Dynamic mechanical characteristics of NdFeB in electromagnetic brake

With the continuous development of artillery,the disadvantages of hydraulic recoil brakes gradually appear.At the same time,the appearance of high-performance Nd Fe B permanent magnet makes it possible to apply electromagnetic braking technology to recoil mechanism.In this paper,prototype tests of a certain artillery were carried out to verify the feasibility of the electromagnetic brake(EMB)and obtain the electromagnetic braking force.Due to the brittleness of Nd Fe B,in order to eliminate the worry about the safety of EMB,SHPB experiments of Nd Fe B were carried out.Then,based on the assumption of uniform crack distribution,the law of crack propagation and damage accumulation was described theoretically,and the damage constitutive model suitable for brittle materials was proposed by combining the Zhu-Wang-Tang(ZWT)equation.Finally,the numerical simulation model of the artillery prototype was established and through calculation,the dynamic mechanical characteristics of Nd Fe B in the prototype were analyzed.The calculation results show that the strength of Nd Fe B can meet the requirements of the use in the working process.From the perspective of damage factor,the damage value of the permanent magnet on the far right is larger,and the damage value of the inner ring gradually decreases to the outer ring.

Optimum Position of Electromagnetic Brake on Slab Caster

Three-dimensional mathematical models were developed for studying the molten steel flow and the trajectories of inclusions and bubbles in continuous casting mold with electromagnetic brake.The results show that the effect of the electromagnetic brake on the molten steel flow and the movement of inclusions and bubbles depends on the position of electromagnetic brake.While EMBR Ruler is installed at the exit of the submerged entry nozzle,the velocity of the main jet of molten steel from the nozzle can be decreased effectively,the velocity of the molten steel streams near the free surface and the narrow face is reduced obviously;Meantime more inclusions and bubbles could float up to the slag layer.

Numerical simulation of transport phenomena in continuous casting of steel plates with electromagnetic brake

The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.

Study on fluid flow in the mold with electromagnetic braking

Multiphase flow control w ith electromagnetic braking（ EMBr） is w idely used in the continuous casting of steel slabs. The basic aim of the flow control system of the process is to deliver molten steel from the ladle through the tundish,upper tundish nozzle,slide gate,and submerged entry nozzle into the mold region w ith minimal defects. This requires the optimization of turbulence levels at a meniscus to avoid both an excessively fast flow（ which creates high fluctuations of the meniscus level in addition to slag entrapment,surface nonuniformities,and surface defects） and insufficient slow flow（ w hich leads to meniscus solidification,inadequate flux infiltration,and surface defects）. In this study,a Eulerian-Lagrangian approach is used to investigate the effects of EM Br and Ar bubble injection on the surface flow velocity. The results show that high Ar injection rates can lead to an increase in surface velocity.

Melt flow,heat transfer and solidification in a flexible thin slab continuous casting mold with vertical-combined electromagnetic braking

During continuous casting of steel slabs,the application of electromagnetic braking technology(EMBr)provides an effective tool to influence solidification by controlling the pattern of melt flow in the mold.Thus,the quality of the final product can be improved considerably.A new electromagnetic braking(EMBr)method,named vertical-combined electromagnetic braking(VC-EMBr),is proposed to be applied to a flexible thin slab casting(FTSC)mold.To evaluate the beneficial effects of the VC-EMBr,the melt flow,heat transfer,and solidification processes in the FTSC mold are studied by means of numerical simulations.In detail,a Reynolds-averaged Navier–Stokes turbulence model together with an enthalpy-porosity approach was used.The numerical findings are compared with respective simulations using the traditional Ruler-EMBr.The results demonstrate that the application of the VC-EMBr contributes significantly to preventing relative slab defects.In contrast to the Ruler-EMBr,the additional vertical magnetic poles of the VC-EMBr preferentially suppress the direct impact of jet flow on the narrow face of FSTC mold and considerably diminish the level fluctuation near the meniscus region.For instance,by applying a magnetic flux density of 0.3 T,the maximum amplitude of meniscus deflection reduces by about 80%.Moreover,the braking effect of the VC-EMBr effectively improves the homogeneity of temperature distribution in the upper recirculation region and increases the solidified shell thickness along the casting direction.On this basis,the newly proposed VC-EMBr shows a beneficial effect in preventing relative slab defects for FTSC thin slab continuous casting.

