Abstract: A discharge detection device of the present invention is configured to be capable of detecting a discharge phenomenon via wiring, including: a noise detection section electrically connected to the wiring and configured to allow a noise component generated by the discharge phenomenon to be input via the wiring and configured to output the noise component if the noise component has a predetermined frequency or more; and an arithmetic section configured to determine whether a level of the noise component is high by comparing the level of the noise component with a threshold. The arithmetic section counts the number of occurrence of the discharge phenomenon if the level of the noise component is determined to be high, and performs a control process selected based on the number of occurrence of the discharge phenomenon.

Abstract: An insulation testing apparatus includes: a power unit having a first and second terminals; a switching unit switching between an electrical connected and disconnected states between the wire rods of respective phases and the core, and the first and second terminals; a discharge measurement unit measuring an amount of discharge produced between a first and second members electrically connected to the first and the second terminal, respectively; an insulation determination unit determines, based on the amount of discharge, whether the coating of the wire rods satisfies a predetermined quality regulation; and a control unit controlling the switching unit such that all of the wire rods and the core are electrically connected to the first or second terminals, while controlling the switching unit such that none of the wire rods nor the core is insulated with both of the first and second terminals.

Abstract: A power supply device for an electric discharge machine includes a current supply unit for supplying a pulsed current to an electrode gap and a current regeneration unit for regenerating the current. The current supply unit includes a DC power supply, a first switching element, and a second switching element. The current regeneration unit includes a capacitor arranged between a first connection point between an electrode and the first switching element and a second connection point between a workpiece and the second switching element, and a third switching element which is arranged between a third connection point between the first connection point and the DC power supply and a fourth connection point between the second connection point and the capacitor and which is turned on from the start of current regeneration until the current value reaches zero, whereby regeneration current fall time is reduced.

Abstract: A machine learning apparatus includes: a state observation unit that observes a characteristic shape, an adopted plan, and a determination result as state variables, the characteristic shape representing a shape of a part of a product of wire electric discharge machining, adjustment of machining conditions being deemed as necessary for the part of the product, the adopted plan being an adjustment method selected from among one or more adjustment methods for adjusting the machining conditions to improve machining performance for the part indicated by the characteristic shape, the determination result indicating whether implementation of the adopted plan is effective in improving machining performance for the part corresponding to the characteristic shape; and a learning unit that learns the machining condition adjustment method according to a data set created based on the state variables.

Abstract: A power tool includes a motor, a rectifier circuit, and a driver circuit. An input terminal of the rectifier circuit is connected to a power module, an output terminal is connected to a direct current bus, an input terminal of the driver circuit is connected to the direct current bus, an output terminal is connected to the motor, and a bus capacitor is connected between a high voltage terminal and a low voltage terminal of the direct current bus. A first protection circuit is connected to the input terminal of the rectifier circuit and a second protection circuit is connected in parallel to two terminals of the bus capacitor. The first protection circuit is configured to absorb an overvoltage signal on an input side of the rectifier circuit. The second protection circuit is configured to absorb an overvoltage signal of the direct current bus.

Abstract: A machine learning apparatus for learning a correction parameter used in correction of a command value that controls a motor in a motor drive system including a plurality of kinds of correction functions includes: a state observation unit that observes, as a state variable, each of a feature calculated on the basis of drive data and the kind of any of the correction functions of the motor drive system and the correction parameter; and a learning unit that learns the correction parameter for each of the correction functions according to a training data set created on the basis of the state variable.

Abstract: A system for evaluating a bond includes first and second electrodes. A dielectric material layer is positioned at least partially between the first and second electrodes. A power source is connected to the first and second electrodes. The power source is configured to cause the first and second electrodes to generate an electrical arc. The electrical arc is configured to at least partially ablate a sacrificial material layer to generate a plasma.

Abstract: A power supply device for wire electric discharge machining includes: a first DC power supply; first switching elements between the first DC power supply and a machining gap; a second DC power supply; a second switching element between the second DC power supply and the machining gap; and a pulse generator controlling the first and second switching elements. The pulse generator is configured so that, in order to generate an electric discharge in the machining gap, the second switching element is switched on and the voltage of the second DC power supply is applied to the machining gap; the first switching element is switched on intermittently at a predetermined frequency in response to an electric discharge generation detection signal, and a series of current pulses is fed to the machining gap. The feeding of the series of current pulses is discontinued when the current pulses don't reach a reference current.

