Electric heating – Metal heating – Cutting or disintegrating
Reexamination Certificate
1998-01-30
2001-04-03
Ryan, Patrick (Department: 1725)
Electric heating
Metal heating
Cutting or disintegrating
C219S069140, C219S069120, C219S069170
Reexamination Certificate
active
06211480
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electric discharge machining (EDM) machine for fine holes and an EDM method for fine holes using such machine to process a workpiece by a fine hole machining electrode.
2. Description of the Related Art
In conventional EDM machines for fine holes using a fine solid electrode or tubular electrode, an attempt has been made to decrease deflection of a leading end of the electrode thereby to achieve precise fine hole machining.
A guide for conducting the precise fine hole machining is shown by an intermediate electrode guide mentioned in Japanese Laid Open Patent Publication No. 60-108234, a grease guide mentioned in Japanese Laid Open Patent Publication No. 1-164526, or a bearing guide mentioned in Japanese Laid Open Patent Publication No. 07-285030.
In addition, a method to decrease distortion of the machining electrode by a working fluid is exemplified by a method mentioned in Japanese Laid Open Patent Publication No. 61-76219 in which a thickener is added.
However, in these fine hole EDM machines, the machining electrodes have low rigidity since their diameter &phgr; is not more than 0.3 mm, especially not more than 0.1 mm. Therefore, there are some problems as mentioned below when such solid or hollow electrode is used. That is, even if the intermediate guide mentioned in the publication No. 60-108234 or the like is adopted, it may be difficult to insert the electrode into the fine hole electrode guide. Moreover, it may be difficult to insert the electrode into the intermediate electrode guide or the like for reducing deflection of the electrode tip end.
When the rigidity of the electrode is not sufficient in machining, the electrode is distorted between an electrode holder and the intermediate guide or between the intermediate guide and the electrode guide in feeding the electrode, even if the intermediate guide is provided. In this case, it is hard to feed the electrode as much as required in machining. Consequently, there take place problems that a machining speed becomes slow, that a machining depth limit becomes shallow, and that a machining time increases thereby to deteriorate machining hole accuracy.
In the method of adding the thickener as in the publication No. 61-76219, a machined hole is used as a guide. Thus, it cannot solve the above problems such as the difficulty of inserting electrode into the electrode guide or the intermediate guide.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an EDM machine for fine holes and an EDM method using such machine that can easily insert a fine hole machining electrode with low rigidity into an electrode guide and an intermediate electrode guide and that can improve machining accuracy by feeding the electrode as required in machining while preventing distortion of the electrode, thereby enlarging machining hole depth limit so as to improve machining accuracy of the hole.
According to one aspect of the invention, an EDM machine for a fine hole comprises a machining electrode for machining a fine hole on a workpiece by electric discharge. An electrode holder mounts the machining electrode. An electrode guide guides the machining electrode in approaching a workpiece. An intermediate electrode guide is provided between the electrode holder and the electrode guide. The intermediate electrode holder holds the machining electrode between the electrode holder and the electrode guide when the machining electrode machines the workpiece by electric discharge.
According to another aspect of the invention, an EDM machine for a fine hole comprises a machining electrode for machining a fine hole on a workpiece by electric discharge. An electrode holder mounts the machining electrode. An electrode guide guides the machining electrode in approaching a workpiece. A working fluid supply means supplies a working fluid via a pipe. An axial flow nozzle is supplied with the working fluid from the working fluid supply means via the pipe so as to form an axial flow about an axis of the machining electrode toward the electrode guide.
According to other aspect of the invention, an EDM machine for a fine hole comprises a machining electrode for machining a fine hole on a workpiece by electric discharge. An electrode holder mounts the machining electrode. An electrode guide guides the machining electrode in approaching a workpiece. A coating material coats the machining electrode except a portion thereof mounted to the electrode holder. The coating material is solid at an ordinary temperature. A coated electrode guide is provided on an upper side of the electrode guide so as to guide an end of the machining electrode coated with the coating material to the electrode guide. Heating means is provided on an upper side of the electrode guide. The heating means applies heat of not less than a melting point of the coating material to the coating material covering the machining electrode so as to melt the coating material in the coated electrode guide.
According to still other aspect of the invention, in an EDM method for a fine hole, a fine hole machining electrode is held by an intermediate electrode guide provided between an electrode holder and an electrode guide. An end of the fine hole machining electrode mounted on the electrode holder approaches toward a workpiece via the electrode guide, thereby performing an electric discharge machining. In performing the electric discharge machining, the fine hole machining electrode is held by the intermediate electrode guide so that the electrode holder, the fine hole machining electrode and the intermediate electrode guide are moved as one body.
Further objects and advantages of the invention will be apparent from the following descriptions, reference being had to the accompanying drawings, wherein preferred embodiments of the invention are clearly shown.
REFERENCES:
patent: 4705932 (1987-11-01), Aso et al.
patent: 4707580 (1987-11-01), Aso et al.
patent: 4977303 (1990-12-01), Briffod
patent: 5416289 (1995-05-01), Tanaka
patent: 27 04945 A1 (1977-08-01), None
patent: 31 19660 A1 (1982-12-01), None
patent: 44 33108 A1 (1996-03-01), None
patent: 60-108234 (1985-06-01), None
patent: 1-164526 (1989-06-01), None
patent: 347972 (1991-07-01), None
patent: 07285030 (1995-10-01), None
Elve M. Alexandra
Mitsubishi Denki & Kabushiki Kaisha
Ryan Patrick
Sughrue Mion Zinn Macpeak & Seas, PLLC
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