Showing papers on "Electrical discharge machining published in 1994"
TL;DR: Abrasive-Flow Machining (AFM) is being used to deburr, polish, radius, remove recast layers, or produce compressive residual stresses in a wide range of applications.
131 citations
TL;DR: In this paper, an experimental investigation of EDM of titanium alloy with a copper-tungsten electrode in respect of metal removal rate, electrode wear, surface roughness by varying currents and electrode rotations is presented.
104 citations
TL;DR: In this paper, a combined process with EDM, ECM and electroforming was proposed for the production of precision nozzles with small diameters and various inner shapes, which were successfully produced with good concentricity to the outer profile.
97 citations
85 citations
TL;DR: In this paper, the deviation of the wire position relative to the programmed wire path position is continuously measured and corrections are being made during the machine cutting, which allows to cut complex shapes, arc paths and contours at a much faster cutting speed as compared to conventional wire EDM machines.
79 citations
Journal Article•
48 citations
TL;DR: In this article, a new WEDM adaptive control system that monitors and controls the spark frequency according to the on-line identified workpiece height is presented. But the workpiece length is not considered.
44 citations
35 citations
Patent•
14 Oct 1994TL;DR: A surface treatment method and apparatus therefor for providing wear and corrosion resistance, which includes relatively rotating a modified metallic member to be surface modified and a block, which may be metal only or may include a modifying material (e.g., ceramic or W-C/Co), and generating electrical discharge between the block and the modified metallic part to form a modification layer on the surface of said modified member.
Abstract: A surface treatment method and apparatus therefor for providing wear and corrosion resistance, which includes relatively rotating a modified metallic member to be surface modified and a block, which may be metal only or may include a modifying material (e.g., ceramic or W-C/Co), and generating electrical discharge between the block and the modified metallic member to form a modification layer on the surface of said modified metallic member. If the modifying material is not in the block, it can be supplied via a dielectric bath or spray at the discharge interface. In this manner, the cutting edges of a cutting tool with a complicated shape can be surface modified easily to carry out tool surface treatment which increases a cutting tool life greatly. Cutting and surface treatment can be performed alternately as determined by a controller.
35 citations
TL;DR: In this article, the machining characteristics of 3D form and cylindrical tools were investigated and the most beneficial results when selecting one of these machining methods were shown. And the economical comparison between these machined methods based upon EDM machining and hand finishing times.
Abstract: The need for better utilization of Electro Discharge Machining (EDM) machines with a minimum cost has forced researchers and machine tool builders to carry out a great deal of development to provide optimum conditions for the EDM process. In this respect, the application of Computer Numeric Control (CNC) to EDM has added a new dimension to the ways in which the electrode and workpiece can be moved relative to each other. It has also increased the efficiency and productivity of the process. However, the CNC system, introduced on ram-type EDM machines, offers more than just the capability for positioning the electrodes and process control. It also facilitates more sophisticated tool motions and the ability to generate complex shapes with simply shaped electrodes. This paper investigates the machining characteristics of 3D form and cylindrical tools and shows the most beneficial results when selecting one of these machining methods. Finally, the paper introduces the economical comparison between these machining methods based upon EDM machining and hand finishing times.
34 citations
TL;DR: In this paper, a new method for improving the EDM (electrical discharge machining) performance of a Ti-6Al-4V alloy is investigated, and the experimental results indicate that the best overall performance is achieved using ultrasonic vibration dielectric.
Abstract: A new method for improving the EDM (electrical discharge machining) performance of a Ti-6Al-4V alloy is investigated. The experimental results indicate that the best overall performance is achieved using ultrasonic vibration dielectric. The improvement mechanism is that the ultrasonic vibration results in the restraining of discharge concentration and the formation of small debris. It is also found to be effective for promoting the machined surface roughness to use ultrasonic vibration dielectric suspended with electrically conductive powder such as pure aluminum powder.
TL;DR: In this paper, the feasibility of electrical-discharge machining (EDM) conducted on the Al 2 O 3 -Cr 3 C 2 composites was explored for various contents and particle sizes of Cr 3C 2 in composites.
TL;DR: The EDM process offers a rapid, accurate, and simple technique to correct for casting inaccuracies in the fabrication of hybrid implant prostheses.
Abstract: Purpose
An absolutely passive fit at the interface with the superstructure and the abutment cylinders is needed for implant longevity. In this study, a method of cast framework correction using electric discharge machining (EDM) was evaluated.
Materials and Methods
An original research model incorporating strain gages was devised to measure the fit of implant superstructures in three dimensions as cast and to compare this relationship with the fit following framework machining with EDM.
Results
Visually, the fit of the frameworks was excellent, and the results of ANOVA demonstrated that the mean fit of the frameworks significantly improved (P > .04) after machining with EDM.
Conclusions
The EDM process offers a rapid, accurate, and simple technique to correct for casting inaccuracies in the fabrication of hybrid implant prostheses.
Patent•
28 Sep 1994TL;DR: In this paper, a method of preparing metal surfaces for thermally applied coatings by electrical discharge is described, which controllably provides greater roughness for increased mechanical coating adhesion, avoids carbon deposits and more economical to use.
Abstract: A method of preparing metal surfaces for thermally applied coatings by electrical discharge, which method controllably provides greater roughness for increased mechanical coating adhesion, avoids carbon deposits and is more economical to use. The method comprises melting and rapidly solidifying globules of the metal surface by spark erosion, the spark erosion occurring by incidence of an electrical discharge between an electrode and the metal surface closely spaced thereto, the spacing having an electrolyte with plasma forming capabilities, the discharge resulting from application of an electrical current to the electrode with a DC voltage in the range of 60-85 volts and amperage in the range of 50-110 amps, the current being pulsed on for periods of 150-300 micro seconds per spark.
01 Jan 1994
TL;DR: In this article, a method of measuring the energy distributed into the electrodes in EDM processes is described, and the energy is determined by means of comparing the computed electrode temperature with the measured one.
Abstract: In this paper, a method of measuring the energy distributed into the electrodes in EDM processes is described. The energy is determined by means of comparing the computed electrode temperature with the measured one. It is found that the energy distributed into the anode and cathode is nearly the same, and is 15 to 30 percent of the total discharge energy into each. The influences of some factors on the energy distribution are also studied. Key words: Electrical Discharge Machining; Energy Distribution; Electrode Temperature; Single Pulse
Patent•
28 Jan 1994TL;DR: An apparatus and method for fast hole drilling by electrical discharge machining is described in this article, which includes an indexable table (12) and a rigid vertical frame (14) which straddles the table and a slide member (16) cooperatively attached to the frame.
Abstract: An apparatus and method for fast hole drilling by electrical discharge machining The apparatus includes an indexable table (12) and a rigid vertical frame (14) which straddles the table (12) A slide member (16) is cooperatively attached to the frame (14) so that it may move in relation thereto A plurality of advancable and retractable heads (18, 20, 22) are associated with the slide member (16) and are adaptable for electrical discharge machining Each head (18, 20, 22) is adjustably inclinable in a plane which lies parallel to the slide member (16) Each head (18, 20, 22) includes a rotatable, hollow electrode (24) defining an axially extending channel (28) A dielectric fluid (50) passes along the channel (28) so that machining debris may be transported away from a workpiece (11) and drilling operation may proceed in a force-free, non-contacting manner
Patent•
02 Feb 1994TL;DR: In this article, the retraction speed commands are also directly input into corresponding speed loop control sections to produce correction movement amounts which are then added to the axial movement amounts and input into the corresponding position loop control section.
Abstract: An electric discharge machining apparatus generates an electric discharge by applying a voltage across a tool electrode and a workpiece Axial movement amounts for controlling the tool electrode are first input into a plurality of corresponding position loop control sections and speed loop control sections to thereby control corresponding servomechanisms An electric discharge machining condition corresponding to a gap between the tool and the workpiece is then detected by a gap condition detector To maintain an appropriate electric discharge machining condition, a detected value and a target value of the tool are subtracted to produce a deviation value The deviation value is then multiplied by axial components of a direction vector to produce retraction speed commands Integrators integrate the retraction speed commands to produce correction movement amounts which are then added to the axial movement amounts and input into corresponding position loop control sections The retraction speed commands are also directly input into corresponding speed loop control sections to thereby effect movement of the tool electrode
Patent•
21 Dec 1994
TL;DR: In this article, a method of determining electric discharge machining machining conditions comprises the steps of establishing multiple sets of predefined machining parameters, establishing for each set of basic machining data indicating relationships present during electric discharge Machining among electric discharge current, machining depth and minimum electrode side surface undersize.
