Showing papers on "Electrical discharge machining published in 1982"

Process and device for treatment of metal-bonded nonconductive materials

Abstract: A rotating electrode tool made of polycrystalline synthetic diamonds in a metal foundation is used in the electro-erosive machining and mechanical grinding of a metal bonded, electrically non-conductive hard material such as synthetic diamonds or boron nitrides in an electrically conductive metal matrix. The tool is first used to electro-erosively machine the workpiece. When a signal is obtained from the machining current or voltage indicating that no further electroerosive removal is possible, the tool automatically mechanically grinds the workpiece to remove nonconductive particles not removed by spark erosion.

Electrode wire for electric discharge machining

Abstract: PURPOSE: To improve the workability and electric discharge machining characteristics, by adding prescribed percentages of Zn, Be and Cu or by further adding a rare earth element. CONSTITUTION: The titled electrode wire consists of 20W50wt% Zn, 0.2W1wt% Be and the balance Cu or further contains 0.5W1wt% rare earth element. The electric discharge characteristics are improved, the strength at high temp. is easily maintained, and the working is facilitated. When the electrode wire is used, the surface state and dimensional accuracy of the resulting machined product are improved. COPYRIGHT: (C)1984,JPO&Japio

Wire cut electric discharge machining power source

Abstract: A wire-cut, electric-discharge machining power source which is provided with a first low-current discharge circuit and a second high-current discharge circuit. The first low-current discharge circuit makes a wire electrode positive and a workpiece negative, and the second high-current discharge circuit makes the wire electrode negative and the work positive. After triggering a discharge by the first low-current discharge circuit, a main discharge for machining is produced by the second high-current discharge circuit.

Wire-cut electric discharge machining method using stored machining instructions

Abstract: A method of electric discharge machining using a wire electrode for cutting a workpiece into a commanded shape by producing an electric discharge between the workpiece and the wire electrode and moving the wire electrode relative to the workpiece along a commanded path. The method includes steps of previously storing, in a computer memory, sets of machining conditions which differ depending upon workpiece material and thickness, reading, at the time the workpiece is to be machined, a predetermined set of the machining conditions from the memory in response to a machining condition selection instruction in a machining program and performing electric discharge machining in accordance with the set of machining conditions read from the memory.

Fully automated machining apparatus optimization for electric discharge machining apparatus

Abstract: An electric discharge machining apparatus capable of automatically optimizing the machining stabilizing condition including set voltage of machining pulse, duty factor of the pulse, electrode raising period and working fluid pressure, and hence capable of being full-automated. Each machining stabilizing condition is successively changed within a predetermined range and set when the maximum effective discharge generation rate is obtained. Spark machining is effected on the basis of the set value.

Breakthrough detection means for electric discharge machining apparatus

Abstract: An EDM machining apparatus is provided with means for automatic shut off upon completion of a machining process, including a voltage variation pattern detector capable of discriminating electrode penetration of the workpiece. Several other machining parameters, such as machining solution flow and pressure, machining depth, and electrode speed and direction may be used is secondary or confirmation detection factors, so as to positively detect the time of electrode penetration, and halt the machining process.

Method of and apparatus for machining a 3-D cavity in a workpiece

Abstract: A method of forming a cavity of a desired three-dimensional contour in a workpiece utilizes two steps of machining operation. In the first step (a), a multiplicity of holes are mechanically drilled in the workpiece substantially all over but within a three-dimensional region which is destined to constitute the cavity and which is bounded by a programmed outline corresponding to the desired three-dimensional contour whereby only a minimum of stock is left unmachined in the workpiece within the region. In the second step of operation (b), the minimum left unmachined stock among the holes and within the region is electroerosively machined with at least one electrical machining tool electrode having a machining surface which is complementary with the desired contour and which is positioned to lie in parallel with the programmed outline, by, (b1) passing an electrical machining current across a machining gap between the machining surface and the region in the presence of an electrical machining liquid in the multiple holes and the gap, and (b2) advancing the tool electrode relatively into the workpiece while maintaining the aforesaid parallelism and holding the machining gap spacing substantially constant until the machining surface reaches a position spaced by the said spacing from the said programmed outline.

