Table of Content

25 April 2022, Volume 33 Issue 08

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Design of Soft Robots for Hand Function Rehabilitation Training

CONG Ming, BI Cong, WANG Minghao, LIU Dong, DU Yu

2022, 33(08):  883-889.  DOI: 10.3969/j.issn.1004-132X.2022.08.001

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In order to solve the problems such as poor fit between soft robot and human hand， insufficient DOF and low driving force， a kind of soft robot with bi-directional bending module and elongation module was designed， which might realize independent or coupled motions of multiple DOF. Using FEM analysis， a soft driver model was established and a variety of flexible materials were fused to ensure that might provide sufficient driving forces. The sensors were used to track the bending characteristics. Experimental results verify that the soft robots may complete grip training and gesture training， etc.， and meet the training requirements of patients at different rehabilitation stages. The fingertip force may reach 5.1 N， and it may play an auxiliary role in the daily hand rehabilitation training of patients. 

Simulation and Experimental Study of Steady-state Temperature Field of  Plastic Gears under Grease Lubrication Conditions#br#

YU Guoda, LIU Huaiju, LU Zehua, WEI Peitang

2022, 33(08):  890-898，907.  DOI: 10.3969/j.issn.1004-132X.2022.08.002

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In order to predict the steady-state temperature of plastic gears under grease lubrication conditions， a finite element numerical model of plastic gear operating temperature field was established based on the temperature-modulus effect and the friction heat flux-hysteresis heat flux multi heat source effect. The distribution of plastic gear steady-state temperature field and the influences of load and speed levels on steady-state temperature were studied. The results show that the temperature of steady-state temperature field decreases gradually along the normal direction of the tooth profiles， and the temperature in the depth of 0.5 mm in the inner normal direction is about 90% of the surface temperature， and the steady-state temperature increases with the increasing of loads or speeds gradually. And the operating temperature tests of POM-POM gear pairs were carried out under grease lubrication conditions and the test results are in good agreement with the simulation ones. This study may pave way to the transmission design of heavy-loading plastic gears. 

Study on Microwave Sintering Technology of Complex-shaped Ceramic Tools

YIN Zengbin, ZHU Zhiyong, WANG Zixiang, YUAN Juntang

2022, 33(08):  899-907.  DOI: 10.3969/j.issn.1004-132X.2022.08.003

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The complex-shaped ceramic tools were efficiently prepared by microwave sintering. The effects of loading mode of samples on distribution of microwave electric field and temperature field were studied by simulation， and the influences of different loading modes on relative density， mechanics properties and microstructure of samples were studied by experiments. Cutting performances of the complex-shaped ceramic tools were also investigated. The results show that when samples are placed horizontally and at the center of the microwave sintering cavity， the electric fields are uniform and the temperature differences are small， that is beneficial to reach full density simultaneously for several samples. The complex-shaped Al2O3/SiC composite ceramic tools prepared by microwave sintering have the integrated cutting edge and show better cutting performance. Compared with the traditional flat rake face ceramic tools， the material removal of complex-shaped ceramic tools are increased 2 times and the machined surface roughness is decreased by about 33%. “Structure-performance” integrated manufacturing technology of complex-shaped ceramic tools based on microwave sintering has broad application prospects. 

Performance Analysis for Discoid Springs and Components of Linear Compressors

CHEN Hongyue, ZHANG Zhanli, LIU Xianyang, CHEN Hongyan, HUANG Xinyu, WEI Yajing

2022, 33(08):  908-914.  DOI: 10.3969/j.issn.1004-132X.2022.08.004

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The existing leaf springs for compressors, which were used in a large number, had low stiffness, so a discoid spring was designed. Stiffness performance of discoid springs and flexible leaf springs were compared by FEM(finit element melhod), and 3 arm shapes with better performance were chosen from 8 different arm shapes of discoid springs. 9 different layout modes of the spring group were analyzed and it is found that the discoid spring placed between two flexible leaf springs with equal thickness show better performance. Response surface objective optimization method was used to optimize the distance of the springs in spring groups. After optimization, the radial stiffness is increased as 37.5%. The stiffness of the optimized spring group were tested and compared with the FEM results. 

Experimental Study of Failure Mechanism of Cylindrical Lithium-ion Batteries under Different Compression Loadings

DONG Sijie, ZHANG Xinchun, WANG Yulin, LIU Nannan, CHEN Xuejin

2022, 33(08):  915-920，951.  DOI: 10.3969/j.issn.1004-132X.2022.08.005

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 To meet the requirements of crashworthiness design of electric vehicle power battery packs， the failure mechanism of lithium-ion batteries was studied under different mechanical abuse conditions. Based on local indentation and plane compression loading tests on three different capacity NCR18650 cylindrical lithium-ion batteries， the force-electric-thermal responses of lithium-ion batteries were analyzed and the cross-section failure modes of the compressed battery samples were given. Then the effects of loading types and battery capacity on the failure mechanism of cylindrical batteries were discussed. The results show that internal short circuit and external short circuit failure modes of batteries may be caused by local indentation and plane compression， respectively. With the increase of battery capacity， the bearing performances of the batteries may reduce， which leads to the failure displacements decrease. Loading types and rated capacity also have an effect on the surface temperature changes of the batteries. The maximum surface temperature of the batteries after the local indentation is higher， and the surface temperature changes of the medium-capacity batteries are relatively smooth. 

Automatic Recognition for Cavity Machining Features of Corner Box Parts Based on Improved Graph Matching#br#

ZHANG Shengfang, WANG Guoqing, MA Fujian, LIU Yu, YANG Dapeng, SHA Zhihua

2022, 33(08):  921-928.  DOI: 10.3969/j.issn.1004-132X.2022.08.006

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To meet the requirements of cavity feature recognition for corner box parts， an automatic cavity feature recognition method was proposed based on improved graph matching. The cavity features of corner box parts were analyzed and the common template attributes of feature simplified model were extracted. The raster height point cloud data of the model was obtained， and the median height was taken as the threshold value to transform it into a 0-1 matrix. The projection eigenvalues of the cavity surfaces were extracted from the 0-1 matrix to separate and recognize the cavity wall and edge surfaces. Face adjacency attribute was used to search the side wall surface of the cavity， and the complete machining features of the cavities were finally identified， including the bottom surface set， the wall side surface set and the side wall surface set. The results of example verification show that the proposed method is more efficient and robust than those of the fixed template matching method to identify the machining features of the cavity of corner box parts. 

Research Progresses of Modeling and Optimization Methods for Multi Domain Behavior Processes of Human-Machine Environmental Systems#br#

DONG Yuanfa, ZHANG Wenli, XIAO Renbin, TIAN Qihua, DU Xuan,

2022, 33(08):  929-942.  DOI: 10.3969/j.issn.1004-132X.2022.08.007

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 Due to the immaturity of intelligent technology in universality， robustness and security， intelligent interactive products were prone to “behavior conflict” due to the mismatch with user behavior patterns in intention expression， information processing， decision logic， interaction timing and action intensity. Unified modeling and optimization of multi domain behavior processes of human-machine environmental systems were the key to realize behavior characteristic regulation and forward design of intelligent interactive products. This paper systematically reviewed the research progresses of multi domain behavior process representation model， modeling language and tool， model validation and behavior process optimization of human-machine environmental systems from four dimensions：how to represent， what to represent， how to verify and how to optimize. The existing problems and limitations in this field were analyzed， and the future research focus and development trend were prospected. 

Key Technologies and Development Trends of Multi-axis Tool Grinding Software

LI Guochao, BAI Xiaoxiang, WANG Liming, LI Changming, LI Yousheng

2022, 33(08):  943-951.  DOI: 10.3969/j.issn.1004-132X.2022.08.008

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Multi-axis tool grinding software for complex-shaped tools become one of the bottlenecks needed to break through by manufacturing industries in China. Therefore， the application scenarios and requirements of tool grinding software were introduced， and the main tool grinding software brands abroad and their functional characteristics were summarized. And the key technologies to be broken through in tool grinding software were analyzed from the perspective of key theoretical problems involved in mathematics， mechanics， material science and other software. Then， the intelligent development trends of tool grinding software in the future were proposed， which may provide references for the independent research and development of tool grinding software in China. 

Laser Ultrasonic Quantitative Detection of Buried Depth for Internal Defects  in Additive Manufacturing Parts#br#

TIAN Xuexue, ZHAO Jiyuan, LU Bingheng, WANG Lei

2022, 33(08):  952-959.  DOI: 10.3969/j.issn.1004-132X.2022.08.009

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A quantitative detection method for the buried depth of internal defects was proposed for the detection of internal defects in additive manufacturing parts. The wavelet packet decomposition technology was used to separate and extract the ultrasonic longitudinal waves in the signals received by the laser ultrasonic nondestructive testing technology, which solvesd the problems that the coupling of ultrasonic surface wave and longitudinal wave affected the time-domain feature extraction. According to the changes of the longitudinal wave sound path of the defects during the detection processes, the quantitative detection of the buried depth of the internal defects in the precision forging samples was realized, and the relative error of the tests is 1.81%. An abnormal point filtering algorithm was added on the basis of the original detection method, and it was applied to the detection of internal defects of manufacturing additive parts with the relative error of detection of 1.76%.

Layer Thickness for SLM of 3D Printed AlSi10Mg Alloys

2022, 33(08):  959-964.  DOI: 10.3969/j.issn.1004-132X.2022.08.010

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Based on three processing parameter combinations of optimized layer thickness, the influences of processing parameter combinations on the basic properties of AlSi10Mg alloy samples printed by SLM was analyzed. In samples of the three processing parameter combinations, hardness is more than 63HRB, wear loss of per area is below 1.5×10-5 g/(s·mm2), porosity is below 0.05%, tensile strength is higher than 440 MPa, and dimensional errors are within ± 0.1 mm. Surface roughness Ra of the upper surface is less than 4 μm, and surface roughness Ra of the side surface is less than 5 μm. The surface quality of the samples printed by the layer thickness 30 μm is the best.

Asymmetric Risk Injection Molding Product Size Prediction Model Based on LightGBM#br#

LIU Yongxing, TANG Xiaoqi, ZHONG Jinglong, ZHONG Zhenyu, ZHOU Xiangdong

2022, 33(08):  965-969.  DOI: 10.3969/j.issn.1004-132X.2022.08.011

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 Due to the influences of environmental instability factors such as temperature and air pressure during the injection molding processes， the processing parameters were changed during the molding processes， resulting in a decrease in product accuracy， product degradation or scrap. Aiming at the problems of similar environmental instability factors， using the data in the molding processes to predict the sizes of injection molding was helpful for the timely detection of unqualified products and reducing the occurrence of unqualified products. Based on the LightGBM framework， an injection molding product size prediction model was designed based on processing data and parameters. Through feature extraction， abnormal data processing， data set division， model training， model verification， and other steps， a product size prediction model with asymmetric risk characteristics was established. Because of the asymmetric risk of product size exceeding the specification， a weighted correction method was introduced to improve the prediction accuracy of the prediction model for the abnormal size based on the size range in the model training processes. Finally， the Foxconn injection molding size prediction data set was used to verify the prediction model， the results show that the model has higher prediction accuracy for out-of-specification dimensions. The average error of the verification set size prediction results is as 0.015 mm， and the weighted average error considering the asymmetry risk is as 5×10-6 mm. 

Construction and Applications of Machining Process Decision-making Model  for Mould Parts Based on Case Reasoning#br#

XIA Qinxiang, ZENG Weiguo, CHEN Mingxing, XIAO Gangfeng, HUANG Guojun

2022, 33(08):  970-976，985.  DOI: 10.3969/j.issn.1004-132X.2022.08.012

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 Traditional machining processes of mould parts which were relied on manual work had low efficiency and long design cycle， and might not adapt the needs of efficient and intelligent productions of modern mould parts with multi-variety and small batch， and thus a machining process decision-making model was established based on case reasoning. A method of calculating the weight of feature attributes of mould parts was proposed by the rough set theory； the numerical and character local similarities were accurately characterized by adopting the method of normalization and cosine similarity； the similarity threshold of system was dynamically obtained by combining the static and dynamic similarity threshold； based on the process decision-making algorithm combined with K-means clustering and K-nearest neighbor(KNN)， the process files might be generated quickly， accurately， and intelligently. The enterprise production testing results show that using the constructed machining process decision-making model of mould parts， the time for analysis and process route formulation of mould parts may be decreased by 64.5%， the time for machining process preparation of mould parts may be decreased by 40%， the proportion of unreasonable process design may be reduced by 82.8%， and the proportion of missing procedure machining may be reduced by 69.6%， which greatly improve the efficiency of process design and the machining quality of mould parts. 

