非混粉电火花镜面加工及表面质量检测

采用解析法和有限元分析方法,分析了各因素对电火花加工表面质量的影响,提出了一种在电火花放电加工过程中逐级改变加工电规准,并依次加大电极的摇动量进行镜面加工的方法.提出应用白光干涉方法测量镜面加工工件表面质量的微观形貌,具有非接触、高精度等特点,垂直分辨力达到纳米级.实验表明在非混粉加工液中,不更换电极且被加工工件为45#钢的情况下,利用白光干涉测量法检测出电火花镜面加工的工件表面粗糙度Ra为0.02μm,满足电火花镜面加工精度的要求.     

IN718镍基高温合金电火花加工表面完整性初步研究

镍基合金具有优良的性能而获得广泛的应用,针对切削加工中存在的问题,采用与材料的力学性能无关的电火花进行加工,通过对其电火花加工实验,初步研究了峰值电流和脉冲宽度加工参数对加工表面完整性的影响规律。结果表明,表面粗糙度随峰值电流和脉冲宽度的增大而增大,与电极丝的运动方向无关。加工表面由微观组织规则的凹坑、熔滴和微小孔组成,加工表面无微观裂纹存在。显微硬度变化不大,无加工硬化现象。随脉冲能量减小,重铸现象减轻,加工表面完整性越好。     

BP神经网络在电火花成形加工中的应用

针对电火花成形加工工艺特点,以峰值电流、脉冲间隔、脉冲宽度、峰值电压为输入参数,加工速度、电极损耗和表面粗糙度为输出参数,提出了用BP神经网络对电火花成形加工过程建立加工效果预测模型,通过计算机仿真的结果与实验数据对比,认为该模型能够比较精确地预测出一定条件下的加工速度、电极损耗和表面粗糙度,并能真实反映出机床的加工工艺规律。     

多脉冲飞秒激光精修面齿轮的烧蚀形貌研究

针对材质为18Cr2Ni4WA的面齿轮,采用飞秒脉冲激光烧蚀来提高其表面质量。建立电子-自旋-晶格三温复耦合模型,预测分析面齿轮材料电子、自旋和晶格单脉冲能量效应下的温度变化过程;结合多脉冲能量累积效应,进行面齿轮材料在激光能量密度为1.035~5.252 J/cm2下烧蚀凹坑直径和深度演变规律的预测与实验分析。研究结果表明：脉冲数的增加并不会持续增大面齿轮表面的平衡温度,基本在30个脉冲时就保持不变;能量密度的增加会使烧蚀凹坑直径和深度持续变大,但变大的速率会持续降低;烧蚀凹坑形貌在能量密度为2.467 J/cm2时最好;过大的扫描道间距会使被加工表面粗糙度值增加,扫描道间距为25 μm时粗糙度值最低为0.185 μm。     

ELID精密磨削钢结硬质合金及其AFM表面形貌分析

对钢结硬质合金（GT35）进行在线电解修整（ELID）精密磨削,对钢结硬质合金难磨机理以及ELID磨削钢结硬质合金的磨削机理进行了分析,并通过原子力显微镜（AFM）对镜面钢结硬质合金表面不同区域进行了微观表面形貌的分析,研究结果表明,采用ELID磨削技术实现对钢结构硬质合质合金零件的精密磨削加工,钢结硬质合金磨削表面粗糙度可达nm级,Ra≤20nm。     

先进陶瓷材料超声振动铣磨加工表面粗糙度仿真及实验(英文)

为了对超声振动铣磨加工先进陶瓷的表面粗糙度进行预测,建立了加工表面形貌的仿真模型.通过实验测得砂轮表面形貌和磨粒突出高度信息,并对这些信息进行Kolmogorov-Smirnov正态验证,发现砂轮表面形貌不服从高斯分布.对非高斯分布的数据进行Johnson变换,建立砂轮形貌的数值模型.结合砂轮表面形貌和磨粒与工件的相对运动分析,提出了一种表面轮廓搜索方法,进而生成了加工表面的三维形貌.最后,在DMG ULTRASONIC 70-5 linear机床上进行切削实验,对仿真结果进行了验证,结果表明仿真与实验结果具有较好的一致性,并对仿真误差产生的原因进行了分析.     

30CrMnSiA在内孔镗削加工中表面轮廓曲线变化规律研究

在切削速度25~200m/min范围内,使用涂层硬质合金刀具对高强度钢30CrMnSiA进行了内孔镗削实验,对比研究了干镗削与油润滑条件下加工表面粗糙度轮廓曲线的特征信号构成及其对形状参数Ra和Ry的影响规律。研究表明:在实验条件范围内,油性切削液对表面粗糙度指标Ra和Ry值没有显著影响,且随切削速度的改变,在干镗削与油润滑条件下,表面轮廓曲线的变化趋势基本相同;切削润滑条件的改变将对20~40μm波长尺度的特征轮廓曲线产生影响。     

单晶金刚石机械研磨与化学机械抛光工艺

单晶金刚石在工业、国防等领域的应用日益广泛,对其加工表面质量的要求不断提高,使用常温低压的化学机械抛光可实现金刚石的超光滑低损伤表面加工.通过理论分析及实验研究得出,使用硅酸盐玻璃材质研磨盘进行研磨加工,可以将金刚石表面粗糙度Ra降至15~25 nm,且无明显机械划痕;在2 MPa压力及室温环境下进行单晶金刚石化学机械抛光实验,优选出Fenton试剂酸性水基抛光液,使用该抛光液抛光单晶金刚石可获得粗糙度Ra值4 nm以下的光滑表面.     

