采用液控单向阀的平衡回路实验装置设计【含CAD高清图纸和文档资料】
收藏
资源目录
压缩包内文档预览：(预览前20页/共35页)
编号：32223134
类型：共享资源
大小：1.41MB
格式：ZIP
上传时间：2019-12-18
上传人：好资料QQ****51605
认证信息
个人认证
孙**（实名认证）
江苏
IP属地：江苏
45
积分
- 关 键 词：
-
含CAD高清图纸和文档资料
采用
单向阀
平衡
回路
实验
装置
设计
CAD
图纸
文档
资料
- 资源描述：
-
【温馨提示】====【1】设计包含CAD图纸 和 DOC文档，均可以在线预览，所见即所得，，dwg后缀的文件为CAD图，超高清，可编辑，无任何水印，，充值下载得到【资源目录】里展示的所有文件======【2】若题目上备注三维，则表示文件里包含三维源文件，由于三维组成零件数量较多，为保证预览的简洁性，店家将三维文件夹进行了打包。三维预览图，均为店主电脑打开软件进行截图的，保证能够打开，下载后解压即可。======【3】特价促销，，拼团购买，，均有不同程度的打折优惠，，详情可咨询QQ：1304139763 或者 414951605======
- 内容简介：
-
毕业设计（论文）中期报告题目：采用液控单向阀的平衡回路实验装置设计 系 别 机电信息系 专 业 机械设计制造及其自动化 班 级 姓 名 学 号 导 师 2013年 3 月 22 日设计（论文）进展状况 （1）查阅资料并完成一篇3000字以上的关于液压系统的外文翻译：盾构机的压力调节液压系统的仿真分析。 （2）回路采用了液压缸加载，对原理图进行了进一步的完善，具体如下图所示。 （3）通过初步计算，基本完成方案设计。主要完成了液压元件的初步估算，管道以及管接头的初选，油箱的尺寸选择，液压缸的设计以及各个零部件的选择。具体所选液压元件的型号规格如下表。表1 液压元件明细表序号名称型号额定流量（Lmin）调定范围（MPa）其它1单叶片定量泵YB1-10152电动机Y-90S-2三相异步电动机额定功率1.1Kw，额定转速1400r/min3滤油器（线隙式）XU-J168016通径12mm4溢流阀YF3-10B630.56.3重量1.6kg5液控单向阀YAF3-10B636单向阀AF3-Ea10B407减压阀JF3-10B630.56.3重量2.85kg8节流阀LF3-E10B100重量4kg9二位四通电磁换向阀24F3-10B6010三位四通电磁换向阀34F3-10B60表2 液压缸和油箱设计的基本尺寸 液压缸：最大外负载F=3000N，工作腔压力P1=2.0Mpa，回油腔背压P2=0.2Mpa，缸内径D=50mm，活塞杆径d=25mm，液压缸的最大流量为10.3L/min。油箱 ：液压油箱的有效容积V=30L，计算选得BEX系列液压油箱，型号为BEX-63A，长：宽：高=550：450：600。 （4）进入技术设计阶段：装配图（包括：实验台总装配图，背后油道管路图），和零件图（包括实验台焊接支架构成图，油箱焊接组件图，液压缸零件图以及其他各部分零件图）。现已基本完成了实验台总装配图的绘制和一些零件图的绘制等。装配图如下图所示。存在问题及解决措施 （1）在管道选取上考虑不够全面，选择了可用于低压系统的尼龙管。解决的方法是也要考虑其连接时的美观度，所以选择钢管。（2）在原理回路中工作缸和加载缸两活塞杆之间的连接不太完善，不能很好的实现回路动作。解决的方法是在两活塞杆之间应用连接器将二者连接以增加工作时运动的连贯性，使回路运行更加有效。 （3）在实验台装配图、立式泵安装部分的绘制上，会出现一些不合理之处，在老师的悉心指导下正在逐步一一改进。 （4）液压缸的设计是否还需要加装缓冲装置和排气装置，加装对液压缸的安装形式是否有影响。解决的方法是由于此次实验装置系统设计属于低压系统，先暂时按不加处理，液压缸选取底面脚架安装形式、进出油口选螺孔连接，最后校核时再进一步详细分析。后期工作安排 后期的工作安排：后期的主要工作重点还是放在工程图的绘制，并且进一步完善装配图、加紧时间完成所有零件图的绘制。并同时撰写论文，最后对整个油路进行热温升校核，完成全部技术设计。后期的时间安排如下：911周完成全部技术设计并校对所有图的绘制；1213周撰写毕业设计论文；14周，答辩前准备。 指导教师签字： 年 月 毕业设计(论文)外文资料翻译 系 别： 机电信息系 专 业： 机械设计制造及其自动化 班 级： 姓 名： 学 号： 外文出处：Front.Mech.Eng.2011,6(3):377382附 件： 1. 原文； 2. 译文 2013年03月盾构机的压力调节液压推力系统的仿真分析高等教育出版社和斯普林格出版社柏林海德堡2011摘要：液压推进系统在盾构掘进机中是一个重要的系统。推力气缸压力调节推力系统在隧道开挖过程中有重要作用。为了研究系统的特点，在本文中,液压推进系统被解释说是和一个相应的仿真模型进行优化。压力调节某组的缸不会影响其他组缸的运行。泵位移对压力调节和供油流量适应系统的需求有很大的影响。一个恰当的例子解释了如何模拟隧道开挖期间压力调节工作。关键词：隧道，液压推进系统，压力调节,仿真1 介绍盾构机是一种用于地下隧道开挖的大型和复杂的机器。它是用于建设工程，如地下铁路、城市管道、海底隧道等等。液压技术是广泛应用于盾构掘进机。例如,它是用于推力系统,刀盘驱动系统,螺旋输送机,段安装工等。隧道开挖工作的研究已开展。杉本和斯顿在力学分析基础上构建了一个隧道开挖理论模型1,其仿真结果与观测数据吻合的较好。玛雅和罗德里格斯使用离散数值模型分析了基坑开挖过程，并对一些推力和转矩也进行了研究3。许等人在隧道开挖研究中也已经发现一些工作参数之间的关系 4，但只有少数研究已经完成液压系统。胡等人也做了一些在推力系统的机器上的工作。压力和流量复合控制也被其研究5。文献 5 不同的系统研究。推力系统压力的调节是通过使用这种调节的简化的仿真模型和案例的研究进行了讨论。2 推力系统推力系统是盾构掘进机的重要组成部分。该系统由动力单元(电机和液压泵),液压阀,液压缸作为执行机构。推力液压缸的数量通常是16或32。如果个人控制液压缸的应用,高数量的比例控制阀和压力传感器是必需的。此外, 在开挖时机器操作员必须控制16或32压力参数，个人控制是十分复杂和昂贵的。如今,推力气缸通常分为四个或五个组,四组安排更常见。四组缸分为A组、B组、C组、D组,对应到右区域,低区、左区和上区。四组缸的比例ABCD通常是4543,见图1。在B组需要更多的缸来计数较低的区域的切削热和高压力。如果他们是在同一组，液压油在不同缸中发挥作用都是相同的。在这种情况下,只有四个比例控制阀门是必需的, 机器操作员只需要控制四个压力参数。在隧道开挖时，液压缸用高压液压油产生推力时推动机器前进。机器操作员可以调整液压压力的推力来使气缸实现转向控制和机态调整。推力过程结束后,段安装将组成一个新的环境的隧道。当一段座落,对应缸延伸。在段安装中这些气瓶发挥作用，用小力来完成段安装过程。3 液压回路和建模推力系统液压回路如图2。该系统主要由一个可变位移泵1,减压阀2、换向阀3、四减压阀4和十六缸液压缸7。泵的位移量正比于输入信号。当系统过载时，泄压阀和换向阀是用来控制扩展运动或收缩运动。减压阀是最重要的组成部分,用于调整液压缸的压力。当气缸是扩展的,高压油从液压泵1,然后流经换向阀3,减压阀4,单向阀5,开/关阀6,最后进入后室的液压缸7。