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    Development Status and Prospect of Key Rail Grinding Equipment and Technology of Grinding Stone
    ZHANG Wulin, FANXiaoqiang, ZHU Minhao, DUAN Haitao
    China Mechanical Engineering    2022, 33 (19): 2269-2287.   DOI: 10.3969/j.issn.1004-132X.2022.19.001
    Abstract255)      PDF (17216KB)(499)       Save
     The rail grinding strategies and techniques were reviewed, and the key equipment of the grinding methods using grinding wheels(active grinding and high-speed passive grinding)and the milling and grinding compound process were summarized. Meanwhile, the research status of rail grinding stone(grinding wheel, equipped with rail grinding train and used for cutting tools)were reviewed from ingredients, forming processes, structural design and grinding performance evaluation criterions, etc. It was concluded that the fine formula design, scientific evaluation criterions, etc. were the main challenges for the development of high-performance grinding stones. Finally, it was pointed out that the greenization, standardization, and intelligence were the important directions for future development of grinding stone technology. 
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    Online Monitoring Method for NC Milling Tool Wear by Digital Twin-drivenLI Congbo
    SUN Xin, HOU Xiaobo, ZHAO Xikun, WU Shaoqing
    China Mechanical Engineering    2022, 33 (01): 78-87.   DOI: 10.3969/j.issn.1004-132X.2022.01.009
    Abstract246)      PDF (11516KB)(392)       Save
    In order to solve the problems of large errors of tool wear prediction model caused by continuous aging of CNC milling machines and difficulties of on-line acquisition of dynamic data during machining, a digital twin-driven online tool wear monitoring method was proposed. Firstly, a neural network was used to extract features from multi-source data in the machining processes, and a quantitative model of tool wear time varying deviation was established considering machine aging. Based on this, an on-line prediction method of tool wear in CNC milling was proposed. Then, a numerical control milling digital twin system for tool wear was developed to online sense the dynamic data and simulate the tool wear processes in real time. Finally, this method was applied to actual machining and compared with other prediction methods. The results show that this method may reduce the prediction errors and realize the accurate prediction of tool wear value.
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    Development of Gear Measurement Technology during Last 20 Years
    SHI Zhaoyao, YU Bo, SONG Huixu, WANG Xiaoyi
    China Mechanical Engineering    2022, 33 (09): 1009-1024.   DOI: 10.3969/j.issn.1004-132X.2022.09.001
    Abstract231)      PDF (72652KB)(362)       Save
    There were two forces that promoted the development of gear measurement technology. One was the continuous new requirements for gear measurement put forward by industrial development, and the other was the penetration of continuously improving related technologies in the field of gear measurement. Since the 21st century, the convergence of these two forces promoted the rapid development of gear measurement technology. Based on a brief review of the evolution of gear accuracy theory and gear measurement technology in the 20th century, the basic framework of gear generalized accuracy theory was put forward. The gear measurement technology during the last 20 years was systematically summarized from the aspects of gear full-information measurement technology, in-site rapid gear sorting and detection technology, extreme measurement technology for extra-large gears and micro gears, high-precision gear artifacts and traceability, etc. There is more than 100 years since the beginning of gear precision measurement, and it is currently in the critical stage of the transition from the 3rd generation to the next-generation of gear measurement. The overall technical concept of next-generation of gear measurement was presented, the basic theory and key technical problems that must be overcome were listed for realizing the next-generation of gear measurement, and the research focus and scientific issues of gear measurement in the next 10 years were prospected.
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    Electromechanical Coupling Modeling and Dynamic Characteristic Analysis of Wind Power Transmission Systems under Operation Conditions
    QIN Datong, LYU Xuehui, CHEN Ruibo, YANG Zhanbin
    China Mechanical Engineering    2022, 33 (03): 253-260.   DOI: 10.3969/j.issn.1004-132X.2022.03.001
    Abstract216)      PDF (5566KB)(227)       Save
    To reveal the electromechanical coupling dynamic characteristics of the wind power transmission systems under the variable speeds and variable load operation conditions, the electromechanical coupling model of the wind power transmission systems including the gear system dynamics model, the finite element model of permanent magnet synchronous generator and the operation control model of wind turbine was established, taking into consideration of the nonlinear factors such as gears time-varying meshing stiffness, cogging effect and magnetic saturation of generators. The dynamic responses of the systems under the starting and power generation operation conditions and the electromechanical coupling dynamic characteristics of the system were analyzed. The results show that the dynamic responses of the wind power transmission systems are stable under the starting condition; under the power generation operation condition, the wind power transmission systems are under a variable speed and variable load state, and low-frequency torsional vibrations are vulnerable to be excited and dynamic responses are complicated. Under the effects of generator cogging, magnetic saturation and other factors, the currents and electromagnetic torques may produce main harmonic frequency fluctuations caused by time harmonics and space harmonics. Because of the electromechanical coupling effects, the gear vibration characteristics and the electromagnetic characteristics may affect each other. The currents and electromagnetic torques contain more mechanical vibration frequency components related to gear meshing. At the same time, the electromagnetic torques react to the gear systems, which excites rich structural frequency components of the gear systems. 
