矿用液压支架掩护梁结构强度优化的研究

在整个采煤过程中,液压支架作为煤矿开采的支护设备,它的高强度性和高安全性直接决定了煤矿开采作业的生产安全。根据目前对液压支架整体结构研究和实际采煤作业中发现掩护梁是液压支架整体较薄弱部位,特别是在顶梁受扭转载荷时更为突出。利用Hyperworks软件针对扭转载荷下的掩护梁进行了静力学分析和拓扑优化分析,在此基础上提出了结构优化方案,并对优化方案进行了相同工况下的静力学分析。对比优化方案的分析结果显示方案四使最大应力减小了24.46%,同时重量降低194 kg,最大位移也有所降低,优化结果最理想。对液压支架的整体优化提供了技术支持,完成了强化结构的同时液压支架总体轻量化的设计目标。     

磁弹性应力传感器检测支架载荷试验研究

液压支架是煤矿开采中的支护设备,其载荷的检测问题一直是没有得到很好解决．根据液压支架的受载特点,提出了应用磁弹性原理检测其外载荷的方法;根据支架的结构特点,研制了适合测量支架上不同受力构件的十字桥式磁弹性应力传感器,并以此对单体液压支柱和模拟连杆试件进行了加载检测试验．结果表明,液压支柱及连杆在不同载荷下,传感器的输出信号与载荷之间具有近似线性关系的规律性．进而讨论了用磁弹性应力传感器检测支架载荷的可行性．     

固体充填开采直接顶位态控制机制及工程案例

基于充填开采岩层移动特征与实际采场中的8种典型覆岩载荷形式,建立了四柱充填采煤液压支架顶梁的平衡方程,分析了不同覆岩载荷形式下立柱的受力状态,结合工程实测确定支架顶梁最优载荷形式为二次曲线;构建了充填采煤液压支架与充填体协同控顶的力学方程;分析了直接顶位态的主要影响因素,揭示了固体充填开采直接顶位态控制机制,即充填体弹...     

液压支架工况与特性的浅析

液压支架作为国内外现代化矿井的重要标志,本文主要分析液压支架的各种工况和特性,对于立柱的工作过程和立柱的压力监测的技术方法展开讨论研究,对于今后液压支架发展设计具有一定作用.     

ZY6400/21/45型液压支架底座强度分析和结构优化

底座是液压支架非常重要的承载原件.依据液压支架国家标准GB 25974. 1—2010《煤矿用液压支架第1部分:通用技术条件》,选取两种危险工况对支架进行有限元分析,根据静应力分析结果观察整机应力分布状况和位移变化趋势,从中发现液压支架存在的初始设计问题,最后着重对底座的强度进行优化,使支架的整体强度得到了提高.     

液压枕的设计计算

液压枕是量测压力的一种仪器,在矿山可用来测定巷道支架,工作面支架等的承载大小。液压枕也可以作为岩体试验的加压设备。液压枕可根据不同用途进行设计。过去曾设计和使用过测定巷道支架载荷用的液压枕。本文介绍的液压枕,根据测定液压自移支架的外载分布而设计的。结构与其他形式的液压枕基本相同,只是增加一个压力传感器。现已由我院工厂投入小批量生产,已在现场试用。     

弹性底板上的液压支架整体尺寸参数优化

基于弹性地基梁理论,建立了弹性底板上的液压支架底座受力分析模型,以前后连杆力最小、结构尺寸最小、掩护梁弯矩最小、支护效率最高、弹性底板比压最小为5个优化目标函数,通过序列二次规化法对液压支架的整体尺寸设计参数进行优化,实现了不同底板状况下的整体尺寸参数优化,基于MATLAB/GUI可视化编程,实现了程序的可视化.算例分析表明,将底板比压作为优化目标函数对液压支架整体进行优化,在结构尺寸变化不大的前提下,优化结果不仅能满足设计要求,而且力学特性有较大的改善,前后连杆轴力、底板比压、掩护梁弯矩4个参数较优化前平均减少了31.95%.     

