Showing papers on "Electrical discharge machining published in 1986"

Electrical discharge machining electrode

Abstract: A wire electrode for a traveling wire EDM apparatus that comprises a copper clad steel core that is clad with a homogenous, outer brass layer using a classical bonding process. The copper clad steel core has a conductivity in the range of 50%-70% IACS (International Annealed Copper Standard) and the brass layer comprises 35%-50% by volume of the electrode. The brass layer comprises 65% copper and 35% zinc in an optimum construction. For a wire electrode having an overall diameter of 0.010 inches, the outer homogenous, brass layer is substantially 25 microns thick when the brass comprises 35% by volume of the wire and the copper clad steel core has a conductivity of 60% IACS and is contructed from AISI 10006 steel wire.

Graphite electrode construction and method of making

Abstract: Electrical Discharge Machining (EDM) utilizes electrodes made out of carbon, for example, in place of cutting tools. The shape of the electrode determines the shape of the part being machined. The EDM process wears down the carbon electrode cutting tool. By adhering fresh carbon material to the base of a carbon electrode as it wears down with a graphite and metallic powder-filled adhesive, the electrode can continue to be resurfaced indefinitely, thereby eliminating waste. In order to hold the carbon electrode more securely during initial shaping of the electrode, a metal base plate is used which is formed so that a portion of it fits into a cavity in the base of the carbon electrode. The carbon electrode is held fast to the metal base plate by countersunk bolts that engage threaded holds in the base plate. Flushing channels are provided through the metal base plate. Metal tooling clamps engage the metal base plate to hold it and the carbon electrode firmly against a tooling bed.

TW-EDM method and apparatus with a ferromagnetic wire electrode

Abstract: A traveling-wire electrical discharge machining method and apparatus in which a magnetic property of the traveling electrode wire is detected downstream of the cutting zone to indicate a disturbance of erosive electrical discharges from a predetermined normal mode in the cutting zone. The workpiece is a ferromagnetic material to provide a deposit of such material at a discharge site on the wire in the cutting zone and/or the wire is a ferrous material which preferably consists of 0.05 to 3% by weight one or more rare-earth element and the balance a steel material. The ferrous material may be present as a core wire having a layer of metal or alloy of higher conductivity.

Electric discharge machining power supply device

Abstract: PURPOSE:To prevent a decrease of accuracy on a machining surface and eliminate its electrolytic corrosion or the like by an electrolytic current, by applying a voltage pulse of both positive and negative polarities across a machining gap between a electrode and a work to be machine and setting average voltage across the machining gap to zero. CONSTITUTION:Resistance values R11, R12 of current limiting resistors 16, 17 are selected to a sufficiently large level as compared with a resistance value R2 of a resistor 19. A peak current value, fed from the second DC power supply 7 by turning on a semiconductor switching element 18, is in sufficiently high level as compared with a peak current value fed from the first DC power supply 3 through switching elements 12-15, causing the switching element 18 to supply an electric current, contributing to electric discharge machining, across electrodes. An average value in a waveform of voltage between the electrodes is set to zero, but the current flowing between the electrodes never generates an average value of zero, and a device allows the currents to flow from a work 2 to be machined to the electrode 1, accurately machining the work.

Cut wire for electrical discharge machining

Abstract: An improved cut wire used as an electrode in electrical discharge machining which has higher tensile strength at high temperatures. It is a composite wire having a core of stainless steel and a covering layer of copper or copper alloy provided around the core. The diameter and the tensile strength of the cut wire and the percentage of the sectional area of the core to that of the entire cut wire are important parameters in the composite wire.

Wire guide for electric discharge wire cutting

Abstract: A wire guide for wire electrode type electrical discharge machining be employed both for taper machining and for non-taper machining with high accuracy, regardless of the magnitude of the taper angle. The guide can be readily connected to (threaded with) a wire electrode and can be employed in an electrical discharge machining apparatus having an automatic wire connecting (threading) system. The wire guide is provided an arc-shaped guide arranged at a location concentric with a wire electrode for electrical discharge machining, a three-point-supporting guide arranged closely to the arc-shaped guide along the wire electrode for allowing the wire electrode to pass therethrough, and an external tube member for holding the arc-shaped guide and the three-point-supporting guide therein. The guide has a center hole for allowing the wire electrode to pass therethrough and a cooling liquid supply hole for supplying a cooling liquid for cooling the wire electrode.