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    State-of-the-art on MQL Synergistic Technologies and Their Applications
    YANG Jianzhang, WANG Chengyong, YUAN Yaohui, YUAN Songmei, WANG Xibin, LIANG Cile, LI Weiqiu
    China Mechanical Engineering    2022, 33 (05): 506-528.   DOI: 10.3969/j.issn.1004-132X.2022.05.001
    Abstract205)      PDF (22261KB)(326)       Save
    MQL technology had the advantages of low cutting fluid consumption and high lubrication efficiency. However, there were more problems such as inadequate lubrication and low cooling performance under the specific conditions. MQL synergistic technology, such as cryogenic air or liquid carbon dioxide et.al. which combines the advantages of cooling and lubrication, might effectively solve the machining problems of difficult-to-cut materials. The latest research of principle, key devices and technology applications of various types of MQL synergistic technology were summarized. The performance of various devices and their parameter regulation characteristics were analyzed in details. Combining with the applications and the mechanism of MQL synergistic technology, the machinability in titanium alloy, nickel alloy, stainless steel and other difficult-to-cutting materials were analyzed. In addition, a sustainable analysis of various types of MQL synergistic technology was provided. The purpose is to provide technical support and reference for the engineering applications of clean cutting technologies.
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    Research on Virtual Grinding Wheel  Modeling Based on Convex Polyhedron Collision Detection
    CHEN Hao, ZHAO Ji, XU Xiuling, YU Tianbiao
    China Mechanical Engineering    2022, 33 (02): 127-133.   DOI: 10.3969/j.issn.1004-132X.2022.02.001
    Abstract203)      PDF (9130KB)(216)       Save
     The bounding sphere was usually used to detect the collision of grinding grains in the virtual grinding wheel modeling methods. When the bounding spheres were in contact, there was still a large gap between the abrasive grains, which resulted in a big difference between the virtual and actual grinding wheel surfaces. To solve this problem, a virtual grinding wheel modeling method was proposed based on convex polyhedron collision detection. The mathematical model of the random positions of abrasive grains on the grinding wheel surface was derived in detail. The interferences of grains were judged based on the convex polyhedron collision detection method, and the virtual grinding wheel was finally generated. The virtual grinding wheel surfaces generated by convex polyhedron and bounding sphere collision detections were compared. The improved method may generate virtual grinding wheel with 60% volume fraction of abrasive grains, while the original method may not generate virtual grinding wheel with more than 50% volume fraction of abrasive grains. The results indicate that the improved method may generate a virtual grinding wheel with a higher abrasive volume fraction and more randomness surface. Finally, the virtual grinding wheel surfaces were compared with the actual grinding wheel surfaces, and results show that the virtual grinding wheel surface has the characteristics of actual grinding wheel surface. 
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    Research on Traveling Wave Resonance Characteristics of Spiral Bevel Gears and Its Influence Laws under Parameter Adjustment
    LUAN Xiaochi, ZHAO Yu, SHA Yundong, LIU Gongmin, ZHAO Qian,
    China Mechanical Engineering    2021, 32 (24): 2899-2908,2914.   DOI: 10.3969/j.issn.1004-132X.2021.24.001
    Abstract191)      PDF (7272KB)(116)       Save
    Aiming at the driven bevel gear fracture failure of a certain type of aero-engine central drive bevel gear due to traveling wave resonance in actual processes, combination of simulation analysis and test verification was used to study the traveling wave resonance characteristics and influence laws of spiral bevel gears under parameter adjustment. The modal analysis of the driven gears was carried out based on finite element method, and the relationship between the thickness of the spoke plate and the working temperature with the gear traveling wave resonance characteristics was discussed. Transient dynamic analysis of meshing gears was carried out based on Hertz contact theory, and the influences of load power, operating temperature and damping factor on the stress distribution of driven bevel gears under traveling wave resonance were discussed. The comparison of simulation and test results shows that the errors of simulation results of modal calculation and dynamic analysis are within a reasonable range. Under the premise of meeting the relevant requirements of gear design, the resonance speed or resonance frequency may be avoided by adjusting the thickness of the spoke plate. In terms of the sensitivity of the resonance parameters of the vibration stress distribution, the analysis shows that when the gear is working in the third or fourth nodal diameter traveling wave resonance states, the stress values at the tooth roots are the largest, and the stress values on the front surfaces of the spoke plate are the smallest; when the temperature and damping factor changing, the change of stress values at front of the driven bevel gear spoke plate is small, and the change of stress values at the back of the spoke plate and tooth root is big. Therefore, in improvement and optimization designs of the gears, it is necessary to deal with the third or fourth nodal diameter traveling wave resonance.
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    Hydrodynamic Force Calculation Method of Tracked Equipment Based on Artificial Lateral Line#br#
    WU Jiaxiong, SHEN Yanhua , YANG Shudi, FENG Zhipeng
    China Mechanical Engineering    2022, 33 (10): 1135-1141.   DOI: 10.3969/j.issn.1004-132X.2022.10.001
    Abstract191)      PDF (7590KB)(290)       Save
     Aiming at the challenge that the hydrodynamic forces of underwater equipment could not be measured in real time, a method for calculating the hydrodynamic forces of track equipment was proposed based on ALL. Through the ALL system of the track equipment, the pressure values of different incoming flow speeds and angles were extracted, and the distribution law of pressure values was used to perceive the local flow field information of the track equipment. Through the hydrodynamic force restraint experiments of the track equipment combined with the computational fluid dynamics(CFD)simulation method, the functional relationship between the front surface shapes of the track equipment and the viscous coefficient was established. Based on the flow field perception results of the ALL, the hydrodynamic force empirical model of the track equipment was derived. The verification results show that the pressure distribution characteristics of the ALL may effectively identify the incoming flow velocity and angle. The hydrodynamic force empirical model combined with the results of ALL perception may be used to estimate the hydrodynamic force of underwater track equipment in real time, the water resistance calculation error of underwater track equipment model is within the acceptable range of the engineering application. 
