Cutting area responsive EDM method and apparatus with cyclically interrupted pulse trains
AssigneeInoue-Japax Research Incorporated
InventorKiyoshi Inoue
Life of this patent
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Abstract
EDM method and apparatus in which the electrical-discharge machining pulses are triggered by the application across the machining gap of a succession of pulse trains of discrete pulses whose durations and intervals may be preset for optimum machining conditions (e.g. surface finish). The instantaneous machining area is detected and a time element, such as the duration of each pulse train or the interval between pulse trains or both, is controlled so as to maintain the current density substantially constant in spite of changing machining areas during the machining process.
Claims15
A method of electrical-discharge machining of a workpiece juxtaposed with a tool electrode across a dielectric-filled machining gap with machining surfaces of variable area as the tool electrode is advanced relatively toward the workpiece so as to maintain the gap spacing therebetween substantially constant, the method comprising the steps of:
- applying across said machining gap pulse trains individually consisting of elementary pulses of predetermined on-time .tau.on and off-time .tau.off, the pulse trains having a duration Ton constituting a first time element and the successive trains being separated by a cut-off interval Toff constituting a second time element;
- sensing the instantaneous area of said machining surfaces during application of said pulse trains across said machining gap;
- and
- controlling at least one of said time elements in accordance with said sensed machining area so as to maintain the current density along said machining surfaces substantially constant in spite of change in said machining area during relative advance of said electrode.
An apparatus for electrical-discharge-machining a workpiece electrode with a tool electrode across a dielectric-filled machining gap with machining surfaces of variable area as the tool electrode is advanced relatively toward the workpiece, comprising:
- power supply means for applying across said gap pulse trains individually consisting of elementary pulses of predetermined on-time .tau.on and off-time .tau.off and having a duration Ton with the successive trains being separated by a cut-off time interval Toff;
- means for sensing the instantaneous area of said machining surfaces to produce an output signal during application of said pulse trains across said machining gap;
- and
- means for controlling at least one of said duration Ton and interval Toff in accordance with said output signal so as to maintain the current density along said machining surfaces substantially constant in spite of change in said machining area during relative advance of said electrodes.
Dependencies are inferred from the claim text.