去离子水中电火花毛化技术工艺试验研究

在煤油和去离子水中,针对9Cr2Mo轧辊钢进行了电火花毛化加工试验。通过对数据的对比分析,研究了在不同工作液条件下,脉宽和峰值电流的变化对加工件表面粗糙度和单位面积上凹坑数的影响规律。结果表明,去离子水更适用于电火花毛化加工。     

深微孔电火花加工非电参数工艺规律研究

在深微孔电火花加工中,工作液及电极材料等非电参数的选择对加工效率及加工质量有极大的影响,揭示这些非电参数的工艺规律对提高深微孔电火花加工性能有重要的研究意义.利用煤油和去离子水两种工作液,以加工效率为目标,在不同条件下开展工艺试验,得出最适宜的工作液在加工45钢和紫铜材料工件时为去离子水,加工铝合金材料工件时为煤油;利用黄铜丝、钨丝及钼丝3种电极材料,同样以加工效率为目标开展工艺试验,得出最佳电极材料在加工45钢工件时为钨,加工紫铜材料工件时为钨和钼,加工铝合金材料工件时为黄铜.上述研究在深微孔电火花加工中合理选择工作液及电极材料方面做出了有益的探索,其研究成果为深微孔电火花加工高效率、高质量的开展提供了重要的借鉴.     

微细液态添加剂对电火花加工性能影响的实验研究

研究了微细液态添加剂对电火花加工中放电过程的影响。与单纯工作液中的放电过程相比,微细液态工作液中单位时间内有效脉冲数增多,平均击穿延时缩短,而火花维持电压相对较低,表明加入了微细添加剂的工作液在提高电火花加工性能方面具有潜力。实验结果显示,微细液态添加剂能有效提高工件的材料去除率,显著降低表面粗糙度值,并明显减少了加工表面的显微裂纹。     

微细液态添加剂光整电火花加工技术初探

提出了一种在普通电火花工作液中加入微细液态添加剂进行电火花光整加工的新方法.初步的试验结果表明,此法能显著改善工件的表面粗糙度,达到镜面效果.从液相添加剂的作用机理对微细液态添加剂电火花加工改善表面粗糙度的原因进行了解释.     

基于微纳乳液的Inconel718电火花成形加工工艺实验研究

采用自制的微纳乳液作为工作液,利用电火花成形加工镍基高温合金(Inconel718),选取峰值电流、脉冲宽度、脉冲间隔及单次加工时间等参数进行十字正交试验,研究分析这些参数对电火花成形加工Inconel718的表面粗糙度和材料去除率的影响,并对比了在微纳乳液与煤油工作液中加工的工件表面微观形貌。结果表明:峰值电流对材料去除率影响显著,单次加工时间对表面粗糙度影响显著;与煤油工作液相比,采用微纳乳液进行电火花成形加工的工件表面质量更好。     

半导体硅材料的电火花加工技术研究

从硅材料的物理性能出发，分析其微细电火花加工的可行性。对未掺杂单晶硅和掺杂N型硅进行了电火花加工工艺试验，得出了掺杂N型硅有很好的微细电火花加工性能的结论。硅材料在电火花加工机理上除了熔化与汽化外，还有比较明显的热剥蚀作用。因此提高硅表面加工质量，必须将单脉冲放电能量控制得尽可能的低。     

Al2O3陶瓷电火花磨削工作液实验研究

考虑到工作液对于非导电工程陶瓷双电极同步伺服电火花磨削新工艺的重要性,以氧化铝陶瓷加工为例,通过实验的方法研究了工作液的种类、浓度对材料去除率和加工表面粗糙度的影响规律,给出了实验步骤,并对实验结果进行了理论分析。综合考虑加工效率、加工质量、成本及环保等因素,在自来水中配制5%体积浓度的DX-1乳化液是比较理想的工作液。考虑单一效果,在自来水乳化液加入0.5%质量的聚乙烯醇作工作液可以提高材料去除率10%以上;使用去离子水作工作液可以得到最好的表面质量。     

松香对电火花线切割加工的影响

在去离子水和三乙醇胺组成的工作液中,按质量比逐步添加松香,在保证机床及其它工艺参数不变的前提下,观察松香含量对加工效率及表面粗糙度的影响.实验证明:增加松香的含量,可以提高加工效率和改善表面粗糙度.     

