零件修复中非垂直激光熔覆形貌预测与基础研究

发布时间：2018-03-09 18:26

本文选题：非垂直激光熔覆　切入点：基础研究　出处：《新疆大学》2017年硕士论文　论文类型：学位论文

【摘要】：激光熔覆技术是实现零件修复再制造的重要方法,其独特的工艺原理,广泛的应用领域,使其在近几十年里备受研究者的青睐。由于受到熔覆设备尺寸的限制,对于有些复杂零件不能实现激光束垂直照射基体,激光熔覆时激光束照射在基体上的光斑形状发生改变,导致其和基体、粉末的耦合发生变化,熔覆条件也发生改变。因此非垂直激光熔覆不能简单套用激光垂直照射熔覆的研究成果。针对这一问题,对激光熔覆进行了基础性研究,并借助激光熔覆温度场数值模拟研究了非垂直激光照射下熔覆层的几何形貌与激光入射角的关系。在研究垂直激光照射熔覆原理的基础上,并根据非垂直激光熔覆特点程总结出物理模型,介绍了光、粉以及基体的耦合过程,为零件修复中非垂直激光熔覆形貌预测做准备。针对零件修复中非垂直激光熔覆物理过程的特点采用“生死”单元技术,利用三维瞬态温度场的数值模拟实现熔覆层的自动拟合,预测出激光束在0°、10°、20°、30°、40°入射角度熔覆层的三维几何形貌。为了验证数值模拟结果的准确性,保证其他工艺参数不变的情况下,采用实际实验对应角度下熔覆层的实际轮廓,并利用电镜扫描对获得的不用入射角度下的熔覆层图片进行宽度、高度测量、润湿角测量,结果显示:熔覆层的宽度随着激光束的入射角度增大而增加,熔覆层的高度随着激光入射角度的增大而降低,熔覆层的润湿角也随着激光束的入射角度增大而增加,这一结果与预测结果十分接近。为了进一步研究熔覆层的质量,对熔覆层进行了显微硬度测量,测量结果显示熔覆层的硬度高于基体的硬度值,熔覆层底部的硬度高于顶部的硬度值。最后针对企业的加工需求进行了内孔零件非垂直激光熔覆,熔覆结果与研究结果吻合,表明本研究的可行性。
[Abstract]:Laser cladding technology is an important method to realize part repair and remanufacture. Its unique technology principle and wide application field make it popular with researchers in recent decades. Due to the limitation of cladding equipment size, laser cladding technology is very popular in recent decades. For some complicated parts, the laser beam can not be used vertically to irradiate the matrix, and the shape of the laser beam on the substrate changes when the laser cladding, which results in the coupling between the laser beam and the matrix and the powder. The conditions of cladding have also changed. Therefore, the research results of laser vertical irradiation cladding can not be simply applied in non-vertical laser cladding. In view of this problem, the basic research on laser cladding is carried out. Based on the numerical simulation of the temperature field of laser cladding, the relationship between the geometrical morphology of the cladding layer and the laser incident angle under non-vertical laser irradiation is studied. According to the characteristic path of nonvertical laser cladding, the physical model is summarized, and the coupling process of light, powder and matrix is introduced. In order to prepare for the prediction of non-vertical laser cladding morphology in parts repair, the "birth and death" element technique is used to solve the physical process of non-vertical laser cladding. In order to verify the accuracy of the numerical simulation results, the 3D geometric morphology of the cladding layer is predicted by using the numerical simulation of 3D transient temperature field, and the laser beam is predicted at 0 掳/ 10 掳/ 20 掳/ 20 掳/ 30 掳/ 40 掳angle of incidence for the purpose of verifying the accuracy of the numerical simulation results. Under the condition that other technological parameters are not changed, the actual profile of the cladding layer under the corresponding angle of the actual experiment is adopted, and the width, height and wetting angle of the cladding layer obtained without incident angle are measured by scanning electron microscope. The results show that the width of the cladding layer increases with the increase of the incidence angle of the laser beam, the height of the cladding layer decreases with the increase of the incidence angle of the laser beam, and the wetting angle of the cladding layer increases with the increase of the incidence angle of the laser beam. In order to further study the quality of the cladding, the microhardness of the cladding is measured. The results show that the hardness of the cladding is higher than that of the matrix. The hardness at the bottom of the cladding layer is higher than the hardness value at the top. Finally, the non-vertical laser cladding of the inner hole parts is carried out according to the processing demand of the enterprise. The cladding results agree with the results of the study, which indicates the feasibility of this study.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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