In the mine production, belt conveyor is an important transportation equipment, especially the main transport belt is mine transport strength of the aorta. However, due to the
long conveyor belt, high-load operation, corrosion of steel cord, rope fatigue due to long-term repeated bending or because of broken wire rope core conveyor belt vulcanized
joints twitching and other reasons, may cause sudden rupture belt, belt laterally accidents. And thrust belt tension took place is a place, which is in the vicinity and there is
a large drive rollers variable slope at the carrier tape. Because strong inclination belt big long distance, large load in the event of belt slipped, it will destroy the rack, heat exchange manufacturers
damage to equipment, transportation roadway congestion, resulting in prolonged shutdowns and significant economic losses, and even casualties, extreme consequences severe.
Therefore Coal Mine Safety Regulations (2005) Section 375 provides: steel cord conveyor belt protection devices shall be provided. While Article 373 provides: used conveyor
inclined roadway, running on, you must also install fortification reversing units and brake units; belt should be added soft-start device. For the safety of coal production,
should take certain protective measures to actively prevent and avoid accidents belt, to avoid triggering a vicious accident.
A belt conveyor belt conveyor belt type of incident analysis of the lateral thrust belt when the accident occurred, the following are some of belt incidents and statistics: (a)
May 20, 1994, Shandong Province seventy-five coal mining 330 area in the normal production of steel cord conveyor operation, vulcanized joints running into the following
conveyor head off occurred at approximately 200 m broken down conveyor distance of 550 m, conveyor roller frame impact damage of more than 150 aircraft, roller damaged more than Telescoping conveyors
60 only, hit destroy Overhead Equipment hanging seat more than 20 aircraft.
(2) Since 1996, successively installed and put into use five steel cord conveyor. As the conveyor belt service life increases, there have been varying degrees of aging,
resulting in conveyor belt conveyor belt cover layer and adhesion strength between the core decreases. By the end of 2002 happened to five pull off the conveyor belt joints
accident, which directly affect the safety of the whole mine production.
(3) According to incomplete statistics, as of August 1995, there were Pingdingshan Mining Steel cord conveyor belt accident 16 cases, 15 of which occurred in the joints belt,
belt accounted for the total number of 93.75%.
2 Conveyor belt prevention and protection 2.1 Conveyor belt from prevention methods listed above conveyor belt accident shows, steel cord conveyor belt breaking strength
occurred in the vulcanized joints. As joint vulcanization process is not high or rubber aging joints, making it strong enough, the joints of steel cord conveyor belt breakage
caused by extraction. Or due to the long-term operation of the conveyor belt, causing wear of the rubber surface and the internal corrosion of the steel cord, or even broken
wire, thus making the belt strength decreases, resulting belt. In order to avoid breaking with accidents, measures can be taken: (a) in use should improve vulcanized joints
vulcanization process to ensure the quality of vulcanized joints.
(2) for steel cord conveyor belt joints and conducting periodic tests or real-time monitoring. Commonly used detection method is to use X-ray machines for steel cord conveyor
belt joints and steel cord for fluoroscopy and found serious or steel cord connector tic appears damaged timely manner.
You can also use the powerful real-time monitoring of steel cord conveyor apparatus for real-time monitoring of the joints of steel cord conveyor belt steel cord tic conditions
and the state, when the joints of steel cord twitching beyond the set range, or broken belt detection occurs when the alarm stop.
(3) steel cord conveyor belt joints occur the root cause of a large force caused by the wire rope, wire rope force if we can reduce the probability of occurrence of broken belt
will be greatly reduced. Because most of the drive on the belt conveyor is used in the upper double-drum drive, power in accordance with a? 2 distribution, as shown, the
advantage of this solution is simply furnished, the disadvantage is the belt tension, requires the use of high-strength belt, drives great need for excavation chamber.
Reduce rope force approach is to use multi-point-driven approach, the way multi-point driving drum style and linear friction unloading etc.
Drum Unloading belt can not prevent accidents, the use of small, multi-point linear friction drive used more often. Its working principle is the pressure in the driver master
belt conveyor, conveyor belt and the host by the drive belt between the friction drive device of the intermediate power transmission belt to the host, thereby reducing the
tension of the belt of the host. Drive more points, the host belt tension is smaller.
Intermediate drive means affect the friction traction output of the main factors: the host and the drive belt contact pressure between the conveyor belt; linear friction drive
of the length; master conveyor belt and the drive belt between the coefficient of friction.
22 multi-point drive technology advantages (1) reduce the belt tension. Each point belt tension after a drive on the decline again, driven more points, the maximum belt tension
is reduced the more. May opt for a lower intensity level conveyor belt which can ensure the safe operation and reduce overall cost. Or lower intensity level while increasing
belt safety factor, reducing the chances of belt. If the handpiece to drive three drive belt tension is reduced by about 60% can be selected by 40% of the belt strength (lower
cost) and the safety factor is increased by 50% at the same time.
(2) multi-point linear friction roller drive output shaft mounted backstop can effectively prevent the expansion of the accident off the belt, each drive unit itself is also a
belt protection device that can generate torque backstop to prevent the conveyor belt decline, and because belt tension is reduced, so that the moment of resistance against the
backstop requirements reduced.
(3) the total power of the conveyor remains unchanged, the use of multi-point drive means can reduce the driving power unit, so that the conveyor element part design compact,
universal, both to improve the parts of the processing conditions, and convenient to transport, installation and maintenance management.
(4) an intermediate multi-point driving device of simple structure, easy assembly and disassembly, according conveyors distance changes, additions or tear down the middle drive
unit, so that the conveyor can adapt to changes in transport distance, but also work in a reasonable power value, the full capabilities of the device, reduce energy consumption
and equipment waste.
Multi-belt drive technology prevent disadvantages: (1) multi-drive unit, the system links and more.
(2) because the motor characteristic curve hard, the motor has a manufacturing error, it will cause uneven distribution of electrical power is necessary to solve the power
allocation of each drive unit and sequential start-up problems. Can generally be solved using fluid coupling power allocation problem, can also be used for high CST.
(3) multi-point belt drive can greatly reduce the risk, but can not completely avoid the broken belt accident (such as spalling caused by pressure with a broken belt accident),
and the distance between the driving point is generally about 300 m, even after the occurrence of broken belt may cause a range of damage, in order to further reduce the loss of
belt can be installed between the drive belt other protective devices, such as the China University of Mining developed SPDB-I-type belt conveyor running on machine belt
protection device.
From the above analysis we can see a multi-point drive can greatly reduce the cost with a lower incidence of accidents off the belt, especially for long-distance running on the
new belt on.
3 Conclusion
Horizontal conveyor belt according to the accident investigation and statistics, we can see horizontal conveyor belt accident, especially on horizontal belt conveyor belt
accident hazards great cause of the accident is mostly because of the rope corrosion, fatigue, twitching rope core strength reduction caused by the accident took place is near
the upper part of the conveyor head position. Features multi-point drive belt just reduce the chance of an accident, if coupled with fewer belt installed protection device to
prevent the conveyor belt can be caused by a significant decline in fatal accidents.
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