Control of a Magnetorheological Transformer by Means of a Rotating Magnet Field

Russian Engineering Research - New approaches to optimizing a magnetorheological transformer are considered. The influence of a rotating magnetic field on the sedimentation of ferromagnetic...     

旋转磁场磁粒光整加工研究

为解决特大型,异型零件光整加工的难题,提出了脉冲电路控制产生旋转磁场实现磁粒光整加工的新思路。研究旋转磁场磁粒光整加工原理,并对旋转磁场发生装置进行设计分析及实验研究。结果表明,磁粒填充量直接影响材料去除量和表面粗糙度,且存在最佳值,磁粒中添加合理比例和粒度的铁粉,可以有效是提高光整加工效率,改善表面粗糙度。     

旋转永磁场光整加工中的磁场装置研究

阐述了利用永磁场和磨粒加工内孔表面的加工机理,通过改变铁芯的形状设计出了几种磁场装置,并用ANSYS对这些磁场装置进行了仿真,根据仿真结果得出了各装置的优缺点以及它们的适用范围。     

Wear and Friction Characteristics of Magnetorheological Fluid under Magnetic Field Activation

In this article, wear and friction characteristics of a magnetorheological (MR) fluid were studied under different magnetic fields. Using a pin-on-disc tribometer, the wear loss and friction coefficient were obtained with and without a magnetic field. The friction and wear of three typical materials under magnetic field were investigated at various normal loads and rotating speeds. After the wear tests, the worn surfaces of specimens were observed using a scanning electron microscope (SEM) in order to investigate the wear mechanisms, and the contacting surfaces were analyzed by energy-dispersive X-ray spectroscopy (EDS) to investigate the variation of elemental composition on the worn surface. Test results showed that the MR fluid exhibits better tribological characteristics under a magnetic field compared to the case without a magnetic field. The general morphology of the MR particles and wear debris was observed to assist with the analysis of friction and wear. The SEM micrographs and EDS spectra of the worn surfaces showed that the predominant wear mechanism in the case of the steel and brass specimens was abrasive wear by asperities and MR particles on the worn surfaces, whereas a mixed wear mechanism that included adhesive wear and abrasive wear was observed in the case of the aluminum specimen.     

波纹状磁流变制动器磁流热场强耦合分析

为研究应用于汽车的波纹状磁流变制动器在磁流热场强耦合作用下的温度特性,建立了磁流变制动器的磁流耦合和热流耦合有限元分析模型,采用直接序贯耦合法得到磁流变制动器的磁场分布和稳态非制动工况、正常制动工况、紧急制动工况、连续间歇制动工况下的温度分布及其变化规律。研究结果表明,在稳态非制动工况,磁流变制动器温度分布近乎均匀,而在正常制动、紧急制动工况和连续间歇制动工况下的最高温度分别为92. 4℃、111. 2℃、80. 4℃,制动间隙内的温度均呈现先上升后下降的变化趋势;随着励磁电流的增加,磁流变制动装置在制停过程中的最高温度也逐渐上升,但其上升幅度越来越小。研究结果可为磁流变制动器的设计和应用提供参考依据。     

基于单片机控制的电动旋转餐桌研制

简要介绍基于单片机控制的电动旋转餐桌的设计思想、创新点、电路工作原理、机械机构工作原理;主要介绍电动旋转餐桌控制系统的实现方法和基于单片机控制的电动旋转餐桌的研制过程,包括控制板和电源板硬件电路及控制软件编程设计方法。     

旋转磁场磁粒研磨管状零件内表面的工艺装置设计

为解决菅状零件内孔光整加工难题,提出了利用交流电动机定子结构产生的旋转磁场,实现磁粒光整管状零件内表面的新思路;研究了其相应加工原理,设计了磁性研磨装置,进行了工艺试验。     

A Controlled Magnetic Clamp

A clamp for establishing a thermal contact between cryostat components in a vacuum is described. The contact is established by pressing heat conductors to each other using a permanent magnet and is broken or established by applying a current pulse of the required polarity to the winding around an iron magnetic core. The device is held in the open state by a second permanent magnet. Through the pressed contacts, a copper block with a mass of ～600 g is cooled in the vacuum from the liquid-nitrogen temperature to the liquid- helium temperature within 4–5 h.     

形状记忆合金控制的圆筒式磁流变液无级传动

基于形状记忆合金热效应下的形状记忆特性和磁流变液的流变特性,介绍了形状记忆合金控制的磁流变液无级传动的工作原理;建立了能控制励磁线圈电流大小的形状记忆合金温控开关输出行程与温度、结构参数、材料参数、工作载荷等参数之间的关系式;基于Herschel-Bulkley模型描述了磁流变液剪切应力随外加磁场变化的本构方程;建立了磁流变液无级传动的传递转矩与磁场参数、材料参数、尺寸参数和运动参数之间的关系式。研究结果表明：形状记忆合金温控开关的输出行程随温度的变化而变化,磁流变液无级传动的传递转矩随外加磁场的增大而增大,输出转速能根据来自散热器气流温度的高低实现连续调整。     

Magnetic Field Scattering of a Transformer Winding on a Round Rod for a Safety Relay

Russian Engineering Research - A model permitting simulation of the magnetic field scattering of a current-bearing winding on a round ferromagnetic rod is developed. The model is verified...     

磁控等离子体弧柔性成形试验研究

为进一步提高等离子体弧柔性成形的表面质量,利用磁场控制弧柱的摆动状态进而控制单位面积上等离子体弧的热流密度,使之达到预期目的。通过磁控等离子体弧柔性弯曲成形实验,研究了等离子体弧在交变磁场中的特性,分析了加入交变磁场对板材弯曲成形表面质量、弯曲成形速度的影响规律。研究结果表明,加入适当的交变磁场可明显改善成形件的质量。     

A Computer-Controlled Magnetic Resonance Spectrometer with a Pulsed Magnetic Field

An automatic magnetic resonance spectrometer with a pulsed magnetic field is described. It has the following characteristics: a field range of 0–100 kOe, a frequency band of 25–140 GHz, a temperature range of 4.2–300 K, and a pulse duration of 12.6 ms. The spectrometer is automated to the CAMAC standard using standard modules. To record a magnetic-resonance spectrum, the following procedure is applied: the resonance-absorption signal is determined by a 10-bit analog-to-digital converter, and the magnetic filed is scanned by simulating a current pulse in a discharge circuit of the solenoid using a single input parameter—the initial charge voltage of the capacitor bank. In calibration measurements performed with spherical yttrium–iron-garnet samples, the average measurement error was 0.15%.     

应用环形磁场控制的微粉砂轮制备及其磨削性能

在超精密磨削中,金刚石微粉砂轮的磨粒分布均匀性对提高磨削表面质量至关重要,为了使微粉磨粒规则排布,提出了一种采用环形磁场控制磨粒规则排布的砂轮制备方法,制备了多种金刚石微粉砂轮,使用磁场控制制备的微粉砂轮对硬质合金YG8进行了平面及非球面磨削试验。结果表明:应用环形磁场控制可使金刚石微粉砂轮的磨粒实现规则排布,极大改善砂轮加工性能,利用环形磁控方法制备的砂轮可获得最佳表面粗糙度Ra3 nm、最佳面形精度PV318 nm的光滑镜面。     

Research on the Dynamic Characteristics of a Controlled Magnetorheological Elastometer Damper

The design of a controlled damper on the basis of a magnetorheological elastomer is described. The technique of determining the dynamic characteristics of the damper, such as the stability, the time constant, and the positioning error, in an active step-by-step displacement mode is presented. A dynamic model of the automatic-control system of the controlled damper is described. The results of experimental studies of the damper start-off current, which amounted to 0.05 A, and the transient process during movement from one point to another (the error does not exceed 2 μm) are presented.     

