Due to the lack of high dynamic flow measurement methods,it is difficult to directly measure the flow of pilot stage.A dynamic flowmeter with flow-displacement conversion function was designed,and the flowmeter was applied to the pilot stage of the dis-placement-flow feedback type proportional direction valve to measure and control the flow of the pilot valve,and form a proportional di-rection flow valve with pilot flow amplification.The simulation model of the proportional directional flow valve with pilot flow amplifica-tion was built in SimulationX,and the dynamic and static characteristics of the valve were studied.The results show that the valve has good static control precision and can accurately control the output flow;the larger the pressure difference between the inlet and outlet of the main valve is,the faster the dynamic response of the spool is;the load change will cause the flow overshoot,but the adjustment time is short.
At present, for the study of the dynamic characteristics of the hydro-pneumatic suspension of vehicles, the elastic force is mainly modeled by the variable gas equation of state, and the damping force is modeled by thin-walled orifice theory, which only considers the turbulent flow. Here, based on expressing the whole flow field including laminar flow, transition flow, and turbulence with piecewise function, the turbulence region is modeled by the Brasius formula and thin-walled orifice theory respectively. By applying vibration signals collected from real roads, the responses of two piecewise function damping force models and traditional thin-walled orifice model of 1/4 suspension system in the time domain and frequency domain respectively are calculated. The average absolute error MAE and root mean square error RSME are used to compare them with the real upper fulcrum data of the suspension cylinder. The results show that different models can simulate suspension vibration well in the low-frequency range, but there are obvious deficiencies in the middle and high-frequency range, while the short-hole flow theoretical model in the form of a piecewise function is closer to the real value in the frequency domain.
Aiming at the integration, transmission and sharing of multi-source heterogeneous data in the production process of textile machinery manufacturing enterprises, and combining with the actual production of enterprises, an enterprise-oriented business process model is built, a workshop manufacturing process data management model is established, and the production data is preprocessed such as anomaly correction, time registration, timing data complement, etc., and the ontology-based heterogeneous data integration method is adopted, realized the data integration and sharing of intelligent production in textile machinery manufacturing workshop, and provided data support for digital twin platform and simulation optimization decision; the digital workshop data integration management system is designed and developed. Through the integration of SAP, SCADA and other system data, the production progress tracking, equipment operation monitoring and production-related data statistical analysis are realized, and three-dimensional visualization is carried out in combination with three-dimensional models to meet the data management requirements of the workshop.
In order to improve the energy capture performance of vertical axis lift wind turbines in a low wind speed environment, the drag wind turbine is employed to couple with the design of existing vertical axis lift wind turbines. In contrast to the existing literature, in this work, a computational model is proposed that can simulate the interaction between the turbine and the fluid. The effects of pitch angle (β), installation angle (θ), overlap ratio (ε) and diameter ratio (DL) on the energy capture performance of hybrid vertical axis wind turbines are systematically analyzed based on Taguchi and CFD methods. The results show that under the optimized parameter combination, the peak energy capture coefficient of the lift-drag hybrid wind turbine can be increased to 0.2328, compared with 0.0309 and 0.0287 of the pure lift and drag turbine, respectively. In addition, the result of the prototype test show that the optimized hybrid wind turbine not only has a better-starting performance but also has 2.0 times the output power of that of the lift wind turbine.
Aiming at the problem that the flow rate of the two cavities of the differential cylinder does not match and it is not easy to achieve pump control, the team proposed the asymmetrical distribution principle of the axial piston pump with three ports, which can compensate for the flow difference between the two cavities of the differential cylinder without auxiliary components. Based on this principle, a new type of valve plate structure is designed by using the residual compression method. The pump performance is analyzed by PumpLinx simulation and experiment; the influence of the transition zone structure on the pressure and flow characteristics of the piston pump is researched. The basic characteristics of the pump such as pressure, flow, and noise under different working conditions were tested on the experimental platform, and the rationality of the new structure was verified. The new flow distribution scheme can not only compensate the flow difference of the differential cylinder, but also output two different pressures, which realizes the ideal effect of the hydraulic pump directly controlling the differential cylinder. The research work lays a theoretical foundation for the realization of the pump-controlled volumetric direct drive system.
