses a vibration exciter or a vibrating motor to drive the screen surface to perform high-frequency vibration, so as to screen materials and have the characteristics of high precision and high efficiency.

The vibrating screen discharges slowly or does not discharge, I believe most users have encountered it, so many users first feel that this is a problem with the machine, it must be designed by the manufacturer without designing, and in fact, this phenomenon is very common, and There are very easy to solve problems, because the root cause of these problems is the vibration source of the vibrating screen.

It is not difficult to find the root cause, and then solve the problem of slower discharge of the vibrating screen, that is, adjust the weight of the upper and lower ends of the vibrating motor. You can start from two aspects:

1. Increase the weight of two weights: increasing the weight of the eccentric mass can increase the excitation force of the entire machine. Users can increase the weight according to the number of layers of the vibrating screen and the specific gravity of the material, so the vibrating screen and the material can achieve the desired ideal effect.

2. Change the angle between the upper and lower weights: the angle of the weight changes, the movement trajectory and residence time of the material on the screen will change. The larger the angle, the smaller the eccentric force generated, and the longer the material is on the screen. The finer the screen, the slower the discharge speed. Conversely, the smaller the angle, the greater the eccentricity, and the shorter the residence time of the material. Accordingly, the discharge speed will increase. This type of adjustment is more suitable for coarse drying and screening of larger particles. Therefore, the user should adjust the angle between the two weights according to the nature of the material to be screened, so that the distribution of the material, the processing capacity and the super-netting speed can reach the ideal screening state.

When producing and designing the same type of vibrating screen, the setting is determined. Different materials require different adjustment methods. Users can adjust the angle of the hammer according to their needs. The vibrating screen is in ideal working condition.

Since the operation of the vibrating screen is closely related to the vibration exciter, we have to talk about the relevant content of the vibrating screen exciter.

Working principle of vibrating screen exciter

The vibrator is composed of two single unbalanced weight vibrators, and a pair of inertia gears mounted on the ends of the two vibrating shafts make them forced to contact (it can also be driven by dual motors). When the driving shaft rotates, the driven shaft rotates synchronously in different directions. In each instantaneous position, the component forces of the centrifugal inertial force generated by them always cancel each other out, and the component forces in the direction always overlap each other, thus forming A single exciting force along the direction drives the movement of the screen surface.

The function of vibrating screen exciter

The exciting force passes through the center of mass of the screen body;
The stiffness of the damping springs at the four-corner supports are exactly the same, and the distance to the center of mass should be similar. These two conditions are completely determined by the design and manufacturing accuracy. Under normal circumstances, the vibrating screen is forced to vibrate under forced alternating deformation, and the vibration intensity is large, and the signal that contains the dynamic characteristics is substantially annihilated. Therefore, it is difficult to realize the vibration screen in the case of braking failure based on the above-mentioned traditional model A complete reflection of dynamic characteristics. This model actually simplifies the vibrating screen body into a four-corner elastic support rigid body structure.

vibrating screen exciter Technical characteristics

The self-synchronization principle is used to make the vibrating machine produce linear vibration.
When working, fix the exciter on the excited part, and the excited part will obtain the required vibration.
Lubrication methods: grease lubrication and thin oil lubrication, customized according to customer requirements.
The motor is installed on the fixed base on the side (left or right) of the vibrating machine. The motor does not participate in vibration, and the motor is connected to the vibrator with a universal joint shaft.
The eccentric block is easy to adjust and disassemble.
The design life of the bearing is more than 10,000 hours.
Both contact and axial labyrinth seals are used for good sealing performance.
An oil injection hole is set above the casing to ensure good lubrication of the bearing.
It has the advantages of light weight, small size, simple structure, convenient installation and maintenance, and long service life.
It has the characteristics of stable and reliable operation, flexible adjustment and small maintenance.
The service life is 1-3 years.

Analysis on the screening movement track of various vibrating screens

2021-01-26/in News /by admin

Vibrating screening equipment generally uses a vibrating motor as an excitation source, so that the screen can achieve effective power. The different installation and combination forms of the vibrating motor on the vibrating body can produce different sportswear trajectories for the material by the vibrating screen, thereby achieving effective The purpose of screening and grading is to complete their own operations. The trajectory of the vibrating screen can be roughly divided into the following types:

1. Linear vibration

Linear vibration: the projection of the vibration trajectory of the vibrating body (vibrating box and material) on the horizontal and vertical planes is linear, and its vibration form is called linear vibration. This type of vibrating screen is called linear vibrating screen or linear screen. Install two vibration motors of the same model on the body of the vibration equipment so that the shafts of the two vibration motors are parallel to each other. When the two vibration motors rotate in opposite directions, the two vibration motors must run synchronously, and the body produces linear vibration.

