基于胎面扰动的轮胎多边形磨损机理探讨

通过建立基于胎面扰动的非均匀磨损动力学模型,验证了轮胎多边形磨损可以由胎面扰动引起,分析了基于胎面扰动造成轮胎非均匀磨损的机理,得出多边形磨损边数主要由轮胎的转动频率和胎面的固有频率决定的结论,并得到了轮胎磨损边数的计算公式.     

增速齿轮副非均匀磨损时变啮合刚度研究

以某渐开线直齿圆柱增速齿轮副为研究对象,基于Hertz接触理论与Archard磨损公式,推导齿轮副齿面接触应力与相对滑动速度,建立齿轮副非均匀磨损模型,计算了不同循环次数下齿面磨损深度;基于势能法推导基圆与齿根圆不同位置下轮齿非均匀磨损时变啮合刚度解析公式,研究了非均匀磨损对时变啮合刚度的影响规律。研究结果表明,磨损深度在渐开线齿廓上分布不均匀,节圆附近的磨损最小,齿顶齿根处磨损深度较大,且齿顶处累积磨损深度最大;齿面磨损深度随循环次数增加而增大,齿轮时变啮合刚度随磨损深度增加而减小,且双齿啮合区刚度减小量大于单齿啮合区。     

灰口铸铁面铣加工中修光刃磨损特性的研究

采用具有不同前角和表面处理形式的刀片,对HT250灰口铸铁进行了平面铣削试验。通过观察刀片修光刃处前后刀面的磨损状况,发现修光刃磨损可分为均匀磨损和刀尖破损导致的非均匀磨损两个阶段。结合对切削过程中刃口形貌变化规律的研究,分析了铸铁面铣过程中刀片几何形状、表面处理形式等因素对修光刃磨损特性的影响。     

齿面磨损对齿轮啮合刚度影响的计算与分析

不考虑润滑剂影响,针对理想渐开线直齿圆柱齿轮,研究存在齿面磨损时齿轮啮合刚度的计算方法。基于齿轮共轭啮合原理计算滚齿加工条件下的齿廓曲线。根据Timoshinko梁理论,考虑轮齿弯曲变形、剪切变形、压缩变形、齿轮基体变形和赫兹接触变形,计算齿轮啮合刚度。针对运行过程中的齿面磨损,提出轮齿等弧长离散方法,分析齿面磨损对离散微元短梁的截面面积、截面面积矩和实际接触齿宽的影响,计算分析存在均匀磨损、微点蚀和宏观点蚀等齿面磨损时的齿轮啮合刚度。结果表明,100μm深的均匀磨损导致的啮合刚度变化不到2‰;齿面产生15%的微点蚀时,啮合刚度变化在10%以内,啮合刚度对早期齿面磨损不敏感。本研究为计及齿面磨损的齿轮动力学建模提供了一条技术路径。     

非均匀载荷下磨损套管抗挤强度研究

针对非均匀载荷下套管磨损后抗挤强度降低的问题,将磨损简化为套管的壁厚不均度和内壁不圆度几何缺陷。在此基础上,建立了非均匀载荷下磨损套管抗挤强度计算方程。该方程计算值与试验值的对比表明,该方程计算结果是可靠的,可为复杂地层磨损套管柱设计提供理论依据。研究表明,当载荷不均匀程度较小时,磨损对套管抗挤强度的影响较大;当载荷不均匀程度较大时,磨损对套管抗挤强度的影响较小。     

基于铣削力参数化模型的铣刀非均匀磨损状态监测方法研究

在航空结构件钛合金零件数控加工中,刀具非均匀磨损状态对工件的最终质量影响很大。为了及时发现并控制因刀具非均匀磨损导致的异常加工状态,对钛合金加工刀具非均匀磨损状态监测方法进行了研究。建立了基于刀具刃线参数化模型的铣削力参数化模型,实现了对钛合金加工刀具非均匀磨损状态的监测,解决了零件单件或首件加工中样本数据缺失条件下的钛合金加工刀具非均匀磨损状态准确监测难题。     

边界摩擦和磨损零件的可靠性设计方法

针对处于边界摩擦和干摩擦状态下工作的许多机械零件——铰链、导轨、汽缸和活塞、凸轮、滑动轴承、离合器等的主要失效方式为胶合与磨损,提出防止剧烈磨损、抗胶合和耐磨等三种可靠性设计方法。解决了面大量广的潜水泵推力轴承的可靠性耐磨设计问题。提出的磨损率计算的工程数学模型和可靠性磨损设计法,能用计算方法来预测磨损寿命和磨损量。     