凹坑体积对中碳钢织构表面摩擦磨损特性的影响

为了改善高速钢表面的摩擦磨损性能,采用钻削加工的方法,在45钢表面加工出不同深度的凹坑织构,进行凹坑织构表面与GCr15的摩擦磨损试验,测量了摩擦系数和磨损量,观察了试件磨痕表面,分析了凹坑体积对织构表面摩擦磨损性能的影响。结果表明:凹坑织构表面的摩擦系数和磨损量首先随着凹坑体积的增加而减小,当凹坑体积达到某一值后,摩擦系数和磨损量不再随着体积的增加而减小;凹坑织构的容屑作用有助于提高织构表面的摩擦磨损特性; 45钢在磨损过程中存在磨屑的搭桥覆盖现象,影响了凹坑的容屑能力,限制了凹坑织构表面耐磨性能的提高。     

面向精密加工的仿真技术研究及应用

详细阐述了计算机仿真技术在精密加工领域中应用的两个方面——加工过程动态仿真和加工过程物理特性仿真;建立了微细电火花加工仿真系统,实现微细电火花放电通道仿真,建立并分析了电火花加工的热学模型,分析了表面粗糙度与工艺参数的关系。系统在实际中得到验证,加工出微三维结构。通过电火花仿真系统,说明计算机仿真技术在精密加工研究方面的可行性和优越性。     

Study of the Effect of Machining Parameters on the Machining Characteristics in Electrical Discharge Machining of Fe-Mn-Al Alloy

In this work we investigated the electrical discharge machining (EDM) of a Fe-Mn-Al alloy. The surface phenomena caused by EDM were studied in terms of machining parameters. An empirical model of the Fe-Mn-Al alloy was also proposed based on the experimental data. Experimental results indicate that the higher the discharge energy, the faster the machining time. This treatment introduces machining damage in the resolidified surface layer and worsens the surface roughness. The optimum pulse-on duration on the basis of the electrode wear ratio for the copper electrode was about 200 μs. The increase of crater depth with the applied pulsed current and pulse-on duration appears minimal under a small input energy.     

Electrical Discharge Machining (EDM) Characteristics Associated with Electrical Discharge Energy on Machining of Cemented Tungsten Carbide

In this investigation, cemented tungsten carbides graded K10 and P10 were machined by electrical discharge machining (EDM) using an electrolytic copper electrode. The machining parameters of EDM were varied to explore the effects of electrical discharge energy on the machining characteristics, such as material removal rate (MRR), electrode wear rate (EWR), and surface roughness. Moreover, the effects of the electrical discharge energy on heat-affected layers, surface cracks and machining debris were also determined. The experimental results show that the MRR increased with the density of the electrical discharge energy; the EWR and diameter of the machining debris were also related to the density of the electrical discharge energy. When the amount of electrical discharge energy was set to a high level, serious surface cracks on the machined surface of the cemented tungsten carbides caused by EDM were evident.     

Effect of electrical discharge machining on the characteristics of carbon fiber reinforced carbon composites

This work investigated electrical discharge machining (EDM) of carbon fiber reinforced carbon composite material. The characteristics of composites machined by EDM were studied in terms of machining parameters. An empirical model of the composites was also proposed based on the experimental data. The composite material was produced by an electrical discharge sinker using a graphite electrode. The workpiece surface and resolidified layers were examined by scanning electron microscopy (SEM). Moreover, surface roughness was determined with a surface profilometer. Experimental results indicate that the extent of delamination, thickness of the recast layer, and surface roughness are proportional to the power input. The EDM process effectively produces excellent surface characteristics and high quality holes in composites under low discharge energy conditions.     

Electro-Discharge Machining–A Qualitative Approach

The complex and stochastic nature of Electro-Discharge Machining (EDM) has drawn numerous investigations to establish control over the quality related characteristics such as better surface finish, smaller heat-affected zone including minimized recast layer without compromising the productivity of the machining process. The present paper proposes a three-dimensional transient heat conduction model where the growth of the plasma channel is considered. The temperature distribution function is used to compute the depth of the crater that defines the surface roughness (Ry) and depth of the heat-affected zone at different pulse duration. Further, experiments are conducted to measure the depth of the crater and the depth of the heat-affected zone. The experimental and theoretical results show significant similarity.     