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    Body Design of a Storage Tank Wall-climbing Robot Based on Magnetic Adsorption
    QIU Shicheng, WU Jianbo, ZHAO Hengzhong, WANG Shen, HU Qifan, YAN Rong
    China Mechanical Engineering    2022, 33 (03): 270-278.   DOI: 10.3969/j.issn.1004-132X.2022.03.003
    Abstract187)      PDF (11924KB)(210)       Save
     For the automatic detection of weld defects in large storage tanks, a wall-climbing robot needed to complete automatic omni-directional scanning. Firstly, according to the force state of the wall-climbing robot under different operating conditions, a mechanics model of the wall-climbing robot was established to analyze and obtain the four unstable hazards of non-sliding, non-longitudinal rollover, non-lateral rollover and compound motion state. The force state of the permanent magnet adsorption wheel was simulated and optimized by Maxwell software to meet the adsorption requirements. At the same time, the coding wheel with auxiliary adsorption function was designed to supplement the margin of safe adsorption force while feeding back the position information to increase the obstacle crossing and anti-instability abilities. Finally, according to the design model, the wall-climbing robot body was manufactured and tested. The test results prove that the robot designed herein may realize the omnidirectional driving operations with load stability at various ustable hazards.
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    Progresses of Surface Engineering in Extreme Environments and Its Common Scientific Problems
    CHANG Keke, CHEN Leilei, ZHOU Ruonan, XIAO Xuelian, WANG Fangming, WANG Liping
    China Mechanical Engineering    2022, 33 (12): 1388-1417.   DOI: 10.3969/j.issn.1004-132X.2022.12.001
    Abstract177)      PDF (51339KB)(276)       Save
    The strong coupling effects from multi factors in the typical extreme environments of “three depths and one pole” (deep space, deep sea, deep earth and polar) led to the coexistence of multimode damages and failures, such as material corrosion, wear, fatigue, and fracture, which bringed severe challenges to the high precision, high reliability, and ultralong service life of mechanical systems. Surface engineering technology was one of the most effective ways of surface strengthening and life extension. The researches of relevant methods and basic scientific problems were important supports for structural optimization and material designs of highsafety and highreliability mechanical engineering equipment in extreme environments. The general methods of surface engineering technology and their applications in the fields related to extreme environments were introduced, the common basic scientific problems of surface engineering in extreme environments were analysed, focused on the implements of theoretical calculation methods in solving problems, and the development directions of surface engineering in extreme environments were commented.
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    China Mechanical Engineering    2022, 33 (12): 1-.  
    Abstract176)      PDF (181211KB)(483)       Save
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    Design and Performance Verification of Marine Intelligent Water-lubricated Stern Bearings with Temperature Sensing
    XUE Enchi, GUO Zhiwei, YUAN Chengqing,
    China Mechanical Engineering    2022, 33 (14): 1639-1645.   DOI: 10.3969/j.issn.1004-132X.2022.14.001
    Abstract176)      PDF (3728KB)(121)       Save
    An innovative design of marine intelligent water-lubricated stern bearings was proposed to assist the tail shaft system for improving operating state monitoring and performance prediction in harsh environments. Based on the micro embedded self-powered monitoring systems and the water-lubricated bearing structures and material designs, some critical performance parameters of water-lubricated bearings in ship sailing were measured and analyzed in real-time, which were used for operating state identification, evaluation, and life prediction. As an example, the internal temperature of bearings was chosen for feasibility verification of the above intelligent water-lubricated tail bearings by CBZ-1 friction and wear tester. The results show that the internal temperature of the bearings may effectively reflect their lubrication and working conditions. Under water lubrication conditions, the initial period heating rate is as 0.1~0.4 ℃/min, the final period heating rate is as 0~0.01 ℃/min, and the temperature during the steady operations is as 29~33 ℃. Under dry friction conditions, the three data are 0.6~1.4 ℃/min, 0.03~0.25 ℃/min and 36~45 ℃, respectively. The huge temperature differences in different lubrication states make it possible to determine the bearing lubrication conditions, which means that temperature monitoring will greatly improve the reliability of water-lubricated bearings.
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    Large-field and High-precision Dynamic Positioning Method of Indoor Mobile Robots
    TIAN Mingrui, , YANG Hao, HU Yongbiao
    China Mechanical Engineering    2022, 33 (02): 194-201.   DOI: 10.3969/j.issn.1004-132X.2022.02.009
    Abstract166)      PDF (5717KB)(129)       Save
    High-precision indoor positioning process was the basis and prerequisite for mobile robots to fulfill tasks such as autonomous navigation, motion control, and cooperative operation. a large-field and absolute positioning method was proposed for indoor mobile robots based on the principle of monocular vision positioning. This method was suitable for the synchronous dynamic positioning of indoor multi-mobile robots, the problems of multi-camera nonlinear calibration and field fusion in the large-field environment were solved, and the camera calibration accuracy was improved by 52.6%. A high-speed positioning algorithm was designed based on optical beacons to improve the dynamic positioning accuracy of the mobile robots, where the image processing speed of the positioning system was improved. Then the dynamic errors of the positioning system were predicted and compensated. The experimental verification of each algorithm shows that the proposed method may perform high-precision dynamic positioning of multiple indoor high-speed mobile robots. When the robot moving speed is less than 3.2 m/s, the average dynamic positioning errors of the system position are less than 5 cm, and the average dynamic positioning errors of the system attitude angle are less than 0.6°.
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    Research Progresses of Micro-area Induction Heating Technology in Micro/Nano Systems
    WU Dezhi, CHEN Zhuo, HAI Zhenyin, CHEN Liang, YE Kun, WANG Lingyun, ZHAO Libo
    China Mechanical Engineering    2022, 33 (01): 2-14,23.   DOI: 10.3969/j.issn.1004-132X.2022.01.001
    Abstract165)      PDF (9420KB)(115)       Save
    Micro-area induction heating(MIH), as a localized heating technique with characteristics of non-contact, controllable, and fast thermal-response, was shown numerous potentials in microsystems, such as microelectromechanical systems and microfluidic chips. The fundamentals of MIH were introduced herein, and the research progresses of MIH in the fields of packaging, driving, material growth, et al, was presented systematically. Furthermore, some existing technique problems needed to be solved were analyzed, and several prospective research directions of MIH were pointed out.
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    Navigation Trajectory Prediction Method of Inland Ships Based on Multi-model Fusion
    ZHANG Yang, GAO Shu, HE Wei, CAI Jing
    China Mechanical Engineering    2022, 33 (10): 1142-1152.   DOI: 10.3969/j.issn.1004-132X.2022.10.002
    Abstract165)      PDF (2807KB)(83)       Save
     Inland waterway navigation was an important part of the modern comprehensive transportation systems. The real-time and high-precision ship trajectory prediction method was helpful to effectively avoid water traffic accidents and enhance the ability of automation and intelligent supervision. Aiming at the problems that the accuracy of the existing inland ship trajectory prediction was not high, in order to improve the short-term prediction accuracy of ship trajectory, comprehensively using the recent AIS (automatic identification system) data and historical AIS data of the ships, and based on the relationship among trajectory and speed, course, and the characteristics of inland waterway, the temporal convolutional network model for speed and course prediction, ship trajectory dynamics equation model and adaptive double-hidden layer RBF network were constructed. The ship trajectory prediction method based on multi-model fusion was proposed. Experimental results show that the proposed method has obvious improvement in trajectory prediction accuracy and may meet the real-time requirements. 
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    State-of-the-art of Key Maritime Rescue and Salvage Equipment and Technology
    ZHAO Jiechao, JIN Hao, CHEN Jian, PAN Changcheng, ZHANG Yingxiang, WANG Jiwu, WENG Datao
    China Mechanical Engineering    2022, 33 (04): 432-451,458.   DOI: 10.3969/j.issn.1004-132X.2022.04.007
    Abstract164)      PDF (3281KB)(123)       Save
     To promote the modernization of the national emergency management systems and capabilities, combined with the current development of maritime emergency rescue capabilities in China, the key issues exposed in some typical maritime emergency rescue cases in recent years were deeply analyzed, and the conclusion that “systematic construction” was the core issue that urgently needed to be strengthened in the construction of Chinese maritime rescue and salvage equipment and technology was pointed out. From the perspective of the land-sea-air-space integrated, aiming at the four major Chinese rescue and salvage missions of life rescue, environmental rescue, property rescue, and emergency rescue and salvage, this paper systematically divided the key equipment technology of maritime rescue and salvage into 7 types according to the dimensions of space-based, air-based, water surface, and underwater. Aiming at the current development of each type of key equipment technology, the Delphi method, brainstorming method and bibliometric method were used to carry out research and judgment on the development of key maritime rescue and salvage equipment and technology. The results of the study selected 13 key equipment technologies that require urgent attention from the 7 categories of key equipment technologies. Meanwhile, the current challenges faced by each key equipment technology were systematically analyzed, and recommendations for the development goals and core construction tasks in the next 5~15 years were given as well. 
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    External Load Inversion Technology of Machine Structures Based on Multi-information Fusion of Simulation and Measurement
    LIU Chunkun, DING Xiaohong, NI Weiyu, LI Guanyun
    China Mechanical Engineering    2022, 33 (06): 639-646,655.   DOI: 10.3969/j.issn.1004-132X.2022.06.002
    Abstract164)      PDF (7689KB)(146)       Save
    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. 
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    Chip Formation and Tool Wear in High-speed Cutting of Hardened Steels under Cryogenic Liquid Nitrogen Cooling
    WU Shixiong, ZHANG Wenfeng, LIU Guangdong, WANG Chengyong
    China Mechanical Engineering    2022, 33 (05): 551-559.   DOI: 10.3969/j.issn.1004-132X.2022.05.003
    Abstract160)      PDF (7443KB)(87)       Save
    In view of the lack of relevant research on chip formation and tool wear mechanism in high-speed cutting of hardened steel under cryogenic liquid nitrogen cooling, a high-speed cutting of hardened steels under liquid nitrogen cooling was studied and compared with dry cutting. The cutting force, cutting temperature, characteristics of chip and tool wear were analyzed, and the mechanism of cooling and lubrication, chip formation and tool wear were discussed. The results show that compared with dry cutting, the cutting temperature of cryogenic liquid nitrogen cooling cutting is reduced by 6.9%-9.9%, and the cutting force is increased by 10.1%-12.8% due to material hardening. Compared with dry cutting, chip serration increases obviously under cryogenic liquid nitrogen cooling, which is related to the larger stress and strain in the first deformation zone and the transition from thermoplastic shear instability to periodic brittle fracture in chip formation. Cryogenic liquid nitrogen reduces cutting heat generation in cutting interfaces, the strong jet of liquid nitrogen blows away the chips, and the strong heat transfer capacity quickly take away the heat in the cut areas. Compared with the dry cutting, cryogenic liquid nitrogen may significantly reduce the adhesive wear, alleviate the tool micro-spalling by cooling and strengthen the tool, and improve the tool life by 28.6%-47.1%. Under cryogenic liquid nitrogen cooling conditions, adhesion is no longer one of the main wear mechanism, abrasive wear and impact wear are the main wear mechanism, and flank flaking and micro collapse blade are the main tool damage forms.
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    A New Method for Optimal Distribution of Kinematic Accuracy of Mechanical Transmission Systems
    LI Jian, RAN Yan, ZHANG Genbao, WANG Yongqin
    China Mechanical Engineering    2022, 33 (09): 1034-1043.   DOI: 10.3969/j.issn.1004-132X.2022.09.003
    Abstract158)      PDF (2446KB)(123)       Save
    In order to distribute the kinematic accuracy of mechanical transmission system reasonably, a new method for optimal distribution of kinematic accuracy of mechanical transmission system was proposed with the meta-action theory. Firstly, the “function-kinematic-action” structural decomposition tree was used to decompose the mechanical system, and then the basic meta-action and meta-action chain were obtained. Secondly, taking the meta-action chain as research object, the formation mechanism of kinematic accuracy was analyzed, and the kinematic error transfer model was established. Considering cost factors and sensitivity factor of kinematic errors, cost function and robustness function were established. Then the optimal distribution model of the kinematic accuracy of the meta-action chain was established, and the kinematic errors of the meta-action were obtained. An engineering example proved the effectiveness of the method.
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    Research Progresses on Surface Integrity of Bearing Grooves
    WANG Dongfeng, YUAN Julong, WANG Yanshuang, CHENG Yongjie, LYU Binghai
    China Mechanical Engineering    2022, 33 (18): 2143-2160.   DOI: 10.3969/j.issn.1004-132X.2022.18.001
    Abstract158)      PDF (5702KB)(136)       Save
    Improving the surface integrity of bearing grooves was an important solution to solve technical problems such as low reliability life, high friction power consumption and unstable vibrations and noises of bearings. On the basis of comprehensive research of generalized surface integrity by domestic and foreign scholars, the definition and connotation of characteristic parameters of bearing groove surface integrity were proposed, and the significance of characteristic parameters and the influence mechanism on bearing performance were expounded. The influences of different processing processes such as forging, turning, heat treatment, grinding and ultra-precision on the surface characteristic parameters of bearing raceways were analyzed in details, and the corresponding control measures were given. The new technologies, new processes, and new methods for improving surface integrity were briefly introduced. Finally, the summary and prospect of improving the surface integrity of bearing grooves were made to provide some references for improving the contact fatigue lifes of bearings.
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    Scale Thorn Formation Regularity and Inhibitory Measures in Cryogenic Cutting Processes of Aluminum Alloy 7075
    LIU Xiao, DENG Wenjun, CHEN Haitao, ZHANG Baoyu
    China Mechanical Engineering    2022, 33 (03): 261-269.   DOI: 10.3969/j.issn.1004-132X.2022.03.002
    Abstract157)      PDF (14895KB)(153)       Save
     Aiming at the problems of dry cutting aluminum alloys that were prone to scale thorns and poor surface integrity under low and medium cutting speeds, the orthogonal cutting experiments of aluminum alloy 7075 were carried out at different machining parameters using liquid nitrogen. The surface topography of workpieces and distribution of scale thorns were analyzed through scanning electron microscope, and the dimensions of scale thorns were measured by 3D surface profiler accurately. The effects of cutting speeds, feed rates, rake angles and cooling strategies (dry cutting, liquid nitrogen cooling, cutting fluid) on the distributions and sizes of scale thorns were analyzed. Based on the formation theory of scale thorns, the effects of machining parameters and liquid nitrogen cooling on the formation processes of scale thorns were discussed. Accumulated metals were a necessary and sufficient condition of the formation of scale thorns, and might be inhibited by improving tribological properties between chip and rake face. The results show that high cutting speed, low feed rate and large tool rake angle may reduce the thickness of accumulated metals, and inhibit the formation of scale thorns. Under cryogenic cutting conditions, the distribution density and size of the scale thorns are less than that of dry cutting, and a finishing surface topography of workpieces may be obtained.
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    Modeling Analysis of Key Friction Pairs in Low-speed Marine Diesel Engines and Verification of Friction Force Based on Wireless Measurement
    LI Rui, MENG Xianghui, XIE Youbai
    China Mechanical Engineering    2022, 33 (04): 380-387,396.   DOI: 10.3969/j.issn.1004-132X.2022.04.001
    Abstract152)      PDF (7506KB)(95)       Save
    Tribological properties of low-speed marine diesel engines possessed an important impact on the economy, safety, and stability of ship operations. However, there were few theoretical and experimental studies on the tribology of the engines. The modeling of key friction pairs were realized, and the friction was verified by wireless measurement herein. Firstly, combined with multi-body dynamics and mixed lubrication theory, the tribo-dynamics model of key friction pairs was established. Then, a wireless measurement method of friction force was proposed based on the idea of indirect measurement, and a measurement system was developed to realize the on-line measurement of friction forces under fired conditions. The results show that the simulation results of the friction are consistent with the experimental ones, and the maximum friction errors between the simulation and the experiments are less than 5%. The simulation load of the crosshead bearing is also in good agreement with the experimental load. In addition, for the system oil consumption of the stuffing box, the errors between simulation results and test ones are less than 3%. The results show that the modeling and measurement methods are feasible, and may provide support for tribological design, energy conservation and emission reduction of low-speed marine diesel engines. 
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    Research Progresses on Surface Roughness Model of Brittle Material Machining
    MA Lianjie, LI Hongshuang
    China Mechanical Engineering    2022, 33 (07): 757-768.   DOI: 10.3969/j.issn.1004-132X.2022.07.001
    Abstract151)      PDF (3344KB)(129)       Save
    Many factors affected surface roughness. Unique properties of brittle materials made the surface formation mechanism of brittle materials more complex, which made the machining quality difficult to control. By constructing the model of surface roughness, the surface roughness was predicted, and the machining quality might be controlled. In order to better reference the previous research results, characterization parameters of surface roughness were summarized herein. The methods used to establish the surface roughness model were constructed. The main research schools of the model and their development history, main academic contributions, and characteristics of the model were analyzed and summarized in detail. Finally, the future research direction of surface roughness model construction was prospected.
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    Metal Defect Image Recognition Method Based on Shallow CNN Fusion Transformer
    TANG Donglin, YANG Zhou, CHENG Heng, LIU Mingxuan, ZHOU Li, DING Chao
    China Mechanical Engineering    2022, 33 (19): 2298-2305,2316.   DOI: 10.3969/j.issn.1004-132X.2022.19.003
    Abstract150)      PDF (8847KB)(107)       Save
    Aiming at the problems of large amount of parameters and calculation in the field of metal defect recognition, a metal defect recognition method was proposed based on shallow CNN and Transformer model. The shallow CNN was used to learn the local information and position information of the images, and the Transformer was used to learn the global information of the images. At the same time, the channel attention module SE was introduced to pay attention to the important feature channels to realize the defect image recognition. The effectiveness of this method was verified by introducing the open defect data set, and the universality of this method was verified by using the self-built defect ultrasonic data set. The experimental results show that the proposed method has strong universality and may effectively identify metal defect images on small and medium-sized data sets. 
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    Deployable Waterbomb Wheel Structure Analysis and Optimization of Mine Rescue Robots
    SHANG Zuen, ZHAO Lijuan, LIU Xionghao, JIN Xin
    China Mechanical Engineering    2021, 32 (24): 2924-2933.   DOI: 10.3969/j.issn.1004-132X.2021.24.004
    Abstract149)      PDF (11377KB)(190)       Save
    A waterbomb wheel structure used in the coal mines rescue robots was designed to improve working reliability under complex conditions and adaptability to unstructured environments. A structural radial kinematics modeling method of the waterbomb wheel structure with the parallelogram as basic units was proposed to study the influences of different basic units on the waterbomb wheel structure's load-bearing characteristics. Based on the theory of continuum damage mechanics, the fatigue life of the parallelogram waterbomb wheel structures under axial compression loads was predicted. The design parameters of the waterbomb wheel were optimized by multi-objective optimization using the folding ratio as restrictions, with ultimate bearing capacity and fatigue life as evaluation functions. The research results show that the parallelogram waterbomb wheel has a better ultimate bearing capacity under the same mass. The optimized waterbomb wheel's folding ratio, the ultimate bearing capacity, the fatigue life prediction value has increased by 15.8%, 40.7%, 55.4% respectively, the working reliability of the waterbomb wheel structure is improved, and the actual fatigue life failure area is consistent with the theoretical calculation result. The experimental results verify the accuracy of the analysis processes and the effectiveness of the optimization method.
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    Review of Management for Mechanical Design and Manufacturing Discipline of NSFC in 2021
    China Mechanical Engineering    2022, 33 (06): 631-638.  
    Abstract146)      PDF (2554KB)(207)       Save
    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. 
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    Research on Dry Etching Processes on PSSs
    HOU Xiang, LIU Yixin, ZHONG Mengjie, LIN Sai, LIU Yang, LUO Ronghuang, LUO Xuetao, ZHANG Sa,
    China Mechanical Engineering    2021, 32 (24): 3001-3007.   DOI: 10.3969/j.issn.1004-132X.2021.24.014
    Abstract145)      PDF (4253KB)(64)       Save
    In order to shorten the etching time and improve the luminescence performance of the light-emitting diodes(LEDs), the dry etching processes of adding etching auxiliary gas trifluoromethane(CHF3) were studied. The effects of the bias power, the CHF3 flows and the degree of throttle butterfly pendulum auto pressure control valve(abb. APC) on the etch selectivity and the etch rate were investigated by orthogonal experiments during the inductively coupled plasma(ICP) dry etching processs. The experimental results show that the process has higher etch selectivity and etch rate when the bias power, the CHF3 flows and the APC is as 350 W, 15 sccm and 55%, respectively. The PSSs with large size, high pattern-sapphire ratio and small radian were obtained, compared with the conventional PSSs, the height and the pattern-sapphire ratio of optimized PSSs are improved by 5.6% and 4.6%, respectively.
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    Research Status of Key Technologies for Energy Management System of Marine Hybrid Propulsion Systems
    SUN Xiaojun, SONG Enzhe, YAO Chong
    China Mechanical Engineering    2022, 33 (04): 469-481,495.   DOI: 10.3969/j.issn.1004-132X.2022.04.010
    Abstract144)      PDF (4818KB)(114)       Save
    In the face of energy shortage and strict emission regulations, the use of new hybrid power system would become an important direction of ship development in the future. Firstly, the challenges were analyzed by the shipping industries, and the advantages and necessity of marine hybrid power were expounded. The topology and implementation framework of energy management systems were presented. Secondly, the research status of energy management strategy was analyzed, and the development route of hybrid system multi energy coupling energy management strategy was put forward. The challenges faced by the research and development of energy management strategies for marine hybrid power systems were explored , and  the future development trends and in-depth research directions were looked forward. The paper provides the research and development directions for the green and intelligent development of marine hybrid powers. 
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    Applications of Microfluidic Technology in Cross-domain of Mechanical Engineering and Life Science
    MAN Jia, HUA Zesheng, XIA He, LI Jianyong, LI Fangyi, LI Jianfeng,
    China Mechanical Engineering    2022, 33 (15): 1857-1868.   DOI: 10.3969/j.issn.1004-132X.2022.15.012
    Abstract144)      PDF (9998KB)(33)       Save
    Taking microfluidic technology as the research object, the preparation materials and technology of microfluidic chips were introduced, and the applications of microfluidic chip technology in the cross fields of life science were emphasized. It was mainly introduced from three aspects:biological detection, bionic fabrication of in vitro structure and preparation of controllable drug carriers, and the key technologies involved were discussed from the aspects of chip structure design and preparation, functional module integration, process regulation and so on. The application prospect of microfluidic technology in the fields of cross-domain between mechanical engineering and life science was prospected. 
