Reliability modeling of hydraulic system of drum shearer machine

The hydraulic system plays an important role in supplying power and its transition to other working parts of a coal shearer machine. In this paper, the reliability of the hydraulic system of a drum shearer was analyzed. A case study was done in the Tabas Coal Mine in Iran for failure data collection. The results of the statistical analysis show that the time between failures （TBF） data of this system followed the 3-parameters Weibull distribution. There is about a 54% chance that the hydraulic system of the drum shearer will not fail for the first 50 h of operation. The developed model shows that the reliability of the hydraulic system reduces to a zero value after approximately 1 650 hours of operation. The failure rate of this system decreases when time increases. Therefore, corrective maintenance （run-to-t^ailure） was selected as the best maintenance strategy for it.

Reliability and maintainability analysis of electrical system of drum shearers

The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed （iid） and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures （TBF） and time to repair （TTR） data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair （TTR） of this system varies in range 0.17-4 h with 1.002 h as mean time to repair （MTTR）. There is a 80% chance that the electrical system of shearer of Parvade. 1 mine repair will be accomplished within 1.45 h.

Factors affecting thin coal seam shearer drum coal-loading performance by a model test method

To solve the problem of a low coal-loading rate being exhibited by the drum shearer on Chinese thin coal seams,systematic tests and research were performed to study the pivotal factors’influences on drum coal-loading rate using a model test method.The effects of the drum hub diameter,cutting depth,vane helix angle,drum rotation speed and hauling speed on drum coal-loading rate were determined under circumstances of coal-loading with drum ejection and pushing modes,and reasons for these phenomena were analyzed.The results indicate that the influence of the drum cutting depth on the drum coal-loading rate is the most significant.The parameters of hub diameter,drum rotation speed and hauling speed can influence the drum coal-loading rate by cutting the coals’filling rate in the drum.The parameters of vane helix angle and drum rotation speed can influence drum coal-loading rates by influencing the ratio of cutting coals’tangential and axial speed in the drum.The coal-loading rate with drum ejection is clearly higher than that observed with drum pushing.Research in this study can provide support to design the drum structure and select drum operational parameters for a thin coal seam shearer.

Analysis on vertical steering vibration of drum shearer cutting part

The impact of the load on the shearer is mainly transmitted through cutting part.In this paper,in order to get the vertical steering vibration characteristics of the cutting part of the drum shearer,the working condition of coal mining machine is simplified.A simplified vertical steering model and the simplified vibration model of the whole cutting part of shearer are established.The vertical steering vibration process of the cutting unit is simplified into a single freedom and one forced vibration system under harmonic excitation.The dynamic response of the cutting part under sine excitation is obtained by using Matlab/Simulink for modeling and simulation.The influence of the support rigidity and damping of the high oil cylinder on the vertical steering vibration characteristics of the cutting part is analyzed.The results show that the damping of the cylinder can reduce the vibration of the system and the stability of the swing process of cutting the part is improved.

Parameters analysis of shearer drum loading performance

Three drums with different helical angles （15°, 20°, and 25°） were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation speeds （80, 100, and 120 r/min） and different haulage speeds （1.5, 2.0, and 2.5 m/min） in an orthogonal test design. Loaded coal quantity and cutting power of the drum were the responses measured under the dif- ferent conditions. The effect of the parameters was determined by means of the extreme difference method. The significance of the effects was determined by analysis of variance. The results indicate that the effect from changes in the helical vane on loading performance of the drum is the largest in magnitude. The haulage speed has the least affect on loading performance. The helical angle has the least affect on cutting power of the drum. Haulage speed has the largest affect on the cutting power of the drum. 2011 Published by Elsevier B.V. on behalf of China University of Mining ＆ Technology.

Nonlinear multi body dynamic modeling and vibration analysis of a double drum coal shearer

The double drum coal shearer is widely applied for the underground coal exploration in the mining industry.The vibration and noise control are significant factors for the stability design of the double drum coal shearer.In this paper,the vibration properties of a double drum coal shearer are firstly investigated.The horizontal,transverse and torsional vibrations of the motor body and the angle displacements of the rockers are taken into account.The walking units and the hydraulic units are modeled by the stiffness-damping systems.The nonlinear equation of motion of the double drum coal shearer is established by applying the Lagrange’s equation.The nonlinear vibration response of the system is calculated by using the Runge Kutta numerical method.The effects of the shearing loads,the equivalent damping and stiffness of the walking units,the inclination angels of the rockers and the equivalent damping and stiffness of the hydraulic units on the vibration properties of the system are discussed.

ON OPTIMUM DESIGN OF THE SHEARER DRUM

On the basis of the model experiments, a software for optimum design of the shearer drum has been developed, and the main parameters of a shearer drum also have been optimized. The combination of the techniques of optimization with the mod el experiment makes the designing and theoretical systems of the shearer drum more perfect.

