Table of Content

10 June 2023, Volume 34 Issue 11

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Differential Modification and Topological Structure Design of Complex Tooth Surfaces by Surface Synthesis Method

WEI Bingyang, GU Dewan, CAO Xuemei, YANG Jianjun,

2023, 34(11):  1261-1267，1279.  DOI: 10.3969/j.issn.1004-132X.2023.11.001

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Aiming at the problems that the space surfaces of HRH gears were extremely torsional and it was difficult to correct the curvature, a tooth surface correction method of tool bidirectional trimming point contact was proposed. By using ease-off surface synthesis method, differential modification of tooth surfaces and lean topological structure design, precise control of meshing quality for point contact tooth surfaces was realized. The calculation flow of tooth surface differential lean design for surface synthesis method was established, and three topological structure design forms of light modification, inner diagonal heavy modification and inner diagonal light modification were given. The tooth surfaces meshing stiffnesses, transmission errors and load distribution characteristics of the three forms were compared by LTCA method, and the contact performance of the inner diagonal light modification was the best. The dynamic meshing performance tests of HRH gears were carried out, and ease-off gradient characteristics of point contact tooth surfaces were tested by tooth surface contact spots. The results show that the measured vibration characteristics are consistent with the mesh stiffness and loaded transmission error（LTE） theoretical simulation analysis. The gears run smoothly in a wide range of rotational speed and load, which proves that the tooth shape relation of the designed HRH gears is correct and the differential lean modification is well controlled.

Research on Heat Transfer Enhancement Mechanism of Contact Mechanical Seals with Textured Circumference Surfaces#br#

YU Minfeng, PENG Xudong, MENG Xiangkai, LIANG Yangyang,

2023, 34(11):  1268-1279.  DOI: 10.3969/j.issn.1004-132X.2023.11.002

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Flushing was one of the main measures for heat transfer enhancement of mechanical seals. But in some special occasions, the flow rate of flushing was given, so some forced heat transfer measures were needed to improve the operating environment of mechanical seals. Through processing texture on the circumference surfaces of the sealing rings and aiming at the condition of a given amount of flushing, the influences of speed and depth to diameter ratio on interface temperature, local Nu on circumference surfaces and flow field in textured regions were analyzed by SST k-ω turbulence model and Ω method, heat transfer mechanism of texture processed on rotor or stator was compared and analyzed. The results show that under the same working conditions, flow rate of flushing and texture geometric parameters, the heat transfer of rotor is better if the texture is set on the circumference surfaces of rotor and stator separately. Under the same speed, when texture is processed on the circumference surface of rotor, reduction of the aspect ratio may increase the areas with poor heat transfer inside the texture and weakened heat transfer. But when texture is processed on the circumference surfaces of stator, the conclusion is completely opposite. As the speed increases, a new area of poor heat transfer appears in a small aspect ratio rotor texture, the heat transfer intensity per unit area is decreased significantly. Therefore, in order to obtain better heat transfer effectiveness, the small aspect ratio texture may be selected under low speed, and the large aspect ratio texture may be selected under high speed.

Study on Grinding Force Model of Longitudinal Ultrasonic Assisted Helical Grinding Ti3Al Microholes

GAO Guofu, WANG Deyu, PAN Xianrong, QIAO Huai, FU Zongxia, XIANG Daohui, ZHAO Bo

2023, 34(11):  1280-1286.  DOI: 10.3969/j.issn.1004-132X.2023.11.003

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In order to establish the prediction model of grinding force in ultrasonic assisted helical grinding processes and give full play to the guiding role of grinding force in the optimization of Ti3Al microhole grinding parameters, the changes of cutting deformation forces and friction forces were analyzed under ultrasonic vibrations based on the chip section area theory, and the grinding force model of ultrasonic helical grinding hole was established. The grinding force data were collected and verified with the established model by setting up an ultrasonic assisted helical grinding Ti3Al microhole experimental platform. The results show that the grinding forces decrease with the increasing of spindle rotation speeds and increase with the increasing of feed speeds. When the ultrasonic amplitudes increase from 0 to 1.6 μm, the surface grinding forces and axial grinding forces are decreased by 27.2% and 28%, respectively. The prediction results of ultrasonic helical grinding force model are in good agreement with the experimental data, and the numerical errors are kept within 20%, which provides a theoretical basis for the optimization of processing parameters of ultrasonic assisted helical grinding of Ti3Al microholes.

