磁流变抛光的材料去除数学模型

对磁流变抛光液在抛光区域的固态核分布进行了理论分析。在这基础上,以Preston方程为根据,即被加工工件表面材料去除率与压力参数p成正比的关系,该压力由磁化压力和流体动压力组成,建立磁流变抛光的材料去除数学模型。在自研的试验装置上利用磁流变抛光方法加工BK7平面镜工件,验证了数学模型的合理性。     

磁流变抛光表面粗糙度建模与仿真

为研究磁流变抛光表面粗糙度与工艺参数之间的关系,本文建立数学模型并进行了求解验证。通过分析磁流变抛光技术的原理以及磁流变抛光过程中的材料去除机理,结合Preston方程建立磁流变抛光力学模型。分析工件表面受到的正压力,依据磁流变抛光机理对氧化锆陶瓷工件理论模型的流体动压力和磁场产生的磁化压力进行求解分析,具体化磁流变抛光的力学模型,解得正压力。对磁流变抛光的表面粗糙度进行建模,依据单颗磨料的材料去除作用模型建立磁流变抛光的表面粗糙度数学模型,分析抛光过程中影响表面粗糙度的具体因素,并通过MATLAB软件对方程进行仿真求解,得到磁场强度和磨料粒径对表面粗糙度的影响规律。结果表明,表面粗糙度和工件的压入深度存在一阶线性关系;当磨料粒径固定不变时,表面粗糙度随着磁场强度的增大而增大;当磁场强度固定不变时,表面粗糙度值与磨料粒径之间呈现正比关系。通过实验证明了模型和仿真结果的准确性,仿真分析得到的磁场强度与磨料粒径的关系,磁场强度与表面粗糙度之间的关系与实验一致,确定的磁场强度合理范围为0.4T左右,磨料粒径在2.5μm左右。     

基于永磁体的抗磁性材料磁流变抛光装置研究

针对现有磁流变抛光技术的加工精度难以提高,加工过程中抛光热不容易控制等问题,对磁流变抛光工艺,以及抗磁性材料工件在抛光过程中的工作间隙的磁通量密度进行了研究。对永磁体抛光刀具刀尖表面模型,以及铜合金工件表面之间的关系和模型进行了归纳,提出了一种基于永磁体的抗磁性材料磁流变抛光方法;利用Maxwell对抛光装置工作间隙磁通密度进行了仿真,并进行了相关试验。研究结果表明:基于磁流变抛光液,利用永磁体组成的抛光刀具对抗磁性材料工件进行加工,工件表面质量有了明显提高,实现了纳米级别的加工精度。     

虚拟加工的磁流变抛光面形预测

为了精确高效地预测磁流变抛光面形误差,提出一种基于虚拟加工的预测算法。针对实际抛光的特点,建立磁流变抛光面形预测的理论模型,提出面形预测质量的评价方法,并结合工程实际阐述该算法的实现方法。通过修正去除函数、重定义驻留时间和优化Preston系数等方法,得到与实际加工一致性较好的预测结果。实验表明,该方法有较高的精度、计算效率和稳定性。     

精密磁流变抛光装置的设计与应用

在介绍了磁流变抛光的基本原理基础上,对磁流变抛光的两种不同结构的装置进行了优缺点比较,从影响抛光效率和最终表面精度考虑,确定了最终的装置设计方案,给出了抛光装置的关键部件的设计,并用磁流变抛光加工了直径83mm的BK9光学平面玻璃工件,获得了Ra0.702nm的表面精度.     

