Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 11, Issue 22
Displaying 1-8 of 8 articles from this issue
  • [in Japanese], [in Japanese]
    1978 Volume 11 Issue 22 Pages 2-20
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1978 Volume 11 Issue 22 Pages 21-55
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
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  • Behavior of Ferrosoferic Oxide in Reduction or Dissolution in Sodium Chloride Solution
    Nobuo SHIKATA, Sukemitsu ITO
    1978 Volume 11 Issue 22 Pages 56-69
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In order to clarify the removal mechanism of the scale on hot rolled strip steel by electrolytic reaction in sodium chloride solution, the behavior of ferrosoferic oxide, which is a main component of the scale, in reduction or dissolution was investigated.
    Ferrosoferic oxide is not dissoluved by anodic dissolution only. When it is subjected to the treatment of catholic reduction, however, it reduces into the “amorphous substance” which can not be identified with X-ray diffraction, When the “amorphous substance” is subsequently subjected to the treatment of anodic dissolution, it dissoluves in the form of ferrous ions into the electrolyte.
    The reactions is thought to proceed as shown below:
    Anodic reaction: 2H2O→O2+4H++4e-
    Cathodic reactions: Fe3O4+e-→Amorphous substance
    Anodic dissolutions subsequent to catholic reduction:
    Amorphous substance →Fe3++e-
    Amorphous substance →Fe3O4+e-
    2H2O→O2+4H++4e-
    The dissolution rate of the “amorphous substance” increases with the increase of the temperature and the decrease of pH of the electrolyte.
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  • Effect of Thermal Process towards Electrode
    Yoshitsugu MUKOYAMA
    1978 Volume 11 Issue 22 Pages 70-88
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In the electric discharge machining, the phenomena of electrodes (the workpiece and the tool electrode) removal are mainly based on thermal process, and further in these thermal process, it is very important matters to reserch the influences towards electrodes after the energy supplying (electric discharge) for investigating the removal characteristics and the machining defects (residual stresses, inducing of cracks and heat affected zone).
    This report discusses the influences of the thermal process (remaining heat value) after energy supplying (electric discharge) on the removal characteristics, residual stresses and inducing of cracks etc. throught the calculations of heat transmission by means of the Monte Carlo method.
    In the result, it becomes clear that the remaining heat value seriously affects on the melting valume of electrodes, generated size of residual stresses and inducing ratio of cracks.
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  • Wire Electrode Breaking
    Masahiko FUKUI, Natuo KINOSHITA, Gotaro GAMO, Yoshiyuki NOMURA
    1978 Volume 11 Issue 22 Pages 89-99
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper deals with the fundamental problem on the wire electrode breaking in the Wire EDM with RC and transistor switching circuit.
    In the first step, it is examined how to avoid wire electrode breaking phenomena from the electrical condition, the mechanical condition, workpiece condition, wire speed condition, etc..
    In the second step, it is thought that wire breaking is closely connected with the wear of the wire. And so, the tensile strength and the diameter of the wire after working is examined from calculation and experiment. And slso the discharge rate and the wire breaking condition is examined from experiment.
    These results show that the discharge concentration influences the wire electrode breaking.
    These results make it possible to select the experimental condition and method, avoiding the discharge concentration.
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  • Behaviors of Liquid Metal (Mercury) Caused by a Pulse Discharge in Water
    Mikio MOTOKI, Ken YUKIMURA, Hirotaka WADA
    1978 Volume 11 Issue 22 Pages 100-114
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Behaviors of liquid metal (mercury) caused by a transient arc discharge in water (The maximum current is about 125 A of which duration is about 68μs) are studied in relation to the removal mechanism of the electrical discharge machining (EDM). Photographs are taken with an image converter camera or with a single still camera. It is observed that the small luminous particles scatter away from the vicinity of the arc region at the beginning of a bubble expansion. Small particles of the liquid metal, of which the number increases gradually, are also observed to be emitted from the projections created on the mercury electrode and scatter away during the expansion of a gas bubble. In this manner, they are removed from the mercury electrode. These phenomena vanish suddenly when the gas bubble begins to contract. In the case of a solid electrode, many cavities instead of the projections are observed near its surface in a bubble during the time period mentioned above. They also vanish suddenly after the beginning of the contraction of the bubble. It is apparently suggested that the projections observed in the case of the mercury electrode and cavities on the solid electrode are produced by the same reason; that is, these are created at the regions of partially low pressure on the surface of the electrode. Accordingly, these regions seem to be playing an important role in the removal phenomena of the molten metal on the EDM process; that is, it is concluded that the molten metal in the crater might be removed in the form of small particles from the workpiece showing the same removal mechanism as the case of mercury electrode.
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  • Koichi SEIMIYA, Herbert E. FREER
    1978 Volume 11 Issue 22 Pages 115-125
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    The temperature of flowing sodium chloride solution within the ECM gap was measured by means of miniature bead thermistors in order to investigate the temperature distribution across the gap. Eight bead thermistors of 0.5mm∅ and three glass-tubed ones of 1.5mm∅ were inserted into the gap through the perspex wall and plane cathode electrode, respectively, so that their tips were protruded approximately 0.1mm∅ from the surfaces.
    The measurements revealed the existence of a great temperature gradient in the vicinity of the cathode surface. The temperature rise near the cathode could become several times as great as the cross-sectional average value based on Joule's heating theory.
    The significant influence of void fraction of evolved hydrogen gas bubbles was shown by a theoretical work and the experimental result that the higher back pressure yielded the smaller temperature rise.
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  • CIRP Cooperative Research Project
    Kiyonori MASUI, Tsuyoshi TANIMURA
    1978 Volume 11 Issue 22 Pages 126-140
    Published: March 31, 1978
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper deals with the machinability of cemented carbides by EDM carried out as a frame work of the CIRP Cooperative Research Project of the Scientific Technical Committee E (Physical and Chemical Machining). The aim of above is to investigate the correlation between the machining parameters and the surface integrity of the machined pieces.
    The experiments were carried out by well defined test conditions so as to obtain the comparable test results. And also the workpiece material used were delivered by the Technical Secretarat and the University of Aachen as the standard material from one and same production batch.
    In respect to our results following features will be pointed out. Both the minimum depth of micro-cracks and maximum workpiece metal removal rate were obtained at the almost same range of the pulse duration (ti:3-10μs). This similar tendency was observed also among the results of other participants.
    To obtain the sound analysis of the results and to provide the optimum machining conditions further works are still going on with broadened test conditions (different grades or manufacturers of the material, shorter ti, single discharge method, etc.). All these works will be summerized by Heuvelman, Technical Secretary of the Committee, at 28th CIRP of this year.
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