2. Rotational vibration

Rotary vibration is also called three-dimensional vibration: the projection of the vibration track of the vibrating body on the horizontal plane is a circle or ellipse, and its vibration form is called rotational vibration. This type of vibrating screen is called rotary vibrating screen. Rotary vibration can be divided into three forms: flat-rotation type vibration, vortex type vibration and double-rotation type vibration. When the projection of the vibration trajectory of the vibrating body on the vertical plane is a horizontal straight line, the vibration form is called pan-rotation vibration; when the projection of the trajectory of the vibrating body on the vertical plane is a diagonal line, the vibration form is called Vortex type vibration; when the vibration track of the vibrating body is projected as a circle or ellipse on the vertical plane, its vibration form is called compound-rotation type vibration. Rotary vibration is usually generated by the vibration equipment excited by the vertical vibration motor, and the vibration form depends on the angle between the vibration blocks at both ends of the vertical vibration motor. It is also possible to install two foot-mounted vibration motors on both sides of the vibration device, so that the rotating shaft is at a set angle, and the vibration device will also produce rotational vibration.

3. Compound vibration

The vibration of the vibrating body is produced by two sets of excitation systems, and its vibration form is called compound vibration. There are generally two types of dual-frequency compound type and double-amplitude compound type. Some special performance vibrating screening equipment uses two vibration motors of different models and different speeds, which are installed at the receiving end and the discharge end of the screening equipment, so that the receiving end exhibits large amplitude and low frequency vibration, and the output The material end presents a small amplitude and high frequency vibration, and the middle of the screening equipment overlaps two kinds of vibrations, so that the screening equipment plays a more effective screening role.

4. Circular or elliptical vibration

The projection of the vibration trajectory of the vibrating body on the horizontal plane is a straight line, and the projection on the vertical plane is a circle or an ellipse, and its vibration form is called a circle or ellipse vibration. This kind of vibrating screen is called circular vibrating screen or circular vibrating screen. Usually a vibrating motor is installed on the body of the vibrating machine to produce this kind of movement. The circular or elliptical vibration occurs on a plane perpendicular to the rotation axis of the vibration motor, and its form depends on the relative position of the vibration motor and the center of gravity of the whole machine.

How to maintain linear vibrating screen in coal preparation plant

2021-01-26/in News /by admin

Linear vibrating screens are usually used for de-intermediation and dewatering operations in coal preparation plants. They are mainly used for de-intermediation and dewatering operations in coal preparation plants.

There are many types of structure and transmission methods for linear vibrating screens, such as flexible connection, universal joint shaft connection, etc. The excitation methods include eccentric sliders, box-type vibration exciters, etc. The vibrating screen manufacturer mainly introduces the following detailed introduction for the routine operation and maintenance of the linear vibrating screen in the form of the current compact box-type vibration exciter.

Main components of linear vibrating screen

1. Screen body: usually adopt ring-groove rivets to clean and seal assembly to avoid the corrosion of the bolt joint surface by wet objects. At the same time, the side panels are assembled without welding seams and rivets hydraulically to ensure that the overall structure has no residual stress.

2. Vibration beam: usually a box-shaped design, the main welds are fully penetrated, first-level UT inspection and magnetic particle inspection, and heat treatment to eliminate welding stress to ensure high strength. Before assembling, the mating surface of the excitation beam is precisely processed by CNC machine tools, which effectively guarantees the overall assembly quality of the screen.

3. Crossbeam: Usually circular special pipe design is adopted, and the main welds are all penetrated. First-level UT inspection and magnetic particle inspection are carried out, and heat treatment is carried out to eliminate welding stress and ensure strength. The surface can be treated with polyurethane spraying process to improve erosion and corrosion resistance.

4. Vibration exciter: It is composed of special vibration bearing, eccentric pendulum block, magnetic oil plug and other components, and uses splash lubrication to excite. The exciter can work normally under the temperature of -30℃~+80℃, usually with special respirator.

