太钢为核电工业攻克了世界性的技术难题

太钢不锈钢钢管公司成功攻克了一项世界性技术难题,研发出全球第一支使用挤压机生产的W型钢,产品主要用于核电裂变反应堆的管道支架。为全面提高不锈钢管市场占有率和应用范围,W型钢作为AP1000第三代核电站汽轮机发电余热排出换热系统的支撑件用钢,一直是由热轧加焊接工艺最终成W型钢,一方面热轧成本较高,另一方面对厚壁材料也增大了焊接难度,且所承担的风险远远大于无缝件。     

On the effect of relative size of magnetic particles and abrasive particles in MR fluid-based finishing process

Magnetorheological fluid-based finishing (MRFF) process is widely used for fabrication of optical material such as glasses, lenses, mirrors, etc. Performance of the process is significantly affected by the properties (size, concentration, hardness, etc.) of the constituents of MR fluid. MR fluids have been prepared by varying three abrasive particles mean sizes (4 µm, 6 µm and 9 µm) with carbonyl iron particles (CIPs) having average particles size of 6 µm. Yield stress of MR fluids is measured using a rheometer. The composition of the fluid has CIPs of 25%, abrasive 10% (by volume) and rest of the base medium (liquid). The yield stress was evaluated at magnetic flux density of 0.33 Tesla. It is observed that MR fluid having the same particle size of CIPs and abrasive particles exhibits higher yield stress as compared to other combinations. The lowest yield stress is observed in case of 9 µm abrasive particles size. A set of finishing experiments is carried out to understand the effect of relative size of magnetic particles and abrasive particles on surface roughness values.     

磁流变抛光工艺参数的研究

磁流变抛光是一种新型的光学零件加工方法,它不仅可以精确控制抛光后光学零件的面型,还能得到较高的表面质量和较高的加工效率。本文在介绍磁流变抛光基本原理的基础上,重点分析了磁流变液与工件相对速度对磁流变抛光最终效果的影响规律,在一定速度大小范围内,随着相对速度的提高,抛光加工的效率也会随之提高,光学零件的表面粗糙度会随之降低,并且还提出在抛光过程中保持相对速度一致的必要性和保持相对速度一致的方法,通过实验验证了该方法的正确性。     

Magnetic field-assisted fine finishing

A field-assisted fine finishing method has been developed which utilizes the electromagnetic behaviour of a magnetic fluid. Finishing experiments indicate that the stock removal rate and the surface roughness can be controlled by varying the current to the electromagnet.     

Development of a new magnetic abrasive finishing process with renewable abrasive particles using the circulatory system

In order to improve the finishing efficiency of the Magnetic Abrasive Finishing process, we proposed a new MAF process with renewable abrasive particles using compound magnetic finishing fluid circulatory system in this paper. This new finishing process has a circulating system that uses a conveyor belt to renew the mixed abrasive particles. This not only maintains the stability of the finishing but also ensures that the processing does not need to be interrupted. In this study, we investigated the magnetic field distribution, finishing force, and finishing behavior of the processing area. Furthermore, we designed experimental device to finish the sus304 stainless steel plate, to verify the feasibility of this process and understand its characteristics through processing experiments. Moreover, the influence of important process parameters, including magnetic particles, abrasive particles, conveyor belt line speed and working gap, on the surface quality of the workpiece is studied through the experiment. The experimental results indicate that the present process can achieve stable processing of the material surface without interruption, and the surface roughness of the sus304 stainless steel plate has been improved from 273 nm to 23 nm through this process.     

对磁流变抛光技术中磁场的分析

本文对磁流变抛光(magnetorheological finishing)过程中所采用的梯度磁场,以及磁流变抛光液（MRP fluid）中的磁性颗粒在磁场中的受力情况进行了分析,进而证明了该磁场满足磁流变抛光的要求。最后以实验对其进行了验证。     

On the process and mechanics of rotary elastoabrasive finishing

Advanced finishing processes, both bonded and loose abrasive type, can be used effectively for microfinishing of internal tubular surfaces. However, generation of uniform finish without altering the geometric form is a key challenge in many of the existing methodologies. Rotary elastoabrasive finishing is proposed as a new methodology to meet similar requirements. Elastoabrasives in the form of mesoscale balls are flexible and convenient to use without any slurry/liquid medium and are capable of controlling the abrasion through an elastomeric backup. The mechanics of material removal and the effect of elastomeric medium in the proposed methodology are discussed, supplemented by systematic experimental investigation using response surface methodology. The average roughness of hardened steel tubes with initial roughness 0.160 μm was significantly reduced to 0.017 μm, after a processing time of 40 min without altering their cylindricity. The experimental setup with rotary attachment presented in this paper is demonstrated to be a flexible system for fine finishing tubular specimens, sleeves, and high aspect ratio bores, which find extensive industrial applications.     

