LINEAR VIBRATING SCREEN

A linear vibrating screen is a type of screening equipment that utilizes linear motion to convey and separate different materials. It consists of a screen frame, a screen mesh, a vibration motor, and several supporting springs. The material to be screened is fed into the screen frame from the inlet, and as the screen vibrates, the material is separated into different sizes and discharged through the outlet.

The vibration motor generates a linear motion that causes the screen frame to vibrate. The vibration is transmitted to the screen mesh through the supporting springs, which causes the material to be sieved and sorted. The size of the mesh openings determines the size of the particles that pass through, while the amplitude and frequency of the vibration can be adjusted to achieve the desired screening effect.

Linear vibrating screens are commonly used in industries such as mining, coal, metallurgy, building materials, refractory materials, light industry, and chemical industry, to name a few. They are highly efficient and can handle large volumes of materials with ease. They can also be customized to suit specific needs and applications, such as multi-layer screens or screens with different mesh sizes.

Material Properties

(1) Material loose density

The bulk materials with larger loose density are easy to pass through the screen, and the screening efficiency is also higher; on the contrary, the materials with lower loose density and powdery materials are not easy to pass through the screen, and the screening efficiency is also low. The loose density of asphalt mixture is generally about 1.6tm 3.

(2) Material particle composition

In order to improve the screening efficiency. Under the condition that the gradation composition of the material being screened is determined. Determine the sieve size of the vibrating screen to minimize the proportion of difficult-to-screen materials (materials with a particle size of 0.7 to 1 times the sieve size) to the materials that should be screened.

(3) The relative size of the material particle size and the sieve hole

The particle size of the mineral material should be strictly controlled within the technical parameters of the equipment. If the particle size index difference is too large, it will cause a large production cycle and restrict the quality and processing capacity of the product. The penetration probability of materials in the screening process is affected by many factors, among which the most self-contained and important factor is the relative size of the particle size of the material and the size of the sieve hole.

Screen Surface Structure Parameters

(1) The length and width of the screen surface

Generally speaking, the width of the screen surface directly affects the productivity, and the length of the screen surface directly affects the screening efficiency. The screen surface is long, the material stays on the screen surface for a long time, and there are many opportunities to penetrate the screen, so the screening efficiency is high. In fact, the width of the screen surface has different effects on the screening efficiency and the length of the screen surface has different effects on the screening capacity. Generally, the ratio of width to length is 1:2~1:3.

(2) Screen shape and size

The choice of sieve hole shape mainly depends on the requirements of the particle size of the sieved product and the use of the lower product of the sieve. Compared with other shapes of sieve holes, the thickness of the under-sieve passing through the round sieve is smaller when the nominal size is the same.

Vibration Characteristics

(1) Screen surface inclination

The angle between the screen surface and the horizontal plane is called the screen surface inclination. The size of the inclination angle is closely related to the processing capacity of the screening equipment and the screening efficiency. When the inclination angle increases, the throwing strength of the material on the screen will be increased, so that the moving speed of the material on the screen surface will increase, which will increase the processing capacity of the screen machine, but the residence time of the material on the screen surface will be shortened, reducing the chance of particle penetration. , The screening efficiency is reduced. On the contrary, the throughput will be reduced and the screening efficiency will be improved.

(2) Vibration direction

The angle between the vibration direction line and the upper screen surface is called the vibration direction angle. The greater the value of the vibration direction angle, the shorter the distance the material moves during each throwing motion. The slower the forward movement speed of the material on the screen surface. The material can be fully screened, thereby obtaining a greater screening efficiency.

(3) Amplitude A and frequency w.

With the increase of the amplitude, the clogging of the sieve holes will be greatly reduced, and it is also conducive to the stratification of materials. The increase of the vibration frequency can increase the number of bounces of the material on the screen surface and increase the probability of the material through the screen, which is very helpful for accelerating the screening speed of the material and improving the screening efficiency. The choice of amplitude is based on the particle size and properties of the material to be screened.

For materials with larger particle size, choose larger amplitude and lower frequency; for materials with finer particle size, choose smaller amplitude and higher frequency.

Working Principle

Working principle of linear vibrating screen

advantages

The linear vibrating screen is driven by a double vibrating screen exciter. When the two vibrating exciters are synchronously and counter-rotated, the excitation force generated by the eccentric mass cancels each other in the direction parallel to the motor axis, and is perpendicular to the motor axis. The direction of the stack is a resultant force, so the trajectory of the screen machine 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.

Installation

Instructions for use of linear vibrating screen

Preparation before installation

Check whether the motor label conforms to the requirements.
Check whether the motor surface is damaged or deformed.
Check the fasteners of the motor to prevent loosening.
Check the power supply to see if it lacks phase, and run it for 5 minutes without load.
Check whether the rotation is flexible. If there is any abnormality, it should be eliminated.
Measure the insulation resistance with a 500 volt megohmmeter. The value should be dried on the stator winding, and the drying temperature should not exceed 120°C.

Installation and adjustment

The motor should be fastened to the mounting surface, which must be smooth and flat.
The motor can be installed horizontally.
Adjustment of exciting force.
The motor should have a reliable grounding. There is a grounding device in the motor, and the lead end has a mark. It can also be grounded by a solid bolt.
The motor lead adopts four-core rubber cable YZ-500V. When connecting to the power supply, the lead cable is not allowed to be snapped, and it is reliably fixed to the vibrating body

Debugging

Installation and commissioning and commissioning

(1) Installation:

⒈Before installing the machine, first check whether the parts are complete and damaged according to the packing list.

⒉Install the equipment according to the installation drawing. The foundation should have sufficient rigidity and strength to support all the dynamic and static loads of the vibrating screen.

⒊ Ensure that a minimum gap of 75mm should be maintained between the screen box and non-moving parts such as hoppers and chutes.

⒋When installing, the four corners of the screen box should be level.

(2) Adjustment and trial operation:

⒈The spring must be in a vertical state, and the contact surface between the upper spring support and the spring must be horizontal. After adjustment, the upper spring support is fixed on the trunnion of the screen box with bolts, and then welded into a whole.

⒉The no-load test run time is not less than 2 hours. After the no-load test run is qualified, it can be put into the load test run, and the load test run can be carried out according to the process test run requirements.

Use and Maintenance

Use and maintenance

The machine should be equipped with electrical protection devices.
In the initial stage of operation of the machine, check the anchor bolts at least once a day to prevent loosening.
When the motor rotation direction does not meet the requirements, adjust the power phase sequence.
When the machine is used again after being parked for a long time, the insulation resistance should be measured. It should be greater than 0.5 megohm for 500V megohmmeter measurement.
After the machine has been running for 1500 hours, the bearings should be checked and replaced immediately if there is serious damage.
The motor should be well lubricated. Replenish lithium base grease every two weeks or so. When refueling, add a proper amount of lithium base grease through the oil cup. When using sealed bearings, the motor is not equipped with an oil cup.

Daily maintenance

Before starting:

⑴, check whether the coarse and fine meshes are damaged

⑵, check whether the transportation support is removed

When starting:

⑴, pay attention to whether there is abnormal noise

⑵, whether the current is stable

⑶, whether the vibration is abnormal

After use: clean up after each use

Regular maintenance

Regularly check the coarse mesh, fine mesh and spring for fatigue and damage, and whether various parts of the fuselage are damaged due to vibration. The parts that need to be lubricated must be lubricated.