磁场方向往复变化的磁力电解复合抛光头的研制

为了提高磁力电解复合抛光的效果和效率,通过分析磁力电解复合抛光机理,施加了一个和电场方向平行且能往复变化的磁场,并设计了一种新型的磁力电解复合抛光头。通过实验表明,这种抛光头能方便地安装在数控机床上,并能有效地提高磁力电解复合抛光的效果和效率。     

磁力电解复合抛光中磁场作用的分析

通过对磁力电解复合抛光中垂直、平行、往复交替的磁场对带电粒子运动轨迹的分析,发现磁场并不能显著提高带电粒子的速度,而是改善电化学的条件;另外,通过比较平行电场的磁场和垂直与电场的磁场,发现在磁力电解复合抛光中有更好的效果。     

磁力电解复合抛光中电解液的选配

磁力电解复合抛光工艺在难加工材料的精加工中被广泛使用,电解液的选配是影响该工艺的一个重要因素。文中对磁力电解复合抛光工艺中电解液的选配进行了研究,对磁力电解复合抛光中电解液的基本要求进行了分析,对常见电解液的性能进行了归纳和比较,并根据抛光过程中电解液的使用,得出了磁力电解复合抛光中电解液的选配原则。     

电解-机械-磁力便携式抛光机的研制

针对具有高硬度、高韧性、高强度和低导热性的大型平面或曲面的难加工材料的工件,应用电解—机械—磁力复合抛光工艺原理,研制了便携式抛光机。试验证明,将与工件母材机械性能无关的电解作用和柔性抛光片的机械作用,以及磁场磁力作用的相结合,提高了抛光的效率和质量,解决了不便搬运的大型难加工材料工件的就地抛光问题。     

新型复合表面抛光技术

随着生产技术的不断进步,为了提高抛光效果,出现了化学一机械抛光(Chemical-MechanicalPolishing,简称CMP)、电解一机械抛光、超声波一电解抛光、磁力一电解抛光等多种复合抛光技术.为适应现代工业对抛光技术进展的需要,对几种复合抛光方法的原理、特点以及应用范围进行了叙述和总结.     

钢珠对磁力抛光工艺影响规律的实验研究

磁力抛光机利用磁场的力量,引导磨具(磁针)做快速旋转运动而抛光工件。为了使磁力抛光机对45钢轴的抛光效果及效率更佳,从理论上分析了磁力抛光的工作原理、磁力抛光过程中磨具的运动方式和影响磁力抛光效率的因素,提出加入钢珠会提升抛光效果及效率,并对45钢轴进行磁力抛光实验。实验结果表明:加工频率、磁针长度均对抛光效果及效率有不同程度的影响;加入钢珠后,抛光效果及效率都有提升;最佳磁针与钢珠的质量混合比例为1∶3。     

脉冲磁场辅助磁性复合磨粒化学机械抛光技术及其加工试验研究

提出一种脉冲磁场辅助新型磁性复合磨粒化学机械抛光技术。该技术利用磁性聚合物微球与SiO2磨粒组成的复合磨粒抛光液,在脉冲磁场辅助作用下,实现磨粒尺寸对硬质抛光盘微观形貌依赖性小、磨粒易进入抛光区域、材料去除率较高的抛光。设计了“之”字形的对位式结构电磁铁,模拟计算表明其磁感应强度沿抛光平面分布均匀,磁性微球受到的磁力一致性好。磁性微球在抛光系统中的受力分析表明：磁性微球受磁力作用时有利于复合磨粒从近抛光区进入抛光区,以二体磨损的方式去除加工表面;磁性微球不受磁力作用时,复合磨粒随抛光液的流动而移动,避免大量聚集形成磁链。以表面粗糙度Ra=1.1μm的硬质抛光盘进行硅片抛光试验,施加不同频率和占空比的脉冲磁场前后,硅片的去除率从137nm/min提高到288nm/min,频率5Hz、占空比50%时获得最大值,硅片表面粗糙度由抛光前Ra=405nm减小到Ra=0.641nm。     

小容量电器微小触头的磁力去毛刺技术

小容量电器微小触头的磁力去毛刺工艺是在磁场的作用下、利用磁性磨料形成的的柔性磁刷,对触头相应表面产生一定的碰撞、滚压、滑擦、刻划,实现触头表面的抛光和去毛刺。采用ANSYS对磁路进行了分析和设计,对磨粒与工件进行了受力及运动分析,建立了磁力研磨试验平台,进行了相应的工艺性实验。试验结果表明,磁力研磨技术对触点的抛光作用明显,并能有效去除触头毛刺。     