Internal finishing process for alumina ceramic components by a magnetic field assisted finishing process

This study presents the application of a new technique, magnetic field assisted finishing, for finishing of the inner surfaces of alumina ceramic components. The experiments performed on alumina ceramic tubes examine the effects of volume of lubricant, ferrous particle size, and abrasive grain size on the finishing characteristics. The finished surface is highly dependent on the volume of lubricant, which affects the abrasive contact against the surface; on the ferrous particle size, which changes the finishing force acting on the abrasive; and on the abrasive grain size, which controls the depth of cut. By altering these conditions, this process achieves surface finishes as fine as 0.02 μm in surface roughness (R_a) and imparts minimal additional residual stress to the surface. This study also reveals the mechanism to smooth the inner surface of alumina ceramic tube and to improve the form accuracy, i.e. the roundness of inside the alumina ceramic tube.     

平面光学元件中频误差的磁流变加工控制

为了利用磁流变加工实现对大口径平面光学元件波前中频误差的控制,研究了磁流变抛光去除函数的频谱误差校正能力和磁流变加工残余误差抑制方法。首先,比较了模拟加工前后元件中频功率谱密度(PSD1)误差和元件PSD曲线的变化,分析了磁流变去除函数的可修正频谱误差范围。然后,利用均匀去除方法分析了加工深度、加工轨迹间距和去除函数尺寸等磁流变加工参数对中频PSD2误差的影响,提出了抑制中频PSD2误差的方法。最后,对一块400mm×400mm口径平面元件的频谱误差进行了磁流变加工控制实验。实验显示:3次迭代加工后,该元件的波前PV由加工前的0.6λ收敛至0.1λ,中频PSD1误差由5.57nm收敛至1.36nm,PSD2由0.95nm变化至0.88nm。结果表明:通过优化磁流变加工参数并合理选择加工策略,可实现磁流变加工对大口径平面光学元件中频误差的收敛控制。     

滚磨光整加工实验研究与分析

针对滚磨光整加工可以改变零件的表面质量的特点,重点介绍了对零件表面粗糙度、表面显微硬度及表面应力的影响,通过对实验结果的分析得出滚磨光整加工可以提高零件的综合性能.     

NANO-FINISHING OF STAINLESS-STEEL TUBES USING ROTATIONAL MAGNETORHEOLOGICAL ABRASIVE FLOW FINISHING PROCESS

A new polishing method called Rotational (R)-Magnetorheological Abrasive Flow Finishing (MRAFF) process has been proposed by rotating a magnetic field applied to the Magnetorheological polishing (MRP) medium in addition to the reciprocating motion provided by the hydraulic unit to finish internal surface of cylindrical stainless steel (non-magnetic) workpiece. By intelligently controlling these two motions uniform smooth mirror-like finished surface in the range of nm has been achieved. For parametric analysis of the process, the experiments have been planned using design of experiments technique and response surface regression analysis is performed to analyze the effects of process parameters on finishing performance. Analysis of Variance (ANOVA) is conducted and contribution of each model term affecting percent improvement in surface finish is calculated. The experimental results are discussed and optimum finishing conditions are identified from optimization study. The present study shows that rotational speed of the magnet has most significant effect on output response (percentage improvement in surface roughness, %ΔR _a ). The best surface finish obtained on stainless steel workpiece with R-MRAFF process is 16 nm.     

Differential finishing of freeform surfaces (knee joint) using R-MRAFF process and negative replica of workpiece as a fixture

It is difficult and challenging to achieve uniform nanoscale surface finish in the contact zone, particularly on freeform (or sculptured) surfaces having different curvatures at different locations. Femoral (or, Knee joint component) is one of such biomedical freeform component which has complex profile along its curvature. Surface conditions of a femoral decide the life of the implant and they play a crucial role in its functionality. The variation in surface roughness of the femoral should be minimum in the contact zone. For this purpose, a special tooling is being proposed for rotational magnetorheological abrasive flow finishing (R-MRAFF) process. A negative replica of the workpiece (knee joint) as a tool (or a fixture) is used so that the medium flow velocity in the fluid flow channel is almost constant (or minimum possible variations) along the medium flow direction. It is able to do differential finishing also along the curvature. In addition, pulsating magnetic field has been used to generate vibrations in the medium in the finishing zone so that the possibility of fresh abrasive particles interacting with the surface of femoral is high. The surface finish has been achieved ranging from 26 nm to 62 nm using the proposed finishing technique and negative replica of the workpiece (femoral) as a fixture.     

