Table of Content

25 March 2022, Volume 33 Issue 06

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Review of Management for Mechanical Design and Manufacturing Discipline of NSFC in 2021

2022, 33(06):  631-638. 

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The applications， evaluations and funding of projects for mechanical design and manufacturing discipline（division Ⅱ of engineering science） of the NSFC in 2021， as well as the research progresses and achievements of the executing and finished projects were reviewed. Specific measures of mechanical design and manufacturing discipline were illustrated， such as the reform of scientific fund， academic exchange and discussion， talent cultivation and evaluation of major research programs. Finally， a short prospects of the work in 2022 were introduced. 

External Load Inversion Technology of Machine Structures Based on Multi-information Fusion of Simulation and Measurement

LIU Chunkun, DING Xiaohong, NI Weiyu, LI Guanyun

2022, 33(06):  639-646，655.  DOI: 10.3969/j.issn.1004-132X.2022.06.002

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Aiming at the problems that it was difficult to determine the load boundary conditions of mechanical structures under complex working conditions， an external load inversion technology  was proposed based on multi-information fusion of simulation and measurement. Firstly， the finite element model of the structures to be studied was established， the unit load was applied at the positions of the external load， and the full field strain response of the member was calculated. Then， the optimal layout scheme of measured points and the optimal load coefficient matrix of strain test were obtained based on the D-optimal design principle， and the dynamic response relationship between external load and strain was established. According to the obtained measured point layout scheme， the strain gauges were pasted on the structure to measure the dynamic strain histories of the machine in the actual working processes， the dynamic external load histories of the structure was inversed based on the measured strain histories and the response relationship between load and strain. Taking the working devices of the hydraulic excavator as an example， the hinge point load of the boom was determined by the proposed method， the load inversion results were used as the input of boom transient dynamics analysis， and the simulation values of base measurement points and non-base strain were calculated， the measured values were compared with the simulated values to prove the effectiveness of the proposed method. 

Robot Kinematics Calibration Method Considering Base Frame Errors

NI Huakang, YANG Zeyuan, YANG Yifan, CHEN Xindu, YAN Sijie, DING Han

2022, 33(06):  647-655.  DOI: 10.3969/j.issn.1004-132X.2022.06.003

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A six-axis serial robot error calibration method  was proposed based on the robot geometric parameter errors and the base frame position and attitude errors. Firstly， an geometric parameter error model of the IRB6700 robot was established based on the MD-H method， and the mapping relationship between the geometric parameter errors of the robot connecting rods and the end pose errors of the robot was obtained. Then， the position and attitude errors of the base frame were further considered， and the robot error model  was established considering the errors of the base frame. In addition， to address the cumbersome operation and large accidental errors of traditional calibration methods， an improved parameter identification method was proposed to further improve the operability and calibration accuracy of the calibration processes. Finally， the body calibration experiments and the base frame error disturbance experiments were carried out. The results show that the proposed method decreases the average position error of the robot from 3.1928 mm to 0.1756 mm， and the standard deviation of the position errors decreases from 0.5494 mm to 0.0830 mm. Moreover， the consistency of the parameter identification results under base frame error disturbance is higher than 99%， and the calibration accuracy and stability are improved. 

Flow Field Analysis and Sealing Characteristics Research of Flexible End Face Gas Film Seals#br#

XU Jie, YU Shurong, YAN Ruqi, DING Xuexing, WANG Shipeng, DING Junhua

2022, 33(06):  656-663.  DOI: 10.3969/j.issn.1004-132X.2022.06.004

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A flexible end face gas film seal was proposed for aero-engine shaft end seals. By solving the pressure governing equations under three kinds of sealing end face deformation， the evolution law of the micro-scale flow field characteristics of the sealing gas film was obtained， and the correlation between the key sealing performance parameters and the working conditions was discussed. The research results show that the flexible end face is deformed under the action of the compressed gas film， among which the deformation of the corrugated foil plays a leading role， and the influence of the flat foil is negligible. Compared to the rigid end face， the flexible end face may effectively increase the opening forces of the gas film， and the leakage rate also increases. Under different inlet and outlet pressure ratios， speeds and initial gas film thickness， the sealing characteristics of the two situations show different trends， the gap wedge effectiveness makes the viscous friction torque and gas film stiffness change rate of the flexible end face both are smaller than that of the rigid end face. Inferred from the research results， the flexible end face structure may have a more stable comprehensive sealing performance under high-speed and low-pressure conditions. 

