US2804575A - Arc machining apparatus with periodic power control - Google Patents

Arc machining apparatus with periodic power control Download PDF

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Publication number
US2804575A
US2804575A US459703A US45970354A US2804575A US 2804575 A US2804575 A US 2804575A US 459703 A US459703 A US 459703A US 45970354 A US45970354 A US 45970354A US 2804575 A US2804575 A US 2804575A
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United States
Prior art keywords
gap
tube
circuit
resistor
voltage
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Expired - Lifetime
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US459703A
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English (en)
Inventor
Victor E Matulaitis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Elox Corporation of Michigan
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Elox Corporation of Michigan
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Filing date
Publication date
Priority to NL94837D priority Critical patent/NL94837C/xx
Priority to NL199986D priority patent/NL199986A/xx
Application filed by Elox Corporation of Michigan filed Critical Elox Corporation of Michigan
Priority to US459703A priority patent/US2804575A/en
Priority to CH334396D priority patent/CH334396A/fr
Priority to GB13358/55A priority patent/GB788366A/en
Priority to FR1133899D priority patent/FR1133899A/fr
Priority to DEE10795A priority patent/DE1067546B/de
Application granted granted Critical
Publication of US2804575A publication Critical patent/US2804575A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H1/00—Electrical discharge machining, i.e. removing metal with a series of rapidly recurring electrical discharges between an electrode and a workpiece in the presence of a fluid dielectric
    • B23H1/02—Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges
    • B23H1/022—Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges for shaping the discharge pulse train

