• Title/Summary/Keyword: Machining

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Determination of Machining Parameters Considering Current Density in Three Dimensional Electrical Discharge Machining (3차원 방전가공에서 전류밀도를 고려한 방전가공조건 결정)

  • 이건범;김정두;최병훈;송희덕
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.3
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    • pp.100-106
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    • 1999
  • Owing to the complexity of electrical discharge machining (EDM) phenomenon, it is very difficult to determine optimal machining parameters fer improving machining performance. This paper proposes a methodology for determining optimal electrical discharge machining parameters, which is maintaining suitable current density for increasing productivity or improving surface roughness. Machining area is closely related on optimal machining parameters in electrical discharge machining process, so calculation of machining area is needed in order to determine optimal machining parameters. In this study machining area, which is corresponding to the machining position, is calculated from intersection curves between the tool surface and a horizontal plane.

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Technical Issues in Pattern Machining (패턴 가공에서의 기술적인 고려사항)

  • 김보현;최병규
    • Korean Journal of Computational Design and Engineering
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    • v.6 no.4
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    • pp.263-270
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    • 2001
  • In stamping-die manufacturing, the first step is to build die patterns for lost wax casting process. A recent industry trend is to manufacture the die pattern using 3-axis NC machining. This study identifies technical considerations of the pattern machining caused by the characteristics of Styrofoam material, and proposes technical methods related to establishing a process plan and generating tool paths for optimizing the pattern machining. In this paper, the process plan includes the fellowing three items: 1) deter-mining a global machining sequence-a sequence of profile, top, bottom machining and two set-ups, 2) extracting machining features from a pattern model and merging them, and 3) determining a machining sequence of machining features. To each machining feature, this study determines the machining start point, generates the approach tool path, and proposes a tool path linking method fur reducing the distance of the cutter rapid motion. Finally, a smooth tool path generation and an automatic feedrate adjustment (AFA) method are introduced far raising the machining efficiency.

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A Study on High Speed Machining Distortion Characteristics of Aluminum Lithium Alloys Wing Rib (Al-Li 합금 윙립의 고속가공 변형특성에 관한 연구)

  • Lee, In-Su;Kim, Hae-Ji
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.6
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    • pp.111-118
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    • 2014
  • Aluminum lithium alloys are new materials developed for lightweight aircraft parts. However, as compared with conventional aluminum alloys in high-speed machining, problems such as tool wear, machining distortion, and cutting ability arise. This study presents the machining distortion characteristics of an Al-Li alloy wing tip in relation to the cutting heat in high-speed machining. A machining experiment was conducted with high-speed machining equipment for an evaluation of the machining distortion characteristics, with each machining stage temperature change of the workpiece machining surface, and the inside and outside temperature changes of the equipment measured. By measuring the amount of distortion of the workpiece before and after machining, the cutting heat was analyzed with regard to its effect on machining distortion in the product.

Development of Ultrasonic Machine with Force Controlled Position Servo System (가공력 제어 위치 서보 시스템을 이용한 초음파 가공기의 개발)

  • 장인배;이승범;전병희
    • Transactions of Materials Processing
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    • v.13 no.3
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    • pp.253-261
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    • 2004
  • The machining technology for the brittle materials such as ceramics are applied to the fields of MEMS(micro electromechanical system) by the progress of new machining technologies such as Etching, Diamond machining, Micro drilling, EDM(Electro discharge machining), ECDM(Electro discharge machining), USM(Ultrasonic machining), LBM(Laser beam machining), EBM(Electron beam machining). Especially, the USM technology can be applied to the dieletric brittle materials such as silicon, borosilicate glass, silicon nitride, quartz and ceramics with high aspect ratio. The micro machining system with machining force controlled position servo is developed in this paper and the optimized ultrasonic machining algorithm is constructed by the force controlled position servo control. The load cell is adapted in the force measuring and the servo control algorithm, suit for the ultrasonic machining characteristics, is estabilished with using the PID auto-tunning functions at the PMAC system which is generally adapted in the field of robot industries. The precision force signal amplifier is constructed with high precision operational amplifier AD524. The vacuum adsorption chuck which is made of titanum and internal flow line is engraved, is used in the workpiece fixing. The mahining results by USM shows that there are some deviation between the force command and the actual machining force that the servo control algorithm should be applied in the machining procedures. Therefore, the constant force controlled position servo system is developed for the micro USM system and by the examination machining process in USM, the stable USM system is realized by tracking the average value of machining force.

A Study about an estimate about machining accuracy of High Speed Machining (고속가공 가공 정밀도 예측에 관한 연구)

  • 이춘만;류승표;정원지;정종윤;고태조
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.04a
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    • pp.460-465
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    • 2003
  • High-speed machining is one of the most effective technology to improve productivity. Because of the high speed and high feed rate, high-speed machining can give great advantages fur the machining of dies and molds. This paper describes on the improvement of machining accuracy in high-speed machining and an estimate about machining accuracy of high-speed machining.

