Дисертації з теми "Electric discharge wire cutting"

This thesis looks at the capabilities of cutting thin webs on Wire EDM machines that are difficult or impossible to machine using conventional methods. Covered is an investigation of how different material and web thickness affect the capability of machining thin-walled parts. Five different metals are used for the test; Aluminum 6061 T6, Yellow Brass SS360, 420 Stainless Steel, D2 unheat-treated tool steel 25-30 RC, and D2 heat-treated tool steel 60-65 RC. The small parts were cut to a 6mm (0.2362 inch) height with six different wall thicknesses: 0.30mm (0.0118 inch), 0.25mm (0.0098 inch), 0.20mm (0.0078 inch), 0.15mm (0.0059 inch), 0.10mm (0.0039 inch), and 0.05mm (0.0020 inch). A Sodick AQ325L Wire EDM machine was utilized for testing. The methods employed during the study include the following: • Machine settings and offsets were limited to the default setting selected from the Sodick AQ325L database. • Two different pre-test cuts were taken on the material to check for web bending during the cutting process. • Hardness was tested for comparison of the web heights. This thesis shows that bending increased as webs became thinner and that bending occurred toward the wire as the second side of the web was cut. Bending does affect the height of the web. Physical properties of materials also impacted the height of the web with the hardest material staying intact during the cutting process. This study shows that two factors, physical properties of materials and web thickness, significantly affect cutting results for thin web parts.

This thesis deals with technology of electric discharge machining with emphasis on application of the principle of material removal on wire cut electric discharge machine. The main part is concentrated on wire cut electric discharge machining in terms of a small tool making shop. The goal of the thesis is to create a wire cut electric discharge machining workplace in the company with a focus on the production of cutting tools. The thesis defines requirements for each component of cutting tools and strategies for their machining. Machining of model part and subsequent technical - economic evaluation is included in the final part.

This marter’s thesis deals with the technology of electrical discharge wire cutting. There is described the basic nature of the electrical erosion, EDM principle and WEDM principle. The main part deals with the application of wire cutting in the manufacture pulley 68-8M-130 with a description of technology on the wire cutter Excetek V 650. At the end of the work is devoted to the statistical evaluation of the precision machined surfaces.

This master’s thesis familiarizes reader with technology of machine grinding – it’s history, principle, general use, related tools, achievable parameters and kinematics of grinding process. The core of work is analysis of jig-grinder Hauser H45-400, it’s kinematics, machine technical data, options and accessories. Work concludes with technical and economical assessment of machining of several parts with this machine and compares results to alternative options of machining.