机床滑动导轨的磨损与磨损计算

本文论述了机床滑动导轨的磨损及磨损计算。分析了铸铁—铸铁,铸铁—塑料滑动导轨副的磨损情况和磨损不均匀性;列出了单件小批生产时普通车床和单柱式立式镗床滑动导轨的磨损率i_n和比磨损Ⅰ的数值和计算公式。介绍了机床滑动导轨的工程近似估算和不均匀磨损使用概率的计算方法。     

非均匀磨损套管空间有限元分析

针对非均匀磨损套管进行了空间有限元分析,研究了磨损量、磨损长度、轴向拉力对套管抗内压强度的影响.计算结果表明非均匀磨损套管的抗内压强度随磨损厚度的增加而降低;不同的磨损长度对套管抗内压强度影响不明显,即抗内压强度主要受磨损厚度的影响;套管轴向拉力对其抗内压强度影响不大,并且这种影响随着磨损量的增加而逐渐减小.通过对磨损套管抗内压强度变化规律的研究,为合理制定井控措施提供了科学依据.     

传动齿轮表面磨损过程中油液参数磨损特性分析

油液分析技术能够通过监测润滑油中元素的磨损情况对机械磨损故障进行有效诊断.针对齿轮箱齿面故障,构建齿轮箱磨损试验方案,设计齿轮箱磨损试验方案,并通过700h的齿面磨损试验,取样得到各磨损阶段的典型油样.通过油液分析技术,探寻齿面磨损条件下油液光谱参数和铁谱参数的磨损特性,为齿轮诊断提供较可靠的试验数据.     

小模数,多齿数行星齿轮传动及其在采煤机械中的应用

作者提出与以往齿轮设计配齿原则不同的按小模数、多齿数设计行星齿轮传动的观点。分析了该设计法优点及应用条件，并指出确定模数、齿数的方法。最后，结合ＭＧ３００－ＡＷ１采煤机例子，介绍了实际应用效果。     

干摩擦条件下表面成膜添加剂的应用研究

本文以制动摩擦副为例，讨论了在摩阻材料中添加含氟、硫或铜元素的化合物时，与金属对偶件在干摩擦条件下其表面膜的形成机理，探讨了不同成膜添加剂对摩阻材料的摩擦磨损特性的影响。试验表明：含硫的成膜剂，可减少对偶件表面的磨损，但不利于稳定摩擦系数；而添加含氟和铜化合物的成膜剂，既利于减少对偶件表面的磨损，又可提高摩擦的稳定性。文中提出了在干摩擦条件下，在摩阻材料中添加表面成膜剂是控制或稳定摩擦系数及减少磨损的重要途径，并在实践中得到了验证。     

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.     

基于响应面法的多因素交互作用下中部槽磨损试验研究

为确定影响中部槽磨损的主要因素及交互作用关系，通过中部槽磨损试验，以磨损量为响应值，基于响应面法进行了磨损因素分析。通过Plackett-Burman试验对6个磨损因素进行筛选，发现煤散料含水率、煤散料含矸率及法向载荷对磨损量影响显著。根据中心复合设计(CCD)试验结果建立了磨损量与显著性因素的二阶回归模型，经响应面分析可知，散料含水率是影响磨损的关键因素。对回归模型进行优化，得到显著性对磨损量的预测模型，经试验发现预测模型与真实试验无显著差异(P>0.05)，表明应用响应面法进行中部槽磨损多因素交互作用研究是可行的。     

Tribological Performance Optimization of Electroless Ni–P Coatings Using the Taguchi Method and Grey Relational Analysis

The present article considers an experimental study of tribological performance of electroless Ni–P coatings and optimization of tribological test parameters based on the Taguchi method coupled with grey relational analysis. A grey relational grade obtained from the grey relational analysis is used as performance index to study the behaviour of electroless Ni–P coating with respect to friction and wear characteristics. Experiments are carried out by utilizing the combination of tribological test parameters based on L₂₇ Taguchi orthogonal design with three test parameters, viz., load, speed and time. It is observed that all the three test parameters have significant contribution in controlling the friction and wear behaviour of electroless Ni–P coating. In addition, the interaction of load and time has significant influence on tribological performance. The surface morphology, composition and wear mechanism of the coatings are studied with the help of scanning electron microscopy, X-ray diffraction analysis and energy dispersed X-ray analysis.     

