US3860779A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for positioning an electrode-tool relative to a workpiece in electrical discharge machining
Assignee: Ateliers des Charmilles SA
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Filing: 1973-04-13
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Granted: 1975-01-14
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Expires: 1993-04-13
Abstract
Abstract A method and apparatus for maintaining the gap spacing between the electrode-tool and the workpiece, in electrical discharge machining, at an optimum value providing maximum material removal efficiency and minimum electrode-tool wear. The machining gap is automatically and adaptively maintained at its optimum value by comparing two electrical reference magnitudes, one which varies as a function of the average value of the time delays occurring between the moment at which the machining voltage is applied across the gap and the moment at which the electrical discharge takes place, and the other which is proportional to the rate of gap short circuits, and by deriving from such comparison a reference command signal for the servo system effecting the advance of the electrode-tool relative to the workpiece.
Inventors
- 👤 Georges-Andre Marendaz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:28
CPC Classifications
B; B23; B23H; B23H7/00; B23H7/14; B23H7/18
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
169 words
A method for positioning an electrode-tool relatively to a workpiece in an electro-erosion machining apparatus wherein interrupted electrical discharges are caused to occur across a machining gap between said electrode-tool and said workpiece by way of controlled voltage-current pulses and wherein the machining gap spacing between the electrode-tool and the workpiece is controlled by a command signal applied to a servo system, said method comprising obtaining a first electrical reference signal representative of the rate of random time delay intervals between the moment at which a voltage pulse is applied across the gap and the moment at which current begins to flow through the gap, obtaining a feedback electrical signal representative of the gap spacing between said electrode-tool and said workpiece at said machining gap, and subtracting the magnitude of said feedback signal from the magnitude of said reference signal for obtaining said command signal, wherein the machining gap spacing is maintained about an optimum value for which material removal rate is maximum and electrode-tool wear rate is minimum.
Claim 2
Independent Claim
169 words
A method for positioning an electrode-tool relatively to a workpiece in an electro-erosion machining apparatus wherein interrupted electrical discharges are caused to occur across a machining gap between said electrode-tool and said workpiece by way of controlled voltage-current pulses and wherein the machining gap spacing between the electrode-tool and the workpiece is controlled by a command signal applied to a servo system, said method comprising obtaining a first electrical reference signal representative of the rate of random time delay intervals between the moment at which a voltage pulse is applied across the gap and the moment at which current begins to flow through the gap, obtaining a feedback electrical signal representative of the gap spacing between said electrode-tool and said workpiece at said machining gap, and subtracting the magnitude of said feedback signal from the magnitude of said reference signal for obtaining said command signal, wherein the machining gap spacing is maintained about an optimum value for which material removal rate is maximum and electrode-tool wear rate is minimum.
Claim 3
Dependent Claim
48 words
The method of claim 1 wherein said first electrical reference signal is a function of the average duration of random time delay intervals between the moment at which a machining voltage is applied across the gap and the moment at which current begins to flow through the gap.
Claim 4
Dependent Claim
50 words
The method of claim 1 wherein said first electrical reference signal is a function of the average ratio of the duration of random time delay intervals to the duration of the interval of time comprised between the beginning of a voltage pulse and the beginning of the next voltage pulse.
Claim 5
Dependent Claim
36 words
The method of claim 1 wherein said first electrical reference signal is a function of the average ratio of the duration of random time delay intervals to the duration of a voltage pulse across the gap.
Claim 6
Dependent Claim
37 words
The method of claim 1 wherein said first electrical reference signal is a function of the average ratio of the duration of the random time delay intervals to the duration of a current pulse across the gap.
Claim 7
Dependent Claim
46 words
The method of claim 1 wherein said first electrical reference siginal is a function of the ratio of the number of pulses for which the random time delay duration is greater than a predetermined value to a predetermined number of pulses applied across the machining gap.
Claim 8
Dependent Claim
150 words
The method of claim 1 further comprising obtaining a second electrical reference signal of a magnitude which is representative of the rate of gap short circuits and which is obtained in response to the occurrence across the gap of pulses for which one of the voltage and current parameters during an electrical discharge differs from a predetermined level, and comparing said first and said second electrical reference signals such that said command signal is modified to decrease the gap spacing as a function of a charge of said first electrical reference signal corresponding to an increase of the rate of random time delay intervals and of a modification of said second electrical reference signal corresponding to a decrease of the rate of gap short circuits, wherein the machining gap is maintained about an optimum value for which the material removal rate is maximum and the electrode-tool wear rate is minimum.
