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A novel method of water bath heating assisted small ball-end magnetorheological polishing for hemispherical shell resonators

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Chinese Journal of Aeronautics 2023年第12期36卷 451-460页

作者： Jinchuan TIAN mingjun chen Jian chenG Henan LIU State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

Hemispherical shell resonator(HSR)is the core component of hemispherical resonator *** is aφ-shaped small-bore complex component with minimum curvature radius less than 3 ***,traditional polishing methods are difficult to polish *** ball-end magnetorheological polishing method can polish the small components with complicated three-dimensional surface and obtain non-destructive ***,this method is suitable for polishing ***,the material removal rate of the ordinary small ball-end magnetorheological polishing is low,leading to long polishing time and low output of *** solve this problem,a water bath heating assisted small ball-end magnetorheological polishing method is proposed in this *** influence rule of processing parameters on the material removal rate is studied experimentally.A set of optimal processing parameters is obtained to maximize the material removal *** with the ordinary method,the material removal rate of the new method can be improved by 143%.Subsequently,an HSR is polished by the new *** results show that the polishing time can be reduced by 55%,and the polished surface roughness can reach 7.7 *** new method has the great potential to be used in actual production to improve the polishing efficiency of HSR.

关键词： Hemispherical shell resonator Magnetorheological fluid temperature Material removal rate Optimization Small ball-end magnetorheological polishing

Interference and grinding characteristics in ultra-precision grinding of thin-walled complex structural component using a ball-end grinding wheel

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Chinese Journal of Aeronautics 2021年第4期34卷 192-207页

作者： Tingzhang WANG Henan LIU Chunya WU Jian chen mingjun chen Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels,interference is easy to *** to screw theory and grinding kinematics,a mathematical model is established to investigate the interference and grinding characteristics of the ball-end *** relationship between grinding wheel inclination angle,C axis rotation angle,grinding position angle and grinding wheel wear are *** the grinding wheel inclination angle increases,the C axis rotatable range decreases and the grinding position angle *** grinding position angle and wheel radius wear show a negative correlation with the C axis rotation ***,a trajectory planning criteria for increasing grinding speed as much as possible under the premise of avoiding interference is proposed to design the grinding *** grinding point distribution on the ball-end wheel is calculated,and the grinding characteristics,grinding speed and maximum undeformed chip thickness,are ***,a complex structural component can be ground without interference,and surface roughness and profile accuracy are improved to 40.2 nm and 0.399 lm,compared with 556 nm and 3.427 lm before ultra-precision *** mathematical model can provide theoretical guidance for the analysis of interference and grinding characteristics in complex components grinding to improve its grinding quality.

关键词： Ultra-precision grinding Complex component Ball-end grinding wheel Interference Grinding characteristics

Multiscale simulation of nanometric cutting of single crystal copper——effect of different cutting speeds

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Acta Metallurgica Sinica(English Letters) 2009年第6期22卷 440-446页

作者： Hongmin PEN Qingshun BAI Yingchun LIANG mingjun chen School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China

A multiscale simulation has been performed to determine the effect of the cutting speed on the deformation mechanism and cutting forces in nanometric cutting of single crystal copper. The multiscale simulation model, which links the finite element method and the molecular dynamics method, captures the atomistic mechanisms during nanometric cutting from the free surface without the computational cost of full atomistic simulations. Simulation results show the material deformation mechanism of single crystal copper greatly changes when the cutting speed exceeds the material static propagation speed of plastic wave. At such a high cutting speed, the average magnitudes of tangential and normal forces increase rapidly. In addition, the variation of strain energy of work material atoms in different cutting speeds is investigated.

关键词： Multiscale simulation Nanometric cutting Single crystal copper Propagation speed of plastic wave

On-machine Precision Preparation and Dressing of Ball-headed Diamond Wheel for the Grinding of Fused Silica

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Chinese Journal of Mechanical Engineering 2013年第5期26卷 982-987页

作者： chen mingjun LI Ziang YU Bo PENG Hui FANG Zhen Center for Precision Engineering Harbin Institute of technology The 26th Research Institute China Electronics Technology Group Corporation

In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter,the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode *** on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge *** using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed *** obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear.A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension *** effect of electrode tool wear is investigated by electrical dressing experiments,and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K’ tends to be constant with the increasing of the feed length of electrode and the mean value of K’ is *** experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing *** experimental results show that the surface roughness of the finished workpiece is 0.03 μ*** effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface *** research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica,which provides a solution to the tool setting method and the effect of electrode tool wear.

关键词： precision preparation electrical discharge dressing ball-headed diamond wheel fused silica

Theoretical and Experimental Research on Error Analysis and Optimization of Tool Path in Fabricating Aspheric Compound Eyes by Precision Micro Milling

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Chinese Journal of Mechanical Engineering 2014年第3期27卷 558-566页

作者： chen mingjun XIAO Yong TIAN Wenlan WU Chunya CHU Xin Center for Precision Engineering Harbin institute of technology

Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes （ACEs） are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye （ACE） with surface roughness （Ra） below 0.12 p.m is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.