Wire cut electric discharge machining method

Abstract: PURPOSE:To prevent generation of a residual machined part or deformation of a work when cutting work is performed in the method of wire cut electric dischage machining, by arranging its machining liquid and condition for adhering material susceptible of being accumulated to the work and closing a machined groove then holding a falling part. CONSTITUTION:A work 12 is electric discharge machined by a wire cut electrode 10, then adhering material 24 is acumulated to an end of the work 12 at the side the wire electrode 10 is fed. To increase an accumulated amount of this adhering material, electrolytic action by applied voltage is reduced. That is, such machining conditions are required as increase of specific resistance of machining liquid, decrease of mean machining voltage, increase of capacity of a capacitor in an electric discharge circuit, high frequency of applied voltage, etc. If the accumulated amount of the adhering material 24 is increased to close a machined groove 16, a falling part of the work is held by the adhering material 24, then deformation of the work or generation of a residual machined part can be prevented at completion of machining work.

Apparatus for orienting the wire electrode support and guide member and the machining fluid nozzle of a travelling wire EDM apparatus

Abstract: In a travelling wire EDM apparatus, a unitary assembly of at least one of the electrode wire support members and a machining fluid nozzle disposed coaxially to the wire is installed on a plate which is displaceable such as to provide the electrode wire passing through the machining zone in the workpiece with an appropriate inclination. Inclination of the unitary assembly of the electrode wire support member and machining fluid nozzle is obtained by a swivel member mounted on the plate and oriented by a tube through which the electrode wire is passed. The tube is supported along its length by a pivot which is at all times disposed symmetrically to the electrode wire lower support member relative to a plane of symmetry. The unitary assembly is also supported by a swivel joint member interconnected to the first swivel joint member such that the angular displacement of the respective swivel joint members are symmetrical.

Method of and apparatus for electroerosively wire-cutting a conductive workpiece

Abstract: A wire-cut electroerosion machining method and apparatus in which the rate of axial travel of the electrode wire is temporarily increased immediately upon a change by the electrode wire of its course at a corner in a prescribed cutting path. The axial travel rate is preferably increased as a function of the angle of intersection defining the corner. Also, the time period in which the wire axial travel rate is increased should advantageously be varied as a function of, e.g. in inverse proportion to, the angle of intersection defining the corner.

Methods and apparatus for the electrical machining of a workpiece

Abstract: In combining electrical discharge machining (EDM) and electrochemical machining (ECM) the use of a strong electrolyte has, in the invention, been found possible. In one embodiment a pulse generator applies an intermittent voltage between an electrode and a workpiece causing both EDM and ECM to take place when a strong electrolyte is interposed in the gap between the electrode and the workpiece. At the onset of arcing a discharge monitor removes the voltage. A wire-cutting machine and method combining EDM and ECM are also described.

Investigation on the Use of Water As a Dielectric Liquid in E.D.M.

Abstract: This paper summarizes the experimental investigations conducted on the Electric Discharge Machining (E.D.M.) where water has been used as dielectric liquid instead of usual hydrocarbon oils. Distilled water, tap water and water with salt and glycerine additives have been used in the presented research. The best machining performances have been obtained when distilled water is used. The experimental results for distilled water are compared with the results obtained for commercial kerosene, which is the most common dielectric liquid for E.D.M. applications.

Automatic supply method of wire in wire cut electric discharge machining device

Abstract: PURPOSE:To improve reliability in the automatic supply method of a wire, by detecting supply failure due to a trouble to again repeat and successfully perform automatic supply of the wire during its automatic supply to an electric discharge machining device. CONSTITUTION:To detect supply failure of a wire electrode 2, detection for a change of advancing speed of the wire 2 is only required, and the change is detected by replacing the speed to the intermittent motion of a direction changing pulley 5. An encoder 91 is mounted to the pulley 5 to output AC voltage in a range 0-5V, and a DC component is cut by a capacitor C1 and a resistor R1. Then R3/R2 times amplification is performed by an OP amplifier 92. At the time of a waveform W3, a relay coil L1 is in an OFF condition, and the occurrence of intermittent motion of the pulley 5 can be detected. Further from an OFF condition of a relay coil L2, the electrode 2 located out of its insertion route can be detected. Then a newly fed wire electrode is again automatically supplied.

