The belt conveyor has the remarkable characteristics of strong conveying capacity, long conveying distance, simple structure, easy maintenance, easy program control and automatic operation, and is widely used in mine production. The conveyor belt is not only the traction mechanism of the belt conveyor but also the load-bearing structure. It runs through the whole length of the conveyor, with large consumption and high cost. Once the belt tear occurs, one hundred thousand or even one million yuan worth of belt in just a few minutes will all be destroyed, resulting in huge direct and indirect economic losses. Therefore, it is very important to understand the causes of belt tearing of belt conveyors and to prevent it.
Causes of belt tearing of belt conveyor
The belt tear is a kind of damage form, which has the contingency, because the sharp sundries in the material in the belt conveyor in the normal transportation in the material gets stuck in the cutting hole or the idler gap causes the belt to tear most commonly.
The main reasons of the belt tearing are as follows:
Foreign body lacerations
Foreign body laceration is the main cause of belt laceration, which can be divided into three cases. One is that sharp foreign body directly pierces the belt and gets stuck between the sealing box and the supporting roller. The other is that foreign body gets stuck in the lower part of the feeding machine, the belt can not be reached when the material is loaded, but the belt gravity center moves up and scratches the belt when the belt is unloaded.
Thirdly, foreign objects are stuck in the gap between the rollers, it does not touch the belt when it is empty, and the belt’s centre of gravity shifts down when it is normally loaded, thus scratching the belt.
Belt misalignment
In the case of severe belt runout, folding may occur on one side, the belt may be scratched by the roller supports or other objects, or the belt may even be torn. Tearing caused by belt runout usually only tears the edge of the belt and does not occur on the inside of the belt.
Material compression
Large pieces of material in the feed hole stuck, a large amount of material backlog, resulting in abnormal operation, large pieces of material scratch belt, if not removed in time will cause belt tear. For the steel industry, large pieces of material have been removed before feeding, this rarely happens.
Core pulling and tearing(this type of tearing only occurs in steel-cord belts)
Due to long-term use of the steel rope core belt, the steel rope core will show different degrees of wear and tear, and in severe cases, the steel rope will leak or even break, when the broken wire rope reaches a certain length, it may wrap around any part of the belt conveyor and cause the belt to tear.
Improper installation of ancillary equipment
In addition to the threat of the material itself, the removal of the material from the conveyor belt itself during transportation is also a major cause of tearing. For example, vibrator liners and crusher hammer heads falling off can cause belt tears.
Plugging causes tearing
Transfer chute small, easy to obstruct the passage of materials and impurities caused by conveyor belt tear.
Tear caused by falling of intermediate idler
The conveyor belt is pressed directly against the supports that support the intermediate rollers. Heavy loads cause the belt to press against the support, which cuts through the belt like a knife, causing tears.
If the belt can not be replaced immediately after tearing, it can be used temporarily for a short time after drilling with electric drill on both sides of the tear and fixing with wire binding. Small tear length can be repaired, long-distance tear suggested to replace the belt. The repaired belt affects the use effect of scraper and cleaner, and it is easy to cause dust, and in the use process need to strengthen the regular inspection.
Prevention of Belt tearing
Proactive prevention of tearing from source
Strengthen the material quality control, increase the impurity removal equipment for impurity removal. In front of the primary belt set except big block device, reduce big block material into the entire conveying system.
Increase the capacity of the chute
On the premise that the width of the chute is determined by the belt width, the chute outlet is expanded upward to maximize the capacity of the chute so as to avoid blocking sundries or large pieces of material.
Strengthening the management of equipment
Improve the patrol and inspection of the belt conveyor, especially the management of other ancillary equipment, such as transfer funnel, sweeper and other facilities inspection, to prevent lining plate and other sharp objects fall off.
Improvement of conveyor structure
By reducing the fall difference at the drop point and increasing the buffer grille, fine material falls before large material, reducing impact, lowering the speed of material and reducing the possibility of impurities being inserted into the belt.
Improved belt structure
For example: improve the air tightness of the belt, to prevent the core layer of water, steel wire rust, require manufacturers to strengthen quality control, improve quality.
Add tear detection device
When a tear occurs in the belt, it is detected as soon as possible in the shortest possible time, an alarm is issued and the belt is stopped to minimise the length of the tear and reduce losses.
Use tear resistant belt
Tear-resistant belts use steel wire rope as the longitudinal skeleton material and add transverse reinforcement to the belt body as an anti-tear layer, but the cost of such tear-resistant belts is about 20% higher than that of ordinary belts.
Use of tear-detectable belts
A sensor with a closed coil is added to the belt, the detector is installed in the tear-prone part of the belt conveyor and the detector is connected to the controller. If the belt is torn, the closed coil of the sensor is cut off and when it passes the detector, the detector stops sending out pulse signals and the controller does not receive the pulse signal and immediately alarms and stops.
Although there are no obvious signs of belt tearing, we can reduce the probability of belt tearing to a minimum, or even eliminate it completely, by reducing the entry of large materials and sharp objects into the conveying system at source, improving the quality and responsibility of operators, strengthening equipment inspection and maintenance, correcting the deviation phenomenon and eliminating the hidden danger of belt tearing in a timely manner, and then using advanced anti-tear monitoring and control systems.