Electric heating – Metal heating – Cutting or disintegrating
Patent
1995-02-08
1997-02-25
Evans, Geoffrey S.
Electric heating
Metal heating
Cutting or disintegrating
219 6912, B23H 100, B23H 110
Patent
active
056056389
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This is a National Phase Application of PCT/JP94/00979 filed 16 Jun. 1994 and based, in turn, on Japanese National Application 5-181825 filed 16 Jun. 1993 under the International Convention.
FIELD OF THE INVENTION
The invention relates to an EDM apparatus, i.e. a machine which uses a dielectric fluid containing powder or a dielectric fluid containing no powder as the machining medium.
BACKGROUND OF THE INVENTION
Generally, EDM apparatus can be divided into two types, die-sinking EDM machines and wire-cut EDM machines. A die-sinking EDM machine uses a 3-dimensional tool electrode with a dielectric fluid, such as, for example, an aqueous solution containing kerosene or a high molecular weight compound, in the gap between the electrode and the workpiece, as the machining medium. It machines the workpiece by applying voltage to that gap and generating an electrical discharge across the gap.
On the other hand, a wire-cut EDM machine uses wire made from such material as brass or tungsten of a diameter of 0.02 to 0.03 mm as the tool electrode. It machines the workpiece by running the wire in juxtaposition with the workpiece between a pair of wire guides. It generally uses deionized water or a kerosene based fluid as the dielectric fluid that is present between the wire and the workpiece.
In finish-machining, it is known that using a dielectric fluid with, for example, finely powdered polycrystalline silicon, mixed in it, will provide a good surface roughness on the workpiece and will improve machining stability. British Patent No. 828,336 and U.S. Pat. Nos. 4,392,042 and 4,952,768 disclose the use of this sort of fluid.
If this fluid is used in a wire-cut EDM machine, it could affect the travel of the wire by, for example, powder entering the rotating parts in the work tank, such as the bearings in the rollers provided along the wire conveying route, and, as a result, causing an undesirable effect on the machining. Furthermore, if the powder enters the movable wire guides or into the wire guide assemblies containing the movable electricity feeding elements which supply electricity to the wire, it could hinder the movements of those guides and elements. Also, much labor is required to remove the powder that remains in the wire conveying mechanism and guide assemblies when the machining work is finished.
OBJECTS OF THE INVENTION
one of the objects of the present invention is to provide an EDM apparatus in which powder-containing fluid does not adhere to the necessary parts in the work tank.
Another object of the present invention is to provide an EDM apparatus in which the work of removing the powder-containing fluid adhering to the necessary parts in the work tank is reduced.
SUMMARY OF THE INVENTION
In order to achieve the foregoing objects, the EDM apparatus of the present invention, is an apparatus which uses tool electrodes located in the work tank and machines the workpiece by electrical discharge. It has a housing that accommodates such sliding parts as the electricity feeding element and wire guides for the wire electrode, and has a fluid feeding device that, while supplying powder-containing dielectric fluid to the working gap formed by the wire electrode and the workpiece, introduces powder-free fluid into that housing.
Also, desirably, the EDM apparatus should contain a cover which houses the movable parts located along the wire conveying route, and the fluid feeding device should, during the EDM process using powder-containing fluid, introduce powder-free fluid into that cover.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, advantages and new features of the present invention will become more readily apparent from the following description, references are being made to the accompanying drawing in which:
FIG. 1 is a schematic drawing illustrating an embodiment of the EDM apparatus of the present invention;
FIG. 2 is a sectional view of an embodiment of the upper guide assembly shown in FIG. 1;
FIG. 3 is a sectional view of another em
REFERENCES:
patent: 4392042 (1983-07-01), Inoue
patent: 4857688 (1989-08-01), Aso et al.
patent: 5013432 (1991-05-01), Martinez-Mugica
patent: 5126524 (1992-06-01), Moro et al.
Dubno Herbert
Evans Geoffrey S.
Kateshov Yuri
Sodick Co. Ltd.
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