On ultrasonic assisted abrasive flow finishing of bevel gears

Finishing of bevel gears is an important requirement in many machining shop floors. Variants of abrasive flow machining (AFM) could be plausible solutions for finishing such parts with intricate geometries. In the present work, a relatively new variant of AFM called ultrasonically assisted abrasive flow machining (UAAFM) technique was employed to finish bevel gears made of EN8 steel. An analysis of the process has been presented with suitable illustrations. A finite element simulation of the behavior of the medium during finishing of bevel gears using the UAAFM process has been presented. A 3D model was constructed to simulate the flow of medium through the outer wall of the gear tooth surface using computational fluid dynamics (CFD) approach. The velocity, pressure and temperature values along the length of the workpiece were computed for both UAAFM and the conventional AFM processes. Further, the effectiveness of the process was investigated through experimental trials by conducting a comparison study between classical AFM and UAAFM. Ultrasonic frequency, extrusion pressure, processing time and the media flow rate were considered as the input variables while improvements in surface finish and material removal were considered as the monitored outputs. Results confirm that improvements in surface roughness and material removal are significantly higher than those obtained with conventional abrasive flow machining. The study further reveals that, the applied high frequency (ultrasonic) vibration to the workpiece has the maximum influence on the process responses among the variables considered.     

Modeling and simulation of cylindrical electro-chemical magnetic abrasive machining of AISI-420 magnetic steel

The objective of the present research is to simulate cylindrical electro-chemical magnetic abrasive machining (C-EMAM) process for magnetic stainless steel (AISI-420). C-EMAM is a new hybrid machining process used for high efficiency finishing of cylindrical jobs made of advanced engineering materials. The material is removed from the workpiece surface due to simultaneous effect of abrasion and electrochemical dissolution. Finite element method is used to calculate the distribution of magnetic field between the magnetic poles in which cylindrical shaped workpiece is placed. The cutting forces responsible for abrasion are calculated from the magnetic forces due to gradient of magnetic field in the working gap. The effect of electrochemical dissolution and abrasion-assisted dissolution are incorporated into the C-EMAM process model using empirical relation for average anodic current. The empirical relation is correlated with the input parameters in the present system based on experimental results. Finally a surface roughness model is developed by considering total volume of material removed with the assumption of triangular surface profile. The simulation results for material removal and surface roughness are validated using experimental results. The simulated results agree with experimental observations.     

永磁场磁力研磨TC11钛合金的实验研究

目的解决钛合金机械加工后表面质量差的难题。方法采用磁力研磨工艺对TC11钛合金进行了表面光整加工。以表面粗糙度为主要评价指标,研究了磁力研磨工艺参数对钛合金表面质量的影响,并对工艺参数进行了优化。采用优化后的工艺参数对钛合金进行了表面光整加工,研究了磁力研磨工艺对钛合金金相组织的影响。结果当加工间隙为3 mm时,研磨压力适宜,加工后工件表面粗糙度值最小。采用粒径为100目的磨粒使工件表面研磨加工后纹理更细,表面粗糙度值最低。提高主轴转速,工件表面材料去除率增加,当主轴转速为1500 r/min时,加工后工件表面粗糙度值最小。对比工件加工前后的金相组织,加工后试样表面组织晶粒变细,晶界增多,工件表面应力状态由张应力转变为压应力。结论实验确定了较优的工艺参数组合,即:加工间隙为3 mm,磨粒粒径为100目,主轴转速为1500 r/min。采用永磁场磁力研磨工艺,能够大幅降低TC11钛合金表面粗糙度,并使钛合金表面组织得到改善。     

磨粒高速流动电解机械复合光整加工方法研究

针对复杂型面金属零件的光整加工,提出磨粒高速流动电解机械复合光整加工方法:采用随电解液高速流动的微小磨粒,通过加工过程中的电化学溶解和磨粒连续微量划擦,改善工件表面质量。通过对比试验分析了复合加工、纯电解加工和纯磨粒高速流动加工等3种方法对加工效果的影响,并用单因素法加工不锈钢工件,分析不同试验因素对工件表面粗糙度的影响。结果表明:采用复合光整加工方法能有效提高光整加工效率,降低工件表面粗糙度,获得较好的加工效果;当加工电压为5 V,加工间隙为2 mm,使用粒径为75~106 μm的Al₂O₃磨粒加工5 min时,工件表面粗糙度可以达到0.17 μm。      

