To address the inadequate wear resistance of martensitic stainless steel (MSS) under frequent frictional contact, a Ni-P-hBN composite coating is developed with strike nickel plating (SNP) treatment in this study. The effects of hBN concentration and SNP treatment on coating microstructure, adhesion, and tribological performance were systematically investigated. Results showed that a BN concentration of 2 g/L produced the densest microstructure, the finest grain size, and the highest fractal dimension Ds, with the hardness reaching a peak value of 581.1 HV. After SNP treatment, the hardness of Ni-P-2BN further increased to 621.6 HV, the friction coefficient decreased to 0.2992, and the wear loss was reduced by 56.17%. SNP enhanced coating-substrate adhesion by 22.14% through the formation of a dense, rough Ni interlayer, effectively suppressing delamination. The densified structure further enables controlled release of the lubricating phase and stabilizes the interface, thus sustaining low friction and minimal wear during sliding. This study highlights the synergistic role of coating density and interfacial bonding in improving tribological behavior, offering theoretical insights and process guidance for the surface modification of MSS.

In the design of mechanical product families, modular design is often adopted as it enables the designer to combine product components into modules, which by nature facilitate the processing of core or foundational part (those common to all members of the product families) and variable part of the product families. In doing so, the identification of module types (corresponding to core, variable, and others) would be a critical aspect of work for the designers. Over the past years, quite some researches have been conducted on this topic, as well as those that are inevitably relevant, such as the determination of modules, i.e. module partitioning, and the analysis of module change propagation. However, there still exist some limitations, such as inadequate consideration of interdependencies and correlation characteristics between product components, and lack of comprehensive quantitative analysis of correlation relationships and change propagation impacts, leading to inappropriate determination of the modules, thus further to incorrect identification of module types. To address these limitations, this paper studies module partitioning and module change propagation first; based on this, it proposes a methodology for module type identification that is specifically oriented to module-based product family design. Firstly, by analyzing the characteristics of the entire product life cycle, five types of correlations between components are identified, covering functional, structural, maintenance, material recycling, and user requirement correlations. A comprehensive product structure model integrating multi-dimensional correlations of components is established, and module partitioning is implemented based on the hierarchical clustering algorithm. Secondly, in view of the inevitable module changes in design and to reduce their negative impacts on design efficiency and resource utilization, this paper introduces two indicators, namely the Module Comprehensive Change Propagation Impact Degree (M-CPID) and the Module Dependency Degree (MDD), and evaluates the change propagation effect by quantifying the module change cost. Thirdly, the Module Assemblability Index (MASI) is introduced to quantify the influence of module assemblability on module type identification. Finally, the Module Variation Degree (MVD) is determined by analyzing the mapping relationship between user requirements and modules. A judgment criterion is constructed by integrating the four indicators of M-CPID, MDD, MASI, and MVD to complete the identification of module types. In the end, a case study of a bridge crane is conducted to demonstrate the applicability and effectiveness of the proposed methods.

The 3-DOF Translational Force-controlled End-effector (TFE) based on 3-P(UU)2 Parallel Mechanism (PM) and pneumoelectric actuator is developed for polishing process performed by industrial robots, in which synchronous force and motion planning is critical to enhance the polishing performance. However, conventional planning methods are mainly developed to generate the trajectory for robotic motion control. Utilizing periodic splines, a new jerk-optimal Force and Motion Synchronous Planning (FMSP) method is proposed for the 3-DOF TFE to improve the force control stability between the tool and environment. Both the kinematics of the 3-DOF translational PM and the dynamics of the hybrid serial-parallel and macro-mini robotic system are established through screw theory. By introducing septuple B-splines for motion trajectory and cubic splines for contact force with periodic boundary conditions, the jerk-optimal performance index of motion and force is employed to formulate the FMSP model in Cartesian space. Simulation and experimental results demonstrate that the high-order continuity of the active driving force, moving acceleration and jerk-optimal performance index generated by FMSP is preferable compared to the Trajectory Planning with Point-to-point Force (TPWPF) and the Force-motion Linear Interpolation (FMLI) methods. The unloaded force peaks caused by the motion impact are reduced by 21 % and 22.6 % along x and y direction, respectively. Furthermore, the peaks of the contact force between the tool and workpiece decrease by 31.5 % and 20.4 % owing to slighter systemic vibration and impact. The FMSP method for force-controlled end-effector shows great potential in robotic continuous contact operations.

