Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 27, Issue 54
Displaying 1-4 of 4 articles from this issue
  • Ken-ichi KOREYEDA
    1993 Volume 27 Issue 54 Pages 1-10
    Published: March 31, 1993
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    This paper describes the behavior of primary and secondary wave in a hydraulic shock force which is generated by an electrical discharge in static water pressure.
    A shock force is measured by a transducer of semiconductor strain gauge applied on cantileverwith discharge current.
    The secondary shock wave is generated after negative pressure which caused by the primary wave of a shock force.
    In relation to the primary and secondary wave when static water pressure increases from 0.1MPa to the extent of 0.8MPa, the time duration is shorten and the peak values of two waves are increased, but according to much more static water pressure than 0.8MPa the peak values of two waves are inversely taken tendency of decrease and the secondary wave is affected more than the primary wave by static water pressure.
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  • Mamoru NAKAMURA, Ichinori SHIGEMATSU, Kouzou KANAYAMA, Yukio HIRAI
    1993 Volume 27 Issue 54 Pages 11-19
    Published: March 31, 1993
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Electro-discharge machining (EDM) of some structural intermetallic compounds was carried out by using a die-sinking type EDM machine. Three kinds of cast aluminides, TiAl, Ni3Al and FeAl, were used as workpieces. Their machining properties such as removal rate, wear ratio of tool electrode and roughness of EDMed surface were evaluated. The EDMed surfaces and surfaces of tool electrodes after EDM were analyzed with X-ray diffraction patterns. The remaining strength of EDMed TiAl test pieces was also evaluated by 4 point bending test.
    On all of the EDMed surfaces, cracks caused by shrinkage of the resolidified layers during cooling after discharges were observed. Using copper tool electrodes, each aluminide could be EDMed with small tool wear ratio. It was difficult to machine TiAl workpieces with large removal rate.
    The degree of strength degradation of TiAl test pieces after EDM, was clearly influenced with the lamellate microstructure of the material and the EDM directions.
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  • Hidekazu GOTO, Hachiro TSUCHIYA, Makoto MIYAZAKI
    1993 Volume 27 Issue 54 Pages 20-31
    Published: March 31, 1993
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    CO2 laser-induced thermo-chemical etching characteristics of ZrO2 and Al2O3 ceramics in halogen-containing gas (CF4, C3F8, CF3CF=CF2, C2H4F2) were investigated experimentally. Effects of laser power, laser irradiation time, etching gas, gas pressure, gas flow rate and laser scan speed on ethed depth, ethed region (etched hole diameter or etched groove width), thermal affected region and etched surface roughness were estimated. Following results were obtained. The etching characteristics are highly influenced by etching gas dissociation energy, gas pressure and laser absorptivity of etching gas. With appropriate etching condition, it is possible to drill, groove, cut and surface finish without forming thermal affected layer. In case of surface finishing, repetitive laser scanning with low power laser and high scan speed have a good effect on etched depth and surface roughness.
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  • Change in Physical Properties of Machined Surface
    Masamitsu TSUCHIYA, Tsutomu KANEKO, Katsuro OKUYAMA, Shigetoshi OHSHIM ...
    1993 Volume 27 Issue 54 Pages 32-42
    Published: March 31, 1993
    Released on J-STAGE: March 12, 2010
    JOURNAL FREE ACCESS
    Oxide-superconductor ceramics can be machined by EDM, since these ceramics have an electrical conductivity at room temperature. However, change in physical properties of the machined surface due to the heating effect of electric dischage is supposed to occur, because oxide-superconductors are known to be unstable at temperatures above 450°C.
    In this study, EDM is performed on Ba2YCu3O7-δ superconductor ceramics using a RC discharge circuit, and some physical properties of machined surfaces and machined chips are investigated by means of SEM, X-ray deffraction and electric conductivity measurement. Results obtained are as folloes: (1) A degenerated layer is formed on the machined surface, probably due to resolidification of the melted surface layer. This layer has a high resistivity compared with that of the bulk material. (2) Machined chips, generated by EDM, have an amorphous structure and extremely high resistivity (-103Ω·cm). (3) with the formation of a degenerated layer on the machined surface, peak value of the discharge current decreases down to 75% of the initial value.
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