Cause analysis and countermeasures

Abstract: The common fault forms of mining scraper conveyors are various mechanical and electrical faults such as failures of the reducer during use and maintenance, chain breakage, chain drop, motor heating, etc. Common safety accidents have head tilting and tail tilting. , Various types of accidents such as oil injection and fire of hydraulic coupling, injury caused by falling on the conveyor. It is an important part of the current electromechanical management to strengthen the maintenance of the scraper conveyor and adhere to preventive maintenance so that it will not fail or less malfunction. Important precautions to prevent safety accidents are to make inspection preparations before starting the machine. It is strictly forbidden for staff to ride on or work on the slides, and to check for power outages when they find faults.

Keywords: scraper conveyor; failure; safety accident; preventive measures

Scraper conveyor is currently the only coal transportation equipment with gentle inclined long wall coal mining face at home and abroad. The reason why the scraper conveyor can be widely used in the coal mining face is that it has the following advantages compared with other conveyors: the transport capacity is not affected by the blockiness and humidity of the cargo; the small height of the fuselage is convenient Loading; convenient for elongation or shortening of the fuselage; easy displacement; solid body, which can be used for blasting coal working faces, and can also be combined with coal miners and self-propelled hydraulic supports to form fully mechanized mining faces. Therefore, the scraper conveyor is an integral part of the coal mining equipment. Whether it can operate normally will directly affect the normal production of the working face.

I. Common failures and cause analysis

1. Motor failure and cause analysis

1) The motor does not start or stops slowly immediately after starting

Cause analysis: The load is too large; the operating components are severely blocked; the coal mining face is not straight and the convexity is serious; the power supply voltage is too low; the transformer capacity is insufficient and the starting voltage drop is too large; the switch works abnormally; the head and tail motors The time delay is too long, causing a single machine to drag; the motor itself is faulty.

2) Motor heat

Cause analysis: The motor fan suction port and heat sink are not clean, and the heat dissipation condition of the motor is not good; the overload operation time is too long; the bearing lacks oil or is damaged; Unstable; starting too frequently, starting current is large, fuse (chip) selection is too large, the motor works under starting current for a long time.

3) The motor sound is abnormal

Cause analysis: single-phase operation; bad connection head; too heavy load; bearing damage; gangs, roofing, etc., crushed the conveyor to death.

2. Failure and Cause Analysis of Hydraulic Coupling

1) Hydrodynamic coupling slips

Analysis of reasons: insufficient oil filling capacity of the fluid coupling; excessive coal accumulation in the chute; the scraper chain is stuck.

2) The fluid coupling is hot

Analysis of reasons: The ventilation holes of the coupling cover are not smooth; the oil charge is insufficient; the overload starts; the forward and reverse starts frequently.

3) Fusible protective plug of hydraulic coupling is melted and injected

Cause analysis: The conveyor is not running smoothly or the scraper chain is stuck; the conveyor is overloaded for a long time.

4) Oil leakage from fluid coupling

Cause analysis: The oil filling plug and thermal protection plug are loose; the seal ring and gasket are damaged.

3． Reducer failure and cause analysis

1) Gearbox housing is overheating

Analysis of reasons: too much or too little oil in the reducer; long-term use of lubricating oil; damaged bearings or shafts; the inside of the reducer is not clean.

2) The sound of the reducer is abnormal

Miscellaneous materials such as primary metal; bearing clearance is too large.

3) Reducer oil temperature is too high

Cause analysis: Lubricant is unqualified or is not clean; too much lubricant; poor cooling, poor heat dissipation.

4) Reducer oil leakage

Cause analysis: The seal ring is damaged; the closing surface of the reducer box is not strict, and the bearing cover bolts are not tightened tightly.

4． Failure and Cause Analysis of Scraper Chain

1) Scraper conveyor broken chain

Cause analysis: too much coal is loaded and the motor is started under overload; the chain is suddenly caused during operation: the gears are not well meshed; the bearings or gears are worn or damaged; the oil in the reducer is trapped; the chain is too tight; The chain is too loose or severely worn or the length of the two chains is different; the chain links of the two chains are not the same; the connecting bolts of the traction chain are missing; the deformed chain links are more; the working surface is not flat; Water rusts or cracks the chain.

2) scraper conveyor drop chain

Cause analysis: the machine head is not correct, the second section of the machine head or the base is uneven, the sprocket wear exceeds the limit, or bites into the debris, can make the scraper chain out of the gear teeth; the double-sided scraper chain of the two chains The tension is inconsistent, and the scraper is severely skewed; the scraper is too thin or excessively bent.

3) Scraper conveyor floating chain

Analysis of reasons: the conveyor is uneven, straight, and grooves appear; the scraper chain is too tight, squeezing coal to the side of the chute. The scraper chain runs on coal; the scraper is missing or bent too much; vermiculite is stuffed under the scraper chain.

