CUTTING REGULARITY AND DISCHARGE CHARACTERISTICS BY USING COMPOSITE COOLING LIQUID IN WIRE CUT ELECTRICAL DISCHARGE MACHINE WITH HIGH WIRE TRAVELING SPEED

The analysis of cutting regularity is provided through using and comparing two typical cooling liquids. It is proved that cutting regularity is greatly affected by cooling liquid＇s washing ability. Discharge characteristics and theoretic analysis between two electrodes are also discussed based on discharge waveform. By using composite cooling liquid which has strong washing ability, the efficiency in the first stable cutting phase has reached more than 200 mm^2/min, and the roughness of the surface has reached Ra〈0.8 μm after the fourth cutting with more than 50 mm^2/min average cutting efficiency. It is pointed out that cutting situation of the wire cut electrical discharge machine with high wire traveling speed （HSWEDM） is better than the wire cut electrical discharge machine with low wire traveling speed （LSWEDM） in the condition of improving the cooling liquid washing ability. The machining indices of HSWEDM will be increased remarkably by using the composite cooling liquid.

Analysis of Wire Vibration in Wire Electric Discharge Machining Process

Wire electric discharge machining(WEDM)process is used for precision manufacturing.The accuracy of machining is function of various parameters like current,voltage,wire speed,gap between wire and work piece,wire oscillation,work material,wire material,etc.Once the process parameters are selected,it is important that the wire vibrations are less to obtain a good surface finish.Due to the importance of wire vibration in obtaining the surface finish,it is necessary to study the wire vibration.This paper discusses different models of wire vibration presented in the literature and simulates a closed form solution of wire vibration using MATLAB.The transverse vibration of wire is analysed as forced vibration of moving wire with excitation due to the sparks during machining.The resulting partial differential equation is solved by using finite difference method and vibration is also simulated in the finite element package‘ANSYS’.The wire behaviour is investigated under different operating conditions and results of the two methods are

Development of micro wire electrical discharge machining platform and its application

A machining platform of micro wire electrical discharge machining (MWEDM) was developed. The key technology of MWEDM mainly includes granite basement, micro energy pulse generator, detection and servo control system, constant tension winding system and V-block guide wire mechanism. Utilizing micro wire electrode with 30μm in diameter, the MWEDM can machine the micro slot with the minimum size of 38μm wide, and the surface roughness is smaller than 0.1μm, the machining precision is less than 0.5μm, the white layer is no more than 2μm with main cut. All kinds of complex micro parts, such as micro gear, micro bearing bracket and micro shaped holes, can also be machined by using this platform.

Wire electric discharge machining characteristics of titanium nickel shape memory alloy

Ti Ni shape memory alloys（SMAs） have been normally used as the competent elements in large part of the industries due to outstanding properties, such as super elasticity and shape memory effects. However, traditional machining of SMAs is quite complex due to these properties. Hence, the wire electric discharge machining（WEDM） characteristics of Ti Ni SMA was studied. The experiments were planned as per L27 orthogonal array to minimize the experiments, each experiment was performed under different conditions of pulse duration, pulse off time, servo voltage, flushing pressure and wire speed. A multi-response optimization method using Taguchi design with utility concept has been proposed for simultaneous optimization. The analysis of means（ANOM） and analysis of variance（ANOVA） on signal to noise（S/N） ratio were performed for determining the optimal parameter levels. Taguchi analysis reveals that a combination of 1 μs pulse duration, 3.8 μs pulse off time, 40 V servo voltage, 1.8×105 Pa flushing pressure and 8 m/min wire speed is beneficial for simultaneously maximizing the material removal rate（MRR） and minimizing the surface roughness. The optimization results of WEDM of Ti Ni SMA also indicate that pulse duration significantly affects the material removal rate and surface roughness. The discharged craters, micro cracks and recast layer were observed on the machined surface at large pulse duration.

