1 Introduction

At present, belt conveyors are widely used in various modern industrial enterprises such as power plants, metallurgy, chemicals, and building materials. Belt conveyors are widely used in horizontal or inclined transportation in underground tunnels, mine surface transportation systems, open-pit mines and concentrators. Some new users are not very familiar with the purchase, design, manufacture, installation and use of such equipment. After the installation and construction of the equipment is completed, it is usually necessary to start and debug the motor and the machinery it brings. The purpose of commissioning and operation is to test the quality of equipment design, manufacture, installation and commissioning, and to verify the reliability of continuous operation of the equipment. In actual work, unexpected abnormal phenomena are often encountered, causing the motor to fail to start and trip, belt deviation, abnormal noise, material scattering, slipping of the belt conveyor, broken shaft of the reducer, service life, and the curvature radius of the convex and concave sections. Faults such as the influence of the belt conveyor. This article is to briefly analyze these common faults and give some solutions.

2. Installation of belt conveyor

Before installing the equipment, it is necessary to understand it and master its structure so that the installation can be carried out smoothly. The structure of the belt conveyor is shown in the figure above, but its installation method will not be described too much in this article. The installation work is divided into the following three steps.

1. Basic re-measurement and release

Due to the large construction error of civil engineering, foundation re-measurement is essential in the installation process of the belt conveyor. First of all, the projected center line of the belt conveyor should be measured according to the reference line given by the construction drawings and civil engineering to see if it is offset. If there is any offset, it should be re-corrected so that the error is controlled within ±3mm; secondly, each branch should be determined according to the center line. Whether the position of the foundation is correct, and whether the area of ​​the supporting pad meets the requirements, and draw the center line of the foundation plate of the conveyor support on the supporting pad; finally, according to the 0m line given by the civil engineering, use a level to re-measure the foundation of each branch. elevation. If the elevation is low, the steel plate can be used to padded until the error with the design elevation is within ±5mm. The connection between the steel plate and the foundation plate shall be welded by the open V-shaped glass mouth full welding, and the welding foot shall reach the thickness of the steel plate; if the elevation is high, The foundation should be removed by the civil engineering unit and poured again.

2. Installation of head, tail and middle support frame

First use a crane to hoist the head and tail into place, align the equipment according to the already placed basic line, and use a line pendant and a level ruler to find the verticality and levelness of the equipment. Qualified welders weld the foundation plate and the embedded plate together to fix the equipment. Then, install the intermediate support frame. In order to save manpower, material and financial resources, the segmented hoisting method should be adopted as much as possible, and a large number of high-altitude operations should be moved to the ground to complete. How to ensure that the upper plane of each segmented support is in a line and avoid the stepped shape is a difficult point in on-site construction. The solution is to hang a heavy object at both ends of a 0.7mm steel wire, hang it at the center of the head roll and the tail roll, and then determine the height of the roll on the middle support frame according to the steel wire.

Third, the installation of the belt

During installation, it is often limited by the site, and it is difficult to use construction machinery. For conveyors designed with a fixed angle, the belt should be penetrated from the upper end, and the belt should be pulled in place with a special clamp and a chain hoist. When bonding, the belt at the interface should be cut by 1/2 of the thickness, and the adhesive should be applied. The two ends should be firmly stuck with special clamps to avoid the belt being loosened by force. The lap length should not be less than 1.0m. Pay attention to the ambient temperature when bonding, and take protective measures in time when the temperature is too low.

3. Debugging of belt conveyor and handling of common faults

1. Inspection and trial operation before commissioning

The debugging of the equipment is related to the future operation and can also detect whether there is a problem with its installation. Through simple debugging, the quality of the equipment can be checked, so this link also plays a very important role. The inspection and debugging methods of the belt conveyor are as follows:

(1) First, check whether the conveyor bracket is firmly installed, whether there are any missing welds, and check whether the rotation of the limit roller, tension roller and guide roller is flexible one by one, and whether the driving roller and driven roller are filled with oil.

(2) After the above confirmation is correct, start the driving roller motor by jogging. If the relay trips, it must not be started by force. Check whether the rainwater enters the driving roller motor and causes a short circuit. After the jog is correct, the driving roller motor can be started normally.

(3) During normal operation, adjusting the belt is a difficult point in this step. If the belt deviates, adjust the adjustable nut at the tail; if the adjustment is invalid, check whether the installation of the guide roller is correct. One end of the bracket is cut, displaced and welded. If the belt is too tight or too loose, the tension roller should be adjusted to make it tight.

During the debugging process, a trial operation team should be formed by professionals, and each professional is responsible for the division of labor, so as to deal with various abnormal phenomena that may occur at any time. After normal startup, if there is no abnormal phenomenon, it can run continuously for 8 hours and then stop, ready to participate in the joint trial operation of the whole system.

2. Failure analysis and handling during operation

Due to improper use during use, not strictly operating according to the operating procedures, and not carrying out timely cleaning and inspection after use, and not carrying out regular and reasonable maintenance, some common faults in use may occur: such as abnormal phenomena of the motor; belts deviation, material scattering, abnormal noise, belt slippage, shaft breakage of the reducer, service life, the influence of the curvature radius of convex and concave sections on the belt conveyor, etc. These fault phenomena will be described in detail below.