充填采煤液压支架受力分析与运动学仿真研究

根据充填采煤液压支架结构原理及控顶作用,建立了支架顶梁的力学模型,分析得出了顶梁受力情况及3排立柱受力之间的关系;运用Pro/E软件对支架进行三维建模和运动学仿真分析,模拟出主要部件的运动过程,得出各主要部件在工作过程中的运动特征曲线,并对支架参数进行了校核.基于以上分析结果设计制造了ZZC8800/20/38型充填采煤液压支架,支架前、后排立柱受力分别是中立柱支架受力的4.1倍、4.6倍.该支架在平煤十二矿成功应用表明受力分析及设计是科学合理的.     

矿用液压支架强度分析

对某型矿用液压支架进行结构强度分析和实验对比。针对煤矿用液压支架实验标准要求的几个工况进行分析,选取顶梁偏心加载、顶梁扭转加载和顶梁两端加载等3个行业比较关心的工况进行有限元计算;针对这3种工况,采用电测法测试了台架试验时若干测量点的应力;通过有限元计算的应力值与试验测量应力值对比,发现两者误差较小。该计算分析方法为产品的研发提供了较可靠的依据。     

ZY6400／21／45液压支架推杆的强度分析及结构优化

针对ZY6400／21／45液压支架推杆进行研究,在建模的基础上,对液压支架推杆的受力状况进行了有限元分析,从而得出了推杆的应力、位移、应变及安全系数的分布情况,进而对其结构进行了优化,为液压支架的设计和分析提供了理论依据．     

Key technologies and engineering practices for soft-rock protective seam mining

Severe gas disasters in deep mining areas are increasing, and traditional protective coal seam mining is facing significant challenges. This paper proposes an innovative technology using soft rock as the protective seam in the absence of an appropriate coal seam. Based on the geological engineering conditions of the new horizontal first mining area of Luling Coal Mine in Huaibei, China, the impacts of different mining parameters of the soft-rock protective seam on the pressure-relief effect of the protected coal seam were analyzed through numerical simulation. The unit stress of the protected coal seam, which was less than half of the primary rock stress, was used as the mining stress pressure-relief index. The optimized interlayer space was found to be 59 m for the first soft-rock working face, with a 2 m mining thickness and 105 m face length. The physicochemical characteristics of the orebody were analyzed, and a device selection framework for the soft-rock protective seam was developed. Optimal equipment for the working face was selected, including the fully-mechanized hydraulic support and coal cutter. A production technology that combined fully-mechanized and blasting-assisted soft-rock mining was developed. Engineering practices demonstrated that normal circulation operation can be achieved on the working face of the soft-rock protective seam, with an average advancement rate of 1.64 m/d. The maximum residual gas pressure and content, which were measured at the cut hole position of the protected coal seams (Nos. 8 and 9), decreased to 0.35 MPa and 4.87 m³/t, respectively. The results suggested that soft-rock protective seam mining can produce a significant gas-control effect.     

综放全煤平巷锚杆支护模拟试验研究

根据“巷道围岩松动圈支护理论”,以南屯矿３上 煤层综放工作面全煤平巷围岩条件为基础,对不同动压系数、侧压系数、锚杆支护参数条件下,锚杆支护巷道围岩应力分布、围岩变形及巷道破坏规律进行了模拟试验．试验证实,矩形煤巷顶板中存在一个卸压区,巷道两帮和角部区域围岩破坏严重,是支护的重点部位．锚网支护能有效控制采动压力影响下全煤巷道围岩的稳定性．试验得到的结论对于综放全煤巷道锚网支护设计和应用具有指导意义．     

Design of hydraulic shift mechanism for AMT vehicles based on the collaborative optimization method

Based on multidisciplinary design optimization (MDO), a new design method is put forward for hydraulic shift mechanism of heavy-duty vehicle automated manual transmission (AMT). Taking a shift cylinder for example, the collaborative optimization (CO) method for the design problem of a cylinder is devided into one system level design optimization problem and three subsystem level design optimization problems. The system level is an economic model and the subsystem level is mechanics, kinetics, and a reliability model. Application of the multidisciplinary design optimization software iSIGHT modeling and solving, optimal solution of the shifting cylinder CO model is obtained. According to the optimal solution, oil cylinders are machined out and installed on the gearbox of an AMT system for the bench cycle shift test. The results show that the output force and action speed of the optimized mechanism can meet requirements very well. In addition, the optimized mechanism has a better performance compared to the structure of the traditional design method, which indicates that the CO method can optimize the design of hydraulic transmission.     

