US 4,376,880 AGranted

Method of and apparatus for detecting gap conditions in EDM process with monitoring pulses

AssigneeInoue-Japax Research Incorporated

InventorKiyoshi Inoue

Life of this patent

Estimating the term…

Loading patent…

Abstract

Method of and apparatus for controlling electric discharge machining processes in which machining pulses are applied across a machining gap with a pulse duration and peak current preselected to attain a predetermined machining consequence or result. At least one monitoring pulse is interposed in the succession of machining pulses and is time-spaced from and totally independent of the machining pulses while being dimensioned to give rise to a current pulse in the machining gap. The current pulse is measured as to at least one characteristic and the gap condition is determined in response to this measurement. sp CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of copending application Ser. No. 860,164 filed Dec. 13, 1977 (U.S. Pat. No. 4,236,057).

Claims15

Dependent claims

A method of detecting gap conditions in an EDM process, which comprises the steps of:

(a) applying across a machining gap a succession of machining voltage pulses resulting in machining current pulses having a pulse duration and peak current preselected to attain a predetermined machining consequence;
(b) interposing into said succession a plurality of monitoring voltage pulses each time-spaced and independent from adjacent said machining voltage pulses, said monitoring voltage pulses being capable of ionizing said gap and thereby effecting in the gap respective monitoring electrical discharges having individually a pulse duration and peak current preselected independently from said machining current pulses;
(c) measuring a characteristic of said monitoring electrical discharge, thereby classifying it into one of at least two categories;
and
(d) ascertaining the gap condition in response to the result of step (c), each of said machining voltage pulses having its leading edge time-spaced from the trailing edge of the monitoring voltage pulse which precedes each said machining voltage pulse, each of said monitoring voltage pulses having its leading edge time-spaced from the trailing edge of the machining voltage pulse which precedes each said machining voltage pulse.

2 more elements

An apparatus for detecting gap conditions in EDM processes, which comprises:

(a) means for applying across a machining gap a succession of machining pulses;
(b) means for presetting a pulse duration and peak current of said machining pulses;
(c) means for interposing at least one monitoring voltage pulse into said succession of machining pulses, with a leading edge of each monitoring voltage pulse time-spaced from the trailing edge of the machining voltage pulse which precedes each said monitoring voltage pulse, said monitoring voltage pulse being capable of ionizing said gap and thereby effecting in the gap a monitoring electrical discharge;
(d) means for presetting a pulse duration and peak current of said monitoring voltage pulse;
(e) means for measuring a characteristic of a gap current pulse resulting from said monitoring voltage pulse to classify it into one of at least two categories;
and
(f) means responsive to the last-mentioned means for indicating the gap condition.

4 more elements

Dependencies are inferred from the claim text.