工件超声振动电火花线切割复合加工试验研究

借助ANSYS软件对变幅杆、夹具和工件进行整体的动力学研究,设计了一套超声振动电火花线切割复合加工装置。在相同加工参数下,分别采用工件超声振动电火花线切割复合加工和传统的电火花线切割加工对45钢进行切割试验。试验结果表明:与传统的电火花线切割加工相比,超声振动电火花线切割复合加工的效率提高了约15%,表面粗糙度减小了约10%。     

利用新型工作液和改进电极提高电火花加工性能的试验

针对电火花小孔加工中加工速度低、电极损耗严重、工件产生斜度和棱角变钝等缺陷,提出了改进小孔工具电极、研制新型工作液以提高电火花加工性能的具体措施,并在电火花机床上进行了试验。通过大量的试验研究得出:在相同的电参数下,与传统工艺相比,采用新型工作液作为介质并配有改进的电极进行电火花小孔加工时,其加工速度大幅提高、电极损耗与工件锥度有所降低,从而提高了电火花加工性能。     

分流法小孔电火花加工与试验

介绍一种等面积分流法的小孔电火花加工方法,分析等面积电极放电的电火花加工过程,重点研究在等面积电极条件下,等面积单电极与分流多电极加工对加工速度、电极损耗、放电间隙的影响。进行了验证性试验,研究结果表明：小孔分流法加工与单电极加工相比,使加工速度略有减小、放电间隙略有变小、电极损耗略有增加,加工效果具有一致性;分流法电火花加工有利于小孔电火花加工的尺寸控制,通过等面积分流法改变加工工艺,用电火花机床稳定加工参数进行小于机床稳定加工临界值的更小尺寸的小孔加工,是一种新的微小孔电火花加工方法。     

微小孔超声电火花复合加工通孔变幅杆设计

超声电火花复合加工在微小孔制备方面应用颇多,其常见问题有:在生产同一批零件更换电极丝时,不能保证二次装夹的精度;加工过程中,电蚀废屑堆积会造成各种不良影响等.基于以上问题设计了一种轴心通孔式变幅杆,并在变幅杆两端增加两个定位螺柱.为保证微小孔加工的精度和圆度,选择了两种稳定性高的变幅杆(悬链线形和圆锥形)进行分析.将预...     

复合电极与分散剂工作液电火花小孔加工工艺研究

小孔加工是电火花加工的一种应用技术,在难加工和异形孔加工中有着独特的优势,目前已被广泛应用。这种技术存在的缺陷是随着被加工孔深径比的增加,加工效率下降,工具电极损耗加大,不能最大限度地满足生产需要。为了克服以上缺陷,提出复合电极与分散剂工作液电火花小孔加工工艺。制作了复合电极和分散剂工作液,在D703F电火花小孔加工机床上进行了加工实验,结果表明:合理选用复合电极和分散剂工作液,可以有效提高加工速度、降低电极相对损耗,而被加工孔的深径比也有显著提高,该工艺可为合理选择工具电极和工作液提供具体工艺参数并且对实现"高效低损耗"加工具有一定现实意义。     

钛合金深小孔超声电火花加工工艺与实验研究

针对钛合金深小孔加工的技术难点,研制了具有四轴联动功能的微细超声电火花加工机床,在所研制的机床上,进行了钛合金深小孔超声电火花复合加工实验,就超声振动及削边电极在加工中的作用进行了系统和研究。     

螺旋电极电火花小孔加工排屑仿真和试验

在电火花小孔加工中,排屑困难一直是困扰加工速度的一个重要问题。通过对工具电极改进,用螺旋电极进行电火花小孔加工,使其改变加工过程中间隙流场的流动状态以及电蚀产物的受力,达到增强小孔加工过程中的排屑能力,进而提高加工速度的目的。利用Gambit软件建立仿真模型,应用Fluent对小孔加工过程中排屑进行仿真,对其压力场和速度场进行分析,研究其加工机理。在D703F高速电火花小孔加工机床上进行了试验研究,结果表明螺旋电极电火花小孔加工速度最大提高了20%。     

旋转超声电解复合加工小孔的仿真加工

为研究旋转超声电解复合加工小孔的成型过程,进行了旋转超声电解复合加工小孔试验,得到了不同加工时间孔的截面,并根据试验参数,进行了基于ANSYS的二维仿真加工和三维仿真加工。对小孔的入口直径、底面直径和加工深度进行了对比分析,结果表明由于三维仿真加工中采用了管电极,并考虑了电解加工中阴极超声高频振动对电解液电导率的影响,故其仿真结果更加接近试验值,间接证明了旋转超声电解复合加工小孔三维仿真加工的可靠性,展示了不同时刻的三维加工型腔,为旋转超声电解复合加工的成型过程和成型规律的研究提供了参考。     

