Abstract:
An electrical machining (e.g. EDM) apparatus having a worktank for containing a machining liquid and having a workpiece immersed therein; and a tool electrode positionable to be juxtaposed with the workpiece in the worktank to define an electrical machining gap therebetween filled with the machining liquid. The apparatus includes an ultrasonic assembly disposed in the worktank and comprises a head member and a support member. The head member is constituted by a housing having an ultrasonic transducer element supported therein and an opening for permitting only one of the two opposite surfaces of the transducer element to be held in contact with the machining liquid and to communicate with the region of the machining gap via the machining liquid. The head member is supported in the worktank by the support member, which may include a flexible multi-joint pipe or linkage, so that the opening is directed selectively towards the region of the machining gap. The transducer is energized by a power supply to provide ultrasonic vibrations, preferably in excess of 50 kHz and up to 10 MHz, which are transmitted by the machining liquid preferentially to the machining gap region.
Abstract:
An improved electrochemical grinding wheel electrode consisting essentially of electrically conductive abrasive grains bonded together with an essentially nonconductive bonding matrix. The abrasive grains are admixed with an amount of 10 to 30% by volume of the bonding matrix and sintered together to form the porous, homogeneous electrode body, e.g. in the form of a wheel, having a specific resistivity not greater than 100 ohm-cm, preferably between 0.1 and 10 ohm-cm.
Abstract:
A method of and apparatus for electroerosively forming a 3D contour in a workpiece with a continuous elongate electrode axially transported continuously from a supply unit to a takeup unit to continuously renew a machining surface of the electrode juxtaposed in an electroerosion machining relationship with the workpiece is disclosed in which the continuous elongate electrode traveling between the supply and takeup unit is supported with guide unit carried by a tool head and having an arcuate guide surface juxtaposed with the workpiece to guide the traveling elongate electrode over at least a portion of the arcuate guide surface thereby constituting the machining surface at least in part with at least a portion of the elongate electrode traveling and guided over the guide surface. The tool head is translationally displaced relative to the workpiece so that the aforementioned portion of the elongate electrode moves along a predetermined continuous path in the workpiece while the guide unit carried on the tool head is rotated relative to the workpiece about a rotary axis intersecting the machining surface in a plane defined by the elongate electrode traveling and guided over the guide surface, thereby forming the contour in the workpiece.
Abstract:
A method of and an apparatus for the electrical machining of a conductive workpiece with an axially traveling wire-form electrode displaced transversely to the workpiece along a predetermined cutting path. A high-frequency mechanical vibration is imparted to the wire-form electrode and its amplitude is controlled as a function of the shape of the wire-cutting path.
Abstract:
An EMD method and apparatus, especially for a cavity-sinking type of machining, wherein a combination of magnetic fluxes and ultrasonic waves is applied externally to the region of a machining recess being progressively formed in a workpiece electrode juxtaposed with a tool electrode while the electrodes are displaced relative to one another and a succession of machining electrical pulses are applied across a dielectric flooded machining gap provided therebetween.
Abstract:
An electroerosion machining method and apparatus with a continuous, traveling-wire electrode in which vibrations of frequencies not lower than 100 Hz, preferably at least 1 kHz and of an amplitude of 1 to 50 microns (.mu.m), preferably of at most 5 .mu.m are applied to the traveling wire electrode at opposite sides with respect to the machining region of an electrically conductive workpiece. The method may be used advantageously in reforming a workpiece contour previously shaped by a traveling-wire rough-EDM operation. A resonant circuit connected in series or in parallel with the machining gap and optionally coupled with an external oscillator may be used to energize electromechanical transducers forming vibrator means.
Abstract:
An EDM method and apparatus for supplying successive trains of discrete elementary machining pulses to an EDM gap wherein a high-frequency AC power generally of the frequency of the discrete elementary machining pulses is generated in a high-frequency generating unit disposed remote from the machining gap. The power is transmitted directly in the unrectified AC form along a feeder cable to the proximity of the machining gap whereat a switching rectifier is provided connected to a tool electrode and workpiece across the machining gap via respective conductors of a minimum length. The rectifier operates to cyclically interrupt the transmitted high-frequency AC while concurrently rectifying same, thereby providing successive trains of the discrete elementary machining pulses for direct application across the EDM gap. A discharge state sensor is also disposed in the direct proximity of the gap for sensing the discharge characteristics occurring in the EDM operation a pulser provides a control signal which acts on pulsing for the switching rectifier to modify the cyclic interruption of the transmitted AC and to control production of the successive trains of elementary discharge pulses.
Abstract:
An improved servo system and method in an EDM machine for controlling the relative electrode displacement or the gap spacing between a tool electrode and a workpiece, wherein the electrodes are brought to a machining position to permit a succession of electrical discharges to be developed therebetween across the machining gap. A counter is used to count the number of machining pulses and, when the number reaches a value preset in conjunction with the machining area defined by the confronting electrodes, to provide an "advance" or "advance-enabling" signal. Only upon development of this signal or concurrent development of it and a usual servo "advance" signal from a gap sensor/servo signal generator responsive to a gap variable, e.g. gap voltage, a servo drive circuit acting on a motor or actuator for driving the movable electrode is actuated to allow the electrode to be advanced or stepped forward to a next machining position. The preset level of the discharge counter is varied from one value to another in response to a change in the machining area, setting or gap condition during the course of the machining operation.
Abstract:
In an EDM method, a continuous wire electrode with an original radius is continuously transported through a machining zone of a workpiece. The machining zone is flushed with a liquid while a succession of electrical machining current pulses are passed between the electrode and the workpiece. Because of these machining pulses, discharge craters with raised formations are formed on the wire electrode. The method includes the step of controlling at least one parameter of the electrical machining current pulses so that the radius of the wire electrode at the location of the raised formations does not exceed the original radius of the wire electrode.
Abstract:
EDM method and apparatus in which the electrical-discharge machining pulses are triggered by the application across the machining gap of a succession of pulse trains of discrete pulses whose durations and intervals may be preset for optimum machining conditions (e.g. surface finish). The instantaneous machining area is detected and a time element, such as the duration of each pulse train or the interval between pulse trains or both, is controlled so as to maintain the current density substantially constant in spite of changing machining areas during the machining process.