A New Roughness Parameter Including Hardness and Contact Frequency Effects on Lubricated Rolling/Sliding Wear

Surface roughness, roughness arrangement, film thickness, material hardness, and run-in process have significant effects on the lubricated rolling/sliding wear of mechanical components such as gears and bearings. In conventional analysis, a film thickness parameter is calculated by a geometric approach to study the wear resistance of a contact system without considering the effects of material hardness and run-in process. Although the conventional parameter is simple, it does not correlate with some experimental observations. In this work, a new roughness parameter is developed for the prediction of lubricated rolling/sliding wear. Surface roughness will be adjusted by its hardness and contact frequency. The calculation results are consistent with four groups of experimental data. It is proved that the conventional models can be derived as a special case of the new model when two contact surfaces have the same properties. The new model can be used in the optimal design and manufacturing of mechanical interfaces to reduce lubricated rolling/sliding wear.     

Boundary Lubrication of Steel Surfaces with Borate,Phosphorus, and Sulfur Containing Lubricants at Relatively Low and Elevated Temperatures

Prolonging the life of engineering components through lubricant formulation to achieve better wear resistance and higher oxidation stability is of paramount importance to many mechanical systems, such as automotive gears and bearings. This can be accomplished with formulated lubricants that limit the generation of wear debris causing severe abrasion and protect the contacting surfaces through the formation of wear-resistant tribofilms. In this study, a ball-on-disk tribometer was used to characterize the friction and wear properties of steel surfaces slid in the boundary lubrication regime. An experimental scheme was developed to allow the statistical screening of various lubricant formulations. Sliding experiments were performed in baths of different lubricants at relatively low and elevated temperatures, approximately 32 and 100°C, respectively, under conditions of constant load and sliding speed. Surface profilometry, optical microscopy, and scanning electron microscopy were used to characterize the dominant friction and wear mechanisms. The tribological properties were found to strongly depend on the temperature and the additives (e.g., borate, phosphorus, and sulfur) present in the blended lubricants. The superior high-temperature wear performance of the lubricant with the higher borate content is indicative of the formation of a durable tribofilm that reduces metal-to-metal adhesion, material transfer, and surface plowing by wear debris.     

Effect of sursulf treatment on fatigue life of medium carbon steel spur gears

Medium carbon steel gears untreated as well as Sursulf treated were tested in a back-to-back gear test rig. The failure of the test gears was by pitting. The contact stress-pitting life curves have been established for both untreated and Sursulf treated conditions. Sursulf treated gears exhibited low wear compared to untreated. Wear particle analysis of lubricating oil was carried out to analyse the nature of failure. Cumulative wear particle concentration at pitting limit has been suggested as a basis for predicting the onset of the failure in the gears.     

激光淬火齿轮的疲劳寿命和耐磨性机理分析

激光淬火齿轮的疲劳寿命试验研究结果表明，激光淬火齿轮疲劳寿命大大高于常规淬火齿轮，同时还具有很高的耐磨性、抗疲劳折断以及抗剥落性能。本文在试验研究的基础上，分析了激光淬火齿轮具有高疲劳寿命和耐磨性的机理，以及激光淬火齿轮疲劳寿命大大高于常规淬火的原因。     

转叶式舵机密封件在不同磨粒尺寸下的摩擦学特征研究

船舶转叶式舵机因体积小、功率密度高而逐渐替代传统的柱塞式舵机.然而,磨损过程中产生的磨粒常使叶片密封件产生异常磨损,引起密封失效,导致油压下降,造成转叶式舵机功能丧失.明晰叶片密封件与缸体内壁之间的摩擦磨损机理以及提取关键磨损特征是提高叶片密封件的磨损寿命和实现转叶式舵机智能故障诊断的关键.以常用于制作密封件的聚氨酯高...     

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...     

Wear simulation of spur gears

This paper deals with prediction of wear in spur gears, which has been calculated using an approach in which the wear depth on a tooth surface is integrated over time using the Euler integration method. Variations in pressure distribution over the surface have been considered, as well as changes in curvature and surface profile of the teeth as they wear. The paper focuses on the use of an appropriate wear model for simulating wear using calculated conditions between high-performance slow-running lubricated spur gears. A numerical model for prediction of surface interaction of spur gears developed earlier by the authors has been applied as the basis for the simulation of wear using different wear models. Owing to the nature of the wear models, methods of calculating the contact temperature have been investigated for the specific case of interacting gear teeth. It was found that a linear wear model, when compared with a more complex oxidation model and with a model based on adsorption of lubricant molecules, satisfactorily predicts wear. It was also found that it is the geometry of the gears that causes sliding velocity to be the dominant wear-inducing factor, and so determines the general nature of the wear behaviour.     

