半挂车随动转向桥的波形压力轴承分析

选取半挂车第三轴质心和牵引座中心作为轨迹跟随研究对象,通过分析半挂汽车列车转向运动,建立牵引车前桥转角与随动桥转角的关系,基于空间摆线的波形压力轴承模型,对其进行满载应力应变分析,对随动轮的原地转向阻力矩进行分析,研究波形压力轴承低速的启锁力矩。

轴承供气压力对静压气体轴承-转子系统动力学特性影响的实验

为了研究轴承供气压力对气体轴承-转子系统动力学特性的影响,在静压气体轴承支承的压气机与透平同轴结构的涡轮膨胀制冷机试验台上,开展了相应的试验研究。采用分岔图、轴心轨迹、频谱分析等振动测试分析方法,分析了供气压力对临界转速和低频特性的影响。实验结果表明:轴承供气压力为0.80MPa,转子在26000r/min时未出现半速涡动;轴承供气压力为0.75MPa,转子在50000r/min时的低频振动幅值仅为工频振动幅值的5%,远小于相同转速时0.80MPa下的相对值(低频振动幅值与工频振动幅值的比值为34.89%)。因此,供气压力的增大带来气膜直接刚度的增加,能够消除气膜的半速涡动;供气压力的降低带来气膜阻尼比的增加,能够抑制气膜振荡的幅值。

轴承供气压力对静压气体轴承-转子系统的临界转速影响的研究

对静压气体轴承的流场模型建立、刚度计算作了分析与探讨。采用计算流体动力学(CFD)软件对气体轴承的流场进行仿真,根据仿真结果,建立基于支持向量机(SVM)的气体轴承性能模型,根据该模型计算气体轴承的刚度。在此基础上建立气体轴承-转子的有限元模型,利用有限元软件ANSYS对转子系统进行了模态分析。在考虑轴承刚度随供气压力和转速的变化下,计算转子系统的临界转速。结果表明该转子系统一、二阶临界转速对供气压力变化较为敏感,三阶临界转速不受此影响。该结果对静压气体轴承-转子系统中通过调整供气压力,避免在工作频率范围发生共振现象的产生有实际意义。

三瓦翻转压力坝轴承设计参数对承载能力的影响

建立三瓦压力坝轴承的几何模型并求解得到油膜厚度分布。基于雷诺方程建立滑动轴承理论模型,采用单元流量平衡法来离散复杂轴瓦结构的Reynolds方程并用MATLAB求解,得到轴承承载力。采用载荷约束条件和模式搜索相结合的方式求解定载荷方向下的轴承静态特性,并得到载荷收敛的油膜厚度分布与压力分布。分别改变压力坝轴承结构参数,分析各参数对轴承承载能力的影响。结果表明:椭圆率和轴承长径比对轴承承载力影响较大,其他参数的影响都相对较小;随着椭圆率和轴承长径比的增加轴承承载力提高。

WINDOWS环境下轴承压装压力实时监测系统

本文介绍了ＷＩＮＤＯＷＳ环境下轴承压装压力实时监测系统的结构和原理，概述了其软件和硬件设计，同时还简述了智能测控卡的设计。

空气轴承压力与涡轮联锁保护装置

大型空气制冷低温环境模拟试验设备中的核心产冷机器采用的是空气静压轴承涡轮,工艺上要求空气轴承压力P承在运行中直稳定于O.55±0.05 MPa范围内,特别不允许低于O.4 MPa。因涡轮的工作转速高达4万转/分,如P承突然大幅度下降,高速运转中的涡轮则会有烧坏的危险。为确保涡轮的安全。

用四氮化硅制成的冲击压力气动轴承

日本住友电气公司规模化生产四氮化硅陶瓷材料获得成功,且用此陶瓷材料制成的冲击压力气动轴承已开始上市。

MT5500B矿用卡车前轮总成耐磨装置优化

为了实现MT5500B矿用卡车前轮总成中前仰角能够在大修前稳定运行,分析了前仰角损坏的原因,以及原有耐磨装置的缺点,利用新的方法和工艺重新设计制作了一种新型的耐磨装置。结果表明:新型耐磨装置完全可以将前仰角的使用周期延长到与前轮总成大修相同,减少了1次维修作业,从根本上降低了维修人员接触危险源的频率,安全效益和经济效益显著。

动静压气体轴承-柔性转子系统的动力学特性

针对高速动静压气体轴承-柔性转子系统中存在的气膜振荡现象,考虑轴承供气压力对轴系动力学特性的影响,开展了转子系统动力学特性的实验研究。采用模态实验分析的方法,得到了转子临界转速区域,为升速实验方案的制定以及气膜振荡机理的分析提供依据。采用分岔图、三维谱图、轴心轨迹等非线性振动测试与分析方法,研究了供气压力对气膜振荡特性的影响。实验结果表明,轴承供气压力对转子的升速响应和失稳门槛转速有着重要的影响。随着供气压力的增加,消除了二阶模态气膜振荡,同时,变轴承供气压力方案下1阶模态气膜振荡的幅值比0.4 MPa下1阶模态气膜振荡的幅值小。另外,较高的轴承供气压力能够提供较大的轴承直接刚度,因此,平动、锥动以及1阶弯曲固有频率随轴承供气压力的增加而增加。

供气压力对高速涡轮转子系统气膜振荡影响的试验

采用气体轴承的高速微型燃气轮机具有结构紧凑、做功功率密度大、高转速、轴承功耗低等优点。然而,由于气体轴承润滑介质气体自身的粘度小,导致了气体润滑轴承有承载能力差、摩擦系数小、高速下的稳定性差等劣势。基于气体轴承支承条件下的高速涡轮转子系统,通过试验对比研究了轴承供气压力的提高对转子系统气膜振荡的影响。试验结果表明:气膜振荡发生后,轴承供气压力的提高能够抑制甚至消除气膜振荡,从而控制了混沌运动的幅值边界,最终达到提高轴承—转子系统稳定性的目的。

选煤厂耙式浓缩机滚轮式中心旋转装置的研制

分析了铁法能源有限公司小青煤矿选煤厂原准24 m周边传动胶轮式耙式浓缩机中心柱传动方式存在的不足,阐述了对中心柱传动的改进方案及设计原理,并进行了前后效果对比分析。

某发动机滑油消耗量大故障影响因素分析

某发动机批生产中多次出现滑油消耗量大故障,其故障率较高,严重影响了发动机正常生产与交付。为了解决这一问题,对该机滑油系统结构原理特点进行了分析,找出影响滑油消耗量的主要因素,并通过对滑油系统(供、回油系统、空气密封系统)各参数的大量统计分析、计算、试验研究,找出其对滑油消耗量的影响及相互关系,制定出滑油消耗量大故障排故措施,并在生产中应用,取得了良好效果。

半自磨系统主要控制参数研究

通过对某矿山半自磨系统各控制参数关系的研究和分析,发现半自磨系统主要控制参数为功率、励磁电流、轴承压力和电耳。控制参数之间存在以下关系:功率随励磁电流、轴承压力增加而增大,随着电耳增加而减小,但各参数之间无线性关系。为了更好地实现半自磨系统控制,需进一步结合生产中其他条件建立完整的数学模型。

Improved finite difference method for pressure distribution of aerostatic bearing

An improved finite difference method （FDM）is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aerostatic bearings. A detailed theoretical analysis of the pressure distribution of the orifice-compensated aerostatic journal bearing is presented. The nonlinear dimensionless Reynolds equation of the aerostatic journal bearing is solved by the finite difference method. Based on the principle of flow equilibrium, a new iterative algorithm named the variable step size successive approximation method is presented to adjust the pressure at the orifice in the iterative process and enhance the efficiency and convergence performance of the algorithm. A general program is developed to analyze the pressure distribution of the aerostatic journal bearing by Matlab tool. The results show that the improved finite difference method is highly effective, reliable, stable, and convergent. Even when very thin gas film thicknesses （less than 2 Win）are considered, the improved calculation method still yields a result and converges fast.

Entrance Effect on Load Capacity of Orifice Compensated Aerostatic Bearing with Feeding Pocket

The current research of the aerostatic thrust bearing mainly focuses on the porous material bearing and inherent compensated air bearing, which aims at obtaining small physical dimension and large load capacity. Although porous material bearing appears larger load capacity, materials anisotropy itself and void content distortion caused in heat-treating, and machining processes add greater complexity to internal flow transfer process. Inherent compensated air bearing has the advantages of simple structure and good stability, but its load capacity and static stiffness is not worth somewhat. In this paper, based on hydrostatic lubrication theory, finite volume method is presented for taking entrance effects into account in computing pressure distribution, load capacity and mass flow rates of circular aerostatic thrust bearings. Technical analysis, numerical simulations and laboratory demonstration tests of influence of pocket diameter and pocket depth on loading capacity of aerostatic thrust bearing are carried out on simple orifice compensated air bearings with feeding pockets. The static parameters, such as air consumption and pressure distributions, are measured as a function of supply pressure and air gap height for several different orifices and pockets size. Entrance effects are described in term of typical throttling types, and the effect of pocket diameter and pocket depth on load capacity is systematically described respectively. The proposed research results uncover the causation of throttling action of the orifice compensated air bearing with feed pocket and further develop and improve the design theory of air bearing.

Analysis of axial force of double circular arc helical gear hydraulic pump and design of its balancing device

In view of the axial force produced in the working process of double arc helical gear hydraulic pump,the theory of differential equation of curve and curved surface was utilized so that the calculation formula of axial force was obtained and the relationship between the axial force and structure parameters of gears was clarified.In order to balance the axial force,the pressure oil in the high pressure area was introduced into the end face of the plunger to press the plunger against the gear shaft,and the hydrostatic bearing whose type is plunger at the end of the shaft was designed.In order to verify the balance effect of axial force,the leakage owing to end clearance and volume efficiency of gear hydraulic pump before and after the balancing process was analyzed.This paper provides a new analysis idea and balance scheme for the axial force produced in the working process of the double arc helical gear hydraulic pump,which can reduce the leakage owing to end clearance caused by the axial force and improve the volume efficiency of the gear hydraulic pump.

Strength of circular concrete columns under concentric compression

An experimental study, in which six columns were loaded concentrically toinvestigate the behavior of reinforced normal strength and high strength circular columns underconcentric compression, is described. The concrete strengths of the columns were 30 MPa and 60 MPa.The primary variables considered were the concrete strength and the amount of transversereinforcement. Test results indicate that smaller hoop spacing provides higher column capacity andgreater strength enhancement in a confined concrete core of columns. For the same lateralconfinement, high strength concrete columns develop lower strength enhancement than normal strengthconcrete columns. Both the strength enhancement ratio (f'_(cc) /f'_(co)) and the column capacityratio (P_(test)/P_o) were observed to show linear increase variations with rho_s f_(yt)/f'_c incircular columns.

Fatigue Crack Initiation and Propagation of Aluminum Alloy Bearings

Observation of fatigue crack initiation and propagation during fatigue test in ALSn20Cu bearing has been presented. Journal center orbit, oil film pressure and stress distribution in alloy layer have been calculated and are taken as the basis for theoretically simulating the bearing fatigue process. It is found that the calculated results are in good accordance with the experimental results, which provides a feasible way for investigation of fatigue crack propagation process in the bearing.