快走丝线切割机床恒张力复合运丝机构研究

通过分析高速走丝电火花线切割机床的现状,提出了一种新型快走丝电火花线切割机床的恒张力复合运丝装置,并阐述了这种装置的结构和工作原理.     

电火花线切割Cr12MoV模具钢工艺规律的试验研究

电火花线切割技术在冲压模具的加工中具有重要作用。在中走丝电火花线切割机床上,以脉宽时间、脉间时间、加工电流以及运丝速度等工艺参数为变量进行切割Cr12MoV模具钢的单因素试验研究。结果表明,各工艺参数中,运丝速度对切割速度的影响程度最大,而相比于对切割速度的影响,各工艺参数对表面粗糙度的影响稍小。此外,当脉宽时间为20μs、脉间时间为40μs、加工电流为7档以及运丝速度为3档时,可以达到最大的切割速度99.01mm~2/min和较小的表面粗糙度值2.904μm。     

高铌钛铝合金中走丝电火花线切割加工工艺研究

为了研究高铌钛铝合金工件中走丝电火花线切割加工工艺,以脉冲宽度、放电跟踪间隙、运丝速度三个工艺因素为研究对象,基于在中走丝电火花线切割加工高铌钛铝合金工件试验,揭示三个工艺因素对加工效率、切缝宽度扩大量和表面质量的影响。     

电火花线切割机床工艺参数优化数据库系统

论述了电火花线切割机床加工过程中电源波形和电参数对工艺指标的影响，以及电极丝对工艺效果的影响，并分析了断丝原因。应用Visual FoxPro6.0建立了“电火花线切割机床工艺参数优化数据库系统”。     

第十二届中国国际机床展览会特种加工机床评述（下）

二、电火花线切割机床（WIRE-CUT）1.国外单向走丝电火花线切割机床国外单向走丝电火花线切割机床的技术发展水平,着重针对电火花线切割加工特点及应用情况,在脉冲电源、自动控制及主机结构等影响线切割加工三大指标的几个关键功能部件上有所创新,并且在实用性、稳定性、可靠性,以及各功能模块的自适应控制性能等方面有所提升（1）脉冲电源技术高效电火花脉冲电源是单向走丝线切割机床的核心单元,高频脉冲电源的自适应控制策略的优劣,对单向走丝线切割的加工效率、加工精度,     

快走丝电火花线切割大厚度工件的电参数设置研究

电参数的选择是快走丝电火花线切割大厚度工件的重要内容,通过对脉冲宽度、占空比、加工电流和进给速度采用控制单因素变量法进行切割实验,揭示了快走丝电火花线切割大厚度工件的电参数选择原则,脉宽时间和占空比应选择偏小,在保持稳定加工的前提下,加工了电流和进给速度选择偏大,以期为大厚度工件的快走丝电火花线切割提供工艺参考。     

基于DSP的线切割机床数控系统的研制

随着制造技术的日新月异和工业生产的迅猛发展,电火花线切割技术己成为机械制造领域中一种重要的加工技术,它是通过两电极间脉冲放电,用电蚀原理对工件进行加工。线切割加工具有无切削力,工件材料硬度对可加工性影响不大等优点,得到了广泛的应用。目前国外生产和使用的绝大多数为高速快走丝电火花线切割机床,而我国生产和使用的则主要为慢速单向走丝电火花线切割机床。两者相比,除了采用的工艺不同外,无论在精度、功能、自动化程度、可靠性、加工稳定性和加工工艺指标方面,还是在外观等方面,后者较前者线切割机床平均明显低一个档次。本文对电火花线切割机床进行了基于DSP的CNC控制器的基础开发。经过操作功能与加工实验的试验,试验结果显示本文所开发的基于DSP的CNC控制器能够实现电火花线切割机床的基本操作功能与实际放电加工,并且将国产的电火花线切割机床CNC控制器提高到多CPU、Windows操作系统与基于DSP电控系统新的发展框架上。     

基于正交试验和BP神经网络的Ti-6Al-4V合金电火花线切割工艺参数优化

针对切削性能差难以加工的Ti-6Al-4V合金进行了电火花线切割加工试验研究,运用正交试验的方法对工艺数据进行极差、方差分析,探究电火花线切割加工的规律和特性。重点分析脉冲宽度、脉冲间隔、功放管数和运丝速度等工艺参数对钛合金加工质量的影响,取得了线切割最优化参数组合。搭建了基于L-M优化算法的BP神经网络的线切割加工工艺网络预测模型,该模型训练速度快、预测精度高,可为Ti-6Al-4V合金的切割提供可靠的加工质量预测,对实际加工的参数选择具有一定的参考作用。     

电火花线切割加工工艺指标的影响因素及其改进措施的研究

电火花线切割机床对零件的加工精度(主要指加工的形状精度和位置精度)不仅与机床固有的结构设计精度和精度保持性有一定的直接关系,放电过程控制的好坏也直接影响到加工性能的优劣.阐述了电火花线切割的工艺指标,分析了电参数和非电参数等方面对工艺指标的影响,并针对这些因素提出了提高电火花线切割加工质量的有效方法及生产过程中的注意事项.     