The hollow slender shaft is characterized by intricate component features such as a significant depth-to-diameter ratio, variable cross-sections, and non-uniform thin walls. Uneven deformation of the hollow slender shaft during deformation results in degradation of service performance. In this study, the deformation uniformity is explored from a microscopic point of view, the numerical simulation model of dynamic recrystallization of 6061 aluminum alloy is established with the DEFORM-3D software. And grain evolution during the aluminum alloy extrusion process was theoretically analyzed using the cellular automata.

To explore and predict the fatigue performance of three-roll skew rolling (TRSR) hollow axle, a combination of experimental and numerical simulation methods was used to carry out research. First, the heat treatment of TRSR hollow axle was carried out, and the metallographic test and tensile test were carried out on its specimens. Second, the rotating bending fatigue test was carried out on the specimen, and the S–N curve was obtained by data processing. Third, combined with ABAQUS and FE-SAFE, a fatigue life prediction model was created to predict the specimen life. Fourth, the fracture analysis of the specimen was carried out to determine the fracture reason. The results show that the fatigue performance of TRSR hollow axle is better than most of the hollow axle on the market, and the fatigue life prediction model can reasonably predict the fatigue life of the specimen.

In this paper, FeCoNiCrMo high-entropy alloys (HEAs) coatings was prepared on 45 steel substrate. The effects of laser energy density on the phase structure, microstructure, tribology and electrochemical properties of the coatings were studied. The results show that the structure of the coatings phase is mainly FCC and σ, and the structure is typical dendrite. With the increase in laser energy density, crystal structure and orientation becomes more complex. At the energy density of 134.4 J∙mm−2, the coatings reaches its maximum hardness of 522HV, 2.5 times that of the 45 steel, and the minimum wear rate is 3.56 × 10−6 g·N−1·m−1. The polarization curve and EIS results show that at the energy density of 132.61 J∙mm−2, which the minimum self-corrosion current density of the coatings is 4.563 × 10−6A∙cm−2. The energy density significantly improves the comprehensive mechanical properties of HEA coatings.

Aiming at the large weight of automobile steel solid shaft, this paper innovates aluminum alloy hollow shaft. The rolling process of automobile hollow shaft was simulated by using the short process flexible precision forming process and the Finite Element Method (FEM). The variation of the shape and inner hole of the rolled piece, the roundness of the outer surface and the wall thickness during the rolling process were analyzed. The numerical results verify the feasibility of rolling aluminum alloy automobile hollow shaft by this process, and provide a theoretical basis for forming aluminum alloy automobile hollow shaft in China.

Robotic fish actuated by smart materials has attracted extensive attention and has been widely used in many applications. In this study, a robotic fish actuated by dielectric elastomer (DE) films is proposed. The tensile behaviours of DE film VHB4905 are studied, and the Ogden constitutive equation is employed to describe the stress-strain behaviour of the DE film. The fabrication processes of the robotic fish, including pre-stretching treatment of the DE films, electrode coating with carbon paste, and waterproof treatment, are illustrated in detail. The dynamic response of the fabricated DE actuators under different excitation voltages is tested based on the experimental setup. Experimental results show that the first-order natural frequencies of the obtained DE actuator in air is 4.05 Hz. Finally, the swimming performances of the proposed robotic fish at different driving levels are demonstrated, and it achieves an average swimming speed of 20.38 mm/s, with a driving voltage of 5kV at 0.8 Hz.

In order to realize the high-quality production of large-size flange nuts, a new integrated forming process of flange nut blank by three-roll skew rolling and piercing is proposed in this paper. Different from the traditional hot upsetting and forging process, this new process integrates perforation and flange forming, and the whole process goes through the perforation stage and the reducing stage. Based on Simufact.Forming 15.0, the finite element simulation model forming flange nuts by three-roll skew rolling and piercing was established, and the feasibility and forming law of flange nut blank manufactured by the new process were explored. Seven main process parameters (speed of the barrel roller, feed angle of the barrel roller, plug advance, speed of the disc roller, feed angle of the disc roller, radial feed speed of the disc roller, axial traction speed of the chuck) were selected and imported into the simulation model for single factor analysis. The influence of different process parameters on the force and energy parameters of the piercing section and the forming section was explored, and the feasibility of forming the flange nut blank by the three-roll skew rolling and piercing process was verified.

针对现有重载工业机器人缺乏力控功能而难以满足去毛刺、倒角和磨抛等连续接触式作业要求的问题,提出一种含氮气弹簧的气电直驱式3-P(UU)2型三平动力控末端执行器,采用鲁棒自适应力跟踪导纳控制算法实现操作空间中接触面法向输出力的快速跟踪,适用于工件内外侧面、孔洞和狭小结构的机器人磨抛等过程.建立机构正逆运动学与气电直驱致动器动力学模型,并设计了鲁棒自适应力跟踪导纳控制器.实验结果表明,基于鲁棒自适应力跟踪导纳控制的三平动力控末端执行器力阶跃响应的稳态误差为-4.5×10-4N,上升时间19.27ms,可实现力的快速精确跟踪;负载冲击下力的调整时间116.0ms,最大超调量57.5％,具有良好的缓冲吸振特性与鲁棒性;在平面往复运动与圆柱面连续运动工况下,力均方根误差0.143 N,冲击峰值均值0.694 N,对不同材质工具磨头的接触刚度变化与环境位移误差的适应性好,可提升工业机器人的连续接触式作业质量并拓宽其应用范围.

To optimize the wall thickness quality of three-roll skew rolling (TRSR) hollow axle, this paper explores the wall thickness quality from the perspective of forming mechanism and test design analysis. First, the finite element model of TRSR hollow axle was established based on SIMUFACT software. Second, the evolution characteristics of workpiece wall thickness under various initial wall thickness conditions were found by single factor test. Third, based on the metal flow velocity, the formation mechanism of wall thickness at different positions of the workpiece is discussed, and the causes of various wall thickness defects are found. Fourth, the wall thickness quality evaluation index was proposed and the orthogonal test was carried out. The relationship between process parameters and wall thickness quality was obtained. Fifth, a method of using irregular billets was proposed to improve wall thickness quality. The results indicate that the diversity of initial wall thickness of the workpiece can lead to two phenomena: wall thinning and wall thickening. A larger wall thickness will result in thinning of the wall thickness, while a smaller wall thickness will result in thickening of the wall thickness. The method of adjusting process parameters has limited impact on improving wall thickness quality. The method of using irregular billets can greatly improve the wall thickness quality of the hollow shaft.

为研究永磁力矩电机的温度场,考虑电机各部件比热容、导热系数、动力黏度、流体边界条件、对流换热系数的影响,建立永磁力矩电机的热阻网络模型和流固耦合模型,对永磁力矩电机进行瞬态温度场仿真分析.将基于两种模型所得的热计算结果进行对比,并建立样机温升试验平台开展温度试验.试验结果表明,两种模型的温度变化趋势与试验结果接近,偏差在5％以内,由此验证两种模型的精确度与正确性,为永磁力矩电机的温度场研究提供了方法.

