Applied Mechanics and Materials Vol. 345 (2013) pp 108-111 Online available since 2013/Aug/08 at www.scientific.net © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.345.108
Development and Application of Portable Mining Vibration Recorder GuangHui XUE 1, 2, a,*, Jun Zhang 1, b, XiaoDong Ji 1, c, XinYing ZHAO 1, d 1
School of Mechanical, Electronic and Information Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China 2
SEDTAPP, The Pennsylvania State University, University Park, State College, PA, 16802
a
[email protected],
[email protected],
[email protected],
[email protected]
*GuangHui XUE (1977- ), PhD, Associate Professor, research interests: mining machinery, condition monitoring and fault diagnosis, testing techniques and intelligent instruments. E-mail:
[email protected]; Office Phone: (+8610)62339328, FAX: +86+10+62339089. Keywords: vibration measurement; underground coal mine; condition monitoring and fault diagnosis; ARM; recorder
Abstract: It has been a bottleneck for the application of vibration-related techniques in the coal mine that the vibration data cannot be acquired due to lack of mining vibration instrument. This paper discussed the development of a portable mining vibration recorder, introduced its overall scheme, as well as its hardware and software design in detail. The developed recorder is a coal mine intrinsically safety instrument based on ARM system, with features of 4 channels analog input, 2GB large volume storage memory, 250kHz sampling frequency, no less than 3.5h fullpayload continuous working time with battery supply, fitted to record and deposit the vibration signal of the equipment in atmospheres with methane and coal dust explosive mixture. The authors carried out a series of testing application in ChengZhuang coal mine. The experimental results show that the data acquired by the recorder is true and valid. Study provides an instrumental basis of apparatus to carry out the supervision of machine based on vibration detection in coal mine. Introduction Vibration techniques have been widely studied in lots of fields in coal mine, especially in the area of coal mine safety [1], equipment vibration monitoring and analysis [2], device condition monitoring and fault diagnosis [3]. Vibration techniques and its application in coal mine have been focused on by the coal mine scientist and technician and one of research interests. The coal mine frequently goes through threatens coming out from natural disaster, such as coal dust and gas outburst potential and sudden inflow of water or fire. Due to the severe environments and the existence of explosive gas, high requirements for the instruments used in coal mine, especially electrical apparatuses are put forth, which lead to the absence of vibration measuring device or low performance apparatuses that only have a few simple functions, thus restrain the application of vibration techniques in coal mine. To solve the above problem, many scholars have conducted a lot of studies [4-6]. The author and his team members also did series of work and developed several vibrating devices to acquire the vibrating data under coal mine [7, 8]. This paper depicts the development and its application of new generation coal mine vibrating recorder. Overall Designs Scheme With the Xscale core based on ARMv5E, the general scheme for the portable recorder was suggested, shown in Fig. 1, which consists of embedded board with PXA27x series embedded processor, data acquisition card (DAC card), vibration acceleration sensor integrated with charge amplifier circuits and peripheral devices (LCD, key board, SD Memory card and power module).
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Vibration acceleration sensor #1
Vibration acceleration sensor #1
Vibration acceleration sensor #1
Signal conditioning module
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Power module
Data acquisition card
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Data transfer interface
LCD display
PXA270 embedded board
Key board
PC104 Bus
SD memory card
Fig. 1 Overall solution diagram Hardware Modules Design ARM Embedded Mainboard. Considering the requirement of low power consumption for the electrical devices used under coal mine, ARM8019 embedded main board was selected for the recorder infrastructure. The board is an industrial level embedded mainboard with PC104 bus specification and with features of extreme high cost performance, compact structure and size, and low power consumption (only 5W whole board power consumption). The selected board adopts the Intel Xscal series PXA270 CPU with up to 520MHz main frequency, can work well under ultra wide temperature range of -40°C ~+85°C without fan, and runs embedded Linux or WinCE operation system. Data Acquisition Card. For matching and compatibility with the selected mainboard, a PC104 bus compatible data acquisition card is chosen, which has of 250 kHz total sample frequency, 16bit sample solution. The DAC card has continuous (asynchronous) and group (pseudo synchronous) acquisition mode. Vibration Acceleration Sensor. Built-in ICP piezoelectric acceleration sensor has the lots of good features, such as small size profile, light weight, strong interfere-resistant ability and able to connect with longer cable than the no built-in ICP sensor. So the author adopted this type sensor for transduction of the original signal to electrical signal. Allowing for the atmosphere circumstances of damp, gas and heavy coal dust under coal mine, coal mine flame-retardant cable is used instead of standard cable connecting sensor with main part of the recorder, and the connector of the sensor cable is replaced with aviation connector with features of waterproof and dustproof. The sensor can be amounted on the point from where you want to obtain the vibration signal of equipments to be detected with magnetic suction seat or screw. Different orientation vibration signal can be achieved via the sensor attached with a universal joint to change the orientation of vibration measuring. Power Module. The power supply of the recorder was divided in two columns of circuit units, switching automatically, namely internal power unit and external unit. When the external unit can be accessed, the recorder uses the external power supply and charge the battery pack at the meantime; otherwise, the recorder uses internal unit with battery pack to supply itself if the external does not exist or cannot be available. The power module consists of battery pack, charge circuit, power switching circuit and sensor exciting circuit the acceleration sensor needs. The battery pack is comprised of 6 cells series chargeable NI-MH battery with capacity of 4500AH, sealed together with epoxy resin, to make sure that the work time of recorder is not less than 3.5 hours. Industry Application At the 2318 coal face in Chengzhaung coal mine, a series of vibration testing experiments were conducted on the gearbox of belt conveyor using the developed recorder and obtained lots of field data. Fig. 2 shows the acquired vibration signals time waveform and its power spectrum at a time.
