电火花线切割电规准对SKD11加工的影响

为了研究电火花线切割加工SKD11时电规准对表面粗糙度和材料去除率的影响规律,选取脉冲放电时间、脉冲间隙时间、峰值电流和间隙电压为试验因素,表面粗糙度和材料去除率为试验指标做单因素试验。结果表明:随着脉冲放电时间的增加,材料去除率随之增加,而表面粗糙度增大;脉冲间隙时间增加时,材料去除率减少,但表面粗糙度减小,当脉冲间隙时间为35μs时到达最小;峰值电流对两个试验指标影响跟脉冲放电时间一致;随着间隙电压的增大,材料去除率增大,表面粗糙度同时也增大。     

铝合金阳极氧化膜的集群磁流变平面抛光试验研究

为获得抛光均匀的铝合金阳极氧化膜表面,采用集群磁流变平面抛光技术对铝合金阳极氧化膜进行抛光试验,探讨加工间隙、工件转速、抛光盘转速、偏摆幅度、加工时间等加工参数对其表面粗糙度和材料去除率的影响规律。结果表明:随着加工间隙的增大,工件表面粗糙度先减小后增大,材料去除率则递减;随着工件转速或偏摆幅度的增加,工件的表面粗糙度均先迅速减小后缓慢增大,材料去除率则先增加后减小;随着抛光盘转速的增加,工件的表面粗糙度和材料去除率均先减小后增加;随着加工时间的延长,表面粗糙度迅速减小之后趋于稳定。在文中试验条件下,在加工间隙1. 1 mm、工件转速350 r/min、抛光盘转速60 r/min、偏摆幅度10 mm、加工10 min左右时工件表面粗糙度从原始的332. 9 nm下降至5. 2 nm,达到了镜面效果。     

充磁与未充磁烧结钕铁硼电火花加工对比试验研究

钕铁硼硬度高、脆性大,且充磁后具有高磁性力.电火花加工是钕铁硼的重要加工方法.为探寻充磁与未充磁烧结钕铁硼在电火花加工过程中的工艺差异和规律,采用单因素试验方法,开展对比试验,研究放电参数(脉冲宽度、峰值电流和脉冲间隔)对充磁与未充磁烧结钕铁硼的材料去除率、表面粗糙度和重铸层的影响.结果 表明:随脉冲宽度的增加,充磁烧结钕铁硼的材料去除率增大,而未充磁烧结钕铁硼的材料去除率先增大后略有减小,充磁与未充磁烧结钕铁硼表面粗糙度值均增大,重铸层均增厚且内部出现裂纹;随峰值电流的增加,两者材料去除率和表面粗糙度值均增大;随脉冲间隔的增加,两者材料去除率和表面粗糙度值均减小;在较大的放电参数值下,充磁烧结钕铁硼的材料去除率和表面粗糙度明显优于未充磁烧结钕铁硼.     

充磁与未充磁烧结钕铁硼电火花加工对比试验研究

钕铁硼硬度高、脆性大,且充磁后具有高磁性力.电火花加工是钕铁硼的重要加工方法.为探寻充磁与未充磁烧结钕铁硼在电火花加工过程中的工艺差异和规律,采用单因素试验方法,开展对比试验,研究放电参数(脉冲宽度、峰值电流和脉冲间隔)对充磁与未充磁烧结钕铁硼的材料去除率、表面粗糙度和重铸层的影响.结果 表明:随脉冲宽度的增加,充磁烧结钕铁硼的材料去除率增大,而未充磁烧结钕铁硼的材料去除率先增大后略有减小,充磁与未充磁烧结钕铁硼表面粗糙度值均增大,重铸层均增厚且内部出现裂纹;随峰值电流的增加,两者材料去除率和表面粗糙度值均增大;随脉冲间隔的增加,两者材料去除率和表面粗糙度值均减小;在较大的放电参数值下,充磁烧结钕铁硼的材料去除率和表面粗糙度明显优于未充磁烧结钕铁硼.     