The hollow axle is the key basic component of high-speed trains. How to realize its production with short process and high-quality precision plastic forming is the frontier of current research and a major problem to be solved. On the basis of analyzing the advantages and disadvantages of the existing forging process of the hollow axle, this paper expounds the principles and characteristics of multi-wedge synchrostep cross-wedge rolling (MSCWR) technology, multi-roll cross-wedge rolling (MCWR) technology, three-roll skew rolling (TRSR) technology, and tandem flexible skew rolling (TFSR) technology in detail, and discusses the feasibility and key technical problems of these technologies to form the hollow axle. It is concluded that tandem flexible skew rolling (TFSR) technology has the advantages of short process, high quality, high efficiency, energy saving, and material saving, and this technology is the development direction of precision plastic forming of the hollow axle. The research results provide technical guidance and research directions for promoting global high-speed rail development.

Abstract: This paper innovatively proposes a three-roll skew rolling process for flexible forming of hollow turbine shaft, which solves the problems of long manufacturing process and low material utilization of hollow turbine shaft, the core component of aeroengine. Simufact.Forming 14.0 (SF) numerical simulation software was used to establish the finite element model of two-pass three-roll skew rolling of the GH4169 superalloy turbine shaft. The effects of process parameters on the outer diameter error, roundness error and wall thickness uniformity of the rolled piece were investigated by single factor experiments. A five-factor three-level orthogonal test was designed to explore the optimum process parameters by ' comprehensive scoring method'. The results show that the optimal process parameters are that the first pass roll rotating speed is 40 rad/min, the first pass axial speed is 15 mm/s, the second pass roll rotating speed is 50 rad/min, the second pass axial speed is 25 mm/s, and the billet preheating temperature is 1000ºC. The axial velocity of the second pass has the greatest influence on the test results, while the rotational speed of the second pass has the least influence. Under the optimal parameter combination simulation experiment, the outer diameter error, outer roundness error and wall thickness standard deviation are 0.151 mm, 0.121 mm and 0.034 mm, respectively, which are better than the results in the orthogonal test table. The research results provide a theoretical basis for realizing flexible, economical and high-quality forming of hollow turbine shaft by three-roll skew rolling.

In this paper, an Omnidirectional Mobile Robot (OMR) based on Powed Dual-Roller Caster Wheels (PDRCW) is studied. In order to realize energy-efficient trajectory planning for the OMR, the kinematic and dynamic models of the OMR are established. As the Wind Drive Optimization (WDO) algorithm has the advantages of high robustness and strong ability to obtain global optimal solution for multi -dimensional and multi-modal non-linear problems, it is suitable for solving the trajectory planning problem of the OMR. In order to improve the computational efficiency of the traditional WDO algorithm, an improved Chaotic Tent Mapping WDO (CTWDO) algorithm is employed. The simulation results show that, the trajectory generated by CTWDO consumes less energy, which is 8.4% and 3.9% lower than PSO and WDO, respectively. The convergence time of WDO is shorter, which is 3.8% and 6.3% lower than that of PSO and WDO algorithms, respectively.

针对当前应急产品品种单一、产品闲置、缺乏专门的设计理论等问题,提出了基于SA-FBS-TRIZ理论的可变功能应急产品设计方法,以期为此类产品的设计开发提供一个可行的技术途径.其中SA是指情景分析(Scenario Analysis),FBS是指功能-行为-结构设计模型(Function-Behavior-Structure),可变功能是指应急功能与日常功能可以相互切换.首先,以保护使用者的生命及财产安全作为设计开发应急产品的出发点,对所要设计的应急产品进行情景分析,构建情景演变图,明确其主要功能的变化流程,其中的产品功能由TRIZ产品VOP(Verb-Object-Parameter)功能模型定义.其次,分析系统内功能改变的各种方法,构建可变功能应急产品的FBS设计模型,据此将功能的变化映射到结构的变化上,从而获得设计所需的FBS信息.最后,通过SAFC(Substance-Attribute-Function-Causal Result)模型分析产品的技术矛盾和物理矛盾,并通过TRIZ矛盾矩阵和发明问题解决原理进行化解,最终获得产品的设计方案.文中以公交车把手为设计对象验证该方法的可行性与有效性.