Interpretation of Gear Wear

The paper discusses the concept of using morphological examination of wear debris to assess the condition of gears in a gear box. The debris examined was produced by three sets of gears that were tested in two special-purpose gear rigs. The experimental techniques employed were transmission and scanning electron microscopy, optical microscopy, and ferrography. It is suggested that an understanding of gear tooth wear may be soundly based on the role of plastic deformation in the wear process. It is concluded that the links between wear and tooth fracture have yet to be established.     

Integrated wear prediction model for cylindrical gear with variable hyperbolic circular arc tooth trace under mixed elastohydrodynamic lubrication

Cylindrical gear with variable hyperbolic circular arc tooth trace (VH-CATT) is a new type of gear. Sliding wear is the main mode of the surface failure of multiple mechanical parts. Both the lubrication state and contact temperature considerably influence wear characteristics, which may aggravate the transmission performance of gear pairs. Wear, contact temperature, as well as lubrication states are jointly explored. Therefore, an integrated wear prediction model was proposed through taking into account flash contact temperature and surface roughness of VH-CATT cylindrical gears in mixed elastohydrodynamic lubrication. According to the equivalent ellipse contact model of VH-CATT cylindrical gears and tooth surface equation, normal curvature and velocity relations for VH-CATT cylindrical gears were observed, and the normal meshing force was obtained through the consideration of load sharing coefficients and quality grades. Flash contact temperature was estimated by using the literature. This study proposes analytical solutions for investigating how various surface roughness, operation, and geometric parameters affect asperity contact ratio (ACR), asperity contact pressure (ACP), flash contact temperature (FCT), as well as wear depth (WD) related to driving gears. ACR, ACP, FCT, as well as WD initially decrease and then increase from engaging-in to engaging-out processes. The minimum occurs at the pitch point. The WD declines as module, cutter radius, and rotational velocity increase while augmenting when surface roughness and torques increase. The maximum and minimum wear depths in driving gears occur at the dedendum and pitch point, respectively. Its overall wear is reduced by 23.16 % compared to the wear of spur gears. The results are valuable for the studies of tooth pitting, wear resistance, and fatigue life improvement for VH-CATT cylindrical gear. These studies can provide verification data and references required for engineering designs and VH-CATT cylindrical gear operations.

     

齿轮抗磨损强度计算方法研究

基于离散数学原理,建立了渐开线齿轮磨损过程的数值仿真模型,开发了计算齿面动态磨损的软件,可计算与几何形状有关的齿轮参数和所经历时间的定量关系,从新角度解决了他轮抗磨损寿命校核和设计方案比较的计算问题。     

高分子复合材料齿轮磨损模型及磨损测试研究

基于Archard磨损模型,建立高分子复合材料齿轮磨损量模型;分析黏弹性体高分子复合材料齿轮的啮合特性,探讨高分子复合材料齿轮磨损量测量原理。设计了一种高分子复合材料齿轮磨损量测量系统,该系统的测试原理是,通过单铰链支撑的悬臂梁和枢轴箱对齿轮动态加载,使齿轮轮齿表面发生磨损从而导致枢轴箱发生旋转,通过位移传感器测量枢轴箱的偏转角,然后由建立的偏转角与齿轮磨损量之间的关系模型计算得到磨损量。在设计的测试系统上对尼龙66齿轮进行疲劳磨损实验,实验结果和理论模型计算结果基本吻合,既验证了理论模型的正确性,也为高分子复合材料齿轮磨损测试提供了一种新方法。     

渐开线斜齿圆柱齿轮磨损的数值仿真

基于离散数学原理和计算机技术建立了渐开线斜齿圆柱齿轮磨损的数值仿真模型,引入温度对磨损的影响,使仿真更接近于实际的磨损过程,开发出模拟相应磨损过程的软件,实现对磨损过程的动态仿真,解决了动态和非线性磨损问题。通过算例验证,仿真的结果与实际测量的磨损量基本相符。     

主减速器齿轮早期磨损原因分析与改进

从磨料磨损、黏着磨损、主、被动锥齿轮啮合间隙不统一、主动锥齿轮与主齿轴承座连接结构不合理、主、被动齿轮齿面硬度不均匀、差速器轴承预紧力的影响等方面分析主减速器齿轮早期异常磨损原因,通过加强装配控制、改进结构和工艺等措施,有效延长了主减速器的寿命。     

