渐开线圆柱齿轮抗胶合可靠性计算

本文在油膜厚度法的基础上对圆周速度小于４ｍ／ｓ的渐开线圆柱齿轮进行抗胶合可靠性分析和计算，能在给定抗胶合可靠度的情况下，确定啮合齿面的粗糙度Ｒａ１、Ｒａ２或在已知Ｒａ１、Ｒａ２的条件下，估算齿轮的抗胶合可靠度。     

齿轮传动抗胶合模糊可靠性分析与计算

阐述了一般工程机械的齿轮传动抗胶合可靠度的计算，分析了可靠度计算中的模糊性，给出了抗胶合模糊可靠度的计算公式，并以实例予以说明。     

反推齿轮胶合临界温度可靠性的试验研究

本文提出了用闪温准则反推齿轮胶合临界温度的计算方法，进行了大量齿轮抗胶合承载能力试验，根据试验结果对５０号机械油的临界温度进行了反推计算，分析和对比结果表明，该计算方法是可靠的，试验方案设计是合理的，为确定各类油品润滑时齿轮胶合临界温度奠定了基础。     

国外文摘选编

在重载直齿圆柱齿轮中,齿廓通常要修形。计算修形齿轮的抗胶合能力是一个必须解决的重要问题。本文作者利用功率封闭式齿轮试验台研究了具有不同径向变位量的齿廓修形及齿廓不修形齿轮的抗胶合能力。齿廓修形可大大提高具有小径向变位量齿轮的抗胶合能力。本试验中所采用的轮齿材料和润滑剂的情况下,胶合的表面临界温度为443～447K。通过表面临界温度的计算,可以精确地预计齿轮的抗胶合能力     

渐开线圆柱齿轮抗胶合可靠性计算

本文在油膜厚度法的基础上对圆周速度小于4m/s的渐开线圆柱齿轮进行抗胶合可靠性分析和计算。能在给定抗胶合可靠度的情况下,确定啮合齿面的粗糙度R_(a1)、R_(a2),或在已知R_(a1)、R_(a2)的条件下,估算齿轮的抗胶合可靠度。     

硬齿面齿轮胶合失效载荷级与干摩擦系数及合金元素含量的关系研究

针对我国齿轮胶合承载能力计算方法标准等同采用ISO相关标准,其主要计算及试验数据是否适用于国产齿轮材料及加工工艺的问题,对国产6种硬齿面齿轮材料,采用FZG齿轮试验机法及MM-200滚子摩擦磨损试验机法,分别进行了齿轮胶合失效载荷级、滚子干摩擦系数测试及材料中合金元素的含量分析,提供了齿轮胶合强度计算用的抗胶合承载能力试验数据。研究结果表明:采用干摩擦系数来估算处于边界润滑状态的齿轮胶合失效时的齿面赫兹应力是可行的;硬齿面齿轮材料中,合金元素含量对材料的导热系数及硬齿面齿轮胶合承载能力影响较大;相比其它5种经渗碳淬火处理的齿轮材料,经离子氮化处理的25Cr2MoV材料有着较高的抗胶合承载能力。     

高速齿轮传动CAD系统中胶合承载能力模块的实现

根据国家标准GB/Z6431.2-2003胶合承载能力计算方法将高速齿轮设计过程中胶合承载能力校核计算实现程序化并添加到高速齿轮传动CAD系统中,在高速齿轮传动设计中,只需输入和选择一定数量的已知数据就可以迅速、准确地进行胶合承载能力计算,提高了高速齿轮传动CAD系统中的设计可靠性。重点探讨了数据库的建立、计算机程序的编制。通过计算实例讨论了所提及方法的效率。     

齿轮传动抗胶合机理探讨

本文根据齿轮传动发展的要求及摩擦化学的迅速发展，对目前使用的胶合计算方法提出异议。文章中论述的温度准则、最小油膜厚度准则不适用，应当建立新的抗胶合准则。文章论证了新的抗胶合机理——在接触面上及时形成足够厚的反应膜。并提出当前解决抗胶合的具体办法。     

油池润滑齿轮本体温度计算新公式

针对现有齿轮胶合强度中本体温度计算方法的不足，根据热网络理论建立了油池润滑齿轮热网络简化计算模型，确定了三种热源及热阻的计算公式，解决了润滑油与箱体面强迫对流换热阻这一难点，给出了油池润滑齿轮本体的一般估算方法；通过引入函数化温升载荷比系数，首镒获得了条件一定时既计及载荷双考虑速度的本体温度的计算新公式，使油池润滑齿轮本体计算更加准确和适用，丰富了ＩＳＯ齿轮抗胶合承载能力计算方法。     

