Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 34, Issue 76
Displaying 1-5 of 5 articles from this issue
  • Takeo NAKAGAWA
    2000 Volume 34 Issue 76 Pages 8-17
    Published: July 31, 2000
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Download PDF (14573K)
  • Makoto HIROI, Yoshihito IMAI, Michio NAKANO
    2000 Volume 34 Issue 76 Pages 18-25
    Published: July 31, 2000
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In order to further improve the machining accuracy and machining speed of electrical discharge machining (EDMing), it is necessary to understand the gap condition during the EDMing process. In this paper, a new method of using ultrasonic waves to measure the gap condition is proposed. First, the possibility that the change in the quantity of bubbles existing in the gap between the electrode and the workpiece could be detected as a change in the attenuation factor of ultrasonic waves is confirmed through a fundamental experiment of the proposed detection method. Second, the method is applied to an actual EDMing process with several machining settings. From these experiments, the dissimilarity of the gap conditions under several EDMing processes is clarified and the fact that the gap is filled with bubbles for most of the machining period is confirmed. Third, a comparative experiment is conducted to investigate the influence of the amount of bubbles in the gap on machining efficiency. As a result of the experiment, it is ascertained that machining with a small amount of bubbles has higher efficiency than machining with a large amount of bubbles. These results provide useful information for constructing the most suitable EDMing control system for improving machining performance.
    Download PDF (2535K)
  • Koichi Seimiya, Toshio Fujiwara
    2000 Volume 34 Issue 76 Pages 26-33
    Published: July 31, 2000
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In this paper, the development of a rapid surface finishing method using an ECM process for stainless steel plates of standard size is described. Basic experiments are carried out first with a bar electrode 10mm wide and 3mm thick under a working gap of 0.2mm in order to establish the principle of the finishing process in which a stock removal rate of about 10μm/s is obtained. On the basis of the exprimental results, a trial apparatus which is designed for finishing stainless steel plates of the standard size of up to 5 feet in width is fabricated. It is equipped with a cylindrical electrode of 300mm in diameter to give the maximum peripheral velocity of 10m/s when rotated. Electrolyte is supplied to the working area by not only pumps but also tool rotation. Two masking sheets are extended upstream and downstream, respectively, to restrict the working area to between 8 and 12mm in length. Test runs are carried out to improve the gloss of SUS304 plates 4 feet wide and 8 feet long from the 2B to the BA finish level. The target level of gloss is realized under an electrode gap of 0.6mm with a feed rate of 600mm/min, applied voltage of 35 V and working current of 4000A.
    Download PDF (1072K)
  • Investigation of accretion mechanism
    Hideki TAKEZAWA, Naotake MOHRI, Katsushi FURUTANI
    2000 Volume 34 Issue 76 Pages 34-41
    Published: July 31, 2000
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Accretion machining by electrical discharge machining (EDM) with a high wear rate of green compact or semisintered electrodes has recently been carried out. Also, it has been observed that the wear rate of thin electrodes for various materials is very high with a high discharge current. In this study, a thin tungsten electrode is used for material accretion or surface modification of a small area. For this purpose, continuous discharge and single discharge machining experiments were performed by EDM with a thin electrode. Then the voltage and current waveforms and the cross section of the accreted surface were observed. In accretion machining, these waveforms revealed a continuous short-circuit phenomenon and a wire explosion phenomenon subsequent to the continuous short-circuited state. These observations indicated that the accreted layer was very hard (1000HV) and that the accretion area was very small (150μm in diameter). This clearly indicates that microaccretion machining can be performed using this technique.
    Download PDF (11411K)
  • Kiyonori MASUI, Takumi SONE, Yukihiro SATO, Hisashi MINAMI
    2000 Volume 34 Issue 76 Pages 42-50
    Published: July 31, 2000
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Download PDF (12832K)
feedback
Top