摘要
【目的】针对某型号塑料挤出机输入轴高速挡离合器齿轮发生多齿断裂的问题,探究其失效机制,明确断裂原因,为齿轮结构改进与寿命提升提供依据。【方法】首先,通过宏观断口形貌分析与扫描电镜表征,观察断口疲劳台阶、疲劳辉纹及齿面塑性挤压/滑移痕迹,初步判定失效形式;其次,开展化学成分检测与硬度测试,验证齿轮材料的成分合规性,测试齿面与芯部硬度以判断是否经表面强化处理;然后,采用有限元法建立齿轮副模型,模拟正常配合、中心线不平行及中心线不对中3种工况,分析齿根应力分布规律,重点量化中心线不对中对齿根应力幅值的影响;最后,进行轴系弯曲刚度校核,通过计算轴的当量直径、惯性矩及齿轮处挠度,验证轴刚度不足对齿轮副中心线对中性的影响。【结果】齿轮失效形式为疲劳断裂,断口可见明显疲劳辉纹与疲劳源区;轴弯曲刚度不足导致齿轮处轴挠度超过许用挠度,引发齿轮副中心线不对中;平动自由度Y方向0.01 mm位移时,内、外齿轮齿根应力幅值分别达62.66、62.72 MPa,加速了疲劳裂纹萌生与扩展;齿轮表面未进行渗碳等强化处理,进一步降低了抗疲劳性能。
[Objective]Aiming at the multi-tooth fracture problem of the high-speed clutch gear on the input shaft of a certain type of plastic extruder,the failure mechanism was explored,the fracture cause was clarified,and a basis was provided for gear structure improvement and service life enhancement.[Methods]Firstly,through macroscopic fracture morphology analysis and scanning electron microscope(SEM)characterization,the fatigue steps,fatigue striations on the fracture,and plastic extrusion/slip marks on the tooth surface were observed,and the failure mode was initially determined.Secondly,chemical composition detection and hardness testing were carried out to verify the compliance of the gear material composition,and the hardness of the tooth surface and core was tested to determine whether surface strengthening treatment had been performed.Then,the finite element method was used to establish a gear pair model,and three working conditions(normal fit,non-parallel centerlines,and misaligned centerlines)were simulated to analyze the stress distribution law of the tooth root,with emphasis on quantifying the influence of centerline misalignment on the tooth root stress amplitude.Finally,the bending stiffness check of the shafting was conducted,and the influence of insufficient shaft stiffness on the alignment of the gear pair centerlines was verified by calculating the equivalent diameter,moment of inertia of the shaft,and deflection at the gear.[Results]The gear failure mode is fatigue fracture,with obvious fatigue striations and fatigue source areas visible on the fracture.Insufficient bending stiffness of the shaft causes the shaft deflection at the gear to exceed the allowable deflection,leading to misalignment of the gear pair centerlines.When the displacement in the Y direction of the translational degree-of-freedom is 0.01 mm,the stress amplitudes at the tooth roots of the internal and external gears reache 62.66 MPa and 62.72 MPa respectively,which accelerate the initiation and propagation of fatigue cracks.No strengthening treatment such as carburizing is performed on the gear surface,which further reduce the fatigue resistance.
作者
马根
钟继如
关凯书
MA Gen;ZHONG Jiru;GUAN Kaishu(School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China)
出处
《机械传动》
北大核心
2026年第3期187-192,共6页
Journal of Mechanical Transmission
关键词
塑料挤出机
齿轮
疲劳断裂
失效分析
Plastic extruder
Gear
Fatigue fracture
Failure analysis