Definitions

  • This invention relates to improvements in the art of arc-machining sometimes referred to as spark-machining, electrical-discharge-machining, or metal disintegrating.
  • the arc-machining process employs an electrode, which may be cylindrical, annular, in the form of a screw or of other shape, which electrode is fed toward a conductive workpiece while maintaining a gap therebetween across which an electrical discharge is caused to pass, coolant being maintained in the gap at all times.
  • the electrode may be vibrated in certain instances or it may be fed toward the work in such manner that the gap is maintained constant as the machining operation is carried on.
  • the arc-machining process will remove material at a slower rate than conventional machining, and attempts to increase the rate of material removal by increasing the power of each discharge have been only partially successful because increase in cutting speed has been accompanied by a decrease in accuracy, finish and dimensional control.
  • Another object is to improve the stability of operation of arc-machining apparatus.
  • Another object is to provide an arc-machining circuit wherein a capacitor shunted across the arc gap may be charged through a resistor that, in effect, automatically varies in value from an extremely low value during charging of the capacitor to an extremely high value during discharging thereof.
  • Still another object is to provide in such a circuit automatically operable time control means operable to delay charging of the capacitor for a period after an electrical discharge has occurred across the gap proportionately to the intensity of the discharge, thus providing time for the gap to deionize after arcing, but avoiding unnecessary delay in charging.
  • Fig. 1 is a schematic diagram of a basic arc-machining circuit
  • Fig. 2. is a graphic representation of the operating characteristics of the Fig. l circuit
  • Fig. 3 is a schematic circuit diagram of an improved arc-machining circuit incorporating my invention.
  • Fig. 4 is a schematic circuit diagram of a modified simplified arc-machining circuit embodying the invention.
  • the basic circuit used in a typical arc-machining apparatus comprises a constant potential D. C. source, one side of Patented Aug. 27, 1957 which is connected to a workpiece 10 and the other side to an electrode 12.
  • a resistor 14 is preferably connected in the positive side of the circuit and a condenser 16 is shunted across the gap between the electrode and the work.
  • the electrode 10 may be vibrated axially or it may be fed toward the work without vibration, it being understood that coolant such as water or other solution, preferably a dielectric solution, is on or around the area of the workpiece being eroded.
  • coolant such as water or other solution, preferably a dielectric solution
  • Fig. l circuit Operation of the Fig. l circuit may be understood by reference to Fig. 2. Assuming that when the circuit is established, the electrode 10 is spaced a sufficient" distance from the work 12 to prevent a discharge across the gap, the difference of potential between the electrode and workpiece will increase exponetially with respect to time as indicated by the curve O AB. Sufficient lapse of time will permit the potential difference across the gap to reach a value equal to that of the source. However, in the normal operation of arc-cutting apparatus, the spacing of the electrode and work is such that a discharge will occur across the gap before the potential difference thereacross reaches a value approaching that of the source. This point is designated A on the graph.
  • a discharge across the gap is accompanied by a flow of current derived principally from capacitor 16, which has been previously charged, and as the capacitor discharges, the potential difference across the gap falls rapidly.
  • the capacitor will not completely discharge because at some voltage lower than the discharge voltage, the arc will be interrupted and the capacitor will immediately start to recharge through the resistor 14.
  • Point C on the graph indicates this occurrence.
  • the capacitor 16 again reaches a voltage high enough to cause a discharge across the gap, the phenomenon is repeated and this repetitive action continues as graphically indicated at A, C, D, E, F, G, etc., as long as the electrode and work are maintained in suitable relation.
  • the potential difference at which the material-removing discharge occurs is a function of and is affected by the material ofthe electrode, the material of the workpiece, the surface roughness of the two, the nature of the coolant used in the gap and,.most important of all, the spacing between the electrode and work. It is generally true that as the gap distance is increased, the potential difference across the gap must also increase to maintain the intermittent arcing or sparking necessary for removal of stock.
  • the Fig. 1 circuit will function satisfactorily in an arc-machining apparatus.
  • the circuit will function satisfactorily with almost any value of capacitor between 1 and 30 microfarads, but the rate of stock removalis extremely low.
  • a study of the operating characteristics of the circuit as represented by points A to G in Fig. 2 suggests that disproportionate periods of each individual cycle are spent in charging the condenser; that is to say, the distances CD and EF, as measured on the time scale are very long compared with the distances.
  • a variable resistor the value of which may vary through a wide range-for example, from about two ohms to as much as two or three thousand ohms.
  • means is provided for regulating the etfective value of the resistance automatically in such manner that the instantaneous value shall be high during the periods when current is flowing across the gap and low during periods when no discharge is taking place, at which time the capacitor is charging.
  • my improved circuit incorporates time regulating means operable automatically to delay the start of charging of the gap shunt capacitance until the gap has deionized, or substantially so.
  • the simple resistor of the Fig. 1 circuit has been replaced by a vacuum tube (or bank of tubes) and the inherent ability of the vacuum tube to become alternately conductive and non-conductive, depending upon the amount of grid bias voltage impressed, has been utilized.
  • vacuum tube as used herein to indicate a tube evacuated to as high a degree as possible, in other words, that type of tube known in the art as a hard tube.
  • Such tubes will not pass high currents (as will the so-called sof or gas filled tubes) but have the advantage that they will handle extremely high frequency currents under excellent grid control.
