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  • WU Qilin, ZHAO Han, CHEN Xiaofei, ZHAO Yating
    Journal of Mechanical Engineering. 2023, 59(15): 1-16.
    As labour shortages and labour costs continue to rise, more and more robots are needed in growing numbers. In many application scenarios, the tasks are complex and varied, the application environment and the conditions are so varied that single-arm collaborative robots are no longer meet the requirements and multi-arm collaborative robotic systems have emerged as an important area for future development. Because of the short time frame for development, a great deal of work is still needed by developers. This research summarizes the current state of technology and applications of multi-arm collaborative robots in a more systematic way and reviews several influential aspects of multi-arm collaborative robots such as applications, mechanism and lightweight, dynamics and control, cooperative technology, and artificial intelligence. On this basis, six directions for future research and development of multi-armed collaborative robots are proposed, based on new developments in artificial intelligence and control, such as the development of application scenarios towards deep human-robot collaboration, more emphasis on high speed, high precision and high work-to-weight ratio in structures and components, and more emphasis on smooth design in dynamics. The collaborative robot system will also develop in a hierarchical and diversified manner, with control methods tending towards adaptive and flexible control and autonomous decision-making, and interaction tending towards multi-dimensional safety protection and natural interaction with multi-information fusion.
  • SHA Jingwei, FAN Mengbao, CAO Binghua, YANG Xuefeng
    Journal of Mechanical Engineering. 2023, 59(24): 1-17.
    The hardness of metallic components is a crucial indicator of their mechanical and physical properties, making hardness testing an important aspect of industrial production. Traditional methods of hardness testing, such as indentation or scratch tests, suffer from issues such as high destructiveness and low efficiency, rendering them unsuitable for modern testing needs. Therefore, non-destructive testing methods have emerged as a research hotspot. With the development of acoustic and electromagnetic technologies, non-destructive hardness testing techniques based on these technologies have been developed. Herein, a systematic description of non-destructive hardness testing techniques based on acoustic and electromagnetic methods is presented, and the influence of different material microstructural changes on the detection characteristics is explored. Through an analysis of the relationship between characteristics and microstructural changes, a deeper understanding of the principles and applications of non-destructive hardness testing techniques is gained. Subsequently, novel signal processing methods based on neural networks are reviewed, which have shown great potential in improving detection accuracy and optimizing signal processing algorithms. Finally, future development trends of non-destructive hardness testing techniques are discussed.
  • Li Fei, Zhang Huayu, Chen Huiqin
    Forging & Stamping Technology. 2023, 48(8): 231-237.
    The mechanical behavior and microstructure evolution of Mn18Cr18N steel under cycle loading in the strain amplitude range of±0.005-±0.10 were studied by room temperature tension-compression cycle loading tests. The microstructure evolution of Mn18Cr18N steel, including metallographic structure, dislocation morphology, deformation twins and other substructures, were observed by optical microscope and transimision electron microscope. The research results show that the cyclic mechanical properties of Mn18Cr18N steel are related to the strain amplitudes in the tension-compression cycle loading. With the increasing of cyclic strain amplitude, the cyclic stress amplitude of Mn18Cr18N steel shows an increasing trend. When the strain amplitude is ±0.10, the rheological stress of Mn18Cr18N steel is 988.1 MPa after one cycle loading, which is 1.6 times of the 0.2% initial yield strength. The research indicates that the cumulative plastic strain of Mn18Cr18N steel is increased by the cycle loading with large strain amplitude to significantly improve the strength. At a lower strain amplitude (±0.005-±0.01), the deformation of Mn18Cr18N steel is mainly plane slip, and the dislocation rearrangement and the activation of other slip systems are the main reasons for the cycle softening of Mn18Cr18N steel. When the strain amplitude is larger, the proliferation of high dislocation increases the internal stress of the matrix, the local area slips difficultly, the twinning mechanism is activated, and Mn18Cr18N steel generally exhibits cycle strengthening characteristics.
  • YU Zhihui, LIANG Jun, WU Dechao, LIU Jiguang, WANG Yuanxian
    China Foundry Machinery & Technology. 2023, 58(4): 63-68.
    Based on the structural characteristics and relevant casting technical requirements of an HT200 headstock, the corresponding casting process parameters have been determined through structural and process analysis of the casting, while the preliminary design of the pouring system has been completed.The pouring, filling, and solidification processes of molten metal have been simulated by use of computer software.By setting and adjusting the size and position of the riser and cold iron, the shrinkage porosity and porosity defects in the casting have been significantly reduced, while the optimal casting process plan has been obtained.
  • WANG Shuancheng, YANG Bing, LIAO Zhen, XIAO Shoune, KANG Guozheng, YANG Guangwu, ZHU Tao
    Journal of Mechanical Engineering. 2023, 59(16): 32-53.