Claim 9
Dependent Claim
41 words
The method of claim 7 wherein said second electrical reference signal is obtained in response to the presence or absence of pulses for which the voltage between said electrode-tool and said workpiece during an electrical discharge is below a predetermined level.
Claim 10
Dependent Claim
46 words
The method of claim 8 wherein the signal which represents the machining voltage level during passage of current across the gap which is less than a predetermined level is stored during the time interval comprised between two consecutive current pulses for comparing to said predetermined level.
Claim 11
Dependent Claim
22 words
The method of claim 7 further comprising periodically varying said command signal for varying the machining gap spacing about its optimum value.
Claim 12
Dependent Claim
48 words
The method of claim 7 wherein said first electrical reference signal is a function of the average duration of random time delay intervals between the moment at which a machining voltage is applied across the gap and the moment at which current begins to flow through the gap.
Claim 13
Dependent Claim
50 words
The method of claim 7 wherein said first electrical reference signal is a fucntion of the average ratio of the duration of random time delay intervals to the duration of the interval of time comprised between the beginning of a voltage pulse and the beginning of the next voltage pulse.
Claim 14
Dependent Claim
36 words
The method of claim 7 wherein said first electrical reference signal is a function of the average ratio of the duration of random time delay intervals to the duration of a voltage pulse across the gap.
Claim 15
Dependent Claim
36 words
The method of claim 7 wherein said first electrical reference signal is a function of the average ratio of the duration of random time delay intervals to the duration of a current pulse across the gap.
Claim 16
Dependent Claim
46 words
The method of claim 7 wherein said first electrical reference signal is a function of the ratio of the number of pulses for which the random time delay duration is greater than a predetermined value to a predetermined number of pulses applied across the machining gap.
Claim 17
Dependent Claim
45 words
The method of claim 7 wherein said second electrical reference signal is a function of the average ratio of the time during which the machining voltage detected in the course of a current pulse is less than a predetermined level to a predetermined time interval.
Claim 18
Dependent Claim
53 words
The method of claim 7 wherein said second electrical reference signal is a function of the average ratio of the time interval during which the machining voltage detected in the course of a current pulse is less than a predetermined level to the time during which voltage is applied to the machining gap.
Claim 19
Dependent Claim
52 words
The method of claim 7 whErein said second electrical reference signal is a function of the average ratio of the time interval during which the machining voltage detected in the course of a current pulse is less than a predetermined level to the time during which current flows through the machining gap.
Claim 20
Dependent Claim
52 words
The method of claim 7 wherein said second electrical reference signal is a function of the ratio of the number of pulses for which the machining voltage during the passage of current through the gap is less than a predetermined level to a predetermined number of pulses applied across the machining gap.
Claim 21
Independent Claim
170 words
A method for positioning an electrode-tool relatively to a workpiece in an electro-erosion machining apparatus wherein interrupted electrical discharges are caused to occur across a machining gap between said electrode-tool and said workpiece by way of controlled voltage-current pulses and wherein the machining gap spacing between the electrode-tool and the workpiece is controlled by a command signal applied to a servo system, said method comprising obtaining an electrical reference signal representative of the rate of gap short circuits in response to the occurrence across the gap of pulses for which one of the voltage and current parameters during an electrical discahrge differs from a predetermined level, obtaining a feedback electrical signal representative of the gap spacing between said electrode-tool and said workpiece at said machining gap, and subtracting the magnitude of said feedback signal from the magnitude of said reference signal for obtaining said command signal, wherein the machining gap spacing is maintained about an optimum value for which material removal rate is maximum and electrode-tool wear rate is minimum.
Claim 22
Independent Claim
170 words
A method for positioning an electrode-tool relatively to a workpiece in an electro-erosion machining apparatus wherein interrupted electrical discharges are caused to occur across a machining gap between said electrode-tool and said workpiece by way of controlled voltage-current pulses and wherein the machining gap spacing between the electrode-tool and the workpiece is controlled by a command signal applied to a servo system, said method comprising obtaining an electrical reference signal representative of the rate of gap short circuits in response to the occurrence across the gap of pulses for which one of the voltage and current parameters during an electrical discahrge differs from a predetermined level, obtaining a feedback electrical signal representative of the gap spacing between said electrode-tool and said workpiece at said machining gap, and subtracting the magnitude of said feedback signal from the magnitude of said reference signal for obtaining said command signal, wherein the machining gap spacing is maintained about an optimum value for which material removal rate is maximum and electrode-tool wear rate is minimum.
Claim 23
Dependent Claim
40 words
The method of claim 20 wherein said electrical reference signal is obtained in response to the presence or absence of pulses for which the voltage between said electrode-tool and said workpiece during an electrical discharge is below a predetermined level.
Claim 24
Dependent Claim
44 words
The method of claim 21 wherein the signal which represents the machining voltage level during passage of current across the gap being less than a predetermined level is stored during the time interval between two consecutive current pulses for comparing to said predetermined level.
Claim 25
Dependent Claim
53 words
The method of claim 20 wherein said electrical reference signal is a function of the average ratio of the average time interval during which the machining voltage detected in the couse of a current pulse is less than a predetermined level to the time during which voltage is applied to the machining gap.
Claim 26
Dependent Claim
51 words
The method of claim 20 wherein said electrical reference signal is a function of the average ratio of the time interval during which the machining voltage detected in the course of a current pulse is less than a predetermined level to the time during which current flows through the machining gap.
Claim 27
Dependent Claim
51 words
The method of claim 20 wherein said electrical reference signal is a function of the ratio of the number of pulses for which the machining voltage during the passage of current through the gap is less than a predetermined level to a predetermined number of pulses applied across the machining gap.
Claim 28
Independent Claim
236 words
An apparatus for positioning an electrode-tool relative to a workpiece in an electro-erosion machining apparatus wherein interrupted electrical discharges occur across a machining gap between said electrode-tool and said workpiece by way of controlled voltage and current pulses and wherein the machining gap spacing between the electrode-tool and the workpiece is controlled as a function of a command signal of a predetermined magnitude applied to the input of servo system effecting the advance of the electrode-tool relative to the workpiece, said apparatus comprising means for applying electrical discharges across said machining gap, means for obtaining a feedback signal representative of the actual gap spacing, means for providing a first logic signal representative of the presence of random time delay interVals between the moment at which a voltage is applied across said machining gap and the moment at which current passes through said gap, means for providing a second logic signal representative of the presence during passage of current through said gap of a machining voltage which is less than a predetermined level, means for providing a first electrical magnitude representing the average value of said first logic signal, means for providing a second electrical magnitude representing the average value of said second logic signal, and means for obtaining said command signal by combining said first and second electrical magnitudes for obtaining a reference command signal and by combining said reference command signal and said feedback signal.
Claim 29
Independent Claim
236 words
An apparatus for positioning an electrode-tool relative to a workpiece in an electro-erosion machining apparatus wherein interrupted electrical discharges occur across a machining gap between said electrode-tool and said workpiece by way of controlled voltage and current pulses and wherein the machining gap spacing between the electrode-tool and the workpiece is controlled as a function of a command signal of a predetermined magnitude applied to the input of servo system effecting the advance of the electrode-tool relative to the workpiece, said apparatus comprising means for applying electrical discharges across said machining gap, means for obtaining a feedback signal representative of the actual gap spacing, means for providing a first logic signal representative of the presence of random time delay interVals between the moment at which a voltage is applied across said machining gap and the moment at which current passes through said gap, means for providing a second logic signal representative of the presence during passage of current through said gap of a machining voltage which is less than a predetermined level, means for providing a first electrical magnitude representing the average value of said first logic signal, means for providing a second electrical magnitude representing the average value of said second logic signal, and means for obtaining said command signal by combining said first and second electrical magnitudes for obtaining a reference command signal and by combining said reference command signal and said feedback signal.
Claim 30
Dependent Claim
47 words
The apparatus of claim 26 further comprising means for obtaining said first logic signal by comparing the peak value of said machining voltage pulse with a predetermined reference level, said predetermined reference level being higher than the normal machining voltage during passage of current through the gap.
Claim 31
Dependent Claim
40 words
The apparatus of claim 26 further comprising means for storing said second logic signal during the interval of time between the end of a current pulse and the beginning of the next voltage pulse for comparison to said predetermined level.
Claim 32
Dependent Claim
40 words
The apparatus of claim 26 further comprising means for storing said second logic signal during the interval of time between the end of a current pulse and the beginning of the next current pulse for comparison to said predetermined level.
References Cited (Backward Citations)
US3705287A
Cited
US3739136A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |