磁力研磨加工的永磁极结构优化设计

通过分析总结磁力研磨加工机理及永磁极结构,得出磁极端面形状对空间磁场分布的影响是决定磁力研磨加工表面质量和加工效率的关键因素。利用ANSYS软件对磁极进行建模与仿真,并对比分析仿真结果中磁力线的分布和磁场强度的分布,其结果表明,去除磁极端面中心部分材料半径与端面半径之比为1∶3的材料且在磁极端面开矩形槽的深宽之比为1∶1时,加工区域产生的磁场强度值可达到0.85~1.2T,且能获得较高的磁场强度梯度。这种利用仿真软件指导磁极设计的方法,为磁极的设计改进提供了理论依据和参考方案。     

磁力研磨加工永磁极设计及仿真研究

为进一步提高磁力研磨加工的表面质量和加工效率,基于平面磁力研磨装置,采用端面中心材料去除且开矩形槽的强永磁材料作为磁极,进行磁力研磨加工。利用ANSYS对磁极不同端面形状、开槽尺寸的磁力线分布和磁场强度分布进行模拟仿真,并通过磁力研磨加工试验验证设计磁极实际加工效果。结果表明:去除中心材料的磁极磁力线分布更加密集且增大了磁极中心处的磁场强度,从而提高研磨效率;通过仿真对比发现,当磁极中心去除材料半径与底面半径之比为1:3且开矩形槽深宽之比为1:1时研磨质量最佳。     

磁极开槽情况对磁力研磨的影响

通过ANSOFT软件仿真和实验的方法,研究在磁极头表面加工出矩形槽、60°V型槽、圆环槽和分布圆孔4种不同槽型时对磁力研磨后工件表面粗糙度的影响。采用ANSOFT软件仿真磁极头表面加工出不同槽型时,工件表面的感应磁场强度分布。仿真结果表明:在磁极头表面加工出矩形槽时,工件表面感应磁场周向梯度最明显。实验结果表明,在磁极头表面加工出矩形槽时,工件表面粗糙度改善率最高为32.95%。对比不开槽和加工出矩形槽两种磁极头形式下的磁力研磨加工结果,得出采用矩形槽开槽形式时,磁力研磨的加工效率有所提升。     

磁极开槽形状和尺寸对磁场分布和磁粒光整加工能力影响的研究

通过数值模拟和实验,研究磁极不同开槽方式和开槽尺寸对加工区磁场分布、磁粒受和和加工效率的影响。结果表明,磁极表面开矩形槽比开Ｖ形槽和漏斗形槽可以得到有利的磁场分布。开矩形槽时,槽与齿宽度之比在１：１时,可以取得较高的加工效率和较低的表面粗糙度。槽与齿宽度之比太小时,磁粒运动所需的驱动力不足,但太小时,磁粒对工件的压力减小,这两种情况都不利于加工效率和加工质量的提高。     

变电压电解加工对槽侧壁锥度的改善研究

槽结构是双极板的主要结构,电解加工是槽结构的主要加工方式之一.由于杂散腐蚀等原因,电解加工槽结构存在侧壁锥度问题.采用变电压的方法,开展单槽的电解加工仿真和实验,以改善槽的侧壁锥度.以14 V为中心电压,开展线性变电压仿真和线性变电压振动电解加工实验.研究结果表明:变电压能改善槽的侧壁锥度,在10～18 V线性变电压时...     

电磁轴承磁场分析和优化设计

电磁轴承通过控制电磁力实现转子的无接触悬浮.为了更好的控制电磁力,须对电磁铁磁场分布进行研究.对八磁极电磁铁磁场进行了磁路分析和有限元方法的计算,并计算了电磁轴承的承载力,以最大承载力为目标,对气隙和磁极柱宽度进行了优化,对优化结果进行了分析,分析结果对电磁轴承设计有一定的指导作用.     

磁场对微细电火花加工Ti-6Al-4V微孔的影响

微细电火花加工作为重要的非传统加工技术广泛应用于精密制造等领域,但加工效率低和加工质量差等问题严重制约了微细电火花加工技术的发展。为了改善微细电火花加工存在的问题,将磁场与微细电火花加工相结合,在不同的电极转速条件下研究外加磁场对Ti-6Al-4V微孔加工性能、加工精度和表面质量的影响。加工性能由材料去除率和电极磨损率表征,加工精度由过切和锥度表征,根据表面粗糙度和表面形貌来评估表面质量。试验结果表明:采用磁场微细电火花复合加工方法在Ti-6Al-4V上加工微孔时,材料去除率和电极磨损率增大,过切和锥度减小,表面粗糙度降低,加工精度和表面质量均得到改善。     

基于螺旋交叉磁场的大曲率不规则弯管内表面磁研磨研究

通过改变电磁极的励磁方式和布置方式配合吸附有磁性磨料的柔性辅助磁链形成不同研磨运动轨迹,以解决大曲率不规则弯管弯折处内表面精密抛光难题。在工件内部放置由多个径向充磁磁极串联而成的柔性辅助磁链,以加强研磨区域磁感应强度,进而增强研磨压力,并光顺通过弯管弯折处,以提高弯管弯折处内表面质量。根据磨粒运动轨迹模型,提出交叉电磁极耦合研磨磁路轨迹方法,形成螺旋交叉磁场,解决大曲率弯管弯折处磁极干涉无法排布问题。针对大曲率不规则TB8钛合金弯管弯折处内表面进行抛光实验,实验结果表明:当磨粒的平均粒径为250μm时,研磨液用量为8 m L,激励电流为1 A,转速在800 r/min范围内,经过50 min的研磨,采用螺旋交叉电磁研磨后的工件表面质量明显优于旋转电磁研磨,表面粗糙度降至Ra 0. 32μm。基于螺旋交叉磁场下的柔性辅助磁链的磁粒研磨,对大曲率不规则弯管弯折处内表面质量的提高有显著作用,为复杂空间弯管内表面的光整加工提供了一种新的方法。     

磁流变阻尼器阻尼通道结构参数对响应时间的影响研究

通过ANSYS软件进行磁场仿真得出了不同磁流体通道间隙,磁极长度,磁极形状以及磁回路厚度下磁流变阻尼器磁感应强度随时间变化的曲线图。通过分析磁场仿真结果得出:随着磁流体通道间隙的增加,其响应时间呈上升趋势;随着磁极长度的增加,其响应时间减小;磁极表面有不同形状,当磁极表面形状为平面且有圆弧倒角时其响应时间最短;活塞磁场未饱和时,随着磁回路的厚度的增加其响应时间增大,当活塞磁场饱和时,磁回路的厚度对磁流变阻尼器的响应时间不会产生影响。     

一种等强度微锥结构螺栓设计及有限元分析

针对标准螺纹牙在连接中载荷分布严重不均、应力集中等问题,研究了螺栓的结构,基于弹性力学理论分析设计了一种锥度螺纹连接结构,通过Solid Works建立了标准外螺纹和微锥内螺纹(1∶50,1∶100,1∶200,1∶300,1∶400)连接的模型,并利用Abaqus分析在相同外载下不同锥度螺纹牙的载荷分布及应力情况,发现锥度为1∶400时各圈螺纹牙载荷占比最大最小之差仅为5.6%,确定了最佳锥度,从而延长了螺栓的使用寿命。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.