Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 28, Issue 58
Displaying 1-4 of 4 articles from this issue
  • Koichi KAWATA, Ryuichi TOYODA, Yoshikazu KAWAUCHI
    1994 Volume 28 Issue 58 Pages 2-14
    Published: July 30, 1994
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper concerns a fabrication of the hologram optical element for a carbon dioxide laser which is used on the scanner installed in the vision sensor of a mobile robot operating under harsh conditions.
    Reactive ion etching (RIE) is employed to obtain a deep grating. The inclination angle of the wall of the grating can be adjusted by varying the oxygen gas flow rate, which varies the volume of undercut. The inclination angle is almost constant for the reactive gas flow condition and is not affected by the mask spacing. The calculated desirable profile of grating can be fabricated under suitable process conditions.
    The irregularity of the fabricated grating profile on the hologram surface affects the local diffraction efficiency variation. As to the depth of the grating, the dimensional accuracy is increased by surrounding the material with a circular wall which evenly distributes the gas flow over the surface. However, the undercut or the inclination of the wall also slightly changes according to the location, and additional mechanical movement of the material or precise control of the gas flow is necessary to increase the accuracy.
    The mean value for the diffraction efficiency of the fabricated hologram is 51.7%. An adequate image for recognition is obtained using a two-dimensional scanner with the hologram element and the galvano-mirror and image reproduction with reflected light from the target.
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  • Influence of Pulse Condition on Machining Characteristics
    Masamitsu TSUCHIYA, Hiroshi YANO, Tsutomu KANEKO, Katsuro OKUYAMA, Shi ...
    1994 Volume 28 Issue 58 Pages 15-23
    Published: July 30, 1994
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Superconducting Ba2YCu3O7-δ ceramics were machined by the electric discharge machining (EDM), using a square-wave-pulse discharge circuit. To maintain stable discharge during machining, a small duty factor, less than 2% depending on the pulse width and the peak current value, was required. A typical machining rate was 70μm/min for a machining electrode of 5mm radius, a puls width of 10μs, and a peak current value of 5.2A. A small discharge energy was preferable to make the inner region of the sample free from damages by the heating effect of the electric discharge. The critical temperature of the Ba2YCu3O7-δ ceramics 50μm below the machined surface was almost identical with that of the bulk.
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  • Yoshiyuki UNO, Akira OKADA, Mitsuru ITOH, Tsuyoshi YAMAGUCHI
    1994 Volume 28 Issue 58 Pages 24-37
    Published: July 30, 1994
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Electrical discharge machining of a deep groove is generally difficult by the conventional method, since the removal of debris generated during the machining becomes more difficult with an increase of the groove depth.
    EDM of groove with a rotating disk electrode is proposed in this paper and the performance of this method is experimentally investigated, comparing with that of conventional method. Main conclusions obtained in this study are as follows;
    (1) The bottom profile of groove machined with a rectangular electrode has complex undulation along the groove, since the smooth flow of dielectric fluid is obstructed.
    (2) Stable EDM of groove is attainable with a rotating disk electrode, since the smooth flow of machining fluid leads to effective removal of debri.
    (3) The machining time of EDM with a rotating disk electrode is shorter than that of EDM with a rectangular electrode for larger number of revolution.
    (4) The groove of setting depth can be generated by controlling the depth of cut according to the analysis of electrode wear in EDM with a rotating disk electrode.
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  • Developments of Prototype Machines and Experiments on Working Conditions
    Koichi KAWATA, Takeo SATO, Takeshi MASAKI, Takahisa MASUZAWA
    1994 Volume 28 Issue 58 Pages 38-48
    Published: July 30, 1994
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    A micro-electrodischarge machine with 3-axis numerical control was developed. The measured discharge gap was less than 1μm in the range of low discharge energy. It was clarified that higher rotating speed of the electrode is preferable in machining with respect to machining time and surface finish. The optimum voltage range was 70 to 100V, and it is preferable to choose higher voltage for shorter machining time and lower voltage for better electrode consumption and accuracy. A better surface finish was obtained with smaller condensor capacitance, and the minimum surface roughness was Rmax 0.1μm. The surface finish was not influenced by voltage.
    A shaft-making machine using the principle of wire electrodischarge grinding (WEDG) was also developed. A better surface finish and accuracy was obtained with spark-out, and a shaft with 5μm diameter was successfully machined.
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