Electric heating – Metal heating – Cutting or disintegrating
Patent
1991-01-02
1993-02-16
Evans, Geoffrey S.
Electric heating
Metal heating
Cutting or disintegrating
219 6912, B23H 736, B23H 702
Patent
active
051873427
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a wire cut electric discharge machine, and more particularly, to a machining fluid supply apparatus capable of supplying machining fluid in an amount enough to ensure stable wire extension even in a finishing operation.
BACKGROUND ART
Generally, a wire cut electric discharge machine comprises upper and lower nozzles respectively provided at upper and lower wire guides, and machining fluid supply pipe lines connected to these nozzles, and is arranged to inject machining liquid from the upper and lower nozzles toward an electric discharge machining region between a workpiece and a wire electrode, to thereby remove the sludge and heat produced during electric discharge machining. For rough machining, the opening degrees of flow regulating valves respectively provided in the machining fluid supply pipe lines are increased, to thereby supply the machining fluid in an amount large enough to remove the sludge and heat that are produced in large quantities during the rough machining. On the other hand, in a finishing operation including a second cut, the valve openings are decreased, so as to reduce a deviation of the wire electrode due to the injection pressure of the machining fluid, to thereby improve machining accuracy.
In the aforementioned type of electric discharge machine, it is known to carry out automatic wire extension by using the machining fluid. Namely, at the time of wire extension, the machining fluid is jetted toward the workpiece from a jet nozzle mounted to the upper nozzle, while the injection of the machining fluid from the lower nozzle is interrupted. Then, the wire electrode is fed from the upper wire guide, while being restricted by the jet of the machining fluid, so that the wire passes through a machining initial hole formed in the workpiece and the wire passage of the lower wire guide, thereby effecting the wire extension.
During a finishing operation, however, since the openings of the flow regulating valves in the machining fluid supply pipe lines are small, the amount of the machining fluid supplied to the jet nozzle is reduced, and hence the injection pressure of the jet stream of machining fluid is lowered. The thus reduced injection pressure sometimes causes an unsuccessful wire extension performed in the middle of a finishing operation.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a wire cut electric discharge machine equipped with a machining fluid supply apparatus capable of supplying machining fluid in an amount large enough to ensure stable wire extension even in a finishing operation.
To achieve the above-mentioned object, a wire cut electric discharge machine of the present invention comprises a main pipe line connecting a machining fluid supply source to an upper nozzle, a bypass pipe line connecting the machining fluid supply source to the upper nozzle, a flow regulating valve provided in the bypass pipe line, and control means for varying an opening of the flow regulating valve in dependence on whether or not the electric discharge machine is operated in a wire extension mode.
As described above, according to the present invention, the opening of the flow regulating valve disposed in the bypass pipe line, which is provided separately from the main pipe line, is varied in dependence on whether or not the electric discharge machine is operated in the wire extension mode. Accordingly, it is possible to supply an amount of machining fluid large enough to permit stable wire extension even in a finishing operation, whereby the wire extension can be reliably performed.
BRIEF DESCRIPTION OF THE DRAWING
The single FIGURE is a schematic diagram showing a principal part of a wire cut electric discharge machine according to an embodiment of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
Referring to the appended drawing, a wire cut electric discharge machine of an embodiment of the present invention comprises a tank 1 for storing machining fluid, a pump 2 for pressurizing the
REFERENCES:
patent: 4833290 (1989-05-01), Obara
Aso Toshiyuki
Hirai Toshio
Evans Geoffrey S.
Fanuc Ltd
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