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Effect of Machining Conditions on machining gap in Micro Electrochemical Drilling (미세 전해 구멍 가공에서의 가긍 조건에 따른 가공 간극 변화 특성)

  • Kim, Bo-Hyun;Park, Byung-Jin;Chu, Chong-Nam
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.12 s.177
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    • pp.163-169
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    • 2005
  • Micro hole is ode of basic elements for micro device or micro parts. Micro electrochemical machining (ECM) can be applied to the machining of micro holes less than 50 ${\mu}m$ in diameter, which it is not easy to apply other techniques to. For the machining of passivating metals such as stainless steel, machining conditions should be chosen carefully to prevent a passive layer. The machining conditions also affect the machining resolution, In this paper, machining characteristics of micro ECM were investigated according to machining conditions such as electrolyte concentration and pulse conditions. From the investigation, optimal machining conditions were suggested for micro ECM of stainless steel.

Micro Machining by EDM and ECM (방전 가공과 전해 가공을 이용한 미세 가공)

  • Jeon, Dong-Hun;Kim, Bo-Hyun;Chu, Chong-Nam
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.10
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    • pp.52-59
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    • 2006
  • Micro electrical discharge machining (EDM) and micro electrochemical machining (ECM) were studied for the fabrication of micro structures. Micro EDM has been used to machine micro structures from metals. However, since the tool wear is inevitable during the machining, the tool wear is drawback for the precision machining. Micro ECM is also used for micro machining and produces better surface quality than that of micro EDM. Moreover, since tool electrodes are not worn out, micro ECM is suitable for the precision micro machining. However, the machining rate is lower than that of micro EDM. In this paper, therefore, the hybrid machining process which uses micro EDM as roughing and micro ECM as finishing is introduced. By using this hybrid machining, a hemisphere with $100\;{\mu}m$ radius was fabricated and the efficiency of the process was investigated experimentally.

Optimization of high-speed machining process using constrained R-T characteristic curve (절삭률-공구수명 특성 곡선을 이용한 고속가공 공정의 최적화에 관한 연구)

  • 최용철;김동우;장윤상;조명우;허영무
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.10a
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    • pp.100-105
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    • 2003
  • With the recent development of machining technology, high speed machining process is widely used for-the mold and difficult-to -cut-materials machining since it allows achieving high productivity and surface quality. However, during the high speed machining process, high cutting speed and feed rate can cause abrupt tool life decrease due to rapid rising of the cutting tool temperature. Such situation may cause increase of machining cost. Thus, in this study, developed optimization algorithm is applied to determine optimal machining variables for multiple high speed machining. The R-T characteristic curve for machining economics problems with a linear-lorarithmic tool life model is determined by applying sensitivity analysis. finally, a series of high speed machining experiments are performed to determine the desired optimal machining variables, and the results are analyzed.

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Selection of Machining Condition in High Speed Machining of STD11 (STD11 금형강의 고속가공에서 가공조건 선정)

  • 이춘만;최치혁;고태조;정종윤;정원지
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.8
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    • pp.30-38
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    • 2003
  • High-speed machining is one of the most effective technology to enhance productivity especially for hardened die material. High-speed machining can give great advantages for machining of dies and molds. But selection of machining condition is very difficult because of complicated machining mechanism. This paper presents the selection of machining condition in high-speed machining of STD11. Depth of cut, feed rate and spindle revolution are control factors. The effect of the control factors on surface roughness and machining error in Z-direction is discussed to improve machining accuracy.

Machining Sequence Generation with Machining Times for Composite Features (가공시간에 의한 복합특징형상의 가공순서 생성)

  • 서영훈;최후곤
    • Korean Journal of Computational Design and Engineering
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    • v.6 no.4
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    • pp.244-253
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    • 2001
  • For more complete process planning, machining sequence determination is critical to attain machining economics. Although many studies have been conducted in recent years, most of them suggests the non-unique machining sequences. When the tool approach directions(TAD) are considered fur a feature, both machining time and number of setups can be reduced. Then, the unique machining sequence can be extracted from alternate(non-unique) sequences by minimizing the idle time between operations within a sequence. This study develops an algorithm to generate the best machining sequence for composite prismatic features in a vertical milling operation. The algorithm contains five steps to produce an unique sequence: a precedence relation matrix(PRM) development, tool approach direction determination, machining time calculation, alternate machining sequence generation, and finally, best machining sequence generation with idle times. As a result, the study shows that the algorithm is effective for a given composite feature and can be applicable fur other prismatic parts.

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