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Efflcient machining of a complex blisk channel using a disc cutter

Chinese Journal of Aeronautics 2024年第1期37卷 414-437页

作者： Xiangyu LI Zhaoyu LI Dong HE junxue ren Qian FENG Kai TANG Department of Mechanical and Aerospace Engineering Hong Kong University of Science and TechnologyHong Kong 999077China Key Laboratory of High Performance Manufacturing for Aero Engine(Northwestern Polytechnical University) Ministry of Industry and Information TechnologyXi’an 710072China Xi’an Sanhang Power Technology Co. LtdXi’an 710000China HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute FutianShenzhen 518057China HKUST Shenzhen Research Institute Shenzhen 518057China

For rough machining of a complex narrow cavity,e.g.,a complex blisk channel on an aero-engine,the typically used cutting tools are the slender cylindrical cutter and conical cutter.Nevertheless,as neither of the two is particularly suited for rough machining,wherein the main purpose is to remove a large volume as quickly as possible,the machining efficiency is low,especially when the part materials are of hard-to-cut types(e.g.,Titanium-alloy)for which it often takes days to rough machine a blisk.Fortunately,disc machining provides a new and efficient roughing solution,since a disc cutter with a large radius enables a much larger cutting speed and thus a larger material removal rate.However,due to the large radius of the disc cutter,its potential collision with narrow and twisted channels becomes a serious concern.In this paper,we propose a novel twophase approach for efficiently machining a complex narrow cavity workpiece using a disc-shaped cutter,i.e.,3+2-axis disc-slotting of the channel by multiple layers(rough machining)+five-axis disc-milling of the freeform channel side surfaces(semi-finish machining).Both simulation and physical cutting experiments are conducted to assess the effectiveness and advantages of the proposed method.The experimental results show that,with respect to a same cusp-height threshold on the channel side surfaces,the total machining time of the tested part by the proposed method is about only 36%of that by the conventional approach of plunging-milling(for roughing)plus milling by a slender cylindrical cutter(for semi-finishing).

关键词： Blisk channel CNC machining Disc cutter Roughing efficiency Tool path planning

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The azimuthal currents in the ion-driven magnetic nozzle

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Propulsion and Power Research 2022年第4期11卷 457-472页

作者： Zhiyuan Chen Yibai Wang Haibin Tang junxue ren Min Li Peng Wu Jinbin Cao School of Astronautics Beihang UniversityBeijing102206China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of EducationBeijing102206China Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing102206China Innovation Academy of Microsatellites Chinese Academy of SciencesShanghai201203China School of Space and Environment Beihang UniversityBeijing102206China

Ion-driven magnetic nozzles(Ti>Te)are designed as intrinsic parts of cutting-edge propulsive technologies such as variable specific impulse magnetoplasma rockets(VASIMRs)and applied-field magnetoplasmadynamic thrusters.Employing a two-dimensional axisymmetric particle-in-cell(PIC)code,in the ion-driven magnetic nozzle,the compositions and distributions of azimuthal currents in different axial regions are investigated under various inlet ion temperatures Ti0 and found to differ dramatically from that in the electron-driven magnetic nozzles.Previously reported to be all paramagnetic and vanishing under a high magnetic field,the azimuthal currents resulting from the E 3 B drift are shown to turn diamagnetic and sustain a considerable magnitude when Ti0 is considered.The previously reported profile of diamagnetic drift current is altered by the introduction of inlet ion temperature,and the paramagnetic part is significantly suppressed.Moreover,a wide range of paramagnetic currents appear downstream due to the inward detachment of ions,which can also be reduced by increasing inlet ion temperature.Albeit considered in this paper,the azimuthal currents resulting from grad-B and curvature drift are still negligible in all cases of interest.The magnitude of diamagnetic azimuthal currents increases with amplifying Ti0,indicating a clear physical image of energy transformation from ion thermal energy to the directed kinetic energy through electromagnetic processes in the magnetic nozzle.Additionally,the magnetic inductive strength also has noticeable impacts on the azimuthal currents,the current magnitude tends to decrease as the magnetic field increases,and over-increment of it may result in larger divergence angles and lower nozzle efficiency.

关键词： Magnetic nozzle Azimuthal current Ion temperature Electric propulsion

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Surface integrity and fatigue behavior when turning γ-TiAl alloy with optimized PVD-coated carbide inserts

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Chinese Journal of Aeronautics 2018年第4期31卷 826-836页

作者： Changfeng YAO Jiannan LIN Daoxia WU junxue ren The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

This paper presents a comprehensive investigation on the effects of tool and turning parameters on surface integrity and fatigue behavior in turning c-Ti Al alloy. The wear of inserts surface, cutting forces, and surface roughness were studied to optimize PVD-coated carbide inserts.Surface topography, residual stresses, microhardness, and microstructure were analyzed to characterize the surfaces layer under different turning parameters. Surface integrity and fatigue life tests of c-Ti Al alloy were conducted under turning and turning-polishing processes. The results show that compared to CNMG120412-MF4, CNMG120408-SM is more suitable because it obtained low cutting force, surface roughness, and tool wear. With increasing the cutting speed and depth, the depths of the compressive residual stress layer, hardening layer, and plastic deformation layer increased. For turning and turning-polishing specimens, the compressive residual stress was relaxed by less than 20%–30% after 10^7 cycles. The fatigue life of a turning-polishing specimen with Ra= 0.15 mm has increased 3 times from that of a turning specimen with Ra= 0.43 mm.

关键词： Fatigue behavior Microhardness Residual stress Surface roughness γ-TiAl alloy Tool wear

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A novel method for solving shortest tool length based on compressing 3D check surfaces relative to tool postures

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Chinese Journal of Aeronautics 2021年第2期34卷 641-658页

作者： Xiangyu LI junxue ren Ximing LV Yuke ZHOU Congle LIU Key Laboratory of High Performance Manufacturing for Aero Engine(Northw estern Polytechnical University) Ministry of Industry and Information TechnologyXi'an 710072China

Solving the shortest tool length quickly under a known tool trajectory in multi-axis machining of complex channel parts is an urgent problem in industrial production. To solve this problem, a novel and efficient method is proposed which is featured by extracting only a few necessary curves from the check surface instead of sampling the entire surface. By rotating and compressing the 3 D check surface relative to all tool postures, the boundaries of the area occupied by the 2 D compressed surfaces are the essential elements for determining the shortest tool length. A tracking-based numerical algorithm is introduced to efficiently solve the silhouette curves which are formed in compressing. To define the multi-taper shaped tool holding system(THS) which is commonly used in production, a characterization model for THS profile is established. A model for solving the shortest tool length is finally constructed based on the critical interference relationship between the THS profile and all compressed boundary curves. For acceleration, the boundary splines are segmented according to their knot vectors. Then a new concept called the axis-aligned tool length box(AATB) is introduced,which can provide a conservative range of tool length for a spline segment. By scanning the AATBs of all spline segments, the very few effective spline segments that may ultimately determine the shortest tool length are filtered out. This acceleration method makes the solution for the shortest tool length more focused and efficient. The results of experimental examples are also reported to validate the efficiency and accuracy of the proposed algorithm.

关键词： CNC Compressed check surface Multi-axis machining Shortest tool length Silhouette curve Tool holding system

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Coupling plasma plume of a low-power magnetically shielded Hall thruster with a hollow cathode

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Chinese Journal of Aeronautics 2020年第12期33卷 3018-3026页

作者： Guangchuan ZHANG junxue ren Wei LIANG Ning OUYANG Chao LU Haibin TANG School of Space and Environment Beihang UniversityBeijing 100083China School of Astronautics Beihang UniversityBeijing 100083China Shanghai Institute of Space Propulsion Shanghai 201112China Key Laboratory of Spacecraft Design Optimization&Dynamic Simulation Technologies Ministry of EducationBeijing 100083China Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100083China