Constrained multi-objective optimization of EDM process parameters using kriging model and particle swarm algorithm

This paper investigates the highly nonlinear relationship between process parameters and machining responses, including material removal rate (MRR), surface roughness (SR), and electrode wear rate (EWR) of electric discharge machining (EDM) using Kriging model. Subsequently, an emerging multi-objective optimization algorithm called particle swarm is used to determine the best machining conditions that not only maximize the machining speed but also minimize the EWR with a constraint of the SR. The experiment was carried out with P20 steel on a CNC EDM machine using copper electrode. The research result shows that the MRR increases sharply when increasing the discharge current just like other researches pointed out. However, the relationship between EWR and current is complicated. EWR appears the minimum value when the current is around 30?A. The speed of change of MRR per unit of EWR is the highest when the SR is around 14.5?µm. The combination of Kriging regression model and particle swarm optimization is considered as an intelligent process modeling and optimization of EDM machining. The proper selection of process parameters helps the EDM operator to reduce the machining time and cost.     

SURFACES OF ADVANCED CERAMIC COMPOSITES FORMED BY ELECTRICAL DISCHARGE MACHINING

Ceramic composites shaped by electrical discharge machining were examined by several analytical techniques, including scanning electron microscopy, XPS, elemental distribution maps, and hardness testing, to determine changes due to EDM and to compare these surfaces to those obtained by other machining methods. Preferential oxidation was observed for some composites, while others showed no chemical changes. Correlations for material removal rate, surface roughness, and diameter to depth ratio for the crater were developed.     

Performance analysis of a thick copper-electroplated FDM ABS plastic rapid tool EDM electrode

The importance of rapid tooling (RT) and additive manufacturing (AM) appears to be indispensable for boosting the process of manufacturing and expanding the horizon of production technology worldwide. This concept draws the attention of numerous scholars to arrive at a conclusive theory for the widespread utilization of RT. This study attempts to determine the viability and performance of an RT electrode in the field of electro discharge machining (EDM). The electrode prototype is made using an acrylonitrile butadiene styrene (ABS) plastic by fused deposition modeling (FDM), an AM technique, electroplated with copper of desired thickness, and used in die sinking EDM of D2 steel. The scanning electron microscope analysis of the electroplated samples confirms that it is possible to obtain the desired thickness of the metal by electroplating on any electrically conductive surface. In the present work, an experimental study is performed for examining the electroplated copper thickness of the plastic EDM electrode and its performances. It is found that the electroplated ABS plastic EDM RT electrode successfully performs the machining operation of D2 steel, and the results are comparable with a solid electrode. The study reveals that the RT electrode can be regarded as a viable tool for rough cutting or semi-finishing cut EDM functions. The experimental results are thoroughly discussed, examined, analyzed, and evaluated for the purpose of developing the appropriate form of the concept.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0238-5     

冷喷涂颗粒在铸铁和Q235钢表面沉积过程的数值分析

核废料储存装置需长久埋于地下,其材料(包括低碳钢、Cu、Ti、镍基合金及不锈钢等)的防腐设计至关重要。以铸铁和Q235钢的防腐蚀为出发点,采用有限元方法,分析了冷喷涂制备铸铁表面铜涂层和Q235钢表面不锈钢涂层的沉积特性。结果表明,颗粒的速度越大,其扁平程度越高,基板上凹坑深度越深;最大塑性变形、最大应力以及最大温度分布位置为粒子与基板的接触部位,温度分布与塑性应变分布一致;撞击过程中,能量在粒子和基板间发生转移与转化。     

空气介质微细电火花沉积加工微结构机理

对微细电火花沉积加工中沉积所得不同微细结构的成形机理进行了研究．在电火花成形机床上，通过合理选择工艺参数，用黄铜电极在高速钢工件表面稳定沉积出外径约0．20mm、线径约0．09mm的微螺旋结构和直径约0．20mm微圆柱体．通过有限元法对工具电极放电点的瞬态温度场进行了模拟，分析结果表明，不同的放电能量密度影响材料的蚀除形式，继而影响蚀除电极材料在放电通道中的运动，最终影响微细结构的成形过程．对沉积材料微观组织结构分析表明，沉积材料与基体结合层为冶金结合方式，结合紧密，并由于凝固过程极大的冷却速率，使沉积材料在凝固过程中发生了晶粒细化现象．     

Study on the machining of Al–SiC functionally graded metal matrix composite using die-sinking EDM

Functionally graded aluminum matrix composites (FGAMCs) are new materials with excellent capabilities for design and development of complex engineering works. In this work, FGAMCs are machined using electrical discharge machining (EDM) with the process input parameters such as pulse current, pulse on time, and zone position in brake disk. Design of experiments is used for the experimental planning with full factorial method. The selected input process parameters are optimized using gray relational analysis to minimize the electrode wear ratio, overcut, power consumption, and surface roughness. The influential studies of input process parameters on the output responses are also conducted. The optimal EDM parameter setting for achieving better output parameters is pulse current at 5 A, pulse on time at 50?µs and 45?mm zone position distance in the brake disk. The pulse current (39.40%) contributed the maximum in minimizing the output responses. Further, the surface morphology is also analyzed on the material to observe the crater formation and the erosion mechanism.