Abstract: A tool system features an EDM crack removal head which can be positioned within a nozzle/thermal sleeve and then oscillated in a vertical and horizontal directions to enable precise material removal, leaving the surface free of cracks and in a condition for rewelding if required. If a crack is found in a surface which is covered by a thermal sleeve, then a small specialized EDM cutting head, which can be delivered from the under side of the reactor head and has an ability to pass through the ID of the thermal sleeve, is used. The head enables the sleeve to be cut and allow a portion of the sleeve to be removed. The crack can then be removed using a crack removal type of head.

Abstract: A method and device for removal of a specimen (30), especially a parallelepipedal specimen, from within the internal wall of the vessel of a nuclear reactor which is at the end of its service and whose core has previously been dismantled, but which retains a high residual radioactivity. A rotating platform (10) carrying tools (23, 24) for cutting out by electrical discharge is inserted into the vessel (1), maintained under protective water (7). A first electrode produces a recess in a direction perpendicular to the internal wall (21) of the vessel, delimiting the external contour of the specimen, and a second electrode cuts the rear of the latter to a specified depth, before the withdrawal thereof from the wall. The specimen thus obtained is then extracted from the vessel.

Abstract: An electric discharge machine has a movable ram assembly including a casing having a tubular support defining a through bore therein with an upper portion, a lower portion and a receiving space adjacent to the lower portion. A shaft vertically passes through the bore and the lower end of the shaft is connected to an electrode head. A device for moving the shaft vertically in the tubular support is provided in the casing. The casing also has an upper telescopic member extending upward from the upper portion and a lower telescopic member extending from the lower portion thereof. An insulating device is provided between the shaft and the tubular support to insulate the casing from the shaft. The insulating device includes an insulated tubular member in the lower portion, an insulated sleeve member around the shaft between the upper and lower portions, an insulated stop member at the top end of the shaft.

Abstract: An electron discharge machining tool (10) for removal of conductive material from a workpiece such as a plug (28) in a nuclear steam generator tube (26) is an end effector connected to a remotely operated manipulator arm by a mount (56). A piston (47) drives a hollow conductive rod (44) with a graphite electrode cutter (30) in reciprocating motion through receptacle (14) having a restrictive drain (37) and containing deionized water. The reciprocation of rod (44) is controlled by power supply (50) sensing the electrical potential and signalling valve (48) which controls hydraulic flow in conduits (54a, 54b) communicated to opposite sides of the piston (47). A TV camera (32) and a light (34) mounted behind a lens (36) are used to monitor the machining.

Abstract: A process for manufacturing impellers of turbine pumps provides for subjecting disks corresponding to the impeller to be obtained to electrical discharge machining, using tools in form of plates provided with radial slits extending along at least an arc of circumference and opening into hollow areas. A combined motion of rotation and translation is imparted to the disks, thus generating twisted blades having a profile with defined geometric characteristics. A one-piece rotor can be manufactured employing open tools with slits formed along a semicircumference, and two passages in succession of the workpiece through the tools, moving the workpiece with a combined motion of rotation and translation. An advantageous application of the articles manufactured by this process is for rotors of turbomolecular pumps, since the compression ratio and the pumping speed are optimized and a considerable structural sturdiness of the article is obtained.

Abstract: Structure for and method of electrical discharge machining with a wire electrode to produce small holes including completely controlling electrical discharge machining parameters such as voltage, reactance, current and servo speed with a programmable microprocessor, central processing unit sensing first sparking between the wire electrode and the workpiece and controlling depth of cut from the position of the electrode on spark initiation electrode feeding to replenish eroded electrode through clamping sequencing between an electrical discharge machine head and an electrode carrying slide thereon. In accordance with the invention there is also provided ultrasonic vibration of at least one of the workpiece, a wire electrode guide and the electrode during machining.

Abstract: An apparatus for electrical processing according to the present invention comprises a machine tool, a power supply means and a working fluid system. A tool is rotatably mounted on the machine tool. A workpiece and the tool are connected to the output terminals of the power supply means. In course of the processing, the tool is rotated through a motor, and working fluid is applied to the tool and the workpiece by the working fluid system. The operation voltage and current rnage from 25V to 28V and 1600A to 3000A respectively for a rough processing, and 1V to 9V and 1A to 90A for a fine processing.

