Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 15, Issue 30
Displaying 1-4 of 4 articles from this issue
  • Tsutomu Fujimura, Koji Isuzugawa
    1982 Volume 15 Issue 30 Pages 1-9
    Published: March 31, 1982
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper reports experimental studies on the electric discharge forming.
    Rectangular impulse currents were used to supply energy into the underwater discharging gap. Sheets of metals (Aluminium & Copper) were bulged in free-forming, and the hight of bulge of each sheet was measured.
    The results may be summarized as follows.
    (1) If electric discharges are equal in quantity of electric charge, the bulge in the case of smaller duration of discharge is higher.
    (2) When the durations of discharges are held equal, the squares of bulging hights are related linearly to the amounts of charges.
    (3) The amount of charge has the threshold of bulging.
    (4) The matters described above may be expressed as follows:
    h2=K(QQ)
    where, h: bulging hight,
    K=k1/(k2+T), ΔQQ0+kQT
    Q: amount of discharge,
    T: duration of discharge.
    Effects of the amount of discharge energy on the bulging will be discussed in a later paper.
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  • On the Tensile Strength of Carbon Steel
    Tadao TSUTSUI, Takeo TAMURA
    1982 Volume 15 Issue 30 Pages 10-20
    Published: March 31, 1982
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This present work was carried out in order to investigate the effect of the heat-affected zone by EDM on the mechanical properties for both normalizing and hardened steel. The results are as follows:
    (1) The microhardness of the spark-eroded surface layer is measured for these steels. The surface layer of hardened steel constitutes the tempering layer between the rehardened layer and the parent metal. The heat-affected zone becomes thicker with increasing pulse duration.
    (2) When both material A and B (respectively less 400Hv) are machined by EDM, the tensile strength of these materials is scarcely influenced by the pulse duration.
    (3) When material C (about 600Hv) is machined by EDM, it produces no plastic deformation and represents brittle fracture. The tensile strength of this material is largely reduced with increasing peak current or pulse duration.
    (4) Observation by the scanning electron microscope shows that microcracks in the spark-eroded surface layer reduce the tensile strength and they depend on the pulse duration.
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  • [in Japanese]
    1982 Volume 15 Issue 30 Pages 21-29
    Published: March 31, 1982
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Download PDF (2537K)
  • Mamoru KUBOTA, Yuji TAMURA
    1982 Volume 15 Issue 30 Pages 30-38
    Published: March 31, 1982
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    ECM, EDM, and mechanical grinding are widely used for the machining of hard to cut materials. Duplex combined processes of them, i. e. electrochemical-discharge machining, electrochemical grinding, and electrodischarge grinding compounded with abrasive grains were researched and developed before, but any triplex process has never been reported. This paper describes the character of the triplex combined machining and presents some performances of it using a nickel coated grinding wheel or a graphite pieces ieserted one.
    Experiments were carried out by a reconstructed tool grinding machine with a direct current power source. Work materials were mild steel, high carbon tool steel, stainless steel, and high speed steel. Electrolyte used is 20% water solution of sodium nitrate.
    Experimental results obtained are as follows:
    1) Triplex combined process brings about negative effects if its characteristics are not investigated enough previously.
    2) With a nickel coated wheel triplex process can be performed in a condition of slight sparking and main electrochemical grinding.
    3) Using a graphite pieces inserted wheel triplex process shows good performance with main mechanical removal in heavy discharge and less electrolysis.
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