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    Fault Diagnosis Method of Rolling Bearings Based on Improved Multi-linear Principal Component Analysis Network 
    GUO Jiaxin, CHENG Junsheng, YANG Yu,
    China Mechanical Engineering    2022, 33 (02): 187-193,201.   DOI: 10.3969/j.issn.1004-132X.2022.02.008
    Abstract143)      PDF (3991KB)(132)       Save
    The measured rolling bearing vibration signals were usually interfered by noises and had nonlinear and non-stationary characteristics, while multi-linear principle component analysis network(MPCAnet)had poor nonlinear fitting ability and poor feature clustering ability when dealing with complex non-stationary data. An improved multi-linear principal component analysis network was proposed by introducing kernel transformation, which increased the degree of difference among the training samples, further enhanced the generalization ability and classification accuracy when dealing with non-linear data. It is proved that this method has high robustness in different fault diagnosis data sets of rolling bearings and may accurately identify various faults of rolling bearings. 
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    Calibration Method for Cable-driven Continuum Robots
    LI Famin, ZHENG Tianjiang, SHEN Wenjun, WANG Huixiao, FANG Zaojun, LIANG Dongtai
    China Mechanical Engineering    2022, 33 (02): 202-208.   DOI: 10.3969/j.issn.1004-132X.2022.02.010
    Abstract142)      PDF (4575KB)(125)       Save
    In order to improve the positioning accuracy of the cable-driven continuum robots, an error calibration and compensation method was proposed for the cable-driven continuum robot modules(CDCRMs). The product-of-exponential(POE) formula was employed to develop the kinematics model for the CDCRMs. The kinematics error transfer model was derived through the kinematics model, which was used to identify the kinematics errors by using the least-squared algorithm. Identified errors were used to compensate the kinematics model, thus the accuracy of the CDCRMs was improved. A prototype of a CDCRM with a flexible backbone was made to verify the calibration algorithm by simulation and experiments. The results show that the position accuracy of the CDCRMs is improved by 32.23% and the orientation accuracy is improved by 81.64%, which prove the effectiveness of the calibration algorithm.
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    Road Roughness Recognition Based on Vehicle Body Dynamic Response of Tracked Vehicles
    LING Qihui, DAI Juchuan, CHEN Shengzhao, SUN Feiying, WANG Guosheng, LIAO Lili
    China Mechanical Engineering    2022, 33 (01): 62-69.   DOI: 10.3969/j.issn.1004-132X.2022.01.007
    Abstract140)      PDF (5986KB)(113)       Save
    A model for road surface roughness recognition was established based on dynamic response of tracked vehicle body. NARX neural network structure was adopted in the model, and dynamic response signals of tracked vehicle body were taken as inputs and road surface roughness values were taken as outputs. Correlation coefficient, root mean square error, and absolute error cumulative probability density were proposed as indexes of recognition effectiveness evaluation, and the fusion method of the three indexes was proposed. Based on orthogonal experimental design, the balance between the number of input and the recognition effectiveness of road roughness recognition model was analyzed and realized, which simplified the layout of the sensor test system. The recognition effectiveness of road roughness under different road surfaces, different sampling frequencyies, and different speeds was analyzed. The results show that the proposed model may satisfy the practical engineering needs.
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    Research and Applications of Condition Monitoring and Predictive Maintenance of Marine Diesel Engines
    CHEN Dongmei, ZHAO Siheng, WEI Chengyin, CHEN Yajie
    China Mechanical Engineering    2022, 33 (10): 1162-1168.   DOI: 10.3969/j.issn.1004-132X.2022.10.004
    Abstract139)      PDF (3080KB)(291)       Save
    Based on the four dimensions of thermal-pressure parameters, lubricant oil conditions, vibrations and cylinder pressures, data acquisition and feature extraction were carried out, and a method for diesel engine condition monitoring was proposed based on OCSVM anomaly detection algorithm and Fisher discriminant analysis.  The CUSUMMR was used for parameter trend detection and the D-S evidence theory and weight of evidence method were used for multi-source information fusion. the RUL(remaining useful life) of diesel engine lubricating oil was predicted by LSTM. The Paper solves the problems such as low early warning rate, poor adaptability of the model under diesel engine dynamic conditions. 
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    Design of Soft Robots for Hand Function Rehabilitation Training
    CONG Ming, BI Cong, WANG Minghao, LIU Dong, DU Yu
    China Mechanical Engineering    2022, 33 (08): 883-889.   DOI: 10.3969/j.issn.1004-132X.2022.08.001
    Abstract137)      PDF (7250KB)(117)       Save
    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. 
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    Related Parallel Machine Online Scheduling Method Based on LSTM-PPO Reinforcement Learning
    HE Junjie, ZHANG Jie, ZHANG Peng, WANG Junliang, ZHENG Peng, WANG Ming
    China Mechanical Engineering    2022, 33 (03): 329-338.   DOI: 10.3969/j.issn.1004-132X.2022.03.009
    Abstract137)      PDF (6559KB)(130)       Save
    To solve the related parallel machine online scheduling problems, the total weighted completion time was taken into account, and an online scheduling method was proposed based on LSTM-PPO reinforcement learning. A LSTM-integrated agent was designed to record the historical variations of workshop states and the corresponding scheduling policy adjustment, and then online scheduling decision was made according to the state information. Meanwhile, the workshop state matrix was designed to describe the problem constraints and optimization goals, additional machine waiting was introduced in scheduling action space to expand solution space, and the reward function was designed to decompose the optimization goal into step-by-step rewards to achieve scheduling decision evaluation. Finally, the model updating and global optimization of parameters was achieved by PPO algorithm. Experimental results show that the proposed method has competitive solutions than the existing heuristic rules, and the proposed algorithm is applied to the production scheduling of the actual workshops, which effectively reduces the total weighted completion time.