Abstract: A device for machining a cylindrically shaped gas turbine engine component includes a computer numerical controlled lathe and a wheel-shaped electrode for spark erosion machining of the component. The lathe includes a faceplate for mounting and rotating the component, and a gage surface is concentrically mounted relative to the component on the faceplate for in-process determination of a largest gaged radius of the wheel-shaped electrode. The radius is determined by the computer numerical control when an electronic current sensing circuit signals the computer numerical control that the electrode has contacted the gage surface. The electrode can then be positioned relative to the component, to correct for erosion of material from the electrode caused by the previous machining cycle, before a subsequent machining cycle.

Abstract: The body (4) of the plug (3) is rebored in the direction of its end wall (6) and the clamp block (7) is drilled by an electric machining process, over a substantial part of the length of the plug. The wall of the plug body (4) is relieved of stress with the aid of a welding torch introduced into the bore made by electric machining, and a gripping tool is introduced into the bore in order to extract from the tube the plug body (4) which has been relieved of stress.

Abstract: The machine has a rotary device for holding and rotating a workpiece to be processed, an electrode disposed to oppose the workpiece, an indexing device for holding the electrode and indexing the electrode at a predetermined angular pitch, a power supply device for applying a voltage between the workpiece and the electrode so as to cause the electric discharge therebetween, and a cutting device for cutting a portion of the electrode which has been used for the electric discharge and has been indexed by the indexing device to face the cutting device. The consumed portions of the electrode are successively indexed to the position where the cutting device is set so that the consumed portion of the electrode is successively cut without requiring the processing to be stopped.

Abstract: A machining tool is provided with an electric discharge truing/dressing apparatus comprising a spindle stock for containing and supporting a workpiece spindle which is driven for rotation while holding a workpiece or an electrode; a tool rest which moves parallel and perpendicular to the spindle of the spindle stock and holds an electrode machining tool and a grinding wheel; a feed electricity means disposed between a workpiece supporting portion of the spindle and the tool rest; a magazine disposed at an outside area of a machining area of the tool rest and adapted to store the workpiece and the electrode; and a loading device disposed between the magazine and the spindle. The grinding wheel on the tool rest is subjected to truing/dressing by feeding the electrode from the magazine to the spindle stock.

Abstract: An automatic wire feeding apparatus for an electrodischarge machine has a pipe guide for guiding a wire electrode from a feed roller to wire guides, for insertion through a starting hole in a workpiece. Compressed air fed into the pipe guide forces the wire electrode to vibrate during insertion. A contact detecting circuit detects contact between the wire electrode and the pipe guide. If the contact state continues for a certain time, indicating that insertion is impeded, a control circuit initiates corrective action by stopping the feed roller, cutting the wire electrode, then resuming feeding or by temporarily reversing the feed roller, then resuming forward feeding. Initiation of the corrective action is timed to occur before the wire electrode might ride off the feed roller.

Abstract: A spark erosion machine tool is equipped with a drive head carrying, at an angle to its moving direction, a plurality of drive slides, with a stationary work piece holder, and with a plurality of movable spark erosion electrode mounting bucks. The drive slides (4) cooperate with the mounting bucks (20) for converting the movement of the drive head into a movement of the spark erosion electrodes. For example, when the drive head is a ring, its axial movement relative to a round work piece, such as a combustion chamber of a jet engine, is converted into radial movements of the erosion electrodes for plunge cutting cooling slots or openings into the outer jacket of the combustion chamber. Thus, many slots can be cut simultaneously. The movable mounting bucks (20) carry electrode holders (16) and the bucks are movably supported on guide rods (25) in the stationary work piece holder. The electrodes with their holders are guided in slots (14) of the work piece holder.

Abstract: A machine tool produces a tapered slot by moving a tool laterally of the workpiece as well as directly into it. The lateral movement is shortened at the end of each half reciprocation, so as to form the taper. The shortened stroke is achieved by use of electronic circuitry in which transducers are utilized to indicate by voltage output, the magnitude of movement of the tool into the workpiece relative to the magnitude of the movement of the tool laterally thereof and on positive or negative numerical pair being noted, deriving a further signal therefrom and utilizing it to change the direction of reciprocation.

Abstract: An apparatus for electroerosive piercing of holes in workpieces having an electrode tool in the form of a rod placed with a clearance in a shell and projecting therefrom, a device for feeding and rotating the rod mechanically connected to a device for reciprocating the shell relative to the rod. The device for reciprocating the shell relative to the rod is fashioned as a hydraulic cylinder, a piston of which has the shell rigidly secured thereto at the side of the workpiece, and at least one cavity of the hydrauylic cylinder is connected to a system for feeding and discharging a working fluid, the piston having at least one passage communicable with the interior of the shell of the electrode tool and wherethrough the rod of the electrode tool extends with a clearance.

Abstract: A machining tool with an electric discharge truing and dressing apparatus comprising a spindle stock for containing and supporting a workpiece spindle which is driven for rotation while holding a workpiece or an electrode. A tool rest moves parallel and perpendicular to the spindle of the spindle stock and holds an electrode machining tool and a grinding wheel. An electricity feed element is disposed between a workpiece supportng portion of the spindle and the tool rest. A magazine is disposed at an outside area of a machining area of the tool rest and is adapted to store the workpiece and the electrode. A loading device is disposed between the magazine and the spindle. The grinding wheel on the tool rest is subjected to truing and dressing by feeding the electrode from the magazine to the spindle stock.

Abstract: To drill small holes in a metal component having a non-conductive, e.g. ceramic, surface layer apparatus is provided capable of carrying out both ultrasonic and EDM drilling operations without dismounting the component. The drilling operation commences with an ultrasonic drilling phase and change over to essentially EDM operation when breakthrough of the ceramic surface layer is detected. Breakthrough is detected by applying a low voltage pulse signal to a drilling electrode and sensing when current starts to flow between the electrode and the workpiece. When a multiplicity of holes are drilled simultaneously the changeover to EDM is triggered by breakthrough of the first electrode but may be delayed to permit the remaining electrodes to breakthrough.

Abstract: A process for the mechanical sharpening of workpieces using electrically conductive sharpening tools provides that, procedurally, first an electric spark gap is created between a sharpening tool (18) and workpiece during the contact of the sharpening tool (18) on the workpiece (10), and the contact position is determined by the arc discharge. Subsequently, for the sharpening process, the spark gap or potential is disconnected or is adjusted to such a value that essentially only a mechanical material removal occurs. The process is especially advantageous as executed on a device which provides electro-erosion processing or sharpening by the effects of electro-erosion, because then the control circuit (32) which is present for these purposes can be used not only for control of the spark gap during the electro-erosion treatment, but also for the contact of the sharpening tool.

Abstract: A portable electrode arc cutting tool 11 for cutting internal and external precision notches in a work surface in which the tool is releasably attachable to the work surface and a calibrated feed control (14,112,185) is used to bring a surface configured electrode member (68,101,173) into close proximity to the work surface. Thereafter, upon the application of arc discharges of electrical current between the electrode member and the work surface and use of a cooling and flushing fluid, the electrode member cuts a precision depth notch in the work surface in an embodiment for internal use within pipe. The tool includes releasable attachment means (12,91,141) for stabilizing the tool within the bore of the pipe. In a tool used for external cutting of notches, the tool is releasably attached to an outer work surface.

Abstract: A process method for planetary erosion of an existing depression using a finishing or dressing operation. A non-circular target path is used instead of the prior art method of a circular target path and predominantly circular translational movements so that the geometric shape of the electrode does not result in the workpiece volume being eroded much slower at the non-corner surface regions than in the corner regions. A preset target value path is defined for each planetary revolution by determining the actual movement of at least one preceeding planetary revolution based on the difference between the target value path and the actual value path, with each preset target value path being delimited by the final target value path.

Abstract: The process serves to control the step-by-step feed motion or touch-on motion of a grinding wheel (18) relative to a workpiece (10) or a measuring sensor. In so doing, a sequence of measured values of the power consumption of the rotary drive motor (24) of the grinding wheel (18) is recorded. If a specific sequence of measured current values remains under a certain limiting value, a further touch-on step is triggered. With the touch-on control system the touch-on motion is terminated, when the measured current values attain a specific limiting value. This touch-on control system forms the second phase of a combined touch-on control process in whose first phase a sparking current is generated and measured between the grinding tool (18) and the workpiece (10), which serves as a measurement of the distance between these.

Abstract: The invention relates to duplicating intaglio print elements in steel by using an engraved copper art model as a template for a copper electrode which in turn is utilized in an electro-erosion machining process to produce the steel workpieces. The invention is particularly applicable to making intaglio print elements for printing on bank note paper and more particularly for printing paper money.

Abstract: The device comprises a support (11) equipped with a fastening element, an assembly (12) mounted movably relative to the support (11) in the direction of the axis (8) of the tubular piece, a pole (13) mounted in the assembly (12) in the direction of the axis (8), an electrode holder (14) in several parts, and an actuating rod mounted movably in the pole (13) in the direction of the axis (8), in order to ensure the spacing of the various parts of the electrode-holder (14) and the radial movement of the electrodes. A vibrator (16) enables vibration of the pole (13) and the electrode-holder (14) in the direction of the axis (8). In a first phase, the wall of the tubular piece is pierced as a result of the radial movement of the electrodes, and in a second phase, cutting is carried out as a result of the axial movement of the movable assembly (12) carrying the pole (13).

Abstract: An electrode return control system for an electric spark machine includes a first control mode in which, when a short-circuit condition occurs, an electrode is moved away from its position in a workpiece along a path over which the electrode was advanced for machining, and a second mode in which an object point to which the electrode is to be moved directly upon the occurrence of a short-circuit condition is updated with the machining progress.

Abstract: A device for machining by electroerosion has a tool electrode driven in a rotary motion controlled by a servomotor and showing the shape of a solid of revolution around its axis of rotation. A measuring circuit continuously evaluates the degree of contamination of the machining dielectric liquid in relation to a reference value. The measurement is made by a transducer for the instantaneous voltage U.sub.i of each spark and by comparing it to a predetermined value U.sub.b, thus determining the proportion of so-called low-level sparks for which U.sub.i .ltoreq.U.sub.b, a signal being delivered when this proportion surpasses a predetermined threshold, or by a current transductor working during the waiting time preceding the striking of each spark, a signal being delivered when a predetermined current threshold is attained. A servo circuit modulates the rotation speed of the tool electrode as a function of this signal. The detector makes it possible to detect and remedy the appearance of ejected sparks.

Abstract: A rotary sheet die suitable for use in the cutting of paper webs and the like is manufactured by securing the sheet to a hollow mandrel using mechanical clamps and internal vaccum. The mandrel and sheet assembly is then placed in an EDM apparatus in which vertical movement of the electrode is gear synchronized with the rotary movement of the mandrel and sheet combination. Chilled dielectric fluid is used to flush and cool the electrode and sheet die interface.

Abstract: A device for electrical discharge piercing of holes in components comprises a tool electrode mounted in an electrode holder (18) and made as a rod (26) enclosed, with a clearance, in a sheath (27) and somewhat projecting therefrom, and a contrivance for traversing, locking and wear compensation of the tool electrode.

Abstract: A method an apparatus for machining a workpiece by use of a conductive grindstone, and for dressing the grindstone simultaneously with the machining process.

Abstract: A method and apparatus control relative movement between an electrode of an DM machine and a workpiece. The method provides for positioning each point of a path of relative movement between the electrode and the workpiece by the distance of the point from an axis of rotation, rotating the workpiece, positioning the point also by an angle through which the workpiece is rotated, memorizing the position of each point of the path, and repeating the steps of positioning the points. The apparatus includes a rotatable work table driven by a servo motor and encoder to rotate the table to a desired angle. A device for polarizing the workpiece is provided to avoid interference with the rotation of the table on which the workpiece is mounted. The apparatus further includes machinery for translating the work table or the electrode along an axis that intersects the axis of rotation for the table.

Abstract: An apparatus for machining metal substrates such as honeycomb seals is provided. The apparatus includes a spindle unit including a motor and shaft. The motor is used for rotating the spindle shaft about its longitudinal axis. The spindle shaft is connected to a power source which converts it and a tool head secured thereto to an electrode. The electrode is positioned in close proximity to a rotating workpiece such that an arc is formed between it and the workpiece. Power to the electrode is adjustable to control the rate of metal removal from the workpiece. Circuitry is used to cut off power to the spindle shaft when the current from the power source exceeds a certain amperage for an extended period of time (such as three seconds to prevent nuisance cut off). The circuitry also allows arcing between the electrode and the workpiece without cutting off power to the spindle shaft.