节点文献

倾斜基体上的激光熔覆层形貌研究

Study on the Morphology of Laser Cladding Layer on Inclined Substrate

【作者】 李海波

【导师】 张洪潮;

【作者基本信息】 大连理工大学 , 机械设计及理论, 2017, 硕士

【摘要】 激光熔覆是一种新兴的表面改性和表面修复技术,在汽车工业、航空航天、装备制造等行业均有应用。目前很多研究都是基于激光头垂直于水平基体进行的,实际零件的形状较复杂,在修复时激光头可能会与零件产生干涉,导致修复过程无法进行。倾斜基体激光熔覆为此提供了一种解决方案。通过保持激光头垂直,将待修复表面倾斜,避免激光头与零件发生干涉。但是目前关于倾斜基体激光熔覆的研究却很少,理论体系不健全。因此倾斜基体激光熔覆的理论和试验研究尚需完善。对倾斜基体上单道单层激光熔覆层的熔深进行了研究。利用米氏散射理论建立了在倾斜基体上激光熔覆时基体表面能量分布的理论模型,并通过试验对模型进行验证。设熔深与能量密度的峰值呈正比,熔深的偏移量与能量密度的偏移量相同,理论和试验得出的规律是一致的。对倾斜基体上单道单层激光熔覆层的熔覆层形状进行了研究。用两个椭圆的一部分来表征倾斜基体上熔覆层的形状,与实际情况相吻合。通过试验研究了基体倾斜角度与熔覆层形状(熔覆层的宽度、高度、面积和偏移量)之间的关系。分析了在50°倾斜基体上进行激光熔覆时工艺参数(激光功率、送粉率和扫描速度)对熔深和偏移量的影响规律,以及对熔覆层形状和质量的影响规律。对倾斜基体上多道单层激光熔覆层的熔覆层形貌进行了研究。对比倾斜基体上四种扫描方式来观察熔覆层形貌和表面质量的不同,四种扫描方式分别为沿x轴正方向、沿y轴正方向、沿y轴负方向以及在平面基体上扫描。并提出了扫描方式的选择依据。并基于上述研究,论述了沿x轴正向自下而上扫描、沿x轴正向自上而下扫描、沿y轴正向扫描和沿y轴负向扫描四种搭接方式的特点,为实际修复奠定基础。利用倾斜基体激光熔覆的方法对预设零件进行修复。熔覆层的尺寸和表面质量满足要求。但是与待修复表面相邻和相对的表面会因为反射激光的作用而产生烧痕,反射的粉末会粘结在相邻和相对的表面上,对其表面质量和性能产生影响。因此在激光熔覆修复时需对其他表面采取保护措施。理论和试验证明,用倾斜基体激光熔覆的方法对零件进行修复是可行的。

【Abstract】 Laser cladding is an advanced surface modification and surface repair technology,whichhas been widely used in aerospace,automotive,equipment manufacturing and other fields.At present,many researches are based on the horizontal substrate,and the laser head is perpendicular to the substrate,but in the actual production process,most parts are complex,the laser head may interfere with the part.This paper provides a solution for laser cladding of inclined substrate.By inclining the surface to be repaired to avoid collision between the laser head and parts.However,the relevant research is less,the theoretical basis is not perfect.In this paper,the basic experimental research on laser cladding of inclined substrate is carried out:Firstly,the molten pool depth of laser cladding layer was studied.Based on Mie scattering theory,the theoretical model of the energy distribution on the substrate surface during laser cladding is established,and the model is verified by experiments.The depth of the weld pool is proportional to the peak value of the energy density,and the offset of the weld pool is the same as that of the energy density.Secondly,the shape of the cladding layer on the laser cladding layer was studied.The combination of two ellipses is used to represent the shape of the cladding layer on the inclined substrate.The relationship between the inclined angle of the substrate and the shape of the cladding layer(the width,the height,the area and the offset of the cladding layer)is studied.Then,the influence of laser parameters,such as laser power,powder feeding rate and scanning speed,on the depth and offset of the weld pool was studied when the laser cladding was carried out on 50 degree inclined substrate.The relationship between the morphology and quality of the cladding layer and the processing parameters on the 50 degree inclined substrate was also studied.Next,the morphology of the multichannel cladding layer on the inclined substrate was studied.The morphology and surface quality of the cladding layer were observed by four scanning methods on the inclined substrate.The four scanning modes were along the y axis direction,along the negative direction of the y axis,along the x axis direction and on the horizontal substrate.The choice of scanning direction is put forward.Based on the above research,the characteristics of the four scanning methods are studied.The four scanning mode is along the x axis scanning from the bottom up,along the x axis scanning from top to bottom,along the y axis forward scan and negative scan along the y axis,which laid the foundation for the actual repair.Lastly,repair a part by laser cladding.The size and surface quality of the cladding layer meet the requirements.However,the surface adjacent and opposite to the surface to be repaired will produce a burn mark due to the reflection of the laser.The powder can be bonded to the adjacent and opposite surfaces,which has an effect on the surface quality and properties.Therefore,the protection of other surface should be taken in laser cladding repair.It is proved by theory and experiment that it is feasible to repair the parts by laser cladding on inclined substrate.

节点文献中: 

本文链接的文献网络图示:

本文的引文网络