In recent years, with the increasing demand of belt conveyor, there is a lot of noise pollution, and most of these noises come from the spokes of belt conveyor. When the roller is running, the roller is noisy because of the uneven wall thickness and the errors in machining. When the bearing runs at high speed, the friction between the steel ball and the slideway will produce noise. This kind of roller is very noisy when transporting materials, which will affect the health of workers. At the same time, a large part of belt conveyors are laid near residential areas, and the noise during work will greatly affect the normal life of nearby residents.
1 Test background and conditions
1.1 Experimental Background
Production process of different low noise Joe wanted in material selection, production technology, have different structure forms, this experiment mainly study the effect of noise material for album, choice in different sections of the conveyor (a total of three segments), using different material along the noise test conveyor series, record numbers and verify low noise series of noise reduction effect.
The belt conveyor used in this test is required to carry out noise test along the belt conveyor because the conveying distance is too long and the laying route passes through residential areas. The prototype adopts steel wire rope conveyor belt, which contains part of uphill and downhill section, horizontal turning section and fully enclosed corridor. Roller sets are metal roller sets matched with the original machine and low noise metal roller sets, low noise nylon roller sets and low noise rubber roller sets provided by the enterprise.
The belt conveyor has a total length of about 12 km, conveying materials for cement clinker, working temperature of 45 ℃ ~80 ℃, belt speed of 3.70 m/s, conveying capacity of 3300 t/h.
The size of the upper spoke (bearing roller) is D194 mm×550mm; The size of the lower roller (return support) is B194mm ×800 mm; Roller tube body material is metal, metal coated nylon, metal coated rubber; The main test instruments and equipment are digital sound level meter, steel tape measure.
1.2 Test conditions
1)The corridor is 22 km long, conveying material is cement clinker, the temperature is 45℃~80℃, the normal working speed is 5 m/s, the throughput is 3 300 t/h, the use of wire rope conveyor belt, part of which is horizontal turning section, fully closed corridor.
2) Location of detection point : east longitude 119:45:0.99; For north latitude, 31:7:11.30; At 56.33 m above sea level.
3) The site situation of the detection point: the detection point is about 750 m away from the tail (as the transfer station). The corridor is flanked by factory areas and residential areas. The completely closed steel structure corridor is equipped with sound insulation boards on both sides. Due to the limitation of site conditions, the test work of various rollers and spoke could not be completed in the same section, so three different sections were selected to carry out the test. When tested, the running speed of the belt conveyor is 3.70m /s, and the throughput is 3 300 t/h.
The ultimate purpose of this experiment is to compare the noise reduction effects of different materials with low noise rolling. In order to ensure the correctness of the experimental results, the structure and size of the roller of different materials are exactly the same.
- Experimental Process
1) According to the requirements of reference [2], noise test was carried out in the middle of three different test sections. In the three test sections, the noise of the conveyor when the original machine is equipped with metal idlers is changed into low noise metal idlers, low noise nylon idlers and low noise rubber idlers respectively, and then the noise of the conveyor when the corresponding low noise idlers are adopted is tested.
2) Turn on the belt conveyor for preheating until the belt conveyor runs smoothly. Use a tachometer to measure the belt speed (adjusted to the linear speed gear) to ensure that noise measurement is carried out when the belt speed reaches 3.70m /s.
3) Use a digital sound level meter to measure the horizontal and vertical noise at each noise test point, once every 5s. The noise test point in the horizontal direction is 1 m away from the outer edge of the belt conveyor frame, and the noise test point in the vertical direction is 1 m away from the upper edge of the belt conveyor frame. Each test section measures the array data respectively and takes the average value as the conveyor noise measurement value of this test section.
In the experiment, the noise of 4 kinds of idler conveyors was tested respectively according to 4 quality indexes:
1) The noise value of the conveyor when the roller is equipped with the original machine is measured in the horizontal direction and vertical direction in the middle position of test section I, I and I ⅲ.
2) The noise of the conveyor when the low noise metal roller is used, and the noise value of the conveyor when the low noise metal roller is used is measured in the horizontal and vertical directions of the middle position of the test section ⅰ.
3) The noise of the conveyor when using low-noise nylon supporting system, and the noise value of the conveyor when using low-noise nylon rolling machine in the horizontal direction and vertical direction of the middle position of the test section ⅱ were measured respectively.
4) The noise of the conveyor when low noise rubber support is used is measured in the horizontal direction and vertical direction of the middle position of the test section ⅲ.
3 Experimental Data
This time in each test section of the noise test point were measured 6 groups of data, different test sections, using different roller conveyor noise test value.
As can be seen from Table 1, in the test section I, the drop value before using the metal roller and after replacing the low-noise metal roller reaches 7.6dB, a drop of 9.05%. In the test section ⅱ I, the drop value before rolling with metal support and after replacing low-noise nylon support reaches 9.3 dB, which is 11.41%. In the test section I ⅲ, the drop value before using the metal spoke and after replacing the low noise rubber roller reaches 12.7dB, a drop of 15.23%.
4 Comprehensive Analysis
According to the requirements of reference [2], the noise of conveyor with different idlers was tested in different test sections. Because the conveyor distance is long, and contains horizontal turning and downhill section, along the conveyor corridor support structure is composed of steel structure and concrete structure, coupled with the corridor support column spacing is different, so the conveyor noise along the various parts of the slightly different.
By comparing the test data of conveyor noise in the same test section with different material and structure forms, the following conclusions can be drawn for reference:
1) The noise value of the conveyor is reduced in different degrees when low noise metal roller, low noise nylon roller and low noise rubber roller are used;
2) In the test section with low noise metal support, low noise nylon roller and low noise rubber support, the noise value of conveyor with low noise rubber support decreases the most.