Power supply unit for electric discharge machine

Abstract: The present invention relates to a power supply unit for an electric discharge device of the type used in electric discharge machining. First and second DC sources are employed, and the output of the two sources are applied to the machining gap, by way of main and auxiliary switching circuits. The output of the first DC source is applied to the machining gap initially, and a discrimination device operates to detect whether normal electric discharge takes place. The second DC source is applied to the machining gap in dependence upon the operation of the main switching circuit, the operation of which is in turn dependent upon the output of the discrimination circuit and a delay pulse derived from an oscillator which initiates the closure of said auxiliary switching circuit.

Electrode wire for wire-cut electric discharge machining

Abstract: PURPOSE:To achieve a wire electrode having excellent machining speed and low adhesion by employing alloy composed of Cu, Zn, Al and Si as the wire electrode material. CONSTITUTION:An alloy containing Zn: 26-38wt%, Al: 0.2-1.5wt%, Si: 0.2- 1.0wt% and impurities inevitable with Cu is employed as the wire electrode material for wire-cut electric discharge machining. When adding one or more than two kinds of Mn, Sn, Mg, Zr by 0.2-1.0wt%, the machining speed and adhesion to the workpiece can be improved.

Characteristics of the surfaces obtained in electro-discharge machining

Abstract: According to the established thermal theories on electro-discharge machining (edm), the size of the craters produced in edm is proportional to the discharge energy, which is equal to the product of mean pulse current and pulse duration for a constant gap voltage. As a practical edm surface is a random superposition of such craters, the behaviour of the surfaces largely depends on the two important parameters, pulse current and pulse duration. With the help of multiple linear regression analysis, the effect of pulse duration and pulse current on the surface topography parameters R q and β∗ has been studied. sem photomicrographs have been taken in support of the qualitative evidence

Electrolytic/electric discharge machining of a non-conductive workpiece

Abstract: The electrolytic/electric discharge machining of a workpiece of a non-conductive hard material, for example, ceramic material is carried out by preparing a grinding wheel having conductive regions and non-conductive abrasive regions circumferentially alternately arranged on the circumferential edge of the wheel, and bringing the rotating grinding wheel in contact with the workpiece while applying AC or DC voltage across the grinding wheel and the non-conductive workpiece.

EDM using two separate dielectric fluids and a system for maintaining segregation of the fluids

Abstract: In an electric discharge machining method, a workpiece is subjected to an electric discharge machining at a high working speed using water as the dielectric fluid, and after this, the workpiece is finish-machined using oil as the dielectric fluid. An apparatus for carrying out the method has a feeding system for selectively feeding water or oil as the quenched surface of a workpiece is removed by using water as a dielectric fluid in electric discharge machining (EDM) the dielectric fluid to a machining gap between the workpiece and a tool electrode and a returning device for selectively returning the dielectric fluid used in the machining gap to an oil tank or a water tank.

Wire electrical discharge machine flushing process and apparatus

Abstract: OF THE DISCLOSURE Method and apparatus are set forth for forming a substantially enclosed longitudinal path along the cutting surface of a workpiece and substantially enclosing a cutting wire of electrical discharge machining equipment so as to confine and direct dielectric fluid supplied thereto along such cutting wire to flush out eroded particles formed during the cutting of a slot in the surface of the workpiece. Furthermore, a method of improving the cutting rate and depth of cut of multiple slots produced within a workpiece is disclosed which includes the formation of initial counter slots in the surface of the workpiece having a width sub-stantially larger than the width of the desired functional slots to be formed in said workpiece. The invention is of particular interest in the formation of long thin slots of accurate configuration such as in ceramic honeycomb structures which require accurately parallel sidewalls which must be burr-free and have consistent surface finish. In particular, it achieves good repeatability by providing consistently identical channels or slots in work pieces.

