挖掘机销轴断裂分析

利用宏观检验、断口分析、化学成分分析、金相检验以及硬度检测等方法,对42CrMo钢挖掘机销轴的断裂原因进行了分析。结果表明:销轴断裂为双向弯曲疲劳断裂。由于销轴表面存在较脆的白亮层ε相,且白亮层分布有较严重的疏松,增加了销轴表面的脆性,使销轴表面形成了较多的微裂纹,导致了疲劳裂纹的萌生;销轴的渗氮层深度和硬度偏低也降低了销轴的疲劳强度,加速了疲劳裂纹的扩展,最终使销轴发生早期疲劳断裂。     

飞机操纵系统链条销轴断裂分析

某型飞机操纵系统链条销轴在使用中断裂。采用化学成分分析、外观检查、断口分析和表面质量检验等方法对断裂销轴进行了分析,又对有裂纹的销轴与断裂销轴进行了对比分析。结果表明：销轴表面存在原始缺陷,加上链条链板在长期使用中的磨损使得链板间隙增大,导致销轴承受剪切力的同时又承受弯曲载荷,最终导致销轴发生疲劳断裂。     

550kV断路器操作机构轴销的断裂原因分析

在断路器1 000~2 000次机械操作试验中,30CrNi3合金钢渗氮轴销发生断裂。通过化学成分分析、断口分析、低倍检验、金相检验、力学性能测试的方法,对轴销的断裂原因进行了分析。结果表明:该轴销的断裂性质为双向弯曲疲劳断裂;轴销材料渗氮层存在脉状氮化物,内部存在疏松、大尺寸夹杂物和气泡缺陷,降低了材料的力学性能;在周期性旋转弯曲力作用下,轴销表面缺陷处出现裂纹并不断扩展,最终导致轴销疲劳断裂。     

万向轴十字销断裂原因

某万向轴十字销在机车运行过程中发生断裂,采用宏观观察、化学成分分析、硬度测试、金相检验、扫描电镜分析等方法对其断裂原因进行了分析。结果表明：不良的淬火马氏体组织及大尺寸的MnS夹杂降低了十字销倒角部位的抗疲劳性能,在交变应力的作用下,十字销发生疲劳断裂。     

45B钢链轨销轴断裂原因分析

某45B钢链轨销轴在使用过程中发生早期断裂。通过化学成分分析、硬度测试、有效硬化层深度测定、金相检验、断口分析等方法,对销轴的断裂原因进行了分析。结果表明:销轴断裂机制为准解理断裂+韧性断裂的混合型断裂;在使用过程中,45B钢材料中的球状氧化物剥落留下微孔洞形成裂纹源,在弯曲应力的作用下,裂纹源迅速放射扩展,造成销轴早期断裂。     

减速机轴断裂分析

某减速机使用30多小时后，齿轮减速机轴发生弯曲，该轴在进行冷校直时发生断裂。通过对断裂轴的断口宏微观分析、金相检验以及硬度测定，认为该轴是在应力集中条件下承受对称旋转弯曲载荷作用，产生早期疲劳断裂。造成疲劳断裂的原因是由于热处理工艺不合理，致使材料力学性能未达到设计要求，导致轴的疲劳抗力降低，加之圆角加工较差，工作时产生应力集中，加速了轴的疲劳断裂。     

内燃机车活塞销断裂分析

本文通过对断裂的活塞销进行宏观检验、化学分析、金相检验、SEM分析、硬度检测及受力情况的分析,找到了活塞销发生断裂的原因,即活塞销设计思想有误,并且在淬火时温度偏低或保温时间较短,致使组织中出现大量铁素体,降低了活塞销的疲劳强度,另外,活塞销油槽、油孔加工时较粗糙,在应力的作用下发生了疲劳断裂。     