排气管焊接夹具夹爪的优化设计

利用有限元软件ANSYS Workbench对排气管焊接夹具夹持机构的夹爪进行静力学分析,得到夹爪的变形和应力分布情况。在夹爪满足排气管焊接中强度和刚度要求的前提下,对夹爪采用多目标优化中的响应面优化法对其进行尺寸优化,首先建立夹爪优化的数学模型,设置目标函数和约束条件,然后将夹爪各个尺寸进行参数化,通过计算得到夹爪最优设计尺寸。再采用变密度法对夹爪结构进行拓扑优化,以减轻其质量。将夹爪优化前后的变形和应力分布情况进行比较,结果显示优化后夹爪在应力和变形满足设计要求的情况下,夹爪的重量减轻了18.2%。     

基于智能算法的汽车气动外形参数多目标优化

为了对汽车外形进行优化设计,利用CFD软件与智能算法相结合的方法,以在天窗微开高速行驶状态下的汽车为优化的对象,选取气动阻力最小、气动升力为0、天窗后缘压强最小为`优化目标,以汽车关键外形参数为设计变量,对汽车气动外形进行多目标优化设计.同时,应用了数据挖掘技术评价设计变量与3个目标函数的影响关系,选取优化后的最佳关键参数制作汽车模型并进行风洞试验验证.研究结果表明:通过遗传算法优化的车身外形,在其他设计目标满足要求的条件下成功地将阻力系数降低了9.5%,并通过风洞试验验证了该智能算法结果的准确性.基于智能算法的汽车气动外形设计具有指导意义与实际应用价值,为汽车气动外形的多目标优化设计提供了一种高效、精确、可靠的先进优化方法.     

Hydraulic support crushed mechanism for the shallow seam mining face under the roadway pillars of room mining goaf

While the fully-mechanized longwall mining technology was employed in a shallow seam under a room mining goaf and overlained by thin bedrock and thick loose sands, the roadway pillars in the abandoned room mining goaf were in a stress-concentrated state, which may cause abnormal roof weighting, violent ground pressure behaviours, even roof fall and hydraulic support crushed(HSC) accidents. In this case,longwall mining safety and efficiency were seriously challenged. Based on the HSC accidents occurred during the longwall mining of 3-1-2 seam, which locates under the intersection zone of roadway pillars in the room mining goaf of 3-1-1 seam, this paper employed ground rock mechanics to analyse the overlying strata structure movement rules and presented the main influence factors and determination methods for the hydraulic support working resistance. The FLAC3 D software was used to simulate the overlying strata stress and plastic zone distribution characteristics. Field observation was implemented to contrastively analyse the hydraulic support working resistance distribution rules under the roadway pillars in strike direction, normal room mining goaf, roadway pillars in dip direction and intersection zone of roadway pillars. The results indicate that the key strata break along with rotations and reactions of the coal pillars deliver a larger concentrated load to the hydraulic support under intersection zone of roadway pillars than other conditions. The ‘‘overburden strata-key strata-roadway pillars-immediate roof" integrated load has exceeded the yield load that leads to HSC accidents. Findings in HSC mechanism provide a reasonable basis for shallow seam mining, and have important significance for the implementation of safe and efficient mining.     

Roadway failure and support in a coal seam underlying a previously mined coal seam

The influence of an upper, mined coal seam on the stability of rock surrounding a roadway in a lower coal seam is examined. The technical problems of roadway control are discussed based on the geological conditions existing in the Liyazhuang Mine No.2 coal seam. The stress distribution and floor failure in the lower works after mining the upper coal is studied through numerical simulations. The failure mechanism of the roof and walls of a roadway located in the lower coal seam is described. The predicted deformation and failure of the roadway for different distances between the two coal seams are used to design two ways of supporting the lower structure. One is a combined support consisting of anchors with a joist steel tent and a combined anchor truss. A field test of the design was performed to good effect. The results have significance for the design of supports for roadways located in similar conditions.     

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.