齿轮胶合的计算和试验研究

根据基于系统和时变观点的齿轮胶合机理分析［１］，研究了齿轮传动的啮合特点，并以非稳态齿轮本体温度场的有限元分析，计算了齿轮本体温度场的分布，结合文献［２］的研究结果，建立了齿轮传动的胶合计算方法。还介绍了作者进行的齿轮胶合试验，试验结果表明：利用本研究的计算方法得到的胶合载荷与试验结果基本相符，试验结果还表明：在同一种“油－材料”组合下，由作者设计的齿轮温度测量装量测出的发生初期胶合时的齿面温度不是一个常数，它与转速、扭矩、运转方式及油量等都有很大关系；初期胶合发生后，齿轮传动还可继续工作。因此本研究认为，监测初期胶合，对于防止齿轮传动发生胶合、咬死等重大损坏有重要意义。     

Comparative analysis based on adiabatic shear instability for scuffing failure between unidirectional and reciprocating sliding motion

The principal goal of the experiments described here is to study the sliding motion effects on the scuffing life on the basis of adiabatic shear plastic instability. Experimentally we observed that the load capacity of the surface decreased and micro-scuffing initiated frequently under the reciprocating sliding motion as compared to under the unidirectional sliding motion. According to the adiabatic shear instability model, the scuffing initiation occurs when the rate of thermal softening exceeds that of work hardening due to plastic deformation. In order to ascertain the thermal softening in sliding surfaces, the contact temperatures were calculated. We found that the higher friction coefficient under the reciprocating sliding motion caused the higher contact temperature than that under the unidirectional motion. Therefore, the rate of thermal softening could exceed that of work hardening easily under the reciprocating sliding motion owing to frictional heating. We speculated that the scuffing initiation could roughen the sliding surfaces rapidly under the reciprocating sliding motion and confirmed that our assumption demonstrated above, was consistent with the experimental observation. In conclusion, there is a synergy effect in relation to scuffing failure because the frictional heating, surface roughening, and scuffing initiation function together to enhance each other, and consequently, the load capacity of surfaces could decrease under reciprocating sliding.     

Effect of temperature on the scuffing load capacity of EP gear lubricants

Scuffing of gears involves the welding together of locally unprotected metal‐to‐metal contacts when critical limits of pressure and temperature are exceeded. Protection can be maintained by a thick lubricant film, by physically adsorbed layers, or by chemical reaction layers. At higher temperatures, viscosity and film thickness decrease but, using an EP gear oil, due to higher chemical reactivity, the scuffing load capacity is not necessarily reduced accordingly. The reaction temperature of the additives is not always reached for large gears. In this paper the factors that influence the scuffing load capacity are investigated, and test possibilities and calculation methods are outlined.     

Scuffing failure analysis and experimental simulation of piston ring–cylinder liner

The scuffing failure phenomenon of piston ring–cylinder liner is studied theoretically and experimentally. The load and bulk temperature when scuffing failure occurs are measured under different engine speed, lubricant, and environmental temperature in a bench test. Based on the experimental results, the asperity capacity when scuffing occurs is evaluated. Surface contact temperature is determined with the measured bulk temperature and the surface flash temperature calculated by Blok theory. The scuffing failure threshold of piston ring–cylinder liner is established by using specific oil film thickness. This revised version was published online in June 2006 with corrections to the Cover Date.     

A scuffing load capacity test with the FZG gear test rig for gear lubricants with high EP performance

Methods for the evaluation of the scuffing load capacity of EP lubricants of API GL-4 and GL-5 performance levels have been developed for the standard FZG gear test rig, which has a centre distance of a = 91.5 mm. Procedure A10/16.6R/90 is capable of discriminating between industrial gear oils and automotive gear oils up to GL-4 performance level while procedure S-A10/16.6R/90 can be applied to GL-4 and GL-5 lubricants. The test methods were verified with reference oils and commercial gear lubricants. The results of the tests can be used to give a relative ranking of reference and candidate lubricants. They can also be used as limiting values in the scuffing load capacity rating method according to DIN 3990 (ISO DIS 6336).     