The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster plume.The characteristics of plasma in that region are complicated and strongly associated with the thruster working conditions and the cathode position.In this paper,a laboratory 100 W class magnetically shielded Hall thruster was coupled with a hollow cathode.Optical imaging and electrostatic probe were employed to monitor and scan the plasma plume.Plume characteristics in the coupling region in non-self-sustained mode and self-sustained mode were compared.Evolution of the coupling plume with the cathode position was studied.Experiments show that,when turning the thruster into self-sustained mode or moving the cathode further away axially,the discharge current can be reduced by 6.4–10.6%restraining the electron current and improving ionization.In particular,when the cathode is moved further,the electron conduction near the channel walls is suppressed.The electron current is reduced by 27.4%and the ion beam current is increased by 7%.Overall,this work shows that the working mode of the thruster and the position of the cathode greatly affect the coupling plasma plume.Both play an important role in improving the utilizations of propellant and current.

关键词： Coupling region Electron conduction Hall thruster Hollow cathode Utilizations of propellant and current

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薄壁结构加工误差预测与控制研究进展

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航空制造技术 2024年第7期67卷 77-95页

作者：张瑞任军学张淑宁周金华西北工业大学航空发动机高性能制造工业和信息化部重点实验室西安710072

薄壁结构因质量轻、比强度高被广泛应用于航空航天领域,但因其结构复杂、刚性弱、材料去除率高等特点,铣削加工的零件成品容易出现形位误差,严重影响其使用性能,因此对薄壁结构加工误差的控制具有重要现实意义。通过对薄壁结构加工特点... 详细信息

薄壁结构因质量轻、比强度高被广泛应用于航空航天领域,但因其结构复杂、刚性弱、材料去除率高等特点,铣削加工的零件成品容易出现形位误差,严重影响其使用性能,因此对薄壁结构加工误差的控制具有重要现实意义。通过对薄壁结构加工特点进行分析,总结薄壁结构加工误差来源;根据加工误差来源介绍了薄壁结构不同类型的加工误差,即装夹定位、切削负载、切削振动、机床误差、残余应力以及多工序加工引起的加工误差;然后从这6个方面总结归纳薄壁结构加工误差的预测模型和控制方法;最后阐述了薄壁结构铣削加工误差控制方法的当前挑战和未来发展趋势。

关键词：薄壁结构加工误差多轴铣削变形预测与控制智能加工

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基于三维粗糙度的多向CFRP铣削加工刀具切入角度的优化方法研究

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航空制造技术 2024年第4期67卷 123-131页

作者：刘聪乐任军学张雅莉史恺宁西北工业大学航空发动机高性能制造工业和信息化部重点实验室西安710072

碳纤维增强复合材料(Carbon fiber reinforced plastic,CFRP)因其优良的力学性能,被广泛应用于航空航天领域。CFRP的应用在保证飞机刚度强度的前提下,有效地提高了飞行性能,减轻了飞机重量,从而达到了节能减排的目的,提高了航空工业的... 详细信息

碳纤维增强复合材料(Carbon fiber reinforced plastic,CFRP)因其优良的力学性能,被广泛应用于航空航天领域。CFRP的应用在保证飞机刚度强度的前提下,有效地提高了飞行性能,减轻了飞机重量,从而达到了节能减排的目的,提高了航空工业的经济效益。CFRP属于典型的难加工材料,为了保证结构件在多个方向具有一定的承载能力,航空发动机工业中一般采用CFRP多向铺层,这就使得材料的各向异性及不均匀性更为复杂。本文对CFRP单向层合板和两种CFRP多向层合板的铣削加工断裂机制进行了分析,发现CFRP铣削加工时,不同的纤维方向角对断裂机制有较大的影响从而导致了不同的表面质量。其中,弯曲断裂会导致表面质量急剧下降,应尽量避免,并且不同角度下的弯曲断裂的表面质量也具有一定差异。基于此,提出了多向CFRP铣削加工时的刀具切入角度优化方法,并通过试验验证了该方法的合理性,该方法可以有效提高某型号发动机的第一级复合材料风扇叶片的加工质量。

