激光辅助水射流微细加工氮化硅陶瓷的去除机理与工艺研究

发布时间：2018-02-13 10:25

本文关键词： 激光辅助水射流氮化硅陶瓷材料去除机理微细铣削预测模型　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：激光辅助水射流微细加工技术综合了激光无切削力、无污染和水射流无热损伤、加工范围广的优点。为了研究激光辅助水射流加工氮化硅陶瓷的性能和拓展该技术的应用范围,本论文研究了激光辅助水射流微细加工氮化硅陶瓷的去除机理及工艺。实验研究了激光辅助水射流加工工艺参数对微细切槽性能的影响。揭示了工件原始表面形貌对激光辅助水射流加工表面形貌的影响和材料去除机理。建立了激光辅助水射流微细铣削氮化硅陶瓷的槽深和表面粗糙度的预测模型。构建了基于BP神经网络的激光辅助水射流微细铣削氮化硅陶瓷微结构尺寸的预测模型。研究了激光烧蚀、水辅助激光和激光辅助水射流等技术加工氮化硅陶瓷时的加工性能,探讨了工艺参数对槽宽和槽深、表面粗糙度和热影响区宽度的影响。结果表明,激光辅助水射流加工技术能获得具有较大深宽比的槽形,其热损伤小于激光烧蚀和水辅助激光加工的热损伤。水射流压力对槽宽和热影响区宽度的影响最显著,激光脉冲能量对槽深的影响最显著,水射流冲击角度对表面粗糙度的影响最显著。研究了工件原始表面形貌对加工表面成形情况的影响。结果表明,加工氮化硅陶瓷的加工区存在热解区、氧化损伤区和软化变形区。工件原始表面的加工纹理不利于改善表面加工质量,在原始光滑表面上形成的热影响区小于在原始粗糙表面上形成的热影响区。研究了激光辅助水射流加工氮化硅陶瓷时的材料去除机理。结果表明,激光辅助水射流加工氮化硅陶瓷的材料去除机理是水射流冲击去除被激光加热软化的材料和激光照射核心区热解的材料。建立了槽深和表面粗糙度的预测模型,该模型的预测结果与实验结果基本吻合,误差较小。研究了工艺参数的交互作用对槽深和表面粗糙度的影响。横向偏置距离对槽深影响不显著,但对加工表面粗糙度影响显著;激光脉冲能量对槽深的影响最显著;水射流压力对表面粗糙度的影响最显著。激光脉冲能量与水射流压力的交互作用对槽深和表面粗糙度的影响最显著。实验证明激光辅助水射流微细加工技术微细铣削氮化硅陶瓷的微结构和微结构阵列是可行的。单个微槽的边界线平直完整,没有出现崩边和边缘热损伤。微槽阵列分布均匀,相邻微槽之间没有干涉。建立了基于BP人工神经网络的微结构尺寸预测模型,并进行了实验验证。结果表明,预测值和实验值之间具有较好的一致性,整体预测平均误差小于10%。
[Abstract]:The laser-assisted water jet micro-machining technology has the advantages of no cutting force, no pollution, no heat damage and wide range of processing. In order to study the properties of laser assisted water jet machining silicon nitride ceramics and expand its application scope, In this paper, the removal mechanism and process of laser assisted water jet micromachining of silicon nitride ceramics are studied. The effect of laser assisted water jet processing parameters on the performance of the micro-groove is experimentally studied. The original surface shape of the workpiece is revealed. Effect of appearance on surface morphology and material removal mechanism of laser assisted water jet machining. A prediction model of groove depth and surface roughness for laser assisted water jet micro-milling of silicon nitride ceramics was established, and a BP neural network was constructed. The prediction model of microstructural size of silicon nitride ceramics by laser-assisted water jet micro-milling was developed. Laser ablation was studied. The machining properties of silicon nitride ceramics by water-assisted laser and laser-assisted water jet are discussed. The effects of process parameters on groove width, groove depth, surface roughness and heat affected zone width are discussed. The laser-assisted water jet machining technology can obtain the groove shape with a larger ratio of depth to width, and its thermal damage is smaller than that of laser ablation and water-assisted laser processing. The water jet pressure has the most significant effect on the groove width and the width of the heat-affected zone. The influence of laser pulse energy on groove depth and the impact angle of water jet on the surface roughness is most significant. The effect of the original surface morphology of the workpiece on the shaping of the machined surface is studied. There are pyrolysis zone, oxidation damage zone and softening deformation zone in the processing zone of silicon nitride ceramics. The processing texture of the original surface of the workpiece is not conducive to improving the surface processing quality. The heat affected zone formed on the original smooth surface is smaller than that formed on the original rough surface. The material removal mechanism of laser assisted water jet processing of silicon nitride ceramics is studied. The material removal mechanism of laser assisted water jet machining silicon nitride ceramics is water jet impingement removal of materials heated and softened by laser and pyrolysis of core region irradiated by laser. A prediction model of groove depth and surface roughness is established. The prediction results of the model are in good agreement with the experimental results and the error is small. The influence of the interaction of process parameters on the groove depth and surface roughness is studied. The influence of transverse offset distance on the groove depth is not significant, but on the machined surface roughness is significant. The effect of laser pulse energy on groove depth is most significant. The influence of water jet pressure on surface roughness is most significant. The interaction between laser pulse energy and water jet pressure has the most significant effect on groove depth and surface roughness. Milling silicon nitride ceramic microstructures and microstructural arrays are feasible. The boundaries of single microgrooves are straight and complete, There is no flanging and edge thermal damage. The microgroove array is uniformly distributed and there is no interference between adjacent microgrooves. A prediction model of microstructural size based on BP artificial neural network is established and verified by experiments. There is good consistency between the predicted value and the experimental value, and the average error of the whole prediction is less than 10%.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ174.6

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