US3789182A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for electrical discharge machining employing periodic extended pulse off time
Assignee: Colt Industries Inc
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Filing: 1972-02-23
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Granted: 1974-01-29
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Expires: 1992-02-23
Abstract
Abstract Electrical discharge machining is provided by generating a series of rectangular machining power pulses at a controllable on-off time duration. Provision is made for introducing extended off time duration between groups of pulses to contribute to the improvement of cutting stability. In one alternate embodiment of the invention, a single on time pulse is provided intermediate a pair of spaced pulse groups.
Inventors
- 👤 D Verner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:47
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/022
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
123 words
Apparatus for providing electrical discharge machining of a conductive workpiece by passing machining power pulses across a dielectric coolant filled gap, including: a first pulse generator for providing regularly spaced machining power pulses across the gap; a second pulse generator operably connected to said first pulse generator for periodically extending its off-time intermediate a burst of such pulses, said second pulse generator including a counter means for predetermining the number of pulses in each of said bursts; said counter means further including a monostable stage for providing an added on-time pulse during the period of said extended off-time, the duration of said off-time pulse before and after said added on-time pulse having a magnitude equal to at least twice the normal off-time duration.
Claim 2
Dependent Claim
123 words
Apparatus for providing electrical discharge machining of a conductive workpiece by passing machining power pulses across a dielectric coolant filled gap, including: a first pulse generator for providing regularly spaced machining power pulses across the gap; a second pulse generator operably connected to said first pulse generator for periodically extending its off-time intermediate a burst of such pulses, said second pulse generator including a counter means for predetermining the number of pulses in each of said bursts; said counter means further including a monostable stage for providing an added on-time pulse during the period of said extended off-time, the duration of said off-time pulse before and after said added on-time pulse having a magnitude equal to at least twice the normal off-time duration.
Claim 3
Dependent Claim
65 words
The combination as set forth in claim 1 wherein said first pulse generator comprises a free-running multivibrator including a pair of alternately operated on-off time electronic conrol switches and wherein said second pulse generator comprises a second free-running multivibrator of lower frequency of operation for regularly controlling the conduction of said off-time electronic control switch and thereby extending the off-time between groups of said pulses.
Claim 4
Dependent Claim
38 words
The combination as set forth in claim 1 wherein said second pulse generator counter includes a fliP-flop operably connected to said first generator and a gating means for selectively controlling the number of pulses in said pulse bursts.
Claim 5
Dependent Claim
34 words
The combination as set forth in claim 1 wherein said first pulse generator comprises a pair of electronic switches having their respective principal and control electrodes cross-connected for operation in the astable multivibrator mode.
Claim 6
Dependent Claim
29 words
The combination as set forth in claim 1 wherein said added on-time pulse is of like current magnitude to the machining power pulses provided from said first pulse generator.
Claim 7
Dependent Claim
31 words
The combination as set forth in claim 1 wherein said added on-time pulse is of like amplitude and like time duration to said machining power pulses from said first pulse generator.
Claim 8
Dependent Claim
124 words
Apparatus for providing electrical discharge machining of a conductive workpiece by passing machining power pulses across a dielectric coolant filled gap, including: a first pulse generator for providing regularly spaced machining power pulses across the gap; a second pulse generator operably connected to said first pulse generator for periodically extending its off-time intermediate a burst of such pulses, said second pulse generator including a counter means for predetermining the number of pulses in each of said bursts; and further means associated with said second pulse generator for providing an added on-time pulse during the period of said extended off-time, the duration of said off-time pulse before and after said added on-time pulse having a magnitude equal to at least twice the normal off-time duration.
Claim 9
Dependent Claim
124 words
Apparatus for providing electrical discharge machining of a conductive workpiece by passing machining power pulses across a dielectric coolant filled gap, including: a first pulse generator for providing regularly spaced machining power pulses across the gap; a second pulse generator operably connected to said first pulse generator for periodically extending its off-time intermediate a burst of such pulses, said second pulse generator including a counter means for predetermining the number of pulses in each of said bursts; and further means associated with said second pulse generator for providing an added on-time pulse during the period of said extended off-time, the duration of said off-time pulse before and after said added on-time pulse having a magnitude equal to at least twice the normal off-time duration.
Claim 10
Dependent Claim
32 words
The combination as set forth in claim 7 wherein said added on-time pulse is of like amplitude and like time duration to said machining power pulses furnished from said first pulse generator.
References Cited (Backward Citations)
GB759190A
Cited
US3558842A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |