Tang L.,Xi'an Technological University |
Fan Z.J.,Xi'an Technological University |
Zhao G.G.,Second B xiAn KunLun Industrial Group Co |
Yang F.,CNGC QIQIHAER NORTH MACHINERY CORPORATION Ltd |
Yang S.,AVIC xiAn Aerospace ENGINE GROUP LTD.
Procedia CIRP | Year: 2016
The tubes with high length to diameter ratio over 100:1 were widely used for spline, weapons, aerospace, screw drill stator of oil and gas drilling components, which are impossible to be machined by conventional techniques. However, electrochemical machining (ECM) has the unique advantages of high efficiency, high surface quality, no stress and no cathode wear in machining difficult-to-cut conductive materials and complicated parts and components. So, we adopted the ECM method to research the key technologies for manufacturing high aspect ratio deep spiral tube in this paper. First of all, we established the ECM cathode model, then through the electrical field simulation to optimize the adduction angle of the cathode teeth with COMSOL software. Secondly, the ECM frock clamps were designed and manufactured, which have the function of the conduction, insulation and sealing. Then, we introduced to develop a 20000A horizontal NC ECM machine tool, which can control the electrolyte temperature between 29°C and 31°C, and can keep 24 hours continuous and stable machining. Finally, through the L9(34) orthogonal array method to carry out our high aspect ratio deep spiral tube electrochemical machining experiment, we obtained the optimal processing parameters. In the condition of 0.1 mm initial machining gap, 10%NaCl electrolyte, 30°C electrolyte temperature, 2.0 Mpa electrolyte pressure, 16 mm/min cathode feed rate we successfully manufactured a 3.5 meters spiral tube with high surface quality in our self-developed machine tool. The simulation results were consistent with the experiment data. The results show that: using the method of electrical field simulation to optimize cathode teeth adduction angle to design cathode can shorten the cathode design cycle and reduce the experiment cost. It indicates that it is a feasible, stable and high-efficiency machining method for ECM to machining these high aspect ratio spiral tubes. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.
Wang S.,Xi'an Jiaotong University |
Li G.,Xi'an Jiaotong University |
Chen X.,Xi'an Jiaotong University |
Xia Y.,AVIC xiAn Aerospace engine Group Ltd. |
Liu Z.,AVIC xiAn Aerospace engine Group Ltd.
Conference Record - IEEE Instrumentation and Measurement Technology Conference | Year: 2013
Conventional time-frequency representation (TFR) methods have played an important role in characterizing the time-frequency (TF) pattern of the nonstationary signal. In this paper, a new TFR algorithm, called matching demodulation transform (MDT), is introduced to extract the feature of highly oscillating frequency modulation for rotor rub-impact fault. When the early rub-impact fault occurs in the rotor system, the vibration signals will present frequency modulation feature because of the periodic rub-impact between the stator and the rotor. Through an iterative demodulation procedure, the highly oscillating frequency modulation feature is represented with satisfactory energy concentration in TF plane. The validity of the technique is then demonstrated on a real rotor system of a gas turbine with rub-impact fault. The analysis result of this application shows that the MDT method is powerful in the analysis of frequency modulation signals and is an effective tool for the feature extraction of rub-impact faults. © 2013 IEEE.
Zhang P.,PLA Air Force Aviation University |
Chang Y.-T.,AVIC Xian Aerospace Engine Group Ltd.
Proceedings - International Conference on Natural Computation | Year: 2012
Considering determining the number of software fault is an uncertain non-linear problem with only small sample, a novel software fault prediction method based on grey neural network is put forward. Firstly, constructing the grey neural network topological structure according the small sample sequence is necessary, and then the network learning algorithm is discussed. Finally, the grey neural network prediction model based on the grey theory and artificial neural network is proposed. The sample fault sequences of some software project are used to verify the precision of this method. Comparison with GM(1,1), the proposed model can reduce the prediction relative error effectively. © 2012 IEEE.
Yang D.Y.,Beijing Institute of Electro Machining |
Cao F.G.,Beijing Institute of Electro Machining |
Liu J.Y.,Beijing Institute of Electro Machining |
Yang L.G.,Beijing Institute of Electro Machining |
And 2 more authors.
Procedia CIRP | Year: 2013
In recent years, with the development of the researches on aviation, space and energy fields, integral impeller, blisk, shrouded turbine blisk and hooded impeller have been used more and more broadly. The construction of these key parts is complex. Their weight is lighter than before. Their structural strength is enhanced. Their reliability and efficiency are greatly improved. And these parts are made of anti-high temperature and corrosion resistance materials. These characters make it difficult to machine them precisely. In this paper, five-axis EDM equipment is developed to solve this problem. Based on this equipment, the processing techniques of integral impeller, blisk, shrouded turbine blisk and hooded impeller are researched. And the electrodes are designed. The discharge conditions and machining trajectories are optimized. Finally, the eligible work pieces such as shrouded turbine blisk and hooded impeller have been made by using the research result. © 2013 The Authors.
Zhao Z.,Northwestern Polytechnical University |
Liu R.,China Aerospace Science and Technology Corporation |
Tian Q.,AVIC Xian Aerospace Engine Group Ltd.
Zhongguo Xitu Xuebao/Journal of the Chinese Rare Earth Society | Year: 2015
Based on the principles of high melting point, densities, nearly lattice matching and so on, two kinds of three elements rare-earth intermetallic compound of YNi2Si2 and CeCo4B were selected by the self-made superalloy refining agents selection system. Using argon arc welding method, two kinds of rare-earth intermetallic compound were used as the coating material, the superalloy of K4169 was used as substrate, a common molten pool was formed and solidified, macro/micro structure observation found that containing Ce and Y rare-earth intermetallic compounds both have a certain inhibitory effects on the dendritic growth of substrate γ-phase. The experiment of directly pouring the cylindric castings of K4169 superalloy at the temperature 1470 ℃ showed that the average grain sizes were reduced from 3.57 mm without any addition to 0.92 mm with addition of mixed rare-earth refining agents. © 2015, Chinese Rare Earth Society. All right reserved.
Shang T.-S.,Northwestern Polytechnical University |
Zhao M.,Northwestern Polytechnical University |
Chen Y.-H.,AVIC Xian Aerospace Engine Group Ltd.
Tuijin Jishu/Journal of Propulsion Technology | Year: 2015
To find the more accurate method to forecast materials low cycle fatigue life, the mechanism causing the material fatigue damage were analyzed and a life prediction model that describes the relation between damage energy density and fatigue life was proposed based on the Formula of Three-Parameter Power Function. The low cycle fatigue experimental data of supperalloy and titanium alloy were used to verify the damage energy density model, then, compared its analysis results with the traditional Masson-Coffin model and the Formula of Three-Parameter Power Function's. The results show that the fitting effect in different conditions of damage energy density model is better than the other two models, in the fitting results of seven conditions, there are six kinds of correlation coefficient being more than 0.9, the damage energy density model has a higher life prediction accuracy and its life forecasting points in seven different conditions are all in the 2 scatter band. In addition, this model is simple and can exactly describe the reason for the low cycle fatigue damage of materials. ©, 2015, Editorial Department of Journal of Propulsion Technology. All right reserved.
Wu B.,Northwestern Polytechnical University |
Han F.,Northwestern Polytechnical University |
Yang J.,Northwestern Polytechnical University |
Qin T.,AVIC Xian Aerospace engine Group Ltd.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2012
For milling of free-form impeller channel using nonorthogonal 4-axis machine, a tool axis control method was proposed, which interpolated tool axis by rotating it through a revolution axis in a constraint surface. Through analyses of the tool axis constraint conditions, a unit cone which met the constraint conditions was established in work coordinate system. An algorithm was presented to calculate initial tool axis of the clean-up machining, then the interference-free tool axis of every contact point was generated in a clean-up tool path. Sequentially the surface area on the unit cone was calculated, which determined by the corresponding clear-up tool axis, and interpolated clean-up tool axis by rotating it in a same angle on this area to get the tool axis of the impeller channel milling, finally a machine kinematics constraints was established to smooth it. Examples show that the method can calculate the smooth and interference-free tool axis of the impeller channel accurately and efficiently when it is machined by using non-orthogonal 4-axis machine.