    The short fatigue cracks of metal materials are systematically sorted out in terms of their definition, classification, test methods, initiation mechanism, and typical growth rate models, as well as the problems facing the current research on short crack behavior, are summarized and prospected. The results show that the microstructure of materials plays an important role in the initiation and propagation of short cracks. When the crack tip reaches the grain boundary, the growth rate of cracks decelerates due to the influence of grain orientation and grain boundary resistance, and the short crack propagation path appears to be locally deflected after the crack tip breaks through the grain boundary constraint. In terms of the short cracks propagation behavior description, the driving force of short crack propagation is related to the load level, residual stress, surface treatment and local wear condition, and so on. During propagation, the crack tip materials yield in a small area and produce a local plastic zone. At the same time, the plastic wake is gradually formed, which results in plastic-induced closure and a decrease in the crack propagation threshold value. Besides,the interaction between crystal dislocations and dislocation stacking can hinder the dislocation development. The machine learning algorithm, as an advanced technological tool, has been applied in the characterization of short crack growth behavior, which has contributed to the improvement of prediction accuracy. With further research on the behavior of short cracks in metal materials, we can focus on real-time monitoring of short crack initiation and propagation, control of test influencing factors, discrete data analysis,and engineering applications of the growth rate model in the future. The establishment of a unified characterization model for long and short crack growth rate as well as real-time monitoring and safety assessment techniques will be explored. In addition, more effective and accurate safety assessment and remaining life management of critical metal structures can be realized by combining advanced machine learning algorithms.
  • ZHANG Lei, XU Tongliang, LI Siyang, CHENG Shuhui, DING Xiaolin, WANG Zhenpo, SUN Fengchun
    Journal of Mechanical Engineering. 2023, 59(20): 261-280.
    Chassis coordinated control for full X-by-wire distributed-drive electric vehicles can effectively enhance both safety and ride comfort during vehicular operation. Taking vehicle safety and ride comfort as objectives, this paper provides a comprehensive review of key technologies and challenges in the chassis coordinated control for full X-by-wire distributed-drive electric vehicles, encompassing handling stability control, fault-tolerant control, vehicle attitude control, and ride comfort control. For handling stability control, traction control and anti-lock braking methods are introduced. A systematic analysis is conducted to evaluate the advantages and disadvantages of using one single or multiple X-by-wire subsystems in lateral and roll vehicle stability control. Regarding fault-tolerance control, the paper outlines fault-tolerant control strategies that use direct yaw-moment control to complement steer-by-wire systems. The paper summarizes methods for pitch attitude control and ride comfort control using one single or multiple X-by-wire subsystems. It emphasizes the importance of simultaneously addressing vehicle attitude and ride comfort to enhance control adaptability in complex operating conditions. Finally, the paper provides insights into future directions in chassis coordinated control.
  • CHEN Xuedong, FAN Zhichao, CHEN Yongdong, XU Shuangqing, CUI Jun, ZHANG Xiaohu, GUAN Weihe, AI Zhibin
    Journal of Mechanical Engineering. 2023, 59(20): 18-33.
    Pressure vessel is a kind of pressure-bearing special equipment with a large quantity and wide applications, showing the potential hazard of leakage and explosion. China lists pressure vessels as high-end equipment, requiring to improve product quality and core competitiveness. Since the beginning of this century, scientific and technological workers in China have continued to carry out research and exploration and engineering practice in pressure vessel design and manufacturing under extreme conditions, lightweight green manufacturing of heavy-duty pressure vessels, risk-based integrity management, digital design, manufacturing and maintenance, etc. The applications of these achievements have made China’s petrochemical plant high-end pressure vessels basically no longer rely on imports, the level of green manufacturing technology has been significantly improved, and the long-term operation and maintenance capability has been significantly enhanced. This paper first briefly reviews the progress of pressure vessel design, manufacturing and maintenance technology in China since the beginning of this century. Focusing on major national strategies such as advancing new industrialization, moving faster to boost China’s strength in manufacturing and product quality, implementing industrial infrastructure reengineering projects and major technical equipment research projects, the technical problems that need to be solved urgently are elaborated from four aspects including robust industrial foundations, extreme manufacturing, green manufacturing and smart manufacturing. Facing the new application scenarios and the application of a new generation of artificial intelligence technology in the next two decades, the development trend of pressure vessels is technically foreseen.
  • Yuan Zhizhong, Wang Mengfei, Zhang Bocheng, Duan Xubin, Li Biaomin, Yang Haifeng, Luo Rui, Cheng Xiaonong
    Heat Treatment of Metals. 2023, 48(9): 1-7.
    SKD11 steel plate after hot rolling and spheroidizing annealing was used. Two kinds of complex phase heat treatment processes, A-Q-A (Austempering-Quenching-Austempering) and Q-T-A (Quenching-Tempering-Austempering), as well asconventional Q-T(Quenching-Tempering) heat treatment process were carried out. The effect of heat treatment process on the microstructure, hardness and impact absorbed energy was studied. The results show that the microstructure of the specimens after A-Q-A and Q-T-A is the combination of lower bainite (LB) and martensite (M). The content of retained austenite is 13.2% and 18.6% for A-Q-A and Q-T-A, respectively. After A-Q-A, Q-T-A and conventional heat treatment Q-T, the hardness of the specimens is 58.5, 58.6 and 60.5 HRC and the impact absorbed energy is 31.3, 27.6 and 15 J, respectively. The excellent combination of strength and toughness of the SKD11 steel plate is realized by the duplex-phase heat treatments, which does a beneficial exploration in improving the toughness of the cold working die steel.
  • GAO Yanjie, GAO Jianquan, PENG Jun, ZHANG Fang, WANG Yongbin, CHANG Hongtao
    China Foundry Machinery & Technology. 2023, 58(5): 39-45.
