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为研究船舶工况参数对可倾瓦推力轴承稳态和瞬态润滑特性的影响,利用Matlab建立船舶可倾瓦推力轴承热弹流体动压润滑计算模型,考虑轴瓦的热弹性变形,联立黏温方程、能量方程、油膜刚度和阻尼系数方程求解模型,研究热弹性变形以及不同载荷和转速情况下船舶可倾瓦推力轴承的润滑特性。结果表明:考虑热弹性变形时,最小油膜厚度增大,最大油膜压力和最高油膜温度降低;在正常运行工况条件下,轴瓦的热弹性变形有利于改善推力轴承的润滑性能,轴承设计时应考虑材料的抗压性和耐热性;在转速不变时随着载荷的增大,最小油膜厚度降低,最大油膜压力、温度、油膜刚度和阻尼均增加,需要特别注意重载工况下轴承的动压润滑状况;在载荷相同的情况下,随着转速的提高,油膜厚度和油膜温度增大,油膜压力变化不明显,油膜刚度和阻尼随转速增大而降低,在转速较低时下降较为明显。研究结果为优化轴承设计、提高轴承运行的可靠性和稳定性提供参考。 相似文献
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1.维修要点(1)薄壁轴瓦不允许修刮,只能按相应尺寸选配现代发动机曲轴主轴承和连杆轴瓦的耐磨合金涂层均很薄,加工的尺寸精度很高,粗糙度很低,一般不允许修刮,只能按相应的尺寸选配;如果没有合适尺寸的轴承,可采用基孔制的方法磨削曲轴。对于三层合金轴瓦(由钢背-铜铅合金-表层构成),电镀在铜铅合金上的表层合金厚度一般为 相似文献
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钢背复合材料已应用到我厂开放式炼胶机轴瓦上,它代替了贵重的有色金属铜,价格既便宜,安装又方便。其结构是以钢板为基体,以烧结球形青铜粉为中间层,以塑料为摩擦表面层,并能牢固结合为一体的三层结构自润滑材料,如图1。钢背的作用是提供机械强度;多孔青铜是塑料与钢背结合的媒介,同时起到传导摩擦热、增加尺寸稳定性的作用;塑料表面层提供了良好的自润滑和摩擦磨损性能。钢背复合材料是兼有金属和塑料两种材料的优点,有较高的强度,良好的自润滑性能,及尺寸稳定性的新型轴承材料。 相似文献
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气膜厚度是波箔径向空气轴承的一项重要性能参数,对轴承的承载能力和工作稳定性产生重要影响.提出了一种波箔径向空气轴承稳态工况气膜厚度最小值的测量方法,并对不同工况的轴承气膜厚度进行了测量.结果表明:膜厚随转速的升高有逐渐增大的趋势;相对于轴承载荷,转速对膜厚的影响更大. 相似文献
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为了得到直升机分扭传动输入级角接触球轴承的疲劳寿命,综合考虑了热应力和结构应力的共同作用。基于L-P疲劳寿命理论和Hertz接触理论,结合Goodman公式、材料的P-S-N曲线以及Miner疲劳累积损伤理论的EM修正法则,建立了直升机主减速器角接触球轴承的疲劳寿命模型。分析了角接触球轴承摩擦发热量的计算和对流换热系数的选取,确定了要加载的热载荷和边界条件,基于Ansys软件对轴承进行稳态热分析,分析径向载荷与转速对轴承稳态最高温度的影响。并在稳态热分析的基础上进行轴承热机耦合场分析,探讨了温度影响下的轴承疲劳寿命。结果表明:随着工作温度的升高,轴承寿命明显降低,摩擦发热对寿命的影响不可忽视。 相似文献
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Boncheol Ku Youngdo Park Chiun Sung Youngchul Han Junghoon Park Yujin Hwang Jungeun Lee Jaekeun Lee Hyeongseok Kim Sungyoung Ahn Soo Hyung Kim 《Journal of Mechanical Science and Technology》2010,24(8):1631-1635
This study examined the tribological behavior of journal bearings made from polytetrafluoroethylene (PTFE) composites and aluminum (Al) alloys. The PTFE composite journal bearings consisted of a steel backing with a thickness of 1.6 mm, a middle layer of sintered porous bronze with a thickness of 0.24~0.27 mm, and a surface layer of PTFE filled with fluorinated ethylene propylene (FEP) powder and carbon fibers with a thickness 0.06~0.14 mm. The other was an aluminum alloy journal bearing consisted of a steel backing with a thickness of 1.5 mm and a surface layer of an Al-6Sn-6Si alloy with a thickness 0.35~0.75 mm. A series of lubrication tests were performed using a journal bearing tester under various normal loads. The tribological properties for each journal bearing were evaluated by measuring the lubricant oil temperature and friction coefficient as a function of the applied normal load. In addition, the chemical compositions and microstructures of the journal bearing materials used in this study was analyzed by inductively coupled plasma (ICP), optical microscopy (OM), and scanning electron microscopy (SEM), respectively. The experimental results showed that the Al alloy journal bearings reduce the friction coefficient by 28 % compared to the PTFE composites bearings. In addition, the Al alloy journal bearing worked properly at the maximum load of ~ 8,000 N without adhesion. However, the PTFE composite journal bearings exhibited strong adhesion at the loads ranging from 6300 to 8000 N. This suggests that the Al alloy is a more promising material in journal bearings than PTFE composites. 相似文献
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M. Khalid Imran S. H. Masood Milan Brandt 《The International Journal of Advanced Manufacturing Technology》2011,52(9-12):855-863