关键词： aspheric compound eyes (ACEs) micro milling tool path optimization

Magnetorheological finishing of an irregular-shaped small-bore complex component using a small ball-end permanent-magnet polishing head

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Nanotechnology and Precision Engineering 2019年第3期2卷 125-129页

作者： Henan Liu Jian cheng Tingzhang Wang mingjun chen School of Mechatronics Engineering Harbin Institute of Technology

A novel magnetorheological finishing(MRF)process using a small ball-end permanent-magnet polishing head is proposed,and a four-axes linkage dedicated MRF machine tool is fabricated to achieve the nanofinishing of an irregularψ-shaped small-bore complex component with concave surfaces of a curvature radius less than3 *** processing method of the complex component is *** simulation during the entire finishing path is carried out to analyze the material removal characteristics.A typicalψ-shaped small-bore complex component is polished on the developed device,and a fine surface quality is obtained with surface roughness Raof 0.0107μm and surface accuracy of the finished spherical surfaces of 0.3320μm(PV).These findings indicate that the proposed MRF process can perform the nanofinishing of a kind of small-bore complex component with small-curvature-radius concave surfaces.

关键词： Complex component Magnetorheological finishing Magnetostatic simulation Small curvature radius

The Critical Roles of the Gas Flow in Fabricating Polymer Nanofbers:A Mini‑review

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Advanced Fiber Materials 2022年第2期4卷 162-170页

作者： Chao Zhang mingjun chen Haoyi Li Weimin Yang Jing Tan College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China Taiyuan Research Institute China Coal Science and Technology GroupTaiyuan 030000China

Polymer nanofbers attract more and more attention from academia and industry continuously due to their desirable properties,including high specifc surface area,high porosity,and numerous chemically-active surface groups on the fber *** fow was widely adopted to fabricate nanofbers such as solution blown,melt blown,gas fow-assisted melt electrospinning,and bubble ***,a comprehensive review covered the roles that gas fow played in fabricating nanofbers,and their mechanism has not been analysed *** review classifes the roles of gas fow into jet initialization,jet stretching,increasing production,surface modifcation,and inhibition of thermal degradation,to deepen the understanding of gas fow during nanofber *** mechanism of gas fows in the above felds is reviewed in detail.

关键词： Gas fow Nanofber Electrospinning

Research on the influence of machining introduced sub-surface defects and residue stress upon the mechanical properties of single crystal copper

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Science China(Technological Sciences) 2010年第12期53卷 3161-3167页

作者： chen mingjun, XIAO GaoBo, chen JiaXuan & WU ChunYa Harbin Institute of Technology, Harbin 150001, China 1. Harbin Institute of Technology Harbin 150001 China

Large scale molecular dynamics simulations of nanomachining and stretching of single crystal copper are performed to analyze the machining process’ influence on the material’s mechanical properties. The simulation results show that the machining process will introduce interfacial defects inside the specimen and enhance the compressive stress beneath the surface. Gener- ally speaking, interfacial defects lead to the decrease of the strength limit, while residue compressive stress can enhance the elastic limit and even the strength limit. Various machining parameters are adopted to investigate their influence on the me- chanical behavior of machined specimen. Lower cutting speed and smaller cutting depth lead to less defects and greater residue compressive stress, which brings about better mechanical properties. The elastic limit increases by 36.8% under the cutting depth of 0.73 nm and decreases by 21.1% under the cutting depth of 1.46 nm. The strength limit increases by 7.7% under the cutting speed of 100 m/s and decreases by 28.2% under the cutting speed of 300 m/s.

关键词： nanomachining deformation residue stress molecular dynamics dislocations

Experimental and modeling study of surface topography generation considering tool-workpiece vibration in high-precision turning

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Chinese Journal of Aeronautics 2023年第7期36卷 194-212页

作者： Xingying ZHOU Henan LIU Tianyu YU Ruiyang GUO Guangzhou WANG Yazhou SUN mingjun chen State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China

High-precision turning(HPT)is a main processing method for manufacturing rotary high-precision components,especially for metallic ***,the generated vibration between tool tip and workpiece during turning may seriously deteriorate the surface ***,exploring the effect of vibration on turning surface morphology and quality of copper parts using 3D surface topography regeneration model is crucial for predicting HPT *** developed model can update the machined surface topology in real *** this study,the effects of tool arc radius,feed rate,radial vibration,axial vibration and tangential vibration on the surface topography and surface roughness were *** results show that the effect of radial vibration on surface topography is greater than that of axial vibration and tangential *** radial vibration frequency is also *** vibration frequency changes,the surface topography profile presents three different types:the standard sinusoidal curve,the sinusoidal curve whose lowfrequency signal envelopes high-frequency signal,and the oscillation curve whose low-frequency signal superimposes high-frequency *** addition,HPT experiment was carried out to validate the developed *** surface roughness obtained in the experiment was Ra=53 nm,while the roughness obtained by the simulation was Ra=46 nm,achieving a prediction accuracy of 86.7%.Received 4 September 2022;revised 3 October 2022;accepted 17 October 2022.

关键词： High-precision turning Machining vibration Modeling Surface roughness Surface topography