磁性复合磨粒化学机械抛光技术及其加工试验研究

提出一种新型的磁性复合磨粒化学机械抛光技术。该技术利用磁性聚合物微球与SiO2磨粒组成的复合磨粒抛光液,在辅助磁场的作用下,实现了一种磨粒尺寸与硬质抛光盘微观形貌依赖性小、材料去除率较高的抛光工艺。建立直径8 mm、高度不等的稀土钕铁硼永磁体以点阵形式组合形成的4类辅助磁场。仿真计算表明,柱状下凹磁极的磁场磁力HdH/dz分布均匀,磁性微球受到的磁力一致性好。对磁性微球在抛光系统中的受力分析表明,磁性微球受到的磁力有助于复合磨粒从近抛光区域进入抛光区域,磁性复合磨粒能以二体磨损的方式划擦去除加工表面。以表面粗糙度Ra 0.5μm的硬质抛光盘进行硅片抛光试验,施加辅助磁场前后,硅片的材料去除率从66 nm/min提高到179 nm/min,硅片表面粗糙度由抛光前Ra 405.860 nm减小到Ra 0.490 nm。     

磁研法在模具曲面中的抛光机理与技术研究

针对目前模具自由曲面抛光过程的难加工问题.按照模具曲面抛光要求,结合电磁场理论,提出采取磁性的磨料,通过磁场中磁力的作用实现对模具自由曲面型腔抛光加工的新工艺.从磁力研磨的加工特点着手,对抛光工艺过程的主要参数进行分析,并对磁力研磨运动轨迹的规划和生成进行探讨,提出自由曲面磁力研磨时获取均匀表面去除的方法.     

MAGNETIC-ELASTIC BUCKLING OF A THIN CURRENT CARRYING PLATE SIMPLY SUPPORTED AT THREE EDGES

The magnetic-elasticity buckling problem of a current plate under the action of a mechanical load in a magnetic field was studied by using the Mathieu function. According to the magnetic-elasticity non-linear kinetic equation, physical equations, geometric equations, the expression for Lorenz force and the electrical dynamic equation, the magnetic-elasticity dynamic buckling equation is derived. The equation is changed into a standard form of the Mathieu equation using Galerkin＇s method. Thus, the buckling problem can be solved with a Mathieu equation. The criterion equation of the buckling problem also has been obtained by discussing the eigenvalue relation of the coefficients 2 and r/ in the Mathieu equation. As an example, a thin plate simply supported at three edges is solved here. Its magnetic-elasticity dynamic buckling equation and the relation curves of the instability state with variations in some parameters are also shown in this paper. The conclusions show that the electrical magnetic forces may be controlled by changing the parameters of the current or the magnetic field so that the aim of controlling the deformation, stress, strain and stability of the current carrying plate is achieved.     

Diagnostics of electrical components by means of their external magnetic field

The external magnetic field of idling three-phase induction motors in electrical systems is investigated in the following cases: with no faults; with a turn-to-turn short-circuit in a stator phase; with rupture of a stator phase; and with static eccentricity. The field is modeled by the finite-element method on the basis of the Laplace equations and Ansoft Maxwell v.14 software.     

电磁弹性板中的Lamb波传播特性分析

用状态空间方法将电磁弹性材料中质点运动的广义位移和应力作为状态变量，结合本构方程和平衡方程，得到质点运动的状态方程；获得状态方程的通解后，利用Lamb波存在的边界条件，求出波传播的频散曲线及模态参数。所提方法推导过程简单直观，程序编制方便。以双层电磁弹性板为对象，计算了其频散曲线及模态，结果表明，电磁弹性耦合影响电势与磁势分布，而对频散特征和弹性位移影响很小。     

Analysis of electromagnetic force in wire-EDM

This paper clarifies the mechanism of how electromagnetic force applied to the wire electrode in wire electrical discharge machining (wire-EDM) is generated. This electromagnetic force is caused not only by DC component but also by AC components of the discharge current supplied to the wire. We therefore developed and used a two-dimensional finite element method (FEM) program to analyze the electromagnetic field taking into account electromagnetic induction. Assuming that trapezoidal pulse current is supplied to the wire, distributions of the current density and magnetic flux density were analyzed and changes in the electromagnetic force applied to the wire were calculated. Wire movement when the electromagnetic force alone was applied to the wire was also calculated. The calculated wire movement agreed with the measured wire movement when pulse current actually used in WEDM was supplied to the wire, clarifying the mechanism of electromagnetic force generation.     

