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Size effects on process performance and product quality in progressive microforming of shafted gears revealed by experiment and numerical modeling

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Advances in Manufacturing 2023年第1期11卷 1-20页

作者： Jun-Yuan Zheng Hui Liu Ming-Wang Fu Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China

As one of the indispensable actuating components in micro-systems,the shafted microgear is in great production *** is a manufacturing process to produce microgears to meet the *** to the small geometrical size,there are uncertain process performance and product quality issues in this production *** this study,the shafted microgears were fabricated in two different scaling factors with four grain sizes using a progressively extrusion-blanking *** explore the unknown of the process,grain-based modeling was proposed and employed to simulate the entire forming *** results show that when the grains are large,the anisotropy of single grains has an obvious size effect on the forming behavior and process performance;and the produced geometries and surface quality are worsened;and the deformation load is *** deformation zones were identified in the microstructures with different hardness and distributions of stress and *** simulation by using the proposed model successfully predicted the formation of zones and revealed the inhomogeneous deformation in the forming *** undesirable geometries of microgears including material unfilling,burr and inclination were observed on the shaft and teeth of gear,and the inclination size is increased obviously with grain *** avoid the formation of inclination and material unfilling,the punch was redesigned,and a die insert was added to constraint the bottom surface of the gear *** new products had then the better forming quality.

关键词： microforming Microprocess performance microforming quality Size effect affected deformation behavior Die design optimization

Key Problems in microforming Processes of Microparts

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Journal of Materials Science & Technology 2007年第2期23卷 283-288页

作者： Chunju WANG Debin SHAN Bin GUO Jian ZHOU Lining SUN School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China Robot Research Institute Harbin Institute of Technology Harbin 150001 China

From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming apparatus with a high stiffness piezoelectric actuator as the punch driver was developed to produce *** improve the forming abilities and locate the billets, a floating microdie was designed. The size effects of the billets and die cavities on the microforming abilities were studied with upsetting and coining tests, *** the isothermal microforming process of microgears was performed with the developed microforming apparatus. Several analysis methods were used to evaluate the forming quality of the microparts.

关键词： microforming Size effects microforming apparatus Floating microdie Microgears

Mechanism of size effects in microcylindrical compression of pure copper considering grain orientation distribution

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Rare Metals 2013年第1期32卷 18-24页

作者： Chuan-Jie Wang Chun-Ju Wang Bin Guo De-Bin Shan Yan-Yan Chang School of Materials Science and Engineering Harbin Institute of Technology Key Laboratory of Micro-Systems and Micro-Structures Manufacturing Harbin Institute of Technology

In microscale deformation, the magnitudes of specimen and grain sizes are usually identical, and size- dependent phenomena of deformation behavior occur, namely, size effects. In this study, size effects in micro- cylindrical compression were investigated experimentally. It was found that, with the increase of grain size and decrease of specimen size, flow stress decreases and inhomogeneous material flow increases. These size effects tend to be more distinct with miniaturization. Thereafter, a modified model considering orientation distribution of surface grains and continuity between surface grains and inner grains is developed to model size effects in micro- forming. Through finite element simulation, the effects of specimen size, grain size, and orientation of surface grains on the flow stress and inhomogeneous deformation were analyzed. There is a good agreement between experimental and simulation results.

关键词： microforming Cylindrical compression Sizeeffects Grain orientation Inhomogeneous deformation

Experimental Investigation on Micro Deep Drawing of Stainless Steel Foils with Different Microstructural Characteristics

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Chinese Journal of Mechanical Engineering 2021年第2期34卷 179-189页

作者： Jingwei Zhao Tao Wang Fanghui Jia Zhou Li Cunlong Zhou Qingxue Huang Zhengyi Jiang College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment Ministry of EducationTaiyuan 030024China TYUT-UOW Joint Research Center Taiyuan University of TechnologyTaiyuan 030024China TYUT-UOW Joint Research Center University of WollongongWollongongNSW 2522Australia School of Mechanical MaterialsMechatronic and Biomedical EngineeringUniversity of WollongongWollongongNSW 2522Australia Shanxi Provincial Key Laboratory on Metallurgical Device Design and Theory Taiyuan University of Science and TechnologyTaiyuan 030024China

In the present work,austenitic stainless steel(ASS)304 foils with a thickness of 50μm were first annealed at temperatures ranging from 700 to 1100℃for 1 h to obtain different microstructural *** the effects of microstructural characteristics on the formability of ASS 304 foils and the quality of drawn cups using micro deep drawing(MDD)were studied,and the mechanism involved was *** results show that the as-received ASS 304 foil has a poor formability and cannot be used to form a cup using *** wrinkling problem occurs on the drawn cup,and the height profile distribution on the mouth and the symmetry of the drawn cup is quite non-uniform when the annealing temperature is 700℃.At annealing temperatures of 900 and 950℃,the drawn cups are both characterized with very few wrinkles,and the distribution of height profile,symmetry and mouth thickness are uniform on the mouths of the drawn *** wrinkling becomes increasingly significant with a further increase of annealing temperature from 950 to 1100℃.The optimal annealing temperatures obtained in this study are 900 and 950℃for reducing the generation of wrinkling,and therefore improving the quality of drawn *** non-optimized microstructure,the distribution of the compressive stress in the circumferential direction of the drawn foils becomes inhomogeneous,which is thought to be the cause of the occurrence of localized deformation till wrinkling during MDD.

关键词： microforming Micro deep drawing Stainless steel foils Wrinkling Annealing Microstructure

Metal flow hysteresis behavior and shape control strategy during porthole die extrusion of micro heat pipe

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Chinese Journal of Aeronautics 2023年第7期36卷 268-281页

作者： Yongda LIU Jie XU Xiaoliang WANG Debin SHAN Bin GUO Key Laboratory of Micro-Systems and Micro-Structures Manufacturing of Ministry of Education Harbin Institute of TechnologyHarbin 150080China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

The shape control strategy of micro grooves is still unclear and challenging during the porthole die extrusion of grooved micro heat pipe(MHP).Through the simulation and experiment of porthole die extrusion of a MHP profile,the metal flow hysteresis behavior within micro features and the effect of ram speed and extrusion temperature on it and the resulting forming integrity was ***,Taguchi design and variance analysis(ANOVA)were introduced to determine their influence magnitude on the metal flow uniformity calculated by simulation *** main findings are given *** metal flow hysteresis derives from part feature size *** negligible friction-affected area during conventional extrusion severely slows down the metal flow within micro features during the MHP profile extrusion,which is due to the surge in the area ratio of the friction-affected area to the region in which it is *** ram speed nor extrusion temperature can change the distribution of the friction-affected ***,increasing ram speed multiplies the metal flow hysteresis and severely reduces the forming integrity,whereas extrusion temperature has little *** this strategy,batch extrusion of the profile with microgrooved width of 0.27±0.02 mm was achieved in industrialized conditions.

关键词： Micro heat pipe microforming Size effect Porthole die extrusion Metal flow Forming integrity Microstructure

Performance characterization of Bi_2O_3/Al nanoenergetics blasted micro-forming system

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Defence Technology（防务技术） 2019年第1期15卷 98-105页

作者： Vinay Kumar Patel Rishi Kant Anu choudhary Madhusudan Painuly Shantanu Bhattacharya Department of Mechanical Engineering Govind Ballabh Pant Institute of Engineering & Technology Pauri-Garhwal Department of Mechanical Engineering Indian Institute of Technology Kanpur

This paper reports a novel micro-blast driven manufacturing process for micro-forming of Aluminum foils. The micro-blast is realized by using a nanoenergetic material system comprising of Bi_2O_3 microrods and aluminum particles. There is an enhanced need of forming of thin aluminum foil structures in small regions from point of view of drug packaging etc. The process developed caters to this need by using a single shot forming process using a micro-blast source. The micro-blast that is generated from an energetic composite system is made highly tunable by modulating the peak pressure generated through the blasting process and their impact in micro-forming of thin aluminum foils is observed through parametric studies. The engineering challenge involved in these experiments is to tune the blast pressure properties in order to address the forming of thin metal sheets with limiting boundary values as defined by the failure criteria. A variety of characterization techniques related to a thorough analysis of the synthesized material viz. X-ray diffraction(XRD), Scanning Electron Microscopy(SEM) etc, are used to tune the functional properties like gauge blast pressure etc, of material system. We have found a material system that can generate a maximum peak pressure of 73.8 MPa with pressurization rate of 2460 GPas^(-1) and that is able to accomplish micro-forming on thin metal foils(around 0.3 mm thickness). Experimental investigations demonstrate that tunabilty aspect of the energetic composites when exercised can enable variant processes such as embossing, coining, drilling etc. which may be of significant utility to drug packaging industries. A proper mathematical modeling of the forming process and critical process parameters therein have also been detailed.

