Table of Content

10 September 2018, Volume 29 Issue 17

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Control of Engines Equipped with Electromagnetic Valvetrains in Shifting Processes

CHEN Huitao;CHANG Siqin;FAN Aimin

2018, 29(17):  2017-2022. 

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To realize the applications of EMVT, a control-oriented mean value model of engines with EMVTs was established. A controller of EMVT was designed, which realized that the air flow was regulated by controlling the intake valve motions directly for controlling the rotational speeds and torques of engines. Then, for improving shift quality and shortening shift time of AMT in shifting processes , a control strategy was proposed for engine torques and rotational speeds based on clutch transmitted torques. The effectivenesses of the EMVT controllers and the control strategy in shifting processes were verified by simulations carried out in MATLAB/Simulink.

Research Status and Perspectives of ELID Grinding Oxidation Films

WU Qiaoping1,2;ZHENG Weijia1;DENG Zhaohui1,2;ZHAO Heng2

2018, 29(17):  2023-2030. 

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The oxidation films formed on the surfaces of wheels played an important role in the grinding performance during the ELID grinding processes, which might prevent further electrolysis and avoid excessive wear of the grinding wheels. And the oxidation film could accommodate a large number of abrasive particles that were dropped due to electrolysis, this made wheel grinding just like the polishing of free abrasive particles, which was beneficial to improve the grinding surface quality. The properties of oxidation film directly affected the grinding efficiency and surface quality of ELID grinding. This paper mainly introduced the formation and characterization of the oxidation films, physical and chemical properties of the oxidation films and influence factors of oxidation film formation. And the next steps of the researches of the oxidation films in ELID grinding were prospected.

Tooth Surface Form Error Correction for Face Gear Grinding

MING Xingzu1,2;FANG Shuguang2;WANG Hongyang2

2018, 29(17):  2031-2037. 

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The form errors of the face gear tooth surfaces were taken as the research object, the mathematical model of face gear tooth surfaces was established,and the error measurements of face gear tooth surfaces were conducted by CMM. In order to improve the accuracy of face gear tooth surfaces and enhance the application values of theory and engineering, an error assessment method of face gear tooth surfaces was proposed based on SQP. With the identification equation of the tooth surface errors was established, the processing parameters of the machine tools were optimized by using SQP algorithm. And compared with the least squares optimization method, the modified machine tool adjustment parameters were applied, the modified tooth surface errors were detected by CMM again, which verified the feasibility of the method.

Tool Wear Condition Recognition Based on SDAE

WANG Lihua1;YANG Jiawei1;ZHANG Yonghong1;ZHAO Xiaoping2;XIE Yangyang1

2018, 29(17):  2038-2045. 

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A new method of condition recognition for tool wear was proposed based on SADE . A SDAE neural network was constructed to learn the characteristics of AE signals, and a supervised fine-tuning of the autoencoder network was carried out, so that the tool wear conditions were accurately recognized. The experimental results show that the SDAE method may learn adaptively to get effective feature expressions and the tool wear condition recognition precision is high. The proposed method may be used to recognize tool wear conditions effectively.

Topology Optimum Design Method for Periodic Stiffener Structures Based on Adaptive Growth Method

DONG Xiaohu;DING Xiaohong

2018, 29(17):  2045-2051. 

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Adaptive growth method was applied to topology optimum design for periodic stiffener structures, the minimum strain energy of the structures was taken as the target and the stiffener sectional areas were taken as the design variables, and the topology optimum design model was constructed. In order to ensure the optimize structures might obtain periodic optimal topological form, the periodic constraints were added to the optimization mathematical model and the sensitivity filter function was introduced to solve the problems of numerical instability. The typical engineering structure design examples show that the proposed method may be used to obtain clearly shaped layouts of the stiffener bars in the periodic stiffener structure design, moreover the design efficiency is high and the applicability is wide. Meanwhile, the proposed method was used to simulate the growth of lotus leaf veins, and the layout forms similar to that of natural lotus leaf veins were obtained, which show that the distributions of leaf veins in nature may make the lotus leaf have the maximum overall stiffness under natural loads such as rains and snows.