  • a transformer 18 is provided with a primary 20 and a pair of secondaries 22 and 24.
  • the secondaries are respectively connected across a pair of full-wave rectifiers 26 and 28.
  • a pair of similar transformers may be used if desired, it being the object to provide two power sources in series.
  • Leads 30 and 32 extend from the center taps of the respective secondaries to points 58 and 59 of the circuit, a pair of filter condensers 36 and 38 being connected between the secondary leads and the rectifiers as shown.
  • lead 40 connects the anode 42 of a conventional triode vacuum tube 44 with point 46 of the circuit, which point is between the output side of rectifier 28 and condenser 38.
  • the cathode 48 of tube 44 is connected by leads 50 and 51 with workpiece 10, and by lead 52 with one side of capacitor 16.
  • the electrode 12 is connected by leads 53 and 54 with the other side of the capacitor 16 and by lead 55 with point 58 (the latter being connected to condenser 36 by a lead 56 and to the center tap of secondary 22 by lead 30).
  • Grid 69 of tube 44 is connected by lead 61 to a grid leak resistor 62, the other side of which is connected to the cathode 48 of tube 44 by leads 5t) and 51.
  • the grid is also connected to a coupling condenser 64, the other side of which is connected to the anode 66 of a vacuum tube 68.
  • Anode 66 of tube 68 is connected with point 46 of the circuit through a resistor 70, and cathode 72 to the workpiece 10 and thus to the cathode 48 of tube 44.
  • the gap between the electrode 12 and workpiece 10 is shunted by the capacitor 16 and also by a network consisting of a resistor 74 and a condenser 76.
  • the grid 78 of tube 68 is connected to the junction between the resistor 74 and condenser 76 through a source of bias voltage 80.
  • a rectifier 82 is connected between points 84 and 86 of the circuit, the connection being such that current will pass freely at such times that the voltage across capacitor 16 is greater or tends to become greater than the voltage across capacitor 36, and passage of current will be blocked at such times that the voltage across capacitor 16 is less than that across 36.
  • capacitor 76 is also charging, butthe rise in voltage of 76 will lag that of 16 because of the limiting action of resistor 74.
  • the voltage across capacitor 16 will, of course, continue to rise until it reaches the critical value required to break down the gap whereupon a discharge will occur between electrode 12 and workpiece 10. At the instant of initiation of the discharge, the voltage across capacitor 16 is still rising, current is starting to flow across the gap and current is flowing into capacitor 76.
  • the tube 44- in effect, replaces the simple resistor 14 of the Fig. 1 circuit and the shunt capacitance 16 is charged through the'tube. Because the tube will inherently never'become totallynon-conductive, its acts as a variable resistor havingan extremely high value during and just after arc discharge because of the relatively greatnegative bias on grid 60 produced by the action of tube 68 in becoming conductive at the instant of arc discharge.
  • tube 44 rapidly becomes highly conductive, and thus assumes a very low' value of resistance after the arc discharge has taken place and the arc-gap has had time to deionize. This comes about through the action of the network 74, 76, which, because of the delaying action of the resistor 74, permits condenser 76 to. have momentarily a higher voltage than condenser 16. Current flowing from 76 to 16-then, for a short period after discharge, delays buildup of negativevoltage' on grid 7 8 thereby prolonging conduction through tube 68 and giving the gap time to deionize.
  • tube 68 gradually ceases to conduct and positive voltage rises on anode 66, which voltage is almost instantly effective ongrid 60 through condenser 64; Tube 44 thusis triggered and starts to conduct whereupon capacitor 16 is charged.
  • time delay feature is of utmost importance to the highly efiicient operation of the circuit because if the tube 44- is rendered instantaneously conductive after completion of a discharge, ionization of the gap permits discharge at relatively low voltage and instability of operation results.
  • a typical arc-machining apparatus embodying the Fig. 3 circuit has a power supply providing approximately 100 volts between points 46 and 58, and about 40 volts between points 58 and 86.
  • Tube 44 is represented by a bank of fifty-four type 6AS7 or type 6336 triode tubes, and tube 68 may be one type 6AS7 tube.
  • Condenser 16 is usually a variable condenser of five to one hundred microfarads capacity, condenser 76 has about .01 microfarad capacity and resistor 74 a value of one thousand ohms. The other elements have suitable values to suit and are not critical.
  • the tube bank 44 may be increased to as many as a thousand tubes if such power is required, one tube 68 being required for each group of fifty to sixty power tubes.
  • tube 68 is necessary for the purpose of triggering tube 44, the tube 68 acting primarily as an amplifier to provide sufiicient change in voltage across tube 44 to render the latter conductive or non-conductive, as the case may be.
  • a five volt change in voltage across tube 68 causes approximately one hundred volt change across tube 44, which is about that required to reverse the latters function.
  • Fig. 4 shows a simplified circuit wherein the tube 68 has been omitted. I11 the diagram, the same reference characters have been used as in Fig. 3 for the same elements.
  • the grid 60 of tube 44 is connected to one side of the resistor 74 and one side of the workpiece 10, and the condensers 16 and 76 are connected in parallel through the resistor 74.
  • tube 44 Assuming that the tube 44 will reverse function in response to the voltage difierential across the resistor 74 (which is effective on the grid 60), tube 44 remains nonconductive until the voltage across condensers 16 and 76 equalizes sulficiently to change the grid voltage positive-then the tube will conduct.
  • the rectifier 82 serves to limit the voltage which can appear across the gap. to substantiallyv that which can appear between points 53 and 86.
  • This rectifier may be omitted without adversely affecting the operating characteristics of the circuit so far as metal removal is concerned, but its presence is desirable for best overall results as more fully set forth in my co-pending application Serial No. 361,730, filed June 15, 1953.
