Showing papers on "Electrical discharge machining published in 1983"

Ceramics containing fibers of silicon carbide

Abstract: Ceramics incorporating fibrous crystals of silicon carbide, optionally, in combination with an electroconductive substance have high electroconductivity and are amenable to electric discharge machining.

Wire-cut electric discharge machine

Abstract: A wire-cut electric discharge machine having an improved nozzle system for supplying working fluid into a working gap between a workpiece and wire electrode. The improved nozzle system comprises a working fluid nozzle coaxial with the wire electrode and an auxiliary nozzle for producing an intense jet stream in the back portion of the wire electrode, namely, into the slit formed by the spark erosion. The jet stream pressure acts on the semicylindrical surface opposite the front surface at which the discharge pressure is produced to preserve the linearity of the wire electrode.

Method and apparatus for cutting off a portion of a workpiece by electrical discharge machining, and for supporting the portion cut off from the workpiece

Abstract: A support mechanism for a workpiece cut off by electrical discharges in a travelling wire EDM apparatus. The workpiece is supported between support members provided with clamps. One support member is controllably pivotable around a horizontal axis, while the second support member is displaceable vertically and horizontally along crossed axes. In addition, the second support member may be rotated around a vertical axis. Through appropriate sequential operation of the clamps and relative displacement of the support members, the areas of the workpiece clamped by the clamps may be changed at will, and the cuttings from the workpiece may be supported by one of the clamp members to prevent the fall of the cuttings at the end of a cutting operation.

Nozzle and power-feed element for wire-cut electrical discharge machine

Abstract: A wire-cut electrical discharge machine which effects an electrical discharges between a wire electrode and the workpiece. The wire-cut machine has a supply nozzle for supplying a machining fluid to an electrical discharge machining zone and a power-feed element for supplying pulse power to the wire electrode. The power-feed element contacting the wire electrode is provided inside the supply nozzle.

Wire-cut electric discharge machining method

Abstract: A wire-cut electric discharge machining system is provided with a high-current, short-pulse discharge circuit for producing a high-current, short-pulse discharge between a wire and a workpiece, a low-current, pulse discharge circuit for producing a low-current, pulse discharge between the wire and the workpiece, and a control unit to alternately use both discharge circuits and to control the relative movement of the wire with respect to the workpiece. Main cutting along a predetermined path by the high-current, short-pulse discharge circuit is followed by at least one second cutting along a path adjacent the main cutting path by the low-current, pulse discharge circuit for each predetermined section, thereby performing electric discharge machining of the workpiece at an overall reduction of time.

Using the weight of the electrode or workpiece to control EDM working conditions

Abstract: An electrical discharge machine is provided with at least one weight measuring apparatus for detecting the weight of one or both of an electrode and a workpiece, and a control unit for selecting or controlling the working conditions in response to the output of the weight measuring apparatus. The weights of the electrode and the workpiece are measured after the working operation has been interrupted temporarily, or while continuing the working operation. Well-known various accurate balances or force measuring apparatuses may be used as the weight measuring apparatus. A microcomputer including a numerical control unit may be used as the control unit.

Wire electrode for wire-cut electric spark machining

Abstract: PURPOSE: To obtain a wire electrode for wire-cut electric spark machining with high electric conductivity, high tensile strength and superior stress corrosion resistance by adding specified amounts of Fe, P, Zn and Pb to a Cu matrix. CONSTITUTION: This wire electrode for wire-cut electric spark machining consists of, by weight, 2W3% Fe, 0.01W0.04% P, 0.05W0.3% Zn, ≤0.03% Pb and the balance Cu with inevitable impurities. The surface of the wire electrode may be coated with Zn, Mg, Sn, Pb, Al, Cd or an alloy thereof. The wire electrode enables rapid and accurate machining while extremely reducing the amount of a deposit. When the wire electrode is stored, it is required only to wind rust preventing paper around the electrode, and vacuum packing is made unnecessary. COPYRIGHT: (C)1985,JPO&Japio

Method and apparatus for machining a workpiece in a travelling wire EDM apparatus

