本文選題：激光柔性沖擊　切入點：金屬箔板　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著微型化和集成化趨勢的日益突出,具有微特征零件的應(yīng)用越來越廣泛,推動了微成形技術(shù)的發(fā)展。其中,金屬箔板微成形技術(shù)成為當(dāng)前研究的熱點。本文結(jié)合激光沖擊微脹形技術(shù)和軟模微脹形技術(shù)建立激光柔性沖擊微脹形工藝。該工藝基于微脹形模具,利用激光沖擊軟模作為柔性沖頭,實現(xiàn)單脈沖激光能量下金屬箔板的微脹形成形。本文通過實驗研究和數(shù)值模擬展開了激光柔性沖擊金屬箔板微脹形的性能研究,其主要研究內(nèi)容和成果如下:首先,對304不銹鋼箔板進行激光柔性沖擊微脹形實驗,研究了不同激光能量和工件厚度對微脹形件的表面形貌、深度、厚度減薄率和截面硬度分布的影響。通過SEM對微脹形件的表面形貌進行觀測,發(fā)現(xiàn)隨著工件厚度的增加和激光能量的減小,其形貌從近似球面過渡到球面;底部缺陷隨著工件厚度和激光能量的增加從微裂紋發(fā)展到微層裂。通過基恩士VHX-1000C超景深三維顯微鏡對微脹形件的深度和厚度進行測量,結(jié)果表明:隨著工件厚度的減小和激光能量的增加,深度和厚度減薄率均增加。通過納米壓痕儀對微脹形件截面的硬度進行測試,發(fā)現(xiàn)不同脹形區(qū)域的硬度均有一定的提高。通過TEM觀測脹形區(qū)域的微觀組織,發(fā)現(xiàn)經(jīng)過激光柔性沖擊后的材料內(nèi)部出現(xiàn)晶粒細化現(xiàn)象。然后,進行了激光柔性沖擊銅箔微脹形的尺寸效應(yīng)實驗,研究了晶粒尺寸和模具特征尺寸對材料變形行為的影響。通過基恩士VHX-1000C超景深三維顯微鏡對微脹形件的脹形深度進行檢測,結(jié)果表明:脹形深度以及其變形不均勻性隨著晶粒尺寸和模具特征尺寸的增加而增加。通過Axio CSM700真彩色共聚焦顯微鏡對微脹形件的表面質(zhì)量進行觀測,發(fā)現(xiàn)微脹形件的表面粗化程度隨著晶粒尺寸的增大而增加;隨著模具特征尺寸的增加,表面粗化程度先增加后減小。通過測量微脹形件的厚度發(fā)現(xiàn):隨著晶粒尺寸的增加,底部厚度越小,且脹形件截面塑性變形不均勻性增加。隨著模具特征尺寸增加,截面厚度變化明顯,尤其從模具1變化到模具2;而從模具2變化到模具3,其厚度變化相似。最后,利用ANSYS/LS-DYNA和LS-PREPOST軟件模擬分析了不同激光能量、不同厚度的304不銹鋼箔板的激光柔性沖擊微脹形成形,研究了激光柔性沖擊加載下金屬箔板的微脹形歷程和不同參數(shù)對材料微塑性變形規(guī)律的影響。揭示了激光柔性沖擊金屬箔板微脹形成形兩個階段:彎曲階段和脹形階段。模擬分析了箔板微脹形的深度、厚度減薄率、工件的彈塑性響應(yīng)速度和等效應(yīng)力與等效塑性應(yīng)變分布,其中脹形深度和厚度減薄率的變化趨勢與實驗結(jié)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.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG665

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