微喷部件阵列孔电火花加工工艺试验研究

比较各种微细阵列孔的电火花加工方法,分析了单电极加工微细阵列孔方法的优点。以去离子水作为工作液,在已研制成功的微喷部件阵列孔电火花加工机床上进行单电极加工微细阵列孔的工艺试验,研究电源参数对微细阵列孔的孔径一致性、加工效率及电极损耗的影响规律。优化微细阵列孔加工的电参数,实现稳定的一次性加工256个直径小于50μm、偏差小于2μm的微细阵列孔。     

高速走丝电火花线切割加工中工作液的电解作用

测定了高速走丝电火花线切割加工中添加电解质的工作液电导率与加工效率及表面粗糙度的关系，表明随着电导率增加，工件表面粗糙度下降，加工效率存在最佳值。通过测定电极丝的损耗曲线，证实工作液的电解镀覆作用能减少电极丝的损耗和增加其寿命。     

A study on the fine-finish die-sinking micro-EDM of tungsten carbide using different electrode materials

In recent years, tungsten carbide (WC) and its composites (WC–Co) are widely used in the die and mold industries due to their unique combination of hardness, strength and wear resistance. Micro-EDM is one of the most effective methods for machining these extremely difficult-to-cut materials. However, numerous applications of WC often involve intense mechanical demands at the surface. Therefore, fine-finish micro-EDM of WC is becoming an imminent and important issue. In this study, investigations have been conducted with view of obtaining fine surface finish in the micro-EDM of WC using tungsten (W), copper tungsten (CuW) and silver tungsten (AgW) electrodes. It was found that the surface characteristics are dependent mostly on the discharge energy during machining. The fine-finish micro-EDM requires minimization of the pulse energy supplied into the gap. In addition, the surface finish was found to be influenced greatly by the electrical and thermal properties of the electrode material. The performance of the electrodes for the finishing micro-EDM was evaluated based on the achieved surface roughness and surface characteristics with respect to material removal rate (MRR) and electrode wear ratio (EWR). It was found that AgW electrode produces smoother and defect-free nanosurface with the lowest R_a and R_max among the three electrodes. Besides, a minimum amount of material migrates from the AgW electrode to the WC workpiece during the finishing micro-EDM. On the other hand, CuW electrodes achieved the highest MRR followed by AgW. In the case of electrode wear, the W electrode has the lowest wear followed by CuW and AgW. Finally, considering all the performance parameters, AgW appears to be the best choice for finish die-sinking micro-EDM of WC.     

Investigation of the effects of electrode orientation and fluid flow rate in near-dry EDM milling

This research investigates the effects of electrode lead and tilt angles and dielectric fluid flow rate on material removal rate, tool electrode wear ratio, and surface roughness in near-dry electrical discharge machining (EDM) milling process. Computational fluid dynamics (CFD) model is developed to predict the dielectric fluid flow rate and qualitatively compare with the experimentally measured EDM material removal rate. The optimum lead angle, which maximized material removal rate and minimized tool electrode wear ratio, was found. The decrease in the lead angle has a negative effect on the roughness of machined surface. The increase in tilt angle reduces the material removal rate and increases the tool electrode wear ratio. The change in tilt angle does not have a significant effect on the surface roughness and can be used to prevent gouging in finishing EDM milling. This study shows that the material removal rate is linearly proportional to the mass flow rate of air and kerosene mixture, the tool electrode wear ratio is inversely related to the mass flow rate of air and kerosene mixture, and the average surface roughness does not have a good correlation with the flow rate of the mixture.     

电极丝随动放电切槽技术试验研究

微细电火花线切割加工时电极丝存在难以避免的振动,且振动幅度随着切割工件厚度的增加而变大,这导致加工出现腰鼓形误差,工件加工效率与加工质量也受影响.针对电极丝的振动问题提出一种电极丝随动放电切槽技术,通过顶丝头的导丝孔和导丝槽抑制电极丝振动,利用电极丝放电蚀除工件完成了长度70 mm、直径0.1 mm的半圆截面长通道的加...     

单层多道微细电火花定长补偿加工方法

定长补偿是应用分层原理进行微细电火花加工的一种方法,它能较好地解决加工中电极损耗对精度的影响问题.通过实验证明了微细电火花铣削加工中由于底面和侧面放电间隙不同,在加工过程中要区别对待;根据实验结果建立了实际加工后单道的横截面模型,在此基础上引入了体积系数、面积系数、残切系数,对原来的定长补偿方法进行了修正.根据建立的实际加工后残切模型,给出2种典型去除残切的加工工艺路线,应用定长补偿方法解决了分层三维构件加工中的单层加工问题.     