关键词：多向CFRP 铣削加工刀具切入角度优化三维粗糙度各向异性

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基于道路滑行的多种车型阻力系数外推研究

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农业装备与车辆工程 2024年第7期62卷 82-86页

作者：任俊学王贝贝上海机动车检测认证技术研究中心有限公司上海201805

通过研究多种车型的道路滑行阻力系数,为阻力系数外推提供改进的方向,从而达到阻力系数优化的目的。对试验场多年积累的滑行数据进行研究,归纳总结出3种车型滑行阻力系数数据,分析试验质量、迎风面积对阻力系数的影响,并外推出一种计算... 详细信息

通过研究多种车型的道路滑行阻力系数,为阻力系数外推提供改进的方向,从而达到阻力系数优化的目的。对试验场多年积累的滑行数据进行研究,归纳总结出3种车型滑行阻力系数数据,分析试验质量、迎风面积对阻力系数的影响,并外推出一种计算阻力系数的数学方法,以提高滑行试验的效率,满足企业排放试验需求。

关键词：滑行试验阻力系数外推研究

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Tool Path Optimization for the Blade Spiral Machining

Tool Path Optimization for the Blade Spiral Machining

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2007国际机械工程与力学会议

作者： Chenwei SHAN Dinghua ZHANG Weiwei LIU junxue ren Xiaojun LIN The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of Education Northwestern Polytechnical University

This paper presents an optimization approach that generates a smooth tool path for four or five-axis spiral machining of blades. Firstly, based on the primary curvature radiuses and parameter characteristics, the blade surface is subdivided into four regions including suction surface subarea, pressure surface subarea, leading and trailing edge surface subareas. Geometric algorithms are proposed for partitioning blade surface regions. In order to overcome the overcut on leading and trailing edges, the optimized spiral machining strategy is further developed for blades. The blade surfaces can be cut continuously with minimum tool retractions during the cutting operations. When the suction and pressure surfaces are machined, the cutter can pass by the leading and trailing edges without overcut rapidly, and it allows blades to be machined at high speed. Finally, successful experimental results are given to testify the proposed approach. The result shows that the methods this paper presented can improve the blade machining quality, especially near the leading and trailing edges.

关键词： Blade Spiral machining freeform surfaces machining Tool path

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Development of Kabila rocket: A radioisotope heated thermionic plasma rocket engine

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Chinese Journal of Aeronautics 2015年第2期28卷 427-433页

作者： Kalomba Mboyi ren junxue Liu Yu School of Astronautics Beihang University

A new type of plasma rocket engine, the Kabila rocket, using a radioisotope heated thermionic heating chamber instead of a conventional combustion chamber or catalyst bed is intro- duced and it achieves specific impulses similar to the ones of conventional solid and bipropellant rockets. Curium-244 is chosen as a radioisotope heat source and a thermal reductive layer is also used to obtain precise thermionic emissions. The self-sufficiency principle is applied by simultane- ously heating up the emitting material with the radioisotope decay heat and by powering the differ- ent valves of the plasma rocket engine with the same radioisotope decay heat using a radioisotope thermoelectric generator. This rocket engine is then benchmarked against a 1 N hydrazine thruster configuration operated on one of the Pleiades-HR-1 constellation spacecraft. A maximal specific impulse and power saving of respectively 529 s and 32% are achieved with helium as propellant. Its advantages are its power saving capability, high specific impulses and simultaneous ease of storage and restart. It can however be extremely voluminous and potentially hazardous. The Kabila rocket is found to bring great benefits to the existing spacecraft and further research should optimize its geometric characteristics and investigate the physical principals of its operation.

关键词： Plasma Radioisotopes Rocket Self-sufficiency principleThermionic Thermoelectric power

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