Abstract: A downhole drilling system is disclosed. The downhole drilling system may include a pulse-generating circuit electrically coupled to a power source configured to provide an alternating current at a frequency and an input voltage, the pulse-generating circuit comprising an input stage circuit electrically coupled to the power source, the input stage circuit configured to control the alternating current in the pulse-generating circuit; a transformer circuit electrically coupled to the input stage circuit, the transformer circuit comprising an open-core transformer configured to generate an output voltage higher than the input voltage; and an output stage circuit electrically coupled to the transformer circuit, the output stage circuit configured to store energy for an electric pulse; and a drill bit including a first electrode and a second electrode electrically coupled to the output stage circuit to receive the electric pulse from the pulse-generating circuit.

Abstract: A method of polishing a surface of an object disposed within a gas chamber is provided. The method includes filling the gas chamber with a discharging medium to a predefined pressure, applying a voltage between an electrode and the surface, calibrating a height of the electrode relative to the surface so as to establish electrical breakdown threshold criteria, and scanning the electrode with respect to the surface so as to sequentially position the electrode over a plurality of locations on the surface, each location characterized by a surface error. When a respective location in the plurality of locations has a surface error that meets the electrical breakdown threshold criteria, electrical breakdown occurs, whereby the electrical breakdown results in a discharging pulse that polishes the surface.

Abstract: A method for treating a tension member in the production of a belt. The belt includes at least a belt body made of a polymer material having elastic properties, a cover layer as a belt backing, and a substructure having a force-transmission zone. The tension member has a ribbed design and is embedded in the belt body. The tension member is treated with an overall treatment mixture which forms a cross-linked polymer that on the one hand enters into a mechanical connection with the tension member and on the other hand forms an adhesive connection with the belt body.

Abstract: A method for charging an auxiliary voltage source of a boat having an electric drive that is powered by a main voltage source of the boat, the auxiliary voltage source providing power for at least one additional component, is described. A protection and/or control circuit is electrically connected to the main voltage source via a DC-to-DC converter configured for power supply, and to the auxiliary voltage source via a switch or a reverse blocking valve. The auxiliary voltage source is charged via the main voltage source.

Abstract: An electric discharge machining system is provided which distinguishes an abnormal discharge caused by an immediate discharge and an abnormal discharge caused not by the immediate discharge to suitably control in each case.

Abstract: A method of polishing a surface of an object disposed within a gas chamber is provided. The method includes filling the gas chamber with a discharging medium to a predefined pressure, applying a voltage between an electrode and the surface, calibrating a height of the electrode relative to the surface so as to establish electrical breakdown threshold criteria, and scanning the electrode with respect to the surface so as to sequentially position the electrode over a plurality of locations on the surface, each location characterized by a surface error. When a respective location in the plurality of locations has a surface error that meets the electrical breakdown threshold criteria, electrical breakdown occurs, whereby the electrical breakdown results in a discharging pulse that polishes the surface.

Abstract: Supply energy arrangement comprising an input (E) to which an energy source (Q) is coupled, an output (A) for connection of a load (V), a first energy storage device (E1) that is coupled to the input (E) and the output (A), a second energy storage device (E2) that is coupled to the output (A) and, via a switching means (S), to the input (E), and a control circuit (C) that controls the switching means (S) in such a manner that the switching means (S) connects/disconnects the second energy storage device (E2) to/from the input (E) according to the energy level of the first energy storage device (E1).

Abstract: A discharge surface treatment apparatus generates a pulsed discharge between poles, that is, between a discharge electrode and a workpiece, and the discharge electrode is obtained by compression-molding of any one of a metal powder, a powder of a metal compound, and a powder of ceramics or a mixture thereof. The apparatus forms a film made of an electrode material or the like on a workpiece surface by thermal energy due to the discharge. The apparatus includes: a capacitor that is connected to any one of the discharge electrode and the workpiece at one end; and a parallel circuit of a resistor and a diode, which is provided between another one of the discharge electrode and the workpiece and another end of the capacitor via a connection line.

Abstract: The present invention is equipped with a series circuit that includes a DC power supply, switching elements and a diode for supplying DC or AC current pulses to a machining gap between a machining electrode and a workpiece, diodes that regulate a direction of the current flow to one direction, and a control unit that controls the switching elements. When the control unit generates a current pulse having a triangular waveform by an inductance that is present in the series circuit, the control unit controls the switching elements in order that a current-pulse time ratio that is a ratio between the non-current time and the current continuation time in the current pulse is equal to or lower than 1/5.