Analysis for Roll-bending Forming Quality of Spaceflight Thin-walled Cylindrical Workpieces Based on PointCPP-LSF Method#br#

AI Qingbo, ZHANG Jie, CHENG Hui, LYU Youlong, ZUO Liling, HU Lan

2022, 33(08):  977-985.  DOI: 10.3969/j.issn.1004-132X.2022.08.013

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In order to solve the problems that the accuracy and speed requirements of the roll-bending forming quality detection for spaceflight thin-walled cylindrical workpieces might not be met due to the high dependence of the traditional cylindrical fitting method on the initial values of parameters， a PointCPP-LSF method was proposed to realize the analysis of spaceflight thin-walled cylindrical workpiece roll-bending forming quality. Based on point cloud deep learning， a point network for cylindrical parameter prediction (PointCPP) model was established to obtain reliable initial values， and then the cylindrical parameters were iteratively optimized based on the improved LSF method， and combined with the gross error elimination mechanism， the robust curvature radius calculation results were finally obtained. The experimental results show that the proposed method may effectively improve the accuracy and speed of roll-bending forming quality detection for spaceflight thin-walled cylindrical workpieces. 

Effect of Cooling Processes of Hot Dip Galvanizing on C-warped Strip and Its Optimization Technology#br#

QIAN Sheng, Lin Wei, HU Wantong, BAI Zhenhua,

2022, 33(08):  986-992.  DOI: 10.3969/j.issn.1004-132X.2022.08.014

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In order to solve the problems of uneven coating on steel strip surfaces, which was caused by the C-warped strip in a continuous annealing processes of hot-dip galvanizing unit, the influence mechanism of core technology in the cooling processes of C-warped defects was studied. The key process models, such as nozzle cooling model and actual vertical distance distribution model between cooling nozzle and steel strip, were established respectively. The C-warping influence model with warping inhibition rate and warping control sensitivity as quantitative indexes were proposed. And then, a comprehensive optimization method for complete key process parameters of the fan was established, and was realized to cooling control of refined partition of steel strips. At last, the method was applied to the productions of a hot dip galvanizing unit. The results show that the warping degree of the steel strips at the outlet of the unit is effectively reduced.

Autonomous Valet Parking Path Planning for Wire-four-wheel Steering Vehicles

ZHANG Jiaxu, ZHOU Shiying, LI Changlong, GUO Chong, ZHAO Jian

2022, 33(08):  993-1000.  DOI: 10.3969/j.issn.1004-132X.2022.08.015

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Aiming at the autonomous valet parking path planning problems for the wire-four-wheel steering vehicles， an autonomous valet  path planning method with adaptive ability to dynamic obstacles was proposed.  Firstly， the grid map which might describe the environmental information of parking lot was used to transform the autonomous valet parking path planning problem in continuous state space into that in discrete state space， and the isotropic circular structure elements were used to expand the grid map to keep a safe distance between the planned autonomous valet parking path and the obstacles.  Then， the D* Lite algorithm was used to plan the global autonomous valet parking path with adaptive ability to dynamic obstacles， as well the dynamic window method and the arc-line combination method were used to plan the local autonomous valet parking path， which met the kinematic and mechanical constraints of the wire-four-wheel steering vehicles and might guide the vehicles to enter the oblique parking space safely.  Finally， the feasibility of the proposed method was verified by simulation， and the results show that the proposed method may plan a feasible path to guide the vehicles into the target oblique parking space safely in the presence of dynamic obstacles. 

Corrosion Behavior of Aluminum Lithium Alloys in Acidic Environment and Cellular Automata Simulation#br#

GUO Yi, TIAN Gan, LIU Dejun, ZHANG Youhong, CHANG Xinlong

2022, 33(08):  1001-1007.  DOI: 10.3969/j.issn.1004-132X.2022.08.016

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In order to study compatibility of tank materials and liquid propellants, electrochemical tests and full immersion tests were utilized to explore the corrosion mechanism of 2195-T8 aluminum lithium alloys in HNO3, and the corrosion process was simulated based on cellular automata method. The results show that the alloy has the fastest corrosion rate in HNO3 whose mass fraction is as 30%; pitting corrosion occurs in the early stage of corrosion, and then gradually forms exfoliation corrosion. The fitted equivalent circuit reflects the dynamic processes of the alloys in HNO3 and explains the phenomenon of inductive reactance in the fourth quadrant of electrochemical impedance spectroscopy. Cellular automata model adopted Logistic distribution probability as critical condition of corrosion probability, and the simulation results correspond to that of the tests.