5. Intermediate shaft: Use an intermediate shaft to connect between the two exciters to ensure the synchronous rotation of the left and right exciters. Both ends of the intermediate shaft are connected with the pendulum block of the vibration exciter by a unique elastic rubber disc coupling. The intermediate shaft is a rigid shaft, maintenance-free and without lubrication.

6. Main drive shaft: The main drive shaft is a universal joint shaft that connects the statically fixed installation drive mechanism and the dynamic vibrating screen body.

7. Drive mechanism: The drive mechanism is composed of a motor, a belt drive and a countershaft assembly. The main motor has a large starting torque and fast acceleration, so that the screen machine quickly passes through the resonance zone. The motor is installed on the rail seat to facilitate belt tensioning. The transmission mechanism adopts belt drive to adjust speed and reduce speed, transmit power, and adjust the belt tension with guide rail seat screw tension motor. The countershaft assembly is composed of a countershaft, a bearing, an adapter sleeve, a labyrinth seal and an open bearing seat.

8. Cushioning spring: steel coil spring is used for vibration isolation and cushioning between the vibrating screen body and the installation base. The spring stiffness is small, which reduces the dynamic load on the base. Rubber pads are added at both ends of the spring to reduce the friction and friction noise between the spring and the steel spring seat plate.

9. Screen surface: According to the purpose and user needs, the screen surface adopts different types of sieve plates. The main types are: continuous sieve slotted polyurethane sieve plate, polyurethane frame stainless steel slotted sieve plate, polyurethane frame stainless steel woven sieve plate, polyurethane frame stainless steel punch Hole sieve plate.

The operating procedures of the linear dewatering screen

1. Before driving, check carefully whether the sieve plate is damaged, loose, whether the eccentric shaft bolt is loose, whether there is any debris on the screen surface, whether the chute is unblocked, the water spray device is intact, and no one is working on the equipment.

2. The screen surface should be flat, free from damage or looseness, and the joints should be tight. The sieve holes and sieve slits of the deintermediation sieve should not be too large, small, or excessively worn.

3. The exciter, vibration motor and other lubrication parts should be well lubricated; the support spring should be free from damage, lack and aging failure; all safety facilities should be complete and intact, and comply with relevant regulations.

4. Try to drive without load; the sieve that needs to be sprayed with water should not be blocked, otherwise it should be cleaned immediately.

Three, the start and stop sequence of the linear dewatering screen:

Start sequence:

1. The inspection before the start of the separation screen is completed, and the shift leader or production dispatcher has been given a driving instruction to confirm that the equipment in the next process has been started and operating normally before starting the screen.

2. After the sieve is started, first turn on the water spray and confirm that it is normal before allowing the material to be fed to the screen surface. Adjust the water spray size in time according to the material on the screen surface.

After the start-up is completed, perform a comprehensive inspection and make a record of the shift.

1. You must get a parking instruction before you can stop.

2. It must be known that the equipment in the previous process has indeed been stopped.

3. Before stopping, all materials on the screen must be unloaded, and then shut down after turning off the water spray.

Operation and maintenance

1. Check the incoming materials, discharge and spray pipes regularly during operation, and report them if they are blocked.

2. Frequently monitor the eccentric shaft, whether the sound is normal, whether the sieve plate is loose, whether there is water running on the sieve surface, report and deal with it in time.

3. During operation, pay attention to check the temperature of each bearing, the temperature of the motor, the sound, the working state of the coupling and the amplitude of the screen under different loads, and report the problem in time.

4. The screen box should vibrate smoothly during operation, and there should be no abnormal swings. If the screen box shakes, check the working conditions of the four support springs and the running direction of the motor.

5. Pay attention to the working conditions of the exciter and the vibration motor during operation. The spindle should rotate flexibly and the bearing should be well lubricated; pay close attention to the bearing temperature.

6. The vibrating screen should regularly check the concentration and particle size composition of the water under the screen to determine the wear of the screen. If the wear is serious, it should be replaced in time.

7. The de-intermediation vibrating screen should adjust the pressure and water volume of the water spray to ensure that the heavy medium of the product on the screen is flushed; often check (see, touch by hand) the de-intermediation effect and moisture of the product on the screen, and adjust according to the inspection result The amount of water sprayed can improve its cleaning effect; closely contact the density control driver to jointly adjust and ensure the deintermediation effect and dehydration effect of the deintermediation screen.

8. The technical indicators of de-intermediation and dewatering include: unit consumption of water spray, concentration of under-sieve and super-grain content, product on-screen and moisture. The driver should strive to complete the above-mentioned indicators stipulated by the factory.