Fluid delivery rate control tw electrical machining method and apparatus

Abstract: A method of and an apparatus for electrical-machining a conductive workpiece with an axially traveling wire electrode displaced transversely to the workpiece along a predetermined cutting path to advance electroerosion effected across the machining gap supplied with a machining liquid, wherein the rate of supply of the machining liquid to the gap is controlled as a function of the shape of the cutting path.

Method for manufacturing tire molding metal molds with a two-stage electrical discharge machining process

Abstract: A method of making a mold which is utilized to manufacture a tire, the mold having a contour curved surface with broad bone portions and narrow blade portions extending therefrom, comprises a first machining stage utilizing a plurality of electrical discharge machining electrodes for approaching a workpiece used to make the mold, at different angles. Each of the electrodes used in the first machining stage are shaped to avoid the removal of excessive metal from the mold so that both the bone portions and the blade portions can extend normally from the contour curved surface. The method includes a second machining stage utilizing a further electrical discharge machining electrode which has recesses for receiving bone portions and blade portions formed by the first stage electrodes, and is movable laterally of the contour surface to form well-defined edges of the bone and blade portions.

EDM Of a roll using segmented electrode short-circuited in the rough machine step

Abstract: There is disclosed a method for electrical discharge machining of a workpiece in the form of a roll by application of an electrical voltage across said workpiece and an electrode or electrodes mounted opposite to each other with a predetermined gap therebetween, and more particularly such method wherein each such electrode is formed by plural electrode segments separated from one another by insulators, and the electrical discharge operation is performed with said electrode segments in each electrode short-circuited to one another in the rough machining step and with said electrode segments insulated from one another in the finish machining step for reducing the working time.

Method of and apparatus for electrical discharge machining using a gas-dissolved water liquid

Abstract: A novel EDM method is disclosed in which a gas such as compressed air is dissolved in a water liquid to form a solution which is pumped into the machining gap formed between a tool electrode and a workpiece. An EDM power supply provides a succession of electrical discharges across the gap through the supplied solution to electroerosively remove stock from the workpiece with the decomposition of oxygen and hydrogen gases from the water liquid. The dissolved gas in the solution is liberated in the machining gap upon exposure to the electrical discharges to add to these gases, thereby increasing the electroerosive stock removal. The gas is dissolved into the water in an amount of at least 20% by volume of the oxygen and hydrogen gases normally decomposed from the water liquid by the electrical discharges. An apparatus for executing the method includes a pressure chamber traversed by the pumped flow of the water liquid and having a gas supply inlet through which the compressed gas is introduced for solubilization in the water liquid. The region of the machining gap is preferably enclosed in a second pressure chamber maintained under a superatmospheric pressure to limit the spontaneous liberation of the dissolved gas from the water liquid.

Electrical discharge machining device

Abstract: PURPOSE:To improve electrical discharge machining speed by making machining liquid convective effectively by means of an NC device having a position detecting sensor of a machining electrode and a jumping device and by changing convection of machining liquid independently of machining depth. CONSTITUTION:An electrode position detecting sensor 9 is provided on a head 6 and an electrode 7 is jumped through an electrode jumping device 14 by the signal of said sensor. Detecting signal value from the sensor 9 is stored in an NC device 10 and compared with electrode transfer amount at each predetermined time by a comparison circuit 15, and change of UP/DOWN amount of the device 14 is instructed based on the compared value. Convection of machining liquid is changed by changing jumping amount to improve machining speed.