Abstract: A method of determining electric discharge machining conditions comprises the steps of establishing multiple sets of predefined machining parameters, establishing for each set of predefined machining parameters a set of basic machining data indicating relationships present during electric discharge machining among electric discharge machining current, machining depth and minimum electrode side surface undersize, selecting at least two sets of basic machining data from among the multiple sets thereof in accordance with a given set of predefined machining parameters, and inferring and thereupon generating machining condition data representing a series of pairs of values comprising machining depth values and corresponding electric discharge machining current values for machining the workpiece to a prescribed configuration and prescribed dimensions, the electric discharge machining current values in the series progressively changes with increasing machining depth value from a value larger than the electric discharge machining current of the selected set of basic machining data to a value smaller than the electric discharge machining current of the selected set of basic machining data.
Patent•
28 Mar 1994TL;DR: In this paper, a method and apparatus for micro-electric discharge machining that machines electrically resistant materials having high volume resistivity, such as Mn-Zn ferrite or single crystal silicon material, with a ciruit including an electrode connected to a positive terminal of a power supply and the workpiece of electricallyresistant material is connected to the negative terminal of the power supply is described.
Abstract: A method and apparatus for micro-electric discharge machining that machines electrically resistant materials having high volume resistivity, such as Mn--Zn ferrite or single crystal silicon material, with a ciruit including an electrode connected to a positive terminal of a power supply and the workpiece of electrically resistant material is connected to a negative terminal of a power supply. The circuit can include a capacitor having a capacitance less than 5000 pF.
Patent•
18 Jan 1994
TL;DR: In this article, an isolator and an automatic adjusting means for the matching circuit are provided to minimize the feedback of reflected power to the power supply in order to prevent the internal damage of a power supply, thus improving machining efficiency and stability.
Abstract: PURPOSE:To generate electric discharge of short time width at high repetition frequency and make the removal unit of workpieces minute so as to obtain high removal efficiency. CONSTITUTION:High frequency A.C. power is applied to an electric discharge gap between a machining tool electrode 6 and a workpiece 7 by a high frequency A. C. power supply 1 to perform electric discharge machining. The impedance matching of the electric discharge gap and a feeder circuit is performed by a matching circuit. The impedance matching of the matching circuit is adjusted according to finish machining or rough machining, and a discharge current is limited to reduce discharge energy so as to perform fine machining for finish machining. Or discharge energy is increased to perform rough machining. An isolator and an automatic adjusting means for the matching circuit are provided to minimize the feedback of reflected power to the power supply in order to prevent the internal damage of the power supply, thus improving machining efficiency and stability. The intermittent duty ratio of the power supply 1 is adjusted by a feed adjusting device 2 to control electric discharge density.
TL;DR: In this article, a calibration system with polyhedra is installed on the machine to measure the shape of an electrode and a workpiece during the process of electrical discharge machining.
Patent•
13 Jan 1994
TL;DR: In this paper, a monitoring device for electric discharge machining is presented, which is capable of monitoring the variation state of the monitoring values which indicate the machining conditions of an electrical discharge machine.
Abstract: PURPOSE: To provide a monitoring device capable of monitoring the variation state of the monitoring values which indicate the machining conditions of an electrical discharge machine CONSTITUTION: The monitoring device for electric discharge machine comprises a memory means 32 to store electric discharge indicating the advancing conditions of electric discharge machining for each sampling time of machining process, an indicating means 50 to indicate the advancing conditions of electric discharge machining based on the monitoring values for the sampling time read from the W means 32, and a converting means 30 to convert the monitoring values for indication on the indicating means 50 COPYRIGHT: (C)1995,JPO
Patent•
16 Jun 1994
TL;DR: In this paper, the EDM apparatus for machining a workpiece by electric discharge while supplying dielectric fluid which contains powder to the work gap formed by a tool electrode and the workpiece to be machined includes a cover to protect them against the adherence of the powder that is contained in the powder, a fluid feeding device supplying the powder-containing fluid during the electric discharge machine process, and, at the same time, also supplying fluid that does not contain any powder to parts inside the cover.
Abstract: The EDM apparatus for machining a workpiece by electric discharge while supplying dielectric fluid which contains powder to the work gap formed by a tool electrode and the workpiece to be machined includes a cover to protect them against the adherence of the powder that is contained in the dielectric fluid, a fluid feeding device supplying the powder-containing fluid to the work gap during the electric discharge machine process, and, at the same time, also supplying fluid that does not contain any powder to the parts inside the cover.