High speed electrical discharge machining by redressing high resolution graphite electrodes

Abstract: An EDM apparatus for high speed machining of a workpiece and redressing of a graphite electrode by an ultrasonic machining tool or a total form machining tool. When the electrode becomes worn the workpiece clamped on a table (1) is shifted away by a slideway mechanism (4) so that a master on another table (2) confronts the worn electrode. The electrode is then redressed and the workpiece is slid back into position by the slideway mechanism (4) for more machining by the redressed electrode.

Method of making powders by electro-discharge machining in a cryogenic dielectric

Abstract: Powders, and particularly metallic powders, are produced by electro-discharge machining of electrically conductive electrodes made of the desired materials in a cryogenic dielectric. When a sufficient quantity of powder has been produced, the cryogenic dielectric is allowed to evaporate, leaving the powders available for recovery. Powders formed by this process have unique microstructures, and thus unique properties, as a result of rapid cooling in the cryogenic medium. By using an inert cryogenic dielectric, such as argon, powders uncontaminated by the dielectric are produced.

EDM wire electrode

Abstract: An improved electrical discharge machining electrode permitting increased cutting speed of the metal workpiece being machined and which improves the operation of the electrical discharge machining equipment in other respects. The improvement is atrributable to an adherent carbon surface coating deposited on an electrically conductive metal wire length which serves to transfer energy efficiently to the workpiece from the spark discharge as well as enhance the flushing of materials removed by said discharge during the machining operation. The method and apparatus for employment of said improved electrode is also described.

Wire cut electric discharge machining device

Abstract: PURPOSE: To shorten the selection time of the optimum machining condition necessary for machining by providing a machining condition memory unit associatively storing machining conditions, works, and work conditions, a machining condition setting/display unit, and a machining condition compiling/ registering unit. CONSTITUTION: Electrical and mechanical machining condition is selected and set in a machining condition setting/display unit 18 by an input switch 22 via a logic circuit 17 and is stored in a machining condition table 24. Corresponding work material, plate thickness, machined surface roughness, and wire electrode diameter are likewise stored in a work condition table 25. Next, both condition data are compiled by a machining condition compiling/registering unit 23 and are stored in a machining condition memory unit 19 as the machining condition data in one package, and when completed, the machining condition setting/ display unit 18 sets the data in a display table 20 for display on a CRT display unit 21. Many data are thus registered, and if the electrode and work condition used are set on the CRT display unit 21 during machining, then the relevent machining conditions are displayed, thus the optimum condition is selected by confirming them. COPYRIGHT: (C)1987,JPO&Japio

Manufacture of electric discharge machining electrode for forming honeycomb die

Abstract: PURPOSE: To make it possible to cut forming grooves in a honeycomb die machining electrode with a high degree of accuracy, by carrying out a prefinishing step of cutting grooves in a predetermined part of an electrode block formed in a predetermined shape, and a finishing step of setting a plate thickness to planar projection electrode parts. CONSTITUTION: Parallel grooves or first prefinishing groves 4, 4... are previously formed at predetermined pitches P 1 in an electrode block 1' which is formed from a graphite material by forming the latter into a block-like shape. The width d 1 of the grooves 4 and the pictures P 1 are previously determined in accordance with the shape and dimensions of a honeycomb body, and the depth of the grooves corresponds to the height H of projection electrode parts 3. Then second prefinishing grooves 5, 5... having predetermined pitches P 2 and a predetermined width of d 2 are formed in a zigzag pattern, orthogonal to the first prefinishing grooves 4, 4. After completion of the prefinishing step, a finishing step of cutting finishing grooves 6, 6... having predetermined pictures P 3 and a predetermined width d 3 , orthogonal to the first prefinishing grooves 4, 4 is carried out to produce an electrode. Thus, it is possible to simply produce a honeycomb forming electric discharge machining electrode of the unit structure with a high degree of accuracy. COPYRIGHT: (C)1988,JPO&Japio

Electrode for electric discharge machining and method for producing the same

Abstract: An electrode for electric discharge machining wherein at least a part of the surface of the electrode is coated with a non-single crystalline insulator to prevent undesirable electric discharge between the electrode and a workpiece. The electrode may also have a coating of a buffer material formed from a metal having a small thermal expansion coefficient or from an amorphous material, in which case the exterior coat is a hard insulator with a Vickers hardness of at least 1000 coated on the buffer. A process for the production of these electrodes using plasma discharge methods is also described.