关键词： microforming Aluminum Foil Bi2O3 Nanoenergetic Tunability Process parameters

Flow stress and tribology size effects in scaled down cylinder compression

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Transactions of Nonferrous Metals Society of China 2009年第S02期19卷 516-520页

作者： GUO Bin GONG Feng WANG Chun-ju SHAN De-bin School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Micro-Systems and Micro-Structures Manufacturing Ministry of EducationHarbin Institute of TechnologyHarbin 150080China

microforming is an effective method to manufacture small metal ***,macro forming can not be transferred to microforming directly because of size *** stress and tribology size effects were *** down copper T2 cylinder compression was carried out with the lubrication of castor oil and without *** results show that the flow stress decreases with decreasing the initial specimen diameter in both lubrication conditions,and the flow stress decreases by 30 MPa with the initial specimen diameter decreasing from 8 mm to 1 *** friction factor increases obviously with decreasing the initial specimen diameter in the case of lubricating with castor oil,and the friction factor increases by 0.11 with the initial specimen diameter decreasing from 8 mm to 1 ***,the tribology size effect is not found in the case without *** reasons of the flow stress and tribology size effects were also discussed.

关键词： microforming size effects flow stress friction factor cylinder compression

Fatigue crack growth of titanium alloy joints by electron beam welding

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Rare Metals 2014年第5期33卷 516-521页

作者： Hong-Yu Qi Hao Shi Shao-Lin Li Xiao-Guang Yang School of Jet Propulsion Beijing University of Aeronautics and Astronautics

Electron beam welding（EBW） has been widely used in the manufacture of titanium alloy welded blisk for aircraft engines. Based on fatigue crack growth tests on titanium alloy electron beam welding（EBW） joints, mechanism of fracture was investigated under scanning electron microscope（SEM）. The results show that fatigue crack growth rate increases as the experimental load increases under the same stress ratio and stress intensity factor range. At the beginning of crack growth, the extension mechanism of fatigue crack is the typical mechanism of cleavage fracture. In the steady extention stage, crack extends along the weld seam ***, crack growth direction changes to extend along the base metal. The extension mechanism of fatigue crack in the weld seam is the main mechanism of cleavage fracture and the extension mechanism of fatigue crack in the base metal is the main extension mechanism of fatigue band. In the instantaneous fracture stage, the extension mechanism of fatigue crack is the typical dimple-type static fracture *** growth was simulated by conventional finite element method and extended finite element method.

关键词： microforming Ti–6Al–4V alloy Electron beam welding Fatigue crack growth Fracture analysis

Feasibility evaluation of failure models for predicting forming limit of metal foils

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Chinese Journal of Aeronautics 2020年第9期33卷 2461-2471页

作者： Bao MENG Jiejie SHI Yiyun ZHANG Cheng CHENG Bolin MA Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100083China

Forming limit of metal foil is an important index to evaluate its formability,and is of considerable significance to improve the quality of *** ductile fracture(DF)behavior in microscale plastic deformation is remarkably affected by the geometry and grain *** explore the size-dependent forming limit curve(FLC),the Holmberg and Marciniak tests of SUS304 foils with the thicknesses of less than 0.1 mm and diverse grain sizes were *** addition,the validity and feasibility of three types of existing failure models including Swift/Hill,MarciniakKuczynski(M-K)and DF criteria for predicting the micro-scaled FLCs were *** is found that the Swift/Hill model possesses the worst accuracy with predicting deviation above 50%.Four classical DF criteria including Freudenthal,Ayada,Brozzo and Oh show great difference,and Oh model considering plastic anisotropy presents the best *** predicted deviation of M-K model is aggravated with increasing grain size and decreasing foil thickness,which is attributed to the intensified free surface roughening and transformation of fracture mechanism with *** research thus provides a deeper understanding and valuable reference for the widespread application of FLC in microforming.

关键词： Failure criteria Forming limit Metal foil microforming Size effect