Condition based maintenance is the development direction of coal mine equipment management

1 Introduction

To improve the reliability and utilization rate of coal mine equipment is one of the keys to improve coal mine production. Traditional methods of fault maintenance and regular maintenance can not meet the requirements of production development. Due to the formation of modern mine intensive production mode, large-scale and automation of equipment, condition based maintenance system based on equipment condition monitoring and fault diagnosis technology is an advanced and effective maintenance mode.

The so-called equipment condition maintenance mode is to conduct continuous or periodic tracking and monitoring of equipment operation status, timely diagnose and predict equipment failure, establish a complete equipment condition file, determine the equipment maintenance time and content, and prepare the unit parts or components that need to be replaced for maintenance, so as to shorten the downtime, reduce the maintenance cost and improve the utilization rate of equipment.

2. Disadvantages of regular maintenance

The limitations of traditional scheduled maintenance can be summarized as follows:

(1) Unnecessary maintenance may increase the failure rate

According to statistics, frequent regular overhaul will increase the failure rate. Realizing condition based maintenance can reduce the failure rate by 75%.

(2) It may increase the maintenance cost, cause the waste of working hours, regardless of whether the equipment is in good or bad condition, and maintain according to the plan mechanically, which will inevitably lead to excessive maintenance and waste.

(3) The operation rate and production efficiency of the equipment are reduced.

(4) It leads to the rigid thinking of maintenance personnel, and is not good at diagnosis and maintenance of "abnormal conditions" of various states.

3 application of equipment condition maintenance technology in mines at home and abroad

(1) Foreign application examples

Bougainville copper mine in Australia has been in stable production since it was put into operation in January 1972. It is one of the largest open-pit mining enterprises with the best economic benefits in the world. The mine has always attached great importance to the application of equipment condition monitoring and fault diagnosis technology, implemented the equipment condition maintenance system, and constantly improved the utilization rate of equipment.

The monitoring center of the mine is equipped with the most advanced monitoring and diagnostic equipment and a special sampling vehicle. More than 3000 lubricating oil and bearing vibration test sampling points have been set up for the more advanced large-scale equipment such as 13m shovel, 154T dump truck, + 250 rotary drilling machine, ball mill and crusher, with an average of about 110 oil samples and 935 test items tested every day. Input all the analysis results into the computer system before 4 o'clock in the afternoon every day. The equipment executive manager determines the maintenance time and content of the equipment through the results reported by the computer system. For large-scale fixed equipment, the monitoring center shall assign special personnel to the site to collect vibration measurement signals, conduct spectrum analysis and pattern processing indoors, and give an alarm in case of any abnormality.

(2) Benefits of equipment condition maintenance

The use of condition based maintenance in mine equipment management can bring many benefits: ① improve the equipment integrity rate. For example: the intact rate of the drilling rig is increased to 97.4%; the intact rate of the ball mill is increased to 99%; the intact rate of the crusher is increased to 98.1%; ② the hidden dangers are found in time through the condition monitoring, and measures are taken to avoid the occurrence of major accidents; ③ the service life of the equipment is extended, and the overhaul cycle can be appropriately extended; ④ oil is saved; ⑤ Shorten the maintenance downtime of the equipment and increase the effective operation time of the equipment.

(3) Application in coal mines in China

At present, equipment condition monitoring and fault diagnosis technology has been widely used in modern enterprises, such as petroleum, chemical, electric power, metallurgical industry equipment management. As the maintenance cost accounting of China's coal enterprises has not been put in an important position, condition based maintenance technology has not been widely used in the coal industry. Only a few enterprises in China have applied the technology of equipment condition monitoring and fault diagnosis in coal production, which has also achieved good results.

Sanhejian coal mine of Xuzhou Mining Group Co., Ltd. adopts state maintenance for only one year, which accurately forecasts several major faults and hidden dangers, ensures the safety of equipment and saves 1.72 million yuan of various costs. Good economic and social benefits have been achieved. For example, the problem of unbalance of centrifugal fan has been solved successfully. G4-73-11n028 D centrifugal fan is composed of synchronous motor, axle box and impeller. Equipped with motor TD 116 / 64-10, speed 600r / min, power 800KW. September 1998. During the regular switching operation of two fans, the vibration of fan 2 was found to be severe. The radial vibration is almost three times of that of fan 1. Among them, the peak value of No. 4 measuring point is 14.02mm/s, which exceeds the allowable range specified in ISO2372. The temperature measurement records of each measuring point show that there is no obvious change in temperature, and the possibility of local bearing failure is eliminated. The radial wave form of the No. 4 measuring point with the strongest vibration was collected by the vibration pass 903 data acquisition device, and its spectrum was obtained. It is found that it is dominated by power frequency and its double frequency, and the whole spectrum is in the form of "fir tree". It can be inferred that the fan rotor is out of balance. Based on the SDEs expert system diagnosis of vibration communication, it is concluded that: ① the vibration spectrum is dominated by the fundamental frequency component, and the rotor is estimated to have dynamic imbalance or bending. It is suggested that the rotor should be balanced first. If the vibration is suddenly increased, there may be rotor parts or scaling falling off; ② the large vibration is related to the blade or fluid parameters, based on which the balance of the fan impeller is corrected, and after adding the balance weight of 6606g, the vibration drops completely, and the hidden trouble is eliminated successfully.

4 Conclusion

The development of modern science and technology. The mechanical equipment is becoming more and more automatic and complicated, and the degree of precision is also increasing. Condition based maintenance based on equipment condition monitoring and fault diagnosis technology is the necessary condition to improve the modernization level of equipment management and maintenance, and the huge economic benefits will be recognized by more and more coal enterprises.