风机齿轮箱齿轮失效分析

某发电厂的风力发电机在运行中齿轮箱出现故障,经现场检查发现在风机某一级传动齿轮中有一个齿轮出现断齿现象,断裂部位在轮齿的中间腰部位置.为了判断风机齿轮箱的断裂性质及原因,对风机齿轮箱断齿残片进行了宏微观观察,对断齿残片基体及断口源区进行了能谱分析,测定了断齿表面残余应力,还对齿轮进行了断口定量分析.结果表明,风机齿轮箱齿轮轮齿失效性质为弯曲疲劳断裂.可基本排除齿轮设计、材质、使用维护方面的异常,齿轮断裂原因在于断裂部位存在夹渣缺陷.     

尾减输入齿轮疲劳失效分析

对某发动机尾减系统尾减输入齿轮疲劳失效的原因进行了系统的分析。通过宏观检查、断口分析、金相检验以及受力分析等,确认了该齿轮的失效过程为：在大弯曲载荷作用下疲劳裂纹于锥齿中部齿根部位起始,裂纹初期沿径向呈15°左右的小角度疲劳扩展;齿部出现裂纹后,齿轮振动频率发生变化,进而导致齿轮出现节径型振动,使得裂纹逐渐沿径向疲劳扩展;出现径向裂纹后剩余齿由于截面减少以及起始部位已基本无渗碳层其强度较低等原因,导致剩余齿出现弯曲疲劳断裂。     

减速器主动齿轮断裂失效研究

本文对减速器主动齿轮断裂行为进行了分析。结果表明,齿根倒圆与齿面交接处部位的两长裂纹由大应力造成,裂纹分布、走向及扩展均具有节径型共振特征。辐板与齿轮外圆端面交接处的两小裂纹与二者之间的组织应力有关。     

立式高速泵齿轮断齿分析

立式高速泵在进行出厂前水力试验时，低速轴上的大齿轮和中轴小齿轮的轮齿发生断裂。对齿轮材料的化学成分、金相组织、力学性能、齿轮硬化层深度及断口进行了分析。认为，齿轮轮齿断裂性质为疲劳断裂；断裂原因系工作时受力过大所致，所受力为脉动偏载力。     

12CNi3A钢齿轮断裂分析

材料为12CNi3A的减速器主动齿轮在发动机300h交付试车第十阶段时发生断裂。采用透射电镜和电子探针对断裂齿轮进行了分析，认为齿轮断裂属于疲劳损伤。     

小螺旋锥齿轮断裂失效分析

对小螺旋锥齿轮的断裂失效进行了分析，结果表明，齿轮在传动中出现偏载，造成了连续冲击过载，而使齿轮过早疲劳断裂，本文还讨论了造成偏载的可能性。     

蜗轮连接螺栓断裂失效分析

装卸料机上的蜗轮连接螺栓材料为35钢,强度等级为10.9级,在设备运行大约10a后发生断裂。对断裂螺栓进行宏观、化学成分、硬度、金相、能谱和断口分析后得出,该螺栓的断裂性质为双向弯曲疲劳断裂,螺栓表面的脱碳和螺纹颈部的应力集中降低了该部位的疲劳性能。通过综合分析和螺栓受力估算后得出,螺栓断裂的主要原因是螺栓和内齿轮螺栓孔之间存在较大的间隙,使螺栓的受力状态和受力大小过早地发生了变化,造成连接螺栓疲劳断裂。     

传动渗碳齿轮断裂失效分析

对齿轮的断裂部位的形貌特征,齿面加工情况等进行观察,从断裂区组织与硬度、齿轮材质、渗碳层深度等方面对断裂的渗碳齿轮进行检测、分析。分析结果表明,齿轮断裂是由于淬火裂纹引起的。     

分动箱齿轮断裂原因

某分动箱的20CrMnTi钢齿轮在工作过程中发生断裂。采用宏观分析、微观分析、化学成分分析、硬度测试、硬化层深度测量、非金属夹杂物分析、金相检验等方法对齿轮的断裂原因进行了分析。结果表明:齿面上残留的加工刀痕导致应力集中,在周期载荷的作用下,疲劳裂纹源首先在残留的加工刀痕较深处形成,随后裂纹逐渐扩展,最终齿轮发生疲劳断裂。     

柴油机齿轮失效分析

对断裂齿轮的宏观形貌、显微组织、化学成分及硬度等进行了检验和分析,发现该齿轮的齿根处有明显的黑色网状组织,这种组织严重降低了齿轮的正常使用性能,是造成齿轮早期断齿失效的主要原因.     