回压油流出7缸的有杆腔,然后通过定向控制阀门3回油箱。当气缸缩回,油流经换向阀3, 然后进入液压缸7的有杆腔。背部压力油流出后室,然后通过开/关阀6,单向阀8,换向阀3,最后进入油箱。商业软件AMESim作为仿真分析工具。为了简化模型，两组液压缸（通常是左区和右区）被进行分析。通过使用这两个区域，模拟盾构机可能的转向运动。仿真模型如图3所示。软件所提供的所有的液压模型除了减压阀的正常模式，是建立一个“超级元件”合成的常用的几种模型。阀门提供了更多的细节不仅有工作参数，而且还有内部结构。在盾构掘进机工作时，可变位移泵与比例位移控制泵具有相同的功能，泵的位移量与输入信号成正比。缸负荷模型的三部分是:土压力、摩擦,力所引起的推力运动。土压力施加在本机的铣头和衬里上。压力施加到刀头影响推力运动,压力在衬里可以忽略。摩擦阻力对衬里的机器引起的土压力是相当大的,占一半以上的推力。然而,在基坑开挖过程时压力和摩擦力几乎保持不断。因此,这两种力量都被设置为常数的模型，土压力设置输入信号的负载模型和摩擦中设置质量模型之间有一个线性关系，即推进速度和推力的关系,见图44。黑星点代表实验结果68%的开放率,白色的方形光点代表结果36%开放率，每一个实线显示了推进速度和推力的线性关系。在广州地铁建设的3号线所显示的数据很好的体现了这个线性关系 6。 一个更大的推力导致更高的推进速度。这是因为更大的力引起较大的刀具进给速度, 在固定的时间间隔内更多的土壤将被切断。为了推动机器前进，这个推力应大于土压力施加到刀头连同摩擦力。如果推力不是足够大,机器将不会进步。在图3中,有一个死区在负荷模型。在死区中，推力是不足以推动机器前进；比如像参考文献 6 这种情况。虽然机器是前进的,但增加了推力将导致增加推进速度，这个实验结果应用于负荷模型。压力调节决定队伍的开挖所以方向机是影响压力分布的推力缸。机器操作员可以通过调整压力缸组控制机器的姿势。如果相应设置的压力调节这台机器可能引导左或右,或提前沿着小角边。通常,隧道尽头的开挖,隧道轴线之间的差异和实际设计隧道轴线应不超过20毫米。否则机器操作员必须重新调整机器推进轴。因此, 在隧道开挖时压力调节是非常重要的函数。4 仿真仿真参数如表1所示是从南京地铁的建设中所使用的盾构机获得的。左、右推力组用于仿真，十六液压缸减少到八,63 cc /启最大位移泵应减少到31.5 cc /启。缸的活塞直径是300mm,杆直径是240mm。无论是左或右推力组,每个都包含四个液压缸,简化为一个具有相同的工作区域与原缸组的液压缸。因此, 模拟缸的活塞直径和杆直径分别是600和480毫米。当机油压力大约是8 MPa,供应约9200 KN的推力,机器开始移动。参考7,就是指摩擦力占53.5% -73%的推力。因此,摩擦力是设定在6000 KN,大约65%的推力。剩下的3200 KN施加在铣刀头隧道开挖中。表1 主要仿真参数项 设定值泵最大位移30 cc /启释放压力35.3 MPa名义上的泵速1500启活塞气缸直径600毫米杆气缸直径480毫米力对铣刀头3200 KN摩擦力6000 KN 4.1 压力调节在这种情况下转向控制是模拟的。两个液压缸最初设置为14 MPa。右缸应该高于左缸（P右）。P左应该保持在14 MPa。P右设置为20 MPa。仿真结果显示在图5和6。P右调整到20 MPa为步进信号。在图5,弹簧质点系统的试点阶段有一个小超调的压力。过冲的质量弹簧系统的超调量会引起的出口压力，当P右、P左脉冲调整,调整后略有增加。入口压力的突然改变首先会造成相同脉冲的出口压力。由于试点阶段的频率响应不够高，在试点阶段机构开始调整阀的开口面积，出口压力下降至设定值。P左的增加可能是由于泵出口流量增加引起的。泵出口流量接下来将会讨论。这个小压力差不会影响隧道开挖。左转向运动进行了，更高的推进速度达到右侧，如图6所示。4.2 泵位移调整当压力进行调节时，泵的位移应进行调整。压力调节操作在先前的例子中已体现，以下三个案件分别来解释此问题，。 案例1:位移保持在大约75%，结果显示在图7。 P右调整到20 MPa，实现压力调节。然而,泵出口压力在35.3 MPa,这意味着系统过载和泄压阀打开。由流动引起的功率损耗是相当大的。案例2:位移保持在大约50%，结果显示在图8。泵压力敏感负载压力。然而,推力压力不能调整到20 MPa因为供油量是不足的。更高的推力压力会导致更高的推进速度,这意味着缸需要更多的流量，在压力调节无效的这种情况下。 案例3:位移是设定在50%,然后压力调节到75%，结果显示如图9。 没有过载。泵的出口压力与负载压力敏感。推力压力可以调整到20 MPa，这是因为泵位移是自适应系统，一个压力调节应连同一个泵位移调节。4.3 艰难的情况在实践中,最优的隧道工程,是考虑了乘客的需要,商业需求,地质条件等等。而盾构掘进机在地质条件的进展预计良好。通常情况下，在基坑开挖过程中地质调查是要进行的。然而，要知道机器通过的一切道路这是不可能的。有些意想不到的情况，如可能出现坚硬的岩石，木棍，流沙或地下河。在这项研究中，我们模拟了机器遇到硬土层这样一个严格的情景。以下展示了如何表现压力调节工作和机器。仿真结果如图10和11。注: 在仿真中时间域作为x轴。然而,时间是不实际的数据。时间设定是人工为目的的图解。在真实的隧道过程时间可能会更长时间。0-5s:这台机器是推进在软土上的正常速度，推力压力是14 MPa。5-15s:机器从软土进入硬土，因为P右不足以维持正常的速度，故右气缸速度（V右）减少。这导致剩余泵出口流量和系统压力增加。P左和左缸速度（V左）增加。系统压力增加,直到安全阀是开放的。与此同时, P左和V左降至正常水平。在20s:P右调整为31 MPa。一个脉冲发生在P左和引起脉冲在V左,和前面描述的一样。因为在正确区域的气缸会发生增加流量现象, 安全阀的流量将会减少,导致系统压力突然骤降。在25 s: V左应该减少确保直推进。然而,随着V左高于V右,非意愿右转向运动执行。手动控制是应用于P左减少直到进步。在30s:泵位移调整。压力调节后,机器现在是在一个较低的速度前进。泵位移应该减少直到过载被避免,将导致减少的推力区间压力和推进速度。40-50s:机器推进硬土。P右降低机器进入软土一点点。开始时P右相当的高,导致速度增加，而由于供油不足使得V右增加，这将导致系统压力和P右下降。 在55s:推力压力调整。推力压力可设置为14 MPa，压力调节应该发生在泵位移调整中。由于增加推力压力，推力速度发生轻微的增加。此时油供应量是不够的,但压力调节是无效的。在60s:泵位移调整。作为泵位移增加,推力压力调整到14 MPa并增加推力速度。机器以正常速度开始，当然, 方向前进比最初的角度是有变化的。仿真是指整个调整系统如何运行。角控制是关键,角反馈和转向控制也可以应用。调整通常发生后不久就去同步化。但在仿真中,调整发生当机时是“完全”推进到硬地层。其目的是找出发生在整个遭遇,换句话说,找出潜在系统的问题。5 结论本文研究盾构机压力调节的推力系统。压力调节包括两部分:压力设定的推力缸和泵位移调整。1)压力调节的一个气缸组可能会影响其他群体的压力。增加一个特定的压力和泵出口流量可能会导致小压力增加到其他群体中。在隧道开挖时小改变压力是可以接受的。2)泵位移调整时应该采取压力调节。如果泵出口流量超过了系统需求,压力调节也将实现泵压力过载虽然不必要的。如果泵出口流量小于系统需求, 虽然压力设定信号给出但压力调节是无效的。压力调节将实现泵位移增加。3) 推进速度的下降可能是遇到硬土的标志。相比之下，推进压力的下降可能是遇到软土的标志。开挖过程中，压力是第一，然后通过压力调节调整泵位移。致谢这项工作是由中国国家重点基础研究发展计划（973计划）（批准号：2007CB714000）和中国国家高技术研究发展计划（863计划）（批准号：2008AA042803）支持的。作者还要感谢西子联合控股公司和宏润建设集团的工程师对他们的帮助。参考文献1.杉本,斯顿 . 在开挖盾行为的理论模型。I:理论。第四届大地工程岩土&杂志,2002(2):138 - 1552.斯顿 ,周川在开挖盾行为的理论模型。二:应用程序。第四届大地工程岩土&杂志,2002(2):155 - 1653.玛雅,罗德里格斯.离散数值模型分析隧道开挖的土压力平衡。第四届大地工程岩土&杂志,2005(10):1234 - 12424.徐问,朱镕基,傅辽,模型试验研究隧道开挖地层适应性与EPB盾构机在沙质地层。中国岩石力学与工程,2006,25(增刊。1):2902 - 2909(中文)5.胡G,龚G,杨h .推力液压系统的盾隧道掘进机与压力和流量复合控制。中国机械工程,2006年,42(6):124 - 127(中文)6.张H,吴X,曾庆红w .研究实验和数学模型的隧道EPB盾构机,中国岩石力学与工程,2005,24(增刊。2):5762 - 57667.凌J . 在广州的地铁盾构机施工技术及其应用。广重技术,2000年,3:25 32(中文)RESEARCH ARTICLEZhibin LIU, Haibo XIE, Huayong YANGSimulation analysis of pressure regulation of hydraulic thrustsystem on a shield tunneling machine Higher Education Press and Springer-Verlag Berlin Heidelberg 2011AbstractHydraulic thrust system is an important systemin a shield tunneling machine. Pressure regulation of thrustcylinders is the most important function for thrust systemduring tunnel excavation. In this paper, a hydraulic thrustsystem is explained, and a corresponding simulation modelis carried out in order to study the system characteristics.Pressure regulation of a certain groups cylinders has littleinfluence on regulation of the other groups cylinders. Theinfluence will not affect the process much during tunnelexcavation. Pump displacement may have a greater effecton pressure regulation and oil supply flow rate should beadaptive to the systems demand. A exacting situation issimulated to explain how pressure regulation works duringtunnel excavation.Keywordstunnel, hydraulic thrust system, pressureregulation, simulation1IntroductionA shield tunnel machine is a large and complex machineused in underground tunnel excavation. It is used inconstruction projects such as underground rail lines, urbanpipelines, submarine tunnels, and so on. Hydraulictechnique is widely applied in a shield tunneling machine.For instance, it is used in the thrust system, the cutter headdrive system, the screw conveyor, and the segment erector.Research works about tunnel excavation have beencarried out. Sugimoto and Sramoon built a theoreticalmodel for tunnel excavation based on mechanics analysis1; their simulation results are in good agreement withobserved data 2. Maynar and Rodriguez used a discretenumerical model to analyze the excavation process. Somestudies about thrust force and torque were also carried out3. Xu et al. have discovered some relationship betweenworking parameters during tunnel excavation 4. Only afew studies about the hydraulic system on the machinehave been done. Hu et al. have done some work on a thrustsystem of a machine. Pressure and flow compound controlhave also been researched 5.A different system in Ref. 5 is studied in this research.Pressure regulation of thrust system is studied by using asimplified simulation model and cases of such regulationare discussed.2Thrust systemA thrust system is an important part of a shield tunnelingmachine. The system consists of power units (electricmotor and hydraulic