  • circuit means'for rendering tube 44 instantaneously non-conductive in the event of a short circuit across the gap, but inasmuch as this feature has been fully. described. and claimed in my co-pending application Serial'No. 338,789, filed February 25, 1953, I have omitted, details. herein for the sake of clarity and. simplification.
  • an arc-machining apparatus having an electrode, means for causing intermittent electrical discharge across a gap between said electrode and a workpiece for removing material from the workpiece, a capacitor connected across said gap, means for charging said capacitor from a power source including a charging circuit, a variable resistor in said charging circuit, means for automatically varying said resistor such that the resistance value thereof is at maximum value during discharge across said gap, and means for limiting the instantaneous voltage across the gap to a value substantially lower than that of the power source.
  • an arc-machining apparatus having an electrode adapted to be disposed in spaced proximity to a conductive workpiece, a capacitor connected across the gap between said electrode and the workpiece, a charging circuit for charging said capacitor from a power source such that intermittent electrical discharge will occur across said gap, a variable resistor in said charging circuit, means operable to maintain said resistor at a relatively low value during charging of said capacitor, means operable automatically in response to discharge across said gap for causing said resistor to assume a relatively high value, and means for limiting the instantaneous voltage across the gap to a value substantially lower than that of the power source.
  • an arc-machining apparatus having an electrode adapted to be disposed in spaced relationship with a conducting workpiece, a source of electrical power, a capacitor, a charging circuit for said capacitor, a discharging circuit for said capacitor including the gap between said electrode and the workpiece, a variable resistor in said charging circuit, means operable automatically in response to discharge across said gap for causing said resistor to assume a relatively high value during said discharge and to assume a relatively low value when said discharge ceases, and means for limiting the instantaneous voltage across the gap to a value substantially lower than that of the power source.
  • said last means includes time-delay means for slowing return of said resistor to low value until said gap has substantially deionized.
  • an arc machining apparatus having a capacitor connected in shunt across a gap between an electrode and a workpiece, a power source, a charging circuit for said capacitor including a resistor, means for varying the magnitude of resistance value of said resistor, said means being operable automatically in response to current flow in the gap to regulate the value of said resistor in direct proportion thereto, and means for limiting the instantaneous voltage across the gap to a value substantially lower than that of the power source.
  • said automatically operable means includes time-delay means for slowing decrease in resistance value of said resistor after discharge across said gap until said gap has substantially deionized.
  • an arc machining apparatus having a capacitor connected in shunt across a gap between an electrode and a workpiece, a power source, a charging circuit for said capacitor including a resistor, means for varying the magnitude of resistance value of said resistor, said means being operable automatically in response to the difference of potential across said capacitor in inverse proportion relatively thereto, and means for limiting the instantaneous voltage across the gap to a value substantially lower than that of the power source.
  • an arc-machining apparatus having a condenser connected in shunt across a gap between an electrode and a workpiece, a charging circuit for said condenser, 21 triode vacuum tube connected in said charging circuit between said condenser and the power source with the anode of said tube connected to the positive side of said power supply and the cathode and the grid of said tube connected to one side of said condenser, and a network comprising a condenser and resistor in series connected in parallel with said first condenser.
  • a second triode tube is connected in the circuit with its anode connected to the grid of said first tube, its cathode connected to said network resistor remote from the network condenser and its grid connected to the junction between the network resistor and network condenser.
  • an electrode means for disposing said electrode in spaced relation to a workpiece such that intermittent electrical discharge across the gap therebetween will erode the workpiece, a first D. C. power source having the positive side thereof connected to the workpiece and the negative side thereof connected to the electrode, a condenser connected in shunt with said gap, a second D. C. power source connected in series with said first source, a vacuum tube connected in the positive lead of said second power source and control means operable automatically in response to discharge across said gap for rendering said tube substantially nonconductive upon discharge across said gap and conductive upon cessation of said discharge.
  • the combination of claim 12 including means connected in the circuit of said first power source for limiting the magnitude of the voltage across the gap in event of short circuit thereof to substantially that of said first power source.
  • control means comprises a triggering network connected in the grid circuit of said tube.
  • said triggering network comprises a second vacuum tube and control means therefor operable to render said second tube substantially non-conductive during charging of said condenser and conductive in response to discharge of said condenser.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
US459703A 1954-10-01 1954-10-01 Arc machining apparatus with periodic power control Expired - Lifetime US2804575A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL94837D NL94837C (en, 2012) 1954-10-01
NL199986D NL199986A (en, 2012) 1954-10-01
US459703A US2804575A (en) 1954-10-01 1954-10-01 Arc machining apparatus with periodic power control
CH334396D CH334396A (fr) 1954-10-01 1955-04-30 Dispositif à usiner par étincelles électriques
GB13358/55A GB788366A (en) 1954-10-01 1955-05-09 Improvements in and relating to electric arc machining apparatus
FR1133899D FR1133899A (fr) 1954-10-01 1955-05-25 Appareil de façonnage à l'arc à réglage périodique de l'énergie
DEE10795A DE1067546B (de) 1954-10-01 1955-05-28 Schaltanordnung zur Funkenerosion mit selbsttaetig veraenderbarem Ladewiderstand

