热轧层流辊道内冷辊回水结构的优化改进

针对某热轧厂1 580 mm生产线精轧出口层流辊道内冷辊频繁发生操作侧轴承失效问题,对其原因进行了分析,同时核算了内冷辊受热轴向膨胀后操作侧轴承侧向间隙。结果表明:操作侧轴承侧向间隙满足使用要求,轴承失效和辊筒受热膨胀无关;操作侧轴承失效的直接原因是轴套制造精度低导致骨架油封失效、内冷辊高速旋转“吸水”效应,使冷却回水进入轴承座内部,进一步造成润滑不良进而造成轴承失效。为此,对内冷辊回水结构进行了优化改进:在操作侧轴承座端盖和水套之间增加法兰,延长轴套及安装轴套的轴头,在轴头和轴套之间增加O型密封圈。改进后两年的使用周期内没有发生过轴承失效故障。     

数控机床主轴轴承失效分析

某数控机床主轴轴承运行613 h后出现振动异常,发现失效轴承个别钢球表面存在明显损伤痕迹,通过宏微观观察,化学成分分析,能谱分析等方法对钢球表面的损伤痕迹进行研究。结果表明,由于金属异物颗粒进入轴承,异物与钢球发生粘着磨损,随着粘着磨损作用加剧,在钢球表面产生“白层”,“白层”内部萌生接触疲劳裂纹,疲劳裂纹扩展使钢球表面剥落,形成剥落坑,引起轴承失效。失效轴承的各部件硬度差值超出标准,加速了轴承的失效。因此建议对轴承添加防尘盖或密封圈,提高润滑油脂的洁净度,避免外界异物污染轴承引起失效,并在实际生产中加强轴承材料的质量控制。     

SKF滚动轴承的失效分析

送风机电机滚动轴承在运行过程中发生温度骤升而失效.对失效轴承解体表明,A电机轴承内圈表面出现麻坑及剥落;B电机轴承外圈出现断裂.轴承中的润滑脂已硬化失效.采用化学分析、硬度测定、红外光谱、拉曼光谱、X射线衍射、热失重分析、扫描电镜及金相分析等方法对失效轴承及润滑脂进行分析.结果表明,润滑脂的硬化导致了金属摩擦副之间的直接对磨,加重了轴承滚道表面的磨损.A轴承的失效主要是由电蚀所引起;B轴承外圈因表面硬度偏低,易产生磨损,在轴承滚动过程中的交变应力作用下发生断裂.     

轧机油膜轴承的失效故障树分析

以轧机油膜轴承为研究对象,分析了引起其发生失效的各个因素,建立了轧机油膜轴承失效故障树。通过对故障树的定量分析,得出了轧机油膜轴承故障树的各阶最小割集,从而确定了锥套损坏、衬套损坏和润滑油变质为轧机油膜轴承失效的主要形式,并提出了预防轧机油膜轴承失效和提高轧机油膜轴承可靠性的相关措施。     

谐波减速器用柔性轴承疲劳寿命实验与失效分析（英文）

柔性轴承是谐波齿轮减速器的重要组成部分。为了研究柔性轴承的失效特性,研制了一种可进行柔性轴承疲劳寿命实验的专用试验机。该试验机的加载装置能够与柔性轴承的内圈一起旋转,并可在外圈主轴两端同步施加载荷。通过对四套柔性轴承进行疲劳寿命试验,观察到了几种柔性轴承的失效现象。实验后测量了沟道的宽度,深度和表面粗糙度。实验结果表明:柔性轴承的内圈仅在主轴末端出现磨损和疲劳剥落现象,而外圈可能出现疲劳断裂和剥落现象。此外,还发现柔性轴承套圈沟道的磨损是不均匀的。     

谐波减速器用柔性轴承疲劳寿命实验与失效分析

柔性轴承是谐波齿轮减速器的重要组成部分。为了研究柔性轴承的失效特性，研制了一种可进行柔性轴承疲劳寿命实验的专用试验机。该试验机的加载装置能够与柔性轴承的内圈一起旋转，并可在外圈主轴两端同步施加载荷。通过对四套柔性轴承进行疲劳寿命试验，观察到了几种柔性轴承的失效现象。实验后测量了沟道的宽度，深度和表面粗糙度。实验结果表明:柔性轴承的内圈仅在主轴末端出现磨损和疲劳剥落现象，而外圈可能出现疲劳断裂和剥落现象。 此外，还发现柔性轴承套圈沟道的磨损是不均匀的。     

奥克斯纳立泵滑动轴承副的失效分析

对奥克斯纳立泵滑动轴承副进行了失效分析。结果表明:该轴承副的失效是由于选材不当造成。轴承副的内外轴套WC硬质合金层的粘结剂Co被温热的稀硫酸溶解造成WC粒子脱落,并加速了轴套的磨损。在WC层被磨掉后,内轴套基体材料UB_6因温热磷酸和Cl~-腐蚀和机械磨损引起失效破坏。     

汽车轮毂轴承的断裂失效分析

通过外观检查、成分测试、硬度测试、金相组织和扫描电镜观察等方法,对某品牌汽车3个轮毂轴承失效件进行分析,找出了造成轮毂轴承最终断裂失效的原因。结果表明,3种轮毂轴承的内圈和外圈的组织都符合JB/T 1255-2001标准的要求;1#轮轴轴承失效的原因是由于化学成分不合格和轴承内圈滚道的表面硬度较低;2#轮毂轴承的化学成分、硬度和组织都满足要求,失效原因在于密封性较差,而使得外圈滚道中外界硬度相对较高的颗粒落入滚道,造成磨损加剧;3#轮毂轴承外圈碳含量较低,使得外圈滚道表面硬度偏低,且由于润滑条件不好引起了粘着磨损,加剧了轴承的磨损,并最终造成失效。     

特大型四列圆锥滚子轴承失效分析

针对国内某钢厂穿孔机用特大型四列圆锥滚子轴承出现异响、轴承失效的问题,对失效轴承进行了外观、金相组织、外形尺寸和硬度检查,判定轴承材料、表面硬度符合标准。分析认为裂纹为大挡边与滚子端面剧烈摩擦发热所致。尺寸变形因安装拆卸时对轴承的加热冷却措施不当所致。安装时中外圈的倾斜导致了轴承各列游隙不均,导致B列受力较大最终失效。指出多列轴承安装时需注意对各列游隙的控制。     

G20Cr2Ni4A轴承滚动体开裂失效分析

G20Cr2Ni4钢轴承滚子是安装在大型轴承上作为滚动体使用的,该滚子经表面渗碳后再经淬火回火处理。送检的滚子在试车约2 h后断裂,造成轴承失效。采用金相显微镜、洛氏硬度计、扫描电镜、X荧光光谱仪等,对该轴承滚子的开裂原因进行了分析。结果表明:金相组织、硬度、渗碳层厚度和化学成分等均合格。氢脆引起的内应力与外应力叠加是造成滚动体由内向外疲劳开裂失效的主要原因。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.