固结磨料研磨K9玻璃表面粗糙度模型

表面粗糙度模型是研磨过程设计和工艺参数选择的重要依据,K9玻璃是应用最广泛的光学材料之一。建立研磨K9玻璃表面粗糙度模型有利于提高加工效率、节约生产成本。简化固结磨料研磨过程,基于研磨垫表面微结构,计算研磨过程中参与研磨的有效磨粒数和单颗磨粒切入工件深度,利用研磨过程中受力平衡,建立固结磨料研磨K9玻璃表面粗糙度模型。采用不同磨粒粒径和不同磨料浓度的固结磨料研磨垫以及不同压力研磨K9玻璃验证表面粗糙度模型。结果表明：固结磨料研磨K9玻璃的表面粗糙度与磨粒粒径、研磨压力1/3次方成正比,与研磨垫浓度2/9次方成反比。表面粗糙度理论值与试验值随研磨压力、磨粒粒径和研磨垫浓度的变化趋势吻合。利用该模型能够成功预测固结磨料研磨K9玻璃表面粗糙度,指导研磨过程设计及加工过程中研磨垫和工艺参数的选择,可靠性高。     

陶瓷圆柱滚子超精研磨工艺试验

针对传统磨具很难对陶瓷圆柱滚子进行光滑无损伤表面加工的问题,提出了使用纳米多晶金刚石磨具对圆柱滚子进行研磨,为提高磨具中磨粒的分散性,采用聚丙烯腈凝胶法制备纳米多晶金刚石磨具,研究不同磨具砂结比、研磨压力、研磨速度条件下对圆柱滚子表面粗糙度和材料去除率的影响,并与酚醛热压磨具进行对比。试验结果表明:凝胶磨具中纳米金刚石分布均匀,没有出现明显的团聚现象。当砂结比为10、驱动辊转速为300r/min、研磨压力为0.5 MPa时,对陶瓷圆柱滚子研磨30 min,表面粗糙度Ra的值从0.32μm降到0.07μm。     

安全阀阀瓣研磨修复运动轨迹的研究

研磨轨迹与工件表面形貌特征密切相关,为了找出影响工件研磨轨迹的因素,建立磨粒运动数学模型,采用Matlab研究磨具中影响研磨轨迹的因素,得出偏心距e、转速比k及起始位置A对磨粒轨迹的形态变化具有不同程度的影响,这为工艺参数优选提供一定的理论基础。     

抛物面研磨的材料去除率及表面粗糙度研究

固着磨料抛物面研磨是一种新型的抛物面加工方法,文中从单个磨粒的角度出发,讨论了研磨工艺参数对材料去除率和表面粗糙度的影响,建立了理论预测模型,然后利用计算机辅助软件对不同硬度工件材料的材料去除率和表面粗糙度进行了数值模拟仿真,最后用实验验证了模型的正确性,并得出结论:理论预测模型仅能预测材料去除率和表面粗糙度的变化趋势,并不能代替实验得出具体的实验数值,即固着磨料抛物面研磨的材料去除率与主轴转速、研磨压力的5/4次方成正比,与磨粒浓度的1/4次方成反比;表面粗糙度随磨粒尺寸和研磨压力的增加而增加,随磨粒浓度的增加而减小。     

固结磨料研磨铝合金工艺研究

通过建立单粒磨料切削铝合金的受力模型,利用研磨过程中工件的受力平衡,计算单粒磨料切入工件的深度,从而建立粗糙度数学模型。并以该模型为基础,利用Matlab软件进行参数分析,讨论磨粒大小、研磨压力和磨粒浓度对表面粗糙度的影响,并进行了实验验证。结果表明:该模型准确预测了最后的表面粗糙度,为研磨铝合金工件提供了重要参考依据。     

不锈钢半固着磨具加工的工艺研究

为获得SUS440不锈钢的低／无损伤加工表面,实现高效加工,本文采用了一种半固着磨具。该磨具能够有效地阻止加工过程中大颗粒磨料对工件表面造成的异常深划痕,实现效率与加工质量平衡。本文使用了800。碳化硅磨料的半固着磨具对SUS440不锈钢进行研磨试验,研究了不同的加工参数对工件表面粗糙度和材料去除率的影响。试验结果显示在27kPa压力、60r／min转速下加工12min后,工件表面粗糙度Rn从250nm下降到50nm,材料去除率保持在1μm／min,实现了高精、高效的加工性能。     