Design and Optimization of Combined Energy Absorption Devices Based on Free Inversion

LIU Bin1;XIAO Shoune1;ZHU Tao1;YANG Guangwu1;CHE Quanwei2

2018, 29(17):  2052-2059. 

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To study the energy absorption characteristics of the three-section straight-turned tubes under axial compression, the nonlinear finite element software LS-DYNA was used for simulation and analysis. It is found that the force-displacement curve is unified in a very stable horizontal line when the thickness of the upper tube is slightly larger than that of the lower tube, with the product of compression force efficiency up to 0.838 7, SEA equals to 15.342 8 J/g and the stroke efficiency up to 76%, which are close to the theoretical values respectively. Due to the characteristics of high stroke efficiency, smooth force-displacement curve but deficient in SEA, bellows and multicellular tube were filled inside the three-section straight-turn tubes to improve the SEA, whose results show that the combined energy absorption device maintains the characteristics of high stroke efficiency and stable load, while creating an increase by 105.75% in total energy absorption and 26.28% in SEA, comparing with the single three-section straight-turn tubes. Then the radial basis function proxy model and the genetic algorithm were applied to optimize the SEA of the combined energy absorbing devices. Optimization results show that the maximum SEA is obtained with the multicellular tube, bellows taking the upper limit and lower limit of thickness individually； the value increases by 30.86%, comparing with the single three-section straight-turn tubes.

Speed Measurement Method of Hermetic Reciprocating Compressors Based on Discharge Pressure Fluctuations

JIN Huaqiang1,2;GU Jiangping1,2;HUANG Yuejin2;SUN Zhe2;SHEN Xi2

2018, 29(17):  2060-2068. 

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A method was proposed for measuring the speeds of hermetic reciprocating compressors based on discharge pressure pulsations.The suction and discharge valves of the hermetic reciprocating compressors were opened and closed with the reciprocating movements of pistons,resulting in pressure pulsations of compressor suctions and discharges,and the discharge pressure pulsations are more obvious than the suction pressure pulsations.The amplitudes of the pressure pulsations in the discharge chambers are higher than that in discharge pipes,and the speeds of compressor equal to the pressure pulsation frequencies with CZT after detrending.Therefore,the pressures in discharge pipes may be taken as the sampling signals for compressor speed measurements.Under different compression ratios,the speeds measured by this method were compared with the actual rotational speeds of the compressors.Experimental results show the effectiveness of the measuring method herein under different load conditions with the accuracy of ±1 r/min and the measuring time of 1 s.

Optimized Design and Simulation of Wedge Structures for Negative Pressure Chip Removal Devices

DONG Weikang1;GUAN Shixi1;GUO Zhenhao1;LIU Ya2

2018, 29(17):  2069-2072,2086. 

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In order to solve the problems that the large-length-diameter ratios deep-hole machining had difficulty to chip removal, the negative pressure jet model was established on the basis of analyzing the mechanism of DF（double feeder） system‘s negative pressure chip removal. A wedge structure at the jet nozzle was designed to reduce the energy loss in the areas by the method of filling in the partial areass of the front and rear separation zones. Through theoretical calculation and Fluent simulation optimization experiments, the results show that the wedge size is the best when the length is L1 = 75 mm and the width is L2 = 1 mm, which enhances the cutting fluid flow rates by about 10.07%, increases the turbulent kinetic energy by about 11.39%, and reduces the negative pressure values by about 79.26%. The wedge structure enhances the ability of negative pressure chip removal, and reduces the front and rear separation area energy loss maximally.

Optimization Design of Hydraulic Sandblasting Perforators Based on Discrete Phase Model

ZHANG Derong1;WU Simeng1;HUANG Zegui2

2018, 29(17):  2073-2080. 

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In order to solve the problems of erosion wears and short service life of the commonly used hydraulic sandblasting perforators, the erosion wear rules of the commonly used hydraulic sandblasting perforators were analyzed by using the discrete phase model of numerical simulation software. The optimization designs of tool structures and nozzle structures were proposed. And the jet and erosion resistance performances of the new hydraulic sandblasting perforators were verified. The results show that the erosion areas of the commonly used hydraulic sandblasting perforators are mainly concentrated in the tool lumen nozzle inlets , the nozzle inlet flow channels and the tool wall nozzle outlets. Besides, the perforator structures, the perforating fluid characteristics, the pipe column vibrations and the working environments are the four main reasons for the serious erosions of the blasting perforators. Under the same conditions, the jet velocities of new hydraulic sandblasting perforators are larger , the velocity differences between the upper and lower nozzles are smaller, and the anti-erosion performances are better compared to the commonly used ones.