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。     

圆柱型永磁体磁流变抛光头设计及其参数优化

针对传统加工技术存在表面损伤、加工效率低的问题,将极具前景的面接触式超精密磁流变抛光技术应用到3C制造业中。对圆柱型永磁体磁流变抛光头在加工过程中的抛光垫的形貌进行了研究分析,发现圆柱型永磁体磁流变抛光头在加工过程中存在一种"环状效应",利用"环状效应"对圆柱型永磁体磁流变抛光头进行了结构设计,并对其进行了设计理念分析;对圆柱型永磁体抛光头在6061的铝合金工件上进行了单因素抛光实验,通过实验获得了最优参数。研究结果表明:该圆柱型永磁体磁流变抛光头能够实现环状加工区域的高效光滑平坦化加工,工件表面粗糙度达到52 nm,材料去除率达9.1μm/min,大大提高了磁流变抛光的效率,为面形精度在微米级的超光滑平面的制造提供了一种高效的加工方法。     

磁流体辅助抛光工件表面粗糙度研究

给出了磁流体辅助抛光的机理,以及依据Preston方程建立的磁流体辅助抛光的数学模型。并通过实验详细研究了磁流体辅助抛光后工件的抛光区形状,以及抛光区内表面粗糙度情况。最终加工出了表面粗糙度为0.76 nm(rms值)的光学元件,其高频表面粗糙度达到0.471 nm(rms值),满足了对一定短波段光学研究的要求。结果表明:磁流体辅助抛光可以用于对光学元件进行超光滑加工;在磁流体辅助抛光过程中,较大粒度的磁流体抛光液有利于工件表面粗糙度快速降低,较小粒度的磁流体抛光液可以获得更加光滑的光学表面。     

曲面磁流变抛光工艺与抛光头结构分析

由磁流变抛光材料去除机理出发,阐述了磁流变抛光去除函数传递的工艺流程特点,明确抛光过程中对抛光轮与工件位置关系恒定的工艺要求。在此基础上,针对设计的磁流变抛光头结构,结合抛光轮轮廓外形与整个抛光头结构特征点计算法,对可加工曲面工件曲率半径和曲面角度范围及其影响因素进行了分析,给出了整个工艺过程中带动测头升降的气缸分别在加工位置和测量位置所需的行程及计算方法,并指出测头设计安装原则。结论可用于异形结构工具曲面加工设备的分析与设计。     

集群磁流变变间隙动压平坦化加工试验研究

为了提高光电晶片集群磁流变平坦化加工效果,提出集群磁流变变间隙动压平坦化加工方法,探究各工艺参数对加工效果的影响规律。以蓝宝石晶片为研究对象开展了集群磁流变变间隙动压平坦化加工和集群磁流变抛光对比试验,通过检测加工表面粗糙度、材料去除率,观测加工表面形貌、集群磁流变抛光垫中磁链串受动态挤压前后形态变化,研究挤压幅值、工件盘转速、挤压频率以及最小加工间隙等工艺参数对加工效果的影响规律。试验结果表明：集群磁流变平坦化加工在施加工件轴向微幅低频振动后,集群磁流变抛光垫中形成的磁链串更粗壮,不但使其沿工件的径向流动实现磨粒动态更新、促使加工界面内有效磨粒数增多,而且在工件与抛光盘之间的加工间隙产生动态抛光压力、使磨粒与加工表面划擦过程柔和微量化,形成了提高材料去除效率、降低加工表面粗糙度的机制。对于2英寸蓝宝石晶电（1英寸=2.54 cm）集群磁流变变间隙动压平坦化加工与集群磁流变抛光加工效果相比,材料去除率提高19.5%,表面粗糙度降低了42.96%,在挤压振动频率1 Hz、最小加工间隙1 mm、挤压幅值0.5 mm、工件盘转速500 r/min的工艺参数下进行抛光可获得表面粗糙度为Ra0.45 nm的超光滑表面,材料去除率达到3.28 nm/min。证明了集群磁流变变间隙动压平坦化加工方法可行有效。     

基于磁流变液的光整加工技术及其实现装置

磁流变液是一种新型的智能材料，在说明磁流变液特性的基础上，主要介绍了利用磁流变液实现零件表面光整加工的方法，重点分析了磁流变液光整加工基本原理。在此基础上，提出了实现加工的关键技术问题及解决对策，并设计了一套简易加工装置。     