Abstract: A travelling wire EDM apparatus wherein a workpiece is cut by electrical discharges by a travelling wire electrode, relative motion of the workpiece and the wire electrode being controlled by a numerical control unit which, in addition, controls transverse oscillations of the electrode wire relative to the workpiece along the cutting path. The energy of the electrical discharges is varied as a function of the amplitude of the transverse oscillations of the electrode wire relative to the workpiece such as to obtain maximum electrical discharge energy when the amplitude of vibration of the electrode wire is at a minimum and minimum energy when the amplitude of vibration of the electrode wire is at a maximum. The invention permits to achieve a good surface finish on the machined surface of the workpiece corresponding to the peak of the transverse electrode wire oscillation displacement being reached simultaneously with minimum electrical discharge energy, and thus achieves rough cutting and finish cutting of the workpiece in a single pass.

Control of wire-cut electric discharge machining unit

Abstract: PURPOSE:To redcue the working error on corner working within the permissible value by correcting the electric discharge power on corner working, the tension of a wire electrode, and the feeding speed, on the basis of the deflection amount of the wire electrode when straight working is preformed. CONSTITUTION:When a corner part is worked through the wire-cut electric discharge machining, working errors 3a and 3b are generated according to the deflection amount of a wire electrode 1. The work instruction data read from a tape reader 26 is stored in a memory 28, and treated in a calculation unit 25, and the brake roller controlling circuit 9 of the wire electrode, work-feeding motor controlling circuit 22, and a power source condenser switching circuit 7 are controlled through an interface 29. The working power, the tension of the wire electrode, and the feeding speed are calculated and corrected according to each deflection amount D1, D2 in case of straight working so that the corner error delta can be reduced within the permissible value.

Method and device for the adaptive control of an electrical discharge machining process

Abstract: The method and the device for the adaptive control of an electrical discharge machining process prevent undesirable effects of abnormal discharges in the working gap between the tool and the workpiece, and the working conditions can be improved by automatic control of the tool. According to the method, the discharges in the working gap are identified by means of the device, the frequency of the effective discharges occurring is continuously compared with the frequency of the abnormal discharges and, on the basis of these results, which are compared with preset values, the supply of the electrical discharge machining pulses to the tool is interrupted for a certain time, the working gap is changed and the machine for the electrical discharge machining process is switched off if the ratio of the frequency of the abnormal discharges to the frequency of the effective discharges becomes too large.

Electric discharge machine with control of the machining pulse's current value in accordance with the delay time

Abstract: In an electric discharge machine having a main switching circuit 24 for supplying a current high in current peak value between which are an electrode 10 and a workpiece 12, and an auxiliary switching circuit 26 for supplying a current low in current peak value between the electrodes, to intermittently cause electric discharge between the electrodes which are the electrode 10 and the workpiece; a voltage is applied across the electrodes by the auxiliary switching circuit 26, and when no electric discharge occurs between the electrodes before a decision set time of 1 to 4 μsec, the application of the voltage across the electrodes by the auxiliary switching circuit 26 is continued until discharge occurs therebetween and when the discharge occurs the main switching circuit 24 is caused to supply a normal current between the electrodes according to a given surface roughness, and when discharge or short-circuiting occurs between the electrodes before the decision set time the main switching circuit 24 or the auxiliary switching circuit 26 is caused to supply a current smaller than the normal current between the electrode. As a result the machining speed for the surface roughness of the workpiece is increased, and the machining stability is improved.

Wire cut electrical discharge machining apparatus with electric feeders in a tubular guide

Abstract: In a wire cut electrical discharge machining apparatus having an automatic wire feeder which feeds an electrode wire 10 through the material 12 to be machined automatically, electricity feeders 70 for supplying electrical energy for the machining operation to the wire 10 are disposed within a tubular guide 64 through which the wire 10 extends. The tubular guide 64 is improved in rigidity, and improved reliability is achieved in the supply of electricity to the wire.

