磨料水射流对脆性材料的冲蚀研究

摘要

磨料水射流技术作为一种特种加工技术,具有无刀具接触、无热影响区和加工范围广等优势,在众多领域得到应用.为了探究磨料水射流对脆性材料的冲蚀效果,构建和设计了磨料水射流外流场冲蚀仿真模型与磨料水射流冲蚀实验.以30mm×50mm的喷嘴外流场域为计算域,建立磨料水射流冲蚀仿真模型,并分析射流冲蚀过程中压力分布、水与磨料的速度分布及它们在射流中心线上的衰减规律.通过对氧化铝陶瓷材料的冲蚀实验,分析工艺参数对冲蚀孔径的影响,并结合仿真结果对比分析了射流束宽度与冲蚀孔径的关系.结果表明:水的速度随着喷嘴距离的增大而减小且分布范围变宽,射流宽度呈线性增大,磨料速度随喷嘴距离的增大而减小且分布范围基本不变;射流中心线上水的速度与磨料速度呈三段式衰减,水的第1段速度衰减段长度比磨料的长,但水的第2段速度衰减段长度比磨料的短;射流束能量的有效利用部分逐渐减小,但在15～25mm的靶距范围内其有效利用部分较稳定,为40％;冲蚀孔径随喷嘴距离增大呈线性增大.研究结果为磨料水射流切割、铣削及抛光加工的参数选择提供实验依据,同时为磨料水射流加工过程仿真提供参考.%Abrasive water jet technique is a special process popularized and applied in many fields due to its advantages like no tool contact, no heat-affected zone and high machining versatility, etc.In order to investigate the erosion effect on brittle materials, the erosion simulation model of abrasive water jet at outer flow field and abrasive water jet erosion experiment were designed.The abrasive water jet erosion simulation model was set up based on the 30 mm×50 mm outer flow field of the nozzle.The distribution of pressure, velocity of water and abrasive and their attenuation law on the center line of jet in the erosion process were fully analyzed.Through the erosion test of alumina ceramic material, the influence of process parameters on the erosion hole diameter was analyzed as well.Combining with the simulation results, the relationship between jet beam width and erosion hole diameter was compared and analyzed.The results indicated that the water velocity decreased with the increase of nozzle distance and the distribution range became wider, and the width of jet increased linearly.The abrasive velocity decreased with the increase of nozzle distance while the distribution width was almost unchanged.The velocity of water and abrasive on the center-line of jet showed three-stage attenuation.During the first stage, the length of the velocity attenuation section of water was longer than that of abrasive, but during the second one, the length of the velocity attenuation section of water was shorter than that of abrasive.In addition, the effective utilization of jet energy decreased gradually.However, in the target range of 15～25 mm, the effective utilization part was more stable at around 40％, and the erosion hole diameter increased linearly with the nozzle distance increasing.The research results can provide experimental basis for the parameter selection of abrasive water jet cutting, milling and polishing, and provide reference for the simulation of abrasive water jet machining.