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US459703A US2804575A (en) 1954-10-01 1954-10-01 Arc machining apparatus with periodic power control

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US2804575A true US2804575A (en) 1957-08-27

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US (1) US2804575A (en, 2012)
CH (1) CH334396A (en, 2012)
DE (1) DE1067546B (en, 2012)
FR (1) FR1133899A (en, 2012)
GB (1) GB788366A (en, 2012)
NL (2) NL94837C (en, 2012)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2871410A (en) * 1957-06-24 1959-01-27 Elox Corp Michigan Electrical discharge machining watchdog circuit
US2876386A (en) * 1956-04-12 1959-03-03 Sparcatron Ltd Electric disintegration of conductive materials
US2922078A (en) * 1957-08-07 1960-01-19 Soudure Elec Languepin Electric circuits for working and shaping materials by spark erosion
US2924751A (en) * 1957-02-07 1960-02-09 Inoue Kiyoshi Electric spark machining apparatus
US2951969A (en) * 1957-12-12 1960-09-06 Elox Corp Michigan Edm pulsing circuit
US2962630A (en) * 1959-04-13 1960-11-29 Elox Corp Michigan Power feed control
US2969482A (en) * 1956-10-08 1961-01-24 Centre Nat Rech Scient Machining systems making use of intermittent electrical discharges
US2979639A (en) * 1958-06-09 1961-04-11 Firth Sterling Inc Pilot pulse spark machining methods and apparatus
US3018411A (en) * 1960-05-03 1962-01-23 Robert S Webb Per pulse cut-off circuit
US3059150A (en) * 1959-08-07 1962-10-16 Gen Motors Corp Electric discharge machining apparatus
US3213319A (en) * 1960-05-02 1965-10-19 Inoue Kiyoshi Spark discharge machining apparatus with means for clearing short-circuit fusions
US3229159A (en) * 1960-05-16 1966-01-11 Elox Corp Michigan Superimposed high striking voltage circuit
US3231782A (en) * 1960-08-30 1966-01-25 Gen Motors Corp Electrical stock removal method and apparatus
US3286127A (en) * 1961-05-18 1966-11-15 Cincinnati Milling Machine Co Electric discharge machining apparatus with current control means
US3409756A (en) * 1965-01-27 1968-11-05 Union Carbide Corp Metal arc working
US3536880A (en) * 1964-03-14 1970-10-27 Charmilles Sa Ateliers Method and apparatus for machining through intermittent electric discharges
DE1440976B1 (de) * 1962-11-15 1972-07-27 Saint Gobain Elektroerosionsmaschine zur gleichzeitigen herstellung einer anzahl von loechern
USRE32855E (en) * 1980-02-26 1989-02-07 Inoue-Japax Research Incorporated Capacitor-type pulse generator for electrical discharge machining, especially for wire-cutting EDM