超声复合微细电火花加工机理与试验

微结构电火花加工短路、断路或电弧放电作用,降低加工效率及精度。提出将超声频振动与微细电火花加工复合,利用电极与工件之间的超声频相对运动,产生规则的、参数可控的微细脉冲放电;构造、完善超声复合微细电火花试验系统,进行微结构超声复合电火花加工试验,有效避免短路、断路及电弧脉冲,有效提高加工精度与效率。TG662     

复合PAAS工作液与工件半浸液的深小孔电火花加工工艺

现有电火花小孔机床在加工大深径比小孔时存在加工稳定性差、小孔质量差、相对电极损耗率大等技术难点。深入分析D703F电火花小孔加工机床的原理及特点,实验证明使用一定浓度分散剂聚丙烯酸钠(PAAS)作为工作液可大幅提高小孔加工速度、降低相对电极损耗,但随着加工小孔深径比变大,孔内加工环境变差、散热困难,PAAS工作液会产生碳化现象反而阻碍了正常加工。用PAAS工作液和工件半浸液复合的方法,使工件在加工时能良好散热,减缓PAAS工作液的碳化现象,正常发挥分散作用,从而达到高速加工大深径比小孔的目的。     

分散剂在电火花小孔加工中的作用机理及试验研究

从研究水分散剂的分散机理入手,分析研究了水分散剂对电火花小孔加工的排屑、加工速度和加工质量的影响。通过电火花小孔加工中采用自来水工作液和分散剂工作液的加工效果对比,发现在电火花小孔加工的水基工作液中加入一定比例的分散剂后,不仅使电火花小孔加工的加工速度提高、电极相对损耗降低,而且有效脉冲数增加,二次放电数明显减少,工具电极作用端和被加工孔的锥度变小,加工质量提高。     

Analysis of rotary electrical discharge machining characteristics in reversal magnetic field for copper-en8 steel system

The material removal rate (MRR), along with the electrode wear rate (EWR), plays an important role in analysing machine output during electrical discharge machining. This work focuses on the improvement of machine output by introducing an induced magnetic field on the workpiece during rotary electrical discharge machining (REDM) of EN-8 steel with a rotary copper electrode. The workpiece was placed inside the induced magnetic field, wherein polarity of the magnetic field gets reversed periodically. Using Taguchi’s recommended design of experiments, we initially conducted experiments with eight input parameters at different levels . Significant parameters were identified with the help of the signal-to-noise ratio and ANOVA. Finally, another set of experiments was conducted for analysis of the process and development of empirical expressions for MRR and EWR. Experimental results established that rotary electrical discharge machining with a polarity reversal magnetic field delivers better machining output than machining in a non-magnetic field. Thus, this work benefits the EDM process by reducing the machining costs and by producing better geometrical trueness on workpieces, as MRR increased and EWR decreased.     

Soft computing models based prediction of cutting speed and surface roughness in wire electro-discharge machining of tungsten carbide cobalt composite

This paper reports on an experimental investigation of small deep hole drilling of Inconel 718 using the EDM process. The parameters such as peak current, pulse on-time, duty factor and electrode speed were chosen to study the machining characteristics. An electrolytic copper tube of 3 mm diameter was selected as a tool electrode. The experiments were planned using central composite design (CCD) procedure. The output responses measured were material removal rate (MRR) and depth averaged surface roughness (DASR). Mathematical models were derived for the above responses using response surface methodology (RSM). The results revealed that MRR is more influenced by peak current, duty factor and electrode rotation, whereas DASR is strongly influenced by peak current and pulse on-time. Finally, the parameters were optimized for maximum MRR with the desired surface roughness value using desirability function approach.     

Feasibility study of micro-slit EDM machining using pure water

This study addresses micro-slit EDM machining feasibility using pure water as the dielectric fluid. Experimental results revealed that pure water could be used as a dielectric fluid and adopting negative polarity EDM machining could obtain high material removal rate (MRR), low electrode wear, small slit expansion, and little machined burr, compared to positive polarity machining. In comparing kerosene versus pure water, pure water was observed to cause low carbon adherence to the electrode surface. Also discharge energy does not decrease and the discharge processes are not interrupted. Therefore, MRR was higher, and related electrode wear ratio compared to kerosene use was lower. In a continual EDM with multi-slit machining, kerosene will cause carbon element adherence, creating an initially high MRR and electrode wear, with rapid decline. However, pure water will not cause carbon element adherence on the electrode surface, so MRR and electrode wear is always stable in this process.     

