【作者】 杨斌；

【导师】 杨永强； 黄延禄； 黄勇；

【作者基本信息】 华南理工大学 ， 机械工程， 2011， 硕士

【摘要】 激光熔覆是一种新的材料加工与表面改性技术,该技术可以在低成本钢上制成高性能表面,代替大量的高级合金,以节约贵重、稀有的战略金属,提高材料的综合性能,实现对重大零件的快速绿色修复。经过多年的研究开发,目前,该项技术己经具有了较高的技术水平和相当的应用规模。送粉喷嘴是激光熔覆系统的关键部件之一,其对激光熔覆质量有非常重要的影响,同轴送粉喷嘴因具有送粉流各向同性并且适宜于3D熔覆的特点而成为目前研究的热点,深入开展三维同轴送粉喷嘴的研究具有重要的理论意义和实际应用价值。本课题主要是围绕载气式激光熔覆同轴送粉喷嘴的设计及制造开展的工作。首先,按照激光熔覆送粉喷嘴的功能要求,综合机械设计的相关理论知识,对其结构进行创新设计,并利用三维造型软件Pro/E绘制出了一种免装配结构的激光熔覆送粉喷嘴的参数化几何模型。设计了一个正交试验,并运用多物理场耦合分析软件Comsol Multiphysics对设计出的新型喷嘴的载粉气流进行CFD仿真。统计分析每组试验的结果,主要研究激光熔覆过程中送粉喷嘴的粉末流参数(聚焦焦距和聚焦半径)在送粉通道轴向锥角、激光出光口半径和出粉口宽度3个因素的不同水平组合下的变化规律,得出了如下两个重要结论:(1)喷嘴设计的最优尺寸组合为送粉通道与喷嘴轴向的锥角25°,激光出光口半径2.2mm,出粉口宽度1.3mm。(2)影响粉末流汇聚特性的因素的主次顺序依次为出粉口宽度、送粉通道轴向锥角、激光出光口半径。最后,利用选区激光熔化(Selective Laser Melting,SLM)的方法快速成型出经结构优化和尺寸优化的免装配激光熔覆送粉喷嘴,对其后处理以后进行了相关性能测试。更多还原

【Abstract】 Laser cladding is a new material processing and surface modification technology, the technology can be made of high-performance low-cost steel instead of a large number of advanced alloys on the material surface, in order to save precious, rare and strategic metals, improve overall performance of materials, to achieve the quick green fix of the vital parts. After years of research and development, at present, the technology has been with a high technical level and the application of considerable scale.Powder feeding nozzle is one of the key components of laser cladding system, it has significant impact on the quality of laser cladding, coaxial powder feeding nozzle has become a hot research due to the characteristics of its powder feed stream isotropic and suitable for 3D cladding, so there are important theoretical significance and practical value for depth research on three-dimensional coaxial powder feeding nozzle.The subject’s main work is carried out around the design and manufacture of carrier gas type coaxial powder feeding laser cladding nozzle. Firstly, in accordance with the functional requirements of laser cladding powder feeding nozzle, referencing to the relevant theoretical knowledge of mechanical design, innovatively designed its structure, and drawn parametric geometry model of the laser cladding powder feeding nozzle with a free assembly structure. Designed an orthogonal experiment, and did CFD simulation experiment on the airflow carrying powder of the designed new nozzle with multi-physics coupling analysis software COMSOL Multiphysics. Statistic and analyze results of each experiment, mainly research changing regularity of the powder feeding nozzle’s powder stream parameters(focal length and focus radius) in laser cladding process under the circumstance of different combinations of level of three factors(axial cone angle of powder feeding channel, radius of laser outlet and width of powder outlet), reached the following two important conclusions:(1) Optimal combination of the nozzle‘s geometry size are that and the axial cone angle of powder feeding channel is 25°, radius of laser outlet is 2.2mm and width of powder outlet is 1.3mm.(2) The primary and secondary sequence of factors which affect powder stream’s convergence properties are the width of powder outlet, the axial cone angle of powder feeding channel and the radius of laser outlet. Finally, manufactured the free assemble laser cladding powder feeding nozzle which has been optimized on structure and size with the method of Selective Laser Melting Rapid Prototyping, and carried out relevant performance test after its post-processing.更多还原