激光柔性冲击金属箔板微胀形研究

发布时间：2018-03-19 15:13

本文选题：激光柔性冲击　切入点：金属箔板　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着微型化和集成化趋势的日益突出,具有微特征零件的应用越来越广泛,推动了微成形技术的发展。其中,金属箔板微成形技术成为当前研究的热点。本文结合激光冲击微胀形技术和软模微胀形技术建立激光柔性冲击微胀形工艺。该工艺基于微胀形模具,利用激光冲击软模作为柔性冲头,实现单脉冲激光能量下金属箔板的微胀形成形。本文通过实验研究和数值模拟展开了激光柔性冲击金属箔板微胀形的性能研究,其主要研究内容和成果如下:首先,对304不锈钢箔板进行激光柔性冲击微胀形实验,研究了不同激光能量和工件厚度对微胀形件的表面形貌、深度、厚度减薄率和截面硬度分布的影响。通过SEM对微胀形件的表面形貌进行观测,发现随着工件厚度的增加和激光能量的减小,其形貌从近似球面过渡到球面;底部缺陷随着工件厚度和激光能量的增加从微裂纹发展到微层裂。通过基恩士VHX-1000C超景深三维显微镜对微胀形件的深度和厚度进行测量,结果表明:随着工件厚度的减小和激光能量的增加,深度和厚度减薄率均增加。通过纳米压痕仪对微胀形件截面的硬度进行测试,发现不同胀形区域的硬度均有一定的提高。通过TEM观测胀形区域的微观组织,发现经过激光柔性冲击后的材料内部出现晶粒细化现象。然后,进行了激光柔性冲击铜箔微胀形的尺寸效应实验,研究了晶粒尺寸和模具特征尺寸对材料变形行为的影响。通过基恩士VHX-1000C超景深三维显微镜对微胀形件的胀形深度进行检测,结果表明:胀形深度以及其变形不均匀性随着晶粒尺寸和模具特征尺寸的增加而增加。通过Axio CSM700真彩色共聚焦显微镜对微胀形件的表面质量进行观测,发现微胀形件的表面粗化程度随着晶粒尺寸的增大而增加;随着模具特征尺寸的增加,表面粗化程度先增加后减小。通过测量微胀形件的厚度发现:随着晶粒尺寸的增加,底部厚度越小,且胀形件截面塑性变形不均匀性增加。随着模具特征尺寸增加,截面厚度变化明显,尤其从模具1变化到模具2;而从模具2变化到模具3,其厚度变化相似。最后,利用ANSYS/LS-DYNA和LS-PREPOST软件模拟分析了不同激光能量、不同厚度的304不锈钢箔板的激光柔性冲击微胀形成形,研究了激光柔性冲击加载下金属箔板的微胀形历程和不同参数对材料微塑性变形规律的影响。揭示了激光柔性冲击金属箔板微胀形成形两个阶段:弯曲阶段和胀形阶段。模拟分析了箔板微胀形的深度、厚度减薄率、工件的弹塑性响应速度和等效应力与等效塑性应变分布,其中胀形深度和厚度减薄率的变化趋势与实验结果一致。
[Abstract]:With the increasing trend of miniaturization and integration, the application of micro-feature parts is becoming more and more extensive, which promotes the development of micro-forming technology. The technology of metal foil sheet microforming has become a hot research topic at present. In this paper, the laser flexible impact micro-bulging process is established by combining laser impact micro-bulging technology with soft mode micro-bulging technology. This process is based on micro-bulging die. The micro bulging of metal foil plate under single pulse laser energy is realized by using the soft mode of laser shock as the flexible punch. In this paper, the performance of the micro bulging of metal foil plate is studied by means of experimental research and numerical simulation. The main research contents and results are as follows: firstly, the laser flexible impact microbulging experiments are carried out on 304 stainless steel foil plates, and the surface morphology and depth of micro-bulging parts with different laser energy and workpiece thickness are studied. The influence of thickness thinning rate and cross section hardness distribution. The surface morphology of micro-bulging parts was observed by SEM. It was found that the morphology of micro-bulging parts transitioned from approximate spherical surface to spherical surface with the increase of workpiece thickness and the decrease of laser energy. The bottom defect develops from microcrack to microspallation with the increase of workpiece thickness and laser energy. The depth and thickness of microbulging parts are measured by using Keenz VHX-1000C hyperfield 3D microscope. The results show that with the decrease of workpiece thickness and the increase of laser energy, the depth and thickness thinning rate increase. It is found that the hardness of different bulging regions has been improved to a certain extent. By observing the microstructure of bulging region by TEM, it is found that there is a grain refinement phenomenon in the material after flexible laser impact. The effects of grain size and die characteristic size on the deformation behavior of copper foil were studied by the size effect experiment of laser flexible impact copper foil. The depth of bulging of micro-bulging parts was measured by using Keenz VHX-1000C superfield depth three-dimensional microscope. The results show that the depth of bulging and the inhomogeneity of deformation increase with the increase of grain size and die characteristic size. The surface quality of micro-bulging parts is observed by Axio CSM700 true color confocal microscope. It is found that the surface coarsening degree of micro bulging parts increases with the increase of grain size, and increases first and then decreases with the increase of die characteristic size. By measuring the thickness of micro bulging parts, it is found that: with the increase of grain size, The smaller the bottom thickness is, the more inhomogeneous plastic deformation of the bulging parts is. With the increase of the characteristic size of die, the thickness of the bulging parts changes obviously. Especially from mold 1 to die 2, and from mold 2 to mold 3, the thickness change is similar. Finally, the soft impact of 304 stainless steel foil with different laser energy and thickness is simulated and analyzed by ANSYS/LS-DYNA and LS-PREPOST software. The microbulging history of metal foil plate under laser flexible impact loading and the influence of different parameters on the microplastic deformation of materials are studied. The two stages of micro-bulging formation of metal foil plate under laser flexible impact loading are revealed: bending stage and expanding stage. The depth of microbulging of foil plate is simulated and analyzed. The thickness thinning rate, the elastic-plastic response velocity and equivalent stress and the equivalent plastic strain distribution of the workpiece are in good agreement with the experimental results.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665

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