【作者】 于洋；

【导师】 王宣平； 陈亮；

【作者基本信息】 大连理工大学 ， 机械工程（专业学位）， 2020， 硕士

【摘要】 磨料水射流切割技术自上世纪70年代正式进入工业制造领域以来,经过快速的发展,成为了一项极具优势的冷态加工工艺。由于其具有切削力小、无热影响区等特有的优势,因此适用于多种难加工材料的切割加工,并且相较于传统加工还有着高效率、低成本和绿色环保等优点。本文对磨料水射流切割工艺参数优化进行了实验研究,为在实际应用中进一步实现磨料水射流高质高效的切割工艺提供了一定的参考。本文以优化磨料水射流切割工艺参数为研究目标,从推导磨料水射流切割深度理论出发,通过实验分别研究了磨料水射流切割中加工参数的优化和磨料参数对加工性能的影响。通过磨料水射流切割深度理论的推导,分析了射流基本结构与各个阶段自由射流与磨料的速度状态及分布。通过将主要工艺参数与材料去除率相关联,并结合无量纲分析的方法给出了切割深度的半经验预测模型。结合射流能量分布理论与实际加工中切缝几何形状的特点,建立了切缝轮廓的几何模型,并由模型进一步分析给出了有效切割深度的判定与测量方法。将切缝正交实验中所提取的极限深度与有效深度带入切割深度预测模型,可以标定模型中的各系数值并得到完整的切割深度预测模型。通过Box-Behnken设计方法,分析了各加工参数对切割深度的具体影响,发现进给速度和磨料流量是对切割深度影响较大的两个参数。进一步对两两参数的交互影响进行了讨论,结果发现压力和磨料流量的变化会对靶距选择产生一定影响。针对不同磨料条件分别进行了单磨料和混合磨料的切割实验,并测定了不同磨料条件下磨料水射流的切割能力与切割质量。设计了两种切割实验用以观测当使用单磨料时不同的磨料材料、粒径和流量对加工效果的影响。实验结果发现,氧化铝由于具有较高的圆度和相对合适的硬度,因此表现出较好的加工性能。进一步对混合磨料进行实验,发现当使用质量分数为75%的氧化铝和25%的石榴石混合磨料时,在磨料粒径为120#、流量为130g/min的条件下,可以得到最大切深41.7mm和最低粗糙度Ra2.1μm。更多还原

【Abstract】 Since the abrasive waterjet cutting technology formally entered the industrial manufacturing field in the 1970 s,it has become a very advantageous cold processing technology after rapid development.Because of its unique advantages such as small cutting force and non heat affected zone,it is suitable for cutting a variety of difficult to machine materials,and has the advantages of high efficiency,low cost and environmental protection compared with traditional processing.Therefore,this paper studies the enhancement and optimization of the cutting performance of the abrasive water jet,which provides a reference for further realizing the high quality and high efficiency cutting process of the abrasive water jet in practical application.In this paper,the optimization of cutting process parameters of abrasive waterjet is taken as the research goal.Based on the basic theory of cutting depth of abrasive waterjet,the optimization process of cutting parameters in abrasive water jet cutting and the influence of Abrasive Parameters on cutting performance are studied,respectively.Through the derivation of the theory of abrasive waterjet,the basic structure of the jet and the velocity state and distribution of free jet and abrasive in each stage are analyzed.The prediction model of cutting depth is given by associating the main process parameters with the material removal rate and combining the dimensionless analysis method.Combined with the theory of jet energy distribution and the characteristics of kerf shape in practical machining,the kerf geometry model is established,and the judgment and measurement method of effective cutting depth are given by further analysis of the model.Through the Box-Behnken design method,the specific influence of each processing parameter on the cutting depth is analyzed,and it is found that the traverse speed and abrasive flow rate are the two parameters that have great influence on the cutting depth.Furthermore,the interaction between the two parameters is discussed,and it is found that the pressure and the abrasive have some influence on the stand-off distance.According to different abrasive conditions,the cutting experiments of monolithic abrasive and mixed abrasive were carried out,and the cutting ability and cutting quality of abrasive water jet under different conditions were measured.Two kinds of cutting experiments are designed to observe the effect of different abrasive materials,particle mesh size and flow rate on the machining effect when monolithic abrasive is used.The results show that alumina has better processability because of its high roundness and relatively suitable hardness.Through experiments on the mixed abrasive,it was found that when using the mixture of alumina with mass fraction of 75% and garnet with mass fraction of 25%,the maximum cutting depth of 41.7mm and minimum roughness of ra2.1m could be obtained under the condition of abrasive particle mesh size of 120# and flow rate of 130g/min.更多还原