Influences of Magnetic-Gas Load Ratio on Supporting Characteristics and Rotor Dynamics Characteristics of Foil-Magnetic Hybrid Bearings

LEI Xinpei, FENG Libo, ZHANG Hang, FENG Kai

2023, 34(11):  1287-1295,1305.  DOI: 10.3969/j.issn.1004-132X.2023.11.004

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 Foil-magnetic hybrid bearing was a new type of high-performance active control bearing that might reduce the friction loss of foil bearing before take-off, and might improve the load-bearing and dynamics performance of magnetic bearings at high speeds. A design method of foil-magnetic hybrid bearings was proposed, and an experimental bench for supporting characteristics of foil-magnetic hybrid bearings and a rotor experimental bench for foil-magnetic hybrid bearings were designed and built. The influences of the magnetic-gas load ratio (which was the load distribution ratio between the gas foil bearings and the active magnetic bearings) on the supporting characteristics and rotor dynamics characteristics of foil-magnetic hybrid bearings were investigated through experiments. The experimental results show that the overall static stiffness and stiffness change rate of the foil-magnetic hybrid bearings are improved compared with the foil bearings. The structural stiffness of the foil-magnetic hybrid bearings increases with the increasing of frequency, and the equivalent viscous damping shows a trend of first decreasing and then increasing with the increasing of frequency. In addition, a suitable load ratio may reduce the take-off speed, improve friction loss, suppress sub-frequency vibrations, and help to improve the high-speed stability of the rotors.

Parameter Identification of Nonlinear Hydro-pneumatic Suspensions Based on Feature Extraction in Time-frequency Domain

WU Jianwei, SUN Beibei, JIANG Qiubo, CHEN Lin

2023, 34(11):  1296-1305.  DOI: 10.3969/j.issn.1004-132X.2023.11.005

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 Considering the limitation of the nonlinear parameter identification method based entirely on the time domain or the frequency domain， a parameter identification method for nonlinear hydro-pneumatic suspensions was proposed based on feature extraction in time-frequency domain. The vehicle dynamics simulation models with nonlinear hydro-dynamic suspensions were established， the IFFT method was used to obtain the road excitation with the level of the standard road surface， the feature quantities in the time-frequency domain of the experimental results were extracted by combining with the wavelet analysis and filtering， and an optimization model for identification of nonlinear hydro-pneumatic suspension parameters was constructed. By minimizing the feature quantities of simulation and experimental results in the time-frequency domain， the nonlinear parameters of the hydro-pneumatic suspensions were accurately identified under actual conditions. The quantitative and qualitative analyses of the identification show that the identification results are accurate and reliable. By combining road time domain modeling， wavelet filtering technology and construction method for the optimization model with simulated annealing algorithm， an effective and reliable identification method was provided for parameter identification of nonlinear suspension systems. 

Research on Characteristics of Flow Fields during LHP Processes

FU Yuantao, WEN Donghui, KONG Fanzhi, GAN Zuokun, CHENG Zhichao,

2023, 34(11):  1306-1314.  DOI: 10.3969/j.issn.1004-132X.2023.11.006

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The action form of fluid flow on workpiece surfaces in LHP was analyzed, the mathematic models of viscous shear stress and hydrodynamic pressure were derived. The flow field of LHP was numerically simulated and the influences of the sizes of polishing roller and polishing parameters on the numerical values and distribution uniformities of hydrodynamic pressure and viscous shear stress were analyzed. The results show that the values of hydrodynamic pressure and viscous shear stress increase with the increasing of roller diameters and rotation speeds, while the distribution uniformity decreases. The smaller the values of polishing clearance, the larger the values of hydrodynamic pressure and viscous shear stress, and the better the distribution uniformity. Finally, taking K9 glass as the experimental object, the formation processes of surface morphology and surface roughness were investigated by using a self-made LHP experimental platform.

