工程机械轴类零件失效分析及其热喷涂再制造工艺研究

发布时间：2018-04-18 07:34

本文选题：工程机械 + 热喷涂　；参考：《天津大学》2012年硕士论文

【摘要】：由于资源的日益短缺，产品利润空间的不断压缩，以及潜在巨大市场的刺激，再制造成为工程机械行业的一个必然趋势。热喷涂技术作为一种高效便捷的表面修复技术，有望在工程机械再制造过程中得以广泛地应用。本文以装载机变速箱二轴、三轴及驱动桥十字轴为例，，研究了工程机械轴类零件的失效机理。研究结果表明，工程机械轴类零件的主要失效方式为磨损失效，其磨损过程可以分为摩擦磨损－磨粒磨损－粘着及疲劳磨损三个阶段。磨粒磨损过程中的硬质磨粒是由摩擦磨损过程中产生的磨屑在工件进一步运行的过程中逐渐形成的，硬质磨粒的形成大大加速了工件的磨损失效过程。采用含有亚微米级WC颗粒的WC-12Co粉末，对装载机变速箱齿轮二轴、三轴及驱动桥十字轴进行了HVOF再制造。采用的参数为：C_3H_8（0.75MPa，25L/min）、O（20.75MPa，250L/min）、N（20.6MPa，13L/min，2r/min）、喷管（150mm）、喷涂距离（265mm）。通过XRD、SEM、显微硬度计等测试手段，对再制造涂层的表面质量进行了综合评定，结果表明涂层主要由WC相与Co相组成，同时含有少量的W_2C；涂层的显微硬度为1107HV_(0.1)；孔隙率为2.2%；涂层的平均抗拉强度为68.12MPa，最高达75.82MPa；涂层的主要断裂机制为沿晶断裂。为了降低热喷涂再制造成本，研发新的耐磨涂层，采用大气等离子喷涂技术（APS），探索了碳纳米管增强铁基非晶合金复合涂层的制备工艺，并通过对扁平粒子和涂层断面形貌的分析，研究了涂层的微观结构。结果表明碳纳米管的加入，可以通过“桥连”和“拔出”机制，对铁基非晶合金涂层进行强化和韧化。但由于碳纳米管的润湿性比较差，致使其与铁基非晶合金之间的结合不够充分；同时等离子喷涂过程中，碳纳米管的烧蚀比较严重，降低了碳纳米管的纤维增强作用，因此还有待进一步的研究。为了解决工程机械轴类零件表面的局部修复难题，对热喷涂的工装系统进行了再制造性设计，发明了一种热喷涂再制造工装及其自动修复控制系统，可以现实工程机械轴类零件局部表面精确、自动的热喷涂再制造过程。
[Abstract]:Due to the increasingly shortage of resources, the continuous compression of product profit space and the stimulation of potential huge market, remanufacturing has become an inevitable trend in the construction machinery industry.As an efficient and convenient surface repair technology, thermal spraying technology is expected to be widely used in the remanufacturing process of construction machinery.In this paper, the failure mechanism of shaft parts of construction machinery is studied by taking two shafts, three shafts and drive axle cross shafts of loader gearbox as examples.The results show that the main failure mode of shaft parts of construction machinery is wear failure, and the wear process can be divided into three stages: friction and wear, abrasive wear, adhesion and fatigue wear.The hard abrasive particles in the process of abrasive wear are formed gradually during the further operation of the workpiece, and the formation of the hard abrasive particles greatly accelerates the wear failure process of the workpiece.The WC-12Co powder containing submicron WC particles was used to remanufacture the two shafts, three shafts and the drive axle cross shafts of the gearbox gears of the loader.The parameters used are: 10% C3HS 8 / 0.75 MPa / 25L / min / min / min / min / 0. 75 MPA / 250 L / min / min / / min / min / 0. 6 MPA / 13L / min / 2 r / min / min, 150 mm / min nozzle, and a spray distance of 265mm / min.The surface quality of the remanufactured coating was evaluated by means of XRDX SEM and microhardness tester. The results show that the coating is mainly composed of WC phase and Co phase.The coating contains a small amount of W2C; the microhardness of the coating is 1107 HVS 0.1; the porosity is 2.2; the average tensile strength of the coating is 68.12 MPA and the maximum is 75.82 MPA; the main fracture mechanism of the coating is intergranular fracture.In order to reduce the cost of thermal spray remanufacture, a new wear-resistant coating was developed. The preparation process of carbon nanotube reinforced Fe-based amorphous alloy composite coating was investigated by using atmospheric plasma spraying technique.The microstructure of the coating was studied by analyzing the morphology of the flat particles and the section of the coating.The results show that the Fe-based amorphous alloy coatings can be strengthened and toughened by the addition of carbon nanotubes through the mechanisms of "bridging" and "pulling out".However, because of the poor wettability of carbon nanotubes, the bonding between carbon nanotubes and Fe-based amorphous alloys is not sufficient, and the ablation of carbon nanotubes is serious during plasma spraying, which reduces the fiber reinforcement of carbon nanotubes.Therefore, further research remains to be done.In order to solve the problem of local repair of shaft parts of construction machinery, the remanufacturing design of thermal spraying equipment system was carried out, and a thermal spraying remanufacturing tool and its automatic repair control system were invented.The local surface of shaft parts of construction machinery can be accurately and automatically remanufactured by thermal spraying.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH16

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