电极丝横向振动对电火花线切割加工间隙影响规律研究

以提高电火花线切割加工效率为目的,分析了电火花线切割加工间隙对加工效率的影响,建立了电极丝横向振动数学模型,揭示了各工艺参数对电极丝振幅及加工间隙的影响规律。采用直径1mm的钼丝进行了加工实验,得到了峰值电流、脉冲宽度和脉冲频率等参数对电极丝振幅的影响规律。结果表明所建立的振动模型正确,可为优化电火花线切割加工间隙,从而提高其加工效率提供参考。     

Study on the Variations of Form and Position of the Wire Electrode in WEDM-HS

The electrode, a tool which is used for wire electrical discharge machining (WEDM), is a tiny flexible metal wire, therefore, in WEDM machining process, its form and position will inevitably vary because of the action of many forces, and these dynamic variations have a direct influence on machining precision and stability, especially in the high-speed WEDM (WEDM-HS) machine process; the variations of form and position have been a critical obstacle to improving machining quality and implementing multi-cut processing. In this paper, the variation regularity of wire-electrode has been investigated by experimental analysis, and some corresponding measures have been suggested to stabilize the form and position of the wire electrode in the WEDM-HS machining process.     

电火花线切割加工中线电极的动态特性仿真与实验研究

研究慢走丝电火花线切割加工中电极振动对加工状态的过程的影响。应用计算机仿真技术,分析连续放电力作用下线的振动模态以及对放电点转移和分布的作用。结果表明,加工工艺参数明显影响放电点的转移与分布,适当地选择工艺参数可获得最佳的放电分布率。该研究对提高慢走丝加工稳定性,防止断丝的发生提供了相应理论依据。     

Optimization of wire electrical discharge machining (WEDM) process parameters using Taguchi method

Wire electrical discharge machining (WEDM) is extensively used in machining of conductive materials when precision is of prime importance. Rough cutting operation in WEDM is treated as a challenging one because improvement of more than one machining performance measures viz. metal removal rate (MRR), surface finish (SF) and cutting width (kerf) are sought to obtain a precision work. Using Taguchi’s parameter design, significant machining parameters affecting the performance measures are identified as discharge current, pulse duration, pulse frequency, wire speed, wire tension, and dielectric flow. It has been observed that a combination of factors for optimization of each performance measure is different. In this study, the relationship between control factors and responses like MRR, SF and kerf are established by means of nonlinear regression analysis, resulting in a valid mathematical model. Finally, genetic algorithm, a popular evolutionary approach, is employed to optimize the wire electrical discharge machining process with multiple objectives. The study demonstrates that the WEDM process parameters can be adjusted to achieve better metal removal rate, surface finish and cutting width simultaneously.     

快走丝电火花线切割加工仿真系统

通过神经网络技术建立了快走丝电火花线切割加工工艺模型 ,利用穷举法建立了具有一定人工智能的工艺参数全局优化系统 ,开发了模具电火花加工过程仿真系统。该系统不仅可以精确预测加工效果 ,而且克服了工艺参数表的局限性 ,弥补了建立在工艺参数表基础上的参数自动选取系统的缺陷 ,实现了工艺参数全局最优化。测试结果及实际使用结果表明本文所建立的仿真系统反映了机床的加工工艺特性 ,预测误差基本控制在 8%内 ,系统的参数优化选取功能使机床的加工性能得以充分发挥。仿真系统具有广泛的通用性 ,可适用于不同类型的线切割加工机床。     

An experimental investigation on machining parameters of AISI D2 steel using WEDM

The performance of the wire electrodischarge machining (WEDM) machining process largely depends upon the selection of the appropriate machining variables. Optimization is one of the techniques used in manufacturing sectors to arrive for the best manufacturing conditions, which are essential for industries toward manufacturing of quality products at lowest cost. As there are many process variables involved in the WEDM machining process, it is difficult to choose a proper combination of these process variables in order to maximize material removal rate and to minimize tool wear and surface roughness. The objective of the this work is to investigate the effects of process variables like pulse on time, pulse off time, peak current, servo voltage, and wire feed on material removal rate (MRR), surface roughness (SR), gap voltage, gap current, and cutting rate in the WEDM machining process. The experiment has been done using Taguchi’s orthogonal array L27 (3⁵). Each experiment was conducted under different conditions of input parameters and statistically evaluated the experimental data by analysis of variance (ANOVA) using MINITAB and Design Expert tools. The present work also aims to develop mathematical models for correlating the inter-relationships of various WEDM machining parameters and performance parameters of machining on AISI D2 steel material using response surface methodology (RSM).The significant machining parameters and the optimal combination levels of machining parameters associated with performance parameters were also drawn. The observed optimal process parameter settings based on composite desirability (61.4 %) are pulse on time 112.66 μs, pulse off time 45 μs, spark gap voltage 46.95 V, wire feed 2 mm/min, peak current of 99.99 A for achieving maximum MRR, gap current, gap voltage, cutting rate, and minimum SR; finally, the results were experimentally verified.     