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The shock components can be seen from the time waveform obviously. The gear-mesh frequency of 24.4Hz for the gearbox input shaft and its harmonic components can be seen distinctly on the power spectrum figure and the harmonic components play a predominant role. It can be inferred that there were some severe wear-out flaws in the gear on the input shaft (its mesh frequency is the same to the components of 24.4Hz in the power spectrum). To verify the above judgments, the gearbox was dismantled after transported to ground surface. Fig. 3 shows some pictures for the wear gear on the gearbox input shaft.
(a) Time waveform
(b) Power spectrum Fig. 2 The time waveform of the acquired vibration signal on the gearbox in coal mine using developed recorder and its power spectrum
Fig. 3 The wear condition of the gear on the gearbox input shaft Conclusions （1） The developed recorder is an intrinsic safety mining instrument based on ARM system with features of small size, light weight and portability, can be used in the explosive atmosphere with methane, coal dust, such as coal mine, to implement the acquisition, recording and storing of the vibration signal on the working equipments under coal mine. （2） The main technic indexes for the developed recorder are as following: 1) explosive proof type of intrinsic safety; 2) 4 channels; 3) total sample frequency of 250kHz; 4) data storage
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capacity of 2GB (can be expanded to 4GB); 5) attached 4 vibration acceleration sensors with the sensitivity of 5mV/ms-2 and frequency range of 1-10kHz; 6) full-payload continuous operation time of not less than 3.5h. （3） A series of vibration testing experiments were conducted on the gearbox for the belt conveyor in coal mine using the developed recorder and obtained lots of field data. Severe wear-out flaws were inferred after the analysis of field data. The overhaul results indicated that the correctness of the analysis and the validity of the data acquired by the recorder. Acknowledgements The study in this paper was supported by “the Fundamental Research Funds for the Central Universities (Grant NO: 2009QJ16)”. References [1] LI Xiang-chun, NIE Bai-sheng, HE Xue-qiu. Mechanism of coal and gas bursts caused by vibration [J]. JOURNAL OF UNIVERSITY OF SCIENCE AND TECHNOLOGY BEIJING, 2011, Vol. 33(2) ：149-152. [2] ZHANG Li-rong. Analysis of Vibration of Gear Box of Hoist [J]. Coal Mine Machinery, 2011, 32(10): 274-276. [3] JIA Hong-gang, LI Zhen, CAO Hong. Application of Vibration Monitoring Analyzer in Fault Diagnosis of Coal Mine Electromechanical Equipments [J]. Industry and Mine Automation, 2011, 37(8): 11-13. [4] LI Chuan-tao, HAO Wei, HAO Wang-shen, et al. Study on Coal Gear Box Status Predictive Method Based on Band Vibration Severity and ARIMA [J]. COAL MINE MACHINERY, 2011, 32(4): 251-253. [5] XUE Guanghui, ZHAO Guorui, ZHU Shigang, et al.. Express detection method on the crack flaw of large vibrating screen lower beam based on MMMT and ET [J], Journal of china coal society, 2010 Vol.35 (7) : 1215-1218. [6] YAN Zhixin, PENG Ningbo, JIANG Ping, et al... Research about blasting vibration safety criteria [J]. Journal of china coal society, 2011 Vol.36 (8): 1281-1284. [7] XUE Guang-hui, WU Miao, ZHOU Bin. Development of mine portable digital recorder [J]. COAL SCIENCE AND TECHNOLOGY, 2004, 32(5): 52-54. [8] ZHOU Li-zhi, ZHOU Peng-chong, XUE Guang-hui, et al. Study on multi-channel data collection system in underground mine [J]. COAL ENGINEERING, 2006, 19(1): 71-72.
Advanced Research on Mechanical Engineering, Industry and Manufacturing Engineering III 10.4028/www.scientific.net/AMM.345
Development and Application of Portable Mining Vibration Recorder 10.4028/www.scientific.net/AMM.345.108
