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Volume 26 (1992)
- Issue 53 Pages 1-
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Volume 26, Issue 53
Displaying 1-6 of 6 articles from this issue
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Kiyoto HASHIGUCHI, Yukichi KAMIDE1992 Volume 26 Issue 53 Pages 1-12
Published: November 30, 1992
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn EDM (Electro discharge machining), uniform scattering of micro craters by discharge makes it possible to machine the surface of the workpiece uniformly.
We examined the main factor of the separation of craters created by repeated pulse discharge. We dealed with the phenomena of the creation of two craters by successive two discharges under various discharge conditions.
Experimental results show that the distance between craters is influenced by the pulse interval, the discharge energy, and the gap length. And we concluded that the main factor of the separation is the behavior of the bubble created at discharge.View full abstractDownload PDF (2460K) -
Yoshitsugu MUKOYAMA, You Shen YANG1992 Volume 26 Issue 53 Pages 13-24
Published: November 30, 1992
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSA primary factor of processing mechanism about electrical discharge machining is the vaporizing and melting action of material (electrode and workpiece) near a discharging point and the dynamical action necessary for that melted part is scattered and removed on basis of discharging in liquid.
The analysis of thermal action on discharging part was not considered up to now that thermal physical constant of material which is the basis of the analysis changes depending on the temperatur and a part of melted layer remain. The real state of thermal action was not understood clearly by the analysis of two dimensions.
In this report, the dependence of thermal physical constant of material on temperature and residual melted layer are considered, then the analysis of three dimensions is carried out by using finite element method. The temperature distribution relating to generation of thermal stress is analizing together with that the real state of vaporizing and melting in electrical dischage machining part are made clear.View full abstractDownload PDF (943K) -
Application of Gas-Nitriding Process to EDMed SurfaceMasahiko HIHARA, Yoshitsugu MUKOYAMA1992 Volume 26 Issue 53 Pages 25-34
Published: November 30, 1992
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe purpose of this study is to improve an EDMed surface by application of gas-nitriding process. Evaluation of the effect was made by using thermal fatigue apparatus. Cracks prevented from growing by the nitride layer formed by the process. Total cracks seen on the section of the die steel were considerably fewer in number than EDMed one after a thermal fatigue test. It is suggested that the treatment to EDMed surfaces improves the life of die steels. Furthermore, a nitrided layer was decomposed by the thermal fatigue test and turned into a diffusion one that reduce the growth of the cracks.View full abstractDownload PDF (4601K) -
Computer Simulation of Surface HardeningTomoyuki YONEYAMA, Motoaki OSAWA1992 Volume 26 Issue 53 Pages 35-45
Published: November 30, 1992
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSDownload PDF (5044K) -
Yoshiyuki UNO, Toshikatsu NAKAJIMA, Minoru OKADA1992 Volume 26 Issue 53 Pages 46-57
Published: November 30, 1992
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSMachining mechanism of eletrical discharge machining in deionized water with graphite electrode is experimentally analyzed, investigating crater shape by a single discharge, electrode wear, elementary analysis of machined surface and so on. Main conclusions obtained in this study are as follows:
(1) Specific resistance of water for electrical discharge machining in water is required to be more than 106Ω·cm.
(2) Melting volume produced by a normal polarity single discharge is considerably large as compared with that by reverse polarity.
(3) Normal polarity EDM leads to larger machining rate and larger electrode wear under the same machining condition. Electrode wear in reverse EDM is smaller than that in normal polarity EDM under the same machining rate.
(4) The surface of graphite electrode in reverse polarity EDM is covered with melting workpiece material, while there is no phenomenon like this in the case of normal polarity EDM.
(5) Normal polarity EDM is recommended for improvement of surface quality with a specilal electrode or machining fluid.View full abstractDownload PDF (7306K) -
4th report; Detection of Discharging Position on Die Sinking EDMHaruki OBARA, Akihiro TSUGE1992 Volume 26 Issue 53 Pages 58-68
Published: November 30, 1992
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn 2nd report we described that it was possible to detect a discharging position from discharging current waves or time differential current waves on WIRE EDM.
In 3rd report we analyzed detecting characteristics considering a skin effect in electrode and workpiece for Die sinking EDM and WIRE EDM which had two branched discharging circuits.
Analytical results showed that a shape of gap voltage wave, a discharging pulse duration and loop currents which remained after discharging not only in the branched circuit but also in the electrode and the workpiece, caused detecting errors. To avoid these errors we proposed a new detecting method in which the discharging position was detected from a voltage drop between two branched points on workpiece, but was regularized by a voltage drop on a thick and U-type shunt.
In this report, at first we describe some analyticaly obtained results to decrease the effect of the shape of gap voltage wave, the discharging pulse duration and the loop current for the detection of discharging position from the current wave or the time differential current wave.
Next we describe experimental results in which the discharging position is detected from the time differential current wave.
Finally we describe experimental results in which the discharging position is detected from the voltage drop in workpiece regularized by the voltage drop on U-type shunt. Results show that the detecting accuracy of this method is fine.View full abstractDownload PDF (961K)
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