Patent•
15 Mar 1994TL;DR: In this article, a stick-like electrode was inserted during electric discharge machining to form a first deep opening, retracting the electrode, repeatedly shifting the location of the electrode and inserting the electrode while electric discharge mashing to connect adjacent deep openings.
Abstract: A method of forming a shape such as a groove by inserting a stick-like electrode during electric discharge machining to form a first deep opening, retracting the electrode, repeatedly shifting the location of the electrode and inserting the electrode while electric discharge machining to connect adjacent deep openings.
Patent•
21 Oct 1994
TL;DR: In this article, a neural network is used to learn the relationship between the specifications and machining conditions using the selected basic data, and an inference portion determines an optimum machining condition based on the data set in relation to the specifications.
Abstract: In a machining condition setting device for electrical discharge machining for setting machining conditions including pulse energy and an electrode feeding distance based on data set in relation to specifications including the quality of a material of a workpiece and the desired surface roughness of a product, a plurality of sets of basic data are selected which show relationships between machining conditions and specifications provided by the machining conditions. An inference portion including a neural network is caused to learn the relationship between the specifications and machining conditions using the selected basic data. The inference portion determines an optimum machining condition based on the data set in relation to the specifications. Consequently, a storing portion needs store only basic data relatively low in amount.
Patent•
20 Jul 1994TL;DR: In this article, a traveling wire electric discharge machining apparatus machines a workpiece by applying periodic voltage pulses to a wire electrode while moving the wire electrode relative to the workpiece, according to a predetermined parameter.
Abstract: A traveling wire electric discharge machining apparatus machines a workpiece by applying periodic voltage pulses to a wire electrode while moving the wire electrode relative to the workpiece. A location on the workpiece is determined, according to a predetermined parameter. The location is before a change in machining direction of the workpiece. When the wire electrode is positioned at the determined location, a characteristic of the periodic voltage pulse is changed.
TL;DR: In this article, the bottom profile of EDM machined with a rectangular electrode has complex undulation along the groove, since the smooth flow of dielectric fluid is obstructed.
Abstract: Electrical discharge machining of a deep groove is generally difficult by the conventional method, since the removal of debris generated during the machining becomes more difficult with an increase of the groove depth.EDM of groove with a rotating disk electrode is proposed in this paper and the performance of this method is experimentally investigated, comparing with that of conventional method. Main conclusions obtained in this study are as follows;(1) The bottom profile of groove machined with a rectangular electrode has complex undulation along the groove, since the smooth flow of dielectric fluid is obstructed.(2) Stable EDM of groove is attainable with a rotating disk electrode, since the smooth flow of machining fluid leads to effective removal of debri.(3) The machining time of EDM with a rotating disk electrode is shorter than that of EDM with a rectangular electrode for larger number of revolution.(4) The groove of setting depth can be generated by controlling the depth of cut according to the analysis of electrode wear in EDM with a rotating disk electrode.
Patent•
05 Aug 1994TL;DR: In this article, a laser guided discharge machining (LDDH) was used to enable parts of the workpiece to be discharge machined which are not in a direct line from the discharge electrode.
Abstract: A laser guided discharge machining apparatus includes a vacuum chamber in which pressure can be reduced to 3000 Pa or below and in which a workpiece is accommodated as well as a discharge electrode that emits charged particles. A laser beam is used to guide the discharge to thereby enable parts of the workpiece to be discharge machined which are not in a direct line from the discharge electrode.
Patent•
02 Feb 1994
TL;DR: In this paper, a new type of combined pole jig relates to the field of spark erosion technique; the pole can freely adjust the length during working, overcoming some defects which comprise the manufacture of the pole, troublesomely using, and the precision and the quality of the machining hole are asymmetry.
Abstract: A new type of combined pole jig relates to the field of spark erosion technique Though altering the structure of the jig, the utility model makes that the pole can freely adjust the length during working, overcoming some defects which comprise the manufacture of the pole, troublesomely using, and that the precision and the quality of the machining hole are asymmetry, and the utility model has the advantages of easy use, shortcut assembly and disassembly of the pole thread, the uniform length, flat surface, and that the precision of the machining hole is enhanced to +-003 millimeter