Abstract: An apparatus, method and computer program, the apparatus comprising: communication circuitry configured to drive, on a first occasion, a first transition of a first electrical parameter on an electrical interface to another apparatus; determination circuitry configured to determine feedback information dependent upon a measured electrical parameter on the electrical interface; and control circuitry configured to use the determined feedback information to control the power output of the communication circuitry to achieve, on a second occasion subsequent to the first occasion, the first transition of the first electrical parameter on the electrical interface within a threshold time period.

Abstract: A power supply device for a wire electric discharge machine is provided with a main DC power source and an auxiliary DC power source with variable voltage. While first pulses are being output, a voltage from the main DC power source is applied to a machining gap between a wire electrode and a workpiece. While second pulses are being output with the output of the first pulses stopped, inductive energy stored by an inductance in a circuit is passed through the gap, and a voltage corresponding to a peak current value provided by the main DC power source is applied to the gap by the auxiliary DC power source. When the output of the second pulses is stopped, the inductive energy is returned to the main DC power source.

Abstract: A high frequency power source configured to provide a variable voltage output is described such as for use in welding systems. The high frequency power source charges a capacitive storage device. A transformer having a primary winding coupled to the output of the high frequency power source and establishing a resonant frequency signal with the capacitive storage device, and a secondary winding coupled to the welding power supply, superimposes the resonant frequency signals onto the welding power signal of the welding power supply during periods of the resonant rings. By varying the voltage output from the high frequency power source, the high frequency energy delivered to the welding torch can be optimized for a variety of welding applications.

Abstract: The invention relates to a protective circuit (10) in a screen wiper drive (1), consisting of a parallel circuit having two circuit elements (16, 17), wherein one circuit element (16) consists of a capacitor (18) and the other circuit element (17) consists of a series-connection of a diode (19) and a Zener diode (20), wherein the forward direction of the diode (19) and the Zener diode (20) is different and the Zener diode (20) inhibits in the direction of a plus pole.

Abstract: The invention relates to a method for electrical discharge machining of workpieces by electrical discharge pulses generated by a power module of an electrical discharge machine. The invention is characterized in that firstly the discharge voltage of a number N1 of electrical discharge pulses is acquired and stored, secondly a front discharge voltage (63) is determined out of this amount of N1 acquired discharge voltages and thirdly, the voltage Uhps (64) of the electrical discharge pulses produced by the power module for machining the workpiece (17) is adjusted in function of the determined front discharge voltage (63).

Abstract: A wire electric-discharge machining device includes a control unit that selects a cutting wire to which a pulse voltage is applied by a pulse-voltage generation unit on a basis of an angle formed between an end face of a workpiece and a plane including a plurality of cutting wires, which are not parallel to the end face, an interval between parallel cutting wires, and a relative distance between the cutting wires and the workpiece. A drive unit drives a workpiece in a direction not vertical to the plane including the cutting wires, and the workpiece is cut by electric-discharge machining by applying a pulse voltage.

Abstract: A device and method for the removal of a metal-sheath layer from a metal-sheathed structure using capacitive discharge in conjunction with step-up and step-down transformers to create a low voltage, high current pulse to remove a selected portion of the metal-sheath layer from the metal-sheathed structure.

Abstract: A switching element operates to be turned on or off at a frequency in the order of megahertz. A reactor supplies a resonance current generated by resonance of the reactor with a floating capacitance between electrodes to between the electrodes. The resonance current does not flow in a direct-current power supply. By turning a capacitor and a floating inductance into a serial resonant state, the reactor ideally supplies the resonance current to between the electrodes without influence of the floating inductance. A high-frequency voltage asymmetric in positive and negative polarities is applied to between the electrodes and a current pulse can be made into a short pulse. Therefore, finish machining with high surface roughness can be performed.

Abstract: In carrying out electric discharge machining of a graphite or carbon-composite workpiece by a wire electric discharge machine, a voltage lower than that used in machining a metal workpiece by the wire electric discharge machine is supplied to a machining gap. Further, the peak value and the pulse width of a total discharge current flowing from a power supply device for electric discharge machining to a wire electrode are adjusted within ranges of 30 to 150 amperes and 0.3 to 6.4 microseconds, respectively.