Ultrasonic assisted magnetic abrasive finishing of hardened AISI 52100 steel using unbonded SiC abrasives

Ultrasonic assisted magnetic abrasive finishing (UAMAF) integrates the use of ultrasonic vibrations and magnetic abrasive finishing (MAF) process to finish surfaces to nanometer order in a relatively short time. The present study emphasizes on the fabrication of UAMAF setup. Using this experimental setup, experimental studies have been carried out with respect to five important process parameters namely supply voltage, abrasive mesh number, rotation of magnet, abrasive weight percentage, and pulse on time (T_on) of ultrasonic vibrations selected based on literature available in the area of MAF process and ultrasonic generator controls. Percentage change in surface roughness (?Ra) for AISI 52100 steel workpiece has been considered as response and unbonded SiC abrasives are used in the work. The experimental results showed that the UAMAF process has better finishing potential as compared to those obtainable by using MAF process for similar processing conditions. The surface roughness value obtained by UAMAF was as low as 22 nm within 80 s on hardened AISI 52100 steel workpiece using unbonded SiC abrasives. Scanning electron microscopy and atomic force microscopy studies were carried out to feel the surface texture produced and to identify finishing mechanism.     

PVA基粘弹性磁性磨具的实验研究及加工参数优化

目的检验新研制的PVA基粘弹性磁性磨具的表面光整加工性能,掌握配比参数、加工条件等因素对加工效果的影响规律,并对加工参数进行优化以达到最佳加工效果。方法以6061铝合金管外圆表面为光整加工实验对象,通过先导实验首先确定出影响加工效果的主要因素及其参数范围,而后基于响应曲面法实验,对主轴转速、两相质量比、磨粒尺寸及加工时长等因素与工件表面粗糙度下降率(%?Ra)之间的关系进行了探究分析。结果最后通过对实验结果进行方差分析,建立了PVA基粘弹性磁性磨具加工铝合金管外表面的%?Ra预测模型,并对影响参数进行了优化设计,得到在最佳实验条件下(加工时间46 min、两相质量比1.45、主轴转速635r/min、磨粒尺寸65目),工件表面粗糙度下降率为92.5%,最低表面粗糙度为59 nm,显著改善了加工效果。结论作为一种新型光整加工介质PVA基粘弹性磁性磨具,其具有良好的自适应性及流动性,能达到较好的光整加工效果。影响%?Ra的单因素显著性从强到弱依次为:加工时长、主轴转速、磨粒尺寸、两相质量比。交互作用显著的因子为两相质量比+主轴转速、加工时长+主轴转速、两相质量比+磨粒尺寸。在主轴转速、加工时长取高水平,两相质量比取中等水平,磨粒尺寸取低或高水平时,能得到较好的表面加工效果。     

Modeling of material removal and surface roughness in abrasive flow machining process

Abrasive flow machining process provides a high level of surface finish and close tolerances with an economically acceptable rate of surface generation for a wide range of industrial components. This paper deals with the theoretical investigations into the mechanism of abrasive flow machining (AFM) process. A finite element model is developed for the flow of media during AFM and the same is used to evaluate the stresses and forces developed during the process. Theoretical analysis to estimate the material removal and surface roughness obtained during AFM is also proposed. The theoretical results are compared with the experimental data available in the literature, and they are found to agree well.     

脉冲电磁场辅助平面磁粒研磨加工试验

目的 在传统的平面磁粒研磨加工中添加脉冲辅助磁场,增大加工区域中磁感应强度和加工时磁感应强度动态变化,丰富磨料粒子在加工时的运动形式,使研磨轨迹复杂化,降低工件表面粗糙度,获得更好的工件表面形貌.方法 通过分析磨料粒子在有无辅助磁场时各自的受力情况,探究辅助磁场对磨料在加工时运动状态的影响,研究脉冲辅助磁场下磨料的运动...     

磁粒研磨加工技术的研究进展

磁粒研磨加工是一种应用广泛且高效的表面加工技术,具有加工质量高、适用范围广、柔性加工、自锐性好、易于实现自动化等优点,能够有效去除工件表面的划痕、积碳、毛刺和卷边等缺陷.首先,综述了磁粒研磨加工技术的发展与研究,包括磁粒研磨加工技术的提出与发展、数学模型分析和加工参数产生的影响,其中着重论述了加工过程中单颗磨粒的力学模型建立以及铁磁相和研磨相的配比问题,并且从磁极形状、磁极转速、加工间隙和磨料性能四个方面分析了加工参数对研磨过程的影响.然后,分类介绍了磁粒研磨加工技术应用于平面、圆柱外表面和圆柱内表面时的加工原理,并对其加工特点进行了总结.归纳了几种磁粒研磨加工技术的发展方向,包括电磁磁粒研磨加工、超声辅助磁粒研磨加工、化学辅助磁粒研磨加工和电化学辅助磁粒研磨加工,对这几种新型复合加工方法的加工原理以及所能达到的实验效果进行了介绍,并评述了其各自的加工特点.最后,提出了当今磁粒研磨加工技术研究中存在的一些缺陷,并对其未来的发展趋势进行了展望.     

Design and development of the magnetorheological abrasive flow finishing (MRAFF) process

A new precision finishing process for complex internal geometries using smart magnetorheological polishing fluid is developed. Magnetorheological abrasive flow finishing (MRAFF) process provides better control over rheological properties of abrasive laden magnetorheological finishing medium. Magnetorheological (MR) polishing fluid comprises of carbonyl iron powder and silicon carbide abrasives dispersed in the viscoplastic base of grease and mineral oil; it exhibits change in rheological behaviour in presence of external magnetic field. This smart behaviour of MR-polishing fluid is utilized to precisely control the finishing forces, hence final surface finish. A hydraulically powered experimental setup is designed to study the process characteristics and performance. The setup consists of two MR-polishing fluid cylinders, two hydraulic actuators, electromagnet, fixture and supporting frame. Experiments were conducted on stainless steel workpieces at different magnetic field strength to observe its effect on final surface finish. No measurable change in surface roughness is observed after finishing at zero magnetic field. However, for the same number of cycles the roughness reduces gradually with the increase of magnetic field. This validates the role of rheological behaviour of magnetorheological polishing fluid in performing finishing action.     

小孔径内圆表面磁性研磨加工实验研究

本文以纺织配件钢领为例，对普通内圆表面和小孔径（〈20mm）内圆表面磁性研磨加工进行了试验研究。分析了不同加工参数对被加工内圆表面粗糙度和研磨量的影响。加工小孔内圆时，采用了轴向开圆槽的研磨棒，以改善磁场中磨料流的均匀性。得出了内圆表面磁性研磨加工的优化参数为：磁感应强度B〈1．2T，加工间隙△=1mm，研磨时间t=4min，工作轴向振动频率f=10Hg。     

小孔内表面磁力研磨加工技术研究进展

磁力研磨加工是提高小孔内表面质量的一种重要光整技术,利用该技术能高效提升小孔类零部件在极端环境下的使役性能。针对小孔内表面的磁力研磨光整加工,按其发展历程对磁力研磨加工技术进行总结,归纳了磁性磨粒研磨、磁针磁力研磨、液体磁性磨具研磨、超声辅助磁力研磨和电解磁力复合研磨等加工方法的技术特点,并分析评述了其局限性。对磁力研磨加工过程中材料去除机理进行了研究,材料主要以微量切削与挤压、塑性变形磨损、腐蚀磨损、电化学磨损等方式去除,材料种类不同,去除机理也不同。其中,硬脆性材料主要以脆性断裂、塑性变形和粉末化的形式去除;塑性材料在经历滑擦阶段、耕犁阶段和材料去除阶段后主要以切屑的形式去除。此外,还对磁力研磨加工过程中的材料去除模型进行了研究,对单颗磁性磨粒材料去除模型和“磁力刷”材料去除模型进行了分析讨论。最后,对磁力研磨加工技术今后的研究发展给出了建议并进行了展望。     

基于磁力研磨加工的法兰类零件表面质量的试验研究

管道、管件或器材连接处所使用的法兰盘在加工时因其内表面会产生微裂纹、褶皱等缺陷,导致使用寿命下降。用传统的抛光工艺难以实现对法兰盘管内表面的光整加工,使用磁力研磨加工工艺却可以很好地解决这一难题。通过对XK7136C数控铣床的主轴进行改造而成的研磨试验平台,其磁极主轴在给定数控程序的走刀路径下,带动侧面开槽的磁极进行转动,从而实现磁性磨粒对法兰盘管内表面光整加工的目的。对磁研磨法加工法兰盘管内表面的原理及磁性磨粒的受力情况进行了的分析,试验结果表明:法兰盘零件弯管内表面经过研磨后,原有的表面质量明显改善,表面粗糙度的值由3.46μm降低到1.18μm,验证了磁力研磨对法兰盘管内表面的光整加工效果良好。     

Fluid flow analysis of magnetorheological abrasive flow finishing (MRAFF) process

A new precision finishing process called magnetorheological abrasive flow finishing (MRAFF), which is basically a combination of abrasive flow machining (AFM) and magnetorheological finishing (MRF), has been developed for nano-finishing of parts even with complicated geometry for a wide range of industrial applications. This paper deals with the theoretical investigations into the mechanism of MRAFF process to study the effects of various process parameters. In the present work, an attempt has been made to analyze the medium flow through the fixture by finite difference method by assuming the medium as Bingham plastic to evaluate the stresses developed during the process. A capillary viscometer has been designed and fabricated to study the effect of magnetic field on the rheological properties of the medium. Microstructure of the mixture of ferromagnetic and abrasive particles in magnetorheological polishing fluid (MRPF) has been proposed, and normal force on the abrasive particles is calculated from the applied magnetic field. A model for the prediction of material removal and surface roughness has also been presented. Theoretical results compare well with the experimental data available in the literature.     

基于神经网络遗传算法的磁粒研磨TC4材料工艺参数优化

目的利用磁粒研磨光整加工技术提高TC4材料的表面质量,使用BP神经网络建立加工工艺参数和表面粗糙度之间的关系,使用遗传算法寻找最优工艺参数组合。方法使用双级雾化快凝法制备的金刚石磁性磨料对TC4材料工件进行L9(34)正交试验,借助Matlab软件建立结构为4-12-1的BP神经网络,根据正交试验结果训练BP神经网络,探究工艺参数主轴转速n、加工间隙δ、进给速率v、磨料粒径D和表面粗糙度Ra之间的关系。使用决定系数R2评判BP神经网络训练结果,基于训练好的BP神经网络使用遗传算法对工艺参数进行全局寻优。使用计算得到的优化工艺参数进行试验,并测量工件表面粗糙度,与计算得到的表面粗糙度做对比。结果BP神经网络的预测误差在1.5%以下,通过决定系数R2优化的模型可在训练样本较少的情况下进行有效可靠的预测。遗传算法优化的结果,在主轴转速为1021.26 r/min、加工间隙为1.52 mm、进给速率为1.04 mm/min、磨料粒径为197.91μm下,获得最佳表面粗糙度,为0.0951μm。使用调整后的工艺参数,在主轴转速为1020 r/min、加工间隙为1.50 mm、进给速率为1.0 mm/min、磨料粒径为196μm下,试验得到的表面粗糙度为0.093μm,与计算得到的最佳表面粗糙度误差为2.21%。结论采用磁粒研磨光整加工技术与寻优参数结合,可以有效提高TC4材料加工后的表面质量。     

Design and development of nanofinishing process for 3D surfaces using ball end MR finishing tool

A new precision finishing process for nanofinishing of 3D surfaces using ball end MR finishing tool is developed. The newly developed finishing process is used to finish ferromagnetic as well as nonmagnetic materials of 3D shapes using specially prepared magnetorheological polishing (MRP) fluid. The existing MR finishing devices and methods are likely to incapable of finish 3D intricate surfaces such as grooves in workpiece or complex in-depth profiles in the mold due to restriction on relative movement of finishing medium and workpiece. In this newly developed finishing device, the ball end MR finishing tool is used for finishing different kinds of 3D surfaces, as there is no limitation on relative movement of finishing medium and workpiece. It can finish the work surfaces similarly as the machining of 3D surfaces by CNC ball end milling cutter and open a new era of its applications in future. The developed process may have its potential applications in aerospace, automotive and molds manufacturing industries. A computer controlled experimental setup is designed and manufactured to study the process characteristics and performance. The magnetostatic simulations were done on ferromagnetic as well as nonferromagnetic materials of 3D surfaces to observe the ball end shape of magnetic field at the tip of the MR finishing tool. The experiments were performed on flat EN31 and groove surface of copper workpieces in the developed MR finishing setup to study the effect of finishing time on final surface roughness.     

