【作者】 贾瑞燕；

【导师】 张广军；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2011， 硕士

【摘要】 钩舌是火车车钩缓冲装置的重要部件之一，长期使用导致钩舌S面产生严重磨损、裂纹，甚至报废。对钩舌磨损件进行基于GMAW(Gas Metal ArcWelding)的再制造修复，研究该过程残余应力、变形规律，优化堆积路径，对于提高钩舌修复质量，具有重要意义。本文研究了13A型货车钩舌在典型再制造修复路径下的温度场、应力、变形规律，并通过对不同堆积路径下堆积热过程、应力变形进行对比分析，以优化钩舌修复路径。本文采用有限元MSC.Marc软件，建立钩舌修复的热-应力直接耦合计算模型。针对工件体积大、结构复杂、网格单元数目庞大、材料性能参数随温度非线性变化、求解收敛困难、边界条件复杂、计算时间过长等问题，采用生死单元法按堆积顺序逐步激活填充金属网格，利用定义接触体法有效减少网格总数，提高了计算速度。通过验证实验，实测了钩舌修复过程典型位置热循环以及残余应力分布，对比得出，模拟与实测结果基本吻合，验证了模型正确性。以沿长边由内到外反向连续堆积修复过程为例揭示温度场、应力场的一般分布规律，并对残余应力和变形分布特点进行探讨。结果表明：钩舌堆积修复过程，前道对后道有预热作用，后道对前道有后热作用，且随堆积道数增加热积累作用增大；后道热过程可使前道得到部分应力释放；残余应力分布为：在S面拘束度较大的内凹面区域应力较大，外凸面区域应力较小，末道堆积区域出现局部应力最大值。分析对比不同堆积路径对修复热过程、残余应力、变形的影响，结果表明：从温度场角度分析，沿长边由外向内堆积比沿长边由内向外堆积更有利于散热；沿短边堆积温度场分布最不平均；从应力场角度分析，在钩舌S面内弯角处，短道正、反向两种修复过程残余应力最小，其次是沿长边由外向内堆积的两种方式，最后是沿长边由内向外堆积的两种方式；从变形角度分析，每种修复方式均符合要求。根据上述结果，采用优化的路径进行堆积修复，道间等待20s，可以有效的降低S面内弯角处应力，以减少疲劳裂纹产生的可能性，提高修复质量。更多还原

【Abstract】 Coupler knuckle is an important component of the buffer device for traincoupler. Long-term use will cause the serious wear cracks or even scrapping onthe S-surface of coupler knuckle. Therefore it’s practically useful to repair worncoupler knuckles by GMAW-based remanufacturing technology, and study thestress, deformation process and optimize the depositing path to improve therepair quality. In this paper, the thermal process, stress and deformation in theremanufactuing process of coupler knuckle (13A type) with the typicaldepositing path are studied, and the depositing path is optimized by analyzingthe thermal process, stress and deformation in different depositing processeswith different depositing paths.The thermal-mechanical coupled finite element models of repairing thecoupler knuckles were prensented using the software Msc.Marc. Due to theproblems, such as large dimensions, complex structure, large number of elements,nonlinear variation of material properties with different temperatures, difficultyin the convergence of calculation, intricate boundary conditions, the longcalculated time and so on, the life and death element method was adopted toactivate elements along the depositing paths gradually, and the contact bodieswere used to effectively decrease total number of elements and improvecalculation speed. Meanwhile, the verified experiments were carried out, and thethermal cycles and residual stresses at typical locations were measured. Aftercomparison, simulation results agreed with experiments, verifing the modelcreated.Distribution rules of the temperature and stress filed in the remanufacturingprocess along the long edges from inside to outside was revealed, and theresidual stress distribution and deformation was studied. Results reveal thatformer pass has preheating effect on later passes, and the later pass has postheatingeffect on former pass. Thermal accumulation effect increased with thenumber increase of the depositing pass. Besides, post-heating effect can releasesome stress of former passes. The residual stress is larger in the concave face ofS-surface, where the restraint is higher, than that in the convex face. And thelocal maximum stress appears in the depositing region of the last pass.After comparing the effects of different cladding paths on the thermalprocess, residual stress and deformation, conclusions are drawn as follows: Fromthe view of temperature distribution, the depositing path along long edges fromoutside to inside is better for cooling down of S-surface than that from inside to outside, and the depositing path along the short edges is the worst. From the viewof stress field distribution, the local high stress distributes in the region aroundthe last pass. In the critical region of S surface of the coupler knuckle, thedeposing path along short edges show the least traverse residual stress, and thatalong the long edges from outside to inside is better than that along the longedges from inside to outside. From the view of the deformation, all depositingprocesses meet with deformation requirement. The above results suggest themost appropriate remanufacturing path. That is the depositing path along thelong edges from outside to inside, with a waiting time 20s between adjacentdepositing. With this depositing path, it’s effective to avoid large stressconcentration at the inside corner of S-surface, reduce the probability of fatiguecracks and improve remanufacturing quality.更多还原