US3562476A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrode depth of travel control for electrical discharge machining apparatus
Assignee: Raycon Corp
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Filing: 1968-03-25
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Granted: 1971-02-09
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Expires: 1988-03-25
Abstract
Abstract An electromechanical control system for controlling the depth of travel of the electrode in the electrical discharge machining of through holes in workpieces. The control system prevents the possibility of shallow holes due to a foreshortened machining pass and also inhibits the unwanted machining of nearby surfaces caused by a machining pass which is too deep, by causing the tapered tip of the electrode to advance just far enough beyond breakthrough point to enable the unworn portion of the electrode to machine the hole to a uniform diameter. The control system responds to changes in the DC level of the filtered gap voltage (the voltage between electrode and workpiece) which occur while the tip of the electrode is breaking through the wall of the workpiece.
Inventors
- 👤 Gary F Rupert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:01
CPC Classifications
B; B23; B23H; B23H7/00; B23H7/14; B23H7/18
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
113 words
In electrical discharge machining apparatus for forming uniform diameter through holes in workpieces wherein said apparatus includes an electrode of substantially uniform diameter having a tip and means for advancing said electrode tip first toward and througH a workpiece, the improvement comprising means operatively associated with said advancing means for sensing the position of said electrode tip relative to said work by detecting a parameter which is a function of impedance across the gap between said electrode and the workpiece, and means responsive to a signal from said sensing means indicating that said tip has traveled substantially completely through a workpiece for actuating said advancing means to terminate advancing movement of said electrode.
Claim 2
Dependent Claim
113 words
In electrical discharge machining apparatus for forming uniform diameter through holes in workpieces wherein said apparatus includes an electrode of substantially uniform diameter having a tip and means for advancing said electrode tip first toward and througH a workpiece, the improvement comprising means operatively associated with said advancing means for sensing the position of said electrode tip relative to said work by detecting a parameter which is a function of impedance across the gap between said electrode and the workpiece, and means responsive to a signal from said sensing means indicating that said tip has traveled substantially completely through a workpiece for actuating said advancing means to terminate advancing movement of said electrode.
Claim 3
Dependent Claim
38 words
Apparatus according to claim 1 wherein said means for sensing the position of said electrode tip comprises means for sensing a signal which is a function of the voltage across the gap between said electrode and the workpiece.
Claim 4
Dependent Claim
48 words
Apparatus according to claim 2 further including voltage filtering means connected to said electrode and operable to filter said gap voltage signal and convert it to a substantially DC voltage, and means connected to said filtering means operable to detect the voltage level of the output thereof. 5.
Claim 5
Dependent Claim
40 words
Apparatus according to claim 3 wherein said last mentioned means is a voltage level detector operable to trigger at a preset voltage level corresponding substantially to the level existing at the time said tip has traveled completely through a workpiece.
Claim 6
Dependent Claim
34 words
Apparatus according to claim 4 further including switch means connected to said voltage level detector and operable on triggering of said voltage level detector to terminate operation of said means for advancing said electrode.
Claim 7
Independent Claim
94 words
The method of forming a through hole of uniform diameter in a metal workpiece by an electrical discharge machining process comprising the steps of: a. providing an; electrode having a tip; b. advancing said electrode tip first through said workpiece; c. sensing the position of said tip relative to said workpiece by detecting a parameter which is a function of impedance across the gap between said electrode and the workpiece; and d. terminating the advance of said electrode responsively to sensed change in said parameter when said tip has traveled completely through the workpiece.
Claim 8
Independent Claim
94 words
The method of forming a through hole of uniform diameter in a metal workpiece by an electrical discharge machining process comprising the steps of: a. providing an; electrode having a tip; b. advancing said electrode tip first through said workpiece; c. sensing the position of said tip relative to said workpiece by detecting a parameter which is a function of impedance across the gap between said electrode and the workpiece; and d. terminating the advance of said electrode responsively to sensed change in said parameter when said tip has traveled completely through the workpiece.
Claim 9
Dependent Claim
31 words
The method according to claim 6 wherein said sensing step includes the step of sensing a signal which is a function of the gap voltage between said electrode and said workpiece.
Claim 10
Dependent Claim
33 words
The method according to claim 7 further including the steps of: a. filtering said gap voltage signal to obtain a substantially DC voltage; and b. sensing the level of the filtered gap voltage.
References Cited (Backward Citations)
US2778925A
Cited
US2980787A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-08 | 1974-08-10 | 1975-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-08 | 1978-08-10 | 1979-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-08 | 1982-08-10 | 1983-02-09 | $7700.00 | Window Closed / Lapsed |