螺杆泵驱动装置磨损状态监测系统

螺杆泵驱动装置受力复杂,振源众多,轴承和齿轮的磨损类故障较为频繁,而常规的单项指标测试只能进行定性分析,诊断精确度不高。为此,开发了磨损状态监测系统。该系统由传感器、诊断仪主机和便携式计算机组成。通过建立设备信息库、故障模式库实现了故障特征自动提取;通过建立磨损状态分级模型,实现了部件的故障诊断及整机磨损状态的评判。实际应用中,诊断出了电机轴承磨损和驱动装置大、小齿轮磨损的故障,表明系统具有较高的应用价值。     

The Slow-Speed Wear Behavior of Case-Carburized Gears Lubricated with NLGI 00 Grease under Boundary Lubrication Conditions

NLGI 00 greases are often used to lubricate gears running at low pitch line velocities, such as, for example, in large open gear drives. At low pitch line velocities, sliding wear, which under these operating conditions is referred to as slow speed wear, is often the limiting factor to gear lifetime. A thorough knowledge of the effect of different grease components on the wear behavior is therefore important when selecting a grease to effectively reduce gear wear in a given gear drive. In order to systematically investigate and analyze the influence of different grease components on the slow-speed wear behavior of case-carburized gears, systematic gear tests using the Gear Research Center's (FZG) back-to-back gear test rig were conducted. Primarily, the focus of the experimental investigations is on the influence of the base oil viscosity and type, the additive type, and also the type of soap thickener on the gear wear behavior at low pitch line velocities. To experimentally determine the influence of these different grease components on the wear behavior of case-carburized gears, a modified, more stringent wear test, based on the standard DGMK slow-speed wear test for gear oils, was developed. Different NLGI 00 greases with base oil viscosities between ν₄₀ = 70 and 1,200 mm²/s were investigated.

Base oil type and base oil viscosity were shown to have only a minor effect on the wear behavior under boundary lubrication conditions. On the other hand, the thickener type and especially the additive type play an important role in determining the wear behavior.     

The wear behaviour of polymer composite gears

In order to examine the wear of polymer composite gears, a test facility has been developed which has enabled the wear of gear trains to be measured continuously during gear operation. Brief details of the method are given. The purpose of this paper is to report some of the results obtained from this facility and, in particular, to discuss the effect of temperature on the wear of acetal gears.     

Antiwear performance of modern industrial gear oils

Thermally refined gears were tested under the effects of various modern industrial gear oils, viscosity 1SO VG 220. The wear of the gears was measured for each oil, including tooth surface roughness and the tooth fillet strain of the pinion. It is concluded that graphite additivated gear oil shows excellent wear resistance and surface roughness over sulphur-phosphorus and organic Mo compound added oils, as well as less iron oxide.     

Wear of gear of circular-arc tooth-profile: effect of helix angle and oil viscosity

The results are presented of an experimental investigation carried out at Mansoura University Laboratories aimed at studying the effect of change of helix angle and lubricating oil on wear of a relatively new type of gearing of circular-arc tooth-profile. Eighteen pairs of gears of 6 DP, 91.5 mm pitch diameter and different helix angles were run in power circulating gear test rig at different speeds and transmitting different loads, and the gears were lubricated with oils of different viscosities. It was found that wear increases with increasing helix angle and decreases with increase of oil viscosity. Variations of amount of wear with all the test variables are presented.     

机械零件磨损仿真与概率寿命估算

基于离散数学理论和计算机技术,用数值仿真方法,建立通用数值仿真模型。提出磨损概率寿命概念,利用Monte Carlo法,以斜齿圆柱齿轮摩擦副磨损状态为研究对象,通过算例实现对斜齿圆柱齿轮机构磨损失效概率寿命分布的计算,解决了零件磨损概率寿命的预测问题,所建立的磨损仿真方法和模型具有良好的工程应用前景。     

Investigation of the effects of alumina nanoparticles on spur gear surface roughness and hob tool wear in hobbing process

Hobbing process is one of the machining methods in manufacturing spur gears. In machining processes, selecting a suitable lubricant is one of the significant factors in enhancing machining productivity and improving the characteristics of manufactured workpieces. This study has used the nanolubricant including alumina nanoparticles dispersed in mineral-based oil 25W-50 in hobbing process. Then, hobbing process using the lubricant including both nanoparticles, and none has been done utilizing with the similar hob tools. Two spur gears with DIN1.7131 material have been manufactured using each of two lubricants. Then, the hob tool wear and surface roughness values of manufactured spur gears were investigated. Comparing the results show that using lubricant including alumina nanoparticles in hobbing process causes an expressive decrease in the hob tool crater and flank wear. Also, arithmetic surface roughness value in spur gears manufactured with nanolubricant has decreased.