    Steel slag, as the main solid waste in the metallurgical industry, has a low overall utilization rate in China due to its large output and poor stability.The composition of hot pressed steel slag at Baotou Steel has been introduced in the text.The current main treatment processes and advantages & disadvantages in China have been elaborated, as well as the differences in composition, utilization rate, and main application manufacturers of steel slag under different treatment conditions.Based on the mineral phase and physical properties of steel slag, the current utilization status and usage pathways of steel slag both domestically and internationally have been elaborated, mainly including internal and external circulation of enterprises.Internal circulation of enterprises mainly includes the recycling of waste steel and the use of sintering materials.External circulation of enterprises mainly includes road construction and construction, agricultural fertilizer production and soil improvement, concrete, flue gas desulfurization, carbon dioxide absorption, and functional materials and related fields.In addition, aiming at the shortcomings in the current utilization of steel slag, the future development direction of steel slag has been expected.
  • MAI Ge-ma
    Foundry. 2023, 72(7): 937-938.
  • Research·Review
    Jin Xiaolei, Zhao Fei, Hao Xianchao, Xing Weiwei, Wang Min, Ma Yingche
    Special Casting & Nonferrous Alloys. 2023, 43(8): 1029-1035.
    Nickel-based alloys possess excellent thermal strength and service stability, which are the widely used for high temperature applications.Cobalt was initially added in the development of nickel-based alloys to improve alloy properties. However, the role of Co in nickel-based alloys is still controversial. Effects of Co on microstructure, precipitation characteristics of the γ' phase, stability and mechanical properties of nickel-based alloys were investigated, and Co action mechanism was analyzed from the aspects of effects and indirect effects.Moreover, the possibility of saving Co and replacing Co was explored, aimng to provide theoretical basis for the development of novel nickel-based alloys and application of nickel-based alloy containing Co.
  • ZHAO Sijie, YI Chuanming, XIAO Gang, DAI Luyi, ZHANG Ning, WAN Keqian, YANG Qinwen
    China Foundry Machinery & Technology. 2023, 58(5): 33-38.
    With the rapid development of the digital economy, the integration of additive manufacturing and digital twin technologies is an inevitable trend in the digital transformation of high-end manufacturing industry, which has attracted attention from all sectors of society.The origin, definition, and key technologies of additive manufacturing and digital twin technology have been summarized in the text.The system framework and application status of digital twin technology in the field of additive manufacturing have been analyzed.A system technology architecture based on the development of additive manufacturing digital twin products and their industry application requirements have been proposed.The key research directions and key technologies have been elaborated.The development trend and application prospects of additive manufacturing digital twin technology have been explored.This study provides innovative ideas for promoting the integration technology research of digital twins and additive manufacturing, as well as the development of applied products.
  • WU XiaoLi, LI ZhaoKai
    Journal of Mechanical Strength. 2023, 45(4): 826-837.
    In recent years, negative Poisson′s ratio (NPR) materials have attracted extensive attention from the academic community due to their excellent mechanical properties and huge application potential in traditional industrial fields.The mechanical properties of a new type of material with negative Poisson′s ratio (based on YSH structural cell) under dynamic compression are designed and studied.Through the finite element simulation method, the response difference of different structural parameters (inclined wall angle, width ratio, aspect ratio) to the equivalent elastic mechanical performance parameters of the cell is compared, and the influence of these structural parameters on the energy absorption performance is explored, and the research is further extended to the structure under four common functional gradient arrays.The energy absorption effect of the structure is evaluated by three indexes:energy absorption, energy absorption efficiency and platform stress.The study shows that, inclined wall inclination θ the larger, the better the energy absorption performance of the whole structure; width ratio α it has little influence on the equivalent mechanical properties and energy absorption of the whole structure; aspect ratio β the smaller the value, the more obvious the negative Poisson′s ratio effect of the structure, but on the contrary, the larger the value, the higher the energy absorption efficiency.The results can provide a reference for the function-oriented design of materials with negative Poisson′s ratio.
  • XIE Jiale, LI Zengchao, WANG Guang, YAO Tianqi
    Journal of Mechanical Engineering. 2023, 59(16): 342-352.
    The thermal safety of power batteries has been widely concerned by academia and industry. The temperature information of battery system is the essential reference to make efficient thermal management strategies. Specific to cylindrical batteries, lightweight lumped-parameter temperature prediction models are developed for embedded applications. Firstly, based on an equivalent circuit model, a mass-point(MP) temperature model is formulated according to basic electrical-thermal effects by regarding the cell as an isotropic homogeneous body. On this basis, the winding and shell parts of the cell are separately studied that surface heat dissipation,heat conduction delay and reversible heat are modeled in detail and related parameters are experimentally identified, thereby deriving an improved layered-divided(LD) temperature model to predict battery kernel(internal) and shell(external) temperatures. Finally,taking an 18650 li-ion battery as the object, experimental results under different temperatures and load conditions show that the temperature prediction performance of the LD model is obviously ameliorated in contrast to the MP model; the LD model can keep high reliability subject to various working conditions. Subject to hybrid pulse excitations, the max temperature error of the LD model is about 1 ℃ after 10 minutes of open-loop simulation.
  • ZHANG Rui, ZENG Xiangjin, XU Cheng
    Packaging and Food Machinery. 2023, 41(4): 96-101.
    For the problems of limited cargo information,collision and physical stability limitation in the 3D boxing problem,an online 3D boxing method based on constrained deep reinforcement learning was proposed.This method uses the improved heuristic search algorithm to predict the feasibility mask of placing actions,and uses this mask to adjust the action probability output by the policy network during training.The experimental results show that the algorithm improves the boxing efficiency of disordered mixed goods,the average placement time of a single cargo is only 3.9 ms,and the space utilization rate reaches 68%.The study provides a useful reference for the application of reinforcement learning in the field of combinatorial optimization.
  • Research·Review
    Yuan Zizhou, Lang Yapeng, Zhang Xiangyun
    Special Casting & Nonferrous Alloys. 2023, 43(8): 1036-1040.
    Bulk amorphous composites are a kind of structural material with excellent mechanical properties, which overcome the room-temperature brittleness of amorphous alloy and retain high strength. The investigation of superplastic deformation behavior in the supercooled liquid region can not only guide the establishment, development and perfection of theoretical model, but also accelerate the engineering application of materials.The research status on superplastic forming of bulk amorphous alloys as well as its composites were briefly introduced, focusing on the superplastic rheological behavior of bulk amorphous composites in the supercooled liquid region, microstructure evolution and variation of mechanical properties during superplastic deformation. Finally, some technical problems to be solved in superplastic forming of amorphous composites were put forward.
  • Plant Maintenance Engineering. 2023, 0(15): 160-162.
    主给水泵负荷随机组功率变化,泵轴轴系应力变化大,泵组对中情况在运行工况下变化大,泵组停运检修时建议复测检查对中数据,发现数据超出联轴器设计可补偿范围时,需警惕膜片联轴器膜片发生疲劳断裂。轴功率大于6 MW的泵组由于在运泵组本体设计和运行工况无法改变,泵组轴系膨胀情况无法改善,最终通过重新设计联轴器,选取2.7的选型工况系数,提高联轴器抗疲劳强度解决膜片断裂问题。
  • XU Hongniu, YU Huayun
    Modular Machine Tool & Automatic Manufacturing Technique. 2023, 0(9): 106-111.
    Many problems exist for the current target detection of aluminum sheet surface defects, including the unsuitability of large-scale algorithms and computing devices in the field, and the balance between detection speed and accuracy.In this paper, a novel lightweight detection method based on attention mechanism is proposed, focusing on industrial applications of aluminum sheet defect detection.The GBANet backbone network is proposed based on the YOLOv4 framework, which is constructed based on a new convolutional Ghost module and embeds an improved attention module in the stacked Ghost blocks.The neck network is redesigned and lightened by feature fusion, the perceptual field is increased, the network is simplified by the SPPF-PANet module and the accuracy of the model for defective objects is enhanced by measures such as improved anchor box and loss function.Experiments show that the proposed method improves the mAP by 1.06% compared with the original YOLOv4, achieves a detection speed of 36.6 fps, reduces the model volume by 82.72%, and can effectively identify different kinds of defects on the surface of aluminum profiles.The proposed method can meet the requirements of defect detection in the production site of aluminum profile factories.
  • LIN Xinyou, YE Zhuoming, ZHOU Binhao
    Journal of Mechanical Engineering. 2023, 59(16): 315-324.
    To solve the problem of autonomous steering of autonomous vehicles, most researches are mainly based on the model predictive control(MPC) strategy, while the traditional MPC strategy requires an accurate mathematical model of the controlled object and a lot of real-time control calculations. To this end, a steering control strategy based on deep Q-Learning neural network(DQN)reinforcement learning is proposed, which enables autonomous vehicles to track paths accurately and effectively, and improves the accuracy and stability of path tracking. The strategy is based on DQN reinforcement learning to train the agent by selecting an appropriate learning rate, so that the trained agent can adaptively obtain the best front wheel turning angle according to different road conditions and vehicle speeds. The simulation comparison results show that compared with the unconstrained linear quadratic regulator(LQR) control strategy, the cumulative absolute lateral position deviation and cumulative absolute yaw angle deviation of the control strategy based on DQN reinforcement learning have increased significantly. But it is also within an acceptable range, which can effectively improve the accuracy of path tracking. The final real vehicle test results also show the effectiveness of the proposed control strategy.
  • DING Mingna, LIU Xianli, YUE Caixu, FAN Mengchao, GU Hao
    Journal of Mechanical Engineering. 2023, 59(19): 429-459.
    With the rapid development of Intelligent Manufacturing Technology, the manufacturing industry is gradually realizing intelligent production. Especially for the extremely complex cutting process, the intelligentization is of great significance. As the most active element during the cutting process, the performance and life of cutting tool have a direct influence on the machining accuracy and production efficiency of parts. The diversity of material machinability, the nonlinear dynamic change of machining system and the variability of production rhythm have brought great challenges to the tool design, manufacturing, management and control technology. The Intelligent Manufacturing Technology makes the precise and efficient design, accurate and reliable manufacturing, as well as, scientific and comprehensive control of the tool oriented to the demand can be realized, which is conducive to the energy saving, consumption reduction, quality and efficiency improvement in the production process. The relevant technical framework of tool design, manufacturing, management and control oriented to intelligent manufacturing process is proposed. The relevant research results and application cases at home and abroad are summarized from three aspects: tool design method, manufacturing process, as well as, management and control technology for intelligent manufacturing. The tool design, manufacturing, management and control technology for the whole life cycle based on virtual-real mapping and iterative optimization is prospected. The intellectualization of tool's whole life cycle will help the upgrading and structure optimization of manufacturing industry, and promote the intelligent transformation of production mode.
  • DAI Jiajia, GONG Xiaoxi, WANG Jun
    Journal of Mechanical Engineering. 2023, 59(16): 243-253.
    A coverage path planning algorithm based on the improved WaveFront algorithm is proposed for the full coverage path planning problem of unmanned aerial vehicles(UAVs) in the 3D environment in aircraft inspection tasks. Investigating a method for extracting viewpoints on the surface of 3D models based on discrete 3D grid maps. Improving the WaveFront algorithm according to the constraint strategy of adjacent viewpoints to solve the local optimum problem caused by the same loss value in different directions.Designing the orientation evaluation function in 3D space, which, combined with the viewpoint position, can guide the forward direction of the UAV. Realizing the UAV coverage path planning based on the 3D model for the aircraft surface. The experimental results show that the algorithm can realize the automatic extraction of viewpoints on the aircraft surface, and combined with the viewpoints can autonomously plan the flight path of the UAV. Compared with the genetic algorithm, the improved WaveFront can effectively carry out path planning on the aircraft surface and ensure that the UAV maintains a collision-free state with the aircraft fuselage. According to the planned path, the UAV can complete the task of detecting the surface of the aircraft fuselage without omission.
  • Liu Fei, Xu Shuhui, Wang Xiaoting, Wang Xinzhuo, Feng Mengyu
    Forging & Stamping Technology. 2023, 48(8): 176-184.
    In order to suppress the vibration in vertical direction of four-roll strip mill, firstly, considering the segmental nonlinear elastic force under the influence of dynamic clearance, the dynamic model of rolling mill roll system under the joint action of segmental nonlinear elastic force and dynamic rolling force was established, and the amplitude-frequency characteristic equation of the system was solved by using the average method. Then, the time-domain characteristics and frequency characteristics of the roll system when the elastic modulus of hydraulic oil changes were simulated with the actual parameters of rolling mill, and the influence laws on the vibration behavior of the roll system was obtained. Furthermore, the change laws of the amplitude-frequency response of the roll system under different hydraulic system parameter changes were compared, the influence of the hydraulic cylinder parameter change on the vibration behavior of the system was analyzed through the bifurcation characteristics, and the parameter interval was obtained when the system cycle was running stable.Finally, a state feedback controller was designed to realize the vibration control of the dynamic clearance rolling mill roll system. The analysis of amplitude-frequency characteristics and bifurcation characteristics shows that the controller can effectively weaken the influence of the dynamic clearance on the stability of rolling mill roll system, and suppress the chaotic behavior of the roll system, which provides a theoretical reference for suppressing the vibration of rolling mill roll system.
  • LYU Shufan, DU Yuhong, LIU Tong
    Machine Tool & Hydraulics. 2023, 51(14): 113-117.
    In order to measure the friction torque of bearings at different temperatures,a new type of bearing friction torque measurement equipment was designed based on the measurement principle of the transfer method.The process hole in the lower layer of the incubator in the equipment was sealed with a sealed structure,and in view of the impact problem generated by the tested bearing and the measuring spindle during the docking,a new type of rat-like detachable clamp was designed to achieve a smooth transition.LabVIEW was used to write related motion control,data acquisition,and control interface programs.After the program was calculated and processed,the bearing friction torque value,change curve and other data were obtained.Finally,this equipment was used to measure the friction torque of SKF7207 deep groove ball bearings.The results show that the maximum repeatable measurement error of the equipment is 0.000 49 N·m,which has good repeatability and meets the design requirements.
  • PENG Ling, ZHU Runze, DAI Kunlin, LI Hanchao, ZOU Qing, SHEN Shuli
    Machine Tool & Hydraulics. 2023, 51(18): 152-156.
    Industrial robot language is an important part of the robot control system and is a window for users interacted with robot.Aiming at the problems that expanding hard and program editing operation is not efficient for existing industrial robot language editor,a design scheme for industrial robot language editor was proposed based on Qt.This editor provided loading,creating,copying,selecting of robot operating procedures and editing,copying,pasting,deleting of instruction lines.In addition,in order to take into account of the safety of robot operation,parameter range check and logic check of robot instructions were added.These functions were integrated in the teach pendant "program" menu module.It is verified that the proposed robot language editor has good portability and expansibility by the way of testing on real machine.
  • WANG Xue-qing, XIAO Xiao, MENG Ling-ran, ZHANG Chi, ZHANG Shuai-feng, GE Xue-yuan
    Transactions of Materials and Heat Treatment. 2023, 44(8): 1-15.
    As one of the most promising lightweight structural materials, magnesium alloys have excellent castability, machinability, biocompatibility and excellent mechanical properties, and have been widely used in many fields such as automotive manufacturing, aerospace, and biomedicine. With the demand onlightweight, the development of magnesium alloy integral components has become an emerging trend. However, the integral components usually have the characteristics of large scale and complex structure. Compared with traditional manufacturing processes, wire and arc additive manufacturing has the characteristics of high deposition rate, low cost, and high material utilization rate, providing the possibility to prepare large magnesium alloy components. Therefore, the wire and arc additive manufacturing of magnesium alloy has received a lot of attentions. This article mainly summarizes the research progress in wire and arc additive manufacturing of magnesium alloy from three aspects. Firstly, different process methods of wire and arc additive manufacturing technology are introduced; secondly, the research status of wire and arc additive manufacturing of magnesium alloy is introduced, including molding quality, microstructure and properties; finally, the possible challenges faced by magnesium alloy wire and arc additive manufacturing are summarized, providing a reference for further research and applications of magnesium alloy wire and arc additive manufacturing technology.