Research on Joint Strength and Radial Knurling Connection Mechanism of Assembled Camshafts

ZHANG Peng, CAO Zeze, KOU Shuqing, WANG Tao, GUO Jibao, LI Jinzhe, WU Lei

2022, 33(06):  664-671.  DOI: 10.3969/j.issn.1004-132X.2022.06.005

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 A finite element predictive approach involving severe plastic deformation of the materials and including three subsequent models（knurling， press-fit and torsion strength） were established  based on the coupled Euler-Lagrangian mesh and Johnson-Cook material model. The sub models were connected in series by transferring the residual stress and strain fields of the shaft tubes to ensure the continuity of the physical fields. The whole process of radial knurling assembly was systematically simulated by connecting each working step model in series； the press-fit force， static torsional strength and the variation characteristics of the cam profiles were predicted and analyzed. The influence law of knurling tool parameters and feed rate on the press-fit force and static torsional strength was revealed. It is shown that numerical results of morphological characteristics of shaft tubes in knurling and assembly area as well as temperature field are in good agreement with the experimental work. The torque strength of the joint is 90% higher than that of a typical passenger vehicle requirement. The torque strength is significantly positive correlated to the press-fit loads. The max displacement of outline of cam is not less than 0.0425 mm. The predicted press-fit and joining strength using the subsequent modeling are validated by the experimental measurement with maximum errors less than 11%. The subsequent models may partly take a place of knurling assembly tests， which is instrumental in shorten development cycles. 

Research on Characteristics of Multi-mode Composite Energy Harvesters Based on Rail Vibration Absorber

QIAN Weiji , YONG Shengjie

2022, 33(06):  672-682.  DOI: 10.3969/j.issn.1004-132X.2022.06.006

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In view of the low efficiency of rail vibration energy harvesters, a composite vibration absorber was designed herein, which made rail vibration absorber coupled with multi-mode piezoelectric-electromagnetic composite energy harvesters. On the premise of effectively reducing the vibration of wheel rail systems, the new device might collect rail vibration energy and power trackside equipment with low energy consumption. A friction coupling vibration model of wheel-rail-composite vibration absorber systems was established. The correctness of the model was verified by comparing with the field measured data. Based on this vibration model, the influences of multi-mode composite energy harvesting modules on vibration characteristics of wheel-rail systems were analyzed. And the power generation performance of the device was studied by using sequential coupling method and parametric analysis method. Analysis results show that the vibration intensity of wheel-rail systems may be reduced effectively by the composite vibration absorber. In the range of 0~600 Hz，the frequency band of vibration energy harvesting may be broaden effectively by the multi-mode piezoelectric-electromagnetic composite energy harvesting modules, and the energy harvesting efficiency is improved. The maximum output power reaches 8.78 mW. The energy harvesting efficiency may be improved by adjusting the structural parameters of energy harvesting modules and improving the strain energy of cantilever beams.

Research on Dynamics Feedforward Compliance Control of 6-DOF Platforms

NI Tao, XU Haiyuan, LI Dong, ZHANG Hongyan

2022, 33(06):  683-689.  DOI: 10.3969/j.issn.1004-132X.2022.06.007

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Compared with the serial robot， the 6-DOF（degree of freedom） platform had the advantages of high stiffness and large load capacity， which was more suitable for the assembly of large workpieces. When the robot was in the docking and assembly states， the end of the robot was subjected to forces and moments from the external environments， and the compliant control of the robot was the basis for completing the tasks. A compliance control method  was proposed based on friction compensation. A dynamics model of the Stewart platform was established. The friction forces of the servo electric cylinder was employed by means of the Coulomb and viscous friction model and the kinematics model including friction torque was derived. A dynamics feedforward compliance control method without using any force sensors at the end of the joints was designed. As the platform is subjected to external force， it will move in the direction of the external force. The experimental results show that the proposed unique methodology achieves an inexpensive and effective yet reliable alternative to be used for compliant control of 6-DOF platforms. 