pump), hydraulic valves, andhydraulic cylinders as actuators. The number of thrusthydraulic cylinders is usually 16 or 32. If individualcontrol of hydraulic cylinders is applied, a high number ofproportional control valves and pressure sensors arerequired. Moreover, the machine operator has to control16 or 32 pressure parameters during excavation. Individualcontrol is rather complicated and expensive. Nowadays,thrust cylindersare usually dividedintofour or five groups,with the four-group arrangement more common. Four-group cylinders are divided into Group A, Group B, GroupC, and Group D, corresponding to right zone, lower zone,left zone and upper zone. The proportion of ABCD isusually 4543, as shown in Fig. 1.More cylinders are required in Group B so as to counterthe weight of cutter head and the higher earth pressure inthe lower zone. Oil pressures in different cylinders are thesame if they are in the same group. In this case, only fourproportional control valves are required, and the machineoperator only has to control four pressure parameters.During tunnel excavation, hydraulic cylinders are suppliedwith high-pressure hydraulic oil, which exerts on thesegments to generate a thrust force to push the machineReceived January 28, 2011; accepted June 10, 2011Zhibin LIU, Haibo XIE (), Huayong YANGState Key Laboratory of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, ChinaE-mail: Front. Mech. Eng. 2011, 6(3): 377382DOI 10.1007/s11465-011-0226-yforward. The machine operator may adjust hydraulicpressures of thrust cylinders to achieve steering controland machine posture adjustment. After a thrust process isover, segments will be installed to compose a new ring oftunnel. Meanwhile, thrust cylindersare retracted in order tomake room for those segments. When a segment is located,corresponding cylinders are extended out. These cylindersexert on the segment, supporting the segment with a smallforce to complete the installation process.3Hydraulic circuit and modelingThe hydraulic circuit diagram for the thrust system isshown in Fig. 2. The system mainly consists of a variabledisplacement pump 1, a pressure relief valve 2, adirectional control valve 3, four pressure reducing valves4 and sixteen hydraulic cylinders 7. Pump displacement isproportional to the input signal. A pressure relief valvekicks into action when the system is overloaded, and adirectional control valve is used to control the extensionmotion or retraction motion of cylinders. The pressurereducing valve is the most important component and isused to adjust the hydraulic pressure of the cylinders.When the cylinder is extending, high-pressure oil comesfrom hydraulic pump 1, and then flows through directionalcontrol valve 3, pressure reducing valve 4, check valve 5,on/off valve 6, finally entering the rear chamber ofhydraulic cylinder 7. The back pressure oil flows out ofthe rod chamber of cylinder 7, then through directionalcontrol valve 3 and back into the oil tank. When thecylinder is retracting, oil flows through directional controlvalve 3, then into the rod chamber of hydraulic cylinder 7.The back pressure oil flow out of the rear chamber, thenthrough on/off valve 6, check valve 8, directional controlvalve 3, and finally into the oil tank.Commercial software AMESim is used as the analysistool for the simulation. To simplify the model, two groupsof hydraulic cylinders (typically left zone and right zone)are considered for analysis. By using these two zones, it ispossible to simulate the steering motion of the shieldmachine. The simulation model is shown as Fig. 3. All thehydraulic models are the normal models provided by thesoftware except for the pressure reducing valves. Thevalveis built as a “super-component” by compositing severalnormal models. The valve gives more details about notonly the working parameters but also the internalstructures. A variable displacement pump is applied asproportional displacement control pump as it has the samefunction as that on a working shield machine. The pumpdisplacement is proportional to the input signal.Three kinds of forces are considered in the cylinder loadmodel: earth pressure force, friction, and the force causedby the thrust motion. Earth pressure exerts on the cutterhead and linings of the machine. The pressure forceexerted on the cutter head affects the thrust motion, and thepressure force on the lining can be ignored. The frictionforce on linings of the machine caused by the earthpressure is considerable, accounting for about half or moreof the thrust force. During excavation, however, thepressure force and friction force almost maintain con-stantly. Thus, these two forces are set as constant in themodel. Earth pressure is set by the input signal of the loadmodel, and friction is set in the mass model of cylinder.There is a linear relationship between advancing speed andthrust force, as shown in Fig. 4 4. The black star dotsrepresent the experimental results for a 68% open ratiocutter head, and the white square dots represent the resultsfor 36% open ratio. Each solid line shows the linearrelationship between advancing speed and thrust force.The linear relationship has a good agreement with theobserved data in construction of Line No. 3 in theGuangzhou Metro 6.Fig. 1Arrangement of 4-group hydraulic cylindersFig. 2Hydraulic circuit of thrust system378Front. Mech. Eng. 2011, 6(3): 377382A greater thrust force causes a higher advancing speed.That is because greater force induces a greater feed rate ofcutters, and more soil will be cut off in a fixed timeinterval. The thrust force should be greater than earthpressure exerted on the cutter head together with frictionforce on the lining, in order to push the machine toadvance. If thrust force is not great enough, the machinewill not advance. In Fig. 3, there is a dead band in the loadmodel. The dead band represents the situation in whichthrust force is not great enough to push the machineforward; such a situation is referred to in Ref. 6. Whilethe machine is advancing, an increase of the thrust forcewill cause an increase of advancing speed. This experimentresult is applied to the load model. The orientation ofmachine advance is influenced by the pressure distributionof thrust cylinders so pressure regulation determines theprocession of excavation. The machine operator maycontrol the posture of the machine by adjusting thepressures of cylinder groups. The machine may steer left orright, or advance along a small angle of slope ifcorresponding settings of pressure regulation are given.Normally, at the end of a tunnel excavation, the differencebetween actual tunnel axis and designed tunnel axis shouldbe no more than 20mm. The machine operator will adjustthe machine advancing axis to agree with the designedaxis. As a result, pressure regulation is a very importantfunction during tunnel excavation.4SimulationThe simulation parameters shown in Table 1 are obtainedfrom a shield tunneling machine usedin the construction ofthe Nanjing Metro. The left and right thrust groups areused for simulation, and sixteen hydraulic cylinders arereduced to eight. A 63cc/rev maximum displacementpump should be reduced to 31.5cc/rev. Piston diameter ofa real cylinder is 300mm, and rod diameter is 240mm.Either the left or right thrust group, each of which containsfour hydraulic cylinders, is simplified to one hydrauliccylinder, which has the same work area as the originalcylinder group. As a result, the piston diameter and roddiameter of simulation cylinder are 600 and 480 mm,respectively. When oil pressure is about 8MPa, whichsupplies about 9200kN of thrust force, the machine beginsto move. Reference 7 refers that friction force accountsfor about 53.5%73% of thrust force. Accordingly, frictionforce is set at 6000kN, about 65% of thrust force. Theremaining 3200kN is exerted on the cutter head for tunnelexcavation.4.1Pressure regulationSteering control is simulated in this case. Both hydrauliccylinders are initially set to about 14MPa. The machineadvances straight and is expected to steer left. The pressureof right cylinder (Pright) should be higher than that of theleft (Pleft). Pleftmay maintain at 14MPa. Prightis set to20MPa. Simulation result is shown in Figs. 5 and 6.Prightis adjusted to 20MPa as the step signal is given.There is a small overshoot of the pressure in Fig. 5 as thereis a mass-spring system in the pilot stage. Overshoot of theFig. 3Simulation model of the thrust systemFig. 4Thrust force versus advancing speed in soft ground 4Table 1Main simulation parametersItemSetting valuePump maximum displacement30cc/revRelief pressure35.3MPaNominal pump speed1500revPiston diameter of cylinder600mmRod diameter of cylinder480mmForce exerted on cutter head3200kNFriction force6000kNZhibin LIU et al. Simulation analysis of pressure regulation of hydraulic thrust system379mass-spring system causes overshoot of the outlet pressurein the main stage. Plefthas a pulse when Prightis adjustedand increases slightly after adjustment. The sudden changein inlet pressurewill causethesame pulseinoutletpressureat first.Because the pilot stage frequency response is not highenough, when the pilot stage mechanism starts adjustingthe valves opening area, outlet pressure will decrease tothe set value. The small increase of Pleftmight be caused bythe increase of pump outlet flow rate. The pump outlet flowrate will be discussed next. This small difference inpressure will not affect the tunnel excavation. Higheradvancing speed is achieved on the right side, as shown inFig. 