铝基碳化硅异形电极电火花加工技术研究

为了改善电火花深小孔加工过程中,因加工碎屑排出不畅而导致的加工速度慢、电极损耗严重等问题,制备螺旋、三沟槽和削边三种形貌的异形结构电极。在相同的加工条件下,以铝基碳化硅为实验材料,采用异形结构电极与圆柱电极分别进行不同深度下深小孔加工实验,对加工效率、电极损耗和深小孔内表面形貌三方面进行对比分析。实验结果表明:异形结构电极在深小孔的加工效率和电极损耗方面都优于圆柱电极;小孔内表面形貌方面:圆柱电极加工后的孔内表面附着碎屑较多。     

气体放电加工基础工艺试验研究

采用单因素法进行了基本的工艺参数(电参数、伺服参考电压等)对气体介质放电加工性能影响的试验研究。试验结果表明:气体介质的放电加工适于采用正极性加工。在试验加工的范围内,工件的蚀除速度和表面粗糙度值随脉冲宽度和峰值电流的增加而增加,随脉冲间隔的增加而减小。极间并联合适的电容能够使加工速度和加工表面粗糙度有所改善,并对此现象进行了分析。对于某一确定的加工参数,存在一个较佳的伺服参考电压值,使加工性能较为稳定。工具电极具有较高的旋转速度能够使气体放电加工性能得到提高。使用氧气介质能够实现快速电火花加工,并根据不同气体的物理性能对不同气体介质的加工性能进行了分析。工件表面显微硬度测试结果表明:空气中放电加工的工件的表面硬度比基体硬度高,比煤油中加工的工件表面硬度低。     

Sinking EDM in water-in-oil emulsion

In this paper, a new type of sinking electric discharge machining (EDM) dielectric–water-in-oil (W/O) emulsion is proposed, and the machining characteristics of W/O emulsion are investigated by comparing with that of kerosene. In the experiments, machining parameters such as the dielectric type, peak current, and pulse duration are changed to explore their effects on machining performance, including the material removal rate (MRR), relative electrode wear rate (REWR), and surface roughness. Experimental results revealed that W/O emulsion could be used as the dielectric fluid of sinking EDM and adopting long pulse duration and large peak current could lead to obtaining higher MRR than kerosene. Compared with kerosene, W/O emulsion is observed to cause lower carbon adhered to the electrode surface. Therefore, its REWR is higher. Statistics of the discharge waveform show that more stable discharge processes can be obtained by using W/O emulsion compared with kerosene. Furthermore, W/O emulsion is more economical and more environmentally friendly than kerosene, and it could be an alternative to kerosene in sinking EDM application.     

Optimal parameter settings for rough and finish machining of die steels in powder-mixed EDM

The present study was undertaken to identify the appropriate parameter settings for rough and finish machined surface for EN31, H11, and high carbon high chromium (HCHCr) die steel materials in a powder-mixed electric discharge machining process. The effect of seven different process variables along with some of their interactions was evaluated using a dummy-treated experimental design and analysis of variance. Material removal rate (MRR), tool wear rate, and surface finish were measured after each trial and analyzed. The parameter settings for rough and finished machining operations were obtained. EN31 exhibited maximum MRR as compared to the other two materials at similar process settings. Copper (Cu) electrode with aluminum suspended in the dielectric maximized the MRR. Suspending powder in the dielectric resulted in surface modification. Graphite powder showed a lower MRR but improved the surface finish. HCHCr require higher current and pulse on settings for initiating a machining cut and works best in combination with tungsten–Cu electrode and graphite powder for improved finish. The MRR for H11 is lower than EN31 but significantly higher than HCHCr under same process conditions.     

Study of the effects of tool longitudinal oscillation on the machining speed of electrochemical discharge drilling of glass

In this study, longitudinal oscillation applied to the cathode electrode during the electrochemical discharge micro drilling of glass and the effects of electrolyte flushing alteration in both discharge and hydrodynamic regimes of the process have been investigated. In this regard, numerous sets of experiments have been conducted using different vibration frequencies and amplitudes. In addition, two geometrically different tools including cylindrical rod and micro drill were used as machining electrode (cathode). In the case of cylindrical rod, two types of longitudinal waveforms including square and sinusoidal ones were applied to the tool. The experiments were resulted in a noticeable improvement in material removal rate (MRR) using square waveform and a slight improvement in the case of sinusoidal waveform. Moreover, the obtained MRR by means of vibrating micro drill has been compared with those achieved by non-vibrating one in several oscillation frequencies and amplitudes. The results showed that the vibration of the micro drill cannot further improve the electrolyte flushing and MRR in comparison with non-vibrating one because of the inherent electrolyte flushing in micro drill through its flutes which is constant in vibrating and non-vibrating cases.     

Research on the influence of dielectric characteristics on the EDM of titanium alloy

This study investigated the influences of dielectric characteristics, namely, electrical conductivity, oxidability, and viscosity on the electrical discharge machining (EDM) of titanium alloy. A new kind of compound dielectric with optimal processing effect was developed based on the identified effects. Comparative experiments on titanium alloy EDM in compound dielectric, distilled water, and kerosene were performed to analyze the difference in material removal rate (MRR), relative electrode wear ratio (REWR), and surface roughness (SR). The experimental results revealed that titanium alloy EDM in compound dielectric achieved the highest MRR, a lower REWR than that in kerosene, and better SR and fewer micro-cracks than that in distilled water.