齿轮电蚀失效分析

对齿轮电蚀失效进行了详细的分析;论述了齿轮电蚀的特性以及电蚀表面的宏（微）观相貌特征;简要阐明了齿轮电蚀失效的机理。     

Experimental measurement of strain and stress state at the contacting helical gear pairs

Contact stress evaluation in gears has been a complex area of research, due to its non-linear and non-uniform nature of stress distribution. The high contact stress on gears results in pitting and scuffing, which leads to tooth failure. Furthermore the effects of friction on gear contacts make the problem more complicated. Hence, in this paper, attempt has been made to study contact stress in gears. The experimental testing and analysis of the helical gear was carried out using Gear Dynamic Stress Test Rig (GDSTR). GDSTR is a newly designed test rig to compute the contact stresses on the gear pair contact, under real gear conditions. GDSTR uses the strain gauge and carbon slip rings to measure the surface contact stresses at the contacting points of a meshed gears. The experimental analysis showed promising results which have been verified by the finite element frictional contact analysis. The experimental testing was carried out on 5° and 25° helical gear pairs. Helical gear models with the same specifications and for different frictional coefficient conditions were also generated using FE modelling. The frictional contact stress analysis using FEM has been used for comparison with the experimental results.     

A new approach for polymer composite gear design

A new design method for polymer composite gear has been proposed in the current paper. This design method is based on the link between polymer gear wear rate and its surface temperature. It has been found from the tests that the polymer (acetal) gear wear rate will be increased dramatically when the load reaches a critical value for a specific geometry. The gear surface will wear slowly with a low specific wear rate if the gear is loaded below the critical one. The possible reason of the sudden increase in wear rate is due to the gear operating temperature reaching the material melting point under the critical load condition. Gear surface temperature has been then investigated in detail through three components: ambient, bulk and flash temperatures. Through extensive experimental investigations and modelling on gear surface temperature variations, a general relation has been built up between gear surface temperature and gear load capacity. The method has been related to test results under different operating ambient temperature and gear geometries. Good agreement has been achieved between the proposed method predictions and experimental test results. Experimental investigation on polymer composite (glass fibre reinforced nylon with PTFE as internal lubricant) gears have also been carried out and two forms of failure have been found, root and pitch fractures.     

搅拌机减速箱国产化改进与性能提升

对原进口搅拌机减速箱输出轴上圆柱齿轮齿面点蚀、齿面磨损、轮齿折断等现象的失效原因分析及理论计算,在齿轮材料、加工工艺、结构优化设计等方面提出改进措施,并进行相关失效零部件及箱体国产化制造,实际使用证实了良好的经济效果。     

蜗杆传动的润滑分析

通过对蜗杆传动的润滑、效率与表面微峰接触载荷的分析,提出了一个新的蜗杆传动胶合失效判断因子,它综合考虑了润滑油膜破裂、微峰塑性变形与摩擦发热三种因素;基于Chittenden等的油膜厚度公式分析了蜗杆传动的油膜厚度,理论计算结果表明这一新的胶合因子在蜗杆传动润滑分析中具有指导意义,但对新的胶合因子仍需进一步实验验证。     

冷却塔风机齿轮失效的弹性流体润滑分析

针对大型冷却塔风机的减速器齿轮失效情况,在校核了圆柱和圆锥齿轮的设计强度的基础上,应用弹性流体润滑的理论,根据可压缩流Reynolds方程所建立的膜厚公式,计算出齿面润滑油膜厚度,并据此研究了工作中的齿轮润滑状况和齿面损伤机理,确定齿轮过早失效的主要原因不是由于齿轮的设计强度不足,而主要是无法在齿面间形成有效油膜,齿轮工作中两齿面有直接接触现象造成,分析出失效的原因是齿轮的润滑不良。并提出相应的解决办法和改进建议,可作为齿轮传动设计和故障分析的参考依据。     

Multisensor monitoring of gear tooth fatigue for predictive diagnostics

Successful machinery diagnostics depends on the collection and processing of prognostic features that relate back to failure precursors. Since gear teeth are a critical element in drive-train systems, single gear tooth failure has been examined, and the identification of new prognostic features explored. A special jig was employed to orient and constrain gear samples while Hertzian loading was applied along a single contact line on the gear tooth face. This set-up simulates the loading conditions experienced by a single tooth during gear train operation. Optical, ultrasonic, and mechanical sensors measured a variety of observables while the gear fatigue testing was under way. After monitoring the fatigue test with these three non-commensurate sensors, data features were related to crack growth phenomena. Data collection, analysis, and interpretation are discussed for spur gear samples that show both the absence and presence of cracks and support the validity of the identified features as failure precursors. The results demonstrate the potential for using non-traditional sensors and techniques for an in situ monitoring system.     

Performance studies on salt bath treated low-carbon steel gears

Tufftride TF1 treated low-carbon steel gears were tested in a back-to-back gear test rig. The purpose was to generate design data and to obtain information on the mechanism of failure. Contact stress versus cycles to failure (S-N) curve has been plotted, and the results correlated with data obtained from rolling contact fatigue tests. In an attempt to obtain a clear understanding of events at the contact surfaces of gear teeth, a complete analysis of gear operating conditions was made and the results are presented. Failure investigations have been performed using optical and scanning electron microscopes     

Polymer gear surface thermal wear and its performance prediction

This paper will concentrate on acetal gear wear behaviour and its performance prediction based on the extensive investigations on the gear thermal mechanical contact both experimentally and numerically. It has been found from the tests that acetal gear wear rate will be increased dramatically when the load reaches a critical value for a specific geometry and running speed. The gear surface will wear slowly with a low specific wear rate if the gear is loaded below the critical one. The possible reason of the sudden increase in wear rate is due to the gear operating temperature reaching the material melting point under the critical load condition. Gear surface temperature has been then investigated in details through three components: ambient, bulk and flash temperatures. Through extensive experimental investigations and modelling on gear surface temperature variations, a general relation has been built up between gear surface temperature and gear load capacity. An approach for acetal gear transition torque prediction has been proposed and this method is based on the link between polymer gear wear rate and its surface temperature. The method has been related to test results under different operating speeds and gear geometries. Good agreements have been achieved between the proposed method predictions and experimental test results.     

齿轮泵结合面漏油问题的解决

该文对高压齿轮泵的常见故障分析,多次对比改进,找到了发生结合面渗漏的根本原因,并提出改进方案,在实践中见到成效。此故障的改进对现有齿轮泵的设计和维修具有指导意义。     

基于高阶谱的齿轮故障特征提取方法研究

基于高阶谱能够抑制高斯信号,并且可以在较强的背景噪声中提取故障信息的特点,在分析高阶谱的理论基础上,针对齿轮振动信号的非线性、频谱成分多样性等特点,研究了基于高阶谱分析的机械故障特征提取方法,提出了基于双谱估计的齿轮故障诊断方法.试验结果表明,该方法能够有效地将正常及不同裂纹程度的齿轮区分开来.     

利用小波包络诊断齿轮故障

根据小波能对信号包络提取的原理,对齿轮箱的振动信号进行了研究,应用基于小波原理的自信息包络提取法,同时,把该方法应用于分析齿轮故障,证明该方法能更有效地提取信号包络,适用于分析齿轮故障。     

Effect of sursulf treatment on the performance of 0.14% C steel gears

Sursulf-treated low carbon steel gears were tested in a back-to-back gear test rig. The failure of the gears is by pitting and the contact stress-pitting life curve has been established. Wear particle analysis of the lubricating oil was carried out to analyse the nature of the failure. The study reveals that Sursulf treatment on low carbon steel gears considerably improves their performance. The cumulative wear particle concentration at the pitting limit has been suggested as a basis for predicting the onset of failure of the gears.     

On the prediction of the design criteria for modification of contact stresses due to thermal stresses in the gear mesh

The mechanism of surface failure due to temperature rise is a very important problem in gear design. Thermal considerations have received considerable attention from the gear researchers but only for scoring failures when the destruction of lubrication film occurs as a result of temperature rise. In spite of the wealth of literature on this subject, this problem is not fully analyzed.The objectives of this paper are to consider the mechanisms of thermal stresses and the thermal cycling in contact zone, during the gear mesh. This research has been conducted for the first point of contact based on consideration of transient heat transfer, elastohydrodynamic lubrications, and surface roughness and gear material.A procedure presented in this paper evaluating the stresses (thermal and mechanical) and predicting the design criteria for modifying the contact stresses due to thermal stresses. The effect of the material, oil film thickness, surface roughness and geometric operating parameters on modification parameter is illustrated. Also the effects of a load on the temperature rise and the modification parameters are evaluated.     

Acetal gear wear and performance prediction under unlubricated running condition

Tests have shown that the acetal gear wear rate will be increased dramatically when the load reaches a critical value for a specific geometry. The gear surface will wear slowly with a low specific wear rate if the gear is loaded below the critical condition. The sudden increase in wear rate may be due to the gear operating temperature reaching the material melting point under the critical load condition. Gear surface temperature has been investigated in detail by studying three components: ambient, bulk and flash temperatures. Through extensive experimental investigations and modelling on gear surface temperature variations, a general relation has been built up between gear surface temperature and gear load capacity. A new design method for acetal gear has been proposed based on the link between polymer gear wear rate and its surface temperature. The method has been related to test results under different operating ambient temperature and gear geometries. Good agreements have been achieved between the proposed method predictions and experimental test results. The maximum torque the acetal gears can transmit is 9 Nm for both the driver and driven with a 2 mm module, 30 teeth and 17 mm face width. Copyright © 2006 John Wiley & Sons, Ltd.     

基于总成的重型汽车变速箱齿轮弯曲应力分析

以建立重型汽车变速箱总'成为基础,论述一挡齿轮总成条件下有限元网格的划分及网格密度的确定,对一倍额定动态转矩下的中间轴常啮合齿轮表面接触压力、接触线的状态、齿根弯曲应力进行了深入的分析.实验测试结果和有限元分析结果的对比分析表明,因充分考虑了总成条件下啮合齿轮接触等问题对齿轮强度的影响,使分析和测试的齿根弯曲应力趋势保持一致,强度相对误差范围在±20%以内.     

对数螺旋锥齿轮建模优化与加工检测

为了提高对数螺旋锥齿轮三维精确模型的精确性和准确性,提出了基于MATLAB和Pro/E的对数螺旋锥齿轮离散化建模方法。首先,根据对数锥齿轮的形成原理建立齿面方程;然后,根据齿轮的具体参数计算齿面边界条件;接着利用MATLAB计算出齿面离散坐标点,将这些坐标点导入到三维建模软件Pro/E中,利用其逆向工程模块建立齿面的离散模型。以Pro/E为二次开发平台,运用C语言编程建立只需要输入相应参数即可自动完成锥齿轮创建的程序,为后续锥齿轮的静力学分析、动力学分析和齿面修形奠定了基础。     

润滑和载荷状态对聚甲醛齿轮服役性能的影响

基于齿轮耐久性能试验台开展了一系列干接触/油润滑下POM(聚甲醛)-POM齿轮副承载能力试验,并测量了服役过程中的轮齿温度、磨损量、齿廓精度和齿面形貌。试验发现,POM齿轮失效形式与载荷和润滑方式有关。通过对齿面微观形貌和磨屑表征,确认干接触下POM齿轮主要磨损模式为黏着磨损与磨粒磨损,而油润滑下POM齿轮失效形式为接触疲劳失效。由于润滑油减少了齿面摩擦,降低了运行温度,延缓了齿面劣化程度,因此POM齿轮在油润滑下的承载能力明显提高。     

点蚀故障对齿轮传动系统噪声的影响

针对不同数滚机床齿轮齿面点蚀故障严重程度对齿轮传动系统噪声的影响,基于赫兹理论力学模型,运用ABAQUS创建了齿轮副的应力仿真分析模型,求解在未点蚀及不同点蚀故障严重程度下齿面最大接触应力,并对比了传动扭矩对不同点蚀故模型最大接触应力的影响。开展了不同齿面点蚀故障齿轮模拟工况下的噪声测试实验,通过对比齿轮副试样噪声的敏感性分析不同点蚀故障严重程度的影响。有限元结果表明,传动扭矩与齿面最大接触应力呈线性关系,点蚀故障越严重,齿面点蚀区域接触冲击应力越大;齿轮故障噪声测试实验研究结果则表明,基于微点蚀、点蚀失效形式之间存在的竞争机制,点蚀故障越严重,对应的噪声曲线峰值越大;随着齿轮负载、转速的增大,点蚀故障齿轮噪声也逐渐增大。     

大功率风力发电机增速齿轮断裂原因分析

通过断口宏微观形貌观察、化学成分分析、显微组织观察以及硬度测试等方法,系统分析了某大功率风力发电机增速齿轮断裂的原因。结果表明:轮齿外表面存在密集分布的点蚀坑及微孔缺陷,是裂纹源;在较高水平的冲击与弯曲载荷共同作用下使微裂纹扩展,从而最终导致齿轮疲劳断裂。