Apparatus for supplying a working fluid and a wire electrode to a work portion of a wire-cut electrical discharge machine

Abstract: Apparatus for supplying a working fluid and a wire electrode to a wire region of a wire-cut electrical discharge machine comprising a housing supported by a support member and having opposed aligned openings through which a wire electrode is passed into operation association with a workpiece at the work region to be operated on by the electrode. A working fluid is supplied under pressure into the housing and the working fluid passes through a nozzle supported in the housing against the workpiece. The nozzle is positioned in the housing to surround the wire electrode which travels therethrough and it projects from the housing to discharge the working fluid against the workpiece at a gap formed therewith. A guide die is supported in the housing to guide the wire electrode through the housing and the nozzle. Electrical energy is supplied to the wire electrode before it enters the housing and a second nozzle is supported by the housing to discharge working fluid against the electrical supply system to cool the same.

Electrodes correct device for electric discharge machining

Abstract: PURPOSE:To provide an arrangement in which the worn parts of a tool electrode are removed automatically, by furnishing an electrode to correct the configuration of the tool electrode, in the processing vessel and by a making its positional relation changeable. CONSTITUTION:A work 3 in the processing vessel 1 is subjected to electrospark machining with a tool electrode 4. This tool electrode 4 is shifted to a position mating with a modifying electrode 10 when the end part of the tool electrode 4 have worn, and the electric discharge machining is executed upon setting the tool electrode 4 in the optimum condition. The correcting electrode 10 is rotated by a motor to reciprocate in the X and Y directions. According to this arrangement to correct a tool electrode, both coarse and finish processing can be done with a single electrode, that assures a processing with high precision.

Generic electrode EDM method and apparatus, and assembly for maintaining chip concentration in the gap at an enhanced level

Abstract: An EDM method and apparatus, utilizing a generic electrode, i.e. a tool electrode independent in shape of a desired cavity or contour to be machined in a workpiece, and utilizing a three-dimensional machining feed displacement, makes use of an assembly for maintaining the contamination of the machining liquid with machining products, e.g. chips and gases, at a certain enhanced level. The assembly includes a pad or block member disposed in the proximity of the workpiece with a small spacing therewith while surrounding the generic electrode to mechanically control or limit discharging of the machining products out of the EDM gap, thereby enabling a stabilized production of machining electrical discharges across the EDM gap maintained substantially constant.

Electric discharge machining unit

Abstract: PURPOSE:To make it possible to do machining with high precision from one side of a work by providing an electric discharge machining unit with an electrode corrector to make a distorted electrode straight, a roller to give a certain tension to the electrode, a processing liquid nozzle, and an electrode cutter. CONSTITUTION:On an electrode unit mounting plate 1b of a self-propelled carriage 1 are provided a tape feed drum 2, a guide roller 3, a damping roller 4, a tension roller 5 concurrently serving as a feed roller, an electrode corrector 6 with a straight-correct roller 7, an electrode cutter 8, and a machining head 9. On a main body 1a are provided a processing liquid supply tank 10 and a pump 11, which move along with the self-propelled carriage 1. A tape electrode 12 is fed from the tape feed drum 2, and passes through the damping roller 4 via the guide roller 3. Then it is sent to the electrode corrector 6 to be made straight, and then transmitted to the machining head 9 through the tension roller 5 concurrently serving as the feed roller and the electrode cutter 8. Thus it is finally sent out to the machining section from one side of the work 13.

Electric discharge machining condition setting system

Abstract: A wire cut electric discharge machining condition setting system including cursor shift push button switches for selecting with a cursor one of the machining conditions displayed on a screen at a CRT display unit, numerical push button switches for setting values of the selected machining conditions, and increment and decrement push button switches for continuously updating the preset values of the machining conditions all arranged in a wire cut electric discharge machine The value of the machining condition selected with the cursor is set by the numerical push button switches and is updated by the increment and decrement push button switches

Automatic wire feeder for an electrical discharge machining apparatus including combined cleaning fluid and working fluid supply systems

Abstract: A device for feeding an electrode wire 2 automatically from a wire supply reel 1 to a work hole 77 in the material 38 to be machined, and therefrom to a recovery system for the electrode wire includes a cleaning device for injecting a fluid against a guide member 40 for the electrode wire to blow away dust or any other contaminant matter to ensure that the electrode can be successfully supplied for a long period of time.