Abstract: A power supply device comprises a DC power supply (12), a current sensor (14) for detecting gap current (Igap) flowing through the machining gap, a first switching element (16) connected in series between the DC power supply and the tool electrode (2), a first reverse current prevention diode (22) connected in parallel with the DC power supply and connected in series with the first switching element (16), a second switching element (18) connected in series between the DC power supply and the workpiece (3), a second reverse current prevention diode (24) connected in parallel with the DC power supply and connected in series with the second switching element (18), and a pulse controller (20) for controlling the first and second switching elements in response to gap current (Igap). From a first time (t1) when electric discharge is generated across the machining gap, until a second time (t2) when the gap current reaches the peak current during the ON time, both of the first and second switching elements are on.

Abstract: In a wire electrical discharge machining apparatus, an upper main-discharge power supply is connected between an upper conducting terminal and a workpiece using an upper main-feeder line capable of configuring outward and homeward paths, and a lower main-discharge power supply is connected between a lower conducting terminal and the workpiece using a lower main-feeder line capable of configuring outward and homeward paths. Moreover, a sub-discharge power supply is connected between the upper conducting terminal and the workpiece and between the lower conducting terminal and the workpiece using an upper and a lower sub-feeder lines that have higher impedances than the impedances of the upper and the lower main-feeder lines and can configure outward and homeward paths.

Abstract: In a torque motor driving device for wire cut electrical discharge machines, a voltage waveform rectified by a full-wave rectifying circuit, not using a high-capacitance electrolytic capacitor, is applied as an AC voltage to a single-phase torque motor by a bridge circuit including semiconductor switches. A PWM signal whose duty is adjusted so that the current flowing through the torque motor matches an instructed value is generated and the generated PWM signal is used for the operation of the bridge circuit.

Abstract: A power-supply control device includes a high-frequency component detecting unit, a machining voltage level detecting device, a no-load time detecting device, and a pulse control device. The high-frequency component detecting unit detects a high-frequency component of discharge voltage at a machining gap. The machining voltage level detecting device detects a discharge voltage level at the machining gap. The no-load time detecting device detects delay time of discharge of the discharge voltage at the machining gap. The high-frequency component is compared with a reference value to obtain a first comparison result. The discharge voltage level is compared with a reference level to obtain a second comparison result. The pulse control device controls pulse off time based on the first comparison result and the detected delay time, and cuts off a discharge pulse based on the second comparison result.

Abstract: A discharge pulse control device cuts off a pulse width of the a discharge pulse being produced in a machining gap when a comparison result of a voltage level comparator indicates abnormal electrical discharge. Upon detection of abnormal electrical discharge based on comparison results of a high-frequency component comparator and the voltage level comparator, a quiescent period control unit constructed from a discharge pulse diagnosis device, a first pulse counter, a second pulse counter, and a quiescent pulse control device performs change setting of the quiescent period at the time of occurrence of abnormal electrical discharge and sends that information to the discharge pulse control device. Subsequently, the discharge pulse control device performs change control of the quiescent period at the time of occurrence of abnormal electrical discharge so that the discharge pulse and the quiescent time are optimally controlled.

Abstract: An electric discharge machining device that performs processing by applying a voltage pulse to space between the processing electrode and the workpiece and suitably switching the polarity of the voltage pulse attains both desired processing accuracy and desired controllability. The electric discharge machining device is provided with the first to fourth switching elements. The controlling unit that controls these switching elements, when setting a period time in which the first switching element is turned on, a period of time in which the fourth switching element is in an on-state in the same period, and, when setting a period time in which the second switching element is turned on, a period of time in which the third switching element is in an on-state in the same period so that a desired voltage pulse is applied to the space between the processing electrode and the workpiece.

Abstract: In a waveform of switching signals, which is output from a full-bridge circuit formed of four switching elements, includes a normal polarity pulse group and a reversed polarity pulse group for controlling an output timing of voltage pulses. A duty cycle of the normal polarity pulse group containing a plurality of normal polarity pulses, which apply a positive power-supply polarity to a workpiece and apply a negative power-supply polarity to a machining-purpose electrode, is configured so as to be different from a duty cycle of the reversed polarity pulse group containing a plurality of reversed polarity pulses, which apply a negative power-supply polarity to the workpiece and apply a positive power-supply polarity to the machining-purpose electrode.

Abstract: An electrode for machining a pattern in a workpiece has a conductive body with a lattice of closed cells and a plurality of open cells. The open cells are positioned at an edge of the lattice of closed cells. The closed cells are defined by interconnected webs, and the open cells are defined by fins extending from the interconnected webs. A thickness of the fins is less than a thickness of the webs. In use, the electrode is positioned at a plurality of locations on the workpiece, such that a position of the fins of the electrode at each location overlaps a position of the fins of the electrode at an adjacent location. The pattern is formed at each of the plurality of locations by passing electrical charges repeatedly between the electrode and the workpiece and advancing the electrode into the workpiece.