Electric discharge machining for electric insulator

Abstract: PURPOSE: To easily perform the electric discharge machining of ceramic or the like by performing the electric discharge machining is formation of electric conductor on the surface of the electric insulator and forming the conductive layer at high temperature with the carbon and conductive powder in the machining liquid and then repeating the electric discharge machining and the formation of the conductive layer. CONSTITUTION: On the surface of an electric insulator 1 to be machined, a conductive layer 2 is formed by the frame coating, evaporation, plating or the like of copper, iron or the like and the electric discharge machining is started with the supply of the machining liquid such as kerosene between the same and a machining electrode 3. First, the conductive layer 2 is machined so that the electric insulator 1 facing to the conductive layer 2 is exposed. Then machining powder and carbon in the machining liquid are sticked to the electric insulator 1 and further penetrated thereinto and the new conductive layer 4 is formed at the high temperature caused by the electric discharge machining. The electric insulator such as ceramic is machined by repeating the electric discharge machining and the formation of the conductive layer 4. Therefore it is possible to easily perform the electric discharge machining of the electric insulator such as ceramics. COPYRIGHT: (C)1988,JPO&Japio

Electric discharge machining apparatus of wire-cutting type.

Abstract: An electric discharge machining apparatus of the wire-cutting type is equipped with a wire cutting unit between an upper wire guide member and a work table, the wire cutting unit being allowed to move in a horizontal direction to traverse a wire electrode (W) which downwardly extends with respect to the upper wire guide member from a wire passage of the upper wire guide member. The wire cutting unit comprises a base block (55), and a movable block (56) which can approach or separate away from the base block to define a slit (60) that can be opened or closed relative thereto and to define a nozzle hole (61). The slit extends in a horizontal direction in which the wire cutting unit moves to accept the wire electrode. The nozzle hole can be connected to the lower end of wire passage of the upper wire guide member, and is so formed as to inject a liquid toward the wire passage of the lower wire guide member, the liquid being supplied into the wire passage of the upper wire guide member. The wire cutting unit has a wire detector (66) for detecting an end of the wire electrode between the base block and movable block, and has wire cutting means (62) for cutting the wire electrode between the base block and the movable block.

Power source apparatus for wire-cut electric discharge machining

Abstract: PURPOSE:To prevent the elution of the metal and alloy which possess easy electrolytic elution characteristic by applying the negative-electrode voltage pulses in the repose time between the positive-electrode voltage pulses and setting the average working voltage to 0V or less. CONSTITUTION:A monostable circuit 10 generates output pulses from the starting-up of the output pulses of an oscillator 9, and a switching element 5 is turned-ON for the time width. The positive-electrode voltage pulses are applied between a wire electrode 1 and a workpiece 2 by a positive-electrode power source 3. When the output pulses (b) of the monostable circuit 10 become- OFF, the output of a reversal circuit 11 becomes-ON, and the output pulses of a monostable circuit 12 are outputted from the starting-up. Therefore, a switching element 8 is turned-ON, and the negative-electrode voltage pulses are applied between the wire electrode 1 and the workpiece 2 by a negative- electrode power source 6.

Power supplying device for electrical discharge machining

Abstract: PURPOSE:To prevent or reduce elusion of metal of highly electrolytic elusion type in material for electrode construction by applying voltage pulse of inverse polarity or controlling discharge when discharging of machining clearance is not proper. CONSTITUTION:When output e of a voltage detecting circuit 7 is made ON at the point where output pulse c of a one-shot multi-vibrator circuit 10 becomes OFF, a flip-flop circuit 14 is set. Output pulse g is applied to one of input terminals of a gate circuit 19 and output pulse b' of an inverse turn circuit 6 is begun to be applied to the other input terminal, and output pulse h of the circuit 19 is output and output i of the one-shot multivibrator circuit 18 is made ON and a switching element 17 is also made ON, then voltage pulse of inverse polarity is applied between an electrode 1 and a work to be machined 2.

Electrode guide unit for wire-cut electric discharge machining

Abstract: PURPOSE:To obtain an excellent and non-interfered machining liquid column by providing the captioned unit with an overflowed liquid reservoir having an inlet for accepting the machining liquid flowing down from the above of a wire electrode guide and an overflowed liquid discharged outlet at the side face. CONSTITUTION:The machining liquid entered from an inlet 20 is joined to the machining liquid flowed down from a through hole 24b, and jetted from a nozzle 30a to a wire electrode 14 forming a liquid column up to a machining section 100. And, on the clamping body 28 of an electrode guide unit, an opening for accepting the machining liquid and an overflowed liquid reservoir 34 having an outlet 36 at the side face are formed in a body. More than a specified amount of the machining liquid is, therefore, discharged from the outlet 36 and moreover, being not interfered with the discharged machining liquid, the machining liquid of a machining section remains orderly obtaining excellent cooling effect and also being free from occurrence of abnormal electrical discharging caused by a shortage of machining liquid and occurrence of wire electrode cutting.