An experimental investigation of wire electrical discharge machining of hot-pressed boron carbide

The present work discusses the experimental study on wire-cut electric discharge machining of hot-pressed boron carbide.The effects of machining parameters,such as pulse on time(TON),peak current(IP),flushing pressure(FP) and spark voltage on material removal rate(MRR)and surface roughness(R_a) of the material,have been evaluated.These parameters are found to have an effect on the surface integrity of boron carbide machined samples.Wear rate of brass wire increases with rise in input energy in machining of hot-pressed boron carbide.The surfaces of machined samples were examined using scanning electron microscopy(SEM).The influence of machining parameters on mechanism of MRR and R_a was described.It was demonstrated that higher TON and peak current deteriorate the surface finish of boron carbide samples and result in the formation of large craters,debris and micro cracks.The generation of spherical particles was noticed and it was attributed to surface tension of molten material.Macro-ridges were also observed on the surface due to protrusion of molten material at higher discharge energy levels.

Electrical discharge machining of 6061 aluminium alloy

The wire electrical discharge machining（EDM） of 6061 aluminium alloy in terms of material removal rate,kerf/slit width,surface finish and wear of electrode wire for different pulse on time and wire tension was studied.Eight experiments were carried out in a wire EDM machine by varying pulse on time and wire tension.It is found that the material removal rate increases with the increase of pulse on time though the wire tension does not affect the material removal rate.It seems that the higher wire tension facilitates steady machining process,which generates low wear in wire electrode and better surface finish.The surface roughness does not change notably with the variation of pulse on time.The appearance of the machined surfaces is very similar under all the machining conditions.The machined surface contains solidified molten material,splash of materials and blisters.The increase of the pulse on time increases the wear of wire electrode due to the increase of heat input.The wear of wire electrode generates tapered slot which has higher kerf width at top side than that at bottom side.The higher electrode wear introduces higher taper.

Evaluation and analysis of cutting speed, wire wear ratio, and dimensional deviation of wire electric discharge machining of super alloy Udimet-L605 using support vector machine and grey relational analysis

The current study investigates the behavior of wire electric discharge machining （WEDM） of the super alloy Udimet-L605 by employing sophisticated machine learning approaches. The experimental work was designed on the basis of the Taguchi orthogonal L27 array, consid- ering six explanatory variables and evaluating their influ- ences on the cutting speed, wire wear ratio （WWR）, and dimensional deviation （DD）. A support vector machine （SVM） algorithm using a normalized poly-kernel and a radial-basis flow kernel is recommended for modeling the wire electric discharge machining process. The grey rela- tional analysis （GRA） approach was utilized to obtain the optimal combination of process variables simultaneously, providing the desirable outcome for the cutting speed, WWR, and DD. Scanning electron microscope and energy dispersive X-ray analyses of the samples were performed for the confirmation of the results. An SVM based on the radial-basis kernel model dominated the normalized poly- kernel model. The optimal combination of process vari- ables for a mutually desirable outcome for the cutting speed, WWR, and DD was determined as Ton1, Toffa, Ip1, WT3, SV1, and WF3. The pulse-on time is the significant variable influencing the cutting speed, WWR, and DD. The largest percentage of copper （8.66%） was observed at the highest cutting speed setting 7.05% of copper at the low of the machine compared to cutting speed setting of the machine.

RULED SURFACE MACHINING BY 4-AXES SIMULTANEOUS CONTROL WIRE-EDM

On the tasis of study in the mathematical model of 3-dimensional ruled surface (RS),this paper introduces a new concept of distance paramcter (DP) and also puts forward that themethod of modeling a RS depends on not only two boundary curves but also DP. According toabove theory, the formulas to calculate corresponding point coordinates to any kind of top and bot-tom profile of a workpiece and formulas to calcuate the maximum inclination angle of ruling linehave been obtained. Then a different top and bottom RS mathining method including profile withline-are combination as well as parametric curves has been achieved by 4-axes simultancous con-trol programming proposed.