Abstract: In an electric discharge machining, in order to reduce damage of an object to be machined and an electrode and to achieve machining velocity enhancement and reduction of electrode wear amount by appropriately controlling a short-circuit current that flows when the electrode and the object to be machined are short-circuited, an electric-discharge-machining power supply apparatus for machining an object to be machined by interrupting every predetermined time period pulse trains that are turned on and off at predetermined timing, to supply electric power to a machining gap between a machining electrode (2) and the object (3) to be machined includes: a short circuit detecting means (11) for detecting a short circuit at the machining gap between the machining electrode (2) and the object (3) to be machined; and a pulse halting means (12) for, when the short circuit detecting means (11) detects a short circuit occurrence at the machining gap, halting generation of particular pulses in the pulse train so as to halt

Abstract: An EDM die sinking device includes a tank for holding a fluid, and at least one electrode in the tank having a shape for imparting to a first portion of a workpiece. A workpiece holder positions the workpiece at least partially immersed in the fluid and alternately moves the workpiece between an inoperable position and a first operable position of the first electrode at which electric discharge machining occurs on the first portion. A pulse generator creates an electric discharge between the first portion and the first electrode to remove material from the first portion in response to the workpiece being in the first operable position. Movement of the workpiece from the electrode flushes particle containing fluid away from the workpiece and the electrode. A segmented electrode includes a separate pulse generator for each segment may also be employed.

Abstract: The present invention is a device for coating surfaces of metallic work pieces with an electrically conductive material by employing short duration high current packets of pulses in which the work piece forms the cathode and the consumable coating material forms the anode, which are connected to a generator for generating pulses by charging and discharging a bank of capacitors using a MOSFET. The invention is also a device for controlling the on and off time of a metal oxide semiconductor field effect transistor (MOSFET).

Abstract: A power-supply control device includes a high-frequency component detecting unit, a machining voltage level detecting device, and a pulse control device. The high-frequency component detecting unit detects a high-frequency component of discharge voltage at a machining gap. The machining voltage level detecting device detects a discharge voltage level at the machining gap. The high-frequency component is compared with a reference high-frequency component to obtain a first comparison result. The discharge voltage level is compared with a reference voltage level to obtain a second comparison result. The pulse control device controls pulse off time based on the first comparison result, and cuts off a discharge pulse based on the second comparison result.

Abstract: A method for electrical discharge machining a workpiece includes dividing machining time into a sensing interval during which reference values are captured from machining pulses and into a machining interval during which no reference values are captured. The sensing interval includes either a first sensing interval after implementation of a jump motion of the electrode in the working gap or a second sensing interval after application of an extended pause time to at least some of the machining pulses. The extended pause time is longer than a pause time of other ones of the machining pulses. The method also includes sensing an electrical parameter of a current machining pulse and deriving at least one characteristic value from the sensed electrical parameter. The method further includes comparing characteristic value to at least one of the captured reference values and initiating an action depending on a result of the comparison.

Abstract: The invention relates to a method and a generator for generating a time sequence of discharge pulses separated from each other by pulse pauses for electrical discharge machining. At least two pulse capacitors are discharged each in the form of a partial pulse into the spark gap for forming together a discharge pulse. A discharge pulse having a predetermined waveform is selected from a plurality of discharge pulses having differing predetermined waveforms. The discharge of the at least two pulse capacitors is controlled such that the selected discharge pulse is generated with the predetermined waveform.

Abstract: An apparatus and method for adapting a CNC milling machine for electroerosion machining. The apparatus includes a tubular electrode on the distal end of an adapter shaft. A tool holder on the proximal end of the adapter shaft is mountable in the chuck of a cutter spindle in the milling machine. The adapter shaft is rotatably mounted within a bearing and an electrical brush contact subassembly, both of which are supported by a bracket. The bracket is attached to the milling machine but insulates it from the tool electrode. The bearing supports the adapter shaft in alignment with the CNC spindle. An electrical power supply energizes the electrode and the workpiece for electroerosion in a gap between them. Electrolyte is circulated through the spinning tool electrode during operation. The CNC computer is configured to operate the machine, power supply, and electrolyte flow for electroerosion machining.