Wire feed mechanism of wire electric discharge machine

Abstract: A wire feed mechanism of a wire electric discharge machine, which rewinds a wire electrode (P), that is broken during electric discharge machining, by a wire electrode feed reel (1) to a state convenient for connection of the electrode. The mechanism has a clutch (3) having an output shaft (5) coupled to the wire electrode feed reel and creating a coupling torque between input and output members (3a, 3b) in a manner changing in accordance with a feed voltage, and a geared motor (M) coupled to an input shaft (6) of the clutch. When the wire electrode is broken, the feed reel is coupled to the geared motor, that is stopped, through the clutch which receives a high voltage and the input and output members of which are firmly engaged with each other, to be prevented from idling. The thus stopped feed reel is then driven by the geared motor at a predetermined torque and a low speed through the clutch which is supplied with a decreased voltage and loosely engaged, to rewind the wire electrode.

Drilling confirming apparatus of electric discharge machining system

Abstract: A drilling confirmation apparatus for an electric discharge machining system automatically, correctly and easily detects the completion of drilling of a hole through a workpiece. A voltage representing a current flowing across a current limiting resistor of the electric discharge machining system is supplied to a divider through a smoothing differential amplifier, representing a detected average machining current. The frequency of a command pulse supplied from a numerical control unit to a servo circuit is converted into a corresponding voltage through a frequency-to-voltage converter. The converted voltage is supplied to the divider as a detected machining speed. The divider divides the detected machining current by the detected machining speed to obtain a machining area signal. The machining area signal and a delayed machining area signal, which is obtained by delaying the machining area signal by a predetermined period of time, are supplied to a comparator. When the delayed machining area signal exceeds the machining area signal, completion of drilling is detected.

Method and apparatus for wire-cut electrical discharge machining

Abstract: A method for wire electrode type electrical discharge machining and equipment employable therefor realize high accuracy in corner machining, such machining being conducted in combination with taper machining. The tension to be applied to a wire electrode is controlled in proportion to a change in Young's modulus of the wire electrode in addition to decreasing the machining current, whenever a corner machining and a taper machining are conducted in combination. The equipment for wire electrode type electrical discharge machining includes a memory for memorizing information indicating the relationship between the machining current and the amount of tension which is optimum to the machining current, a monitor for monitoring the electric discharge machining current, an optimum tension calculating device for calculating the tension optimum to the monitored machining current, and a tension control device for controlling the tension of the wire electrode in response to the calculated optimum tension.

Electric spark machining apparatus

Abstract: An electric spark machining apparatus includes a cooling device which is arranged so that machining liquid pumped up from a reservoir and fed to an electric spark machine is controlled in temperature to minimize a temperature difference between machining liquid entering into the electric spark machine and the latter.

Wire electric discharge machining device

Abstract: PURPOSE:To effectively use a power supply die and reduce a running cost, by forming an external shape of the power supply die in a polygonal shape and changing a contact position of the power supply die with an electrode wire at each rotary movement of the power supply die. CONSTITUTION:The external shape of a power supply die 2a is a polygonal shape, and the internal shape of a holder 3a is also formed in a polygonal shape. In the position of a contact point 16, as an electrode wire 1 passes a point contact condition disappears by gradually wearing the die 2a and the electrode wire 1. Accordingly, a contact condition with the wire 1 is corrected to the initial point contact condition by rotating the die 2a in the direction of an arrow head (a) in the drawing so as to move a vertex B to the position of a vertex A. In this way, the position can be surely changed in accordance with the polygonal shape by further rotating the die 2a to be moved in the direction (a) in each fixed angle, and a contact position of the die 2a with the wire 1 is also surely changed.

Electric discharge machining equipment

Abstract: PURPOSE:To protect an electrode and a workpiece from damage, by stopping the application of voltage pulses between the electrode and the workpiece when the duration or magnitude of a discharge current based on the voltage pulses has been different from a set value for a prescribed time. CONSTITUTION:When a discharge current flows between an electrode 1 and a workpiece 2, an output pulse from a circuit 10 is applied to an element 9 to operate a timer 8. When an element 6 is reset by the timer 8, a timer 7 is operated to repeat discharge. The output pulse from the circuit 10 is also applied to a circuit 12. Output pulses from a generator 13 are counted through the circuit 12. The counted value is compared with a reference number by a comparator 15. If the difference between the compared values is over an allowable range, a pulse is sent to a circuit 24. A shaped pulse signal is applied to a circuit 19 to detect the peak value of the signal. A comparator 21 compares the amplitude of the discharge current with a reference value. If the difference between the compared quantities is over an allowable range, a pulse is sent to the circuit 24. When the number of the pulses from the comparators 15, 21 is larger than a prescribed value, the circuit 24 turns off a transistor 5 and makes a notification.

Electric discharge machining method

Abstract: PURPOSE:To satisfy the roughness of a surface to be processed of a workpiece by setting an average machining voltage on a reverse polarity side so as to decrease the discharge power during positive polarity discharge when an electric discharge process is made by applying positive and negative polarity voltages are applied between the workpiece and an electrode. CONSTITUTION:When a reverse polarity voltage is applied between an electrode P and a workpiece W during a finishing process, just after a positive polarity voltage is applied therebetween, a time constant circuit is energized with the timing of completion of application of the positive polarity voltage, and the output voltage thereof is increased from 0V to a voltage at which the next positive voltage is initiated, with this time constant. During this step, the time point of completion of the application of the reverse polarity voltage is set to a time point at which the level of a voltage VL obtained by adding a predetermined voltage to a voltage which is obtained by dividing a voltage between the electrode P and the workpiece P and then smoothing the thus divided voltage, is attained. Further, since the time at which the reverse polarity voltage varies depending upon the degree of the output voltage VL of the smoothing circuit 1, it is possible to always ensure that the reverse polarity voltage is adjusted to a value which is higher than the positive polarity voltage.

Grinding wheel for electrolytic electric discharge machining

Abstract: PURPOSE:To provide a grinding wheel which can perform simultaneously discharge, electrolysis and mechanical grinding by forming the grinding wheel having grains and foamed metal sintered and an inside electrode and the foamed metal reaching the outer periphery embedded in the grinding wheel. CONSTITUTION:Foamed metal 3 having high porosity and grains 1 included therein are sintered with binder to reach the inside current collecting ring 4 and the outer periphery for forming a grinding wheel. In working, pulse wave form or high frequency voltage are applied between the current collecting ring 4 and a work 6 by the use of a power source 5, and electrolyte 8 is blasted from a nozzle 7 to the grinding wheel body while the grinding wheel is rotated. Discharge and electrolysis take place between the foamed metal 3 and the work 6, while mechanical grinding is also carried out by the grains 1. Thus, any materials difficult to work can be worked with high precision to provide a smooth flat finished surface without any working affected layers.

Machining time estimator for electric discharge machining

Abstract: PURPOSE:To improve the extent of estimating accuracy in machining time, by storing all data necessary to estimate an erosion rate in electric discharge machining from each machining form in advance, and estimating the time required for machining the specified form while referring to the stored contents. CONSTITUTION:Form data such as a projected area and a side area of a machining part, volume, machining depth, electrode size reduced value, surface roughness, etc., are inputted from a work part drawing at a form data input part 1, and machining time is outputted while referring to the stored contents of a data memory part 2 for time estimation, by way of a process at a time estimating processing part 3. This time estimating processing part 3 is provided with a machining form judging part judging a machining form from the form data inputted, an electric condition series selection part selecting an electric condition series to be used for electric discharge machining, a removal amount calculating part calculating a removal amount from electric conditions and form data, a current density calculating part calculating current density at every electric condition and an erosion rate calculating part.

Method for manufacturing a wire electrode for electron discharge machining (spark erosion machining)

Abstract: The method consists in coating a brass wire (2) with a layer of metal or alloy with a low melting point and high vapour tension such as zinc, cadmium, magnesium or alloys of these metals, causing the wire to pass vertically from the bottom to the top through a nozzle (7) supplied with molten metal from a crucible (8). After cooling in an enclosure (10), the wire thus coated is brought to its final diameter and the coating to its useful thickness via a wire drawing operation.

Wire electric discharge machining

Abstract: PURPOSE: To carry out the unmanned work with high precision and in a wide application range by electric-discharge-removing a scrap region with high efficiency, leaving a finished portion, by using a wire electrode having a large diameter and carrying out the work with high precision by an electrode having a small diameter. CONSTITUTION: A workpiece 10 is installed onto a wire electrode feeding device equipped with two pairs of pipe guides 36a and 36b. A scrap region 2 is electric- discharge-removed along a wire electrode path 3 in a desired shape 1 by a device equipped with a wire electrode 38 having a large diameter until a finishing portion on one side (l) is left. Then, the workpiece 10 is transferred onto a device equipped with an electrode 38b having a small diameter, and the rest finished portion (l) is electric-discharge-removed in one or several times, and the finishing to a desired shape 1 is performed. In the above-described operation, the application range to a workpiece having large shape and plate thickness can be spread, and the high working precision can be kept favourably. COPYRIGHT: (C)1988,JPO&Japio