Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 14, Issue 28
Displaying 1-4 of 4 articles from this issue
  • Takeshi YATOMI, Kazuhiko KOBAYASHI, Yutaka TANAKA, Yoshio OZAKI
    1981 Volume 14 Issue 28 Pages 1-9
    Published: March 31, 1981
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper deals with the fundamental problems and their solutions in the machining with variable thickness in wire cutting EDM.
    So far, in this kind of machining, there have been such problems that the machining feed rate is not only slower, but also the machining accuracy is worse because of the constant electrical conditions of power supply. Then, the optimum control method has been developed to solve the above problems and was introduced by the first report.
    In this paper, the fundamental experiments were done to investigate the influences to the machining characteristics in the case of machining workpiece with variable thickness, and consequently the new optimum control method was developed on the basis of the above investigations, which appeared to be very effective to the improvement of the machining characteristics such as machining feed rate, machining accuracy.
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  • Mikio MOTOKI, Takeo IKAI
    1981 Volume 14 Issue 28 Pages 10-19
    Published: March 31, 1981
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    A specially designed transistorized pulse generator, which produces a superimposed short pulse on a fundamental rectangular pulse, is applied for machining tungsten carbide alloy with a copper tool electrode in a kerosene dielectric. The polarity of the tool electrode is positive.
    The results obtained are as follows.
    (1) In EDM of tungsten carbide alloy, the successive discharge is exceedingly stable and most of the discharges ignite before the gap voltage reaches no load voltage. Subsequently, the average ignition delay time is close to zero.
    During about 10μs at the beginning of each discharge, the transient extraordinary phenomenon with both high voltage and high frequency oscillation is observed on the waveform of gap voltage.
    (2) As the current intensity of discharge reduces, the successive discharge becomes unstable. It is found from this experiment that the high current pulse with short duration, superimposed at the beginning of each discharge, is sufficiently available to stabilize the successive discharge with low current.
    (3) The effect of the superimposed pulse on the electrode erosion remarkably exerts only in the early stage of discharge, and the removal rate of tungsten carbide alloy can be markedly increased by using the superimposed pulse in comparison with ordinary rectangular pulse.
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  • Investigation about Thermal Process towards Electrode
    Yoshitsugu MUKOYAMA, Isao OGATA
    1981 Volume 14 Issue 28 Pages 20-29
    Published: March 31, 1981
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In the electric discharge machining, supplied pulse form of machining energy is important factor for improvement of machining characteristics, exclusion of machining defects, etc. Though a lot of supplied pulse form of machining energy can be assumed, the problem of trouble some or easy to generate and supply practically is important matter. Further, in investigation of thermal process to electrode, it is necessary to consider the effects of remaining heat after over supplied machining energy. Considering these two points, the thermal process (melting form, condition of stress distribution and depth of generated crack) are calculated by means of Monte Carlo method, in the cases of some energy pulse forms which are superimposed triangular pulse form on rectangular pulse form.
    In consequence, many of informations that will be required to machining experiments, were obtained. In general meaning, it became clear the energy supplied pulse form superimposed triangular pulse form, which rising and falling inclinations are equal, is more advantageous in the point of machining characteristics and machining defects.
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  • Wire Vibration and Discharge Phenomena
    Kenichiro HORIO, Natsuo KINOSHITA, Masahiko FUKUI
    1981 Volume 14 Issue 28 Pages 30-41
    Published: March 31, 1981
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    For improving the performance of wire-EDM, the behaviour of wire electrode in working gap have to be investigated. But there have not been any paper dealing with its dynamic behaviour. The existence of electrical or optical noise in working gap have disturbed direct measurement of wire behaviour.
    The authors have successed to measure the wire behaviour directly and taken notice of the relationship between wire vibration and discharge phnomena by spectrum analysis of both wire vibration and smoothed discharge current.
    In conclusion following things are found out. Wire vibration occurs when machining sturts and is not affected by wire feeding and machining water supply. The amplitude of wire vibration along right-angled direction of machining is always bigger than that along machining direction. Wire vibration has inherent component on wire feeding system and uninherent one. The frequency of inherent component is equal to twice of that of vibration of normal mode. Smaller the amplitude becomes, higher the frequency of uninherent component becomes. There is close relationship between the amplitude of wire vibration and the width of machining gap. There is also close relationship between uninherent component of wire vibration along machining direction and periodic discharge concentration.
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