氮化硅陶瓷滚子磁流变、化学与超声复合抛光工艺试验

为实现氮化硅陶瓷滚子抛光的高效、高精度要求,提出磁流变、化学与超声复合的抛光工艺方法。分析复合抛光的加工机理;利用试验机,在不同工艺参数下进行了复合抛光工艺试验,分析各主要工艺参数对抛光材料去除率和滚子表面粗糙度的影响规律,确定出复合抛光的最佳工艺参数。结果表明:复合抛光后陶瓷滚子表面粗糙度Ra由0.3μm减小至0.03μm;在最佳工艺参数下,滚子能够在保持较高材料去除率的同时获得较好的表面质量;材料去除过程主要是磁流变抛光的剪切作用、超声波抛光的冲击作用以及抛光过程中一系列化学反应综合作用的结果。     

蓝宝石基片的单面研磨工艺研究

为了实现蓝宝石基片的快速平坦化,对蓝宝石基片进行系统的单因素单面研磨试验,研究了磨料种类、磨料粒径、研磨盘转速、研磨压力以及磨料质量分数等研磨工艺参数对蓝宝石基片材料去除率和表面粗糙度的影响规律。试验结果表明:金刚石磨料适合蓝宝石基片的单面研磨;随着磨料粒径的增大,材料去除率逐渐增大,表面越来越粗糙;随着研磨盘转速的增大,材料去除率先增大后减小,表面粗糙度值在20～60 r/min区间变化不大,稳定在Ra 0. 12～Ra 0. 13μm之间,而在60～100 r/min区间波动较大,当研磨盘转速为60 r/min时,材料去除率最大;随着研磨压力的增大,材料去除率逐渐增大,而表面粗糙度值越来越低;随着磨料质量分数的增大,材料去除率先增大后减小,表面粗糙度先增大然后趋于平缓,当磨料质量分数为3 wt%时,材料去除率最大,且表面粗糙度值相对较小;最后通过正交试验优化了工艺参数,在优化的工艺条件下依次选用粒径为W40、W14、W3的金刚石磨料对蓝宝石基片进行粗研、半精研及精研,取得了表面粗糙度为Ra 7. 9 nm的平坦表面。     

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。     

GCr15轴承钢电火花线切割工艺参数优化

为了提升GCr15轴承钢电火花线切割加工的表面质量,研究了峰值电流、脉宽时间和脉间时间对GCr15轴承钢电火花线切割加工效果的影响。结果表明:材料的表面粗糙度和去除率随峰值电流和脉宽时间的增大而增大,脉间时间对表面粗糙度的影响不大,当脉间时间过小时,容易发生加工短路现象。对电火花线切割加工工艺参数进行了优化,峰值电流为2 A、脉宽时间为1μs、脉间时间为4μs时,加工效果最佳,表面粗糙度Ra值为0.76μm,加工效率为10.1 mm~2/min。     

磷化铟的动态磁场集群磁流变抛光工艺实验

为实现磷化铟高质量表面的绿色加工,使用动态磁场集群磁流变抛光对单晶磷化铟进行正交抛光实验,研究各工艺参数（抛光盘转速、工件转速、磁极转速和偏摆速度）对抛光速率及抛光表面粗糙度的影响。利用回归分析法建立反映材料去除率及表面粗糙度与抛光工艺参数关系的回归方程。结果显示：在抛光工艺参数中,工件转速对材料去除率影响最大,偏摆速度影响最小;对表面粗糙度影响最大的是抛光盘转速,磁极转速影响最小;在优化工艺参数（抛光盘转速40 r/min、工件转速500 r/min、磁极转速30 r/min、偏摆速度200 mm/min）下对单晶磷化铟抛光3 h后,表面粗糙度由Ra33 nm降至Ra 0.35 nm,材料去除率为2.5 μm/h,表明采用动态集群磁流变抛光的方法加工单晶磷化铟,可以得到高质量加工表面;建立的材料去除率及表面粗糙度回归模型,拟合优度判定系数分别为0.984 2和0.937,表明利用回归分析法建立的磷化铟磁流变抛光的材料去除率及表面粗糙度回归模型,能够有效地预测磷化铟集群磁流变抛光效果。     

基于响应曲面法的YG8硬质合金刀片化学机械抛光工艺参数优化

为了快速确定YG8前刀面抛光的最佳工艺参数,提高加工效率和精度,利用响应曲面法对YG8硬质合金刀片抛光工艺进行优化试验研究。通过单因素试验确定抛光转速、抛光压力、磨粒粒径和磨粒浓度的水平,并对4个工艺参数进行中心复合设计试验。建立了材料去除率RMR和表面粗糙度Ra的预测模型,基于响应曲面法优化工艺参数获得最佳工艺参数为抛光转速65.5 r/min、抛光压力156.7 kPa、磨粒粒径1.1 μm、磨粒浓度14%,此时得到了最小表面粗糙度预测值Ra=0.019 μm,材料去除率RMR=56.6 nm/min。试验结果表明,基于响应曲面法的材料去除率与表面粗糙度预测模型准确有效。     