Thesis (MScEng) -- Stellenbosch University, 2003.
ENGLISH ABSTRACT: High Speed Cutting (HSC), specifically milling is a significant contemporary development in machining. The Die and Mould industry is experiencing a difficult business climate. There is competitive pressure for shorter lead times and lower prices. Companies worldwide, are under financial pressure, to meet the challenges of a globalised business environment. The conventional position of milling and Electric Discharge Machining (EDM / Erosion) is discussed with the proposal to use HSC and EDM as complementary processes. Among new developments the progress in computer infrastructure is prominent. There is also a paradigm shift that should be made from experience based process planning to modern, up to date knowledge based process planning. High Speed Cutting is now a mature process capable of acceptable process security. The examples detailed include crankshaft-forging tooling, injection moulding tooling and powder sintering tooling. A process chain is proposed for the complementary HSC / EDM process with estimated illustrative time saving over the conventional EDM dominated process. HSC will be the first process removing the bulk of the material, finishing as far as possible and with EDM finally machining the features that will be difficult or impossible with HSC. To facilitate the use of the complementary processes a decision model to determine the crossover point between HSC and EDM is proposed. The decision model is firstly presented as a flow diagram to determine whether the task is a candidate for HSC only, EDM only, or the complementary HSC / EDM process. The key parameters e.g tool H d ratio are variables. This is in order that the flow diagram may be adapted to a specific machine tool infrastructure and expertise level in a company. The second part is a HSC machining time estimation model. The time is estimated per segment roughed, semi-finished, or finish machined. The model is in an empirical form with constants that can be adapted to the practices of a specific company. It is intended that the constants also be periodically revised to reflect the development in HSC expertise that will occur during the use HSC in the company. The model is practically evaluated with a case study, including the detail steps, not included in the model. Conceptual guidelines are given for software implementation. It is concluded that HSC and EDM are suitable complementary processes. It is a necessary prerequisite to use pallets to avoid multiple set-ups. Complementary HSC and EDM is especially appropriate for the gradual deployment and skill development for HSC. HSC and complementary HSC / EDM is considered the opportunity for companies to make a major breakthrough in lead time and operating expense if the necessary pallet/fixturing equipment, CAx infrastructure and human capability is available.
AFRIKAANSE OPSOMMING: Hoe Spoed Masjinering (HSC), spesifiek frees is ‘n betekenisvolle ontwikkeling in masjinering. Die Gereedskap en Gietvorm bedryf ervaar ‘n moelike besigheidsklimaat. Daar is kompeterende druk vir korter lewertye en laer pryse. Maatskappye wereldwyd is onder finansiele druk om in die geglobaliseerde besigheidsmilieu te presteer. Die posisie van frees en Elektriese Ontladingsmasjinering (EDM / Vonkerosie) word bespreek met die voorstel om HSC en EDM as komplementere prosesse te gebruik. Onder die nuwe ontwikkelings is daar prominente vooruitgang in rekenaarinfrastruktuur. Daar is ook ‘n paradigmaverskuiwing nodig van ondervinding gebaseerde na op datum kennis gebaseerde proses beplanning. HSC is nou ‘n ontwikkelde proses met voldoende prosessekerheid. Die voorbeelde sluit krukas smee gereedskap, inspuitgiet gereedskap, en poeier-sinter persgereedskap in. ‘n Prosesketting word voorgestel vir die komplementere HSC / EDM proses met ‘n beraamde illustratiewe tydbesparing oor die konvensionele EDM gedomineerde proses. HSC sal die eerste proses wees wat die meerderheid van die materiaal verwyder en oppervlaktes so ver as moontlik afwerk, met EDM wat die finale afwerking doen en ook die masjinering wat vir moeilik haalbaar of onmoontlik is vir HSC. Om die gebruik van die komplementere prosesse te fasiliteer, word ‘n beluitnemingsmodel vir die oorgangspunt tussen HSC en EDM voorgestel. Dit word eerstens as vloeidiagram gebruik om die taak te klassifiseer vir HSC alleen, EDM alleen of vir komplementere HSC en EDM. Die sleutelparameters, bv die beitel 116 verhouding, is veranderlikes. Dit is sodat die vloeidiagram aangepas kan word by ‘n spesifieke masjienvermoe en ‘n kundigheidsvlak in ‘n maatskappy. Die tweede deel is ‘n HSC masjineringstyd model. Die tyd word beraam per segment uitgerof, afgewerk, of finaal afgewerk. Die model is in empiriese vorm met konstantes wat kan aangepas word by die praktyke van ‘n firma. Dit is die bedoeling dat die konstantes periodiek aangepas word om die ontwikkeling te weerspieel wat in die maatskappy plaasvind. Die model word prakties evalueer met ‘n gevallestudie, insluitend die detailstappe, wat nie in die modelformulering ingesluit is nie. Konseptuele riglyne word gegee vir programmatuur implementering. Die gevolgtrekking word gemaak dat HSC en EDM geskikte komplementere prosesse is. Dit is ‘n voorvereiste om pallette te gebruik om veelvuldige opstellings te vermy. Komplementere HSC / EDM is veral toepaslik om HSC geleidelik in ‘n firma te ontplooi en kundigheid te bou. Die HSC / EDM kombinasie word ook die geleentheid geag vir firmas om ‘n deurbraak te maak in lewertyd en bedryfsuitgawes as die nodige pallettoerusting, CAx infrastruktuur en menslike vermoe beskikbaar is.

This work deals with analysis of EDM wire cutting technology and aims to assess the current situation and the real possibilities of EDM wire cutting usage in a small engineering company. Furthermore, it addresses manufacturing technology of a model component and the subsequent economic evaluation.

碩士
大葉大學
機械工程研究所碩士班
94
This study establishes the self-tuning opereation parameters and gap controller in opening architecture type computer numerical controller (CNC). A setp-wise changed operation paramers will be performed from the data base in CNC, in order to reach an appropriate dimention allowance. The reference input of the gap control system will also changed according to accual metal removeal rate. The experimental results show precision of corner cutting comparatively will the results of motion hold at corner in one second.

碩士
大葉大學
機械工程研究所碩士班
93
The main purpose of this study is to develop the open architecture CNC system of Wire-cutting EDM. The man-maching interface，part program in macro module，machine logioc control and operation parameters transfer are all built in the controller. A gap controller is also build via the lade diagram. Which can main fain a gap between the workpiece and the wire. The discharge can occur along the desired trajectory. The developed controller is equipped on a practical WEDM. The linear 、circular、and mult-shaper are machine by practical WEDM in order to conform the function on CNC.

碩士
國立中正大學
機械工程學系
85
The purpose of this thesis is two folds. First, it investigatesthe geometrical error of cutting corner under different setting parameters in wire-cut electrical discharge machine developed by the Mechanical Industry Research Laboratories of Industrial Technology Research Institute, Taiwan. It then proposes a strategy of controlling the wire-cut electrical discharge machine for minimizing any bluntness of an angular corner cut in a workpiece under optimum setting parameters for various cutting conditions. The geometrical errors of cutting corner under different setting parameters are determined by the Experimental Plan of Taguchi Quality Design. Based on the analysis of variance, the significant parameters affecting geometrical error of cutting corner are found. By means of regression analysis and the systematic machining test, the mathematical model and rule table related the significant parameters and the others are established. According to the developed mathematical model and rule table, a strategy to tune the machining parameters automatically at corner cut is constructed. Experimental results demonstrate that the strategycan improve corner accuracy.

碩士
國立中央大學
機械工程研究所
97
During solar cell processing, wafer cutting is an import procedure for yield, nowadays wire saw is the main cutting process, it has multi-wire with high efficiency, but has produced stress while cutting, it may let wafer break, and the particle can not be used fully, the particle will contaminate environment. Therefore, wire electrical discharge machining was investigated to improve wire saw processing, but most of research of material is single-crystal silicon, the poly-crystal investigate is few, because poly-crystal silicon with higher resistance, it is hard to machine for wire electrical discharge machining. This research is mainly divided into two major parts, the first part adopts pure water as dielectric in order to know the possibly of machinine, and investigate the influence of characteristic of each processing parameter The second part is according to the previous part results to improve the machining efficiency, we add sodium pyrophosphate powder in pure water, we want use phosphorous’ high electric conductivity to improve the efficiency, and use high temperature let phosphorous doping into wafer’s surface by wire electrical discharge machining to achieve p-n junction. Comparing with conventional solar cell processing, can save ion implantation, let the processing simply. Form the experiment results, using sodium pyrophosphate as dielectric can get fast feed ratio is 0.528 mm per second while pulse on time is 6.5μs, ampere is 10A, and comparing in the same parameter, the feed ratio increase 2.4 magnification, and improve surface roughness by electrolysis at high temperature, as previous results corroborating that dielectric with phosphorous can improve machining efficiency and dopping phosphorous into surface simultaneously.

碩士
國立中央大學
機械工程研究所
98
During solar cell processing, wafer cutting is an import procedure for yield, nowadays wire saw is the main cutting process, it has multi-wire with high efficiency, but has produced stress while cutting, it may let wafer break, and the particle can not be used fully, the particle will contaminate environment. Therefore, wire electrical discharge machining was investigated to improve wire saw processing, but most of research of material is single-crystal silicon, the poly-crystal investigate is few, because poly-crystal silicon with higher resistance, it is hard to machine for wire electrical discharge machining. This study is divided into two major parts, the first part of the pre-test to sodium pyrophosphate solution as dielectric, the Mole concentration 0.05M, adding different amounts of phosphoric acid to explore the feasibility of processing, the experiment with the different parameters and to understand the effect of processing characteristics of the trend. The second part o use the Taguchi method for processing the surface of phosphorus content on the processing with different parameters. The experimental results indicate that the best combination of process parameters, the Mole concentration of sodium pyrophosphate 0.025M, phosphoric acid than 1000:15, processing current 1.2A, pulse time 6μs and resting time 9μs. Detected by EDS, you can get the best surface phosphorus content 0.67wt%. By Mapping and Line scanning analysis confirm the processing of phosphoric acid added to sodium pyrophosphate solution can improve the processing of phosphorus content in the surface and inhibits the infiltration of impurities, while the effect of doping the surface can be obtained.

碩士
中華科技大學
機電光工程研究所在職專班
99
The copper wire poles used in ordinary electric discharge machines are non-rigid body, wherein force exerted between positive and negative pole, the length of time between each cutting voltage pulse and the change of gap between electrode and the working substrate, or water pressure from coolant, all will affect cutting speed. The purpose of this thesis is, then, to discuss the optimization of the parameters which can enhance the cutting velocity through Taguchi method. Based on Taguchi quality design experiment, use the standard aluminum sheet thickness of 10mm processing 6 mm round hole and examining the different combination of fabrication parameters on sheet metals in different angles. Once the optimum fabrication parameters be found, then the same set of the parameters can be applied to the different fabrication conditions.

碩士
國立臺灣大學
機械工程學研究所
93
The time consuming and tedious wire threading in Wire Electrical Discharge Machining (WEDM) before the start of the operation is always needed. In addition, wire breaking is inevitable during the machining process, and the chance to re-thread the wire is encountered from time to time. Hence the automatic wire feeder (AWF) is an essential unit closely related to machining efficiency and automation in WEDM. Despite various existing foreign and local patents, a new-type AWF based on modular design is developed in this thesis. Several units including wire receiving motor unit, wire cutting and shaping mechanism, motor positioning unit, etc. which have patent potential are proposed. The incorporation of special design cutter with electrical discharging for wire disconnecting while at the same time applying an appropriate tension on the wire during the wire disconnecting process results in very satisfactory profile wire. Besides, the disconnection point along the wire can be precisely controlled. The problem of too long and fine wire at the tip by using the heating and pulling strategy is prevented. The FEM is applied to simulate the fluid flow field and velocity within the pipe so that the proper shape of the wire guiding pipe can be determined. The developed system has less mechanical parts as compared to those of the existing systems. Hence, it is expected to be cost effective and easy for maintenance. In addition, the developed system is flexible, and it can be implemented on various wire-cut electrical discharge machine (Wire-cut EDM). The programmable logic controller (PLC) is taken for sequence control of the threading process. The associated software is written by the use of assembly language. Experiments are conducted to verify the threading performance of the developed system. It is found that the success rate is 84% ~ 96% for the 50~100 mm thickness workpiece having a 1mm in diameter initial hole. It is 79% ~ 91% when wire threading is carried out at the position of wire breaking. It is reduced to 76% ~ 86% when there is no workpiece in between the upper and lower wire guides. This performance is more or less comparable to the existing AWF. In conclusion, the AWF is successfully developed, and contribution to local EDM industry is expected.

碩士
國立成功大學
機械工程研究所
82
Traditionally, the work of taper-cut by a Wire-Cut Elec- tric Discharge Machine (WEDM) is to drive the upper guide along U-V axes to conduct the inclination of the wire by means of the relative movement between the upper and the lower guides. Since the guide can only move along U-V axes rigidly when executing the taper-cut work, it usually induces problem such as increment of wire friction, unstable of wire tension, insufficiency of cutting fluid spray, and breaking of wire,... etc. Consequently, it can only work on small angles and thin materials. Here, We apply the motions of mechanisms to conduct the upper and the lower guides to provide both the relative translation and the slop angle. This provides a fundamental and effective way to operate the taper-cut, and eliminates the disadvantages of the traditional approach. Based on the location of the rotational center, the relative movement of the upper and the lower guides, can be classified into four types. And, we use the type with the rotational center location at the lower guide as a design requi- rement. Since the taper-cut mechanism must move the upper guide to do translation and rotation and move the lower guide to do rotation, the guide must have two points of action to do the same movement. Based on the fact that the distance between two points can be variable or fixed, we have four cases for the ge- nerations of design concepts. As a result, we present some de- sign concepts for the taper-cut mechanisms including Pantograph Mechanism, Duplex Parallel-Crank Mechanism, Fixed-Type Four-Bar Mechanism. In conclusion, this work studies basic functions and design requirements of taper-cut mechanisms for WEDM, provides some design concepts, and performs their kinematic analysis. Furthermore, some concepts have the potential for patent gran- ting.

