| 摘要 |
PURPOSE:To rapidly eliminate an unstable state, by a method wherein a circle in a swing shape is divided into the given number of parts, an electrode is moved along a locus in which a part of the divided arc of a circle is partially overlapped with the adjoining arc of a circle, and during electric discharge machining, relative movement between the electrode and a workpiece is made in a manner to return by a specified amount along the locus. CONSTITUTION:Control is effected such that when, during swing movement of an electrode, machining powder stays in a gap between the electrode and a machining hole and an unstable state occurs, the electrode is returned over a locus to a starting point 200 at each circular shape, and thereafter, it is moved upward aside as in a general electric discharge machining device. Control is made such that during regular lifint up, similar motion described above is also performed. Therefore, when an unstable state occurs in the middle of an arc of circle 203 and the unstable state is not eliminated even after the electrode completely returns to a return point 202 along the locus, it is returned toward the starting point 200 along a segment of a line 201. Thus, since both the bottom and the side of a machining hole are increased in a maching gap, discharge of machining powder is improved to rapidly eliminate an unstable state. During regular lifing up, the electrode is returned along the same locus.
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