1. 研究目的与意义（文献综述包含参考文献）
Wire electrical discharge machining, also known as WEDM is a non-conventional machining process that use to cut the conductive material. WEDM is one kind of EDM process by uses a wire as an electrode and discharge when the workpiece gets close to generating electric sparks that can easily melt and evaporate the material to realize the cutting process [1]. This technology was invented by the former Soviet Union scholars Lazarenko and his wife in the year of 1943. The world's first wire cutting the machine was invented in the former Soviet Union in the year of 1960. The working principle of EDM is to use a constant pulse discharge between the tool electrode and the workpiece, and the metal is melted, oxidized, and corroded by high temperature, so it is also called electric erosion machining [2]. Due to its working principle, WEDM can easily cut through any conductive material, even hard or thick material. Therefore, WEDM is mostly used in the manufacture of molds and dies, particularly extrusion dies and blanking punches. The benefit of using WEDM in the machining process is WEDM process does not apply any impact on the workpiece while in the cutting process.On the other hand, WEDM also got the capability of machining complex and fine workpiece shapes due to a WEDM machine uses electrical discharges throughout a fine wire. As the result, WEDM is capable of easily cutting precise and complex shapes, even in the hardest or most fragile materials. Next, high tolerance is also one of the advantages of WEDM for using it in the machining process. Wire EDM machining is more precise than laser, flame cut, or plasma machining. This eliminates the need for additional post-machining processing and finishing of parts. Under certain conditions, the WEDM also can let the processing time become faster. For example, with experienced and efficient machining engineers, wire EDM projects can be set up and completed with shorter lead times, allowing the customer to get important parts faster. In addition, due to the high tolerance of WEDM, the workpiece in order to skips other processes to save more time and can allow the customer to get their product. Last but not least, the benefit of using WEDM in the machining process is the cost-effectiveness of the WEDM. This is because any electrically conductive material, no matter how hard or fragile, can be efficiently machined using wire EDM machining, machining takes less time and can be completed in a single process. As a result, wire EDM generates less waste. There is no need for heat treatment or post-machining cleaning because wire EDM can cut through even hardened materials with ease. Therefore, the cost of production of better dies and molds will be lowered by using WEDM to produce the dies and molds. These savings also allow processing companies to achieve more cost-effective processing.For the topic of my graduation project and thesis is research on main body design and control system of precision WEDM machine tool. The following research is from the articles that relate to my topic that I found when I doing my research. The content of the articles is as follows:In the process of WEDM processing, when the servo feed rate does not match the achievable material removal rate, the wire electrode retraction and lag phenomenon will occur, which is not conducive to the processing efficiency and accuracy in the actual processing process. In this article, Zhi Chena, Guojun Zhang, Fenglin Hana, Yanming Zhang, and Youmin Rong proposed a thermal model to predict the optimal servo feed rate during multi-pulse discharge. At the First, they analyzed the effect of servo feed speed on actual cutting speed and discharge state and determined the optimal servo feed speed. Furthermore, based on the previous thermal model and taking into account the latent heat of evaporation, a modified thermal model is established to obtain discharge crater size in a single pulse discharge process, and this modified model is shown to be more precise than previous thermal models. Following that, a thermal model was established using the single-pulse discharge thermal model to obtain the achievable material removal rate during the multi-pulse discharge process, and experimental data confirmed that the predicted achievable material removal rate was in good agreement with the optimal servo feed rate. Finally, based on the cutting experiment results at various servo feed speeds, it can be determined that the optimal servo feed speed can achieve both a faster actual cutting speed and a narrower kerf width than other servo feed speeds [3].Saikat Mandal, Shirshendu Chakraborty, ParthaPratim Dey fabricated ZrB2-B4C composites with four different compositions by spark plasma sintering (SPS) at 2000C. That is 5, 15, 20, 25 Wt. % of B4C. The composites were characterised by the evolution of physical and mechanical properties, as well as X-Ray Diffraction (XRD) analysis for phase analysis. For all composites, the relative density values obtained ranged from 96.14 to 97.78 percent. The addition of B4C to the ZrB2 matrix increased hardness and fracture toughness. The hardness of ZrB2 ranges from 15.38 GPa at 5% B4C to 20.49 GPa at 25% B4C measured at 1.0 kgf load, and the fracture toughness ranges from 2.93 MPa-m0.5 at 5% B4C to 4.13 MPa-m0.5 at 25% B4C measured at 1.0 kgf load. The composite samples were processed using wire electrical discharge machining (WEDM) with three different parameters set to investigate machining speed and surface roughness. The composite containing 25% B4C has the fastest machining speed of 10.56 mm2 /min. WEDM processed composite surfaces have an average surface roughness (Ra) in the range of 1.265.64 μm [4].Because wire electrodes are slender and flexible, wire deflection and vibration are unavoidable in wire electrical discharge machining (WEDM), and these phenomena are closely related to workpiece surface quality and geometric accuracy. Furthermore, the phenomena of wire deflection and vibration are directly related to wire tension. Zhi Chena, Guojun Zhang, and Hongzhi Yan developed a high-precision constant wire tension control system in this article to reduce wire deflection and vibration and thus improve workpiece surface quality and geometric precision. First and foremost, the factors that cause wire tension fluctuation are briefly discussed. Furthermore, the constant wire tension control system is based on structural improvements to the wire winding system and closed-loop control. The high-precision transfer function of this control system is then deduced using the method of