Arc monitor for electrical discharge machining
First Claim
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1. Apparatus for determining the proportion of discharge time in which arcs occur in electrical discharge machining, comprising:
- filter means for receiving signals representative of the voltage across the discharge gap of an electrical discharge machine, and for passing signals in at least a band of frequencies above a cut-off frequency in the range 1 MHz to 4 MHz;
spark-indication means for generating a spark-indicating signal by determining when the output signal of the filter means exceeds a reference level;
discharge-detection means for receiving signals representative of the said voltage across the gap and for generating a discharge-indication signal while a discharge occurs; and
analysis means for deriving from the spark-indication signal and the discharge-indication signal a signal representative of the proportion of discharge time in which arcs occur.
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Abstract
Apparatus for monitoring EDM is described in which the voltage across the gap between an electrode and a workpiece is passed through a filter which selects those frequencies which are present only during sparking across the gap. The voltage across the gap is also applied to a comparator which detects discharge across the gap by determining whether the gap voltage is between two levels. The proportion of discharge time in which arcs occur is derived by a time-divider circuit which receives signals after processing from the filter and the comparator.
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14 Claims
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1. Apparatus for determining the proportion of discharge time in which arcs occur in electrical discharge machining, comprising:
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filter means for receiving signals representative of the voltage across the discharge gap of an electrical discharge machine, and for passing signals in at least a band of frequencies above a cut-off frequency in the range 1 MHz to 4 MHz; spark-indication means for generating a spark-indicating signal by determining when the output signal of the filter means exceeds a reference level; discharge-detection means for receiving signals representative of the said voltage across the gap and for generating a discharge-indication signal while a discharge occurs; and analysis means for deriving from the spark-indication signal and the discharge-indication signal a signal representative of the proportion of discharge time in which arcs occur. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification