Thrust distribution characteristics of thrust systems of shield machines based on spatial force ellipse model in mixed ground

The objective of this research is to investigate force distribution characteristics for propelling system of tunneling machines in mixed ground. First, a mechanical model for pushing system in composite strata is constructed. Then, eccentricity trunk is determined using spatial force ellipse eccentricity to measure the degree of uniformity of forces applied on rear segments in a thrust system. Finally, the eccentricity trunk is used to the thrust system of a tunneling machine applied in engineering. Force distribution performance of various arrangements with equal quantities of jacks is discussed in detail. Results from virtual prototype simulation prove the numerical analytical results. A theoretical foundation and support is provided for the design of non-equidistant pushing system of tunneling machines under composite stratum.     

盾构机推进液压系统比例压力流量复合控制仿真

本文以盾构挖掘机为背景,对其推进负载进行简化,建立盾构推进系统的模型,并进行仿真分析.提出比例压力流量复合控制方案,并应用AMEsim对其进行仿真.仿真证明比例压力流量复合控制方式可以减小控制压力引起的流量波动,提高了系统的控制性能,对盾构的自动控制有重要意义.     

Simulation analysis of pressure regulation of hydraulic thrust system on a shield tunneling machine

Hydraulic thrust system is an important system in a shield tunneling machine. Pressure regulation of thrust cylinders is the most important function for thrust system during tunnel excavation. In this paper, a hydraulic thrust system is explained, and a corresponding simulation model is carried out in order to study the system characteristics. Pressure regulation of a certain group’s cylinders has little influence on regulation of the other groups’ cylinders. The influence will not affect the process much during tunnel excavation. Pump displacement may have a greater effect on pressure regulation and oil supply flow rate should be adaptive to the system’s demand. A exacting situation is simulated to explain how pressure regulation works during tunnel excavation.     

高速微孔钻床主轴系统的动态特性分析

依据转子动力学理论,利用Timoshenko粱轴理论,建立了包含旋转惯性力、陀螺力矩、离心力、弯曲变形、扭转变形、钻削轴向力和钻头的三种边界条件在内的高速微孔钻床主轴系统动力学模型。在利用实验和现有文献对所建立的模型进行了检验的基础上,对高速微孔钻床主轴系统的临界转速、临界轴向压力进行了分析。结果表明高速微孔钻床主轴系统的临界转速随钻削轴向压力的增大而减小,并且钻削过程中比刚入钻时能承受更高的转速,更大的轴向力;临界轴向压力随高速微孔钻床主轴系统转速的升高而降低,即随着钻削转速的提高,应适当减小钻削轴向力。     

冗余驱动盾构机推进系统机液耦合模型及载荷特性分析

针对某型盾构机推进系统分别建立了考虑冗余驱动的机械系统动力学模型和单组液压系统的简化液压模型,在此基础上建立了盾构机整个推进系统的机液耦合模型,给出基于外载-减压阀阀口开度关系的系统状态判定方法。在MATLAB/Simulink环境下进行数值建模与仿真,分析极端工况下各组推进缸的载荷特性。结果表明,该方法能够有效评价推进系统状态,并可为盾构机异质岩土掘进时驱动力分配的控制提供依据。     

Research on thermal deformation of large-scale computer numerical control gear hobbing machines

Research on thermal deformation of large-scale computer numerical control (CNC) hobbing machines is on the purpose of obtaining the law of thermal deformation of gear hobbing machines to improve machining precision. According to the structure characteristics of hobbing machines, this paper presents a novel computing model of thermal deformation based on the theory of the thermal expansion deformation of metallic materials, the extensional beam theory, non-uniform temperature distribution of the Euler-Bernoulli beam and Kirchhoff theory of plane-section assumption. Then, the coupling theory of axial and bending deformation of hobbing machines based on the deformation element and equilibrium element method is proposed. The experimental measurement system and platform for thermal deformation of gear hobbing machines is established. The temperature and displacement data of thermal deformation of a certain type gear hobbing machine is analyzed, which has demonstrated the law of thermal deformation of hobbing machines. The locus curves for overall displacement error of cutting points and teeth trace error are obtained. Comparing deformation theory and experimental data, the relative error is lower than 5%, which verifies the computing model proposed by this paper, and shows the research method has great significance for structural optimization, local temperature control, and prediction and compensation for thermal deformation error of gear hobbing machines.     

止推滑动轴承的温度场和热变形分析

通过对止推滑动轴承的传热学、摩擦学研究，建立了该轴承相应的稳态温度场和热变形的三维热分析有限元模型，并运用ANSYS分析了轴承处于热平衡状态时的温升和热变形。研究结果表明，对于井下用止推滑动轴承，由于其摩擦产生的热量很大，在地面常温下设计时应考虑到热变形对轴承间隙的影响。     

Thrust and Torque Characteristics Based on a New cutter-head Load Model

Full face rock tunnel boring machine(TBM) has been widely used in hard rock tunnels, however, there are few published theory about cutter-head design, and the design criteria of cutter-head under compl...     

土压平衡盾构地层适应性设计理论和方法研究

为了探讨盾构机工作参数与土体的相互关系,针对土压平衡盾构的特点在模拟试验台上进行了掘进试验。分析了盾构总推力、刀盘扭矩和土仓土压力的变化关系及其影响因素,同时还研究了刀盘开口率对刀盘扭矩的影响规律。试验结果表明：在土压平衡的情况下,刀盘扭矩和盾构总推力有良好的线性关系,并且盾构总推力随着推进距离的增加而缓慢地增加。     

基于力学分析的TBM掘进总推力预测模型研究*

提出一种基于力学分析的全断面岩石隧道掘进机(Tunnel boring machine,TBM)掘进装备总推力的预测建模方法。在TBM装备掘进过程中,总推力的影响因素多且复杂,主要包括施工地质条件、装备结构特征、装备掘进状态等几类核心参量。从分析装备与地质间相互作用的力学特征入手,通过求解滚刀与岩石接触弧线上岩石单元体的极限应力状态,建立能反映地质、操作等关键参量影响的刀盘破岩力计算表达式。在刀盘载荷分析基础上,补充考虑装备护盾、后续设备等部件上作用的载荷分量,建立TBM装备掘进总推力预测模型,并结合我国两个典型工程案例对所建模型进行分析与验证。进一步引入单位贯入度对应总推力值,作为讨论TBM载荷地质适应性的指标,近似剥离操作参数的影响,分析载荷与地质参数间的内在相关关系。分析结果表明,在各个地质参数中,单轴抗压强度是对掘进总推力起到核心影响的关键地质参数,与单位贯入度对应的总推力间存在近似的线性关系。本工作可对不同地质条件与不同操作状态下,TBM装备掘进总推力进行预估计算,为装备载荷的优化设计与智能控制提供参考依据。     

刚性和弹性支撑可倾瓦推力轴承稳态特性分析

建立刚性球头支撑和弹性橡胶垫支撑可倾瓦推力轴承热弹流耦合模型；在弹性橡胶垫支撑可倾瓦推力轴承橡胶垫的弹性变形分析中采用了变形协调矩阵方法，以协调匹配橡胶垫变形和水膜厚度分布，同时在搜索稳态解的过程中引入模拟退火算法；基于变分原理求解Reynolds方程，得到了轴承水膜压力分布，并比较2种推力轴承在转子存在角不对中时的静特性。结果表明：理想工况下，刚、弹支可倾瓦推力轴承稳态特性没有明显区别；当转子存在不对中时，刚性球头支撑可倾瓦轴承在不同瓦块之间受力偏载严重，进而导致瓦面最小水膜厚度过小，瓦块容易出现磨损，而弹性支撑瓦不同瓦块之间水膜力分布更均匀，利于轴承的长期可靠运行。     

盾构机推进液压系统设计与仿真分析

对盾构机推进液压系统做了详细的介绍,阐述了其系统组成及工作原理。该系统应用电液比例控制技术实现了推进力和位移的控制。通过对推进系统的仿真分析表明:采用电液比例泵和比例减压阀的控制策略,满足了系统的推进速度和压力要求。     

推力瓦热瞬态变形机理及抑制方法研究

针对核主泵水润滑推力轴承在事故工况下的热瞬态过程,建立了热固耦合瞬态有限元分析模型。基于所建立模型,分析了常见两层和三层结构推力瓦热瞬态过程瓦面变形,重点分析了三层结构推力瓦隔热层厚度对瓦面变形的影响。随后,进一步探索了遏制瓦面凹变形的方法,阐明了热瞬态过程中瓦面温度场分布不均是产生瓦面凹变形的主因。进一步提出一种新型包边式推力瓦,并仿真验证其能够有效降低热瞬态过程瓦面凹变形,为核主泵水润滑推力轴承的推力瓦设计提供了新思路。     

一种流体驱动式模块化软体仿生象鼻关节变刚度结构设计及仿真分析

在兼顾软体抓持装置顺应性的前提下,为进一步提升其承载能力,提出一种采用磁流变液变刚度控制的流体驱动式模块化软体仿生象鼻机构。建立了仿生象鼻关节变形量和刚度理论数学模型;利用有限元分析方法基于Yeoh模型对不同结构参数的仿生象鼻关节进行了变形仿真分析,在相同压力下优选出了变形量最大的模型结构和确定了最佳输入气体压力值;对关节变形后两端电磁铁的叠加磁场分布进行了有限元仿真,通过分析磁场分布均匀性初步确定了两端电磁铁形成磁场的最佳距离即关节长度;最后对不同长度关节进行了变形仿真分析,综合考虑磁场分布均匀性和变形量,通过两者的最优组合确定最终关节长度,验证了仿生象鼻的多自由度变形和可变刚度特性。     

Investigation of tribological behaviors of annular rings with spiral groove

A series of experiments is conducted to study the tribological behavior of spiral groove thrust bearings. The experimental system consists of a nominally flat upper ring mating with a stationary spiral groove lower ring in fully flooded lubrication environment. Spiral groove thrust bearings with different spiral angles subjected to different loads and speeds are tested. Stribeck-like curves are obtained and their characteristics are discussed. Transition points from mixed to hydrodynamic lubrication are experimentally established. In addition, a theoretical model is developed to gain further insight into the frictional characteristics of spiral grooves in both the hydrodynamic regime and the mixed lubrication regime.     

Investigation of tribological behaviors of annular rings with spiral groove

A series of experiments is conducted to study the tribological behavior of spiral groove thrust bearings. The experimental system consists of a nominally flat upper ring mating with a stationary spiral groove lower ring in fully flooded lubrication environment. Spiral groove thrust bearings with different spiral angles subjected to different loads and speeds are tested. Stribeck-like curves are obtained and their characteristics are discussed. Transition points from mixed to hydrodynamic lubrication are experimentally established. In addition, a theoretical model is developed to gain further insight into the frictional characteristics of spiral grooves in both the hydrodynamic regime and the mixed lubrication regime.     

变转速电液推进机构

电液推进机构用于大型构件的移位装船作业,由夹紧模块夹持钢轨以提供反力支撑,通过推进液压缸完成构件的移位。电液推进机构采用变转速泵控方式,微控制器发出脉宽调制控制信号,作为变频器的输入指令信号,改变定量液压泵驱动电机的转速,以调节定量液压泵的输出流量,进而控制构件的移位速度。工程应用表明变转速电液推进机构具有效率高、响应快等特点,能够满足构件移位的作业需求。     

Analysis of a hydrodynamic thrust bearing with elastic deformation using a recurrent neural network

A theoretical analysis on the general behaviour of a thrust bearing is presented in this paper. The model programme using a method adaptation of finite differences was developed to solve the Reynolds equation for lubrication. The model in the theoretical analysis uses a single one-dimensional grid. The altering of total lubrication load obtained in the result of under-cutting in the thrust bearing have been determined together with the parameters such as oil film thickness and pressure. Parameters such as the pressure and thickness of the oil film were determined. The hydrodynamic behaviour of thrust bearing was analysed by considering of different dimensionless system pressure, speed and geometry of the bearing. The effect of the elastic load due to elastic deflection is taken into account as on the load-bearing characteristics is included. Also, a proposed neural network predictor is utilised to analyse of the general behaviour of thrust bearing. The results of the proposed neural network predictor gives superior performance for analysing of the behaviour of a thrust bearing undergoing in elastic deformation.     

轴—壳体系统耦合振动控制原理分析及试验

螺旋桨脉动力是引起轴系—壳体振动的主要因素。基于频域模型,研究轴—壳系统耦合振动特性及参数影响,从原理上分析在推进轴系上施加控制力来抑制耦合系统振动的控制方法,并讨论基于自适应前馈控制策略的主动控制方案。采用自适应对消及归一化最小均方算法,在轴上施加纵向控制力,实时抵消脉动推力,降低轴系纵向振动,由此抑制由于轴系振动所引起的壳体振动。仿真结果表明：控制力施加位置对控制效果影响很小,不同轴承刚度对控制力大小的需求不同,刚度较小时误差收敛速度较慢,刚度达到一定程度以后收敛速度不变。通过轴—壳体试验系统对原理分析进行验证,结果也表明推力轴承刚度对轴系纵振频率的影响,所提出的控制方法能够有效地抑制壳体振动。     

Calculation of six-lobe and eight-lobe deformable thrust sliding bearings

The paper deals with the development of a model and the calculation of characteristics of a hydrodynamic thrust sliding bearing which provides the compensation of the axial force in high-speed and low-speed rotors of stationary gas turbine units. In the framework of creating a method for determining the stiffness and damping characteristics of the bearing and calculating the parameters of lubricant flow in the gap, we develop a model of the thrust bearing based on the coupled solution of the problem of the flow of incompressible lubricant between the sliding surfaces and the problem of the deformation of the bearing parts and the shaft under the lubricant pressure. The model makes it possible to find the basic characteristics of the thrust sliding bearing at various relative displacements of the bearing and shaft. The bearing model is verified by comparing our results with the results of calculating lubricant flow in the STAR-CD software package and the results of calculations and experiments reported in the literature. The stiffness and damping characteristics are calculated for two thrust sliding bearings with six and eight lobes, depending on the sliding surfaces closure and variations in the shaft rotation angle with account of the deformation of the sliding surfaces. A significant influence of the shaft rotation angles in the bearing section and the deformations of the sliding surfaces on the integral characteristics of the bearing is demonstrated.