6. A left steering motion is carried out.4.2Pump displacement adjustmentPump displacement should be adjusted when pressureregulation is carried out. Three cases are illuminated toexplain the problem. Pressure regulation is operated as inthe previous case.Case 1: Displacement maintains at about 75% ofmaximum. The result is shown in Fig. 7.Prightis adjusted to 20MPa. Pressure regulation isachieved. However, pump outlet pressure is at 35.3MPa,which means the system is overloaded and the pressurerelief valve opens. Power loss caused by relief flow isconsiderable.Case 2: Displacement maintains at about 50% ofmaximum. The result is shown in Fig. 8.Pumpoutlet pressure issensitivetotheloadpressure.Thereis no overload during pressure regulation. However, thrustpressure cannot be adjusted to 20MPa because oil flowsupply is not enough. Higher thrust pressure causes higheradvancing speed, which means the cylinder requires more oilflow rate. Pressure regulation is invalidated in this case.Case 3: Displacement is set at 50% at first, then 75%when pressure regulationis carried out. The result is shownin Fig. 9.There is no overload. Pump outlet pressure is sensitiveto the load pressure. Thrust pressure can be adjusted to20MPa. This is because pump displacement is adaptive tothe system. A pressure regulation should be together with apump displacement regulation.4.3A tough situationIn practice, an optimal tunnel project is worked out afterconsidering commuters needs, commercial demand,geological conditions, and so on. Shield tunneling machineis expected to advance in good geological conditions.Normally, a geological survey is done before the excava-tion process. It is impossible, however, to know everythingFig. 5Pressures of right and left cylinders during pressureregulation of left steeringFig. 6Displacements of right and left cylinders during pressureregulation of left steeringFig. 7Pressures of pump outlet and right cylinder when pumpdisplacement maintains at 75% of maximum displacement380Front. Mech. Eng. 2011, 6(3): 377382in the path of the machine. Unexpected conditions such ashard rock, wooden poles, quicksand or underground rivermay present themselves. In this study, we simulate such anexacting case, with the machine encountering some hardstratum on the right side. The following shows how thepressure regulation works and how the machine behaves.The simulation result is shown in Figs. 10 and 11.Note: Time domain is used as x-axis in the simulation.However, time is not practical data. Time setting isartificial for the purpose of the illustration. Time periodmay be much longer in a real-world tunnelling process.05s: The machine is advancing straight in soft soil atnormal speed. Thrust pressure is 14MPa.515s: The machine is advancing from soft soil into hardsoil on the right side. Right cylinder speed (Vright) decreasesbecause Prightis not enough to maintain the normal speed.This causes surplus pump outlet flow rate and increase insystem