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    Design Optimization for Hydraulic Systems of Forklift Boom Based on Deep Surrogate Model
    LIN Jingliang, HUANG Yunbao, LI Haiyan, ZHOU Sheng, HUANG Zeying
    China Mechanical Engineering    2022, 33 (03): 290-298.   DOI: 10.3969/j.issn.1004-132X.2022.03.005
    Abstract137)      PDF (6175KB)(154)       Save
    To improve the performance of using fine-tune to construct deep neural network surrogate models(named also by DSMs), an active closed-loop Monte Carlo method for design of experiments was presented. The design point was associated with the model gradient through Fisher information matrix, and solved by multiplication algorithm. A random-discretization based Monte Carlo algorithm was then given for closed-loop sampling, so that the design points had the statistical characteristics covering the entire design space. Based on this method, a DSM of action characteristics of a telescopic forklift was constructed with multilayer perception, and combined with minimizing the predictor and expected improvement to realize the design optimization of the hydraulic control systems. Experimental results show that compared with the benchmarks, the simulation data required by the proposed method is reduced by 64.3%. The pressure fluctuation of luffing cylinders for the optimized forklift booms is more stable, and the maximal value is decreased by 46%.
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    Information Extraction Method of Part Machining Features Based on Image Deep Learning
    ZHANG Shengwen, ZHOU Xi, LI Bincheng, CHENG Dejun, CHEN Wendi
    China Mechanical Engineering    2022, 33 (03): 348-355.   DOI: 10.3969/j.issn.1004-132X.2022.03.011
    Abstract137)      PDF (5249KB)(167)       Save
    Aiming at the information integration problems for machining features of various part models based on model definition(MBD), a holographic information extraction method of machining features was proposed based on multi-level extraction architecture. Through the analysis of structural characteristics of parts, the machining features were classified with the simplest features that had manufacturing semantics and could not be split. Based on elaborating the extraction strategy, a machining feature classifier was built by deep learning image recognition technology. Based on the characteristics of MBD model information annotation, the machining feature topology structure was quickly located and extracted. A multi-view capture dimensionality reduction method was used to make the machining feature color image. And then a comprehensive analysis method for multi-angle image recognition of machining features was designed. Based on the query views, the annotation information of the MBD models was filtered, and a double-layer filtering extraction method for machining feature geometric information was constructed. Finally, a holographic information extraction software for machining features was established, and experimental results of key parts of marine diesel engines show the effectiveness of the method. 
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    Robot Kinematics Calibration Method Considering Base Frame Errors
    NI Huakang, YANG Zeyuan, YANG Yifan, CHEN Xindu, YAN Sijie, DING Han
    China Mechanical Engineering    2022, 33 (06): 647-655.   DOI: 10.3969/j.issn.1004-132X.2022.06.003
    Abstract137)      PDF (4061KB)(140)       Save
    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. 
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    Research on Mode Switching Control Strategy of Marine Diesel/Natural Gas Dual Fuel Engines
    SONG Enzhe, JIANG Zhongzhou, YAO Chong, ZHAO Guofeng
    China Mechanical Engineering    2022, 33 (04): 388-396.   DOI: 10.3969/j.issn.1004-132X.2022.04.002
    Abstract136)      PDF (4803KB)(71)       Save
    In the actual operations of marine diesel/natural gas dual-fuel engines, switching between pure diesel mode and dual-fuel mode might easily cause large engine speed fluctuations and unstable operations, which endanger the normal operations of the engines. In addition, in some emergencies(such as insufficient natural gas fuel, sudden load unloading, et al), the engine needed to switch between different modes quickly and smoothly. In response to the demands, a rule-based dual-fuel engine mode switching control strategy was designed based on the operating requirements and mechanism of the dual-fuel engine under the premise of the same control system hardware. Among them, the diesel-to-dual-fuel mode adopted the reverse control method, and the dual-fuel-to-diesel mode was divided into active switching and passive switching to respond to different control requirements. The designed switching control strategy realized the mutual switching of different fuel modes based on experimental calibration data and software algorithms. Finally, an experimental platform was built to verify different operating conditions mode switching control performance based on the YC6K dual-fuel engine. The results show that the designed switching strategy satisfies the switching control requirements under various working conditions, and improves the running performance of the whole machine. 
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    Prediction and Experimental Study of Critical Cutting Speed of White Layer Formation in LAT Hardened Steels
    XIE Xingjie, ZHANG Xiaojian,
    China Mechanical Engineering    2022, 33 (01): 15-23.   DOI: 10.3969/j.issn.1004-132X.2022.01.002
    Abstract136)      PDF (7975KB)(96)       Save
    It was easy to produce a white layer on the machined surfaces of hardened steels, which had a serious impact on service performance of parts. To solve the problems of white layer formation, LAT was therefore proposed to replace conventional turning for hardened steels. FEM of thermal-mechanical coupling LAT processes was established by VDFLUX user subroutine. Based on simulation results of FEM and prediction model of critical cutting speed of white layer formation, the influences of different laser preheating parameters on critical cutting speed of white layer formation were analysed. The results show that the upper limit of the critical cutting speed of white layer formation may be increased by appropriately reducing laser power, increasing laser spot radius, and shortening the distance from laser spot to tool tip within the ranges of laser preheating parameters selected, such as laser power P is as 200~600W,laser spot radius R is as 0.5~0.9 mm,distance between laser spot and tool tip L is as 5~15 mm. Under the optimized laser preheating parameters(P=200 W, R=0.9 mm, L=5 mm), the critical cutting speed of white layer formation on the machined surfaces of hardened steels is higher than that of conventional cutting to about 26.09%.
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