碩士
中州科技大學
機械與自動化工程系
106
The purpose of this study is to build machining data base of aluminum-metal matrix complex (AMMC), in order to replace traditional machining with non-traditional machining of EDWC. Three types of aluminum-metal matrix complexes were used to develop complex materials of the hardness via different contents of SiC percentage. Results showed that not only defects of materials casting plausibly was disadvantageous to mechanical properties of aluminum-metal matrix complexes but also led to wire-breakage as machining of EDWC. The effects of aluminum-metal matrix complexes on the characteristics of machinability of EDW as below: (1) With increasing on time of cutting conditions, the surface roughness of aluminum-metal matrix complexes increases. The EDW surface of aluminum-metal matrix complexes was rougher than that of as-cast A356.2 due to microstructure of SiC; (2) The factor's order of cutting feedrate for AMMC measured by simulated regression as followed: thickness of the workpiece, on time, feedrate override of the table, SiC contents; (3) In order to acquire the precision of workpieces by setting higher water flow rate, resistivity of dielectric fluid and wire tension prior to wire-breakage. The thickness and hardness distributions of remelted layer in cross-sectional area of EDW surface differed from that of EDM. The dimension of remelted layer of AMMC in cross-sectional area of EDW surface was not as the same as in terms of measuring instruments such as OM, Hv and SEM. Although there was the thinner distributions of AMMC than that of A356.2 due to microstructure of SiC changed the microstructure of remelted layer and mechanical properties.

碩士
雲林科技大學
機械工程系碩士班
98
In this study, it is practiced with electric discharge coating (EDC), in the alignment mechanism of spiral way, around the whole circumference of tungsten wire. The multi-layer composite electrode is composed of titanium and graphite, stacked alternatively, tungsten wire is taken as the workpiece, in the process of the electric discharge, the electrode and the workpiece are both fused and they solidify on the surface of the workpiece, forming the coating of titanium carbide. Taguchi’s L9 orthogonal array is applied in the experiment to acquire the effects of the process parameters on the coating and then the better arrangement of the parameters is set, the experimental parameters are set as the discharge current (IP), the pulse on time (τon), the pulse off time (τoff), the volume of a single reaming (△R), the wire move seed (Vwire) and the types of different structure of electrode (Type1、2、3). The results of the experiment, on the uniformity, the hardness, the component, the thickness, the tensile test and the microscopic observation of the surface of coated layer, are analyzed and discussed. The experimental results indicate that graphite electrode may enhance surface hardness of the coated layer, increase the content of TiC, enhance the distribution of film thickness uniformity and continuity, and enhance the stability of electric discharge and coating speed.

In India, with the increase in the number of industries and vehicles the environment is getting more and more polluted. More than industries it is the rapid growth of vehicles which causes serious environmental crisis in the form of air pollution and has become alarming particularly in cities. The industrial and vehicular growth cannot be neglected, as the country’s economic and social well being is largely dependent on them. But this should not come at the cost of our health and eco system. The industrial and vehicular emissions must be controlled in order to keep our air clean. Continued efforts in this direction are being taken up across the globe to investigate an efficient and economical technique. There are many air pollutants being emitted from both natural and manmade sources. The major air pollutants identified as hazardous to human health are nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), volatile organic compounds (VOC), and sulfur dioxides (SOx). Among these, nitrogen oxides are considered to be difficult to remove. The sources of NOx are thermal power plants, stationary and mobile diesel engines, gasturbine engine, ironore sintering plants and various other smallscale utilities. There are conventionally available technologies to remove NOx such as chemical scrubbing, catalysis etc. But these techniques are either difficult to operate or do not bring down the level of NOx to the required norms imposed by the government. The failure of conventional techniques to remove NOx to the expected limit led to the development of alternative nonconventional techniques. Prominent among these new alternative techniques is electric discharge plasma, where the gas is partially ionized and temperature of electrons is considerably higher than that of ions and background gas molecules. Diesel engines are getting popular due to their inherent merits and their number is increasing considerably. Unfortunately, the exhaust of diesel engine being complex with high oxygen content makes the existing pollution control techniques insufficient particularly with regard to removal of NOx. So there is a need for investigating better technology which can effectively abate the pollutants from diesel engine exhaust. Electric Discharge plasma is one such alternative technique which has been very successful in large volumes of flue gas cleaning and hence, its potential is being explored in the cleaning of small volumes of vehicular exhausts, in particular, diesel engine exhaust. In the present work we investigated the relative performance of different electric discharge plasma reactors, with different type of voltages like AC, DC and pulse. The reactors were evaluated for NOx removal efficiency and NO conversion. This research work is a feasibility study to find whether electric discharge plasma can be used more effectively as an alternative technology for the after treatment of diesel engine exhaust in cascade with some cheaper adsorbents, if necessary. The scope of this qualitative experimental study can briefly be summarized as below: . • To study different reactors for NO conversion and NOx removal . • To study the effect of dielectric pellets in enhancing the radical production which in turn will have a bearing on the chemical reactions . • To study the effect of different types of voltages on the cleansing process . • To propose an efficient reactor system subject to the experimental conditions studied.