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Volume 36 (2002)
- Issue 83 Pages 2-
- Issue 82 Pages 5-
- Issue 81 Pages 7-
Volume 36, Issue 81
Displaying 1-6 of 6 articles from this issue
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Application of Automatic Pencil MechanismDong-Yea SHEU, Takahisa MASUZAWA2002 Volume 36 Issue 81 Pages 7-14
Published: March 29, 2002
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSLow cost large-scale production of microholes has become an important technology in various fields for devices such as fuel injection nozzles, inkjet printer heads, fluid sensors and optical fiber connectors. Since the development of WEDG (wire electrode discharge grinding) technology, micro EDM has been an excellent process for machining microholes in metals and alloys. However, it is difficult to achieve mass production of microhole by EDM without supplying electrodes automatically. In this study, a new method of supplying microelectrodes is proposed to achieve large-scale production of microholes. This new prototyping method which combines the twin-WEDG system and the tandem micro-EDM system, is not only for machining microholes continuously but also for supplying microelectrodes automatically at the same time. As a result, large-scale production of microholes is possible using only one setup of the spindle.View full abstractDownload PDF (10218K) -
Study of EDM Conditions and Servo Feed Function of Finish CutHaruki OBARA, Tsuyoshi OHSUMI, Yuya MASAHASHI, Satoshi MIYANISHI, Masa ...2002 Volume 36 Issue 81 Pages 15-23
Published: March 29, 2002
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSUnsuitable EDM conditions for the finish cut on wire EDM result in a concave or a convex wall straightness of the workpiece. It takes a long time to determine the proper EDM conditions for the finish cut because many test cuts of the workpiece are required. In this study, we investigate and discuss the EDM conditions and servo feed functions of the finish cut, by examining relationships between the wire behaviors and the wall straightness of the workpiece. A method of determining EDM conditions for the finish cut is described, based on a balance model of electrostatic force and discharge force acting on the wire. A servo feed function responding to the variation of skimmed depth is investigated. Control methods for responding to the height variation of the workpiece at the finish cut are discussed.View full abstractDownload PDF (2865K) -
Discharge Location and Discharge Voltage in Case of High Current DischargeHaruki OBARA, Masashi YAMADA, Tsuyoshi OHSUMI, Masatoshi HATANO2002 Volume 36 Issue 81 Pages 24-30
Published: March 29, 2002
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSRecently used wire EDM machines generate a triangular high peak discharge current of 500 ampere or more. It is very difficult to detect the true discharge voltage, because the discharge voltage is transformed by the influence of the high discharge current and impedance of the wire. In this study, we investigate the variation of discharge location and the discharge voltage immediately before the wire breakage in the case of high discharge current on wire EDM, in orderto predict the wire breakage. Three methods that compensate the detected discharge voltage are proposed and the investigated results using these methods are described It was found that in the case of low discharge current, phenomena immediately before the wire breakage such as local concentration of discharges and increase of short circuits in the gap, are clearly observed, but it is difficult to observe them in the case of high discharge current.View full abstractDownload PDF (6301K) -
Yoshiyuki UNO, Akira OKADA, Satoshi NAKA, Shoichi YAMAMOTO, Yutaka SAK ...2002 Volume 36 Issue 81 Pages 31-38
Published: March 29, 2002
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSHoning has been widely applied to engine cylinders, hydraulic cylinders, nozzles, valves and so on, since not only surface roughness but also roundness and straightness of a hole can be improved by this process. However, in the case of surface roughness less than 1μm Ry, a burr formed by abrasives significantly influences the surface roughness and makes it difficult to attain a better surface. In addition, the machining efficiency significantly decreases, since loading of the stick occurs frequently and several hones have to be prepared. In this study, in order to achieve high accuracy and efficiency in internal surface finishing with less surface roughness, the fundamental effects of electrochemical finishing after honing on surface integrity in the case of using a honing machine with soluble fluid as an electrolyte, are experimentally discussed.
Experimental analysis clarified that a suitable electrolytic current density condition existed for improving the surface roughness, and also that passive film generation on the machined surface could be prevented by mixing inverse electrolytic current with the normal one. Then, it was pointed out that the surface roughness could be reduced, since only protruding parts were selectively removed under the suitable condition, even when a soluble fluid was used as an electrolyte. Therefore, this method has the possibility of being a highly efficient internal surface finishing process of small holes after honing.View full abstractDownload PDF (11957K) -
Takayuki TANI, Yasushi FUKUZAWA, Kouji NANBU, Naotake MOHRI2002 Volume 36 Issue 81 Pages 39-46
Published: March 29, 2002
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn this paper we describe the machining characteristics of insulating Si3N4 ceramics by using several kinds of powder mixed oil. With powder mixed oil, the removal rate was improved due to discharge dispersion. However, contrary to expectations, the surface roughness was not sufficiently improved by using only the powder mixed oil, since a long pulse discharge that exceeded the settled pulse duration was generated. This phenomenon is often observed in the case of EDM of a high-resistivity material. In order to obtain a smooth surface, the machining was carried out under limited pulse duration with powder mixed oil so that the long pulse could not be generated. Tests revealed that the removal rate in drilling Si3N4 by EDM was almost the same as that by the grinding process and the surface roughness was reduced to 4μmRy.View full abstractDownload PDF (9519K) -
Takashi TAKAGI, Toshiki ITO, Tadashi NORO2002 Volume 36 Issue 81 Pages 47-52
Published: March 29, 2002
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSDownload PDF (8404K)
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