Fatigue fracture analysis of gear teeth using XFEM

Gear teeth in gear transmission systems suffer seriously from fatigue failure during service. In this work, a 2D double-tooth model was constructed with periodic boundary conditions. The fatigue fracture behavior of gear teeth was analyzed using the extended finite element method (XFEM), with emphases on the impacts of initial crack geometries and cyclic load factors. The results suggested that the shortest fatigue life is expected for 0° orientation cracks initiating at the maximum principal stress. Cracks that initiate closer to the bottom land of gear tooth are relatively safe. Moreover, to evaluate the fatigue load conditions, load ratio, load range, and mean load should be all taken into considerations. Further XFEM simulation for material selection was performed to guide the gear design. Among various material parameters, the material constant C and tensile strength are the most significant ones in determining the fatigue life.     

熔体增压泵在工程设计选型中需要考虑的几点工况

通过分析涤纶熔体直纺生产现场的常见工况对增压泵驱动功率的影响及其规律,对照多条生产线增压泵运行维护记录,分析了长周期稳定运行的条件和短期出现故障的原因,归纳总结了影响增压泵稳定运行的主要因素,并给出了相应的建议,指出了增压泵上限产量、熔体下限输送温度、纺丝箱体内部的计量泵入口下限压力是设计选型考虑的要点;同时合适的设备选型服务系数也是长周期稳定运行的必要条件。     

复杂轮系在镗孔车端面装置中的应用

本文研究复杂轮系在镗孔车端面装置中应用,分析行星轮系与差动轮系构成的并联复合轮系,行星轮系和定轴轮系组成的串联混合轮系,探讨了孔车端面装置在粗、精加工及快退时进给运动和进给量等,阐明镗孔车端面装置的应用原理。     

承钢1780线精轧机的减速机螺栓断裂分析

介绍了对承钢1780生产线F1精轧机减速机输入轴固定螺栓和F3精轧机减速机地脚螺栓断裂的断口形貌.对其最大承受力和直径进行了计算,对其微观组织进行了分析,找到了这两起螺栓断裂失效的原因,给出了相应的解决措施.     

差动轮系在翻转机构中的应用与分析

在工程实际中,为了满足各种不同传动的需求,大多数情况下,采用一系列彼此啮合的齿轮来实现传动。本文以差动轮系为例,介绍差动轮系在翻转机构的应用,并用ADAMS软件验证可行性,为以后的优化设计提供理论依据。     

Torque loss of type C40 FZG gears lubricated with wind turbine gear oils

Five fully formulated wind turbine gear oils were characterised. The gear oils have 320 ISO VG grade and different formulations: ester, mineral, PAO, PAG and mineral+PAMA.A back-to-back FZG test machine, with re-circulating power, was used and a torque-cell was included on the test rig in order to measure the torque loss. Eight thermocouples were included to monitor the temperatures in different locations of the test rig.Tests at 1.13, 2.26 and 6.79 m/s were performed for different FZG load stages: K1, K5, K7 and K9. Both gearboxes were jet-lubricated with an oil flow of 3 l/min. The input flow temperature was kept almost constant (80 ±1 °C).Friction generated between the meshing teeth, shaft seals and rolling bearing losses was predicted.     

新型锥齿轮-滚轮平盘式无级变速器摩擦效率及温度场研究

针对摩擦式无级变速器摩擦生热和温度场的研究，以自行设计的新型锥齿轮-滚轮平盘式无级变速器为例，对传动过程中的滑移率、功率损失和摩擦效率进行理论研究，并用ANSYS软件对滚轮平盘摩擦生热温度场进行仿真分析。结果表明：随着转速的提高滚轮和平盘的温度上升，随着压紧力的增大，摩擦功率损失提高，摩擦效率降低；压紧力的提高，滑动速度会随之增大，产生更多摩擦热，同时也会增大接触面积，摩擦发热的面积更大，因此对温升影响更明显；新型锥齿轮滚轮-平盘式无级变速器具有较高的摩擦效率，其摩擦升温也较小。     

Optimisation of method for reducing residual stresses after cold bar drawing

Abstract

A new method to reduce the residual stresses after cold bar drawing has been proposed and optimised. This new method addresses the disadvantages of previous methods proposed by the authors, and needs neither the use of an extra finishing die nor an intricate die geometry. The application of axial tension to the bar or wire after drawing is all that is required, and by adjusting the magnitude of the tension it is possible to control the residual stresses in the final product. Axisymmetric elastic-plastic finite element analysis was carried out to examine quantitatively the influence of tension, followed by laboratory experiments using a thick, not thin, bar for convenience of measurement of residual stresses. The optimum value of tension was then determined. The applicability of the proposed method is discussed in the present paper. The new method is especially effective when applied to high speed cold drawing of an extremely thin wire, because the tension applied to the wire after finishing can be readily controlled simply by adjusting the peripheral speed of the rollers/pulleys.     

新型立交分片机

传统分片机结构复杂,设备笨重,响应缓慢,安装和维修困难。新型立交分片机由输送结构和升降机构两部分组成,结构简单,升降灵活,响应快速,安装维修方便。其更换同步带的新结构,解决了同步带更换难题。同时,通过设置连体式曲柄连杆机构,使升降功能更加简单稳定。     

转速对齿轮泵内流场空化强度的影响

针对齿轮泵中齿轮转速在500~3652 r/min的变转速条件下工作的实际工况,该文通过实验的方法研究了转速对某型齿轮泵内流场空化强度的影响。使用现有的齿轮泵测试实验台,对在齿轮泵转速改变的条件下,齿轮泵内流场的空化强度改变进行监测。由于空化无法直接测量,该文根据空化诱导振动理论对齿轮泵的振动进行测量,得到了齿轮泵内流场空化强度随齿轮转速上升而增强的规律。通过Pumplinx软件对内流场进行建模,利用软件特有的空化损伤模块进行了仿真验证,仿真结果表明齿轮泵内流场空化强度随齿轮转速上升而增强,与实验所得规律一致。本文所总结的规律对减弱齿轮泵内流场空化强度,提升使用寿命具有一定的参考作用。