基于表面质量分析的聚晶金刚石刀具电火花放电磨削试验研究

以2、10μm两种粒度的聚晶金刚石作为研究对象,以工艺试验结合材料学测试作为分析手段,简单对比了盘状电极和线电极加工的表面质量,研究了金刚石粒度、电极极性、电极转速对精密电火花放电磨削聚晶金刚石的表面质量和材料去除率的影响.结果表明:采用负极性加工时,加工表面未出现多孔结构,表面质量好,放电蚀除无选择性;随着电极旋转线速度增加,聚晶金刚石材料的去除量也逐步增加,聚晶金刚石材料的表面粗糙度值先减少后增加;在电极线速度达80 m/min时,聚晶金刚石样件表面粗糙度值达到最小值,聚晶金刚石材料的去除量也趋于稳定.     

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。     

大面积聚晶金刚石复合片电火花加工温度场及应力场的数值模拟

在研究电火花加工机理的基础上,基于有限元原理,建立了电火花连续脉冲放电磨削聚晶金刚石复合片时的物理模型,对磨削过程工件表面的温度场、应力场分布及工件材料的变形规律进行了模拟分析.研究了脉冲宽度及峰值电流对温度场、应力场分布及复合片变形量的影响规律.结果表明,有限元法是分析大面积聚晶金刚石复合片电火花磨削过程中温度场、应力场及变形的一种有效方法,其计算结果可用来指导制定合理的加工工艺参数以提高加工质量和加工效率.     

PZT激励同步压缩放电通道微细电火花加工工艺参数对加工结果的影响

提出了压电陶瓷(piezoelectric ceramic transducer,PZT)激励同步压缩放电通道微细电火花加工,目的在于改善微细电火花加工的放电环境。介绍了PZT激励同步压缩放电通道微细电火花加工原理,研究了开路电压、脉冲宽度、脉冲频率和峰值电流对其电极损耗和材料去除率的影响,并与不采用压缩通道方法的微细电火花加工进行了对比。结果表明:同等条件下,采用PZT激励同步压缩放电通道技术,提高了加工过程的稳定性和材料去除率,降低了电极损耗率,有效改善了放电环境。     

电参数对钛合金放电诱导可控烧蚀车削加工的影响研究

设计了基于放电概率的诱导烧蚀电极伺服控制系统,通过优化实验,设定其放电概率为80%,并在此基础上分析了脉冲宽度、脉冲间隔、峰值电流等电参数对加工的影响。结果表明:正极性加工时,峰值电流对加工效率的影响最大。通过选取优化参数,与常规电火花车削对比表明:放电诱导可控烧蚀车削的材料加工效率是常规电火花车削的27倍,电极相对损耗仅为常规电火花车削的80%。     

碳化硅材料机械磨削辅助电火花加工的工具电极设计及试验研究

针对碳化硅材料的平面加工需求,提出了一种机械磨削辅助电火花加工的方法。通过设计组合式工具电极和搭建试验系统,采用去离子水冲液方式,在不同工艺参数(如峰值电压、峰值电流、脉宽、工具转速等)下,探索表面粗糙度与工具电极损耗的变化规律。试验结果表明:在相同电参数条件下,通过采用机械磨削辅助电火花加工方法,表面粗糙度值从Ra3.90μm降低到了Ra3.01μm,电极质量相对损耗减少了26.07%。     

BDXJ超硬材料电火花线切割机床产品简介

采用增加放电击穿爆炸力的方法对超硬材料(如:聚晶金刚石、聚晶立方氮化硼、碳化硼等)进行高效地加工的新技术,无疑是电火花加工的一个新发展。这项技术,84年获国家发明二等奖,85     

聚晶金刚石电火花磨削试验的人工神经网络建模

聚晶金刚石(PCD)由于具有高硬度、高耐磨性和抗腐蚀性等优良的特性,其应用范围日益广泛,但是其成型加工非常困难。目前,聚晶金刚石常用的加工方法有机械研磨和电火花磨削,由于机械研磨效率低、金刚石层厚度不均匀等缺点,其应用受到很大限制。而电火花磨削工艺加工效率高,PCD平面度易于控制,近年来得到了迅速的发展。电火花磨削工艺主要参数如工件极性、脉冲宽度、脉冲间隔、峰值电压和峰值电流对工艺指标金刚石材料去除率(MRR)均有影响,而一般的方法难以确定工艺参数与工艺指标的关系,本文建立了电火花磨削参数和金刚石材料去除率的人工神经网络模型,该模型对未知工艺条件下的预测结果最大误差为14．29％,基本满足工程实际的需要。     

基于正交试验的电火花加工工艺效果试验分析

通过正交试验分析,探讨了电火花成形加工中影响加工效果的主要因素,分别阐述了脉冲峰值电流、脉冲宽度及脉冲间隔等对加工速度、加工表面粗糙度及工具电极损耗的影响关系,对解决电火花加工实践中工艺参数优化问题具有一定的理论指导意义.     