变速箱六档齿轮断裂分析及解决措施

对频繁出现轮齿早期断裂的变速箱六档齿轮进行了分析。通过对齿轮断裂特征、显微组织、硬度等方面的综合分析,确定了其断裂形式为低应力高周疲劳断裂。由裂纹扩展过程判断齿轮轮辐设计强度不足是导致其大批量早期疲劳失效的根本原因。据此通过改进齿形、油孔等设计措施,降低齿根部的设计应力水平,解决了这一问题。     

压力机偏心齿轮主轴断裂分析

采用扫描电镜及光学显微镜对压力机偏心齿轮主轴断口进行了系统的分析。确定了主轴断裂属于疲劳断裂,并具有低周疲劳断裂的特征。找出了齿轮主轴断裂的主要原因－主轴油孔处的奕力集中以及超负荷运行造成轴的工作应力过大引起断裂。     

HXD1机车牵引电机转轴组件断裂失效分析

HXD1型电力机车的牵引电机转轴和小齿轮轴采用圆锥过盈配合传动结构(下称转轴组件),使用中该组件出现了早期断裂失效.本文通过理化检测、断口和配合面宏/微观形貌观察等失效分析技术对失效组件进行了分析.结果表明,材料成分、组织和显微硬度正常,小齿轮轴和电机转轴的失效形式分别为高周疲劳断裂和微动疲劳断裂.造成组件失效的原因和过程是,小齿轮轴近齿端油槽-油孔交界线处有较大的结构应力集中,油槽底部周向加工刀痕造成附加应力集中,在应力集中和旋转弯曲疲劳载荷作用下油孔边两个应力集中点萌生了疲劳裂纹并扩展;随小齿轮轴裂纹的不断扩展转轴组件结构刚度减小,继而诱发了与小齿轮轴匹配的电机轴配合面的微动疲劳,电机轴疲劳裂纹萌生于微动区的边缘处;电机转轴先于小齿轮轴完全断裂.基于本文的分析结果提出了提高组件抗疲劳断裂的技术措施.     

Interior fatigue fracture of gear teeth

A new type of gear tooth fatigue failure is presented and analysed. It is initiated in the interior of the tooth and is given the self-explanatory name tooth interior fatigue fracture (TIFF).
A fractographic examination of TIFF is presented. The fracture surface of TIFF has characteristic features that distinguish it from other gear failures.
A hypothesis for TIFF initiation is presented. The crack-initiating stresses in the interior of the gear tooth are: (i) a residual tensile stress due to case hardening; and (ii) alternating stresses due to idler usage of the gear.
A finite element analysis is used to compute the stress state history of engaging gear teeth throughout the load cycle. The critical plane fatigue criterion of McDiarmid is employed. The analysis shows that the risk of fatigue initiation is high in the root of the tooth and in a large region in the interior of the tooth. These findings agree with test results where both modes of failure occurred.     

Failure analysis on fracture of worm gear connecting bolts

The worm gear connecting bolts of refueling machines of a nuclear power plant, with implementing standard of ANSI/ASME B18.3 and ASTM A574-08 and strength grade of 10.9, fractured at the thread neck position after running for about 10 years, and means such as macro examination, chemical compositions analysis, hardness testing, metallographic examination and fracture analysis, were used to analyze the fracture property and reasons of the bolts. The results show that the fracture of the bolts is due to two-way bending fatigue fracture. Surface decarburization of the bolts and stress concentration at the bolt thread neck decreased the fatigue strength of this position and resulted in the initiation of fatigue cracks. By comprehensive analysis and stress estimating, it was concluded that the main reason for fracture of the bolts is that there was a big gap between the bolts and the bolt holes, which resulted in fatigue fracture of the worm gear connecting bolts.     

齿轮箱轴断裂分析

采用化学成分分析、断口分析、金相检验和力学性能测试,对某齿轮箱轴发生断裂的原因进行了分析。结果表明：其断裂模式为疲劳断裂,起源于退刀槽尖角位置,直角退刀槽造成应力集中产生疲劳裂纹;而原材料的锻造和热处理工艺不合理,加速了轴的疲劳断裂。     

A NEW MODEL FOR THE NUMERICAL DETERMINATION OF PITTING RESISTANCE OF GEAR TEETH FLANKS

Abstract— A numerical model for determining the pitting resistance of gear teeth flanks is presented in this paper. The model considers the material fatigue process leading to pitting, i.e. the conditions required for crack initiation and then simulation of fatigue crack propagation. The theory of dislocation motion on persistent slip bands is used to describe the process of crack initiation, where the microstructure of a material plays a crucial role. The simulation of crack growth takes into account both short crack growth, where the modified Bilby, Cottrell and Swinden model is used for simulation of dislocation motion, and long crack growth, where the theory of linear elastic fracture mechanics is applied. The stress field in the contact area of meshing spur gear teeth and the functional relationship between the stress intensity factor and crack length are determined by the finite element method. For numerical simulations of crack initiation and crack propagation in the contact area of spur gear teeth, an equivalent model of two cylinders is used. On the basis of numerical results, and with consideration of some particular material parameters, the service life of gear teeth flanks is estimated. The developed model is applied to a real spur gear pair, which is also experimentally tested. The comparison of numerical and experimental results shows good agreement and it can be concluded that the developed model is appropriate for determining the pitting resistance of gear teeth flanks.     

变速箱双联齿和512齿轮失效分析

某型号变速箱在台架试验过程中,双联齿和与之啮合的512齿轮均发生失效事件。采用断口分析、金相检验、硬度测试以及化学成分分析等方法对失效件进行了检验。结果表明:由于双联齿和512齿轮的齿面存在严重的异常接触,加之双联齿的有效硬化层深度和心部硬度均低于技术要求,从而导致在台架试验过程中双联齿表面发生严重的接触疲劳剥落,与之啮合的512齿轮发生弯曲疲劳断齿。