Spalling formation mechanism for gears

Though the basic phenomenon of wear on gear tooth contact surfaces is the removal of a piece of material from the working surface, the sizes of the wear debris may be different, due to the different physical causes in their formation processes. No common definitions have been established to distinguish spalling from pitting in the literature. This is probably due to the fact that the physical causes of pitting and spalling have not yet been established. In this paper, a brief literature review is presented with the intention to differentiate spalling from pitting. Three types of wear phenomena are defined. Furthermore, the results of a recent experimental study of gear tooth spalling formation in AISI 4340 gears in a test rig are also presented to demonstrate a possible process of spalling due to the development of cracks beneath the tooth contact surfaces and crack linkages in plastically-collapsed metal ligament between the crack tip and the adjacent tooth contact surface. These experimental results substantiated the ligament collapse spalling mechanism proposed by Ding et al. [Y. Ding, R. Jones, B.T. Kuhnell, Elastic-plastic finite element analysis of spall formation in gears, Wear 197 (1996) 197-205; M. Heems, F. Lagarde, R. Courtel, P. Sorin, C. R. Acad. Sci. 257 (3) (1963) 3293].     

基于制动器摩擦副销-盘试验的第三体摩擦磨损特性研究

风电制动器因其制动工况多变,摩擦副表面的第三体成分复杂且大小各异,在第三体影响下摩擦副的摩擦磨损特性仍有待研究。以服役期内风电制动器摩擦副为研究对象,对附着在风电制动器摩擦副表面的第三体成分及尺度进行检测。检测结果表明,风电制动器摩擦副表面第三体的主要成分为铁铜磨屑及沙石颗粒,且其尺度均在百微米级。利用销-盘摩擦磨损试验机研究具有上述成分及尺度第三体对摩擦副摩擦磨损特性的影响。试验结果表明：摩擦初期第三体在摩擦副间产生滚动起减摩作用,摩擦因数大幅减小;随着磨损程度的加剧,摩擦因数大幅上升,摩擦副提前进入剧烈磨损阶段;铁颗粒会加剧摩擦副磨损缩短其使用寿命,沙颗粒会导致制动过程摩擦力矩大幅波动,铜颗粒会导致制动力的不足。     

The mechanism of synergism between ZDDP and CeF3 additives

The interaction of zinc dialkyldithiophosphate (ZDDP) with cerium fluoride and cerium dioxide in lithium grease has been studied for friction, wear, and EP characteristics on a four-ball and SRV tester. The combination of ZDDP and cerium trifluo-ride has been shown to be beneficial in reducing wear, especially over a long period of friction and with increasing EP load. The test results show that adding cerium dioxide to lithium grease does not improve the antiwear and friction performance of the paste. The analytical results of X-ray photoelectron spectrum (ESCA, XPS) reveal that ZDDP inhibits the decomposition of cerium fluoride and improves its film-forming property. The wear scar reaches a minimum at an atomic concentration ratio of 3P:2Zn:1S:25F, and an atomic concentration ratio of 2S:2P:1Zn:4F gives the highest EP load. The scratch test results show that combining ZDDP with cerium trifluoride improves the tenacity of the surface film. The stabilisation of cerium trifluoride by ZDDP is proposed.     

Wear of Cobalt Base and Stainless Materials in High Purity Water

Results of wear tests in clean water at room temperature and at 500F are presented. The differences in result with 0.08 in. diameter and line contact riders and with much larger riders are shown. The contact stress range is from 10 psi to 9000 psi for large contact areas and from 3000 psi to over 100,000 psi for small contact areas. The majority of the testing is at a linear velocity of about 2 in. per sec. The concept of wear per unit load and per unit distance traveled for a unit wear area is used for converting sliding wear data from various test machines to a common basis for comparison. The same concept can be used for calculating from wear data the expected wear in a new design. The range and trend of friction values encountered in some of the tests is presented.     

Fretting-induced friction and wear in large flat-on-flat contact with quenched and tempered steel

Fretting may cause severe surface damage and lead to unexpected fatigue failure. Our test apparatus was designed based on reciprocating, large, annular flat-on-flat contact without any edge effects in the direction of the fretting movement. Fretting wear tests were run with quenched and tempered steel with different normal pressures and sliding amplitudes under gross sliding conditions. The development of the friction coefficient and total wear mass depended mostly on the accumulated sliding distance. Initially, friction and wear were highly adhesive but gradually changed to abrasive due to third body accumulation in the interface.