Discovery of Modular Units for Complex Three-dimension CAD Assembly Model Based on Complex Network

HAN Zhoupeng, LIU Yong, BA Li, SHI Huifan

2022, 33(06):  690-697，755.  DOI: 10.3969/j.issn.1004-132X.2022.06.008

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Three-dimension（3D）assembly model embodied plenty of structure knowledge， which might be employed for design reuse. To acquire the modular knowledge from the existing 3D CAD assembly models in advance for promoting the understanding and reuse of complex 3D assembly model， a method for discovering modular units of complex 3D assembly model  was proposed based on complex network. Firstly， the correlation strength among assembly parts was evaluated comprehensively considering assembly structure， function and material similarity. Secondly， the correlation relationship network for describing correlation of assembly parts in 3D assembly model was constructed based on complex network theory. Subsequently， an improved community detection algorithm for discovering modular units knowledge from complex 3D assembly model was given based on CNM (Clauset-Newman-Moore) algorithm. Finally， 3D CAD assembly of worm reduction box was used for verifying the effectiveness and feasibility of the proposed method. 

Miniature Thread Pairs Automatic Assembly System for Gimbals 

FANG Yuntao, WANG Xiaodong, XU Song, WANG Huibin, LUO Yi,

2022, 33(06):  698-706.  DOI: 10.3969/j.issn.1004-132X.2022.06.009

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An automatic assembly system was developed aiming at solving the problems of weak automation and poor assembly consistency of miniature thread pairs during gimbal assembly. The extraction method of the central positions for the threaded parts and the tightening strategy of multiple miniature thread pairs were studied. Firstly， an improved clarity evaluating function was proposed， and the auto focus of machine vision device was realized based on the evaluating function. Then， aiming at the asymmetry of the end surface features of the threaded shafts and the threaded holes of the inner frame， the variable focused and regional image acquisition method was proposed for extracting the center of the inner and outer threaded parts. Finally， combining the relationship between the input rotation angle and the axial displacement of the inner and outer frames in the loading and unloading processes， the tightening strategy called cross unloading-loading in group was proposed for multiple threaded joints. The system prototype for assembly experiments was built， and the experiments were carried out. The results show that the coaxiality between outer frame and base frame is less than 5 μm， the axial displacements of the inner frame and the outer frame are less than 3 μm， which may meet the coaxiality requirements of the gimbal. 

Rapid Marking Method of Technological Dimension for 3D Part Technological Intelligent Design

LIU Jinfeng, SHENG Sushan, DONG Lei, ZHOU Honggen, LIU Xiaojun, CAO Xuwu, LI Lei,

2022, 33(06):  707-717.  DOI: 10.3969/j.issn.1004-132X.2022.06.010

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 Aiming at the problems that the existing technological dimension marking methods could not accurately describe the feature changes of parts before and after machining， a fast technological dimension marking method oriented to 3D technological intelligent design was proposed. Firstly， a parameterized fast modeling method for the removal body was established， and the organization and management mechanism between the removal feature and the dimension was established. Secondly， in the processes of reverse creation of technological model， the relationship among technological characteristics， removal volume and technological dimension was analyzed， and the constraint mechanism of “feature-dimension-removal volume” was established to quickly generate technological dimension of technological model. Then， the completeness check and standardized processing method of technological dimensions were constructed according to the constraint relationship between the priority of process dimensions marking elements and dimensions. Finally， based on the 3D part technological design system， the technological dimension marking module was integrated and developed. Two typical complex mached parts were selected as the objects to verify the feasibility and effectiveness of the rapid technological dimension marking method. 