可变功能机械是一类多功能集成的机械产品,较适合于采用模块化设计方法.但是,这类产品的每个功能都有相应的私有构件与之对应,除此之外还有一定数量的共享构件,造成各功能(相应地各客户需求)间存在不同程度的耦合性,因此传统的单纯解决构件间耦合的模块划分方法存在困难.为解决这一问题,本文提出通过分阶段解耦的方法实现可变功能机械的模块划分,其中第一阶段通过引入客户需求设计结构矩阵,将与产品功能相关的客户需求先进行解耦,以此解决单一解耦方式无法解决客户需求耦合的问题;第二阶段通过引入需求结构关联矩阵与构件设计结构矩阵,根据构件内部的关联关系进行结构解耦,获得模块内部高耦合、模块之间低耦合的模块划分方案.在此基础上,通过引入模块化指数的评判标准,解决产品模块聚合度和模块间耦合度相背离的问题,实现了多种模块划分方案的选优.最后通过一个多功能电钻案例来验证这一两阶段解耦模块划分方法的可行性.

The force-controlled end-effectors for industrial robots usually face the problems of low output force, poor control accuracy, or slow dynamic response. This paper presents a pneumoelectric force-controlled end-effector (PFE) for industrial robots to perform continuous contact operations. The end-effector possesses the advantages of both the pneumatic drive having large force-mass ratio and the electric direct drive having high force control accuracy and fast dynamic response. Through dynamic modeling and analyses, a force coordination control method based on impedance control is proposed for the PFE. The pneumatic cylinder is actuated by a semi-closed loop, while the voice coil motor (VCM) is controlled through a closed loop to improve the output force, accuracy, and dynamics. Impedance controller is utilized to reduce the impact caused by the critical contact between the tool and workpiece. Simulation analyses show that the force-mass ratio has increased, while the friction influence and overshoot has been reduced. In addition, prototype experiments verify the effectiveness of force control method and demonstrate that the PFE is able to achieve good performances such as control accuracy, step response, and dynamic bandwidth. Compared with the traditional pneumatic end-effector, the force control hysteresis is almost reduced from 41.9 to 0% without apparent creeping phenomenon. The rise time of the step response also decreases from 435 to 6.5 ms, and the bandwidth reaches 47 Hz. The PFE with force coordination control shows great potential in robotic deburring, grinding, and polishing applications.

以压电陶瓷驱动器作为动力输入的快速伺服刀架具有输出力大和高频率响应的优点.压电陶瓷驱动器固有的迟滞现象严重影响了快速伺服刀架的输出定位精度.为解决此问题,通过引入归一化Bouc-Wen模型建立前馈控制补偿器,归一化Bouc-Wen模型解决了经典Bouc-Wen模型中存在的参数冗余问题.获得模型参数后,基于其逆模型搭建了前馈补偿器,并在搭建的实验平台上进行了单/双自由度轨迹跟踪性能测试.实验结果表明,对于等幅正弦波信号,经前馈控制环节补偿下快速伺服刀架的最大轨迹跟踪误差为1.18％,最大轨迹跟踪偏差为2.61％,证明该文所提出的前馈控制补偿器能提高快速伺服刀架的定位精度.

在开展车辆弯道滑行实验时发现,前轮转角大小对车辆系统停止运动时间有显著的影响,而目前有关车辆行驶阻力的相关研究主要集中在高速时车辆系统的空气阻力和低速时轮胎的滚动阻力,无法揭示前轮转角对弯道车辆行驶阻力的影响.针对这一问题,本文在对单轨车辆模型进行受力分析的基础上,引入轮胎转弯阻力,并进一步分析前轮转角对轮胎转弯阻力的影响.最后,采用由电机驱动的1:5的模型车作为实验车,开展不同前轮转角条件下模型车滑行试验.模型车顺时针和逆时针的滑行试验结果一致表明,轮胎转弯行驶阻力随前轮转角的增加而显著增大.本文为进一步研究弯道行驶车辆动力学特性提供理论基础.