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Volume 27 (1993)
- Issue 56 Pages 1-
- Issue 55 Pages 1-
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Volume 27, Issue 56
Displaying 1-5 of 5 articles from this issue
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Yoshiyuki UNO, Akira OKADA, Toshikatsu NAKAJIMA, Takashi TAKAGI1993 Volume 27 Issue 56 Pages 1-11
Published: November 30, 1993
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe factors which make titanium alloy difficult to EDM are experimentally investigated, analyzing the shape of crater generated by a single discharge, the pile-up time of workpiece, the waveform of successive discharge current, the shape of debris and so on. Then the condition for high efficient electrical discharge machining of titanium alloy is recommended. Main conclusions obtained in this study are as follows:
(1) The pile-up generated by a single discharge in titanium alloy is higher than that in steel, and the pile-up time is also longer.
(2) The removal volume of crater generated by a single discharge in titanium alloy is larger than that in steel, which agrees with the conventional theory that the lower product of melting point and the thermal conductivity of material leads to easier EDMing.
(3) The metal removal rate is lower and the electrode wear is larger for titanium alloy under the conventional EDM condition as compared with those for steel, since the frequent short-circuit results in the unstability of machining.
(4) High efficient and low electrode wear electrical discharge machining of titanium alloy is possible by decreasing the duty factor, since the resting duration is enough for pileup of workpiece and the machining becomes stable.View full abstractDownload PDF (4813K) -
Kiyonori MASUI, Takumi SONE1993 Volume 27 Issue 56 Pages 12-24
Published: November 30, 1993
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThis paper describes the finishing method of the glass beads blasting to the wire-EDMed surface. The EDMed surfaces have been polished and shot-peened within several seconds with the glass beads blasting. The surface roughness is considerably improved without any changing of the dimensional tolerances. The level of the rougness value at the blasted surface is fixed with the grain size of the beads. The higher blasting pressure from nozzle gives the finer roughness to the relatively rough EDMed surface. This method enables the required surface finish without further work. The wear resistance of the blasted specimen is improved than that of the as-EDMed specimen.
The induction of the residual compressive stresses in the blasted surface can be also obtained.View full abstractDownload PDF (10089K) -
Kiyoto HASHIGUCHI, Yukichi KAMIIDE, Hirohumi OKAMOTO, Takeo IKAI, Ichi ...1993 Volume 27 Issue 56 Pages 25-49
Published: November 30, 1993
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSHeat generated by the repeating pulse discharge in EDM affects the surface of workpiece. This heat effect depends on the wave form of the pulse discharge in EDM, for example, peak value of pulse discharge current, pulse duration, duty factor, and so on.
This paper describes the relation between the electrical condition of wave form and the depth of heat effected layer of workpiece. We present fundamental data for determination of the optimum electrical condition in EDM.
We think of the radius of virtual thermal source on producing micro craters by pulse discharge. The radius is derived with due regard to the expansion of arc channel. The depth of transformed layer is calculated from the radius, and is about the same value obtained from the microvickers hardness of workpiece. And we show that the radius can be calculated from the peak value of pulse discharge current and pulse duration, so the depth of heat effected layer can be estimated.View full abstractDownload PDF (9318K) -
The 2nd Report: Observation of the Time Dependence of Electrode WearMasayuki SUZUKI, Naotake MOHRI, Nagao SAITO, Hideki TAKEZAWA1993 Volume 27 Issue 56 Pages 50-57
Published: November 30, 1993
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn order to realize precision machining in EDM, it is needed to avoid the wear of an electrode. In this paper, the wear rate of an electrode, especially the edge portion of the electrode is evaluated by measuring the change of electrode shape in machining. The wear rate of the electrode on the whole is rather small at the beginning of machining. It increases in the progress of time, and reaches to a certain value which depends on the machining condition and the material of the electrode and work piece. At the beginning of machining, the bottom flat portion of the electrode expands owing to carbon layer out of the working fluid and the edge portion of the electrode wears remarkably.View full abstractDownload PDF (3018K) -
Youshen YANG, Yoshitsugu MUKOYAMA1993 Volume 27 Issue 56 Pages 58-73
Published: November 30, 1993
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe quality assurance is a important subject in Electrical Discharge Machining Especially, the stress generated on machined surface is a cause of generating of crack and residual stress, The residual stress causes decrease of fatigue strength, delayed fracture and stress corrosion which affed life and quality of the workpiece and damage reliability of the product.
In this report, according to thermal elastic/plastic theory in which the hysteresis of thermal stresses and strains accompanying distribution of temperature are calculated in order, the analysis on thermal stresses and residual stresses are developed in form of three dimensions of symmetrical axis by means of finite element method, in which the workpiece material's physical properties dependent on temperature are taken into consideration.
The problems about generation of stress in Electrical Discharge Machining are made more clear by this method then the analysis of two dimensions in the past by means of elastic theory in which the plastic strains are not taken into consideration.View full abstractDownload PDF (1215K)
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