适用于力反馈的圆筒式磁流变液执行器的设计

力/触觉反馈是虚拟现实交互技术中一种重要的交互形式。磁流变液执行器是最具发展潜力的力/触觉反馈装置。提出了一种适用于手指力反馈的便携式圆筒磁流变液执行器的设计方法,导出了基于B ingham塑性模型的阻力矩公式,分析了磁流变液特性和执行器结构参数对阻力矩的影响,并通过有限元分析进行优化设计,执行器的直径为31 mm,高度为38 mm,重200 g。实验测定了阻力矩和输入电流之间的关系,并采用二次多项式拟合。输入电流为0.6 A时,执行器产生的阻力矩为255 N.mm,结果表明,该执行器产生的阻力矩足以阻止手指抓取虚拟物体。     

光学自由曲面化学磁性研磨抛光的表面粗糙度试验

针对自由曲面光学玻璃研磨抛光存在的问题,提出通过数控技术结合化学磁性研磨技术来实现自由曲面光学玻璃的研磨抛光。应用正交试验设计对化学磁性研磨试验的4个因素进行研究,最终获得各个因素对于工件表面粗糙度影响的主次顺序,并确定其最优组合为:研磨时间60min,磁感应强度0.8T,研磨间隙1.0mm,磁极转速为3000r/min。     

内圆表面磁性研磨加工的研究

通过对薄壁套筒内表面磁性研磨加工的原理分析和影响加工特性的各种加工因素的实验研究，探讨内表面的最佳磁磨工艺方法，同时表明磁性研磨加工有着十分广阔的应用前景和较主的经济效益。     

应用在线电解修整磨削和磁流变光整加工组合工艺进行碳化硅的纳米加工

利用在线电解修整镜面磨削和磁流变光整加工技术对化学气相沉积碳化硅反射镜进行纳米级精度的加工。首先进行在线电解修整磨削，使反射镜面高效率加工成形，并获得较好的形状精度和表面质量；然后利用磁流变技术进行光整加工，以减少反射镜的亚表面损伤，提高表面质量，并通过修正加工，显著提高了工件表面的形状精度。对化学气相沉积碳化硅进行了一系列的加工试验，高效率地得到Rq=2．4nm（均方根偏差）的表面粗糙度和21．2nm的形状精度，并且对在线电解修整镜面磨削与磁流变光整加工所生成的表面特性进行了分析比较。     

应用四轴联动磁流变机床加工曲面

以永磁型磁流变抛光机为基础,提出了在光栅式加工轨迹下结合四轴联动机床(不含抛光轮转动轴)和变去除函数实现磁流变抛光技术确定性加工曲面的方法。讨论了曲面上光栅式加工轨迹等面积规划原则和基于矩阵乘积运算的驻留时间求解算法。分析了磁流变四轴联动机床的机械补偿方式,同时以变去除函数模型为基础从算法上实现了机械的剩余补偿。应用以氧化铈为抛光粉的水基磁流液对口径为80mm、曲率半径为800mm的BK7材料凸球面进行了修形验证实验,一次加工(5.5min)后显示:面形误差分布峰谷值(PV)和均方根值(RMS)从117.47nm和22.78nm分别收敛到60.80nm和6.28nm。实验结果表明:结合四轴联动的低自由度机床和变去除函数算法补偿的磁流变加工工艺能够有效地实现球面及低陡度非球面等曲面的高效确定性加工,为磁流变抛光在光学制造中的应用提供了有力的支持。     

旋转磁场在微小工件磁力研磨加工中的应用

微小工件在工业产品中的应用日益增多,相对于其他工件的加工,微小工件由于在加工过程中装夹困难,至今缺少高效的加工手段。磁力研磨加工中使用旋转磁场被认为是解决微小工件加工困难的有效手段。介绍了磁力研磨技术在应用领域的最新成果,总结了产生旋转磁场几种的方法,分析了磁力研磨加工的加工原理和技术特点。讨论了影响磁力研磨加工质量的几个因素,解释了影响因素的作用原理。最后指出了在磁力研磨加工存在的问题,展望了旋转磁场在微小工件磁力研磨加工中的发展前景。     

磁流变抛光磁路的结构设计及有限元仿真

合理的磁路结构及磁场强度是决定磁流变抛光效果的关键所在。根据磁流变抛光要求设计了电磁铁磁路结构,建立了磁路结构和磁场强度分析模型。通过静态磁路理论和标量磁位分析,获得了相应磁路结构的磁场强度分布状况,并采用有限元分析软件ANSYS进行仿真,进而验证了磁路结构对磁流变抛光工艺的适应性和有效性。     

Surface roughness modeling in chemically etched polishing of Si (100) using double disk magnetic abrasive finishing

Abstract

The present paper focuses on proposing a new method for determining the surface roughness of chemically etched polishing of Si (100) using double disk magnetic abrasive finishing (DDMAF). Based on chemical etching in KOH solution Vicker’s hardness of Si (100) at different concentration of KOH was determined in context to chemical etching phenomenon. A mathematical relationship was established to relate Vicker’s hardness of Si (100) as a function of the concentration of KOH. The penetration depth of abrasive particle into Si (100) workpiece was determined considering viz; the normal force acting on the abrasive particle under the influence of magnetic flux density and Vicker’s hardness of etched Si (100). The other modeling variables such as wear constant, penetration area of the abrasive particle into Si (100) workpiece which is dependent on the penetration depth of abrasive particle was modified in terms of magnetic flux density and concentration of KOH. The process parameters such as working gap, abrasive mesh number and the rotational speed of the primary magnet were also considered in modeling the surface roughness. The results of surface roughness obtained by the model were also experimentally validated. The theoretical and experimental findings agreed well with each other.