The belt conveyor is off-track and the idler is not running flexibly. Explain the cause of the failure and countermeasures in detail

Conveyor belt deviation phenomenon and solutions

The conveyor belt is an important and one of the most expensive parts among all the belt conveyors components,and its price accounts for about 25% to 50% of the total price of the conveyor.Conveyor belt is not only a traction member,which transmits power and movement, but also a load-bearing member,supporting material loads.When the working conditions are complicated, the deviation of the conveyor belt is often encountered.

The deviation of the conveyor belt may cause friction between the edge of the conveyor belt and the conveyor frame,resulting in premature damage to the edge of the conveyor belt, which may affect the service life of the conveyor and the conveying capacity of the material; in the worst case, it may cause material scattering or even shutdown accidents,directly affects production.

Reason

The main reasons for the deviation of the conveyor belt are as follows：      

(1) The reason of conveyor itself:

①The frame has poor rigidity and large deformation under load;

②The cylindricality error of the outer circle of the pulley is relatively large;

③The idlers are not rotating flexibly, causing uneven force on both sides of the conveyor belt;

④The parallelism error of the cylindrical axis between the pulley is relatively large;

⑤The quality of the conveyor belt itself has problems, uneven thickness, vibration during operation or inconsistent lengths of both sides of the belt, resulting in deviation of the conveyor belt;

⑥The joints of the conveyor belt are not parallel, and the connection error is large.       

(2) The reason of installation and adjustment aspects:

①The verticality error between the axis of the transmission and reversing idler and the center line of the conveyor is relatively large, which will cause a large inclination between the conveyor belt and the horizontal line during operation;

②The verticality error between the axis of the idler and the center line of the conveyor is relatively large;

③The connection strength between the frame and the ground is not enough, and the frame is unstable;

④The installation position of the guide baffle of the guide trough and the discharge trough is improper, and the uneven force on both sides of the conveyor belt will cause deviation during operation.    

(3) The reason of use and maintenance:

①The cleaning performance of the cleaner is not good, and the outer diameter of the pulley or the idler is partially increased during use; 

②The position of the feeding port is improper, causing the material to be eccentrically loaded on the conveyor belt;

③Improper maintenance and adjustment;

④For the steel cord conveyor belt, due to the uneven force of the steel cords in the manufacturing process, the conveyor belt will deviate during operation, or the strength of the conveyor belt will be poor, and the elongation will be large after being loaded, causing vibration and deviating;

⑤ The vibration of the conveyor system during operation will also cause the conveyor belt to deviate.

2.Improvement measures     

For the deviation of the conveyor belt caused by conveyor manufacturing, it is mainly to prevent and reduce the occurrence of the deviation of the conveyor belt by improving the accuracy of design and manufacturing.

The deviation caused by improper installation and adjustment and daily use should be considered from the following aspects.

1) The deviation of the conveyor belt on the driving pulley or the tail pulley is usually eliminated by adjusting the position of the pulley bearing seat. The specific situation is analyzed in detail, and the following methods are used to solve the problem in a targeted manner.      

a. The axis of rotation of the pulley itself is not perpendicular to the longitudinal centerline of the conveyor, causing the conveyor belt to be loose while tightening, and the belt will move to the loose edge from the tightening side, causing deviation. The position of the bearing seat of the tight side should be adjusted so that the lateral tension of the belt is equal to eliminate the deviation. If the tail pulley is a spiral tensioning pulley, the cause of the tail pulley deviation may also be caused by the unequal top tightening forces of the spiral rods on the two sides of the tensioning device, resulting in an imbalance.   

b. The axis of the pulley is not level, and the height difference of the bearings at both ends is another cause of head or tail pulley deviation. At this time, the axis of the pulley  can be leveled by adding or subtracting spacers on the bearing seats at both ends of the pulley to eliminate the deviation of the conveyor belt.    

c. Adhesion of materials on the surface of the pulley is equivalent to increasing the partial diameter of the pulley. The empty section of the conveyor belt should be cleaned to reduce the adhesion of materials or the accumulation of dust on the conveyor belt.  

2) In addition, the deviation of the conveyor belt between the head and the tail is called the middle or partial deviation. The reason for this kind of deviation is more complicated. It is related to the contact of the conveyor along the way. Specific problems need to be analyzed in detail, and the following methods are used to solve them in a targeted manner.  

a.The axis of the loaded or unloaded branch idler is not perpendicular to the running centerline of the conveyor belt, causing the conveyor belt to deviate at the idler. The deflection side idler should be adjusted to the running direction of the conveyor belt. At this time, it is often necessary to adjust several adjacent groups of idlers to achieve the purpose of eliminating deviation, and the angle of deviation of each group should not be too large.    

b.The deviation caused by the joint interface of the conveyor belt and the center line of the belt is not perpendicular should be eliminated by improving the connection accuracy of the belt during installation.  

c.The direction of loading materials on the conveyor belt is not correct, causing serious uneven distribution of the material's lumpiness and weight along the bandwidth direction, causing deviation, which should be eliminated by properly adjusting the position of the blanking tube and the material guide.    

d.application of air film to adjust the deviation of the conveyor belt. However, due to the high manufacturing cost, and there are still some technical problems that have not been solved well, it is difficult for this method to be popularized and applied for a while.     

The main reasons for the inflexible running of idlers and their solutions   

There are many idlers in the belt conveyor, which is one of the important components of the conveyor. Its price accounts for about 25% of the total price of the conveyor. The maintenance and replacement cost of the idler is also an important part of the operating cost of the belt conveyor. The operation of the idler has a great influence on the running resistance, power consumption, the service life of the idler and the conveyor belt, the maintenance workload and the transportation cost of the entire conveyor.

1.Reason

The main factors that affect the flexibility of the idler and its service life are as follows.      

(1) The manufacturing quality of idlers. It is mainly manifested in the insufficient rigidity of the bearing seat, which makes it difficult to ensure the assembly accuracy of the idler, which restricts the flexibility of the idler's operation.         

(2)Sealing, lubrication and maintenance. Due to the harsh working environment of belt conveyors, generally speaking, the dust on the site is very large. The sealing form of the bearing seat has a great influence on the running flexibility of the idler. If the sealing is not good, dirt will easily enter the bearing and cause inflexible idler rotation; in addition, if common calcium-based grease is used for bearing grease, it is easy to become discolored and dry, and cannot provide good lubrication.

2.Improvement measures  

(1) Ensure the specified accuracy requirements in the manufacturing process of the idler. For example, the accuracy of the inner hole of the stamped bearing housing must reach level 3, and the dimensional tolerance, coaxiality and ovality of the two ends of the tube must meet the national standard, and cannot exceed the tolerance.  There must be strict quality inspections on the products to ensure that all manufactured products are qualified.    

(2) In terms of sealing and lubrication, the equipment should be equipped with qualified lubricating materials, such as lithium-based grease, which can improve the lubrication of the bearing. This is very necessary to extend the service life of the idler.    

(3) The bearing seat is supported by a radial ball bearing and a plastic sealing ring labyrinth seal structure, which can ensure that the idler is reasonably stressed during operation, and has good dust-proof effect, low resistance, and convenient assembly and disassembly, easy maintenance, and Effectively reduce the operating cost of the conveyor.