Review on non-conventional machining of shape memory alloys

Shape memory alloys （SMAs） are the developing advanced materials due to their versatile specific properties such as pseudoelasticity, shape memory effect （SME）, biocompatibility, high specific strength, high corrosion resistance, high wear resistance and high anti-fatigue property. Therefore, the SMAs are used in many applications such as aerospace, medical and automobile. However, the conventional machining of SMAs causes serious tool wear, time consuming and less dimensional deformity due to severe strain hardening and pseudoelasticity. These materials can be machined using non-conventional methods such as laser machining, water jet machining （WJM） and electrochemical machining （ECM）, but these processes are limited to complexity and mechanical properties of the component. Electrical discharge machining （EDM） and wire EDM （WEDM） show high capability to machine SMAs of complex shapes with precise dimensions. The aim of this work is to present the consolidated references on the machining of SMAs using EDM and WEDM and subsequently identify the research gaps. In support to these research gaps, this work has also evolved the future research directions.

Electrical Discharge Machining of Al2024-65 vol%SiC Composites

In the present work, the wire electrical discharge machining（WEDM） process of the 65 vol% SiCp/2024 Al composite prepared by pressure infiltration methods has been investigated. The microstructure of the machined composite was characterized by scanning electron microscope, the average surface roughness（Ra）, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy（TEM） techniques. Three zones from the surface to the interior（melting zone, heat affected zone and un-affected zone） were found in the machined composites, while the face of SiC particles on the surface toward the outside was ‘‘cut＇＇ to be flat. Increase in Al and Si but decrease in C and O were observed in the core areas of the removed particles. Si phase, which was generated due to the decomposition of SiC, was detected after the WEDM process. The irregular and spherical particles were further observed by TEM. Based on the microstructure observation, it is suggested that the machining mechanism of 65 vol% SiCp/2024 Al composite was the combination of the melting of Al matrix and the decomposition of SiC particles.

MS-WEDM工作液智能控制系统装置研制

根据高速走丝电火花线切割机床(具有多次切割功能)的加工特点,研制工作液智能控制系统装置。该装置由STC89C52RC单片机、工作液电导率信号采集器、电磁阀和继电器等组成。阐述了控制装置的结构与功能、硬件控制方案、机床信号转换电路和报警电路等。该装置可直接安装在现有的高速走丝电火花线切割机床上,通用性好,且控制可靠性高,能够满足高速走丝电火花线切割机床对工作液智能控制的要求。

0.22 THz折叠波导慢波结构微细WEDM加工技术

0.22 THz折叠波导慢波结构具有尺寸小,刚度低,精确度与表面光洁度要求高,结构复杂的特点。若采用微数控铣削加工方式,加工产生的应力易造成零件变形。微细电火花线切割加工技术为无刚性电蚀加工,非常适合慢波结构的微细加工。本文从微能脉冲电源、微细电极丝、表面质量、表面残余应力等方面,介绍了0.22 THz折叠波导慢波结构微电火花线切割加工技术,实践证明:采用微电火花线切割加工工艺加工出的0.22 THz折叠波导慢波结构,经测试满足了设计要求。

基于正交试验的MS-WEDM第二次切割工艺参数优化

研究MS-WEDM多次切割中第二次切割参数对表面质量和切割速度的影响规律,寻求最优参数组合,有利于提高多次切割的加工质量。采用单因素试验研究第二次切割参数的脉宽、脉间、功放、丝速等参数对表面粗糙度和切割速度的影响规律,选取4水平4因素进行正交试验,用综合评分法将表面粗糙度和切割速度的多目标优化问题转化为加权综合评分的单目标问题。结果表明:更优的加工参数方案为脉冲宽度6μs、脉冲间隔5μs、功放1个、丝速6 m/s,并通过试验验证,其表面粗糙度为1. 54μm,切割速度为149. 43 mm^2/min,加权综合评分为0. 26。

低速WEDM制备的微织构螺旋微铣刀的铣削实验研究

基于五轴低速走丝电火花线切割机床与回转机构相结合的加工方法,制备了后刀面具有微织构的螺旋微铣刀.建立了微织构螺旋微铣刀微刃单元的切削力理论模型,并开展微织构微铣刀与常规微铣刀的对比实验研究.结果表明:微织构螺旋微铣刀的切削力相对于常规刀具降低了30%~40%,相同加工条件下,微织构螺旋微铣刀所加工的表面粗糙度降低至0.745μm,而常规微铣刀所加工的表面粗糙度为1.130μm.