蒸发器管子管板液压胀芯轴断裂分析

某公司在进行蒸发器管子管板液压胀管过程中,胀管芯轴多次发生断裂,采用光学显微镜、扫描电子显微镜、拉伸试验机和直读光谱仪等设备对芯轴的断裂原因进行了分析。结果表明：由于液压胀过程中固定工装仅一侧固定,从而容易在芯轴螺栓螺纹根部形成应力集中,引发低周疲劳,造成芯轴疲劳断裂,缩短芯轴的使用寿命。最后对芯轴液压胀工艺提出了建议。     

变速箱二轴的断裂分析

汽车变速箱二轴在工作中发生多起断裂事故。采用金相检验、扫描电镜和化学成分分析等手段，对断裂变速箱二轴进行了检验分析。结果表明，轴的断口具有明显的疲劳特征，疲劳源位于二轴花键槽根部。由于渗碳淬火工艺不当，在二轴花键槽根部的组织中产生了网状碳化物和粗大的针状马氏体，在外力作用下形成沿晶显微裂纹并扩展，是导致二轴疲劳断裂的主要原因。     

钻机刹车盘销轴失效分析

石油钻机刹车盘销轴在工作过程中断裂。采用化学成分和宏、微观分析等方法对断裂件进行了分析,结果表明,热处理不当和材料原始组织中存在大量氧化夹杂物而造成材料强韧性不够,最终造成在使用中销轴发生断裂。     

Stress and failure analysis of the crankshaft of diesel engine

In this work the failure analysis of the crankshaft of diesel engine was performed. Visual examination of the crankshaft fracture showed that beach marks, typical for fatigue failure were observed. Additional observations of the crack initiation zone indicated that crack origin was not covered by material defects or corrosion products. Performed hardness test of the fractured crank pin showed that large HRC values were observed in central part of the pin only. On the corner of cylindrical pin surface where the crack origin was located the hardness of material was much smaller. In order to explain the reason of premature crankshaft damage, the finite element method was utilized. The results of nonlinear static analysis showed that during work of the engine with maximum power the high stress area was located in crack initiation zone. Based on results of performed investigations it was concluded that the main reason of premature fatigue failure was high-cycle fatigue of the material in external zone of the crank pin where the small structural radius was designed. In final part of the work the recommendations for increase of the fatigue life of analyzed crankshaft were formulated.     

游梁式抽油机曲柄销的故障树分析

介绍了利用故障树分析事故原因的方法,以游梁式抽油机曲柄销故障现象为例建立故障树,通过求解最小剖集对实际故障进行定性分析,提出提高曲柄销疲劳强度和寿命的方法。     

Research on the influences of torsional deformation on contour precision of the crank pin

The span and length to diameter ratio of the large-scale crankshaft are big,and the structure and the distribution of crank pins are complex.Thus it is easier for crankshaft to generate biggish torsional deflection which finally influences the contour precision of the crank pin in tangential point tracing grinding.Based on the analyses of force and torsional deformation of the crankshaft under different crankshaft driving modes of the headstock and the tailstock,the relationship between torsional deformation and rotation angle error of the crankshaft in tangential point tracing grinding is discussed in this paper.According to crankshaft rotational motion and wheel frame coordinated motion in tangential point tracing grinding,contour error of the crank pin caused by torsional deflection is established under different crankshaft driving modes.The simulation results show that minimum contour error of the crank pin can be obtained when crankshaft is synchronously driven by both the headstock and the tailstock,and speed error does not exist in tangential point tracing grinding.     

屋顶盒包装机顶封曲臂的优化设计

目的对屋顶盒包装机的顶部封口机构曲臂进行优化设计。方法首先,通过ADAMS求解初始曲臂在工作时的极限载荷,利用Hyper Works中Opti Struct模块对初始曲臂进行准静态分析,得到模型应力云图与位移云图,根据分析结果确定基于相对密度法的结构优化模型。然后,应用Opti Struct创建以最小体积为目标函数的全局响应,以最大应力和最大位移为约束条件的、与子工况相关的响应,从而进行拓扑优化。最后,利用ABAQUS对优化后的模型和连接件进行非线性有限元分析校核。结果优化后模型的质量减少了0.67 kg,最大应力值为48.71 MPa,位移最大值为0.04 mm。结论对封口机构曲臂进行拓扑优化设计可行,不仅可以减少质量成本,也能满足结构的刚强度要求。     

