Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 25, Issue 49
Displaying 1-5 of 5 articles from this issue
  • [in Japanese], [in Japanese], [in Japanese]
    1991 Volume 25 Issue 49 Pages 1-8
    Published: July 20, 1991
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
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  • Yoshiyuki UNO, Osamu ENDO, Tbshikatsu NAKAJIMA
    1991 Volume 25 Issue 49 Pages 9-22
    Published: July 20, 1991
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    The purpose of this study is to make clear the crater generation mechanism in electrical dischage machining with a single pulse method, investigating the impact force acting on the workpiece, the shape of crater, the discharge current, the surface of crater, the removed chip and so on. Main conclusions obtained are as follows:
    (1) The impact force acting on the workpiece in a single pulse dischage reaches a maximum value after a few micro seconds from the beginning of spark regardless of the discharge duration.
    (2) The melted volume by a single pulse discharge has a close relation to the discharge energy, and the relation in the air is identical with that in the dielectric fluid.
    (3) The metal removal in a single pulse discharge is mainly caused by melting and vaporization of material for the discharge duration over 10 micro seconds, while impact operation plays main role for the discharge duration under 10 micro seconds.
    (4) Spherical chip produced in electrical discharge includes the composition of tool electrode material, while fragmental chip doesn't.
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  • Improvement of machining accuracy of corner parts in rough-cutting
    Takuji MAGARA, Tsuyoshi YATOMI, Hisashi YAMADA, Kazuhiko KOBAYASHI
    1991 Volume 25 Issue 49 Pages 23-32
    Published: July 20, 1991
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper descrives a detaled research investigation on improvement of machining accuracy of corner parts, especially in rough-cutting of Wire-EDM.
    Because of the use of low-rigidity wire electrodes, it is essential to understand the behavior of wire electrodes in machining process for improvement of machining stabillity and machining accuracy at corner parts. From this point of view, some papers proposed methods of correction by changing machining locus in corner part. However, it is difficult to keep high accuracy at vertical middle parts of workpieces, because conventional correction methods allow bends of wire electrodes.
    In this paper, the bend of the wire electrode can be reduced by changing machining condition at coner parts, as a result, machining errors of corner parts in rough-cutting can be reduced to less than 50% of normal machining.
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  • Kiyoto HASHIGUCHI, Hiroyuki SAWA, Syuuji NITTA
    1991 Volume 25 Issue 49 Pages 33-46
    Published: July 20, 1991
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper presents a study of the ignition by the use of the conductive flour composite resin electrode. By using this composite resin as one side of electrode, the dispersion of Multi-Arc Spots can be formed on the face of opposite metal electrode. The experimental results show that the Multi-Arc spots phenomena are took place during the course of applying one short current pulse accross the narrow gap between the separated electrodes in a kerosene. And also, the sufficient condition has been defined in regard to the occurrence of the Multi-Arc Spots phenomena.
    This composite resin are prepared from mixing up carbon-black or copper flour with metacrylic resin or with poly-tetrafluoro ethylene. These have a property of thermoplastic.
    We are trying to carve a seal on the metal. The steel material (Sk-2) can be removed just like the seal which are carved by using a cutter-nife on the surface of this composite resin electrode. Then, it is a weak point that the wear of the composite resin electrode are not so small in comparison with the steel removal. But, EDM by the use of composite resin electrode will be distinguished on the procedure of forming electrode with ease and economically by making use of the thermo-plastic or thermosetting properties of the resin.
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  • Naotake MOHRI, Nagao SAITO, Hisayoshi NARUMIYA, Hidetoshi KAWATSU, Yos ...
    1991 Volume 25 Issue 49 Pages 47-60
    Published: July 20, 1991
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    In this paper, some results on surface machining by EDM are treated in which several kinds of powder are suspended in working fluid.
    The attainment of fine surface on large area with electrically conductive electrode such as copper is difficult because of its gap electrostatic capacity between electrode and work surface. Silicon electrode method was derived to break through these difficulties. But it is difficult to shape the raw material as a complex formed electrode in this silicon electrode method.
    Several kinds of powder including silicon powder were suspended to dielectric fluid for use of work oil. We have got very fine and uniform surface of 1-2μm Rmax on the work of 100cm2 with copper or graphite electrode.
    The dispersion of discharge current was confirmed widely throughout the whole area of electrode owing to powder suspension.
    EDM by conductive electrode with powders in working oil is very practical in industry.
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