system identification, and three intelligent algorithms are used to tune the PID controller's parameters. Following that, the wire tension control experiment and cutting experiment are performed to assess the performance of this control system. Experiment results show that this control system is capable of controlling wire tension without obvious overshoot. Furthermore, this control system has been shown to improve workpiece surface quality and geometric error, such as surface topography, cutting kerf width, corner error, and taper cutting error. This proposed constant wire tension control system is deserving of widespread adoption and application in the field of practical manufacturing [5].The goals of this article are to precisely manufacture the turbine wheel slot using a novel trim-offset WEDM approach to overcome the challenges of a traditional broaching process. Priyaranjan Sharma, D. Chakradhar, and S. Narendranath are among those who have contributed to this research. In "ELCAM" software, create a 2D model of a turbine wheel groove to generate computer numerical control (CNC) code for fir tree profile geometry. The experimental plan, which is based on a trim-offset approach, is carried out in order to minimize thermal damage and improve surface fatigue strength, both of which are desirable for extending jet engine life. The rough-cut operation has an average cutting speed of 1.5 mm/min and the trim-cut operation has a cutting speed of 5 mm/min. There have six wire types are used to fabricate the turbine wheel slots without wire breakage or gap-short issues. Using B-150 wire, the fabricated profile slots demonstrated an average roughness (Ra) of 0.65 m, profile accuracy within 5 μm, minimum hardness alteration of 34.87 Hv, and negligible recast layer less than 5 μm, and met the essential requirements of the gas turbine industries. When compared to wire-electrochemical-machining (WECM), the trim-offset approach of WEDM is quite advantageous and should be useful for researchers working on "Precision machining of aerospace materials." [6]Cutting stress notches is a critical process in the fracture splitting of connecting rods. This article has proposed a new method of cutting WEDM notches that has the advantages of free threading, low cost, high efficiency, and easy maintenance. Y.J. Zhang, H.P. Luo, G.X. Liu, Z.N. Guo, and Y.J. Tang investigated the machine tool power supply and control system in order to achieve stable cutting quality and higher machining efficiency. A higher-voltage circuit for the pulse power supply is designed in the form of a switching power supply with a dual-controller, which provides the benefits of greater integration, less weight, smaller volume, and lower cost. Furthermore, the output voltage is continuously adjustable and has the function of a voltage regulator, allowing for improved processing quality. The control system is designed to achieve a constant depth of notches while cutting, regardless of the various sizes and tolerances of the inner holes of the connecting rods, thereby eliminating the negative influences on the fracture splitting process caused by stress notches inconsistency. The experimental results show that the presented WEDM power supply and control system can fully meet the requirements of notches cutting in connecting rod fracture splitting processing [7].Syed Asghar Husain Rizvi, Ramesh Kumar Verma, Rajeev Kumar Upadhyay, and Ramesh Kumar Verma developed a model to describe the kerf width during WEDM of die steel D3 using galvanized brass wire. The Response Surface Methodology with Central Composite Design was used, and an orthogonal array was created with peak current, pulse on time, and pulse off time as machining parameters. The effect of WEDM parameters on kerf width was investigated. To determine the value of Kerf Width, micrograph images were taken and measurements were taken. It was discovered that all three of the selected electrical parameters have a significant influence on the Kerf Width. Peak current is the most important electrical parameter for Kerf Width. In the work, higher intensity sparks cause a dimensional shift. The Design Expert's point prediction capability was used to validate the model. The residual error for Kerf Width was found to be 1.08 %, indicating that the model is suitable [8].The setup's normal focus has been on the classic one-dimensional Ra commonly specified in mechanical parts. The EDM process uses 2D patterns for wire and 3D patterns for electrodes, and many functional requirements of engineering surfaces are evaluated using functional roughness parameters, which have received little attention in the literature on EDM setup. Roque Calvo and Manuel Daniel present a systematic search study of the influence of WEDM setup parameters on two very different metal alloys, aluminum A6082 and high-speed steel (HSS) AISI M42, in this article. The experimental methodology includes the Taguchi approach to the design of experiments, correlation, analysis of variance (ANOVA), and multivariate regression. The results demonstrate the surface topography's complexity, a partial description based on standardized roughness parameters, and quantification of the EDM main control factor influences [9].Wire electrical discharge machining is a better choice for machining difficult-to-machine hard materials with high accuracy. This work entails optimising WEDM parameters for improved surface finish and diameter accuracy of tungsten carbide material. S. Sudharsan, R. Arul, C. Veera ajay, and S. Veerakumar use grey relational analysis to optimise process parameters in this article. For the finishing process, three WEDM input variables were chosen: current, pulse off time, and voltage. The roughing process parameters were as follows: current is 6 A, voltage is 8 V, pulse off time is 3 μms, and voltage gap is 55 V. The Taguchi method was used to develop the experimental design. The grey relational analysis determined that the best machining parameters were discharged current of 2 A, voltage of 5 V, and pulse off time of 8 μms. Confirmation tests were performed to validate the results [10].
2. 研究的基本内容、问题解决措施及方案
研究或解决的问题：After these days of research, I found out that the WEDM machine tools on the market are very expensive. If you want to use a good machine tool, it can be as high as 100,000 US dollars，419550 Malaysia ringgit, 631699.97 China yuan but cheaper machines perform poorly.拟采用的研究手段: To overcome this problem, I plan to design a WEDM machinethat have the affordable price and guaranteed performance.
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