In high-pressure die casting, cooling time greatly affects the total cycle time. As thermal conductivity is the main governing factor, a higher thermal conductive die material allows faster extraction of heat from the casting, thus resulting in shorter cycle time and higher productivity. This paper presents a novel approach to replace a conventional steel die by a bimetallic die made of Moldmax copper alloy coated with a protective layer of steel using laser cladding technology, direct metal deposition on the cavity surface for high-pressure die casting of aluminum alloys. Study includes the investigation of suitable steel layer thickness on Moldmax substrate in terms of porosity, hardness, presence of copper content, and copper particle. Results obtained from the scanning electron microscope and energy dispersive spectroscopy display a metallurgicallly sound and fully dense steel layer on copper alloy. Results of finite element heat transfer analysis also show that bimetallic die offers superior thermal performance compared with monolithic steel die. 相似文献
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The wear pattern of working rolls that accompanies the hot graded rolling of electric copper in a combined process of casting and deformation has been studied. The depth of the worn layer over the contour of grooves in the first four rolling passages were measured. The increased wear of the grooves that roll the metal at the highest temperature has been revealed. The areas of wear localization over the contour of grooves have been stated. A conclusion has been drawn on the significant differences in the wear pattern during the rolling of steel and copper. It has been revealed that wear during electric copper rolling happens due to the flame erosion of the surface layers of rolls made from heat-resistant steel, as well as due to the intensive adhesion of copper to them; furthermore, there is hardly any mechanical or abrasive wear. Recommendations on the need to develop a special material for manufacturing rolls just for copper rolling have been made. 相似文献
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白层是高速硬切削的特有现象,对加工表面完整性和零件的服役性能有着重要影响。针对高速硬切削加工表面白层问题,进行了对GCrl5淬硬轴承钢高速硬切削试验和表面白层测试,研究了不同切削条件下的白层形成机理,分析了切削速度和刀具磨损状态对白层特征的影响规律。分析结果表明,白层厚度随切削速度和后刀面磨损的增大而增大,而其分布的均匀性和连续性也将变差;切削速度和后刀面磨损的增加引起切削温度升高,导致加工表面快速淬火效应,使得白层厚度增大,其中切削速度的影响较为显著;在切削速度较低(100 m/min左右)时白层的形成机理主要为塑性变形,切削速度超过300 m/min则主要是马氏体相变所致,而在中间切削速度(200 m/min左右)时为2种机理的混合作用结果。 相似文献
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为分析热效应对多孔环面接触复层含油轴承流体润滑性能的影响,建立环面接触复层含油轴承系统的热流体动压润滑模型,数值分析轴承系统的温度场及速度场分布,讨论考虑热效应时的复层含油轴承流体润滑问题及其生热、传热机制。结果表明:从轴承底面到摩擦对偶面,温度呈先升高后降低趋势,径向上温度随着半径增加而升高,系统的最高温度位于油膜区外环面上的最小膜厚处;轴承系统中的热量主要由油膜相对剪切发生,周向相对运动速度是系统生热的主要影响因素,温度与周向速度的分布形态相似,油膜产生的热量通过对流换热逐渐向多孔轴承中传导,轴承表层厚度或渗透率降低,对流换热效果变差,轴承系统中温度升高,热效应对润滑性能的影响变大;考虑热效应后,油膜润滑性能变差,但数值分析精度提高,数值结果更接近试验实测值。 相似文献
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The physical process involved in the rubbing of copper on emery paper resembles the dry sliding wear of copper against SAE 1045 steel. In both cases the top layer of the contact surface, the thickness of which is different for the two processes, is heavily deformed. The heavily deformed material can recrystallize dynamically in accordance with the Zener-Hollomon parameter. When copper undergoes this process at room temperature at high strain rate and high strain, very small grains are formed in the top layer of the rubbed surface. At liquid nitrogen temperature the copper partially recrystallizes dynamically in accordance with the Zener-Hollomon parameter. The occurrence of dynamic recrystallization results in a surface layer with very low residual stresses, high toughness and high hardness. These qualities are desirable in manufactured surfaces. 相似文献