纵向磁场对MAG焊电弧及熔滴过渡的控制作用

将纵向磁场应用于98%Ar+2%O2和80%Ar+20%CO2保护的射流过渡MAG焊,借助高速摄像手段研究外加纵向磁场对MAG焊电弧形态及运动特征的影响规律,揭示纵向磁场对MAG焊电弧的作用本质在于压缩电弧.通过分析液流束末端的液态金属的受力情况,确立纵向磁场作用下MAG焊的熔滴过渡机制.试验结果表明,外加纵向磁场使得相对"静态"的锥形MAG焊电弧转变为高速旋转的螺旋状电弧,并且随着励磁电流的增大,电弧旋转角速度加快、可见弧长缩短、电弧电场强度提高.同时外加纵向磁场的引入还能够降低焊接电流、提高熔滴过渡频率和焊丝熔化系数.外加纵向磁场对射流过渡MAG焊接过程稳定性的影响特点与所采用的保护气体的物理性质相关.     

磁场分布对多磨头磁流变抛光材料去除的影响

为研究磁场分布对材料去除的影响,设计轴向充磁异向排布、轴向充磁同向排布、径向充磁异向排布、径向充磁同向排布4种磁铁充磁和排布方式,利用有限元软件Maxwell仿真不同磁场的磁力线分布及抛光轮表面的磁感应强度分布,并采用数字特斯拉计测量实际磁感应强度。对单晶硅基片进行定点抛光试验,检测抛光斑沿抛光轮轴向的去除轮廓及峰值点的表面形貌。仿真和实际磁感应强度检测结果表明,不同磁场分布方式对抛光区的磁场分布有很大影响,磁铁轴向充磁同向排布与径向充磁异向排布时,具有较高的磁场强度和较好的多磨头效果。定点抛光试验表明,采用轴向充磁同向排布与径向充磁异向排布这两种方式时,能实现多点加工,其中轴向充磁同向排布时加工效率较高;但采用径向充磁同向排布时,由于抛光区磁感应强度较低,磁流变微磨头无法对工件进行有效地抛光。峰值点表面形貌检测结果表明,采用不同磁场分布方式时,对工件表面均是以塑性去除方式去除。研究表明,通过优化磁铁充磁和排布方式,可实现多磨头磁流变抛光的加工原理。     

连铸旋转电磁搅拌器电磁场分布数值模拟

以有限元分析法为基础,对连铸结晶器电磁搅拌过程进行了磁场数值模拟,结果表明：电磁场作用下结晶器纵向方向上低频磁场呈现两头大中间小的分布趋势,磁场的峰值出现在与搅拌器中心对应位置附近;电磁力由铸坯外表面向中心液芯处衰减;随着低频电流的增加,钢液中磁感应强度和电磁力增大,但磁感应强度和电磁力的分布不受线圈电流的影响;随着电源频率的增加,钢液中磁感应强度和电磁力减小,且磁感应强度和电磁力的分布不受电源频率的影响。     

磁流变抛光装置中的磁路和磁屏蔽设计

利用磁流变抛光（MRF）技术对光学零件进行加工是一项极具前景的超精密加工技术。在论述磁流变抛光基本原理的基础上,详细讨论了该装置设计过程中的磁路设计,使抛光区产生足够的磁场强度;同时分析和验证了磁流体循环系统中的磁屏蔽技术设计。这些方法对磁流变抛光装置的工程应用有很好的参考价值。     

磁流变弹性体阻尼器的设计及磁路分析

针对高速切削加工过程中产生振动的情况,基于剪切模式,设计了一种磁流变弹性体阻尼器,针对磁流变弹性体阻尼器的典型磁路结构,阐述了磁路设计原理,研究了磁路计算方法,并利用ANSYS软件对其磁路结构进行了分析验证。仿真结果的分析有助于优化磁路结构,使所设计的磁流变弹性体阻尼器的磁场效能得到最大的发挥。