  • Nondestructive Testing. 2023, 45(7): 92-97.
  • Nondestructive Testing. 2023, 45(8): 89-99.
  • Zhang Kaifa, Yun Pengfei, Li Jiajia, Liu Hua, Yi Ke, Wang Chaonan, Li Wei
    Special Casting & Nonferrous Alloys. 2023, 43(9): 1291-1296.
    Fe distribution and macrostructure of SP700 ingot melted by vacuum arc remelting under different processes were analyzed comparatively. The results indicate that Fe in the titanium alloy presents an obvious positive segregation trend. Fe content in the core of the ingot riser is 2.38%, and cross-section range is 0.58%, while that in the core of the ingot bottom is 1.90%, and the cross-section range is 0.23%. Fe content is increased along the solidification direction and aggregate in the core and head of the ingot. The uniformity of Fe element in the electrode block is improved by adjusting the process route and selecting the appropriate intermediate alloy and distribution method. Meanwhile, Fe segregation is effectively inhibited by taking melting parameters such as strong cooling boundary, 1 000 melting current, strong stirring intensity, and long feeding time. After optimization, the composition distribution of the ingot is more uniform, and Fe content in the center of the riser is 2.03% with cross-section range of 0.21%. The grain size is reduced with homogeneous structure, and Fe segregation in the equiaxed crystal region is weakened.
  • Yin Shengming, Xia Yongzhong, Zhou Yaju, Zhao Mi, Yan Youwei
    Special Casting & Nonferrous Alloys. 2023, 43(9): 1153-1161.
    Reduced-activation ferritic/martensitic(RAFM) steel thin-wall parts with Cr content of 9% were fabricated by wire and arc additive manufacturing (WAAM). Specimens with different Ti contents (xTi-RAFM, x=0, 0.3, 0.8, mass fraction, %) were prepared by adjusting the chemical compositions of flux cored wires. The effects of microalloying Ti on the microstructure, tensile properties and oxidation resistance of xTi-RAFM steels were investigated by XRD, optical microscope, scanning electron microscope, electron probe microscope, microhardness tester and universal testing machine. The results indicate that appropriate amount of microalloying Ti(x=0.3) leads to the in-situ formation of TiC and TiO2 particles in the molten pool, which can refine grains and promote formation of martensitic microstructure. With the Ti content increasing to x=0.8, coarse ferrite grains are generated in the microstructure. When x=0.3, microhardness and tensile strength of specimens are significantly enhanced, which exhibit isotropy along different directions. In addition, the oxidation resistance of specimens is obviously improved since Ti dissolved in the matrix promoting the formation of dense oxide film during oxidation. However, with Ti content increasing to 0.8%, severe internal oxidation results in the reduction of antioxidant properties.
  • LIU Jianhua, XIA Huanxiong, GONG Hao, LIU Shaoli, ZHUANG Cunbo, AO Xiaohui
    Journal of Mechanical Engineering. 2023, 59(20): 436-450.
    As human science and technology continue to challenge extremely high precision and bad working conditions, high-end equipment has an increasingly urgent need for ultimate precision and performance. However, traditional assembly theories based on geometric quantity control fall short in addressing the issues of high-precision assembly and maintaining performance under complex working conditions. In response to the above problems, the essential features of precision assembly are first analyzed, and its state-of-the-art is then reviewed. Subsequently, a mesoscale precision-assembly theory and method are proposed, and its technical system is established. Three fundamental issues of precision assembly involving interface, cross-scale, and uncertainty and raised, and the research framework of precision assembly is presented, which covers seven aspects, including assembly joint technology, assembly accuracy analysis, assembly performance stability analysis and control, assembly uncertainty analysis and optimization, assembly process and equipment, assembly digital twin, and assembly measurement and test. Finally, an opinion that precision assembly requires analyzing the formation, evolution, and regulation mechanisms of assembly performance from multiple aspects, such as geometry, materials, assembly, and service, are pointed out, and the future development directions of integration, micro/nano, and intelligence of precision assembly are indicated.
  • ZHAO Zhibin, WANG Chenxi, ZHANG Xingwu, CHEN Xuefeng, LI Yinghong
    Journal of Mechanical Engineering. 2023, 59(19): 253-276.
    Laser powder bed fusion (LPBF) has gradually become a "potential stock" for fast, low-cost, high-performance, and short-cycle manufacturing of difficult-to-machine metal components. It is considered to be one of the most widely used metal additive manufacturing technologies, and has been widely used in aviation, aerospace and other industrial fields. However, the stability and consistency of additive manufacturing process and forming quality is a challenging problem for the industry and has become a "blocker" for LPBF to embrace the mass production. The current LPBF additive manufacturing monitoring system mainly focuses on "measuring", that is, measuring of various process information. Its quality evaluation and control technology are not mature enough, and intelligent monitoring combined with advanced sensing technology and artificial intelligence methods is expected to become a "sharp edge" for mass production of LPBF additive manufacturing. Following the trend, this paper summarizes the research progress and development status of intelligent monitoring in LPBF additive manufacturing from four aspects:LPBF defect types, process information perception, process quality intelligent evaluation, process parameter optimization and quality control. Some challenges in developing a mature intelligent monitoring system for mass production of LPBF additive manufacturing are pointed out. Finally, solutions and future prospects for addressing these challenges are discussed.
