Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 2, Issue 3
Displaying 1-5 of 5 articles from this issue
  • Hisao KURAFUJI, Takahisa MASUZAWA
    1968 Volume 2 Issue 3 Pages 1-16
    Published: September 01, 1968
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper consists of two parts. One contains experimental results about micro-drilling of cemented carbide alloys by EDM, leading to industrial application. The other is theoretical analysis of the wear ratio, characteristic in EDM performed by very low energy pulses (<3μJ/pulse).
    The results are as follows.
    1. Micro-holes with diameters of 6μm and 9μm were drilled to cemented carbide alloy of 50μm thick by EDM.
    Rectangular micro-holes (approximately 40μm×45μm) were machined to the same workpiece by EDM. It takes only 10-15sec. for each of them.
    2. The erosion ratio, (cathode erosion)/(anode erosion), extremely decreases as the energy of each one pulse decreases, independently of materials of electrodes. For example, the ratio is some 10% in most materials when the capacity of condenser is 500pF and the charging voltage is 100V.
    3. The cause of the fact mentioned above has been explained with T-F theory and Mackeown's Formula, as a result lead from the increase of je/j, where je is current density by electrons and j is the total current density.
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  • Ryozo FUJIMOTO, Shigetada TOSHIMA
    1968 Volume 2 Issue 3 Pages 17-31
    Published: September 01, 1968
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Recently, the industrial applications of electron-beam melting, such as welding, evaporation, cutting of thin film resistor and working of semi-conductor, have developed rapidly.
    But electron-beam machines have complex structure, and it is considerably difficult to operate.
    The authors designed the simple electron-beam machine for trial, and worked semi-conductors.
    The experimental results and discussions are as follows;
    1) Cracks of high melting point materials by D. C electron-beam compared with pulsed beams: the former is bigger about twice or three times than the latter, and shows about twice in depth.
    2) By electron-beam bombardment to N-type Ge single crystals are formed miniature recrystallizations.
    And this part of recrystallization converted N-type to P-type.
    The authors studied electrical characteristics of them.
    3) By electron-beam welding alloyed In with N-type Ge, and observed V-I characteristics of P-N junction.
    4) As application of electron-beam spot welding, made InSb alloy on N-type Ge single crystal by way of experiment, and obtained the growth of tiny InSb crystals like small branch.
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  • Machining Mechanism
    Hisao KURAFUJI, Yoshitsugu MUKOYAMA
    1968 Volume 2 Issue 3 Pages 32-47
    Published: September 01, 1968
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    The relation of the discharge energy, discharge duration and electrode material to the melting depth at a discharge point is calculated theoretically from the expression of the thermal conduction, and thus the discharge removal phenomenon is explained from the viewpoints of the melting depth and the suitable discharge duration for melting that can obtain the maximum melting depth.
    Further, the removal quantity and the diameter and depth of the discharge crater are measured in relation to the results of such calculations, and it is confirmed that the results of the calculations agree well with those of experiments.
    Then, the explanation of the discharge removal phenomenon by the thermal conduction theory is supplemented from observations on such phenomena as the creation of metalic oxides on the discharge surface, the creation and accumulation of materials of the carbon group, the transference of material from the electrode on the opposite side.
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  • Effect of Superposed Pulse Current on Electrode Erosion
    Mikio MOTOKI, Chanjung LEE, Masao NAKAJIMA
    1968 Volume 2 Issue 3 Pages 48-56
    Published: September 01, 1968
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    The present paper describes on a research of the electrode erosion phenomena, which were caused by repeating transient arc discharge across a narrow gap between electrodes immersed in a dielectric liquid.
    The arc current wave at the gap is such a compositive waveform as a pulse current superposed on the fundamental current with square wave. The square wave current and the pulse current are obtained by using transistorized circuit and capacitor circuit respectively.
    It became clear that the characteristic of the electrode erosion is remarkably influenced by the phase and shape of waveform of the pulse current which is superposed on the square wave current.
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  • Sukemitsu ITO
    1968 Volume 2 Issue 3 Pages 57-70
    Published: September 01, 1968
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Electrode gap distance is very important in electrochemical machining, because it influences the machining accuracy and the electrode correction is founded on it. In this report equations on the gap distance were mathematically derived.
    (1) The equilibrium gap distance he (cm) is derived as follows he=η·Ex/v·k/ρ where η is current efficiency, E is gap voltage (V), x is specific electrical conductance (Ω-1cm-1), v is feed rate of electrode (cm/s), k is electrochemical equivalent (g/C), ρ is density of work material (g/cm3).
    (2) Considering the concentration of hydrogen gas bubbles and the temperature rise of electrolyte, the equilibrium gap distance is modified as follows he-he(1+0.44EρH/(1-ρH))·2(1-ρH)/(2+ρH) where he is modiffied equilibrium gap distance, ρH is volume concentration of hydrogen gas bubbles.
    (3) From these equations the foundamental contour machined is determined. The optimum stock removal from rough machining to finish is related to the contour accuracy.
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