放电能量对线切割加工表面质量的影响

在电火花线切割加工中,放电能量(电流的峰值和脉宽)在很大程度上影响被加工面的表面粗糙度,为了找出它们之间的规律,用有限元法对电火花线切割的加工蚀除进行了热分析,分析和实验结果表明,具有相同脉冲能量的放电电流,虽然表面粗糙度一样,但表面形貌不一样,在精加工时,更适合选用窄脉宽、高峰值的放电电流。     

基于正交试验法的往复走丝线切割多次切割工艺的研究

针对影响往复走丝电火花线切割多次切割的因素较多,采用正交试验的方法,进行放电脉宽、脉间、峰值电流、运丝速度、工作液及每次切割的偏移量对往复走丝电火花线切割3次切割的影响试验,确定影响加工效率和加工表面粗糙度的显著影响因素水平,优化加工参数,进行5次切割试验验证,获得工件加工表面粗糙度Ra0.69μm,加工的重复性较好。     

电火花线切割加工参数对加工速度和表面粗糙度影响的研究

讨论了电火花线切割加工中影响加工速度和表面粗糙度的几个主要参数:脉冲宽度、峰值电流、脉冲间隔及工件厚度,并通过正交试验分析了加工参数对加工速度、表面粗糙度的影响关系,为科学、合理地设定电火花线切割加工参数提供了参考。     

基于Cr12MoV模具钢的准干式电火花线切割研究

为了探究以水雾作为介质的准干式电火花线切割精加工特性,本文进行了以水雾、大气、乳化液分别作为介质的对比实验。实验以偏移量和水雾量为可变参数,分别研究了工件精加工阶段的切割速度、表面粗糙度和表面形貌。结果表明,在精加工阶段准干式电火花线切割加工的切割速度、表面粗糙度和表面形貌接近于干式电火花线切割加工而明显好于液中加工,并且准干式电火花线切割加工的工件表面有较少的熔融液滴反粘,但加工表面出现了少许的电解作用产生的小孔。     

电火花线切割大电流条件下电参数对加工性能的影响

为了解决往复走丝电火花线切割加工效率低的问题,对大电流条件下的两种电加工参数进行了研究,在保证平均电流相同的条件下,对小脉宽、大峰值电流和大脉宽、小峰值电流两种加工方式进行对比实验。结果表明:在普通往复走丝电火花线切割机床上,采用大脉宽、小峰值电流加工方式,其加工效率比小脉宽、大峰值电流的高约20%;采用小脉宽、大峰值电流的加工方式能有效地减少工件表面的烧伤,获得表面粗糙度值较小的加工表面。此外还分析了两种加工方式的放电加工机理,从放电通道扩展半径、放电频率和电极间放电状态等角度解释了两种方式的加工效率和表面质量差异。     

放电参数对线切割加工A8工具钢表面粗糙度与材料去除率的影响

A8工具钢是一种高硬度高韧性的难加工材料,常用电火花线切割来加工处理。电火花线切割加工A8工具钢实际生产过程中,表面粗糙度和材料去除率分别是加工表面质量和加工效率的重要指标,放电参数直接影响到表面粗糙度和材料去除率。在几组生产中常用的放电参数(加工电流、脉冲宽度、脉冲间隙)条件下,加工A8工具钢,分别得到每种放电参数对表面粗糙度和材料去除率的具体影响规律,结果表明:随着加工电流的增大,加工后材料表面粗糙度和材料除去率同时增大且趋势相似;随着脉冲宽度的增大,加工后材料表面粗糙度和材料除去率同时增大;随着脉冲间隙的增大,材料除去率呈递减趋势,加工后材料表面粗糙度前期递减,在脉冲间隔8μs后减小趋势放缓,在脉冲间隔10μs时达到最小值,在脉冲间隔大于10μs后略有升高,变化幅度不大。研究结果为实际生产中电火花线切割加工A8工具钢提供技术参考,可以根据不同的生产要求选择合适的放电参数组合。     

成对电极法电解光亮加工

<正> 电火花线切割和电火花成型加工所得的表面粗糙度往往很难满足模具的技术要求。尽管日本的若干厂商已能制造出加工表面最低粗糙度接近Ra0.1μm的电火花线切割机和Ra0.05μm的电火花成型加工机但是为了获得这样低的加工表面粗糙度,其加工效率由于要用十分微小的放电能量加工而大大降低,况且在大面积成型加工时还难以实现。再者,其加工表面还难免存在微细裂纹和变质层,影响模具的使用寿命。至于像塑料模具等所要求的表面光泽则更难以实现。因此人们     

超声水雾中电火花线切割精加工特性研究

实验采用的水雾介质为超声水雾,通过大气、乳化液和超声水雾介质中往复走丝电火花线切割精加工对比实验,对超声水雾介质中往复走丝线切割精加工特性进行了研究,针对表面粗糙度、切割速度、直线度、表面形貌和火花率等指标进行了系统的分析,实验结果表明,超声水雾介质中二次切割加工的表面质量介于气中与液中之间,而优于液中加工。提出了在精加工阶段采用气体或水雾介质的电火花线切割多次切割工艺,经实验验证,传统乳化液中三次切割获得的表面粗糙度为2.81μm,而采用乳化液-超声水雾-大气组合的三次切割新工艺方法获得的表面粗糙度为2.42μm,与介质均采用乳化液的传统三次切割工艺相比,该新工艺方法将表面粗糙度值降低了0.39μm,能有效改善加工表面质量。     

工作液电导率对MSWEDM加工工艺性指标影响研究

通过实验方法研究了工作液电导率对中走丝电火花线切割机床加工工艺性指标的影响。分析了工作液电导率对加工状态(加工电压、加工电流)的影响规律;分析了工作液电导率对切割速度、表面粗糙度和加工精度(尺寸精度、腰鼓形和形状精度)工艺性指标的影响规律,从而确定了精加工工作液电导率上限值,保证中走丝电火花线切割机床工作液智能交换控制的可行性。     

TC4钛合金电火花线切割加工工艺参数的影响研究

为研究电火花线切割加工工艺参数对TC4钛合金材料加工质量的影响,采用单因素试验法,分析脉宽、放电间隙、功率放大管数及变频值等工艺参数对TC4钛合金切割速度与表面粗糙度的影响规律.试验结果表明,不同参数变化对材料的切割速度与表面粗糙度有不同影响.     

Influence of discharge current on machined surfaces by thermo-analysis in finish cut of WEDM

In finish machining of wire electrical discharge machining (WEDM), the discharge current has distinct influences on the machined surface. In order to study the differences in surface morphology under various pulse durations, thermo-analysis was carried out to investigate the mechanism of erosion of the workpiece material using the finite element method. Additionally, related single discharge experiments under different pulse energies were performed. Under the same discharge energy, the comparison of analytical and experimental results shows that a discharge current with a short-duration pulse and a high peak value removes the workpiece material mainly by gasifying, while a discharge current with a long-duration pulse and low peak value removes the workpiece material mainly by melting. It was also found that surfaces machined by a discharge current with a short- and long-duration pulses would have similar roughness values when the pulse energies were almost the same and were high enough; however, the surface morphologies would be totally different. A discharge current with a long pulse duration and a low peak value could not produce craters on the workpiece surface when the pulse energy was reduced to a certain value. However, a discharge current with a short pulse duration and a high peak value could produce clear craters on the workpiece surface. This indicates that a discharge current with a short pulse duration and a high peak value can generate better surface roughness, which cannot be achieved with a current with a long pulse duration and a low peak value.     

旋转电极接触力对电火花沉积放电过程参数和材料转移的影响

为了研究旋转电极接触力对电火花沉积放电过程参数和材料转移的影响,进行了不同接触力下的电火花自动沉积试验.分析了不同接触力下的各种放电波形的数量、放电脉冲的平均电压和电流等放电参数、电火花沉积的转移效率和沉积效率、沉积层的表面形貌和截面形貌、表面粗糙度等.结果表明,接触力的变化影响了旋转电极电火花自动沉积过程中各种放电类型的数量和比例.随着接触力的增大,接触放电比例逐渐减少而短路放电比例逐渐增加,放电脉冲的平均电压和平均功率逐渐下降而平均电流逐渐上升.接触力对电火花沉积的转移效率和沉积效率影响较大,对表面粗糙度影响不大.接触力为1～2 N时,自动沉积过程中的接触放电比例较高,转移效率和沉积效率也较高.在旋转电极电火花自动沉积过程,接触放电引起的材料转移量明显高于短路放电引起的材料转移量.     

Surface modification of Al–Zn–Mg alloy by combined electrical discharge machining with ball burnish machining

The study investigated the feasibility of modifying the surface of Al–Zn–Mg alloy by a combined process of electric discharge machining (EDM) with ball burnish machining (BBM). A novel process that integrates EDM and BBM is also developed to conduct experiments on an electric discharge machine. Machining parameters of the combined process, including machining polarity, peak current, power supply voltage, and the protruding of ZrO₂, are chosen to determine their effects on material removal rate, surface roughness and the improvement ratio of surface roughness. In addition, the extent to which the combined process affects surface modification is also evaluated by microhardness and corrosion resistance tests. Experimental results indicate that the combined process of EDM with BBM can effectively improve the surface roughness to obtain a fine-finishing and flat surface. The micropores and cracks caused from EDM are eliminated during the process as well. Furthermore, such a process can reinforce and increase the corrosion resistance of the machined surface after machining.     