Study on Sawing Characteristics of Band Saw for Metal under Ultrasonic Water Mist

NI Jing;CHEN Yebo;MENG Zhen;FENG Guodong;XU Jing

2018, 29(17):  2081-2086. 

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Aiming at the applications of minimal quantity metal lubrication technology in the sawing processes of  blades of band saw for, an ultrasonic jet spray lubrication system for saw tooth was built, and the cutting tests were carried out under dry cutting, flowing and ultrasonic water mist. The results show that the mean value of the main cutting force Fx is the smallest under the action of ultrasonic water mist, which is 53% Fx under the dry cutting and 31% Fx under the flowing effect. Moreover, the cutting fluid consumption of ultrasonic water mist is smaller, which is only 10% of the consumption of flowing action. As analysis and observation with high speed micro-camera, micron-level droplets are produced on the surfaces of the saw teeth under the ultrasonic water mist. Micro-wetting effects are achieved on the surfaces of the saw teeth. This phenomenon may lead to a smaller wetting angle and better wetting effect. Compared with the dry cutting and flowing action, the chips formed under the action of ultrasonic water mist have a smaller radius of curvature, only 300 μm, which also confirms the conclusion that ultrasonic water mist has the best wetting effect iveness on the saw tooth surfaces.

Vulnerability Assessment Method for Mixed-model Manufacturing Systems Based on UGF

GAO Guibing;YUE Wenhui;OU Wenchu

2018, 29(17):  2087-2093,2099. 

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The state entropy-based method for the assessment of vulnerability in mixed-model manufacturing systems suffered the combinatorial state-space explosion problems, aiming at the shortcomings of this method, a new quantitative assessment method was proposed based on UGF for the vulnerability of mixed-model manufacturing system. Firstly, the UGFs for each manufacturing unit were established by analyzing the states and solving the probabilities,the vulnerability entropies of each unit were defined and calculated, and the vulnerability assessment models of manufacturing units were established. Secondly, based on characteristics of mixed-model manufacturing the system‘s structures and the series-parallel operators of the UGF, a UGF model of mixed-model manufacturing system was solved, and by definition of vulnerability entropy of the mixed-model manufacturing system, the vulnerability assessment model was established based on the critical vulnerability entropy. Finally, taking a typical mixed-model manufacturing system as an example, the proposed method was used to evaluate the vulnerability. Compared with the state entropy-based method, the efficiency of vulnerability assessment may be obviously improved by the proposed method.

Design Method of Predecisional Remanufacturing Based on Life Matching Function

SONG Shouxu;QIU Quan;BU Jian;KE Qingdi

2018, 29(17):  2094-2099. 

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In the processes of predecisional remanufacturing, the key components often had the problems of “early remanufacturing” or “delayed remanufacturing”, the concept of life matching function was put forward. By studying the changes of the predecisional remanufacturing timing of key components under different characteristic parameters, the mapping relationship between the predecisional remanufacturing timing of key components and characteristic structural parameters was established. And the life matching factor was introduced as the sign of life matching. A design method of predecisional remanufacturing was proposed based on life matching function. According to the life matching function, the characteristic structure parameters were optimized to realize the matching of the predecisional remanufacturing timing of the critical parts and the products. Finally, an engine was taken as an example for life matching, and the validity and feasibility of the method were verified.

A Review of On-line Monitoring Techniques in Metal Powder Bed Fusion Processes

ZHAO Dechen1,2,3;LIN Feng1,2,3

2018, 29(17):  2100-2110,2118. 