基于遗传算法的圆柱齿轮变位系数的优化选择方法

合理地选择和分配齿轮传动机构中两齿轮的变位系数 ,能较大幅度地提高其齿面接触疲劳强度与齿根弯曲疲劳强度 ,减轻齿面磨损及防止胶合 ,从而设计出承载能力大、效率高、体积小、重量轻的齿轮机构。鉴于遗传算法的特点 ,提出了基于 GA的圆柱齿轮变位系数的优化方法 ,优化计算实例说明了该方法的可行性     

A method for testing lubricants under conditions of scuffing. Part II. The anti-seizure action of lubricating oils

This paper describes an investigation of lubricating oils under extreme-pressure (EP) conditions in a specially modified four-ball tester. A new test method developed at the Tribology Department of ITeE described in Part I of this paper was used. In this, during a test run, the applied load is increased continuously and the friction torque is measured. A sudden increase in the friction torque indicates the collapse of the lubricating film — where scuffing is initiated. The load at this moment is called the scuffing load. If the load is increased further, it is possible to observe scuffing propagation until seizure occurs, i.e., a defined, maximum friction torque is reached. Thus, scuffing is considered as a process leading to seizure. Using the method, tribological experiments were performed employing various lubricating oils consisting of viscosity-index improvers and antiwear (AW) and extreme-pressure (EP) additives added to a base oil. Mineral and synthetic base oils of different kinematic viscosities were used. The aim was to investigate the influence of such lubricants on scuffing initiation and propagation with the present methodology. In Part I it was shown that scuffing initiation depends strongly on the kinematic viscosity of the lubricant; the higher the viscosity, the greater the scuffing load. The presence of AW and EP additives in the lubricant increases the scuffing load significantly. It was also shown that the kinematic viscosity of the lubricant oils has no effect on scuffing propagation. However, scuffing propagation is significantly mitigated by AW and, to a greater extent, by EP additives. The results of surface analyses show the decisive nature of the chemical reactions of AW and EP additives with the steel ball surface under scuffing conditions, as well as the possible diffusion of sulphur and phosphorus. Chemical reactions and diffusion lead to the creation of an inorganic surface layer (probably iron sulphide), the good anti-seizure properties of which limit scuffing propagation.     

Failure criteria in thin film lubrication with EP additives

The scuffing behaviour of sliding couples made from 12 NiCr 13 steel, lubricated with SAE 90 and SAE 20 W30 oils with and without additives, was studied as a function of relative sliding speed and bulk oil temperature. It was found that the scuffing load decreases almost inversely with sliding speed. Calculations which take into account the decrease in hardness at increasing temperature show a fairly good constancy of total contact temperature (bulk + flash temperature) at scuffing (i.e. values ranging from 550 ° to 650 °C for all oils and test conditions). At low speeds (up to 1 m s^?1) a well-defined increase in scuffing load was found when EP additives were used; at higher speeds this effect was found to have vanished completely. Variations in nominal contact pressure in the range 1 to 3 had no appreciable influence on the scuffing load, indicating that, in the present case, scuffing was associated with a transition from the boundary lubrication regime to the severe wear regime.     

Minimised gear lubrication by a minimum oil/air flow rate

The objectives of the research project were to investigate the limits concerning possible reduction of lubricant quantity in gears without detrimental influence on the load carrying capacity.The investigations covered the influence of the oil level in dip-lubricated systems as well as the oil flow rate in spray-lubricated systems namely oil/air supply systems on power loss, heat generation and load carrying capacity. The load carrying capacity in terms of characteristic gear failure modes was determined and was compared to the results using conventional and reduced lubricant volumes with dip lubrication.Therefore in back-to-back gear tests the parameters speed, load and oil quantity were varied for examination of the four main gear flank damages: scuffing, wear, pitting and micro-pitting. The investigations showed the application potential of oil/air lubrication also for heavy duty transmissions nevertheless there exists a natural limitation for lowering the oil quantity in transmissions without detrimental influence on the load carrying capacity.     

A review of scuffing models

The mechanism of wear known as scuffing has been a research topic of great interest for many years. However, the question of how scuffing is initiated and the factors that contribute to its occurrence are still poorly understood. In general, it can be said that scuffing manifests itself as the sudden failure of lubricating films in mechanical equipment operating under extreme conditions of load and/or speed. Components such as cams, tappets, gears and piston rings are all prone to scuffing failure. Understanding the mechanisms that initiate failure would enable the development of criteria for scuffing prediction. This paper reviews the numerous scuffing models and theories that exist today and, in doing so, defines the important factors involved in scuffing initiation. Emphasis is given to existing theoretical scuffing models which have been correlated by a wealth of research data obtained from experimental test rigs.