RGCMvMRDE and Its Applications in Rolling Bearing Fault Diagnosis

ZHENG Jinde, CHEN Yan, TONG Jinyu, PAN Haiyang

2023, 34(11):  1315-1325.  DOI: 10.3969/j.issn.1004-132X.2023.11.007

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Multi-scale reverse dispersion entropy(MRDE） might effectively measure the complexity of time series, but MRDE had defects in coarse-grained structure and lacked the effective use of other channel information in characterizing the nonlinear fault characteristics of rolling bearings. To accurately extract fault features from bearing signals, combined with the ideas of refinement and generalized composite multi-scale, the multi-variate sample entropy theory that characterized the multi-variate complexity of synchronized multi-channel data was applied to the rolling bearing fault diagnosis and RGCMvMRDE was proposed. Then, a rolling bearing fault diagnosis method was proposed based on RGCMvMRDE and gravitational search algorithm support vector machine(GSA-SVM). Firstly, the RGCMvMRDE was applied to comprehensively characterize the fault feature information of rolling bearings and the fault feature sets were contracted. Secondly, GSA-SVM was used to identify the fault type intelligently. Finally, the proposed fault diagnosis method was applied to analyze experimental data of rolling bearing with comparing with the existing fault feature extraction methods based on MRDE, generalized MRDE(GMRDE） and refined composite multi-yariate multi-scale permutation entropy RCMvMPE. The results indicate that the proposed method may effectively and accurately identify different fault types and fault degrees of rolling bearings and the diagnosis effectiveness is better than those of the compared methods.

Health Assessment Method of Shield Machine Cutterheads Driven by Association Rule Mining

LIU Yao, CHEN Gaige, LIU Zhenguo, KONG Xianguang, CHANG Jiantao

2023, 34(11):  1326-1334,1342.  DOI: 10.3969/j.issn.1004-132X.2023.11.008

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Traditional mechanism modeling method had large errors with the actual construction environment, whereas data-driven modeling mostly used black-box models, which was not conducive to knowledge discovery and understanding, therefore a knowledge mining-based shield machine cutterhead health assessment method was proposed. For the characteristics of shield excavation data with many dimensions, massive heterogeneity and strong noise interference, specific data pre-processing, feature screening and continuous feature discretization methods were proposed to establish a knowledge mining dataset combining the domain knowledge of shield excavation and machine learning algorithms. Then, the association rule mining algorithm was used to extract the mapping relationship among key features and different cutterhead health levels. The original rules were evaluated and ranked by using a comprehensive evaluation index that integrated reliability, completeness and simplicity to finally realize the shield machine cutterhead health assessment. The proposed method was validated based on the actual engineering data of one tunneling section of Xiamen Metro Line 3. The results show that the mined knowledge rules have a good agreement with the actual data distribution (average 93% or more), which verifies the effectiveness of the method.

Adaptive Nonlinear Sliding Mode Contour Control of Two-axis Direct Drive Servo Feed Systems Based on Friction Compensation

JIN Hongyan, WANG Lei, ZHAO Ximei

2023, 34(11):  1335-1342.  DOI: 10.3969/j.issn.1004-132X.2023.11.009

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In order to meet the requirements of high precision for two-axis direct drive servo feed systems, based on friction compensation, an adaptive nonlinear sliding mode contour control(ANSMCC) method was proposed to take into account the requirements of machining precision and response speed. An equivalent contour error model suitable for large curvature contour machining was established, and considering the influences of uncertain dynamics in the system, an improved LuGre nonlinear friction dynamic model with accurate and real-time compensation was established. In order to improve the contour performance of the two-axis direct drive servo feed systems, an ANSMCC method was designed based on the nonlinear sliding mode surface, where the nonlinear sliding mode surface contained the contour error components. By changing the values of the gain matrix in the nonlinear sliding mode surface, the damping ratio of the system might be changed in real time, so as to coordinate the relationship between the contour errors and the system response speeds. The experimental results show that the proposed method may overcome the dynamic influences of uncertainty in the operation of system, accurately track the large curvature contour curves, improve the contour machining accuracy.

Study on Infrared Heat Source-assisted Open-space Industrial Robotic FDM Equipment Design and Forming Performance

YANG Fei, JIANG Wei, CHEN Cheng, HUANG Zhigao, ZHOU Huamin,

2023, 34(11):  1343-1352,1385.  DOI: 10.3969/j.issn.1004-132X.2023.11.010

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To solve the key problems of FDM for open-space industrial robots, the FDM equipment and control system were developed based on a 6-axis articulated robot. The printing head with assisted heating was designed, and the printing control system and robot control system were developed. By proposing the synchronous matching method of printing head extrusion speed and robot motion, the stable operation of the robotic FDM equipment was realized. Then the infrared heat source-assisted industrial robotic FDM forming method was proposed, and the influence law of the auxiliary heat source parameters on the macroscopic mechanics properties and surface roughness of the fabricated parts were studied through processing tests, and the enhancement mechanism was analyzed through microstructure characterization. The results show that under the open-space environment, the infrared heat source may effectively increase the substrate temperature, significantly enhance the diffusion entanglement of molecular chains at the strand interface and improve the interfacial bonding strength, resulting in a 17.6% increase in the interlayer bonding strength and a 58% reduction in the surface roughness of the parts, which verifies the feasibility and high efficiency of the infrared heat source-assisted open-space industrial robotic FDM method.