A study on microgrinding of brittle and difficult-to-cut glasses using on-machine fabricated poly crystalline diamond (PCD) tool

Present study aims to investigate the feasibility of microgrinding difficult-to-machine glass materials with Poly Crystalline Diamond (PCD) tool, which is fabricated on-machine using micro-electrodischarge machining (micro-EDM). A detailed experimental investigation on the mechanism of the process including the effect of micro-EDM machining conditions on tool surface and the effect of grinding parameters on microgrinding performance are presented. In this context, a comparative study on the microgrinding performance of three glass materials (BK7, Lithosil and N-SF14) using on-machine fabricated PCD tool was carried out. It was found that during tool fabrication using micro-EDM process, higher discharge energy generates rougher surface and larger craters on the tool, which can provide higher material removal rate (MRR) during grinding but results in poorer surface finish on glass surface. In addition to micro-EDM conditions of tool fabrication, the roughness of the ground glass surface depends greatly on grinding parameters such as depth of cut, feed rate and tool rotational speed. The surface roughness increases with increasing axial depth of cut and feed rate, whereas higher rotational speed was found to improve the surface finish. Among three types of glass materials, BK7 glass was found to provide better performance in terms of the achieved surface finish and cutting force analysis.     

A study on micro-hole machining of polycrystalline diamond by micro-electrical discharge machining

Polycrystalline diamond (PCD), with its superior wear and corrosion resistance, is an ideal material for micro-hole parts in the field of microfabrication. This study investigated the micro-hole machining performance for PCDs by micro-electrical discharge machining (micro-EDM). A series of experiments were carried out to investigate the proper machining polarity and the impacts of micro-EDM parameters on machining performance. Experimental results indicate that negative polarity machining is suitable for micro-EDM of PCDs because of the protection brought over by the adhesion sticking to the electrode. An appropriate volume of adhesion on the tool electrode can help to increase the material removal rate (MRR) and reduce the relative tool wear ratio (TWR). By contrast, an excessive volume of adhesion can lead the machining into a vicious circle in which micro-holes are drilled with overlarge diameters. An optimal set of machining conditions was chosen among the investigated ranges of nominal capacitance and electrode rotation speed. An exemplary PCD through-hole, machined under the chosen optimal machining conditions, shows satisfactory machining results.     

硬脆材料的环形电镀金刚石线锯加工试验研究

本文利用环形电镀金刚石线锯对硬脆材料单晶硅、LT55陶瓷进行了切割试验,研究了锯切力、材料加工表面质量及锯丝的磨损.研究发现,在相同加工参数下,切割LT55陶瓷时的法向力与切向力之比小于单晶硅,与磨削相比,线锯加工的法向力与切向力之比非常小;在本实验条件下,单晶硅和LT55陶瓷均为脆性去除方式;因为LT55陶瓷断裂韧性高,在同样加工条件下,陶瓷加工表面质量优于单晶硅;恒进给压力条件下,锯丝速度增加,粗糙度值略微减小,恒进给压力增加,粗糙度值明显增大;锯丝首先在焊口处断裂,由于锯丝不能自转,沿锯丝圆周方向磨损不均匀.     

线速度对金刚石线锯及硅片表面质量的影响

为了考察线速度对金刚石线锯切割过程的影响,研究了不同线速度条件下金刚石线锯的磨损情况以及硅片表面质量情况,通过SEM及粗糙度仪对切后线材、硅片等进行微观及量化分析。结果表明:线速度由1 300 m/min提高至1 800 m/min,金刚石线锯磨损量由3.5 μm逐渐降低到2.5 μm,降幅为28.6%;金刚石线锯切割硅材料为塑性及脆性模式混合去除,硅片表面的形貌呈现沟槽状、连续划痕并伴随大量凹坑;随着线速度的增加,硅片表面粗糙度逐渐减小,算数平均粗糙度R_a、最大高度R_z以及最大表面粗糙度R_t数值分别下降了33.7%、37.8%、45.6%,表面凹坑数量随着线速度的增大也逐渐减少。      

微细电火花加工的电极补偿方法研究

微细电火花加工中,电极损耗是引起加工误差的主要原因之一,因此必须进行电极的实时补偿以保证加工精度.研究了一种根据有效放电脉冲次数来进行实时补偿的方法,设计了基于可编程逻辑控制器(CPLD)的微细电火花补偿控制电路,并试验验证了此方法的可行性.