Patent US4393292A successfully refreshed from Google Patents.
US4393292A
Expired / Lapsed
US
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Method of and apparatus for electrical discharge machining a small and deep hole into or through a workpiece
Assignee: Sodick Co Ltd
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Filing: 1980-08-29
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Granted: 1983-07-12
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Expires: 2000-08-29
Abstract
Abstract An improved method of and apparatus for the electrical discharge machining of a small and deep hole of a diameter of 1 mm or less and a depth-to-diameter ratio of at least 5 into or through a workpiece wherein a water machining fluid medium is used having a specific resistivity of at least 104 ohm-cm and is pumped through a tubular elongated electrode into the machining gap at a pressure of at least 20 kg/cm2, preferably 40 kg/cm2. An ultrasonic vibration is imparted to the elongated tubular electrode longitudinally thereof or transversely thereto.
Inventors
- 👤 Kiyoshi Inoue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:10
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/08; B23H1/02; B23H1/04; B23H7/00; B23H7/38
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
119 words
A method of electrical discharge machining a small and deep hole having a diameter of 1 mm or less and a depth to diameter ratio of at least 5 into or through a workpiece, the method comprising the steps of: juxtaposing a thin and elongated tubular electrode with the workpiece across a machining gap; supplying a water machining fluid through the tubular electrode into the machining gap at a pressure of at least 20 kg/cm 2 ; applying a series of electrical machining pulses between the tubular electrode and the workpiece to cause time-spaced electrical discharges through the machining gap thereby removing material from the workpiece; and advancing the tubular electrode in its longitudinal direction relatively into the workpiece.
Claim 2
Independent Claim
119 words
A method of electrical discharge machining a small and deep hole having a diameter of 1 mm or less and a depth to diameter ratio of at least 5 into or through a workpiece, the method comprising the steps of: juxtaposing a thin and elongated tubular electrode with the workpiece across a machining gap; supplying a water machining fluid through the tubular electrode into the machining gap at a pressure of at least 20 kg/cm 2 ; applying a series of electrical machining pulses between the tubular electrode and the workpiece to cause time-spaced electrical discharges through the machining gap thereby removing material from the workpiece; and advancing the tubular electrode in its longitudinal direction relatively into the workpiece.
Claim 3
Dependent Claim
16 words
The method defined in claim 1 wherein said pressure is at least 25 kg/cm 2 .
Claim 4
Dependent Claim
16 words
The method defined in claim 2 wherein said pressure is at least 40 kg/cm 3 .
Claim 5
Dependent Claim
22 words
The method defined in claim 1 wherein said water machining fluid is of a specific resistivity of at least 10 4 ohm-cm.
Claim 6
Dependent Claim
23 words
The method defined in claim 1, claim 2, claim 3 or claim 4 wherein said depth to diameter ratio is at least 10.
Claim 7
Dependent Claim
22 words
A method as defined in claim 1, further comprising the step of maintaining the resistivity of said water machining fluid substantially constant.
Claim 8
Dependent Claim
22 words
A method as defined in claim 6, further comprising the step of maintaining the temperature of said water machining fluid substantially constant.
Claim 9
Dependent Claim
34 words
A method as defined in claim 1, further comprising the step of increasing said pressure of the water machining fluid as a function of the depth of the hole being machined in the workpiece.
Claim 10
Dependent Claim
42 words
A method as defined in claim 1, further comprising the step of maintaining the amount of the water machining fluid supplied to the machining gap substantially two or more times by volume of the amount of gases produced in the machining gap.
Claim 11
Dependent Claim
51 words
A method as defined in claim 1 wherein a projection integral with the workpiece is formed in the machined hole, further comprising the step of controlling the ratio l'/l to be not greater than 1/5 where l is the depth of the hole and l' is the height of said projection.
Claim 12
Dependent Claim
20 words
A method as defined in claim 1, further comprising the step of imparting a ultrasonic vibration to said tubular electrode.
Claim 13
Dependent Claim
18 words
The method defined in claim 11 wherein said ultrasonic vibration is of a frequency less than 50 kHz.
Claim 14
Dependent Claim
15 words
The method defined in claim 12 wherein said frequency is not greater than 30 kHz.
Claim 15
Dependent Claim
19 words
The method defined in claim 11 wherein said ultrasonic vibration is of a frequency between 50 to 100 kHz.
Claim 16
Dependent Claim
20 words
The method defined in claim 11 wherein said ultrasonic vibration is of a frequency between 100 kHz and 10 MHz.
Claim 17
Dependent Claim
25 words
A method as defined in claim 11, further comprising the step of superimposing a low-frequency vibration upon said ultrasonic vibration imparted to said tubular electrode.
Claim 18
Dependent Claim
32 words
The method defined in claim 16 wherein said low-frequency vibration is of a frequency between 50 and 500 Hz while said ultrasonic vibration is of a frequency between 1 and 500 kHz.