高体积分数SiCp/Al复合材料旋转超声铣磨加工的试验研究

由于大量高硬度增强相SiC颗粒的存在,高体积分数铝基碳化硅（SiCp/Al）复合材料的机械加工十分困难。旋转超声加工被认为是加工这种材料的有效方法。通过超声辅助划痕试验,分析高体积分数SiCp/Al复合材料旋转超声铣磨加工的材料去除机理。在超声振动的作用下,材料中铝基体发生塑性变形,其表面得到夯实;SiC增强相被锤击成细小的颗粒而发生脱落,形成较大的空洞。由于材料加工的缺陷大多产生于SiC颗粒的去除过程中,SiC颗粒的去除方式对加工表面的质量起着决定性的作用,选择合适的工艺参数可以有效提高加工表面质量。旋转超声加工工艺特征试验表明,超声振动可有效降低切削力;主轴转速对轴向切削力的影响最大,其次是进给速度,切削深度对轴向切削力的影响较小;另外主轴转速对表面质量的影响效果也最大,并随主轴转速的增大表面粗糙度增大。因此在加工过程中,可以适当加大切削深度,在保证加工质量的基础上,选择较大的进给速度,在保证刀具寿命的前提下,选择合适的主轴转速,以获得较优的加工表面质量和加工效率。     

基于RSM的SiC单晶片表面粗糙度预测及参数优化

通过响应面分析法(RSM)对超声振动辅助金刚石线锯切割SiC单晶体的工艺参数进行分析和优化。采用中心组合设计实验,考察线锯速度、工件进给速度、工件转速和超声波振幅这4个因素对SiC单晶片表面粗糙度值的影响,建立了SiC单晶片表面粗糙度的响应模型,进行响应面分析,采用满意度函数(DFM)确定了切割SiC单晶体的最佳工艺参数,验证试验表明该模型能实现相应的硬脆材料切割过程的表面粗糙度预测。     

Research into the transition of material removal mechanism for C/SiC in rotary ultrasonic face machining

Ceramic matrix composites of type C/SiC with superior properties have got increasing importance in many fields of industry, especially in the aerospace area. Rotary ultrasonic machining is a high-efficiency processing technology for these advanced materials. However, due to the inhomogeneity and anisotropy of these composites, the machining process is still challenging to achieve desired result due to the lack of understanding and control of material removal mechanism. In this paper, the maximum depth of penetration by diamond abrasives in workpiece material is proposed to quantify the material removal modes. A model of maximum depth of penetration for rotary ultrasonic face machining (RUFM) was developed based on the indentation theory. An experimental RUFM of C/SiC was carried out, and it revealed that the material removal mechanism transited from ductile mode to brittle fracture mode with the decrease of cutting speed. Similar transition was observed with the increase of feed rate and cutting depth. By comparing the measured cutting force with simulation, a critical depth of penetration for the cutting mechanism transition was defined at about 4 μm. The processed surface topography was studied, and the transition of material removal modes was identified by the sudden change of the 3D surface roughness map at the critical penetration depth. Thus, the maximum depth of penetration model developed in this paper can be applied to identify the ductile or brittle fracture removal mode in RUFM of C/SiC using the cutting parameters. This allows controlling the material removal mechanism to achieve desired machining efficiency and quality.     

超声振动磨削陶瓷材料高效去除机理研究

基于压痕断裂力学,在工件横向施振超声振动平面磨削单颗磨粒受力分析基础上,建立了材料去除率综合数学模型;并就超声振动和普通磨削进行了对比试验研究。研究结果表明超声振动磨削陶瓷材料去除率与被加工材料的种类、磨削深度、砂轮磨粒粒度、超声振动的振幅以及磨削条件有着密切关系。同样磨削条件下,超声振动磨削陶瓷材料去除率是普通磨削的1.7~3.2倍,与理论模型相符合。试验结果表明超声振动磨削可以获得良好的加工表面,工件横向施振超声振动磨削是一种精密、高效加工新工艺。     

纤维方向对单向C/SiC复合材料磨削加工性能的影响

为了研究碳纤维编织复合材料的去除机理,探明纤维编织方向对磨削加工性能的影响,设计并制备了单向复合材料C/SiC,并沿纤维典型方向进行了磨削实验。结果表明,单向复合材料磨削时,切向磨削力和法向磨削力均呈如下规律：法向磨削＞纵向磨削＞横向磨削;磨削加工过程中表面粗糙度值呈如下规律：纵向磨削＞法向磨削＞横向磨削。对加工表面显微形貌的分析,揭示了陶瓷基复合材料微观多向去除机理。     

