Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 30, Issue 63
Displaying 1-3 of 3 articles from this issue
  • Yasuhiro MAKINO, Haruki OBARA, Tsuyoshi OHSUMI, Shinya NIWA
    1996 Volume 30 Issue 63 Pages 1-10
    Published: March 31, 1996
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Cutting previsions of Wire-EDM are spoiled by a wire vibration and a wire deflection during the machining. In some previous reports, wire behaviors were measured and discussed.
    As well known, the wire behavior is affected from a explosive force, a electrostatic force, a electromagnetic force by each discharging and a force caused by flushing of water.
    Especially in these forces, the explosive force by each discharging is the most important and fundamental force. But the strength of the force and the relation between the force and EDM conditions were not cleared in these reports.
    In this report we investigate about forces affecting on the wire behavior during Wire-EDM. These forces are obtained from wire deflections which are detected by a developed optical fiber slit system. The influence of the flushing pressure and the electrostatic force on wire deflections are discussed, and the strength of the explosive force by each discharging and a machined volume of workpiece by each discharging are obtained.
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  • Yoshiyuki UNO, Akira OKADA, Takeshi MORITA, Takashi TAKAGI
    1996 Volume 30 Issue 63 Pages 11-21
    Published: March 31, 1996
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Recently, aluminium alloy has partially been developed as a metal mold for plastic injection molding in place of steel which has conventionally been used. It is expected that the demand of aluminium alloy mold will increase, since lightening of large mold is necessary. However, study on EDM of aluminium alloy has not yet been carried out sufficiently.
    In this study, electrical discharge machining (EDM) performances of aluminium alloy are experimentally investigated. Furthermore, the effects of high speed polarity changing on EDM performance are also discussed. Main conclusions obtained in this study are as follows:
    (1) The removal rate in EDM of aluminium alloy is larger than that of steel because of its low melting point.
    (2) In EDM of aluminium alloy, the removal rate decreases and the appearance of machined surface becomes worse with machining time. These deteriorations can be improved using high speed polarity changing method.
    (3) In the high speed polarity changing EDM of aluminium alloy, the removal rate takes the maximum when the reversed polarity discharge is a little mixed into the normal polarity EDM.
    (4) In the high speed polarity changing EDM of aluminium alloy, the electrode wear takes the minimum when the normal polarity discharge is a little mixed into the reversed polarity EDM.
    (5) The removal rate, the electrode wear and the surface finish in the EDM depend on the ratio of normal polarity discharge to the reversed polarity one regardless of the number of each polarity discharge in a cycle.
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  • Heng XIA, Masanori KUNIEDA, Nobuhiko NISHIWAKI
    1996 Volume 30 Issue 63 Pages 22-28
    Published: March 31, 1996
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In this paper, the temperature time-variation at every point on the electrode surface in the diesinking EDM process is simulated by a finite-difference method, on the basis of experimental results. At first, the energy distributed into a copper electrode is determined by comparing the computed temperatures for given points within the electrode with the measured ones. Then the electrode surface temperature at any time and for any point is simulated with the obtained energy distribution ratio, and the influence of the thermophysical properties of materials on the surface temperature is investigated. It is found that the energy distributed into the copper tool electrode under the used experimental conditions is 34 percent of the total discharge energy. It is also found from computations that the temperature at a discharge point for the material with greater value of thermal dif f usivity such as copper decreases quickly because the speed of energy dif f ussion into the electrode body is quite high.
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