Improvement of surface finish on SKD steel using electro-discharge machining with aluminum and surfactant added dielectric

Electrical discharge machining (EDM) process is widely used to process hard materials in the industry. Electrical discharge distribution effects can be achieved by the addition of Al powder in the dielectric. A fine surface roughness value of the workpiece is thus obtained. However, the electrostatic force among fine Al particles is found to agglomerate the Al powders in the dielectric. A surfactant can be adopted to separate the Al powder in the dielectric homogenously. A better surface even the mirror-like quality of the EDMed workpiece is thus desired. In the study, the effect of surfactant and Al powders added in the dielectric on the surface status of the workpiece after EDM is investigated.It is observed the best distribution effect is found when the concentrations of the Al powder and surfactant in the dielectric are 0.1 and 0.25 g/L, respectively. An optimal surface roughness (Ra) value of 0.172 μm is achieved under the following parameter—positive polarity, discharge current 0.3 A, pulse duration time 1.5 μs, open circuit potential 140 V, gap voltage 90 V and surfactant concentration 0.25 g/L.The surface roughness status of the workpiece has been improved up to 60% as compared to that EDMed under pure dielectric with high surface roughness Ra of 0.434 μm.     

An investigation of ultrasonic-assisted electrical discharge machining in gas

This study focuses on using ultrasonic to improve the efficiency in electrical discharge machining (EDM) in gas medium. The new method is referred to as ultrasonic-assisted electrical discharge machining (UEDM). In the process of UEDM in gas, the tool electrode is a thin-walled pipe, the high-pressure gas medium is applied from inside, and the ultrasonic actuation is applied onto the workpiece. In our experiment, the workpiece material is AISI 1045 steel and the electrode material is copper. The experiment results indicate that (a) the Material Removal Rate (MRR) is increased with respect to the increase of the open voltage, the pulse duration, the amplitude of ultrasonic actuation, the discharge current, and the decrease of the wall thickness of electrode pipe; and (b) the surface roughness is increased with respect to the increase of the open voltage, the pulse duration, and the discharge current. Based on experimental results, a theoretical model to estimate the MRR and the surface roughness is developed.     

Study on the characteristics of electrical discharge machining using dielectric with surfactant

This research mainly explores the influence of surfactant on the characteristics of electrical discharge machining (EDM) process on mold steel (SKD61). In this study, particle agglomeration is reduced after surfactant molecules cover the surface of debris and carbon dregs in kerosene solution. Debris is evenly dispersed in dielectric to improve the effects of carbon accumulation and dreg discharge, and reduce the unstable concentrated discharge. The EDM parameters, such as peak current, pulse duration, open voltage and gap voltage are studied in this paper. The experimental results show that after the addition of Span 20 (30 g/L) to dielectric, the conductivity of dielectric is increased. The machining efficiency is thus increased due to a shorter relay time of electrical discharge. When proper working parameters are chosen, the material removal rate is improved by as high as 40–80%. Although the improvement of surface roughness is not obvious, the surface roughness is not deteriorated since the material removal rate is great.     

304 不锈钢电火花线切割加工表面性能研究

目的研究电火花线切割工艺对金属材料加工表面质量的影响规律,分析加工表面的机械性能。方法利用电火花线切割加工技术,对304不锈钢工件进行表面切割试验,应用马尔轮廓测量仪、扫描电镜、超景深电子显微镜及纳米压痕仪观察电火花加工表面的粗糙度变化规律和表面微形貌特征,获取横截面纳米硬度变化曲线。设计正交试验,获得最优加工参数。结果脉冲宽度和峰值电流对奥氏体不锈钢加工表面形貌的形成机制有显著影响,加工表面粗糙度受电参数的影响较大,加工表面的表层及次表层组织主要由塑性变形层与回火多相组织层共同构成,厚度与纳米硬度的变化受电参数的影响较大。结论电参数对表面质量的影响程度顺序为脉冲宽度、峰值电流、放电间隔,为得到较优加工表面层,应优先选择脉冲宽度为16μs,放电间隔为96μs,峰值电流为1.5 A的工艺参数组合。单个脉冲能量对加工层的厚度以及表层的纳米硬度呈现出近似线性规律。     

聚晶立方氮化硼刀具刃口放电加工工艺研究

通过调整电火花加工的主要放电参数（脉冲宽度和加工电流）,对聚晶立方氮化硼（PCBN）4~进行放电加工,进而对样刀刃口表面进行x射线衍射分析,并在扫描电子显微镜下观察其表层结构及能谱分析。通过对加工后样刀表面变质层主要成分及产生原因的分析,总结了脉冲宽度和加工电流对样刀表面变质层厚度、刃口表面粗糙度影响的关系曲线,为制定精密快速放电加工PCBN刀具的工艺提供了重要依据。