Study on the stress characteristic and fatigue life of the shredder pin

The hammer shredder is the key equipment for cyclic utilization of retired car bodies. The axes' pin is the main component of the shredder, but it is damaged easily. To improve the shredding efficiency and lengthen the changing life of the shredder pin, it is significant to study its stress characteristic and the fatigue life. In this article, the complex force conditions of the shredder pin at the normal working condition were studied briefly by mechanics analysis method. The stress characteristics and fatigue life of the pin were analyzed by the finite element transient analysis method. The maximum stress distribution law of the shredder pin was found and the fracture mechanism of the retired car bodies was revealed. Furthermore, the reliability of the simulation results was verified by the experiment. It was found that when the pin rotates around the main shaft counterclockwise, the maximum stress of the pin at 0° of the main shaft is higher than other positions. Additionally, along the axial direction, the maximum stress occurs at the cross section at a distance of 2/9 of the pin length from the pin head and at 0° of this section, which orientation is made when the pin is at 270° of the main shaft. Comparing four working modes, it was found that the working life of the shredder pin could be doubled by changing the sides of the pin and rotate it along its axes by 180°.     

耐特种气体腐蚀涡旋干泵的研制

采用化学镀、氟涂料和真空离子镀(PVD)技术对涡旋干泵实施防护涂层,对转子和定子采用化学镀镍磷和氟涂料封闭技术制备防护涂层;对曲柄轴和曲柄销采用PVD技术制备Cr/CrN多层复合防护镀层。通过腐蚀试验表明,防护涂层可以长时间抵抗高腐蚀性气体的腐蚀,能够有效地提高涡旋干泵的使用寿命。     

CO2涡旋压缩机动力学特性的研究

通过对动盘和十字滑环所构成的力系进行分析,建立了CO2涡旋压缩机样机的动力学模型,并采用全局牛顿法进行数值求解.在三种压缩机转速下,计算了十字滑环和曲柄销受力随主轴转角的变化规律,并给出了主要运动部件的摩擦功耗随主轴转角的变化规律.结果表明:随着转速的提高,十字滑环受到的最大作用力分别为:21.07N,25.71N和30.81N,曲柄销受到的最大作用力分别为899.89N,1045.34N和1133.51N,主轴承的耗功百分比增加.在所计算的工况范围内,动静盘间的耗功是最大的机械摩擦损失来源,占到了总摩擦损失的45％左右,其次是主轴承耗功,占到了总摩擦损失的33％左右,十字滑环的耗功所占比例非常小,仅为0.23％左右.     

汽车发动机曲轴断裂分析

某6缸发动机曲轴在运行8910km时,第六曲拐颈断裂。对断裂曲轴进行了断口观察、化学成分复验、基体硬度和显微组织检验。结果表明,曲轴的拐颈断裂为扭转疲劳断裂,断裂疲劳源位于油道孔与倒圆角曲面交接处,此处的切削加工刀痕及金属损伤形成应力集中且处于最大主应力面上,因而引发扭转疲劳断裂。     

轴销断裂事故分析

采用断口分析、金相检验及受力分析等方法,从微观机理及宏观力学两方面分析了轴销断裂的原因,并建立了力学模型考察其疲劳强度。试验结果表明,造成轴销断裂的主要原因是热处理工艺控制不当。     

Failure Analysis of a Cyclic Contact Testing Machine Pin

The goal of this paper is to investigate the failure of a mandrel pin mounted on a rolling contact test bench. For this purpose, different methods of analysis were conducted, including metallography and stress analysis. The stress values in the failed pin were determined by Finite Elements. The high notch effect and the incorrect mounting of the specimens were identified as the failure causes. A pin design change is proposed to reduce the maximum stress even in the case of incorrect specimen mounting.