Claim 19
Dependent Claim
33 words
A method as defined in claim 11 or claim 16, further comprising the step of changing the amplitude of said ultrasonic vibration as a function of the depth of the hole being machined.
Claim 20
Dependent Claim
29 words
A method as defined in claim 11, further comprising the step of changing the amplitude of said ultrasonic vibration in response to a change in a gap electrical variable.
Claim 21
Dependent Claim
22 words
A method as defined in claim 11, further comprising the step of periodically interrupting the ultrasonic vibration imparted to said tool electrode.
Claim 22
Dependent Claim
34 words
The method defined in claim 20 wherein the frequency of interruption of the ultrasonic vibration is in excess of 10 kHz and said ultrasonic vibration is of a frequency in excess of 100 kHz.
Claim 23
Dependent Claim
59 words
The method defined in claim 20 or 21 wherein said machining pulses are a succession of time-spaced or periodically interrupted trains of pulses, said pulses being of a frequency substantially equal to the frequency of said ultrasonic vibration and the frequency of interruption of the machining pulses being substantially equal to the frequency of interruption of said ultrasonic vibration.
Claim 24
Dependent Claim
28 words
The method defined in claim 11 wherein said electrode is urged against said workpiece in light contacting relationship therewith while said ultrasonic vibration is imparted to said electrode.
Claim 25
Dependent Claim
18 words
The method defined in claim 11 wherein said ultrasonic vibration is imparted to said elongated electrode longitudinally thereof.
Claim 26
Dependent Claim
18 words
The method defined in claim 11 wherein said ultrasonic vibration is imparted to said elongated electrode transversely thereto.
Claim 27
Independent Claim
145 words
An apparatus for electrical discharge machining a small and deep hole of a diameter of 1 mm or less and a depth to diameter ratio of at least 5 into or through a workpiece, the apparatus comprising: a thin and elongated tubular electrode of at most a diameter of 0.5 mm juxtaposable with said workpiece to form a machining gap therebetween; fluid supply and pumping means for supplying a water machining fluid through said tubular electrode into said machining gap at a pressure of at least 20 kg/cm 2 ; power supply means for applying a series of electrical machining pulses between said electrode and said workpiece to produce a succession of electrical discharges through said machining gap thereby removing material from said workpiece; and drive means for relatively displacing said tubular electrode and said workpiece to advance said elongated electrode longitudinally into said workpiece.
Claim 28
Independent Claim
145 words
An apparatus for electrical discharge machining a small and deep hole of a diameter of 1 mm or less and a depth to diameter ratio of at least 5 into or through a workpiece, the apparatus comprising: a thin and elongated tubular electrode of at most a diameter of 0.5 mm juxtaposable with said workpiece to form a machining gap therebetween; fluid supply and pumping means for supplying a water machining fluid through said tubular electrode into said machining gap at a pressure of at least 20 kg/cm 2 ; power supply means for applying a series of electrical machining pulses between said electrode and said workpiece to produce a succession of electrical discharges through said machining gap thereby removing material from said workpiece; and drive means for relatively displacing said tubular electrode and said workpiece to advance said elongated electrode longitudinally into said workpiece.
Claim 29
Dependent Claim
32 words
The apparatus defined in claim 26 wherein said fluid supply and pumping means includes an ion-exchange device for maintaining the resistivity of said water machining fluid in excess of 10 4 ohm-cm.
Claim 30
Dependent Claim
29 words
The apparatus defined in claim 27 wherein said fluid supply and pumping means includes means for controlling the temperature of said water machining fluid substantially at a predetermined value.
Claim 31
Dependent Claim
46 words
The apparatus defined in claim 28 wherein said fluid supply and pumping means includes a pump for pumping said water machining fluid into said tubular electrode through fluid conduit means and an accumulator coupled to said fluid conduit means between said pump and said tubular electrode.
Claim 32
Dependent Claim
20 words
An apparatus as defined in claim 26, further comprising vibrator means for imparting an ultrasonic vibration to said tubular electrode.
Claim 33
Dependent Claim
23 words
The apparatus defined in claim 30 wherein said vibrator means is adapted to impart the ultrasonic vibration to the elongated electrode longitudinally thereof.
Claim 34
Dependent Claim
22 words
The apparatus defined in claim 30 wherein said vibrator means is adapted to impart said ultrasonic vibration transversely to said elongated electrode.
Claim 35
Dependent Claim
19 words
An apparatus as defined in claim 30, further comprising means for selectively changing the amplitude of said ultrasonic vibration.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-11 | 1987-01-10 | 1987-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-11 | 1991-01-10 | 1991-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-11 | 1995-01-10 | 1995-07-12 | $7700.00 | Window Closed / Lapsed |