磁流变抛光液流变性测试研究

磁流变抛光液在磁流变抛光中起着极其重要的作用,其性能的好坏尤其是其流变性能的好坏直接影响到磁流变抛光的成败。因此在磁流变抛光液配制的过程中需要对磁流变抛光液的流变性进行定量的测试来指导选择其组成成分和确定各成分的比例。本文根据磁流变抛光液在磁场中的流变效应设计制造了一台磁流变仪并详细分析了各部分结构和测试原理,并在此基础上用该装置对自行研制的水基磁流变抛光液试样进行了一系列的实验测量。通过对实验数据的分析,验证了该系统的可靠性并得到了一些配制磁流变抛光液的规律。     

MAGNETIC FIELD ANALYSIS AND ROUGHNESS PREDICTION IN MAGNETORHEOLOGICAL ABRASIVE HONING (MRAH)

Magnetorheological Abrasive Honing (MRAH) is a recently developed process to finish engineering surfaces. The process makes use of a magnetically stiffened abrasive-mixed magnetorheological fluid as the flexible tool and rotation-cum-reciprocation movements between the finishing medium and the workpiece surface for providing finishing action. In the present work, a finite element analysis with Mechanical/Emag module of ANSYS is performed to understand the nature of magnetic field developed in the process and verification is done with actual measurements. Considering the simulated magnetic field, a model to predict final roughness value (R _a ) is developed. The model, when applied for different work materials and various process parameters, such as magnetic flux density, process duration and workpiece rotation, yields results that are in good agreement with experimental results.     

用于薄壁件加工的磁流变夹具

磁流变液是一种新型的智能材料，可以进行固液两相的转变，而且响应速度快，在工业上有广阔的应用前景。本文讨论了磁流变液的一些性质，以及以磁流变夹具作为柔性夹具中的一种，在薄壁件加工中进行应用，并对夹紧力与铣削力进行了分析。     

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.     

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.     

Experimental investigation into tool aging effect in ball end magnetorheological finishing

The International Journal of Advanced Manufacturing Technology - Magnetorheological (MR) finishing is a smart finishing processes applied to a variety of applications. In the present work, an...     

Effect of extrusion pressure and number of finishing cycles on surface roughness in magnetorheological abrasive flow finishing (MRAFF) process

Magnetorheological abrasive flow finishing (MRAFF) was developed as a new precision finishing process for complicated geometries using smart magnetorheological polishing fluid. This process introduces determinism and in-process controllability of rheological behaviour of abrasive laden medium used for finishing intricate shapes. Magnetorheological polishing (MRP) fluid is comprised of carbonyl iron powder and silicon carbide abrasives dispersed in a viscoplastic base of grease and mineral oil and exhibits change in rheological behaviour in presence of external magnetic field. This smart behaviour of MRP fluid is utilized to precisely control finishing forces. The process performance in terms of surface roughness reduction depends on process variables like hydraulic extrusion pressure, magnetic flux density in the finishing zone, number of finishing cycles, and composition of MRP fluid. In the present work, experiments were conducted on a hydraulically powered MRAFF experimental setup to study the effect of extrusion pressure and number of finishing cycles on the change in surface roughness of stainless steel grounded workpieces. A new observation of “illusive polishing” action with the initial increase in number of finishing cycles is reported. The actual finishing action is possible only after removal of initial loosely held material remaining after grinding.     

磁流变抛光液的研究

介绍了磁流变抛光的原理和特点,并由此提出了适于抛光的磁流变液的评价标准,根据这一标准选取了磁流变液的各组分,配制出了标准的光学抛光用磁流变抛光液.通过自行研制的磁流变仪测得该磁流变液在磁场为600mT,剪切率为110rad/s时的剪切屈服应力达到70kPa.用所配磁流变液对K9玻璃进行抛光实验,试验结果表明,磁流变抛光的材料最大去除率为0.4μm/min.