Composite wire for wire-cut electric discharge machining electrode wire and manufacturing method thereof

Abstract: PURPOSE:To improve the electroic discharge machining performance of a wire electrode, by installing an intermediate layer of an alloy, containing at least one type of Ni, Fe and Co, on an outer circumference of a copper or copper alloyed core material, while designing so as to install an outmost layer of a zinc alloy on the outer circumference. CONSTITUTION:The outer circumference of a copper or copper alloyed core material 1 is clad by 1-2mu in thickness with an intermediate layer consisting of metals of at least one type of Ni, Fe and Co or an alloy containing it, by means of plating, etc. In addition, its outside is covered with an outmost layer composed of zinc or a zinc alloy. Owing to this intermediate layer, a brittle compound layer vulnerable to the diffusion of copper and zinc is in no case formed there, so that not only electric discharge machining performance is well improved but also the productivity at the time of manufacturing the wire electrode becomes higher than ever before.

Automatic wire-guide device

Abstract: The automatic wire-guide device in a wire-electrode discharge machine in which a wire electrode is passed from a top die to a bottom die during the electrical discharge machining of a workpiece arranged between the top die and the bottom die, in the course of which a spark is transferred in a narrow gap between the wire electrode and the workpiece, comprises a guide head for the insertion of the wire electrode, in which guide head a cutting device, a guide-tube arrangement and feed rollers for the wire electrodes are arranged. The guide head can be moved from an inoperative position into a first operating position between the top die and the bottom die, the cutting device being put into the path of the wire electrode so that the wire electrode can be cut off and the used, cut-off part of the wire electrode can be taken out of the machine, which enables the workpiece to be removed from the machine and a new workpiece to be inserted for the following electrical discharge machining operation. Furthermore, the insertion head can be moved into a second operating position after the wire electrode has been cut off and the new workpiece inserted, the guide-tube arrangement being aligned with the path of the wire electrode between the top die and the bottom die and being movable along the path of the wire electrode to the bottom die, which enables the wire electrode to be guided by the guide-tube arrangement from the top die through the new workpiece into the bottom die. The guide-tube arrangement is provided with a longitudinal slot which extends along the entire length so that the guide head can be returned from the second operating position into the inoperative position, while the wire electrode is held between the top die and the bottom die. This takes place owing to the fact that the wire electrode runs through the slot of the guide-tube arrangement, and the latter can be removed out of the path of the wire electrode so that the following electrical discharge machining of the new workpiece can be carried out.

A method for wire-cut electric discharge machining

Abstract: The invention relates to cutting a work (W) into a closed loop configuration by means of a wire-cut, electric discharge machine provided with an automatic wire feed mechanism. Electric discharge machining is started from a machining start hole (31) made in the work (W) and is performed to a point (C) of suspension of the electric discharge machining operation where a part (32) of the closed loop configuration is left uncut. After fixing at least one portion of the closed loop configuration (33) to the work (W) by adhesive (34) and reinserting the wire electrode into the machining start hole (31) by the automatic wire feed mechanism, the electric discharge machining operation is resumed to cut off the part (B-C) remaining uncut. In the case of the wire electrode being broken during the electric discharge machining operation, the wire electrode is reinserted by the automatic wire feed mechanism into the machining start hole (31) and is moved to the position of its breakage along the route where the machining operation has already been performed and then the electric discharge machining operation is resumed.

Control system of electrode jump in electric discharge machine

Abstract: PURPOSE:To enable a short-circuit between an electrode and a work due to the cutting of electric discharge machining to be prevented by allowing the electrode to jump. CONSTITUTION:When a work is moved by a motor 105 in accordance with NC data of a tape 101 and machined by an electrified electrode EP, if a short-circuit between the electrode and the work is caused by the cutting of a machine, a short-circuit signal SS is input to an input/output board 102f, and a processor 102a interrupts execution of a machining control program but executes the program of a program memory 102b through a bus 102i. In this way, a backward pulse BS in the reverse direction is generated from a pulse distributor 103, and the content of an error register 107b becomes zero after a prescribed time, causing the electrode EP to move backward and jump by the backward pulse. If the short-circuit is released, the signal SS disappears while the processor 102a detects disappearance of this signal, causing the electrode EP to advance and restart its machining feed.