• 제목/요약/키워드: Electric discharge machine

검색결과 77건 처리시간 0.028초

프리하든 금형강의 정밀 홀 가공에 관한 연구 (A Study on the Precision Hole Machiningof Pre Hardened Mould Steel)

  • 이승철;조규재;박종남
    • 한국기계가공학회지
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    • 제11권2호
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    • pp.98-104
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    • 2012
  • In this paper, precision processing is carried out for the pre hardened steel(HRC 54), which is one of injection mould materials. Processing characteristics are estimated according to the number of tool cutting blade and roundness is observed by the 3-Dimensional measuring machine. The surface roughness affected by the wire electric discharge machining are measured. Cutting component force of STAVOX is the highest in condition of 2F processing because load per a blade of cutting tool is high. Especially, the difference in Fz is over 20N by cutting load. The slower spindle rotation speed and tool feed rate are, the better cutting component force is. The roundness of hole processed in condition of 4F is good because feed rate is able to be fast. When rotation speed is increased, the surface roughness is decreased. The surface roughness acquired in condition of 2F processing is higher about 50% than 4F processing.

정전기 방전 평가를 위한 간이형 도구 개발에 관한 연구 (A Study on the Development of Simulating Tool for Evaluation of Electrostatic Discharge)

  • 최상원
    • 한국안전학회지
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    • 제26권3호
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    • pp.15-22
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    • 2011
  • Explosion and fire cause about 30 reported industrial major accidents a year by ignition source which discharge of electrostatic generated to flammable gas, vapor, dust and mixtures. It brings economically and humanly very large loss that accident was caused by fire and explosion from electrostatic discharge. Thus, it is very important that electrostatic discharge energy is to be control below not to be igniting flammable mixtures. There are two kinds of analysis model for electrostatic discharge, human body model and machine model. Human body model is available the parameter of human's electrical equivalent that capacitance is 100 pF, resistance is $1.5k{\Omega}$. To simulate and visualize the electrostatic discharge from human body need a very expensive and high voltage simulator. In this paper, we measured the value of capacitance and resistance concerned with test materials and sizing of specimen and the value of charged voltage concerned with test specimen and distance to develop an electrostatic charge/discharge simulating tool for teaching with which concerned industrial employee and students. The result of experiments, we conformed that the minimum ignition energy of methane-oxygen mixtures meets well the equation $W=1/2CV^2$, and found out that the insulating material and sizing of equivalent value having human body mode are the poly ethylene of 200 mm and 300 mm of diameter. Developed electrostatic charge/discharge simulating tool has many merits; simple mechanism, low cost, no need of electric power and so on.

고온선박엔진용 MoSi$_2$금속간화합물의 경도와 방전가공특성 (Hardness and EDM Processing of MoSi$_2$Intermetallics for High Temperature Ship Engine)

  • 윤한기;이상필
    • 한국해양공학회지
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    • 제16권6호
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    • pp.60-64
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    • 2002
  • This paper describes the machining characteristics of the MoSi$_2$--based composites through the process of electric discharge drilling with various tubular electrodes. In addition to hardness characteristics, microstructures of Nb/MoSi$_2$laminate composites were evaluated from the variation of fabricating conditions, such as preparation temperature, applied pressure, and pressure holding time. MoSi$_2$-based composites have been developed in new materials for jet engines of supersonic-speed airplanes and gas turbines for high-temperature generators. These high performance engines may require new hard materials with high strength and high temperature-resistance. Also, with the exception of grinding, traditional machining methods are not applicable to these new materials. Electric discharge machining (EDM) is a thermal process that utilizes a spark discharge to melt a conductive material. The tool electrode is almost -unloaded, because there is n direct contact between the tool electrode and the work piece. By combining a non-conducting ceramic with more conducting ceramic, it was possible to raise the electrical conductivity. From experimental results, it was found that the lamination from Nb sheet and MoSi$_2$ powder was an excellent strategy to improve hardness characteristics of monolithic MoSi$_2$. However, interfacial reaction products, like (Nb, Mo)SiO$_2$and Nb$_2$Si$_3$formed at the interface of Nb/MoSi$_2$, and increased with fabricating temperature. MoSi$_2$composites, with which a hole drilling was not possible through the conventional machining process, enhanced the capacity of ED-drilling by adding MbSi$_2$, relative to that of SiC or ZrO$_2$reinforcements.

방전 드릴을 이용한 미세 홀 관통 공정의 전극 소모량 실시간 예측 (Real-Time Prediction of Electrode Wear for the Small Hole Pass-Through by EDM-drill)

  • 최용찬;허은영;김종민;이철수
    • 한국생산제조학회지
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    • 제22권2호
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    • pp.268-274
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    • 2013
  • Electric discharge machining drill (EDM-drill) is an efficient process for the fabrication of micro-diameter deep metal hole. As there is non-physical contact between tool (electrode) and workpiece, EDM-drill is widely used to machine the hard machining materials such as high strength steel, cemented carbide, titanium alloys. The electro-thermal energy forces the electrode to wear out together with the workpiece to be machined. The electrode wear occurs inside of a machining hole. and It causes hard to monitor the machining state, which leads the productivity and the quality to decrease. Thus, this study presents a methodology to estimated the electrode wear amount while two coefficients (scale factor and shape factor) of the logarithmic regression model are evaluated from the experiment result. To increase the accuracy of estimation model, the linear transformation method is adopted using the differences of initial electrode wear differences. The estimation model is verified through experiment. The experimental result shows that within minute error, the estimation model is able to predict accurately.

방전가공시 측면 플러싱 장치를 활용한 가공성 향상 (Improvements of Electro Discharge Machining Process using Side Flushing Devices)

  • 맹희영;박근;신승환
    • 한국공작기계학회논문집
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    • 제15권1호
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    • pp.23-31
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    • 2006
  • The present works concerns a side flushing device for the improvement of the conventional Electric-Discharge Machining(EDM) process. In the EDM process, chips are usually generated as the workpiece is removed, and deposited between the electrode and the workpiece. This sediment degrades the surface finish of the machined product as well as the processing efficiency. In the present study, a flushing device with additional side injection equipments is proposed in order to remove the deposited chips effectively. Through numerical simulations, the validity of the proposed device is verified, and the influence of process parameters is investigated. Experiments have been also carried out in the die sinking EDM process. It was observed that the process efficiency and the surface finish are improved by virtue of the proposed flushing device.

알루미늄합금의 와이어 컷 방전기공 특성에 과한 연구 (A Study of Characteristics of the Wire-cut EDM Process in Aluminum Alloys)

  • 류성기;안순건
    • 한국안전학회지
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    • 제19권2호
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    • pp.21-25
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    • 2004
  • This study deals with the characteristics of wire-cut EDM(Electrical Discharge Machining)process in aluminum alloys. Besides 2 series and 7 series of aluminum alloys for aerospace applications, porous aluminum is tested, which is used for sound absorbing matherial and interior and exterior material of building. Jinyoung JW-30 wire cutting machine was used in this experiment. Tap wate passed a filter and ionization was used as the discharging solution. An immerision method was applied as a cooling method because it separates chips effectively and machinability is good even with low value of electric current. The speed of fabrication was estimated by measuring the travel distance of the work piece and time spent for the movement. As pulse-on-time increased the fabrication speed decreased. On the other hand, as peak voltage of peak current increased the fabrication speed increased. In general 7075 aluminum alloy resulted in higher fabrication speed.

미세 캐비티 방전 가공에서 바닥면 형상 왜곡 (Distortion of the Bottom Surface in Micro Cavity Machining Using MEDM)

  • 임종훈;류시형;제성욱;주종남
    • 한국정밀공학회지
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    • 제20권12호
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    • pp.191-197
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    • 2003
  • As mechanical components are miniaturized, the demand on micro die and mold is increasing. Micro mechanical components usually have high hardness and good conductivity. So micro electrical discharge machining (MEDM) is an effective way to machine those components. In micro cavity fabrication using MEDM, it is observed that the bottom surface of cavity is distorted. Electric charges tend to be concentrated at the sharp edge. At the center of the bottom surface, debris can not be drawn off easily. These two phenomena make the bottom surface of the electrode and workpiece distort. As machining depth increases, the distorted shape of electrode approaches hemisphere. This process is affected by capacitance and the size of electrode. By using a smaller electrode than the desired cavity size and appropriate tool movement, bottom shape distortion can be prevented.

Mechanism and Characteristics of Nano-dispersed Powder by Pulsed Discharge Method

  • Kwon, Young-Soon;Ilyin, Alexander P.
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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    • pp.27-32
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    • 2003
  • The phenomenon of electrical explosion of conductors is considered in the context of the changes in the energy and structural states of the metal at the stages of energy delivery and relaxation of the primary products of EEC. It is shown that these changes are related to the forced interaction of an intense energy flux with matter and to the subsequent spontaneous relaxation processes. The characteristics of nano-sized metal powders are also discussed.

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Distortion of the Bottom Surface in Micro Cavity Machining Using MEDM

  • Lim Jong Hoon;Je Sung Uk;Ryu Shi Hyoung;Chu Chong Nam
    • International Journal of Precision Engineering and Manufacturing
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    • 제6권4호
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    • pp.44-48
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    • 2005
  • As mechanical components are miniaturized, the demands on micro die/mold are increasing. Micro mechanical components usually have high hardness and good conductivity. Micro electrical discharge machining (MEDM) can thus be an effective way to machine those components. In micro cavity fabrication using MEDM, it is observed that the bottom surface of the cavity is distorted. Electric charges tend to be concentrated at the sharp edge, and debris cannot be drawn off easily at the center of the bottom surface. These two phenomena make the bottom surface of electrode and workpiece distort. As machining depth increases, the distorted shape of the electrode approaches hemisphere. This process is affected by both capacitance and the size of electrode. By using a smaller electrode than the desired cavity size and appropriate tool movement, bottom shape distortion can be prevented.

PREDICTION OF RESIDUAL STRESS PROFILE IN SINGLE-SIDED BUTT WELD USING COMPLIANCE METHOD

  • Kim, Yooil;Jeon, Yu-Chul;Kang, Joong-Kyoo;Han, Yong-Sub
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.156-161
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    • 2002
  • It depends on the joint configuration, dimensions and constraints on the joint whether the residual stress at the root of single-sided butt weld is tensile or not. Therefore, recommendation is generally made that high R ratio should be used in the fatigue test of this type of joint in order to prevent excessively long life caused by compressive residual stress. in this research, the residual stress profile in butt weld joint was obtained through compliance method, using successive extension of a slot and measurement of the variation of strain during the slot extension. The residual stress profile was firstly assumed to be the linear summation of Legendre polynomials up to 9th order excluding 0th and 1st order. Strain variation on the surface was measured while the slot was being extended by cutting to find out the 8 unknown coefficients of each polynomial tenn. The cut was made by the electric discharge machine. It was concluded that the residual stress near the surface stayed positive, however, it turned into the negative value as soon as it passed through 2 or 3 mm depth. Several fatigue tests were also carried out under zero stress ratio. Test results showed that fatigue life coincides well with the design cuive of butt joint in British Standards, which supports that it is tensile residual stress that exists near the weld root.

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