Alignment tooling for metal cylinder welding machines

Abstract: An alignment tool is provided for use in a metal cylindrical can welding machine which is an integral unit constructed of discrete component parts comprising an insulating part and a guide part of high strength and hardness. The insulating part prevents electrical current from passing through the alignment tool thereby preventing spark erosion, increased wear and inefficiency. The high strength part provides the necessary characteristics required for guiding the edges of the can body blanks to the welding rollers and can be selectively replaced for repair or modification thereby reducing repair costs.

Electric discharge machining

Abstract: PURPOSE:To enable to bore the desired hole with high accuracy without taking the consumption of electrode into consideration by a method wherein the consumption rate of the electrode is obtained and the electric discharge machining is carried out with the instructed shift amount corrected based upon the obtained consumption rate. CONSTITUTION:When the thickness LO of the work piece W is inputted as the shift amount of the electrode to a numerically controlling unit NC, the unit NC sends an instruction pulse to a servo unit SVZ before starting the electrical discharge machining so as to store the detection result Z1 of a position detector PC in a memory based upon the output of a comparator COM, which is issued when the tip of the electrode P contacts with the work piece W. After that, the unit NC separates the electrode P from the work piece W and then applies a control signal to a power source SE so as to start discharging and then to instruct the units SV and SVZ in order to shift the electrode P by the shift amount LO and then to stop and at the same time the electrode P is stopped, to pull up the electrode P out of the machined hole. After that, the detection result Z2 obtained by contacting the tip of the electrode P moved away from the machined hole with the work piece W is stored. The consumption amount DELTAl and the consumption rate alpha of the electrode is calculated based upon the detection results Z1 and Z2 in order to obtain the amount to shift L1 to shift further thereupon.

Role of Dielectric Flushing on Electric Discharge Machining Performance

Abstract: Importance and influence of dielectric fluid flushing are discussed and some representative experimental results are presented. It is found that, by changing dielectric fluid pressure, it is possible to obtain 20–30 % change in erosion rates of both workpiece and tool electrodes. Method of flushing does not affect machining performance. Circulation of dielectric fluid by tool electrode vibration is also studied. A dependence of erosion rate on vibration amplitude is observed. Maximum erosion rate is obtained at 5–10 µm peak to peak amplitudes for all machining conditions. A simple mathematical model for the influence of dielectric pressure on machining rate is presented.

Wire EDM for detecting discharge concentrations using inductance

Abstract: A wire type electric discharge machining device monitors the location of discharges occurring within the gap between a wire electrode and workpiece. The location is determined as a function of the inductance between the discharge point and the power supply, which inductance is determined by examining the discharge current waveform. When an excessive number of consecutive discharges occur at the same location in the gap, the device regulates the value of the pulse voltage applied to the machining gap, or the quiescent time thereof.

Guide system of wire cut electric discharge machining wire electrode

Abstract: PURPOSE:To improve straightness and machining accuracy of a wire electrode, by arranging die-type guides in positions holding a work further a pair of diagonal V-groove type guides to the outsides of the former said guides. CONSTITUTION:At wire cut electric discharge machining, die-type guides 2 are arranged in positions interposing a work 5 approximately to the work 5. Further a pair of diagonal V-groove type guides are arranged to the outsides of said guides 2 to constitute a guide system of a wire electrode 6. By such guide system, straightness of the wire electrode can be correctly held to improve machining accuracy of the wire cut electric discharge machining.

Electrical discharge machining method for wire cut

Abstract: PURPOSE:To prevent a separated workpiece from dropping by leaving only the one part of the workpiece in its height direction while inclining a wire electrode in the wire travelling direction just before completion of the electrical discharge machining for wire cut. CONSTITUTION:Electrical discharge is generated between a workpiece 1 and a wire electrode 5 supported with wire guides 7, 8 and the workpiece 1 is sent, allowing it to be cut and machined into a closed loop shape. When a residual part 6 not yet machined changes into a prescribed width just before the completion of machining, only the lower side wire guide 8 is sent in the machining direction while keeping the upper side wire guide 7 to stop, and only the one part of a residual part 6' to be machined is left in its height direction with the completion of machining. Thereafter, the workpiece is separated by striking it with a hammer or by cutting it with a fretsaw.