超声振动辅助固结磨粒抛光硅片表面形成机理及实验

基于超声加工所具有的加工效率和加工表面质量高等特性,提出了一种超声振动辅助固结磨粒化学机械复合抛光硅片新技术。对抛光工具及复合抛光实验系统的建立进行了描述,在此基础上开展硅片抛光表面形貌及材料去除机理的理论及实验研究,得到不同抛光力下的研究结果。所建立的理论模型及实验结果表明,超声振动辅助固结磨粒抛光有利于硅片表面质量及材料去除率的提高,且随着抛光力的增大,抛光表面质量下降,材料去除效果提高。     

Experimental research on machining characteristics of SiC ceramic with end electric discharge milling

Silicon carbide (SiC) ceramic has been widely used in modern industry. However, the beneficial properties of SiC ceramic make machining difficult and costly by conventional machining methods. This paper proposes a new process of machining SiC ceramic using end electric discharge (ED) milling. The process is able to effectively machine a large surface area on SiC ceramic at low cost and no environmental pollution. The effects of emulsion concentration, emulsion flux, milling depth, copper electrode number, and copper electrode diameter on the process performance such as the material removal rate, electrode wear ratio, and surface roughness have been investigated. In addition, the microstructure of the machined surface is examined with a scanning electron microscope, and the material removal mechanism of SiC ceramic during end ED milling is obtained.     

Modeling and Optimization of Machining Process in Discontinuously Reinforced Aluminium Matrix Composites

This article presents development of an Artificial Neural Networks (ANN) based model for the prediction of surface roughness during machining of composite material using Back Propagation algorithm. Statistically designed experiments based on Taguchi method were carried out on machining of Al/SiCp composite material. The experimentation helped generate a knowledge base for the ANN system and understand the relative importance of process, tool and work material dependent parameters on the roughness of surface generated during machining. The ANN model trained using the experimental data was found to predict the surface roughness with fair accuracy. An optimization approach was also proposed to obtain optimal cutting conditions that yield the desired surface roughness while maximizing the metal removal rate.     

Free abrasive wire saw machining of ceramics

Currently, many kinds of ceramics are used in advanced industrial fields due to their superior mechanical properties, such as thermal, wear, corrosion resistance, and lightweight features. Wire saw machining ceramic (Al₂O₃) was investigated by ultrasonic vibration in this study. Taguchi approach is a powerful design tool for high-quality systems. Material removal rate, wafer surface roughness, steel wire wear, kerf width, and flatness during machining ceramic were selected as quality character factors to optimize the machining parameters (swinging angle, concentration, mixed grain and direction of ultrasonic vibration) to get the larger-the-better (material removal rate) and the smaller-the-better (wafer surface roughness, steel wire wear, kerf width and flatness) machining characteristics by Taguchi method. The results indicated that wire swinging produces a higher material removal rate and good wafer surface roughness. Ultrasonic vibration improved material removal rate, without affecting the flatness under different machining conditions. Experimental results show that the optimal wire saw machining parameters based on grey relational analysis can be determined effectively and material removal rate increases from 2.972 to 3.324 mm²/min, wafer surface roughness decreases from 0.37 to 0.34 μm, steel wire wear decreases from 0.78 to 0.77 μm, kerf width decreases from 0.352 to 0.350 mm, and flatness decreases from 7.51 to 7.22 μm are observed.     

Effect of turning parameters on surface roughness of A356/5% SiC composite produced by electromagnetic stir casting

In the present investigation, A356 alloy 5 wt% SiC composite is fabricated by electromagnetic stir casting process. An attempt has been made to investigate the effect of CNC lathe process parameters like cutting speed, depth of cut, and feed rate on surface roughness during machining of A356 alloy 5 wt% SiC particulate metal-matrix composites in dry condition. Response surface methodology (Box Behnken Method) is chosen to design the experiments. The results reveal that cutting speed increases surface roughness decreases, whereas depth of cut and feed increase surface roughness increase. Optimum values of speed (190 m/min), feed (0.14 mm/rev) and depth of cut (0.20 mm) during turning of A356 alloy 5 wt% SiC composites to minimize the surface roughness (3.15μm) have been find out. The mechanical properties of A356 alloy 5 wt% SiC were also analyzed.