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The metal powder bed fusion was an advanced and promising manufacturing technique which was rapidly developed in recent years. The extensive attentions in the fields of aerospace, biomedicine and automotive were obtained, but shortcomings such as poor process repeatability and insufficient stability were still restricting its further industrial applications. On-line monitoring provided an effective solution for these obstacles by monitoring process statuses and defects in time. The research statuses of on-line monitoring for metal powder bed fusion were reviewed from the aspects of powder recoating monitoring, powder bed inspection, building process monitoring and deposited layer inspection. Then, limitations of present online monitoring techniques were pointed out, and some topics to be further studied were predicted.

SiC Components via SLS Combined with Reaction Sintering

FU Minhui1;LIU Kai2;LIU Jie1;TAN Yuanliang2

2018, 29(17):  2111-2118. 

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In order to obtain high density, high performance, complex structures of SiC ceramic parts, a mechanical mixing method was proposed to prepare the SiC composite powder which contained phenolic resin binder and curing agent urotropine. The composite powders in SLS formed the ceramic billets, and the ceramic billet sintering atmosphere and siliconizing processing, making it react with matrix sintering, eventually forming a complex ceramic profiled. When the laser power, scanning velocity, scanning spacing, layer thickness are 8 W, 2 000 mm/s,0.1 mm,0.15 mm respectively, the SLS parts have the highest relative density and strength. SLS specimen were degreased and high temperature siliconizing processed reasonably, the bending strength of SiC ceramics sintered parts reached 81 MPa,and the relative density is greater than 86% after high temperature siliconizing process.

Process Simulation and Experiments for PEEK 3D Printing Technology

SHI Changchun1;HU Bin1;CHEN Dingfang2;CHEN Rong3;SHAN Bin1

2018, 29(17):  2119-2124,2130. 

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The medical PEEK components with high performance were difficult to process because they displayed intricate structure. To deal with the problems, the research of PEEK RP was conducted based on the fused deposition modeling （FDM） 3D printing technology. In particular, the design of high temperature chamber, analog simulation and process experiments were carried out accordingly. The simulation results show that the warping deformation phenomenon of PEEK sample may be greatly suppressed obviously through the applications of the prototyping chamber with the temperature close to the glass transition temperature of PEEK . Moreover, PEEK filament may melt uniformly through the applications of the nozzles with smaller diameters, which makes sure that the PEEK filament span steadily. The experimental data show that the highest average tensile strength of PEEK sample achieves about 74.74 MPa when using the nozzle diameter of 4 mm and the layer thickness of 0.1 mm during the PEEK 3D printing processes. The values are close to the tensile strength of the PEEK sample processed through the traditional injection molding.

Development on Key Technologies and Facilities of Integral Die Forging for Motorhomes Steering Knuckles

ZHANG Yunjun1;CHEN Tianfu1;YANG Jie1;HUANG Mingwei1;XIA Juchen2;DENG Lei2;JIN Junsong2

2018, 29(17):  2125-2130. 

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Motorhomes steering knuckles had big dimensions and complicated structures. The split manufacturing technology currently used possessed the problems of low material utilization, low production efficiency, and poor product performance. So an integral die forging was proposed, and the optimization of the processes and the development of special facilities for the bending processes were focused on. With adopting classical plastic forming theory, finite element numerical simulations and physical tests, the stress-strain states, metal flows and damage distributions of the bending processes were analyzed. The results of the processing tests show that the proposed program is reasonable and that the integral die forging may be used instead of split manufacturing.The material utilization rate is increased from 45% to more than 70%, and the production efficiency is improved by 4 to 5 times.

Effects of Mandrel Diameters on Large Deformation Pushing-pulling Necking

WANG Liandong1;LIU Chao1,2;LIU Heng1;WANG Xiaodi3;WANG Zhipeng1

2018, 29(17):  2131-2136. 

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The differences of stresses and deformations with different mandrel diameters were analyzed, through the analyses of the pushing-pulling necking mechanical model. A design method of mandrel diameter was proposed based on the analysis results. The finite element model was established for the first necking processes of 6.5 t bulging-pressing axle housing, and the influences of the mandrel diameters on forming rules were analyzed. A appropriate range of mandrel diameters was given based on the conditions that the tubes were not easy to wrinkle and crack. The experiments of the first pushing-pulling necking processes were carried out on the special equipment, and the forming results with three different mandrel diameters are consistent with that from the finite element simulation.