4) Scraper conveyor bottom chain out of slot

Cause analysis: The scraper conveyor itself is not straight, the upper drum is concave, and it is excessively curved. The chute is severely worn; the length of the two chains is different, which causes the skew of the scraper or the shortening of the distance between the two chains due to the excessive bending of the scraper.

Analysis of common security accidents and causes

1. Head and tail turning accident

Small and medium chain conveyors such as SGW-40T, SGW-34T and SGD-20, when the tight chain, connecting chain, handling head drop chain, floating chain and other faults, the head or tail is often pulled up and warped. A person at the nose or tail hit the top plate and died.

1) Analysis of the causes of accidents caused by tipping of the nose

The head-turning injury accident occurred under the condition that the head and the transition groove are not connected with bolts or the head is not supported by the pressure column, and the scraper chain is in the following three situations at the same time: forward rotation to the head; The slot is blocked and the load suddenly increases; the slot is exited at the head part.

2) Causes of tail turning

The reason for the tail turning is that under the condition that the tail is not supported (column), the scraper chain is under the following three conditions at the same time: running or starting in the direction of the nose; the lower groove is stuck and the load Sudden increase; out of the slot at the tail.

2. Accidental injury caused by oil injection fire of hydraulic coupling

In recent years, the hydraulic couplings used in scraper conveyors and belt conveyors in China have experienced fuel injection and fire accidents many times, and some units have resulted in asphyxiation and death.

Cause analysis: The fuel injection fire of the hydraulic coupling must occur under the conditions that the transporter is overloaded, the hydraulic coupling does not use oil as the transmission medium, and the use of an unqualified fusible alloy protective plug is available. Or use of unqualified oil, overload of the transporter may also cause fuel injection and fire. The use of oil as the transmission medium of the hydraulic coupling is the design specification of the hydraulic coupling, while the use of unqualified fusible alloy protective plugs is a human accident (such as incorrect installation position, use of fuses) Instead of fusible alloys, plugging fusible plug holes with bolts or wooden plugs, etc.).

3． Chute convex injury accident

Cause analysis: The shearer's cutting floor is not flat on the fully-mechanized working face, especially after cutting out the steps, it will hinder the normal operation of the slippery work. If the slippery force is too large, the chute and the cable trough may be pushed up. If there is someone in the place where the cable trough is raised, there is a danger of injury.

4． Accident due to falling on scraper conveyor

Analysis of reasons: people walking in the chute that is stopped or in operation; when the scraper conveyor is opened, the driver does not send a warning signal to notify the relevant personnel to leave the transporter; the foot chain is used to temporarily handle the floating chain and fall .

Third, countermeasures to reduce failures and safety accidents

1. Countermeasures to reduce failures

1) The staff participating in the installation, operation, maintenance and troubleshooting should be familiar with the structure, operating principle and corresponding precautions of the scraper conveyor.

2) Before the conveyor is put into formal operation, the main parts of the nose, tail and fuselage must be carefully inspected. To ensure the laying quality and ensure that all components meet the requirements, the scraper chain must be tight and appropriate to avoid dropping, jamming, skipping and broken chains; ensure that there are no foreign objects in the chute that may hinder the operation, and all the barriers and guards are in place It is safe and reliable; and check all startup, control and communication equipment to ensure that its technical status is normal and good.

3) Maintenance personnel should do two tasks: regular inspections and regular maintenance. The purpose of maintenance is to timely deal with abnormal conditions that often occur in the operation of the equipment to ensure the normal operation of the equipment. It includes replacing some wearing parts, adjusting the tightening and lubricating, etc., so that the scraper conveyor can always keep running in good condition. It is actually an important measure to prevent equipment accidents, improve operating efficiency and extend the service life of equipment. Troubleshoot problems before they occur through regular inspections and periodic maintenance.

4) When the scraper conveyor fails during operation, it should be correctly judged and dealt with promptly to minimize the impact of the failure.

2. Countermeasures to reduce safety accidents

1) Caring for the physical and mental health of employees. People should be people-oriented in safety work, pay attention to distinguishing the abilities and intelligence of different people, pay attention to the mental and physical conditions of employees, recognize that the hidden dangers of "people" are the biggest hidden dangers, and that their work is strictly prohibited.

2) The driver must pass the technical training and hold a certificate to work.

3) Make inspection preparations before starting up. Check whether there are obstacles in the roadway; check if there are people on the transport plane; check if the cable is hung; check if the tail support of the machine is set up as required; warning signals or shouts must be issued before starting the machine. Can be booted.

4) It is strictly forbidden for the staff to ride on or work on the slides, and if the fault is found, they shall be cut off for maintenance to prevent people from being strangled or dragged by the conveyor.

5) The driver should stick to his post and report and deal with the accident in time to ensure the normal operation of the equipment.

4 Conclusion

By analyzing the common failures of the scraper during use and proposing preventive measures, it is helpful to solve the common problems in the use and maintenance of the scraper, play the effectiveness of the equipment, and increase the coal output. Practice has proved that the above method is simple and effective, and easy to popularize and apply.