Research on noise reduction optimization design of belt conveyor

Noise pollution has become a major environmental problem perplexing people’s lives and employees of industrial and mining enterprises. The research on noise reduction has also become the main research topic of many researchers. For coal mining enterprises, the application of large mining equipment is inevitable, but it will also bring great noise pollution. How to reduce noise is an urgent problem to be solved. As an important transportation machinery in coal mining, belt conveyor has a serious noise problem, which directly affects the physical and mental health of enterprise employees. As the main transmission component of belt conveyor is reducer, which belongs to sealed gear transmission component, it will produce great noise under the working state of high torque; As the main carrier of coal, the belt will have vibration problems and noise pollution due to its long-distance transportation; Especially when the transportation line is too long, the belt conveyor needs to be built on the soil foundation, and the settlement of the soil foundation will lead to the imbalance of the frame of the belt conveyor, which will cause vibration and noise. In addition, the transportation process sometimes needs to pass through the village, and the noise directly affects the living environment of the villagers. Therefore, it is necessary to study all parts of the belt conveyor to reduce the pollution caused by noise.

1 Noise source analysis of 1 belt conveyor

The belt conveyor is mainly composed of three parts: driving part, middle section and end. Because the noise generated by each part is different, the noise of each part can be identified. It is easy to find that the main noise generating positions are reducer part, belt and feeding and unloading part.

The reducer of the belt conveyor is located between the connecting motor and the transmission drum, which is used to reduce the motor speed, increase the torque and provide driving force for the belt conveyor. Gear transmission is the main vibration source of noise excitation generated by the reducer. There will be friction, vibration, collision and other actions between gears during work, which will produce great noise pollution. The main noise can be divided into whistling noise and slapping noise.

As a traction mechanism and a bearing mechanism, the conveyor belt is generally made of rubber and has certain deflection and elasticity. It is easy to cause vibration and noise when carrying materials at a certain belt speed. The supporting mixer is used to support the conveyor belt to ensure the smooth operation of the conveyor belt. During the working process, the friction between the conveyor belt and the supporting rod, the conveyor belt cleaning brush and the conveyor belt will produce noise, and the noise will increase with the increase of belt speed. The key component of the belt conveyor is the belt. The work of the belt depends on the support and rotation of the supporting rod. The contact action between the belt and the supporting rod and the cleaning brush is carried out through friction, which is also one of the sources of noise, and the noise will increase with the increase of belt speed. In addition, the head and tail of the belt conveyor will be equipped with feed hopper and discharge chute. When the material collides with the hopper at high speed, it will also produce large noise.

2 noise reduction measures for belt conveyor

2.1 formulate noise reduction measures for reducer

The noise reduction measures of the reducer are mainly considered from the aspects of its internal structure, supporting rod shell material and shock absorption.

1) Reducing the vibration between the gears of the reducer can be considered from two aspects: changing the coincidence degree of the gears and increasing the addendum circle of the gears. Increasing the addendum circle and the coincidence degree between gears can reduce the transmission error, reduce the load and meshing in and meshing out impact of a single pair of teeth, and effectively reduce the dynamic excitation between gears. Changing the reducer gear into helical and bevel teeth can increase the contact area of the tooth surface and the length of the meshing contact line of the tooth surface, so as to ensure the continuous contact of the gears and reduce the impact vibration between the gears.

2) The reducer shell is made of gray cast iron, which can well absorb the energy released by vibration and have the effect of damping and vibration absorption.

3) Elastic connection between the chassis or vibration reducing pad and the ground to reduce vibration or reduce noise. Flexible connection can be adopted for fixing the reducer base to the ground, which can isolate a considerable part of vibration compared with rigid connection.

2.2 Replace the supporting concrete material

The supporting rod of belt conveyor is generally steel supporting rod, which will produce great noise during operation. In contrast, polymer rubber and nylon supporting rod can not only meet the requirements of belt conveyor for supporting concrete strength, but also have great elastic modulus, which can well reduce the noise between leather belt and supporting rod, but also reduce the friction coefficient between metal connecting buckle between belt and supporting rod, so as to reduce the noise. When processing the outer circle of the supporting wheel, the circumference of the supporting mixing cylinder shall be fully guaranteed to reduce the radial runout of the supporting mixing in the process of rotation.

2.3 Change the contact form between material and hopper

Both ends of the belt conveyor are fed at one end and discharged at the other end. There are hoppers at the inlet and outlet. By fixing the wear-resistant rubber surface on the side of the material impacting the hopper, the contact form between the material and the hopper is changed, and the rigid contact is changed into flexible contact, so as to reduce the vibration of the inner side of the metal and reduce the impact noise.

3. Application effect of noise reduction measures

Wangping coal power company has adopted the above noise reduction measures to transform the belt conveyor, and the noise reduction effect is remarkable. Through the measurement and comparison of the noise of the reducer, it is found that the noise value after the improvement is about 15 dB (a) lower than that before the improvement, indicating that changing the rigid connection to the flexible connection has a certain effect on the vibration reduction and isolation of the reducer. The noise value is measured at the inlet and outlet hopper. It is found that the noise value of the additional rubber surface is 17dB (a) lower than that of the non additional one.

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