钛合金薄壁曲面液态金属-磨粒流加工仿真与试验研究

针对钛合金薄壁曲面工件磨粒流抛光后表面粗糙度分布不均匀的问题,提出一种基于液态金属的磨粒流加工方法。基于SST k-ω模型、OKA冲蚀模型,流体流动颗粒追踪模型,采用COMSOL有限元软件对不同电场布置下的液态金属-磨粒流动力学特性开展深入研究。仿真结果表明,通过电场的合理布置可以控制液态金属颗粒在流场中运动;合理的电场布置可以有效提高工件表面加工均匀性,并通过仿真得出了一组冲蚀较好的试验参数。基于仿真结果开展了液态金属-磨粒流加工试验,试验结果表明：液态金属-磨粒流加工方法可有效提高工件表面加工的均匀性。在加工14 h后,不加电场的磨粒流加工表面不同区域的粗糙度分布不均,工件凹陷处粗糙度明显大于凸起处,各区域表面粗糙度极差达到66.1 nm。使用液态金属-磨粒流加工后的工件表面各区域粗糙度的均匀性明显提高,各区域表面粗糙度极差减小为20.3 nm,为液态金属-磨粒流加工的开展及其调控提供了理论和试验依据。     

不同磨具在电泳磨削中的应用

本文介绍了基于超微磨粒电泳效应的磨削加工机理，着重分析不同材料特性的磨具对电泳磨削效果的影响。通过对半导体硅片的电泳磨削试验，表明弹性模量小的磨具能更有效地降低工件表面粗糙度。     

砂带磨削加工表面粗糙度预测与验证

为了研究砂带磨削过程中主要工艺参数对磨削表面粗糙度的影响规律,建立了砂带磨削工件的表面轮廓模型,通过对砂带磨粒运动轨迹的研究分析,由单个磨粒的运动方程建立多个磨粒的运动方程。采用单因素试验法,由仿真软件合成磨削加工表面的三维形貌与粗糙度值的变化趋势,通过建立表面粗糙度回归数学模型与叶片磨削试验进行理论分析验证。结果表明,不同工艺参数磨削后工件表面粗糙度的仿真值与试验结果吻合度较好,为实际砂带磨削工艺参数的选择和优化提供理论依据与参考。     

外圆超声振动研磨Al2O3陶瓷的去除率研究

研究了Al2 O3 陶瓷试件的超声振动研磨特征 ,分析超声研磨中加工参数与试件材料去除率的关系。经研究得出 :在相同的加工条件下 ,超声振动研磨加工比普通研磨加工 ,材料去除效率高 ,去除率随工件转速的增加而增加 ,随着转速的增加 ,去除率的斜率有所下降 ;保证材料去除率达到最大的研磨压力存在一个最佳值 ;粗粒度油石研磨加工去除效率较细粒度的高 ;细磨粒油石超声研磨工件表面粗糙度值小于粗磨粒研磨工件。同时与普通研磨相比较 ,超声研磨加工不仅效率高、且加工工件表面粗糙度值较小。     

金刚石线锯横向超声振动切割SiC单晶表面 粗糙度预测*

把横向超声振动应用到金刚石线锯切割硬脆材料加工中,基于冲量原理分析了线锯横截面上不同位置处金刚石磨粒对工件的法向锯切力。应用压痕断裂力学理论,定量分析了在法向和切向载荷共同作用下磨粒下方中位/横向裂纹扩展的长度和深度。研究了振动磨粒在工件上间歇加载和卸载使横向裂纹优先扩展并抑制中位裂纹扩展的屏蔽效应。建立了横向振动线锯切割硬脆材料时线锯横截面不同位置处磨粒的材料去除模式模型,得到了横向振动线锯切割硬脆材料晶片表面粗糙度的预测公式。以SiC单晶为切割对象,进行普通线锯和横向超声振动线锯切割对比试验,测定线锯的锯切力和晶片表面粗糙度,并对表面形貌进行观察。结果表明,横向超声振动线锯切割SiC是以脆性去除为主塑性去除为辅的混合材料去除模式;同等试验条件下,超声振动线锯切割能使晶片表面粗糙度降低25.7%。表面粗糙度测试结果与理论预测具有较好的一致性。     

横向超声振动对金刚石线锯切割硬脆材料锯切力及临界切削深度的影响

硬脆晶体材料,如SiC、Ge和Si等,由于其临界切削深度极小,常规加工方法很难实现塑性模式加工,研究横向超声振动金刚石线锯对硬脆材料锯切力和临界切削深度的影响有重要意义。在研究线锯受迫振动的基础上,分析金刚石线锯在横向超声波激励下柔性旋转点切割硬脆材料的条件;用特征函数对超声激励下金刚石线锯的振动切割状态进行表征;应用磨削理论建立了单颗金刚石磨粒切割硬脆材料的力学模型;推导出超声振动激励下金刚石线锯锯切硬脆材料临界切削深度的计算公式。以单晶SiC为对象,进行了超声振动线锯切割和普通线锯切割对比试验。结果表明相同条件下,超声振动线锯切割SiC的锯切力比普通线锯的锯切力减少22.4%~64.2%,临界切削深度增加1倍,晶片表面粗糙度有明显的改善。试验结果与理论分析具有良好的一致性。     

Effects of particle size, polishing pad and contact pressure in free abrasive polishing