1. Motor failure

The simple way to judge the fault of the motor: First, you must have enough understanding of the motor and be familiar with its common faults, and then judge whether the motor is running normally by observing its operation status, touching the casing, smelling the smell, listening to the sound, etc.

1.1 The motor does not start or slows down immediately after starting

The reasons for this phenomenon are:

(1) Line failure;

(2) Protect the electronic control system from locking;

(3) Contactor failure;

(4) Voltage drop;

In this case, the line should be checked immediately, and the protections such as deviation, limit, and parking along the line should be checked. Check voltage, check overload relay.

1.2 Motor heating

Due to overloading, excessive length or the belt being blocked, the running resistance increases and the motor is overloaded; the poor lubrication conditions of the transmission system also lead to an increase in electrical power; secondly, coal dust accumulates in the motor fan air inlet or radial gasket, Deteriorating the heat dissipation conditions; in the case of dual motors, the shaft power distribution is uneven due to the different motor characteristic curves or the difference in the diameter of the drum. frequent operations, etc.

Solution: measure the power of the motor, find out the cause of overload operation and treat it symptomatically; add lubrication to each transmission part in time to remove coal dust; use equal-power motors to make the characteristic curves tend to be consistent, and adjust the oil charge of the coupling to make the two motors rationally distributed ; Reduce the number of operations.

2. Treatment of belt deviation of belt conveyor

Belt misalignment is the most common fault when the belt conveyor is running. In order to solve this kind of failure, it is necessary to pay attention to the dimensional accuracy of installation and daily maintenance. There are many phenomena and reasons for deviation, and different adjustment methods must be adopted according to different deviation phenomena and reasons to effectively solve the problem. This paper is to use the mechanical principle to analyze and explain the causes and treatment methods of such failures.

2.1 Adjusting the load bearing roller set

The verticality error between the installation position of the load-bearing idler set and the center line of the conveyor is large, which causes the belt to deviate in one direction in the load-bearing section. As shown in the figure below, when the belt runs forward, a forward traction force Fq is given to the idler. This traction force is decomposed into a component force Fz that makes the idler rotate and a lateral force Fc, which causes the idler to move axially. , Since the fixed idler of the idler bracket cannot move axially, it will inevitably generate a reaction force Fy on the belt, which will move the belt to the other side, resulting in deviation.

It is not difficult to understand the reason for the deviation of the belt after figuring out the force of the bearing roller set when the installation is skewed, and the adjustment method is also clear. The first method is to install on both sides of the idler set during manufacture. The holes are machined as long holes for easy adjustment. The specific adjustment method is shown in Figure 2. The specific method is which side of the belt is biased, which side of the idler group moves forward in the forward direction of the belt, or the other side moves backward. As shown in Figure 2, the belt is deviated in the upward direction, the lower position of the idler group should move to the left, and the upper position of the idler group should move to the right.

2.2 Install the self-aligning idler set

Install the self-aligning idler set. There are many types of self-aligning idler sets, such as intermediate shaft type, four-link type, vertical roller type, etc. The principle is to use blocking or the rotation of the idler in the horizontal plane to block or generate lateral thrust to make The belt is automatically centripetal to achieve the purpose of adjusting the deviation of the belt, and its force is the same as the deflection force of the bearing idler group. Generally, it is more reasonable to use this method when the total length of the belt conveyor is short or when the belt conveyor runs in both directions, because the shorter belt conveyor is easier to deviate and is not easy to adjust. The long belt conveyor is best not to use this method, because the use of the self-aligning idler group will have a certain impact on the service life of the belt.

2.3 Adjusting the position of the driving roller and the redirecting roller

The adjustment of the driving drum and the reversing drum is an important part of the belt deviation adjustment. Because a belt conveyor has at least 2 to 5 rollers, the installation position of all the rollers must be perpendicular to the center line of the belt conveyor in the length direction. As shown in the figure below, when the drum is deflected, the tightness of the belt on both sides of the drum is inconsistent, and the traction force Fq along the width direction is also inconsistent, increasing or decreasing. The moving force Fy causes the belt to deviate to the loose side, that is, the so-called "running loose but not running tight".

The adjustment method is: for the head roller such as the tape deviating to the right side of the roller, the bearing seat on the right should move forward, and the tape deviating to the left side of the roller, then the bearing seat on the left should move forward, Correspondingly, the left bearing seat or the right bearing seat can also be moved backward. The adjustment method of the tail roller is just the opposite of that of the head roller. After repeated adjustment until the belt is adjusted to the ideal position. It is best to install the exact location of the drive or redirection drum before adjusting it.

