【作者】 王亮；

【导师】 高菲； 郭江；

【作者基本信息】 大连理工大学 ， 机械工程， 2024， 硕士

【摘要】 SLM交叉流道结构因其具有能够优化传输性能以及提高传热、传输介质效率等优势,在航空航天、汽车电子、能源化工、生物医学等领域中被广泛应用。然而由SLM工艺直接制造成型的工件表面往往会存在球化效应、气孔等缺陷,导致内表面质量无法满足相关领域的使用要求,因此需进行抛光后处理。在SLM交叉流道内表面后处理研究中,磨粒流抛光因其具有优良的适应性以及高精度被广泛采用。但现有的磨粒流抛光存在抛光后内表面均匀性差等问题,因此探究SLM交叉流道内表面高效高均匀性抛光具有深远意义。本研究提出一种磨粒流分步叠加抛光方法,研制了面向复杂结构内表面光整加工需求的柔性多接口磨粒流抛光设备,解决了交叉流道内表面抛光后均匀性差的难题。同时,针对交叉流道内表面无损检测困难的问题,提出一种基于复制法的局部复制无损检测方法,满足了交叉流道内表面局部无损检测的需求。主要研究内容如下:(1)提出一种磨粒流分步叠加抛光方法。探究了磨粒流分步叠加抛光方法的机理,建立了磨粒流分步叠加抛光过程中各区段的材料去除模型。基于此方法,完成了柔性多接口磨粒流抛光设备的总体方案设计。并从交叉流道磨粒流抛光设备的高效性能和结构的稳定性出发,完成了设备关键部件的型号选择和参数设计。(2)开展磨粒流分步叠加抛光方法数值模拟。通过Fluent仿真软件对磨粒流分步叠加抛光方法进行了仿真,分析了不同抛光参数条件下流道各区段的壁面剪切力对抛光效果的影响,并对比了采用不同抛光方案组合抛光后各区段的均匀性效果。仿真结果表明,进口的压力越大,磨粒作用到工件表面的壁面剪切力越大,抛光效果越明显,并得到了最优磨粒流抛光方案组合。(3)开展磨粒流分步叠加抛光工艺实验。通过设计的可拆解的316L不锈钢交叉流道结构件对最优方案组合的可行性进行验证。对SLM交叉流道内表面展开实验,结果表明,在碳化硅磨粒粒径200目、浓度0.5-0.6、入口压力10 MPa、抛光45 min的条件下,SLM交叉流道内表面的球化以及粉末黏附等缺陷基本被去除,表面粗糙度由最初的Sa=11.827μm降至Sa=0.855-1.577μm,抛光效果显著,获得的流道各区段内表面质量也相对较均匀。(4)提出基于复制法的局部复制无损检测方法。采用复制法对交叉流道各区段的内表面进行局部复制,并制作局部复制无损检测装置,复制误差保持在10%以内。更多还原

【Abstract】 SLM intersecting flow passages structures are widely used in fields such as aerospace,automotive electronics,energy and chemical engineering,and biomedicine due to their ability to optimize transmission performance and improve heat and mass transfer efficiency.However,parts manufactured directly by the SLM process often exhibit defects such as balling effect and porosity on their surfaces,resulting in insufficient quality of inner surfaces to meet the usage requirements of relevant fields.Therefore,post-polishing treatment is necessary.In the research on post-processing of inner surfaces in SLM intersecting flow passages,abrasive flow polishing is widely adopted due to its excellent adaptability and high precision.However,existing abrasive flow polishing methods suffer from issues such as poor uniformity of the inner surface after polishing.Therefore,exploring the efficient and uniform polishing of the inner surfaces of SLM intersecting flow passages has profound significance.This study proposes an abrasive flow stepwise superimposition polishing method and has developed a flexible multi-interface abrasive flow polishing equipment for the surface finishing requirements of complex structures,addressing the challenge of poor surface uniformity in polishing inner surfaces of intersecting flow passages.Meanwhile,addressing the challenge of difficult detection of inner surfaces in intersecting flow passages,a non-destructive testing method based on replication was proposed,meeting the requirement for localized non-destructive testing of inner surfaces of intersecting flow passages.The main research contents are as follows:(1)Proposed a stepwise superimposition polishing method with abrasive flow.Explored the mechanism of abrasive flow stepwise superimposition polishing method and established material removal models for each section of the stepwise superimposition polishing process.Based on this method,the overall scheme design of the flexible multi-interface abrasive flow polishing equipment has been completed.Furthermore,starting from the efficient performance and structural stability of the intersecting flow passages abrasive flow polishing device,the model selection and parameter design of key components of the equipment have been completed.(2)Conducted numerical simulation of stepwise superimposition polishing method of abrasive flow.Utilizing Fluent simulation software,simulations were performed on the stepwise superimposition polishing method of abrasive flow.The influence of wall shear force on the polishing effect in different sections of the channels under various polishing parameter conditions was analyzed.Furthermore,the uniformity effects of different polishing scheme combinations on each section after polishing were compared.The simulation results indicate that with increased inlet pressure,the wall shear force acting on the workpiece surface by the abrasive particles becomes greater,leading to a more pronounced polishing effect.Additionally,the optimal combination of abrasive flow polishing schemes was determined.(3)Conducted experimental investigation of the stepwise superimposition polishing method of abrasive flow.The feasibility of the optimal scheme combination was validated through experimentation with designed detachable 316 L stainless steel intersecting flow passages structural components.Experimental results from unfolding the inner surfaces of SLM intersecting flow passages indicated that under the conditions of silicon carbide abrasive particle size of 200 mesh,concentration of 0.5-0.6,inlet pressure of 10 MPa,and polishing time of 45 minutes,defects such as spheroidization and powder adhesion on the inner surfaces of the intersecting flow passages were largely eliminated.The surface roughness decreased from the initial Sa=11.827 μm to Sa=0.855-1.577 μm,demonstrating a significant improvement in polishing effect.Additionally,the obtained inner surface quality of the channel sections was relatively uniform.(4)Proposed a non-destructive testing method based on replication for localized replication.The internal surfaces of various sections of intersecting flow passages were locally replicated using the replication method,and a non-destructive testing device for local replication was developed,with replication error kept within 10%.更多还原