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Implementation strategies for high accuracy grinding of hydrodynamic seal ring with wavy face for reactor coolant pumps

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Science China(Technological Sciences) 2013年第10期56卷 2403-2412页

作者： FENG Guang GUO DongMing HUO FengWei JIN ZhuJi KANG RenKe key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of Technology

Large size mechanical seals are one of the most important components used in reactor coolant ***,the hydrodynamic seal rings with wavy face are difficult to machine due to their high hardness and high form accuracy *** order to solve this difficult problem,a novel four-axis linkage grinding method using a cup wheel to process the hydrodynamic seal rings by line contact was proposed.A preliminary study indicates that the form error of the ground seal ring surface is extremely sensitive to different linkage relations of the four *** taking the center height of the cup wheel and the laws of motion along the X-axis,Z-axis,B-axis and C-axis as control variables,their effects on the principle form error of the ground surface are *** implementation strategies are proposed to reach lower principle form *** is found that the minimal principle form error is only 9.64 nm and hence its influence on the ground seal ring shape can be neglected in designing an ultra-precision grinding *** addition,the results indicate that the position accuracy of the X-axis at the microscale is acceptable no matter which implementation strategy is *** study is expected to serve as a theoretical basis for design and development of the four-axis ultra-precision grinding machine.

关键词： reactor coolant pump hydrodynamic seal ring wavy face grinding cup wheel high accuracy

A model for nanogrinding based on direct evidence of ground chips of silicon wafers

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Science China(Technological Sciences) 2013年第9期56卷 2099-2108页

作者： ZHANG ZhenYu HUO YanXia GUO DongMing key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of Technology

Nanometer chips were directly fabricated using face nanogrinding carried out by ultrafine diamond grits at room temperature. Direct evidence for ground nanometer chips is cuboid, and the average ratio of width to thickness is 1.49. Chips of 9.0 nm in thickness, 13.3 nm in width, and 16.0 in diagonal were achieved and confirmed using transmission electron microscopy. Based on the nanometer chips observed, a model was proposed according to the mass conservation and fundamental mechanism of face grinding. The surface roughness and thickness of damaged layers measured experimentally are in good agreement with the prediction of the developed model. The feed rate significantly affects the surface roughness and thickness of damaged layers, when keeping the wheel and table speeds constant, respectively.

关键词： nanometer chip nanogrinding surface roughness si wafer TEM

Interference mechanism and damage accumulation in high-speed cross scratches on hard brittle materials

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Chinese Journal of Aeronautics 2022年第3期35卷 579-591页

作者： Feifei ZHAO Bin LIN Yuanping HE Tianyi SUI key laboratory of Advanced Ceramics and machining technology Ministry of EducationTianjin UniversityTianjin 300350China

precision and low damage grinding of aviation optical elements can effectively improve the overall processing *** mechanism of high-speed cross scuffing of multiple abrasive particles has become an important factor affecting the forming quality of *** of abrasive trajectory determines machined surface and subsurface morphology and *** to the relative motion trajectory of wear particles on the workpiece surface,a theoretical model of the trochoidal trajectory intersection angle is ***-speed scratches with different cross angles are experimentally obtained to explore the interference mechanism and damage accumulation of cross *** results indicate that the Crack system I and Crack system II,produced by the two cross scratches,are mainly based on the stress principle and the strength principle,*** increase in the damage radius is observed with a decrease in the crossing ***,as the duration of the normal cutting force decomposition curve at the entrance/exit of the intersection increases,the half-peak width also *** accumulation of cross-scratch damage promotes the propagation of deep subsurface lateral and median *** other words,damage accumulation and interference mechanism formed by the cross scratches increase the longitudinal depth and lateral length of the damage.