HSWEDM工作液电导率信号采集器的设计与实现

该文设计了高速走丝电火花线切割机床工作液电导率信号采集器。该电导率信号采集器由驱动电压发生电路、电导率电极接线电路、变量程电路、信号放大调理电路、A／D转换电路、温度传感器电路和单片机组成。为了避免极化现象．且防止“漏电压”的干扰作用下信号产生畸变，电导驱动为电压±5V，频率1000Hz的方波。经测试，工作液电导率在2000-15000μS／cm的范围内与信号电压有较好的线性度，“漏电压”对信号电压干扰影响较小。工作液电导率信号采集器工作可靠性高，满足使用要求。

WEDM oriented micro gear design and mesh simulation

For the design of gears manufactured with wire electrical discharge machining （WEDM） technology, determination of the primary gear parameters is discussed considering the characteristics of the machining method. Some constraint conditions on gear parameters are abnegated, which makes micro gear design more flexible. Based on gear mesh theory, the algorithm of generating gear tooth profiles is studied, which includes involute and non-involute curve segments. The phenomena of tooth profile interferences during gear mesh are analyzed, and a gear mesh simulation algorithm is designed. Based on ACIS, the WEDM oriented software for the design and mesh simulation of micro gears is developed, by which the modeling, mesh simulation and interference check can be implemented. An experiment is carried out to design and manufacture a pair of micro involute gears, and the proposed method is proved feasible.

FOUR-AXIS WIRE-EDM SIMULATION OF COMPLICATED MODELS

In the verification of wire electrical discharge machining （EDM）, the motion and the performance of the wire-EDM system are analyzed. The maximum inclining angle of the wire is calculated. The relevant judgment methods are used for the collision between the wire, the fixture, and the machining table. In the wire-EDM simulation, the generated solid model can he used to investigate programming results and to check the machining accuracy. The generation algorithm for the solid model in the simulation is solved based on Boolean operations. The wire swept volume for each cutting step is united to form the entire wire swept volume. Through Boolean subtraction between the stock model and the entire wire swept volume, the solid model in the wire-EDM simulation is generated. The method is also suitable for the wire path intersection occurred in cutting cone-shaped models. Finally, experiments are given to prove the method.

基于模糊神经网络的WEDM可靠度预计

为了准确预计电火花线切割机床(WEDM)的可靠度,建立基于自适应模糊神经网络的可靠度预计模型。该模型以平均无故障时间为输入,以可靠度为输出,通过神经网络自适应训练获得适合WEDM可靠度预计的平均无故障间隔时间隶属函数。仿真结果表明,该模型的预计精度较高,与应用神经网络的WEDM可靠度预计结果相比,提高了96.4%。

MS-WEDM工作液智能控制系统设计与实现

根据具有多次切割功能的高速走丝电火花线切割机床加工特点和其工作液智能控制装置,完成了工作液智能控制系统的结构设计。根据工作液智能控制流程和单片机STC89C58RD+的工作特点,运用C语言编写了各模块初始化程序、A/D转换程序、温度采集程序、串口屏显示程序、自动换挡程序及电磁阀控制程序等。经软、硬件调试,该控制软件能实现对MS-WEDM工作液智能控制系统的控制。

HS-WEDM加工工艺指标的主要影响因素及其控制

高速走丝电火花线切割机床是目前我国生产和使用的主要线切割机种。本文就笔者在教学实习、生产实践中总结的影响HS -WEDM加工工艺指标的一些主要因素及其相关控制进行了分析。