Multi-objective Technological Optimization for Medical 316L Porous Structure by SLM

ZENG Shoujin, WU Qirui, WEI Tieping, YE Jianhua, XU Yidan

2022, 33(06):  718-728.  DOI: 10.3969/j.issn.1004-132X.2022.06.011

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In order to solve the poor forming quality of 316L porous structure produced by SLM， the influences of technological parameters on the density， different values of porosity and surface roughness of the formed samples were studied， and a multivariate nonlinear prediction model was established by combining with gray relation analysis. The results show that the fitting degree of the model may reach 96.85%， the optimal technological parameters are 250 W laser power， 800 mm/s scanning speed， 0.08 mm hatching distance， the optimized grey relation grade may reach 0.9195， the density， different values of porosity and surface roughness of the samples are 99.25%， 0.60% and 4.39 μm respectively. There is a positive correlation between the relative density and laser power， and the scanning speed and scanning distance show a trend of first increasing and then decreasing with the density increasing， while the porosity difference value， mean value of surface roughness and laser power， scanning speed， hatching distance maintain a trend of first decreasing and then increasing. Combined with the concept of laser  energy density， the reason of influencing the forming quality by technological parameters is revealed. The melting state of powder is the best when the energy density is 109.65～145.83 J/mm3. 

Research on Present Situation of Quality Control and Performance Optimization of Thermal Spraying Coating Based on Remelting Technology

HAN Bingyuan, , CHU Jiajie, ZHOU Kebing, ZHU Sheng

2022, 33(06):  727-739.  DOI: 10.3969/j.issn.1004-132X.2022.06.012

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The research progresses of various remelting techniques to improve the quality of thermal spraying coatings in recent years were summarized. The following conclusions are obtained:  laser remelting may obviously improve the quality of coatings by eliminating microcracks and unmelted particles in coatings， induction remelting may significantly reduce the porosity of coatings and enhance the mechanics properties of the coatings， and tungsten argon arc remelting can effectively improve the wear and corrosion resistance of coatings and improve the comprehensive properties of coatings. Electron beam remelting and flame remelting also improve the microstructure， microhardness and interfacial bonding strength of the coatings. Finally， the advantages and disadvantages of different remelting technologies were compared， and the development prospects of remelting technology were prospected.

Passenger Car Aerodynamic Noise Optimization Based on Sensitivity Analysis

HE Yansong, TIAN Wei, ZHANG Zhifei , LI Yun

2022, 33(06):  740-746.  DOI: 10.3969/j.issn.1004-132X.2022.06.013

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A computational fluid dynamics model was established to extract the pulsation pressure of the windows by taking the passenger car aerodynamic noise as the research object. The pulsation pressure was applied as excitation to the vehicle acoustic cavity model to simulate the noises at the drivers ears， and the simulation results were in good agreement with the experimental data. The intensity of Curle noise sources on car surface was taken as the optimization objective， and the sensitivity was identified by discrete adjoint method， then the rearview mirror， A-pillar section and hood were selected as the optimization areas. The Hamersley test design method was used to construct the sample space， and the free mesh deformation technique was used to parameterize the sample point model and the corresponding sound power value was calculated. The Kriging interpolation method was used to create the proxy model， and the multi-island genetic algorithm was used for global optimization. The optimization results show that the maximum sound power level of the window surfaces decrease by 2 dB， and the sound pressure level near the drivers ears drops by 0.7 dB（A）. 

Integrated Optimization of Intercell Scheduling and Vehicle Routing

LIAN Yongwei, DONG Zhaorui, LIU Qiong

2022, 33(06):  747-755.  DOI: 10.3969/j.issn.1004-132X.2022.06.014

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In order to improve utilization rates of vehicles， reduce makespan and total costs， an integrated optimization model of intercell scheduling and the vehicle routing was established to minimize makespan and total costs. Interrelationships between processing sequences of parts and transportation routes of exceptional parts were considered. A five-segment coding method including operation， machine， cell， vehicle and vehicle route was proposed. A MOEA/D was designed. To ensure feasible solutions in iterative processes of the algorithm， a binary tree based adjustment method and a vehicle capacity constraint adjustment method were proposed. The proposed model was verified through a case study. Results were compared to those of a common transportation strategy and a vehicle sharing strategy. The proposed integrated optimization model may yield better results on both makespan and total costs.