Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 32, Issue 71
Displaying 1-4 of 4 articles from this issue
  • Shin-ichiro KUBOTA, Seiichi YOKOMIZO, Yoshiyuki UNO, Shin-ichi MATSUUR ...
    1998 Volume 32 Issue 71 Pages 10-17
    Published: November 30, 1998
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper deals with micro turning of graphite by excimer laser. Excimer laser has the following characteristics. The wave length is less than 400nm in the range of ultraviolet rays, the pulse duration is about 10-20ns and the peak power reaches about several tens of MW, which lead to low heat damage to workpiece compared with that of YAG laser or CO2 laser. Moreover, it is possible to form the various beam shapes by using the metal mask and reduction optical system. From the above mentioned viewpoints, excimer laser is used for fine precision machining for plastic, ceramic and so on. On the other hand, graphite is superior as an electrode material for EDM, and it has widely been used. However, it is difficult to make a fine complicated shape by traditional processing method because of its brittleness, especially in the case of thin plate less than 1mm. In this study, micro turning of graphite is experimentally investigated with KrF excimer laser and a micro lathe. Main conclusions obtained are as follows:
    (1) It is possible to control the removal amount of graphite less than 1μm per pulse with KrF excimer laser.
    (2) Various rotational symmetrical bodies can be formed by micro turning with trimmed excimer laser.
    (3) The removal efficiency is higher when the irradiation direction of excimer laser is reverse against the rotating direction of workpiece, compared with the opposite case.
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  • Effect of Graphite Electrode
    Takayuki TANI, Yasushi FUKUZAWA, Takuya KAWASE, Katsushi FURUTANI, Nao ...
    1998 Volume 32 Issue 71 Pages 18-26
    Published: November 30, 1998
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Before this report we have shown that EDM of insulating ceramics is possible with an assisting electrode method. The process of assisting electrode method is that a carbonization layer is formed on the ceramics surface by cracked carbon from working oil and this layer keeps electrical conductivity on the ceramics surface during the machining. When ZrO2 ceramics was machined with a copper tool electrode, enough carbonization layer was not formed on the machined surface from cracked carbon, and then machined surface was rough. In this paper, graphite is used as a tool electrode to let promote carbonization reaction. As a result, carbonization reaction is promoted and the enough carbonization layer forms on the machined surface. The surface roughness are much improved comparing with the machined surface by use of copper electrode.
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  • Takayuki KAMITANI, Yoji MARUTANI
    1998 Volume 32 Issue 71 Pages 27-36
    Published: November 30, 1998
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    A new method of making 3-D objects by stereolithography is proposed. To reduce the cost and the size of the system, a short arc discharge lamp is used as a light source instead of the UV laser. To make the fabrication time shorter, multiple spots exposure using optical fibers is employed. Interface software between CAD and stereolithography was developed. The software transforms the 3-D figure data made by CAD to the pixel data for multiple spots exposure. The light beams scan over the surface of the resin using a x-y auto stage and are turned on and off based on the pixel data by shutters. As the result of the basic curing test and the fabrication of 3-D models, the practicality of the system was proved.
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  • Hisashi ISHIDA, Masanori KUNIEDA
    1998 Volume 32 Issue 71 Pages 37-46
    Published: November 30, 1998
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper describes the analysis of formation of the debris particle chains in the narrow gap filled with a dielectric liquid in the EDM process. Since the debris particles are electrically conductive, they reciprocate rapidly between the anode and cathode due to electrophoresis. Patterns of the movement of the debris particles were observed, and it was found that some debris particles are linked each other forming chains of particles and the chains are reciprocating between both electrodes. It was also observed that some debris particle chains are stationary bridging between both electrodes. Since these movements of the debris particles influence on the accuracy and stability of the EDM process, the movement of two debris particles between two plane parallel electrodes was analyzed numerically. Assuming a perfectly elastic collision between the two debris particles, the calculated results show the two debris paricles can not move on the same axis perpendicular to the electrode surfaces. On the other hand, assuming that the particles are bonded each other by some reason, the calculated results coincide well with the observed results that two debris particles are attached and move together aligned parallel to the electric field. Consequently, in order that the debris particles are linked to form chains, not only the electrostatic force, but some adhesion mechanisms, such as Van der Waals force or welding, should be accompanied.
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