Boots – shoes – and leggings
Patent
1988-04-27
1989-09-19
Ruggiero, Joseph
Boots, shoes, and leggings
219 6912, 36447429, G06F 1546, B23P 108
Patent
active
048687600
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for controlling a power source of a wire electric discharge machine, and more particularly, to an electric discharge machining control apparatus capable of effecting straight machining, corner machining, and arcuate machining in a stable manner, with improved accuracy.
Presently, many wire electric discharge machines use water as a machining fluid. In this case, a leakage current is produced between a wire electrode and a workpiece in accordance with a gap resistance therebetween, whereby electrolysis is effected. In rough machining, the leakage current does not raise any special problem because electric discharge energy is great. In finish machining, however, if the electric discharge energy for each cycle is large, the machined surface of the workpiece is too rough. In order to minimize surface roughness, therefore, the electric discharge energy must be reduced. If the electric discharge energy is too small, however, stable electric discharge cannot be maintained due to the aforesaid leakage current.
In corner machining or arcuate machining for concave portions, the gap resistance is lower, and more leakage current flows than in straight machining, resulting in too small electric discharge energy which permits unstable electric discharge. Conventionally, therefore, electrical conditions, such as current, supply voltage, on/off time for capacitor charge and discharge in a capacitor discharge circuit, etc., are adjusted during corner machining such that the gap resistance is low, and the leakage current is substantial.
If straight machining is performed under electrical conditions such that stable electric discharge can be obtained and the roughness of the machined surface is satisfactory in the corner machining process for concave portions, the electric discharge energy increases due to less leakage current than in the corner machining, so that the machined surface roughness worsens.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide an electric discharge machining control apparatus permitting stable electric discharge in both a straight machining process and a corner or arcuate machining process in finish machining, and ensuring a satisfactory, uniform surface roughness.
In order to achieve the above objects, an electric discharge machining control apparatus according to the present invention includes first memory means for storing electrical conditions responsive to a corner angle; second memory means for storing electrical conditions responsive to the radius of a circular arc; corner angle calculating means for calculating the corner angle at the boundary between adjacent blocks of a numerical control (NC) machining program; radius calculating means for calculating the circular arc radius in response to a circular arc command from the NC machining program; corner machining discrimination means for determining whether corner machining is being performed; and control means operable in response to the result of the determination on the corner machining and the circular arc command, the control means being adapted to change electrical conditions for straight machining over to the electrical conditions read out from the first memory means, in accordance with the calculated corner angle, at the time of the corner machining, and to change the electrical conditions for the straight machining over to the electrical conditions read out from the second memory means, in accordance with the calculated circular arc radius, when the circular arc command is delivered.
According to the present invention, as described above, the straight machining can be performed under optimum electrical conditions, and the optimum electrical conditions for the corner machining can be automatically set in accordance with the corner angle. In both the straight machining and the corner machining, therefore, the electric discharge can be stabilized, the roughness of the machined surface can be minimized, and both straight and
REFERENCES:
patent: 4518842 (1985-05-01), Obara
patent: 4523073 (1985-06-01), Gamo et al.
patent: 4644124 (1987-02-01), Hori et al.
patent: 4700314 (1987-10-01), Kinoshita
patent: 4703146 (1987-10-01), Kinoshita
Fanuc Ltd.
Ruggiero Joseph
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