THE APPLICATION OF PATTERN RECOGNITION IN THE AUTOMATIC VERTICAL STEERING SYSTEM OF SHEARER'S DRUM

The pressure signal in the lifting cylinder of the shearer is selected as feature signal, its mean-square deviation is extracted as the feature variable in this paper. The authors put forward a new method of recognizing the shearer’s cutting state based on pattern recognition. According to this, the completed controI software produced a satisfactory experiment result on the artificial longwall face in the laboratory, Finally the authors look forward to the prospect of the introduction of the artificial neural network theory into this field.

外投料式滚筒筛分骨料的效率研究

为了提高外投料式滚筒筛分骨料的效率,对其筛分过程进行研究。以(10~40)mm粒度范围的骨料为研究对象,基于离散元理论,利用EDEM建立筛分模型并结合其筛分过程进行模拟仿真,得到在一定条件时,其转速和进料角度对滚筒筛分效率的影响规律:骨料筛分的最佳转速为15rpm,最佳进料角度为150°;通过正交实验模拟,得到了外投料式滚筒筛的滚筒转速、进料角度、进料量三因素对骨料筛分效率的显著性和最佳取值。仿真研究结果可以为外投料式滚筒筛的结构设计及其工艺参数优化提供借鉴和参考,具有较强的工程应用价值。

Radial mixing and segregation of granular bed bi-dispersed both in particle size and density within horizontal rotating drum

Taking simultaneous variations in both particle volume and density into account, the radial mixing and segregation of binary granular bed in a rotating drum half loaded were investigated by a 3D discrete element method. Then, based on the competition theory of condensation and percolation, radial segregation due to differences in particle volume and/or density was analyzed. The results show that if either percolation effect induced by volume difference or condensation effect induced by density difference dominates in the active layer of moving bed, separation will occur. Controlling the volume ratio or density ratio of the two types of particles can achieve an equilibrium state between percolation and condensation, and then homogenous mixture can be obtained. When the percolation balances with the condensation, the relationship between volume ratioand density ratiopresents nearly a power function. Scaling up a rotating drum will not affect the mixing degree of the granular bed so long as the volume ratio and density ratio are predefined.

模块化滚筒好氧发酵反应器设计与试验

针对现有滚筒式好氧发酵反应器存在腔体容积固定不可调、运行能耗高、尾气余热回用难等问题,基于模块化设计理念,研发了一种模块化滚筒好氧发酵反应器,主要由滚筒、曝气系统、余热回用装置、驱动系统和密封连接件等模块单元组成。对模块化滚筒好氧发酵反应器进行堆肥性能试验,结果表明:高温期持续9 d,发酵持续15 d后种子发芽指数达90%以上,各项指标均满足堆肥腐熟和无害化要求。该设计提高了滚筒好氧发酵反应器加工组装效率,扩大了滚筒好氧发酵反应器适用范围,具有规模可调、分段驱动、分级发酵、精准曝气等优点,可为滚筒好氧发酵反应器堆肥技术发展和应用提供支撑。

带式输送机驱动系统的分析与比较

带式运输机在起停运行时存在着刚性撞击和负载起动等情况,会对带式输送机造成损伤,针对此现象,文中采取在大规模的带式输送机上应用软起动驱动系统解决,软起动驱动系统主要采用永磁直驱滚筒、液黏传动、变频器、可控启动传动系统CST和柔性驱动系统FDS等方案。对5种驱动装置的柔性启动机理进行了较为详尽的阐述;通过比较5种驱动系统,分析其优缺点,并对应用于带式输送机的软起动驱动装置所带来的经济效益进行了分析。

投喂频率对陆基圆桶养殖大口黑鲈生长及水体水质的影响

【目的】研究不同投喂频率对陆基圆桶养殖大口黑鲈(Micropterus salmoides)生长性能、水体水质及其微生物群落结构的影响。【方法】本研究开展了2次/天和3次/天两种投喂频率实验。【结果】3次/天组的终末体质量和特定生长率高于2次/天组。投喂频率对水体中氨氮(TAN)、亚硝酸盐(NO2-N)、悬浮物量(SS)和化学需氧量(COD)等指标的浓度均有显著性影响(P<0.05),且2次/天组高于3次/天组。两组养殖水体的细菌群落结构相似,其优势菌门均为变形菌门(Proteobacteria)和拟杆菌门(Bacte-roidetes),优势菌属均为邻单胞菌属(Plesiomonas)和红细菌属(Rhodobacter);对大口黑鲈养殖过程中常见致病菌丰度进行统计,发现3次/天组豚鼠气单胞菌(Aeromonas caviae)的平均丰度(0.08%)显著低于2次/天组(0.14%)(P<0.05)。环境因子与细菌群落结构关联分析结果显示,氨氮(TAN)、总氮(TN)和总磷(TP)对水体细菌群落结构均有显著性影响(P<0.05)。【结论】大口黑鲈陆基圆桶养殖模式中,3次/天投喂频率较2次/天投喂频率具有生长快、养殖水体关键水质指标水平低以及致病菌丰度低的优势。本研究结果可为陆基圆桶养殖大口黑鲈的科学投喂提供实际支持。