Fabricating micromilling tool using wire electrodischarge grinding and focused ion beam sputtering

In the present research, wire electrical discharge machining (WEDM) of γ titanium aluminide is studied. Selection of optimum machining parameter combinations for obtaining higher cutting efficiency and accuracy is a challenging task in WEDM due to the presence of a large number of process variables and complicated stochastic process mechanisms. In general, no perfect combination exists that can simultaneously result in both the best cutting speed and the best surface finish quality. This paper presents an attempt to develop an appropriate machining strategy for a maximum process criteria yield. A feed-forward back-propagation neural network is developed to model the machining process. The three most important parameters – cutting speed, surface roughness and wire offset – have been considered as measures of the process performance. The model is capable of predicting the response parameters as a function of six different control parameters, i.e. pulse on time, pulse off time, peak current, wire tension, dielectric flow rate and servo reference voltage. Experimental results demonstrate that the machining model is suitable and the optimisation strategy satisfies practical requirements.     

A self-learning fuzzy controller for wire rupture prevention in WEDM

Wire breaking is a serious problem in the application of wire electrical discharge machining (WEDM). A WEDM sparking frequency monitoring and control system based on the characteristics of the voltage waveform of WEDM is developed. Two types of wire breaking phenomena are categorised according to the duration of the symptoms: a sudden rise of sparking frequency, and a sluggish rise of sparking frequency. Based on these results, a new self-learning fuzzy controller (SLFC) is proposed. The pulse off-time is regulated in real-time to keep the sparking frequency at a safe level so that wire breaking can be prevented. Experimental results show that this monitoring and control system can control the sparking frequency at an optimal high metal removal rate level without the risk of wire rupture.     

Surface crack density and recast layer thickness analysis in WEDM process through response surface methodology

In this work, quantitative assessment of surface damage in terms of parameters like surface crack density and recast layer thickness in wire electrical discharge machining (WEDM) process has been undertaken. The effect of processing conditions on crack formation is studied using scanning electron microscope. Surface crack density and recast layer thickness analysis in terms of machining parameters such as pulse on time, pulse off time, peak current, spark gap voltage significantly deteriorate the microstructure of machined samples, which produces the deeper, wider overlapping craters, pock marks, globules of debris and micro cracks. The microstructure analysis of WEDM surface was based upon the theory of electrical discharge phase and metallurgical physics. It is found that the pulse on time, pulse off time and peak current are the most dominating parameters for both surface crack density and recast layer thickness.     

Optimization of WEDM process of pure titanium with multiple performance characteristics using Taguchi’s DOE approach and utility concept

This paper describes the development of multi response optimization technique using utility method to predict and select the optimal setting of machining parameters in wire electro-discharge machining (WEDM) process. The experimental studies in WEDM process were conducted under varying experimental conditions of process parameters, such as pulse on time(T_on), pulse off time(T_off), peak current (IP), wire feed (WF), wire tension (WT) and servo voltage (SV) using pure titanium as work material. Experiments were planned using Taguchi’s L27 orthogonal array. Multi response optimization was performed for both cutting speed (CS) and surface roughness (SR) using utility concept to find out the optimal process parameter setting. The level of significance of the machining parameters for their effect on the CS and SR was determined by using analysis of variance (ANOVA). Finally, confirmation experiment was performed to validate the effectiveness of the proposed optimal condition.     

Self-tuning fuzzy control with a grey prediction for wire rupture prevention in WEDM

Wire rupture in the wire electrical discharge machining (WEDM) process is one of the most troublesome problems in practical applications. In this paper, the abnormal ratio R_ab, defined as the proportion of abnormal sparks in a sampling period, is taken to represent the gap state in machining. The grey predictor is adopted to compensate the time-delayed R_ab caused by the low pass filter data processing. A gain self-tuning fuzzy control system has been developed to cope with the conditions that often occur with wire rupture in the WEDM process, such as an improper setting of machining parameters, machining the workpiece with varying thickness, etc. Experimental results of several cases show that the proposed controller results in a satisfactory performance. Not only can it immediately suppress transient situation once there is a sudden change of workpiece thickness, but a stable performance can also be achieved during machining a workpiece of constant thickness. As a result, wire rupture problems in most WEDM processes can be successively solved by the proposed control strategy.