Electric-field-driven Jet Deposition Micro 3D Printing of High Resolution Aluminum Nitride Ceramic-based Circuits

YU Zhihao, ZHANG Guangming, LI Hongke, DUAN Peikai, YU Zun, TAI Yuping, LI Wenhai, XU Quan, ZHAO Jiawei, LAN Hongbo

2023, 34(11):  1353-1363.  DOI: 10.3969/j.issn.1004-132X.2023.11.011

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At present, the existing technology still faced great challenges in the mass manufacturing of high resolution and high density circuits at low-cost, which might not meet the requirements of high frequency, high speed and high density integration of ceramic-based circuits. Therefore, a new method was proposed for electric-field-driven jet deposition micro 3D printing of high resolution aluminum nitride ceramic-based circuits in combination with sacrificial coatings. The sacrificial coating was used to overcome the instability of the jet flows caused by the roughnesses of the ceramic surfaces, and the line widths were further reduced by the hydrophobic characteristics of the sacrificial coating, and the fabrication of high-resolution circuits was realized. The effects of printing parameters(voltage, air pressure, printing height, printing speed), sacrifice layer and sintering process on the width and morphology of the printed silver wire were studied by experiments and the processing parameters were optimized. Finally, using a conductive silver paste with 70%(mass fraction) silver content combined with optimized processing parameters, a variety of complex circuit patterns were fabricated on the surface of aluminum nitride substrates, including a high-density, high-resolution circuit pattern with a line width/line spacing of 2/3 and a conductive silver line with a minimum line width of 8.1 μm reported so far. The results show that the new method of electric-field-driven jet deposition microscale 3D printing of aluminum nitride ceramic-based circuits in combination with sacrificial coatings may provide an effective way for the low-cost mass manufacturing of miniaturized and high-power ceramic-based integrated circuits.

Study on Pressure Response Characteristics of New Pneumatic Position Sensor under Irradiation Environments

XIANG Routong, WANG Shilong, ZHOU Jie, YI Lili

2023, 34(11):  1364-1371.  DOI: 10.3969/j.issn.1004-132X.2023.11.012

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The electronic components were involved in the sensitive elements and conversion elements of the general pneumatic position sensors, which might not be applied to the irradiation environments. Aiming at the application problems of position sensors under irradiation environments, a scheme of new pneumatic position sensor was proposed to judge whether the measured part reached the preset position by detecting the numerical changes of the flow field in the corresponding position. The scheme had the problem of lagging pressure response, which led to the lagging phenomenon of the position feedback of the tested parts, so it was crucial to accurately estimate the position compensation of the sensors and improve the detection precision on the positions. The internal flow of the pneumatic position sensors was analyzed and the prediction model of the pressure response was established. By orthogonal tests, the sensitivity of each engineering variables to the coefficients in prediction model and response time was revealed and the coefficients were further fitted by simulation. The results show that the prediction model may meet the requirements of the lagging position when the maximum error of response time is within 0.01 s and the repeated positioning errors of the prediction model are less than 1 mm when the maximum velocity is as 100 mm/s.

Transmission Model and Path Planning of Variable-size Materials in Continuous Alternate Wheel Systems

TANG Wei, SUN Yu, GU Jinfeng, CHEN Yuan

2023, 34(11):  1372-1385.  DOI: 10.3969/j.issn.1004-132X.2023.11.013

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 Most of the traditional logistics equipment had problems such as single transmission mode and difficulty in flexible adjustment of transmission lines. For the modular material transmission platform with honeycomb layout, based on the three-wheel model and Newton-Euler dynamics, general kinematics and dynamics models for the variable-size material transfer were respectively derived on the basis of the omni-directional wheel systems to ensure the accuracy and smoothness of the transfer. An IACSPF algorithm generated by fusion was used for material transmission path planning, which improved the convergence speed of the algorithm and avoided falling into local optimization. Finally, simulations and experiments were carried out to verify the transmission trajectory, speed and path planning of the different size materials. The results show that the variable-size materials may be stably transported to the vicinity of the target by the optimal path. The relative errors of trajectory and speed average are less than 4.27% and 8.33% respectively. The optimization rates of the length, time and number of turning points of the planned path are 20.77%, 55.39% and 73.33% respectively, and the safety distance is larger, which verifies the rationality of the proposed general transmission model and the effectiveness of the IACSPF algorithm.