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.     

电火花铣削加工工艺与算法研究

介绍了电火花铣削加工工艺及其有关计算方法。在大量实验的基础上,研究了微细电火花分层铣削加工,采用电极底面放电方式、电极轨迹规划、电极的损耗及补偿策略和合理选择分层厚度及电极微进给量等关键技术,提高了加工精度和效率。     

微细电火花加工实现条件的研究

介绍了微细电火花加工的原理和特点,从加工表面质量、脉冲电源、微细工具电极的制造和安装、放电面积效应的影响、伺服控制系统等方面对微细电火花加工的实现条件进行了研究,并给出了微细轴的电火花加工等具体加工实例.研究结果对微细电火花加工技术的具体应用具有重要的参考价值和指导意义.     

气中连续放电辅助加工中的控制系统设计

以压电陶瓷微位移驱动原理为基础，对精密驱动技术在气中连续放电辅助加工控制系统中的应用进行了研究。设计了一个包括单片机、压电陶瓷驱动电源、信号检测及处理电路组成的气中连续放电辅助加工控制系统。该系统能根据加工时两电极间电压的变化自动寻找最佳放电间隙，并维持辅助加工中的连续放电,可应用于一些高硬度、难切削材料的辅助加工领域。     

Advancing EDM through Fundamental Insight into the Process

This paper aims to show the prospects of electrical discharge machining (EDM) technology by interrelating recent achievements in fundamental studies on EDM with newly developed advanced application technologies. Although gap phenomena in EDM are very complicated and hence not yet very well understood, recent improvements in computers and electronic measuring instruments are contributing to new discoveries and inventions in EDM technology. Such newly acquired insight sometimes raises questions on the validity of the established theories of EDM phenomena, and EDM processes once believed to be impossible or unrealistic are now becoming practical.     

Study of specific discharge energy in WEDM and its application

The relationship between machining parameters and machining characteristics of different materials in WEDM is difficult to obtain because a large number of experiments must be conducted repeatedly. A new concept attempting to solve this problem is presented in this paper. The specific discharge energy (SDE) defining as the real energy required to remove a unit volume of material is proposed. The SDE is constant for a specific material. Experimental results reveal that the relative relationship of SDE between different materials is invariant as long as all materials are machined under the same machining conditions. It is also found that the materials having close value of SDE demonstrate very similar machining characteristics such as machining speed, discharge frequency, groove width and surface finish of the machined surface under the same machining conditions. This result can be applied for the determination of the settings of machining parameters of different materials. Furthermore, by dimensional analysis of SDE, a quantitative relationship between machining characteristics such as the material removal rate and the efficiency of material removal and machining parameters is derived.     

Understanding behavior of machining interface and dielectric molecular medium in nanoscale electro-machining

Recently, a repeatable and scalable nanoscale electro-machining (nano-EM) process to produce sub-20 nm scale features has been demonstrated. In the presented research, the behavior of the liquid dielectric (n-decane) machining medium in nano-confinement (<3 nm) under physical boundary conditions is investigated using molecular dynamics (MD) simulation. Results show a four-fold increase in the density of n-decane indicating ‘quasi-solid’ behavior at the nano-EM interface, thereby acting as an effective charge transport medium between the nano-tool and the workpiece. The effect of such quasi-solid medium is demonstrated through the experimental observations of electrical breakdown (BD) at the sub-20 nm scale interface.     

用放电加工方法实现金属材料表面改性

对放电加工进行表面改性的基本原理、电极制备、表面涂层特性以及此方法的研究和应用前景进行了论述。     

大平面电火花磨削加工原理与设计

采用普通机械磨削方法加工大平面的硬脆材料,往往效率低、成本高。在分析电火花磨削加工特点的基础上,提出了大平面电火花磨削加工的原理,设计出相应的加工装置。经实验验证,该设计方案可行,加工效果较好。     

Material Formability and Coil Design in Electromagnetic Forming

Pulsed electromagnetic forming is based on high-voltage discharge of capacitors through a coil. An intense transient magnetic field is generated in the coil and through interaction with the metal work-piece; pressure in the form of a magnetic pulse is built up to do the work. Data on formability of two aluminum alloys employed for exterior (6111-T4) and interior (5754) automotive body panels will be shown. Comparison of traditional Forming Limit Diagrams obtained by stretching of aluminum sheet with hemispherical punch to the results on formability, where hemispherical punch is replaced by a coil will be provided. It will be shown that material formability in high-rate forming conditions can significantly depend upon interaction with the forming die: electromagnetic forming into an open round window provides only slight improvement in formability, while forming in a V-shape die or into a conical die indicates a significant improvement. An important part of the electromagnetic forming technology is the design of the coil. The coil failure modes and measures preventing them are discussed. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held October 15-19, 2006 in Cincinnati, OH.     

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.