2.4 Adjustment of tension

The adjustment of the belt tension is a very important part of the deviation adjustment of the belt conveyor. The tensioning device of the conveyor makes the tension of the belt insufficient, and the belt does not deviate when there is no load or a small amount of load. When the load is slightly larger, the deviation will occur. The tensioning device is an effective device to ensure that the tape always maintains sufficient tension. If the tension is not enough, the stability of the tape will be poor, the greater the influence of external force interference, and the slipping phenomenon will occur in severe cases. For the belt conveyor using the heavy hammer tensioning device, it can be solved by adding counterweight, but it should not be added too much, so as not to cause the belt to bear unnecessary excessive tension and reduce the service life of the belt. For belt conveyors using screw tensioning or hydraulic tensioning, the tensioning stroke can be adjusted to increase the tensioning force. However, sometimes the tensioning stroke is not enough and the belt is permanently deformed. At this time, the belt can be cut off and re-glued.

2.5 Deviation caused by different belt diameters

Machining errors on the outer surface of the drum, coal sticking or uneven wear causes different diameters, and the belt will deviate to the side with the larger diameter. This is the so-called "run big and not run small". Its force situation is shown in Figure 4: the traction force Fq of the tape produces a moving component force Fy to the larger diameter side, and under the action of the component force Fy, the tape is offset.

In this case, the solution is to clean the surface of the drum to clean the sticky coal, and the processing error and uneven wear should be replaced and reprocessed.

2.6 The position of the blanking material at the transfer point is not correct, causing the tape to deviate

The blanking position of the material at the transfer point has a great influence on the deviation of the belt, especially when the projection of the two belt conveyors on the horizontal plane is vertical. Generally, the relative height of the upper and lower belt conveyors at the transfer point should be considered. The lower the relative height, the greater the horizontal velocity component of the material, the greater the lateral impact force Fc on the lower belt, and the material is also difficult to center. To deflect the material on the belt cross section, the horizontal component Fy of the impact force Fc eventually causes the belt to deflect. If the material is skewed to the right, the belt is skewed to the left and vice versa. For the deviation in this case, the relative height of the two belt conveyors should be increased as much as possible in the design process. The form and size of the upper and lower hoppers, guide troughs and other parts of the mobile bulk material conveying machinery limited by space should be carefully considered. Generally, the width of the guide groove should be about two-thirds of the belt width. In order to reduce or avoid the belt deviation, a baffle plate can be added to block the material and change the falling direction and position of the material. The material on the belt is not centered see Figure 5

2.7 Deviation caused by the belt itself

Problems with the belt itself, such as long-term use of the belt, aging deformation, edge wear, or the incorrect center of the re-made joint after the belt is damaged, these will make the tension on both sides of the belt inconsistent and lead to deviation. In this case, the whole length of the belt will deviate to one side, and the maximum deviation is at the incorrect joint. The only way to deal with it is to remake the rubber joint with the incorrect center, and replace the aging and deformed belt.

2.8 Adjustment of deviation of belt conveyor in two-way operation

The adjustment of the deviation of the belt of the two-way belt conveyor is relatively more difficult than the adjustment of the deviation of the one-way belt conveyor. In the specific adjustment, one direction should be adjusted first, and then the other direction should be adjusted. When adjusting, carefully observe the relationship between the belt movement direction and the deviation trend, and adjust one by one. The emphasis should be placed on the adjustment of the driving drum and the reversing drum, followed by the adjustment of the idler and the adjustment of the blanking point of the material. At the same time, it should be noted that when the belt is vulcanized at the joint, the force in the length direction of the belt section should be uniform, and the force on both sides should be as equal as possible when the guide chain is used for traction.

3. Scattering of belt conveyor

Scattering of belt conveyors is a common problem for many reasons. But the key is to strengthen the daily maintenance and maintenance.

3.1 Sprinkling at the transfer point

The material spread at the transfer point is mainly in the drop hopper, guide trough, etc. If the belt conveyor is seriously overloaded, the rubber apron of the material guide chute of the belt conveyor is damaged, and the steel plate at the material guide chute is designed to be far away from the belt. The above situation can be solved by controlling the transportation capacity and strengthening the maintenance.

3.2 Scattering when the concave belt is suspended

In the belt section of the concave section, when the curvature radius of the concave section is small, the belt will be suspended. At this time, the groove formation of the belt will change, because the belt has left the grooved idler group, and the groove angle will generally become smaller, so that part of the material will be scattered. Therefore, in the design stage, a larger radius of curvature of the concave section should be used as much as possible to avoid such a situation. For example, in the mobile mechanical ship loader and stacker-reclaimer equipment, in order to shorten the tail car, the concave section here is designed as a transition area without arc, and it is easier to spread the material when the belt width is selected with a small margin.

3.3 Sprinkling when deviating

When the belt is deviated, the material is scattered because the height of the two edges of the belt has changed when the belt is running, one side is high, and the other is low, and the material is scattered from the lower side. The treatment method is to adjust the deviation of the belt.

4. Abnormal noise

When the belt conveyor is running, its driving device, driving roller, reversing roller, and idler group will emit abnormal noise when it is not normal. According to the abnormal noise, the fault of the equipment can be judged.

4.1 The noise when the roller is seriously eccentric

When the belt conveyor is running, the idler often produces abnormal noise and periodic vibration. Especially the return idler, because of its large length, heavy self-weight, and relatively large noise. There are two main reasons why noise occurs