  • JIA Zhenyuan, FU Rao, WANG Fuji
    Journal of Mechanical Engineering. 2023, 59(19): 348-374.
    Carbon fiber reinforced polymer composites (CFRPs) have significant advantages in manufacturing various components of advanced equipment in the fields of aerospace, marine, energy, etc., due to their superior characteristics, including lightweight, high strength, and feasibility of integrated manufacturing to near net shape. Machining of CFRP components is one of the most critical processes for assembly and finally achieving equipment. However, CFRPs are featured with multi-phase, laminated and anisotropic nature, and the machining of CFRP components is prone to delamination and other defects, which would seriously affect their service performance and production efficiency. Therefore, high-quality and efficient machining of CFRP components has always been a hot and challenging topic for investigation. Researchers have conducted numerous academic and engineering studies from various perspectives and achieved fruitful theoretical and technical findings. This study reviewed the important research advances of machining technology for CFRP components, summarized the traditional/non-traditional machining methods and their adaptability, and elaborated the cutting theory, cutting tools, and machining process of CFRP in detail. The development history of CFRP cutting theory is first introduced at macro and micro scales, and the guidance for restraining CFRP drilling and milling defects is discussed. Then, the design concept of drilling and milling tools is analyzed in-depth, and the cutting tool developments from traditional tool geometry optimization to novel tool geometry evolution are summarized. The influencing mechanism of machining parameters, special machining trajectory, cooling process, etc., on machining quality are discussed. Finally, the future research trend of machining theory and technology has been prospected for CFRP, and the possible challenges and opportunities in new materials, unique structural characteristics, stability, and process control have been proposed.
  • Kang Jialin, Xu Jiangli, Yao Chuan'an
    Forging & Stamping Technology. 2023, 48(7): 156-161,183.
    In order to improve the fault diagnosis ability of cold rolling mill, comprehensively using the noise reduction technology of Ensemble Empirical Mode Decomposition (EEMD) algorithm and Discrete Wavelet Transformation(DWT), a joint noise reduction technology by EEMD-DWT was designed, and it was ensured that the useful features were fully preserved under the premise of removing noise.Then, the smooth curve signal was obtained by using EEMD-DWT mode for denoising, which showed excellent denoising effect.The application signal results show that when denoising with EEMD-DWT, it includes obvious impact characteristics, which effectively reduces the noise component in the region where the amplitude is near zero, and ensures that the original vibration characteristics are effectively reserved when the noise is fully removed.When DWT or EEMD method is used alone for denoising, a large amount of effective information is lost.When the EEMD-DWT joint noise reduction method is used for processing, the ideal noise reduction effect is achieved, and the useful parameters contained in the signal are fully preserved.Thus, this research can accurately identify different fault degrees of cold rolling mill, which has good theoretical support significance for improving the fault diagnosis level of similar mechanical transmission equipment.
  • ZUO Wenhao, CHEN Kuisheng, ZHAN Congchang, TU Fuquan, WU Lin
    Machine Tool & Hydraulics. 2023, 51(14): 182-187.
    For the multi-way directional valve,excessive steady-state flow power will cause the spool clamping and the operability of the directional valve to decrease.Base on AMESim and Fluent co-simulation,it is found that the peak of steady-state flow power usually occurs when the valve opening is small,tending to close the valve port;steady-state flow force accounts for 25.12% of the maximum operating force in reset process of spool valve;under the influence of steady-state flow force,the spool will obtain too large control force,which destroys the linear relationship between spool stroke and the reset spring force.Aiming at this situation,based on flow passage reconstruction method and special valve cavity method,a steady-state hydraulic power compensation method was proposed for spool valve,which was to set a kind of baffle boss on the valve core.The flow field simulation results of the improved spool show that the larger the diameter of the baffle boss is,the more obvious the effect of reducing the steady-state hydraulic force is,which can be reduced by 65.18% at most;however,too large diameter of the baffle will change the pressure characteristics of the multi-way directional valve,which makes the improvement effect not ideal.
  • Plant Maintenance Engineering. 2023, 0(14): 169-171.
  • Testing & Research
    LI Hongling, ZHANG Yanling
    Materials For Mechanical Engineering. 2023, 47(7): 37-42.
    With zinc powder and aluminum powder as raw materials and lanthanum nitrate as additive, lanthanum nitrate modified chromium-free Dacromet coating was prepared. The phase composition and micromorphology of the corrosion products of the coating after immersion in 5wt% NaCl solution were studied, and the corrosion behavior and anti-corrosion mechanism of the coating were investigated. The results show that after immersion in NaCl solution for 10 d, some zinc-rich phases in the modified coating were preferentially corroded to form Zn5(OH)8Cl2·H2O, and the surface showed a honeycomb morphology; after immersion for 30 d, the corrosion products increased and Zn5(OH)6(CO3)2 was formed, and the surface showed a sponge-like structure; after immersion for 60 d, the corrosion products gradually dissolved and peeled off, and the surface showed a three-dimensional porous network structure. The anti-corrosion mechanism of the coating included the self-repairing effect of corrosion products and rare earth passivation film, the physical shielding effect of organic silane passivation film and lamellar zinc-aluminum powder overlapping, the sacrificial anodization effect of zinc-aluminum metal, the passivation effect of rare earth and the slow-releasing effect of corrosion inhibitor.