pressure. Pleftand left cylinder speed (Vleft) increase.System pressure increases until relief valve is open.Meanwhile, Pleftand Vleftdrop to normal levels.At 20s: Prightis adjusted to 31MPa. A pulse occurs inPleftand causes a pulse in Vleft, as described before.Because an increase of flow rate occurs in right cylinder,flow rate of relief valve will decrease suddenly, causing asudden drop in system pressure.At 25s: Vleftshould decrease to ensure straight advance.However, as Vleftis higher than Vright, an unwanted rightsteering motion is carried out. Manual control is applied todecrease Pleftuntil the machine advances straight.At 30s: Pump displacement is adjusted. After pressureregulation, the machine is now advancing at a lower speed.Pump displacement should decrease until overload isavoided, as over-adjustment will cause decrease of thrustpressure and advancing speed.Fig. 8Pressures of pump outlet and right cylinder when pumpdisplacement maintains at 50% of maximum displacementFig. 9Pressures of pump outlet and right cylinder when pumpdisplacement is adjusted from 50% to 75% of maximumdisplacement when pressure regulation is appliedFig. 10Pressures of pump outlet, right cylinder, and left cylinderas the machine advances into and then out of some hard soilFig. 11Velocities of right cylinder and left cylinder as themachine advances into and then out of some hard soilZhibin LIU et al. Simulation analysis of pressure regulation of hydraulic thrust system3814050s: The machine is advancing out of the hard soil.Prightdecreases as the machine goes into soft soil little bylittle. Prightis rather high at the beginning, which causesspeed increases. Oil supply is not enough for the systemanymore as Vrightincreases. This causes a drop in systempressure, and Prightdecreases.At 55s: Thrust pressure is adjusted. Thrust pressure maybe set to 14MPa. Pressure regulation should take placebefore pump displacement adjustment. A slight increase ofthrust speed happens due to the increase in thrust pressure.Oil supply is not enough, however, and pressure regulationis invalidated.At 60s: Pump displacement is adjusted. As pumpdisplacement increases, thrust pressure is adjusted to14 MPa and thrust speed increases. The machine isadvancing at normal speed from now on. Of course,there is a little angle change of advancing orientationcompared to the initial angle. The simulation is to showhow the system behaves during the whole adjustment. Ifangle control is critical, angle feedback and steeringcontrol can be applied.Adjustment usually takes place shortly after desynchro-nization. But in the simulation, adjustment takes placewhen the machine is “totally” advancing into hard stratum.The purpose is to find out what happens during the wholeencounter, in other words, to find out the potential problemof the system.5ConclusionsPressure regulation of the thrust system on a shieldtunneling machine is studied in this paper. Pressureregulation includes two parts: pressure setting of thrustcylinders, and pump displacement adjustment.1) Pressure regulation of one cylinder g
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号