The main measures to complete the index of removal of referral and dehydration

1. In order to strengthen the maintenance of the equipment, keep the vibrating screen in a good working condition; clean the nozzles frequently to ensure uniform spraying; strengthen the management of the screen surface and observe the dynamics during operation. After parking, check frequently, clean up frequently, fill loopholes frequently, and clear blockage frequently to ensure the effective separation (water) area of the screen surface.

2. It is strictly forbidden to put the scattered coal into the funnel under the sieve; it is strictly forbidden to run without water.

3. Regularly check, adjust and replace the coupling and support spring; clean the screen surface and chute; check the tightness of the screen surface, and deal with it if it is loose.

4. Use the parking time to perform equipment maintenance, and deal with problems that occur during operation and check after parking.

5. Do a good job in equipment and environmental sanitation, fill out the work log as required, and do a good job of shifting shifts.

What should I do if the linear vibrating screen fails?

2021-01-19/in News /by admin

In daily use, the linear vibrating screen will inevitably be damaged. As a professional vibrating screen manufacturer, Hiside gave us the following detailed introduction to the common faults and solutions of linear vibrating screens. Let’s take a look.

The linear vibrating screen is driven by double vibration exciters. When the two vibration exciters are synchronized and rotated in opposite directions, the excitation force generated by the eccentric block cancels each other in the direction parallel to the motor axis, and in the direction perpendicular to the motor axis. Stacking is a resultant force, so the trajectory of the screen is a straight line. The two motor shafts have an inclination angle relative to the screen surface. Under the combined force of the exciting force and the material’s self-gravity, the materials are thrown up and jump forward on the screen surface for linear motion, so as to achieve the purpose of screening and grading materials. Can be used to realize automated operations in the assembly line. It has the characteristics of low energy consumption, high efficiency, simple structure, easy maintenance, and fully enclosed structure without dust spillage. The high screening mesh is 400 meshes, which can screen out 7 kinds of materials with different particle sizes.

1. The pipe beam is broken

If the wall of the pipe beam is too thin, it may cause breakage. At this time, the thick-walled pipe of the same model or the larger one should be used. But it should not be too large or thick, because this will increase the vibration quality of the sieve and cause many problems; the joints of each sieve plate of the dewatering and de-intermediation screen must have horizontal and vertical beading. If there is no longitudinal beading, water The pipe beam will leak from the gap between the screens and the pipe beam will easily break at the scouring point; the wider the screen, the easier the pipe beam will break. According to experience, when the screen width exceeds 3m, use dual channels.

2. The beam is broken

The beam fracture is mostly due to the long working time at the critical frequency, the loosening of a large number of high-strength bolts that fasten the side plates, and the serious deformation of the spring makes the left and right heights vary greatly. It is also possible that the weight error of the eccentric block is too large, causing damage to the structural parts. The beam is broken. At this time, the damaged structural parts and beams should be replaced, the bolts should be tightened, and the quality of the eccentric block should be adjusted.

3. The screen frame is broken

The screen frame is prone to fracture due to shaking. The best way to solve this problem is to thicken the side plate or add additional plates to the local area of the side plate near the exciter to enhance the rigidity of the entire screen frame.

4. The discharge port is broken

Since vibrating screens are generally manufactured non-standard, the sizes required by customers are different. Some require the discharge port to be extended forward or downward. In this way, the discharge port will be relatively more likely to break. If it is the first design, the plate thickness or ribs can be strengthened. If it breaks accidentally, check the material quality. Also check whether the parameters of the vibrating screen are correct. Furthermore, during the feeding process, avoid excessive feeding of the vibrating screen at one time. The screen can be basically fully utilized. The excessive feeding amount not only affects the screening effect, but also the screened material cannot be discharged through the screen in time. Excessive weight backlog will also cause the break of the vibrating screen’s discharge port.

If the linear vibrating screen fails, you can refer to the above methods to solve it, but if your problem has not been solved, please contact the manufacturer for after-sales service, and ask professionals to repair it in time to avoid reducing your work efficiency.

How to improve the screening effect of mine vibrating screen?

2021-01-19/in News /by admin

In the concentrator, the vibrating screen is one of the commonly used grading equipment. The screening effect of the vibrating screen is of great significance to the follow-up operation. Therefore, how to improve the screening effect of the vibrating screen is a problem that needs to be considered. Analyze what factors affect the screening effect and how to improve the screening effect of the vibrating screen by changing these factors.