The objective of this research is to better understand the mechanisms of material removal in the free abrasive polishing process. Experiments were carried out to understand the effects of particle size, polishing pad and nominal contact pressure on the wear rate and surface roughness of the polished surface. A theoretical model was developed to predict the relationship between the polishing parameters and the wear rate for the case of hard abrasive particles sandwiched between a soft pad and a workpiece (softer than the abrasive particles). Experimental results and theoretical predictions indicate that the wear rate increases with an increase in particle size, hardness of polishing pad and nominal contact pressure, and with a decrease in elastic modulus of the polishing pad. Surface roughness increases with an increase in particle size and hardness of polishing pad, and nominal contact pressure has little effect on the roughness. A dimensionless parameter, wear index which combines all of the preceding parameters, was introduced to give a semi-quantitative prediction for the wear rate in free abrasive polishing. It is also suggested that when polishing hard material, in order to achieve a high materials removal rate and a smooth surface, it is preferable to use diamond as the polishing particles because of their high deformation resistance.     

砂轮约束磨粒喷射精密光整加工材料去除机理研究

基于磨粒特征尺寸与砂轮、工件间液膜厚度比值的变化,研究了砂轮约束磨粒喷射精密光整加工材料去除机理。分析了在两体加工及三体加工模式条件下,单颗磨粒运动特点以及磨粒由两体研磨加工向三体抛光加工转变的临界条件。实验证明,砂轮约束磨粒喷射光整加工中,随着加工循环的增加,工件表面微观形貌变化规律与理论分析相同,实验结果和理论分析吻合很好。     

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.     

Surface roughness and material removal rate of lapping process on ceramics

Lapping is a widely used surface finishing process for ceramics. An experimental investigation is conducted into the lapping of alumina, Ni−Zn ferrite and sodium silicate glass using SiC abrasive to study the effect of process parameters, such as abrasive particle size, lapping pressure, and abrasive concentration, on the surface roughness and material removal rate during lapping. A simple model is developed based on the indentation fracture and abrasive particle distribution in the slurry to explain various aspects of the lapping process. The model provides predictions for the surface roughness,R _a andR _t , on the machined surface and rough estimation for the material removal rate during lapping. Comparison of the predictions with the experimental measurements reveals same order of magnitude accuracy.     

Modeling and simulation of magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced finishing processes, which produces a high level of surface quality and is primarily controlled by a magnetic field. In MAF, the workpiece is kept between the two poles of a magnet. The working gap between the workpiece and the magnet is filled with magnetic abrasive particles. A magnetic abrasive flexible brush (MAFB) is formed, acting as a multipoint cutting tool, due to the effect of the magnetic field in the working gap. This paper deals with the theoretical investigations of the MAF process. A finite element model of the process is developed to evaluate the distribution of magnetic forces on the workpiece surface. The MAF process removes a very small amount of material by indentation and rotation of magnetic abrasive particles in the circular tracks. A theoretical model for material removal and surface roughness is also proposed accounting for microcutting by considering a uniform surface profile without statistical distribution. Numerical experiments are carried out by providing different routes of intermittent motion to the tool. The simulation results are verified by comparing them with the experimental results available in the literature.     

Modeling and simulation of magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced finishing processes, which produces a high level of surface quality and is primarily controlled by a magnetic field. In MAF, the workpiece is kept between the two poles of a magnet. The working gap between the workpiece and the magnet is filled with magnetic abrasive particles. A magnetic abrasive flexible brush (MAFB) is formed, acting as a multipoint cutting tool, due to the effect of the magnetic field in the working gap. This paper deals with the theoretical investigations of the MAF process. A finite element model of the process is developed to evaluate the distribution of magnetic forces on the workpiece surface. The MAF process removes a very small amount of material by indentation and rotation of magnetic abrasive particles in the circular tracks. A theoretical model for material removal and surface roughness is also proposed accounting for microcutting by considering a uniform surface profile without statistical distribution. Numerical experiments are carried out by providing different routes of intermittent motion to the tool. The simulation results are verified by comparing them with the experimental results available in the literature.     

砂轮约束磨粒喷射加工表面材料去除机理

基于磨粒特征尺寸与砂轮、工件间液膜厚度比值的变化研究了磨粒喷射光整加工的材料去除机理,建立了两体研磨及三体冲蚀单颗磨粒的材料去除模型和材料去除率模型。试验在MB1332A外圆磨床上完成,加工试样为Sa=06μm左右的45钢。加工表面形貌和微观几何参数分别用SEM和MICROMESVRE2表面轮廓仪测量,试验结果和材料去除模型相吻合。试样表面连续的方向一致的沟槽被随机不连续的微坑所代替,随着加工循环的增加,Sa值由06μm下降到02μm左右。此外,光整加工可以获得各向同性网纹交错的表面,表面轮廓的支撑长度率提高,对工件的耐磨性有利。 