Abstract: The invention relates to a method and generator for generating a time sequence of EDM pulses having a predefined ignition voltage for electrical discharge machining. An AC voltage is generated from a DC voltage, furnished by a bipolar current source. The AC voltage is applied to an isolating transformer disposed between the bipolar current source and the spark gap. A first pulse capacitor is charged by the bipolar current source to a voltage corresponding to the ignition voltage. The ignition voltage provided by the isolating transformer is switched with a selected polarity to the spark gap.

Abstract: The invention relates to a method and a generator for generating a time sequence of discharge pulses for EDM machining wherein a pulse capacitor (22) for generating the discharge pulse is charged with a charging voltage (U_chrg) and then discharged into the spark gap. The pulse capacitor (22) after being discharged is recharged with a charging voltage (U_chrg) having the same polarity as that of the residual voltage (U_end) remaining at the pulse capacitor (22) after its discharge. Thereafter, the pulse capacitor (22) is discharged with a discharge pulse into the spark gap, wherein the polarity of the discharge pulse is independent of the polarity of the charging voltage (U_chrg) at the pulse capacitor (22) after its recharge.

Abstract: The invention relates to a method for producing a thread in a bore (2) by remote automatic machining characterized in that the method consists in introducing into the bore (2) an electrode (11) provided with a thread (20) whose shape and dimensions are pre-determined according to the shape and dimensions of an inside thread to be produced, in machining the internal threads by electroerosion displacing the electrode (11) in an orbital manner in the bore (2) according to a predetermined number of operations and in adjusting the machining parameters according to each operation. A device for carrying out said method is also disclosed.

Abstract: In order to obtain an electric-discharge-machining power supply apparatus that can flow discharge current pulses through the machining gap uniformly and efficiently, and can realize reduction of the amount of electrode wear in machining in the alternate current pulse system, in an electric-discharge-machining power supply apparatus (2) for applying electric-discharge-machining pulse voltage to a machining gap between a machining electrode (8) and an object (9) to be machined, wherein a circuit (22) composed of a parallel connection of a rectifying element (24) and a resistive element (23) is inserted in series along a wiring path extending from an electric-discharge pulse generating unit (6) to the machining gap, and the rectifying element (23) is so connected as to cause machining pulse currents to flow in an intended direction during the electric discharge generation.

Abstract: Apparatus for forming metallic crystalline nanoparticles includes a dispersion medium, first and second electrodes separated from each other by a predetermined span and being inserted into the dispersion medium. The electrodes are connected to a supply of electrical current at a preselected voltage. A filament is in contact with the two electrodes and is also inserted into the dispersion medium. Upon a first switch connecting the supply of electrical current to the electrodes, a pulsed current passes through the electrodes and the filament at a voltage preselected to disintegrate the filament into fragments, but does not create plasma from the filament.

Abstract: An apparatus and a method of generating machining pulses for electrical discharge machining by discharge of at least one line applying a voltage to a working gap formed between a machining electrode and a workpiece, including the steps of: charging the line via a first charging circuit by a voltage source, discharging the line after ignition of the spark gap directly via a diode, without impedance matching, at the working gap, and recharging the line after a predefined pulse-off time.

Abstract: A method for machining a workpiece which includes a conductor which carries a time-variable current along its longitudinal axis and is guided by an upper guide and a lower guide. A magnetic field is produced between the guides, the upper guide being located at a distance above the magnetic field and the lower guide at a distance below the magnetic field.

Abstract: An electric discharge machining apparatus comprises a power supply (5) for applying a voltage to a work gap formed between a tool electrode (E) and the workpiece (W) and a motor (7) that moves the tool electrode relative to the workpiece. An electric discharges counter (45) counts a number of electric discharge occurrences within a specified period (Td1) and generating a first count. A gap controller (48) multiplies the first count by a gain to generate position command or speed command for motor drive. An inversion counter (42) counts a number of inversions of the gap voltage upwards or downwards within a second specified period (Td2) and generating a second count. An electric discharge discriminator (44) discriminates the occurrence of electric discharge when the second count reaches a set value.

Abstract: The invention relates to a method and device for electrical discharge machining (EDM) a workpiece by means of a train of machining pulses. During the machining time the machining pulses are applied to the working gap between workpiece and electrode, whereby an electrical parameter of the current machining pulse applied to the working gap is sensed, from which at least one characteristic value is derived. This is compared to a reference value, and depending on the result of the comparison, actions are initiated. The reference value is captured on the basis of at least one earlier machining pulse. The machining time is divided in time into sensing intervals during which reference values are captured from the applied machining pulses and into machining intervals during which no reference values are captured from the applied machining pulses.