关键词： Cross angle Damage accumulation Damage radius Interference mechanism Trochoidal feed scratches

Recent progress of residual stress measurement methods: A review

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Chinese Journal of Aeronautics 2021年第2期34卷 54-78页

作者： Jiang GUO Haiyang FU Bo PAN Renke KANG key laboratory for precision and non-traditional machining of ministry of education Dalian University of TechnologyDalian 116024China

Residual stress is one of the main factors affecting the mechanical properties of materials, such as their strength, plasticity and surface integrity. For instance, tensile stress conditions can adversely affect material performance or component life, while compressive stress conditions can improve material fatigue strength. During the processing of integrated aviation structures, machining deformation caused by residual stress has become one of the most prominent manufacturing problems. Therefore, it is very important to measure and evaluate the stress for real *** paper reviews the research of residual stress measurement methods over the past five years by classifying them according to the measurement methods appearing in each stage. The existing problems and difficulties of each measurement technology are summarized, and future trends are forecasted. This paper provides a reference for further in-depth study of residual stress measurement technologies.

关键词： Destructive testing Future trends Measurement nondestructive testing Residual stress

Transformation mechanism of secondary phase and its effect on intergranular corrosion in laser wire filling welding Ni-based alloy/304 stainless steel

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Transactions of nonferrous Metals Society of China 2021年第3期31卷 715-725页

作者： Bo CHENG Dong-jiang WU Chao ZHANG Dong-sheng CHAI Guang-yi MA key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of TechnologyDalian 116024China

To clarify the transformation mechanism of secondary phase and the mechanism of intergranular corrosion in laser welding Ni-based alloy (Hastelloy C-276)/304 stainless steel with filler wire,the secondary phase was analyzed by electron probe micro-analysis (EPMA) and transmission electron microscopy (TEM).The evaluation of intergranular corrosion resistance of the welded joints was conducted by double-loop electrochemical potentiokinetic reactivation(DL-EPR) method,and at the same time the chemical compositions of the corrosion surface were analyzed by energy-dispersive spectrometry (EDS).The results show that p phase has complete coherence relationship withμphase,and the coherent relationship is described as[001]p//■and[430]p//[0001]μ.Theμphase is rapidly transformed from p phase,which is the inhomogeneous phase *** transformation of secondary phase will increase the susceptibility to intergranular ***,the transformation of secondary phase should be avoided in the welding process.

关键词： phase transformation intergranular corrosion secondary phase Ni-based alloy dissimilar metal laser welding

Statistical Description of Debris Particle Size Distribution in Electrical Discharge machining

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 67-72页

作者： JIA Zhenyuan ZHENG Xinyi WANG Fuji LIU Wei key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of Technology Dalian 116023 China

Gap debris as discharge product is closely related to machining process in electrical discharge machining（EDM）. A lot of recent researches have focused on the relationship among debris size, surfaces texture, remove rate, and machining stability. The study on statistical distribution of debris size contributes to the research, but it is still superficial currently. In order to obtain the distribution law of the debris particle size, laser particle size analyzer（LPSA） combined with scanning electron microscope（SEM） is used to analyze the EDM debris size. Firstly, the heating dried method is applied to obtain the debris particles. Secondly, the measuring range of LPSA is determined as 0.5–100 μm by SEM observation, and the frequency distribution histogram and the cumulative frequency distribution scattergram of debris size are obtained by using LPSA. Thirdly, according to the distribution characteristic of the frequency distribution histogram, the statistical distribution functions of lognormal, exponentially modified Gaussian（EMG）, Gamma and Weibull are chosen to achieve curve fitting of the histogram. At last, the distribute law of the debris size is obtained by fitting results. Experiments with different discharge parameters are carried out on an EDM machine designed by the authors themselves, and the machining conditions are tool electrode of red-copper material, workpiece of ANSI 1045 material and working fluid of de-ionized water. The experimental results indicate that the debris sizes of all experiment sample truly obey the Weibull distribution. The obtained distribution law is significantly important for all the models established based on the debris particle size.

关键词： electrical discharge machining debris particle measurement size distribution curve fitting

Characteristics Prediction Method of Electro-hydraulic Servo Valve Based on Rough Set and Adaptive Neuro-fuzzy Inference System

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Chinese Journal of Mechanical Engineering 2010年第2期23卷 200-208页

作者： JIA Zhenyuan MA Jianwei WANG Fuji LIU Wei key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of Technology Dalian 116024 China

Synthesis characteristics of the electro-hydraulic servo valve are key factors to determine eligibility of the hydraulic production. Testing all synthesis characteristics of the electro-hydraulic servo valve after assembling leads to high repair rate and reject rate, so accurate prediction for the synthesis characteristics in the industrial production is particular important in decreasing the repair rate and the reject rate of the product. However, the research in forecasting synthesis characteristics of the electro-hydraulic servo valve is rare. In this work, a hybrid prediction method was proposed based on rough set（RS） and adaptive neuro-fuzzy inference system（ANFIS） in order to predict synthesis characteristics of electro-hydraulic servo valve. Since the geometric factors affecting the synthesis characteristics of the electro-hydraulic servo valve are from workers＇ experience, the inputs of the prediction method are uncertain. RS-based attributes reduction was used as the preprocessor, and then the exact geometric factors affecting the synthesis characteristics of the electro-hydraulic servo valve were obtained. On the basis of the exact geometric factors, ANFIS was used to build the final prediction model. A typical electro-hydraulic servo valve production was used to demonstrate the proposed prediction method. The prediction results showed that the proposed prediction method was more applicable than the artificial neural networks（ANN） in predicting the synthesis characteristics of electro-hydraulic servo valve, and the proposed prediction method was a powerful tool to predict synthesis characteristics of the electro-hydraulic servo valve. Moreover, with the use of the advantages of RS and ANFIS, the highly effective forecasting framework in this study can also be applied to other problems involving synthesis characteristics forecasting.

关键词： characteristics prediction rough set adaptive neuro-fuzzy inference system electro-hydraulic servo valve,artificial neural networks

machining the Integral Impeller and Blisk of Aero-Engines:A Review of Surface Finishing and Strengthening Technologies

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Chinese Journal of Mechanical Engineering 2017年第3期30卷 528-543页

作者： Youzhi Fu Hang Gao Xuanping Wang Dongming Guo key laboratory for precision and non-traditional machining technology of ministry of education dalian university of technologyDalian 116024China

The integral impeller and blisk of an aero-engine are high performance parts with complex structure and made of difficult-to-cut materials. The blade surfaces of the integral impeller and blisk are functional surfaces for power transmission, and their surface integrity has signif- icant effects on the aerodynamic efficiency and service life of an aero-engine. Thus, it is indispensable to finish and strengthen the blades before use. This paper presents a comprehensive literature review of studies on finishing and strengthening technologies for the impeller and blisk of aero-engines. The review includes independent and inte- grated finishing and strengthening technologies and dis- cusses advanced rotational abrasive flow machining with back-pressure used for finishing the integral impeller and blisk. A brief assessment of future research problems and directions is also presented.

关键词： Integral impeller and blisk Aero-engine Surface integrity Surface finishing Surface strengthening

Material removal rate in chemical-mechanical polishing of wafers based on particle trajectories

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Journal of Semiconductors 2010年第5期31卷 145-150页

作者：苏建修陈锡渠杜家熙康仁科 Henan Institute of Science and technology key laboratory for precision and non-traditional machining of ministry of education Dalian University of Technology

Distribution forms of abrasives in the chemical mechanical polishing（CMP） process are analyzed based on experimental *** the relationships between the wafer,the abrasive and the polishing pad are analyzed based on kinematics and contact *** to the track length of abrasives on the wafer surface,the relationships between the material removal rate and the polishing velocity are *** analysis results are in accord with the experimental *** conclusion provides a theoretical guide for further understanding the material removal mechanism of wafers in CMP.

关键词： chemical mechanical polishing material removal mechanism abrasive material removal rate