基于能量回收的新型电磁摩擦制动系统研究

为了提高车辆制动安全性,设计了一种新型电磁摩擦制动系统。对传统制动系统进行结构优化,并在电子控制单元(ECU)中加入制动器的辅助控制算法,分析新型制动系统在不同工况下制动时的工作原理,推导了不同车速下制动力矩、制动盘涡流与车速和外加磁场的关系,并建立了车辆动力学模型、电磁制动器模型和车辆电源模型,基于Simulink和Maxwell平台的联合仿真结果表明:在传统制动系统的基础上,通过优化电磁制动器可以显著缩短制动距离,提升制动性能。最后,通过能量回收装置成功实现了对车辆动能的回收和再利用。

基于永磁直驱用电磁制动器的设计与研究

针对永磁直驱用电磁制动器制动力大、体积大、发热严重等问题,通过场路结合的方法,简化求解电磁吸力,运用Ansys有限元软件对电磁制动器进行场域求解分析,研究电磁制动器结构尺寸、气隙、绕组匝数、高压吸合时间、低压保持电压等参数对其性能的影响,并设计了一台220 kN的电磁制动器,通过样机的试验验证了计算和分析的正确性。

CSP结晶器EMBr的冶金效果和流场理论分析

对邯郸钢铁股份有限公司CSP结晶器EMBr冶金效果分析表明,在其它工艺条件相近的条件下,使用EMBr后,薄板坯w(T[O])比未使用EMBr的薄板坯w(T[O])降低了40%,薄板坯中大型夹杂物降低了61%;无电磁制动时,结晶器液面波动为±7 mm,使用电磁制动时,结晶器液面波动为±4 mm,薄板坯内部质量明显改善。应用CFX软件数学模拟了电磁制动及无电磁制动情况下的CSP结晶器流场,模拟结果表明结晶器弯月面钢水中心线速率降低了4倍,湍动能降低了3倍左右。电磁制动可明显提高薄板坯洁净度水平。

单电机线驱动多指柔性外骨骼机械手设计

为使外骨骼机械手的作用更加柔顺、灵活、轻量和低成本,设计了一款基于柔索传递驱动的外骨骼手,整手有10条驱动线,只采用了1台伺服电机做动力源(单驱),通过传动结构和电磁线圈的通断产生的止停作用,使单一动力源的运动输出能合理分配给5根手指的驱动线,并实时控制每根手指上的两条驱动线,生成符合要求的行程运动,缩减了外骨骼手动力装置的体积和重量,降低了生产成本。

混合励磁式电涡流制退机电磁场与阻力特性分析

电涡流制退机具有无液体泄漏、无需密封、阻力稳定的优势。与目前应用较多的永磁式电涡流制退机相比,混合励磁式电涡流制退机采用线圈替代了一部分永磁体,对阻力特性的调节效果更好。对比了混合励磁式电涡流制退机2种可能的结构形式,然后根据磁路分析与初步计算选择出具有更好阻力性能的结构。针对该结构,利用等效磁路法计算气隙磁场,采用子域模型考虑感生涡流影响,建立了求解混合励磁式电涡流制退机阻力值的等效子域模型。根据某口径火炮反后坐要求,确定了制退机的主要尺寸参数,完成了混合励磁式电涡流制退机结构参数的前期设计,并通过数值计算对解析计算结果进行了验证。接着,针对某口径火炮发射时的工况建立仿真模型,以炮膛合力曲线和复进机力的后坐行程函数曲线作为条件输入,分析强冲击载荷下混合励磁式电涡流制退机的电磁阻尼力、后坐位移和后坐速度规律。最后,分析了不同气隙宽度与内筒的电导率对电磁阻尼力的影响,结果表明气隙宽度越小电磁阻尼力越大,同时过大的内筒电导率会导致电磁阻尼力呈现“马鞍”型。本文研究可为混合励磁式电涡流制退机的工程化应用提供理论基础。

强冲击载荷下电磁阻尼器磁阻尼力影响分析

永磁式电磁阻尼器具有无接触、无污染、结构简单和可靠性高等优点,将其应用在火炮制退机上具有广阔的发展前景,但火炮在发射后产生的强冲击载荷使得电磁阻尼器的加速度最高可达1200 m/s^(2),因此在强冲击载荷下磁阻尼力的影响亟需分析。为确保电磁阻尼器能够满足火炮制退机的使用要求,引入火炮后坐运动方程得到强冲击载荷下磁阻尼力的变化规律,同时利用解析模型和有限元模型对模型进行相互映证。对电磁阻尼器在后坐过程中产生的寄生效应如端部效应、磁性饱和与涡流去磁效应等进行分析,结果表明:在后坐过程中,端部效应使得端部区域磁场强度降低,从而降低磁阻尼力;磁性饱和使得涡流区域的面积增加,导致涡流去磁效应加强,使磁阻尼力曲线产生“马鞍”型效应。通过对磁阻尼力的影响进行分析,为后续电磁阻尼器的设计和优化研究提供参考。

永磁线性涡流制动的性能分析与试验研究

为弥补电磁涡流制动系统在重量和发热方面的不足,文中设计了一种永磁式线性涡流制动装置样机,基于等效磁路法推导制动力及吸力解析公式,并用于指导设计参数初始值的选取。通过有限元仿真,对比分析了永磁涡流制动与电磁涡流制动的制动力及吸力特性。搭建永磁涡流制动试验装置,测试不同速度、不同气隙的涡流制动特性,并与解析法及有限元法的计算结果进行对比和误差分析。结果表明:在与原电磁涡流制动装置长度相同的前提下,设计的永磁涡流制动装置样机可以达到与其相当的制动力水平,且在200~400 km/h区间永磁涡流制动力更稳定,吸力更低;解析计算和有限元仿真结果均与试验曲线变化趋势一致,有限元仿真精度更高;当气隙达到70 mm时,制动力和吸力均趋于0,此缓解高度与原电磁涡流制动装置的缓解高度一致。从制动力及吸力特性的角度分析,永磁线性涡流制动适合高速列车应用。

复合磁场作用下板坯结晶器内钢液流动、传热与凝固的数值模拟

为利用板坯连铸过程中电磁搅拌技术和电磁制动技术各自的优点克服自身缺点,本文应用了结合电磁搅拌和电磁制动的分体式复合磁场并提出电磁制动的结构为单条型电磁制动,对板坯连铸结晶器流场和温度场进行控制.建立了该磁场下结晶器内钢液流动、传热、凝固耦合的三维数值模拟模型.对复合磁场给予结晶器内钢液流动及传热与凝固的影响进行了分析.结果表明:施加复合磁场后,结晶器内上、下返流流速明显减小,钢液主流股对窄面的冲击深度变小,上返流整体下移,弯月面钢液形成顺时针循环流;结晶器内整体温度分布更均匀,弯月面处温度较无磁场时基本不变;结晶器出口处凝固坯壳更为均匀,其厚度较无磁场下有所增加,钢液射流对窄面附近初生坯壳冲刷程度减小.

中低速磁浮列车电磁线性涡流制动装置控制效能研究

[目的]线性涡流制动装置是磁浮列车的关键技术之一,但该技术目前仍不够成熟。对涡流制动技术进行研究,具有非常重要的理论意义和应用价值。[方法]建立了中低速磁浮列车线性涡流制动装置的模型,推导得到总涡流制动力F的计算式。为验证所设计涡流制动装置的减速效能,研制了涡流制动实物装置,并进行了台架试验。建立了电磁涡流制动力矩控制系统模型,分别基于开环控制算法、PID(比例-积分-微分)控制算法及模糊控制算法,得到这三种控制算法的中低速磁浮列车制动力特征曲线,进而对中低速磁浮列车的电磁涡流制动效能进行了深入分析。[结果及结论]对比仿真结果和试验实测结果,列车制动力的变化趋势几乎一致,由此可认为所推导的数学模型可信度较高。开环控制算法存在明显的超调,模糊控制算法较PID控制算法表现更佳。

石油钻机风冷式电磁涡流刹车存在的问题与改进方法

石油钻机配套的风冷式电磁涡流刹车主要包括刹车本体、散热装置、整流装置等关键部件。随着深井和超深井越来越多,风冷式电磁涡流刹车因自身结构原因造成的制动能力不足问题愈发突出。在深井和超深井下钻过程中,钻具越来越长、越来越重,下钻产生的热量也越来越大,散热装置的缺陷日益凸显,一方面导致制动力矩大幅下降,另一方面可能发生定子和转子“抱死”现象,甚至烧毁励磁绕组。同时还存在可控硅整流装置不能对励磁电流进行反馈,系统运行状态监测不准确,司钻操作人员操作方式不正确等问题。针对这些问题,可以通过降低转子的热变形,降低下钻速度,改造冷却方式,将可控硅整流装置由开环控制系统升级为闭环控制系统,完善电磁刹车运行状态指示,纠正司钻操作习惯等一系列措施和方法 ,实现风冷式电磁涡流刹车在使用过程中的安全性和稳定性。

涡流制动特性试验的纵向端部效应研究

涡流制动台架试验是研究涡流制动特性的重要手段,当试验使用的磁极个数少于设计数量时,纵向端部效应对试验结果有显著影响,故应对纵向端部效应的产生机理及修正方法进行深入研究。文章设计不同磁极个数的试验方案,验证端部效应对制动力和动态吸力的影响。通过2-D有限元电磁仿真,获得涡流制动磁场、涡流密度及洛伦兹力的分布规律,分析端部效应的产生机理。计算不同速度下,各磁极产生的制动力,获得端部磁极对制动力的贡献度,进而推导出端部效应的修正公式。研究结果表明,端部效应对动态吸力的影响较小,对制动力的影响比较显著,因此只需对制动力进行修正;入端磁极的制动力与中间磁极几乎相同,出端磁极的制动力相对较小,且对制动力的贡献与速度近似线性相关;通过出端磁极贡献度函数修正制动力试验数据,修正结果与3-D有限元仿真制动力的相对误差显著减小。研究结果为涡流制动试验设计和试验数据处理提供参考,有利于掌握更准确的涡流制动特性,从而指导产品研究开发。

一种阻拦炉窑的炉门异常下降的制动装置

介绍了一种阻拦炉窑的炉门异常下降的制动装置,用于解决炉窑的炉门因意外情况失去牵引力导致炉门异常下落的问题。制动装置包括炉门阻拦结构、牵引机构和控制装置。所述的制动装置结构可靠,成本低,能有效减少设备故障造成的损失。

磁轨制动器的优化设计

介绍了磁轨制动器的结构原理和常见类型,从工艺和性能角度分析了直绕型整体式磁轨存在的问题,并提出了新型结构的优化方案,通过解析计算和有限元电磁仿真进行了验证。结果表明,优化后的磁轨制动器结构可以降低工艺难度和加工成本,提高使用寿命,并使性能提升约7.6%。

Maxwell_3D的电磁制动器线圈设计与仿真研究

文章以电压28V,制动力矩0.2N.M的牙嵌式电磁制动器为例,通过分析制动器的几何模型、漆包线的规格和匝数,基于Max‐well_3D仿真软件设计出5组线圈参数数据,经过对这5组数据进行研究、分析、比较,确定数据为线径0.18、绕制1426匝的方案,产生的吸合力最大,满足设计要求,得出一种简单、可行的电磁制动器设计方案。

高速动车组永磁涡流制动器设计及测试

以仿真设计的Halbach型永磁涡流制动器为设计模型,确定了涡流制动器的安装位置以及固定机构。基于永磁体自励磁、物理、化学特性,分析了永磁体镀层防腐工艺,设计了永磁涡流制动器磁极封装结构、组装模具,有效解决了组装过程中永磁体间吸力、斥力的影响。提出了一种动作机构,可实现制动缓解状态的正常转换,最终对设计生产的永磁涡流制动器本体样机进行静态测试,测试结果与仿真结果对比误差在3%以内,同时测试并分析了永磁涡流制动器电磁辐射的影响,确立了屏蔽材料选型依据。