Due to its advantages of having a high power-to-weight ratio and being energy-efficient, the electro-hydraulic servo pump control system (abbreviated as EHSPCS) is frequently employed in the industrial field, such as the electro-hydraulic servo pump control (EHSPC) servomotor for steam turbine valve regulation control. However, the EHSPCS has strong nonlinearity and time-varying features, and the factors that cause system performance degradation are complex. Once a system failure occurs, it may lead to serious accidents, causing serious casualties and economic losses. To address the above issues, a system health assessment method based on LSTM-GRNN-ANN (LGA) deep neural network is proposed in this paper. Firstly, with oil volume gas content, servo motor air-gap flux density, and system leakage coefficient as the health assessment performance indicators, a health assessment performance index system for the EHSPCS is built, Furthermore, the system performance index threshold is set. Secondly, an LGA deep neural network is constructed by combining LSTM, GRNN and ANN, and a deep neural network based on the LGA is used to create an EHSPCS health assessment model. Subsequently, system feature parameter extraction, algorithm design, and parameter debugging are carried out. Finally, an EHSPCS experimental platform is established, typical system failure simulation experiments are designed, and comparative experimental analysis is conducted. The experimental findings demonstrate that the average accuracy of the system health assessment model based on the LGA deep neural network suggested in this paper is 96.37%, compared to 89.84%, 87.99% for LSTM and GRNN, which validates the accuracy of the system health assessment model based on the LGA deep neural network.
Aiming at the problem of insufficient rigidity of the tool system and unbalanced radial force during deep hole machining, this paper designs a deep hole connector using the fluid dynamic pressure lubrication principle. The deep hole connector includes double-bridge strain gauges and tiltable tiles, which can increase the rigidity of the tool system by using the oil film support stiffness and offset the unbalanced radial force of synchronous detection by adjusting the oil film pressure in real time. First, the mathematical model of tiltable tile is established, the oil film thickness formula is derived, and the formula of oil film pressure is derived. Then, based on Fluent software, the fluid simulation of the deep hole connector is carried out. The simulation adopts a single-factor experiment method, and the change law of oil film pressure on tiltable tile is analyzed under different conditions, respectively. The results show that during deep hole machining, the oil film pressure can be adjusted by adjusting the parameters of workpiece speed, cutting fluid viscosity, tile tilt angle, and tile wrap angle, and then achieve the purpose of increasing the rigidity of the tool system and offsetting the unbalanced radial force.
Aiming at the problem that the yaw angle and pitching bearing capacity of traditional robot joints are limited in the process of motion, to improve robot yaw and pitching motion performance, a single motor driven biaxial yaw joint module with large yaw angle characteristics and a pitching joint module based on parallelogram structure and spring components with low power consumption and high bearing performance characteristics are proposed and analyzed. A typical 3-DOF robot based on the two kinds of novel modules is designed, the kinematics model is established, and the workspace of the modular robot is obtained using the Monte Carlo method. The yaw capacity of the proposed module have been verified through experiments, and the results show that the modular robot operates smoothly and the two kinds of novel modules can achieve the design requirements.
Currently, most of the inspection robots for high-voltage transmission lines, both at home and abroad, utilize a multi-cantilever rigid structure. However, the inefficiency and poor safety of these robots when it comes to crossing obstacles make them impractical. To address this issue, a magnetically actuated soft inspection robot has been developed. This robot uses the amperage force applied to the current-carrying coil in a HVDC toroidal magnetic field to efficiently and flexibly cross multiple obstacles in an inchworm-like motion. The focus of this paper is on the design and theoretical calculation of the magnetically actuated model, specifically the magnetic linear traction force and magnetic adsorption force (diastolic force), required to enable the soft robot to crawl. Through simulation and kinematic analysis, the results show that the magnetically actuated soft robot design proposed in this paper is theoretically feasible, providing a foundation for future developments in magnetically actuated soft robots.
为提高H型平台双直线电机运动控制系统的抗干扰能力和同步运动性能,提出一种基于位置环和速度环双环偏差的交叉耦合滑模同步控制方法.采用交叉耦合算法建立双直线电机偏差(跟踪误差)的耦合关系,输出同步误差,并结合滑模控制器,实现跟踪误差与同步误差的同时收敛.基于仿真实验对比分析单位置环、单速度环和位置-速度双环 3 种交叉耦合结构的滑模控制在扰动输入后的位置跟踪性能和同步控制性能.仿真结果表明:位置-速度双环控制方的电机位置跟踪性能和同步控制性能较单位置环控制方法分别提升 60.6%和 51.95%,较单速度环控制方法分别提升 85.0%和41.91%,为平台的同步性控制应用提供了参考.
针对当前第三方数控系统不直接适配轧辊磨削的问题,结合轧辊磨削的具体加工特点,设计一种能够满足轧辊磨削要求的数控系统.研究轧辊磨削所需的总体功能和轧辊磨床的结构特点,提出一种用于轧辊磨削的数控系统硬件组成方案和功能任务分层架构.在研究轧辊磨削所需各项功能特点的基础上,提出各磨削功能的具体实现方法.基于所研发的数控系统开展了轧辊磨削控制实验,测试了各项磨削功能,结果表明:该数控系统能够较好地满足轧辊磨削的各项要求.
针对目前磁流变减振器的温度场研究较少且现有技术手段无法监测到减振器内部的温度分布,考虑温度对减振器性能的影响,对温度场的分析十分必要.理论分析得到温度对减振器阻尼力及可调系数的影响;考虑到流固传热及流场的相互耦合作用,分别建立流场及流固传热数学模型.在仿真软件中对减振器进行多物理场耦合建模,分析磁流变减振器的温度变化,得到其内部磁流变液的流动状态及变化规律.通过改变活塞头冲程和参数化扫描改变其阻尼间隙,获得不同条件下的温度场、流场分布状态.
以海洋平台锚泊系统为研究对象,设计张力释放绞车的机械机构与液压系统,计算张力释放绞车关键零部件参数并选型.推导基于储缆绞车减张力释放装置液压马达转角、力矩传递函数,以及锚泊系统多台绞车协调位移-力特性,采用微分先行PID控制策略结合MATLAB仿真,分析储缆绞车对减张力释放装置液压马达转角、力矩控制的影响,多台绞车的位移-力的输出特性.仿真结果表明:储缆绞车对张力释放装置的阶跃信号转角控制、正弦信号力矩控制影响较小,但张力释放装置则极大地减少了外力对储缆绞车的冲击.不同的阶段各系泊绞车主次切换,可实现对船舶或者潜器位置控制.
非对称磁极内置式永磁同步电机可以在不降低电磁转矩的情况下有效降低齿槽转矩和转矩脉动,拓宽调速范围,电机结构可靠,制作难度低,在转矩性能要求高的场合具有广泛的应用前景.为研究非对称磁极转子磁场偏转后引起的电机电磁特性的变化,建立了新的数学分析模型,结合有限元分析方法对不同磁极结构永磁同步电机的电磁性能展开分析.仿真结果表明:非对称磁极结构可有效降低内置式永磁同步电机的转矩脉动和齿槽转矩;磁极正向偏移后在最大转矩电流比控制策略下具有更宽的恒功率区调速范围.最后,给出了非对称磁极永磁同步电机在实际工程应用时控制策略的实现方法.
针对挖掘机多路换向阀开启过程中所受稳态液动力使得操纵力过大的问题,基于ANSYS对阀芯节流槽进行热流固多物理场可视化研究,通过分析半圆形节流槽阀芯下流动状态,提出新型节流槽拓扑结构,并建立Non-Parametric Re-gression响应面模型,研究新型节流槽结构尺寸对稳态液动力与质量流率的影响.结合多目标遗传算法寻优求解,并对比分析优化前后流动状态及阀芯所受稳态液动力等.结果表明:新型节流槽结构能够降低稳态液动力,有效提高了多路阀开启过程的换向性能.
新型优质γ-TiAl基合金Ti-48Al-2Cr-2Nb具有低密度、高比强度和良好的高温力学性能,在航空航天和精密微小件制造领域拥有广泛的应用前景.为研究该材料的微铣削性能,采用直径 0.8 mm的双刃硬质合金微铣刀进行四因素五水平正交试验,研究主轴转速、进给速度、铣削深度和铣刀螺旋角对微铣削加工毛刺和粗糙度的影响.结果表明:主轴转速和铣削深度是影响顶端毛刺的重要因素,铣刀螺旋角对槽底表面粗糙度影响最为显著,其结果为γ-TiAl基合金的微尺度铣削加工提供理论依据.
在铝合金建筑型材圆锯片切削过程中,型材因受到圆锯片周期性冲击而产生振动和噪声,严重影响了加工效率以及加工质量.设计圆锯片锯切铝合金建筑型材单因素实验,研究不同进给速度下铝合金建筑型材的锯切振动特性.时域分析结果显示,振动信号会随着锯切位置的变化呈现出明显的分段特性,振动最剧烈阶段的振动加速度峰值是振动最平稳阶段的 3 倍以上,说明以横向翼板类结构为代表的典型型材结构会对振动信号产生显著影响.通过频谱分析,型材锯切振动的峰值频率与圆锯片转动频率不存在倍数关系,说明转动频率不是影响型材锯切振动的主要因素,并且振动能量会随着进给速度的提高逐渐由低频处向高频处转移.随着进给速度由 25.0 mm/s提高到 75.0 mm/s,进给方向振动加速度的峰值由 1 669.91 m/s2逐渐增大至 2 001.59 m/s2,提高了 19.86%;垂直进给方向振动加速度的峰值由 932.52 m/s2 逐渐增大至1 097.30 m/s2,提高了 17.67%.结果表明:铝合金建筑型材的各种组成结构对圆锯片锯切振动的影响远大于进给速度对其产生的影响.
针对传统金属带锯床加工过程中运行状态不稳定以及对运行状态实时监控效果差的问题,结合数字孪生技术,提出一种基于数字孪生的金属带锯床运行状态实时监控方法,构建了虚拟实体与物理实体互联的数字孪生体.首先,构建基于数字孪生五维模型的带锯床运行状态实时监控系统框架;其次,在获取锯床实际运行数据后,使用TWINCAT模拟PLC运行,通过XML文件的TCP/IP通信协议进行数据通信,完成数据的实时传输,最终将数据上传至MySQL数据库中存储;再次,开发了支持实时三维监测锯床运行状态的场景漫游功能、支持通过查询历史运行数据以再现锯床历史运行状态的历史重现功能;最后,测试验证了系统的实时性与有效性.结果表明:此系统实时性、交互性较好.
为满足航空泵高功率密度化要求,微型高压柱塞泵采用阀配流方式能够有效减少泄漏,提高容积效率.针对影响微型高压柱塞泵流量输出特性的主要因素,建立阀配流微型高压柱塞泵数学模型,通过AMESim搭建不同结构的单向阀配流模型,将球阀、锥阀、平板阀等不同形式的单向阀芯进行不同组合结构的建模及仿真试验,对微泵的余隙容积、斜盘倾角、负载压力及单向阀的弹簧刚度、阀芯质量等影响因素进行仿真分析.结果表明:在现有结构下,吸液阀和排液阀均为平板阀时是最优配流阀组合形式;微泵在变转速工况下容积效率稳定,阀芯质量对配流阀迟滞性影响较小;增大斜盘倾角及减小负载压力和余隙容积能够有效改善配流阀开启滞后角,进而提高容积效率.
以具备复杂展开轮廓外圆柱面的轴类零件为研究对象,针对复杂展开轮廓外圆柱面四轴数控加工代码生成的不稳定、耗时长及效率低的问题,研究其展开轮廓三轴代码转换四轴代码的方法.基于四轴数控机床结构及运动控制机制,分析UG软件中复杂展开轮廓外圆柱面的数控代码生成方法.研究复杂展开轮廓三轴代码的刀位坐标与四轴代码的数据转换关系,开发轴类零件外圆柱面展开轮廓的四轴代码转换软件.通过UG及所开发代码转换软件,生成轴类零件复杂展开轮廓外圆柱面的四轴数控加工代码,并于Vericut软件中仿真验证.测试结果表明:所研究方法可直接实现轴类零件复杂展开轮廓外圆柱面的四轴数控代码生成,具备稳定性与速度效率的优势.