钛合金管内表面的电化学磁力研磨复合光整试验

针对热挤压成型对钛合金管的内表面会产生微裂纹、褶皱、毛刺等表面缺陷的问题,提出了一种高效率的电化学磁力研磨复合光整加工方法。设计了电化学磁力研磨复合光整加工的实验装置,分别与纯磁力研磨加工和纯电化学加工进行了光整加工试验对比,检测分析了不同工艺加工前后表面的粗糙度、微观形貌、摩擦磨损行为、表面残余应力和能量谱。结果表明:在相同的加工时间内,与单纯电化学加工和磁力研磨加工相比,电化学磁力研磨复合光整加工的表面粗糙度Ra可达到0.2μm,材料去除量和加工效率显著提高;表面显微形貌要明显优于其他两种加工方式;且加工后表面很好地维持了原有材料的化学成分和表面性质;能够使表面由拉应力转变为约–200 MPa的压应力状态,从而获得更好的表面应力状态。     

基于PSO-ELM的316L不锈钢细长管磁粒研磨内表面粗糙度预测模型

针对316L不锈钢细长管磁粒研磨加工过程中,最佳工艺参数难以选择,以及加工后对工件内表面粗糙度（Ra）的预测问题,将影响磁粒研磨316L不锈钢细长管内表面粗糙度的四个工艺参数作为输入值,内表面粗糙度作为输出值,构建粒子群（PSO）优化极限学习机（ELM）模型来预测316L不锈钢细长管内表面粗糙度,利用PSO对工艺参数进行全局寻优,获得最佳工艺参数组合,最后通过试验与预测结果进行对比。构建的PSO-ELM表面粗糙度预测模型拟合优度R2为0.984 8,绝对误差（MAE）为0.013 4,均方根误差（RMSE）为0.021 4。得到的最佳工艺参数组合为：主轴转速2 389.011r/min,进给速度3.167 mm/s,磨料粒径216.185μm,加工时间35.856 min,预测Ra为0.178μm。对工艺参数进行调整,试验得到的Ra为0.182μm,与预测值相比误差为2.24%。基于PSO-ELM方法构建316L不锈钢细长管内表面粗糙度预测模型,实现对工件内表面粗糙度的精确预测,应用粒子群方法得到最佳工艺参数组合,提高了磁粒研磨316L不锈钢细长管的加工效率。     

多通管接头磨粒流光整均匀性研究

目的 提升航空油路中多通管接头内壁磨粒流光整加工效果.方法 以三通、四通金属管接头为研究对象,针对零件的材料特性、结构特性设计相关实验,研究多通管接头管道内表面磨粒流光整工艺中加工时间及加工流道对管道内壁粗糙度、材料去除量、表面质量一致性的影响.结果 加工开始时管道表面糙度Ra下降缓慢,在60 s后粗糙度开始加速下降,...     

Investigation into magnetorheological abrasive honing (MRAH)

A scheme to finish external curved surfaces, by imparting rotation while the abrasive-mixed magnetorheological fluid (or abrasive-mixed MR fluid) is pushed up and down, is presented in this paper. Since the relative motions resemble those present in conventional honing, the proposed method is named as ‘Magnetorheological Abrasive Honing’ (MRAH). This paper outlines the design and development of magnetorheological abrasive honing setup. A DC electromagnet with cylindrical pole faces is used and measurement for magnetic flux density is done. Experiments are conducted with aluminum and austenitic stainless steel workpieces to understand the effect of magnetic field. Effect of initial roughness, workpiece rotation and process duration on finishing was investigated with ground austenitic stainless steel workpieces. It is observed that the improvement in finish is better for rougher surface and higher rotation speed of workpiece and a reduction in roughness is consistent with process duration.