航空用不锈钢磨粒流光整加工表面完整性研究

为研究磨粒流光整加工不锈钢闭式整体叶环的表面完整性，通过对电火花制备的不锈钢试样进行加工时间、加工压强及磨料目数的单因素试验，研究3个因素对加工后表面完整性的影响。结果表明：表面粗糙度Ra随着加工时间的增加而降低，从初始时的1.459μm降至60 min时的0.193μm，降低速率越来越慢，最后趋于稳定。磨粒流加工有效去除了加工表面再铸层。显微硬度在加工后明显降低，由450～950 HV降至270～350 HV且分布均匀性得到改善。显微硬度随着加工时间的增加整体上呈降低趋势，并出现了一定的加工硬化现象。在使用不同目数的磨料进行磨粒流加工后，残余应力由拉应力变为压应力。随着加工时间和加工压强的增加，试样表面越平整，抛光效果越好。     

加工装配误差影响下偏转射流压力伺服阀静态特性分析

电液压力伺服阀是电液压力伺服控制系统的核心控制元件，广泛应用于航空、航天、军事等领域。区别于流量伺服阀，压力伺服阀在滑阀放大器的设计上多采用带有压力控制容腔的三通阀结构，不同的滑阀结构使得现有的偏转射流流量伺服阀仿真模型难以满足压力伺服阀性能预测的需求。本文基于AMESim平台建立了偏转射流压力伺服阀的仿真模型，并通过实验对仿真模型进行了验证，验证结果表明仿真模型能够准确地描述压力伺服阀的静态特性。最后，通过仿真模型分析了加工装配误差影响下压力伺服阀输出性能差异，仿真结果可为偏转射流压力伺服阀的性能预测和结构设计提供参考。     

Improving performance of macro electrolyte jet machining of TC4 titanium alloy: Experimental and numerical studies

Electrolyte jet machining (EJM) is a promising method for shaping titanium alloys due to its lack of tool wear, thermal and residual stress, and cracks and burrs. Recently, macro-EJM has attracted increasing attention for its high efficiency in machining wide grooves or planes. However, macro-EJM generates large amounts of electrolytic products, thereby increasing the difficulty of rapid product removal with a standard tool and reducing the surface quality. Therefore, for enhanced product transport, a novel tool with a back inclined end face was proposed for macro-EJM of TC4 titanium alloy. For comparison, also proposed were ones with a standard flat end face, a front inclined end face, and both front and back inclined end faces. The flow field distributions of all proposed tools were simulated numerically, and experiments were also conducted to validate the simulation results. The results show that one with a 5° back inclined end face can decrease the low-velocity flow zone in the machining area and increase the high-velocity flow zone at the back end of tool, thereby promoting rapid product removal. A relatively smooth bright-white groove surface was obtained. The same tool also resulted in the highest machining depth and material removal rate among the tested ones. In addition, rapid product removal was beneficial to the subsequent processing. Because of its rapid product removal, the machining depth and material removal rate during deep groove machining using the tool with a 5° back inclined end face were respectively 7% and 14% higher than those produced using a standard one. Moreover, the lowest bottom height difference of 0.027 mm can be obtained when the step-over value was 8.2 mm, and a plane with a depth of 0.285 mm and a bottom height difference of 0.03 mm was fabricated using the tool with a 5° back inclined end face.