  • LI Zhong-shan, WANG Mei, HU Yao-bo, DAI Yuan-xiao
    Transactions of Materials and Heat Treatment. 2023, 44(7): 48-56.
    The Mg-0.7Sm-0.3Zr alloy ingots with a diameter of 80 mm were extruded into bars with a diameter of 16 mm at 350, 380 and 410℃ respectively. Microstructure, texture and mechanical properties of the Mg-0.7Sm-0.3Zr alloy extruded at different temperatures were studied by means of optical microscope(OM), scanning electron microscopy(SEM), electron backscatter diffraction(EBSD) technique and room temperature tensile test. The results show that the microstructure of the as-cast alloy is mainly α-Mg matrix with coarse grain size of 20.7 μm. The grains are obviously refined after extrusion, and the average grain size is 2.83 μm after extrusion at 410℃. There are many fine grain bands alternately distributed along the extrusion direction. With the increase of extrusion temperature, the recrystallization fraction increases gradually, the strength of the alloy decreases gradually, and the elongation increases gradually. The tensile strength, yield strength and elongation of the alloy extruded at 410℃ are 202 MPa, 144 MPa and 44.4% respectively.
  • Hu Jiamin, Zhang Yunxin, Luo Jian, Li Jianjun, Yang Yunfeng, Wan Yongchao, Li Youchun, Chen Peng
    Forging & Stamping Technology. 2023, 48(8): 90-95.
    The research on hydro-pressing process for complex three-dimensional twisted hollow blade of an aero-engine was carried out, and the hydro-pressing process for hollow blade was numerically simulated by finite element analysis software. Then, the influences of length of tube blank, structure of sealing push head and hydro-forming pressure on die fittingness of tube blank, wall thickness and size during the hydro-pressing process of superalloy GH4169 thin-walled tube were investigated, and the test verification was carried out. The results show that the shorter the length of tube blank is, the easier the material at both ends of tube blank flows to the middle, and the tube blank is easy to wrinkle. The tapered sealing push head is used to effectively improve the material flow and realize the simple and effective sealing of tube blank. A small radius fillet of tube blank is formed under a relatively low hydro-forming pressure by the hydro-pressing process. When the length of tube blank is 240 mm and the hydro-forming pressure is 9 MPa, the die fittingness of tube blank is good, the minimum fillet radius is 1.0 mm and the maximum wall thickness thinning rate is 4.1%. The test results are consistent with the numerical simulation results. The formed hollow blades with good surface quality, uniform wall thickness and small thinning meet the requirements of dimensional accuracy. The purpose of short-process, low-cost and high-precision forming of complex three-dimensional twisted hollow blades is realized.
  • Feng Yutao, Hu Zhiqiang, Liu Tie, Li Guangzhi, Zhang Siyu, Wang Fengqi
    Forging & Stamping Technology. 2023, 48(8): 169-175.
    The origin, research status at home and abroad and application in the manufacturing industry of clinching technology were introduced, and the three basic forms of clinching joints and their characteristics were introduced. Then, the working principle, main working process and issues needed to be paid attention to in each working stage of clinching technology were expounded. Furthermore, by comparing with traditional riveting technology with rivets and resistance spot welding technology, their advantages in reducing process steps, reducing raw material investment, lightweight material connection, improving fatigue strength, energy conservation and emission reduction, safety and environmental protection, and reducing comprehensive cost were deeply analyzed, meanwhile, the shortcomings and future research and development directions of clinching technology in terms of sheet performance requirements, sheet layer amount requirements, sheet thickness requirements, static strength, etc. were pointed out, which provided theoretical reference and selection basis for the independent application of clinching technology in the manufacturing industry of China.
  • LI Xiaohui, HU Yuanhai, YANG Lulu, GAO Fan, WANG Wenzhen, YANG Yi, YAO Wenzhao
    Lubrication Engineering. 2023, 48(8): 196-205.
    Polyurea grease is a kind of high temperature grease with all-round properties, such as excellent oxidation stability, thermal stability, pumping property, mechanical stability, colloid stability and water resistance.The research progress of polyurea grease at home and abroad in recent years was reviewed and summarized.The effects of base oil, thickener and additives on the properties of polyurea grease such as drop point, penetration, oil separation, extreme pressure and wear resistance, were discussed.Combined with the development trend of polyurea grease, the research and development suggestions were proposed as follows.The base oil will still be dominated by mineral oil, but the consumption and proportion of polyolefin, ester oil etc.will rise.The base oil obtained from the regeneration of waste lubricating oil can also be used for the preparation of lubricating grease, and the research and development of degradable base oil should be one of the important directions in the future.The study of structure-activity relationship should be strengthened, so as to achieve the accurate design of thickener molecules that can match well with base oil and additives, thereby achieving the regulation of the comprehensive performance of polyurea.The research and development of new additives should be strengthened according to the personalized characteristics of polyurea grease.The research and development of compound polyurea metal base grease should be strengthened to give polyurea grease more excellent performance.