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE632237A (en, 2012) * 1960-03-29
DE1190594B (de) * 1961-08-12 1965-04-08 Deutsche Edelstahlwerke Ag Schaltungsanordnung fuer Funkenerosionsmaschinen
GB2002665B (en) * 1977-07-07 1982-03-03 Totsu K Electrically driven fastening appliance
US4516009A (en) * 1978-06-14 1985-05-07 Inoue-Japax Research Incorporated Capacitor-type HF power supply for electrical machining

Citations (5)

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Publication number Priority date Publication date Assignee Title
US2310092A (en) * 1935-05-17 1943-02-02 Westinghouse Electric & Mfg Co Electric discharge apparatus
US2483691A (en) * 1940-01-06 1949-10-04 Raytheon Mfg Co Condenser welding system
US2495301A (en) * 1950-01-24 Voltage regulator
US2515634A (en) * 1942-03-14 1950-07-18 Raytheon Mfg Co Electrical system
US2628330A (en) * 1951-11-14 1953-02-10 Method X Company Condenser-charging system for spark-cutting devices

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2614076A (en) * 1949-09-16 1952-10-14 Shell Dev Grease compositions

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2495301A (en) * 1950-01-24 Voltage regulator
US2310092A (en) * 1935-05-17 1943-02-02 Westinghouse Electric & Mfg Co Electric discharge apparatus
US2483691A (en) * 1940-01-06 1949-10-04 Raytheon Mfg Co Condenser welding system
US2515634A (en) * 1942-03-14 1950-07-18 Raytheon Mfg Co Electrical system
US2628330A (en) * 1951-11-14 1953-02-10 Method X Company Condenser-charging system for spark-cutting devices

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2876386A (en) * 1956-04-12 1959-03-03 Sparcatron Ltd Electric disintegration of conductive materials
US2969482A (en) * 1956-10-08 1961-01-24 Centre Nat Rech Scient Machining systems making use of intermittent electrical discharges
US2924751A (en) * 1957-02-07 1960-02-09 Inoue Kiyoshi Electric spark machining apparatus
US2871410A (en) * 1957-06-24 1959-01-27 Elox Corp Michigan Electrical discharge machining watchdog circuit
US2922078A (en) * 1957-08-07 1960-01-19 Soudure Elec Languepin Electric circuits for working and shaping materials by spark erosion
US2951969A (en) * 1957-12-12 1960-09-06 Elox Corp Michigan Edm pulsing circuit
US2979639A (en) * 1958-06-09 1961-04-11 Firth Sterling Inc Pilot pulse spark machining methods and apparatus
US2962630A (en) * 1959-04-13 1960-11-29 Elox Corp Michigan Power feed control
US3059150A (en) * 1959-08-07 1962-10-16 Gen Motors Corp Electric discharge machining apparatus
US3213319A (en) * 1960-05-02 1965-10-19 Inoue Kiyoshi Spark discharge machining apparatus with means for clearing short-circuit fusions
US3018411A (en) * 1960-05-03 1962-01-23 Robert S Webb Per pulse cut-off circuit
US3229159A (en) * 1960-05-16 1966-01-11 Elox Corp Michigan Superimposed high striking voltage circuit
US3231782A (en) * 1960-08-30 1966-01-25 Gen Motors Corp Electrical stock removal method and apparatus
US3286127A (en) * 1961-05-18 1966-11-15 Cincinnati Milling Machine Co Electric discharge machining apparatus with current control means
DE1440976B1 (de) * 1962-11-15 1972-07-27 Saint Gobain Elektroerosionsmaschine zur gleichzeitigen herstellung einer anzahl von loechern
US3536880A (en) * 1964-03-14 1970-10-27 Charmilles Sa Ateliers Method and apparatus for machining through intermittent electric discharges
US3409756A (en) * 1965-01-27 1968-11-05 Union Carbide Corp Metal arc working
USRE32855E (en) * 1980-02-26 1989-02-07 Inoue-Japax Research Incorporated Capacitor-type pulse generator for electrical discharge machining, especially for wire-cutting EDM

Also Published As

Publication number Publication date
NL199986A (en, 2012)
DE1067546B (de) 1959-10-22
CH334396A (fr) 1958-11-30
FR1133899A (fr) 1957-04-03
NL94837C (en, 2012)
GB788366A (en) 1958-01-02

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