交流励磁三维定位系统中磁传感器设计

交流励磁定位系统可以对介入式微型医疗装置在人体内的三维位置实现非接触式遥测。在定位系统中，为了测量磁场分布范围宽、下限磁场微弱的交变磁场，本文设计开发了感应线圈式磁传感器。根据电磁感应原理，感应线圈先将交变的磁信号转换为电信号，再通过后级信号处理电路在强大的噪声背景中提取出有用的电信号，结合传感器的输入输出特性，即获得待测磁场大小。实验结果表明：磁传感器能准确测量微弱交变磁场，且具有宽测量范围、高分辨率、高稳定性和高精度的优点。磁传感器还能适用于一切非导磁环境中跨度大的交变磁场的测量，具有通用性。     

非磁性界面光波磁场量的菲涅耳公式

为分析光波入射到非磁性光学界面时磁场量H的变化,根据电场量E、H、波矢k之间的关系推导了光波在非磁性光学界面上磁场量H的s分量的反射系数rHs、透射系数tHs和p分量的反射系数rHp和透射系数tHp的表达式,即得出非磁性光学界面上磁场量H的菲涅耳公式。这些公式等价于非磁性光学界面上电场量E的菲涅耳公式。rHs等于电场量E的p分量的反射系数rEp;而rHp等于电场量E的s分量的反射系数rEs。利用rHp和rHs解释了光波在非磁性光学界面上折射和反射时出现的π位相跃变效应和布儒斯特效应等重要现象。     

Development and Analysis of the Magnetic Circuit on Double-Radial Permanent Magnet and Salient-Pole Electromagnetic Hybrid Excitation Generator for Vehicles

With the improvement of vehicles electrical equipment, the existing silicon rectification generator and permanent magnet generator cannot meet the requirement of the electric power consumption of the modern vehicles electrical equipment. It is di cult to adjust the air gap magnetic field of the permanent magnet generator. Consequently, the output voltage is not stable. The silicon rectifying generator has the problems of low e ciency and high failure rate.In order to solve these problems, a new type of hybrid excitation generator is developed in this paper. The developed hybrid excitation generator has a double-radial permanent magnet, a salient-pole electromagnetic combined rotor,and a fractional slot winding stator, where each rotor pole corresponds to 4.5 stator teeth. The equivalent magnetic circuit diagram of permanent magnet rotor and magnetic rotor is established. Magnetic field finite element analysis(FEA) software is used to conduct the modeling and simulation analysis on double-radial permanent magnet magnetic field, salient-pole electro-magnetic magnetic field and hybrid magnetic field. The magnetic flux density mold value diagram and vector diagram are obtained. The diagrams are used to verify the feasibility of this design. The designed electromagnetic coupling regulator controller can ensure the stable voltage export by changing the magnitude and direction of the excitation current to adjust the size of the air gap magnetic field. Therefore, the problem of output voltage instability in the wide speed range and wide load range of the hybrid excitation generator is solved.     

磁悬浮轴承-转子系统的机电耦合动力学模型

对磁悬浮轴承 -刚性转子系统建立了完整的机电耦合动力学模型 ,其中除了人们通常所考虑的陀螺效应外 ,着重考虑和增加了推力磁轴承对转子横向振动的耦合效应和由于轴颈倾斜所引起的径向磁轴承之间的耦合效应 ,以及控制系统的电学微分方程和传感器与磁轴承非共点安装对系统性能所带来的耦合影响。该模型可用于五自由度磁悬浮轴承 -刚性转子系统的机电耦合动力学性能研究     

RESEARCH ON A MAGNETIC FIELD IN ELECTROLYTIC LAPPING

Taking electrolytic lapping stainless steel for example, the principle of electrolytic lapping with a magnetic field is described, the movement of charged particles in the magnetic field is analyzed in tems of theory. Using a computer, the motion loci of the charged particles in the magnetic field are simulated. The theory and the experiment show that the magnetic field can accelerate the diffusion and mobility of the charged particles, accelerate the electrochemical reaction and reduce the surface roughness of the work more quickly, which improves the lapping efficiency.     

RESEARCH ON AMAGNETIC FIELD IN ELECTROLYTIC LAPPING

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