器以载道:铜鼓文化在铸牢中华民族共同体意识中的价值逻辑及实践路径

铸牢中华民族共同体意识是习近平总书记提出的重大原创性论断,是维护各民族根本利益和实现中华民族伟大复兴的必然要求。中华民族共同体意识厚植于中华优秀传统文化之中。具有两千多年历史的中国铜鼓不仅是中华民族历史文化变迁的“见证者”,也是中华民族交往交流交融的“记录者”。中华民族共享的文化符号、共生的历史记忆、共有的价值观念都在铜鼓文化中可见一斑。为全面体现、充分发挥铜鼓文化这一中华优秀传统文化在铸牢中华民族共同体意识中的价值和功能,应积极彰显共享文化符号,维系中华民族情感纽带;增进文化互鉴融通,强化中华民族文化认同;打造铜鼓文旅品牌,推动各民族共同富裕。

提升薄煤层采煤机工作效率关键措施研究

针对薄煤层工作面采煤机工作效率低的问题,提出了采煤机大功率化、合理确定滚筒大小、明确滚筒旋转方向、缩短检修维护时间的解决措施。研究表明,优选大功率薄煤层采煤机、合理选择滚筒直径,可显著提升采煤机工作效率;明确滚筒旋转方向为内旋,可降低采煤机运行阻力,有利于提升工作效率;开发基于自润滑技术的铰接轴套和轴承,可减少检修时间,提高采煤机开机率,提升工作效率。

综采面无线采煤机截煤跟踪降尘系统的设计

为了有效地解决现有综采面采煤机截煤跟踪降尘系统各设备间由于有线连接的安装难度大、线路易扯断、维护繁琐等问题,设计了一种基于无线通信的采煤机截煤跟踪喷雾系统。阐述了系统的总体结构,介绍了采煤机定位发射器和定位接收器的设计原理,重点介绍了喷雾控制箱的硬件设计、软件设计以及低功耗设计过程。通过在实验室搭建模拟系统,进行了喷雾功能实验,结果表明:该系统各设备之间采用无线通信,减少了中间的线路连接,安装及维护简单,系统能够按照设定的系统喷雾参数,控制电动球阀的开启和关闭,实现采煤机滚筒附近的喷雾降尘。

基于矿鸿操作系统的采煤机控制系统架构研究

研究了基于矿鸿操作系统的采煤机控制系统架构。首先介绍了煤矿智能化发展背景和传统采煤机系统存在的问题,针对现有问题提供了解决思路。然后着重探讨了矿鸿操作系统架构设计和特性、矿鸿在采煤机控制系统架构中的应用,分析了矿鸿操作系统在采煤机领域的潜力和优势。最后展望了矿鸿在采煤机控制系统的应用前景、技术发展方向及存在的问题和挑战。

基于参数迁移的摇臂传动系统跨工况故障诊断算法

摇臂传动系统在采煤机中扮演着至关重要的角色,直接影响着煤炭生产的效率。针对跨工况迁移故障诊断难题,研究发现源域和目标域的故障数据特征分布相似。为此,提出了一种基于参数迁移的故障诊断模型。该模型采用全局均值池化的迁移卷积神经网络(TCNNG)模型,能够自动从源域工况数据中提取特征信息。通过参数迁移加微调的策略,将诊断知识参数从源域成功迁移到目标域,显著提高了模型在不同工况下的故障识别率和泛化性能。

高功率密度采煤机摇臂加载油温预测方法及试验

分析了高功率密度采煤机摇臂产热和散热因素及计算方法,建立了热平衡方程,根据热平衡方程预估了摇臂加载试验过程中的油温,通过计算和试验分别得到了摇臂空载和加载时在不同加油量下摇臂温升与时间的变化曲线。结果表明,齿轮的啮合、轴承摩擦及直齿轮搅油在摇臂产热中占据主导地位,而摇臂表面散热、内部件吸热及冷却水是散热的主要途径。设计过程中可以采取措施从上述几方面减少产热及扩大散热。该方法可预测采煤机摇臂加载油温并可推广应用。

恶劣综采工况条件下的采煤机摇臂散热设计研究

简述了在采煤机设计过程中对恶劣综采工况中工作倾角较大、煤岩硬度较硬、截割功率大且结构紧凑限制条件下的摇臂热功率的计算,分析了该工况中摇臂简化为复杂齿轮箱思路下的热功率计算、散热途径和热平衡点,提出了摇臂内部结构改进及增加外置冷却装置的散热设计方案,并验证了满载试验条件下摇臂截割热平衡温度不超过90℃的方案可行性。