Tang L.,Xi'an Technological University |
Tang L.,Changzhou Institute of Technology |
Li B.,Xi'an Technological University |
Yang S.,AVIC xiAn Aerospace ENGINE GROUP LTD. |
And 2 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2014
Selecting an appropriate electrolyte is very important for high-efficiency electrochemical machining novel S-03 special stainless steel aerospace component. A series of experiments were conducted with NaCl, NaNO3, and their admixture solutions. This research focused on the relationship between current efficiency and current density. The current density effects on surface roughness, machining velocity, and grain boundary corrosion were analyzed. The results showed that: the current efficiency in NaCl electrolyte was 100 % with different concentrations. Under the conditions of 24 V voltage, 30 °C electrolyte, and 0.8 MPa electrolyte pressure, the 10 % NaCl electrolyte can obtain 3.6 mm/min cathode feed speed; the surface roughness is Ra 0.08 μm; and the material removal rate is 411.4 mm3/min. Comparing forward flow to forward flow with added backpressure, we found that: the surface roughness value decreased sharply at 3.6 mm/min in NaCl electrolyte. © 2014 Springer-Verlag London.
Zhong J.-Y.,Aerospace Research Institute of Materials And Processing Technology |
Mu R.-D.,Aerospace Research Institute of Materials And Processing Technology |
He Y.,AVIC Xian Aerospace Engine Group Ltd. |
He L.-M.,Aerospace Research Institute of Materials And Processing Technology
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2013
A metallic protective coating on the third generation single crystal superalloy was investigated. The coating surface, interface morphology and phase structure of the organization were characterized by scanning electron microscopy(SEM), energy dispersion X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Interdiffusion behavior of coatings and cyclic oxidation kinetics were analyzed. A single NiCoCrAlYHf coating was deposited onto the single crystal superalloy by arc ion plating (AIP). The results showed that an interdiffusion zone (IDZ) were formed in Ni-based single crystal superalloy after 600h heat treatment at 1100°C in the atmospheric environment. The elemental interdiffusion between the coating and the substrate occured as Al diffuse inward from the coating to the substrate and Cr diffuse outward from the substrate to the coating. There were amounts of topologically close-packed phases (TCP) precipitated under coating 60 μm in the superalloy and ultimately came into being secondary reaction zone (SRZ).
Xu J.,Lanzhou University of Technology |
Yang S.,Lanzhou University of Technology |
Zhang L.,Avic Xian Aerospace engine Group Ltd. |
Kang Z.,Lanzhou University of Technology |
Guo Q.,Lanzhou University of Technology
Advanced Materials Research | Year: 2011
The nano-antimony particles with different shape, size and stability are prepared by electrochemical method under the dilute hydrochloric acid electrolyte including the surface dispersant OP-10 and different current densities. The influences of current density on the shape and size of nanometer antimony particles prepared by electrochemical method are analyzed by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The results show that nano-antimony powder can be prepared by electrochemical method, and the antimony powder possesses the crystal structure with orthorhombic hexahedron. The current density has a significant impact on the agglomeration, shape and size of antimony powder. The size and shape of antimony powder are determined by the nucleation rate of nano-antimony and combination capacity of antimony ions and OP-10 surface dispersing agents affected by current density. When the current density is 25mA/cm2, the average particle size is 12nm or so, the shape is spherical, and the nano-antimony particles are well dispersed and no agglomeration. © (2011) Trans Tech Publications.