Abstract: A method of producing a multi-apertured workpiece such as a fuel injector comprising forming an aperture in a workpiece by EDM machining (10), supplying a calibrating fluid such as deionised water through the aperture from a reservoir (17) via a pump (18), measuring the flow and pressure through the aperture by transducers (19, 20) and comparing the results with a predetermined ideal, adjusting the EDM machine (10) in accordance with such comparison so as to compensate for the difference between the measured values and the predetermined ideal, forming a further aperture using the adjusted EDM machine (10) and repeating the preceding steps until the appropriate number of apertures has been formed. The apparatus may include CNC operation (14) and the comparison may be made by computer (15) linked to the CNC (14) for adjusting the EDM machine (10).

Abstract: A method of producing a multi-apertured workpiece such as a fuel injector comprising forming an aperture in a workpiece by EDM machining (10), supplying a calibrating fluid such as deionized water through the aperture from a reservoir (17) via a pump (18), measuring the flow and pressure through the aperture by transducers (19, 20) and comparing the results with a predetermined ideal, adjusting the EDM machine (10) in accordance with such comparison so as to compensate for the difference between the measured values and the predetermined ideal, forming a further aperture using the adjusted EDM machine (10) and repeating the preceding steps until the appropriate number of apertures has been formed. The apparatus may include CNC operation (14) and the comparison may be made by computer (15) linked to the CNC (14) for adjusting the EDM machine (10).

Abstract: A method of machining a workpiece at a plurality of working positions, employing a pulsed laser under external control, comprises effecting continuous relative movement of the workpiece and the laser the rate of movement being synchronized with the laser firing so that on successive laser pulses the laser beam is aligned with different work positions on the workpiece. Apparatus for machining a workpiece according to this method comprises a mechanism for effecting continuous relative movement of the workpiece and a pulsed laser operable under external control, a position transducer to determine the relative positioning of the workpiece and the laser, and a closed feedback control loop to ensure that each time the laser is pulsed it is aligned with a predetermined work position on the workpiece, the rate of movement being similar to the rated pulse repetition rate where possible.

Abstract: A method of shaping a nose portion 5 of an electrode 4 in an EDM apparatus comprises, providing a grinding element 9 having a peripheral groove 10 and means for effecting relative movement between the electrode 4 and the grinding element 9, and feeding the electrode 4 into the groove 10 tangentially or normally thereto so that the nose portion 5 contacts and is ground by one of the two opposed side faces of the groove 10 to impart a complementary profile to a first side face 20 of the nose portion 5.

Abstract: An element, such as an electrode, to be clamped by a clamping device passes slidingly through the interior of a rigid tube, a portion of which is disposed in a fluid chamber defined within a body of the clamping device. A flexible tube, for example made of nitrile rubber, surrounds said portion of the rigid tube and the latter has a part thereof cut away to expose the electrode to the flexible tube. Fluid in the chamber can be pressurized to a relatively high level in order to press the flexible tube against the electrode and thereby clamp the latter firmly, or to a relatively low level in order to retain the electrode frictionally while allowing it to move through the rigid tube.

Abstract: A method of machining a workpiece to a predetermined depth using an electrode machining discharge apparatus including electrodes which wear during the machining process. The machining of a workpiece to a first level is effected, after which the electrodes are withdrawn and a refeed member having a surface matching that of the workpiece is positioned for engagement with the electrodes, followed by the electrodes engaging the refeed member to align the ends thereof, after which the machining operation continues. The machining operations are in increments less than the depth to which the machining is to be effective, and several alignments of the electrodes may be required.

Abstract: This disclosure relates to the refeeding of one or more electrodes of an electrical discharge machining apparatus after the electrodes have been used and unevenly worn. The electrodes are mounted within a cartridge which includes an element which offers frictional resistance to the movement of the electrodes relative to the cartridge so that when the cartridge is advanced to engage the electrodes with a workpiece the electrodes are automatically recessed within the cartridge until the tips of all electrodes are aligned. A clamp is provided for then securely clamping the electrodes against further movement relative to the cartridge.

Abstract: This invention discloses a cartridge for containing electrodes which are fed to the nose guide of an electrical discharge machining apparatus. The cartridge has a carriage which contains the electrodes and moves with respect to the nose guide. An electrode clamp is provided to lock the electrodes in position in the cartridge together with means offering frictional resistance to sliding movement of the electrodes upon release of the clamp.