As a professional vibrating screen manufacturer, Hiside introduced many factors that affect the screening effect of mine vibrating screens. Three of the more important factors are the characteristics of the material entering the screen, the screen surface parameters of the vibrating screen, and the motion parameters of the vibrating screen. Below, our vibrating screen manufacturer will analyze these three factors one by one and discuss how to improve the effect of mine vibrating screens by changing these factors.

1. The characteristics of the material being screened

Different materials have different characteristics of their own, with differences in density, hardness, and water content. Generally speaking, the screening effect of materials with higher hardness and better brittleness is better than materials with lower hardness and poor brittleness. For the materials that enter the screen, there are two aspects that can directly affect the screening effect: the particle size of the material and the water content of the material.

When the particle size of the material is close to the mesh size, the screening efficiency will be significantly reduced. These particles may block the mesh and reduce the screening area. This is a common phenomenon in the closed-circuit crushing process. This situation can be improved by increasing the vibrating screen. The amplitude can be improved. The increase of the amplitude can promote the fine-grained material to pass through the screen surface and reduce the occurrence of clogging. In addition, it can increase the pass rate of the middle part of the screen to improve the screening effect. It can also be improved by changing the feeding method The utilization rate of the screen surface of the vibrating screen can be multi-channel feeding, which reduces the time and distance of the material on the screen moving on the screen surface and improves the screening effect.

When the material has a large water content, the material is prone to adhesion, which reduces the screening efficiency. Generally speaking, the wet material with a large water content can be improved by increasing the screen hole. However, if the material contains mud ,when the amount is greater than 8%, wet screening or pre-washing methods should be used for treatment.

2. Vibrating screen surface parameters

The screen surface parameters of the vibrating screen include the shape of the vibrating screen mesh, the opening rate of the vibrating screen surface, the material of the screen surface and so on. Generally speaking, a long screen surface has a long material residence time, more chances to penetrate the screen, and high efficiency, while a wide screen surface has better processing capacity. Practice has proved that the appropriate ratio of screen surface aspect ratio is 2:1~3:1.

The opening rate of the screen surface of the vibrating screen here refers to the screening area of the vibrating screen, which is the ratio of the screen area to the total area of the screen surface. The larger the screen area, the higher the productivity per screen surface and the higher the screening efficiency. As for the shape of the sieve holes, the choice is made according to the particle shape of the material. Generally, it is better to use square sieve holes for sieving round particles.

In terms of materials, different screen surface materials will also have an impact on the screening effect, which can directly affect the adhesion coefficient of minerals and screens. For viscous minerals, rubber and polyurethane should be used for screen materials with greater elasticity. Ensure that the material on the screen is loose. However, this type of material usually has the disadvantage of a small open porosity.

After combining the above aspects, we can know that when selecting the vibrating screen surface, different materials and opening rates should be considered comprehensively.

3. Motion parameters of vibrating screen

The motion parameters of the vibrating screen include two factors: the vibration frequency of the vibrating screen and the direction angle of the vibrating screen. Vibration enables the material on the screen surface to be thrown away from the screen surface, so that the coarse material reaches the upper layer of the material layer, and the fine material reaches the lower layer of the material layer, close to the screen surface, the screen layer is evenly distributed, and the passing rate of fine materials increases accordingly. For materials with large particle size, generally the higher the frequency, the higher the number of bounces on the screen surface, the increased chance of contact between the material and the screen surface, and the reduction of the occurrence of clogging of the screen holes. Therefore, an appropriate increase in the vibration frequency can effectively improve the screening effect.

The vibration direction angle is the angle between the vibration direction line and the screen surface. The larger the value of this angle, the smaller the horizontal movement distance of the material during the screening process, and the lower the movement speed on the screen. It is obtained through practice. For materials that are easy to screen, the direction angle should be small, and for materials that are difficult to screen, the direction angle should be large. In general, the direction angle of the linear vibrating screen is between 30 degrees and 60 degrees, and the direction angle of the circular vibrating screen is 90 degrees.

After the above analysis, we understand some of the factors that affect the screening effect of the mine vibrating screen and how to improve the efficiency of the vibrating screen. In short, we must choose the vibrating screen according to the actual needs, and choose the appropriate screen surface material as much as possible to improve the motor adjustment excitation. Vibration force, and try to ensure the lower water content of the material, and improve the screening effect under the premise of ensuring the processing capacity.