Method of electrical discharge machining control by monitoring gap resistance
First Claim
1. A method of machining one of a pair of spaced electrodes which define a gap, comprising the steps of effecting at least one electrical discharge between said electrodes during each of a plurality of discharge periods which are separated by intervals free of discharges;
- measuring the electrical resistance of said gap during said intervals;
changing at least the lengths of said intervals when said resistance decreases to a predetermined value, and abruptly moving a selected electrode through a distance which is substantially proportional to a ratio of a number of the plurality of said intervals during which the resistance is substantially at said predetermined value to the total number of said intervals.
0 Assignments
0 Petitions
Accused Products
Abstract
A pair of electrodes are spaced from one another so as to define a gap. One of the electrodes constitutes a workpiece to be machined and the other electrode constitutes a machining tool. To machine the workpiece, groups of electrical discharges are generated between the electrodes. The different groups are separated by pauses which are free of discharges, and the electrical resistance of the electrode gap is measured during the pauses. When the resistance decreases to a critical value, the lengths of the pauses and the spacing between the electrodes are increased until the resistance begins to increase from the critical value. Electrical discharge activity is continued during this time. In the event that these measures fail to cause an increase in the resistance so that the critical value is obtained during several pauses, the electrical discharges are stopped and the machining electrode is abruptly shifted away from the workpiece electrode. The distance moved by the machining electrode is proportional to the frequency of repetition of the critical value and to the period of time for which the resistance remains at such value.
9 Citations
20 Claims
-
1. A method of machining one of a pair of spaced electrodes which define a gap, comprising the steps of effecting at least one electrical discharge between said electrodes during each of a plurality of discharge periods which are separated by intervals free of discharges;
- measuring the electrical resistance of said gap during said intervals;
changing at least the lengths of said intervals when said resistance decreases to a predetermined value, and abruptly moving a selected electrode through a distance which is substantially proportional to a ratio of a number of the plurality of said intervals during which the resistance is substantially at said predetermined value to the total number of said intervals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- measuring the electrical resistance of said gap during said intervals;
-
17. A method of machining one of a pair of spaced electrodes which define a gap, comprising the steps of effecting at least one electrical discharge between said electrodes during each of a plurality of discharge periods which are separated by intervals free of discharges:
- measuring the electrical resistance of said gap during said intervals;
changing at least the lengths of said intervals when said resistance decreases to a predetermined value and when said resistance has substantially said predetermined value during a number of said intervals, abruptly moving a selected electrode through a distance which is substantially proportional to said number. - View Dependent Claims (18, 19, 20)
- measuring the electrical resistance of said gap during said intervals;
Specification