| 摘要 |
EDM apparatus for electric discharge machining a hollow three-dimensional contour while compensating for the wear on the rotary working electrodes whose diameter is small compared to the dimensions of the hollow contour to be machined. The EDM machine is adjusted for machining at a constant volume wear rate, preferably at a high wear regime, and has computerised means for storing the volume of the hollow contour to be machined in the form of a superposition of thin parallel virtual layers and simulating a trajectory of the electrodes such that its tip successively sweeps each of these layers furrow by furrow. A simulator makes an a priori calculation of the longitudinal wear of the rotary working electrode, or of a parameter intended to cause additional axial advance of the working electrode, such as to continuously compensate for its longitudinal wear, for example the tangent of the angle alpha which the oblique direction of advance of the tool in the workpiece is to make with the plane of the layer to be hollowed, so that the active end of the working electrode remains parallel to the plane of this layer. This calculation is carried out from pre-existing technological parameters and characteristics of the geometry of the electrodes, such as the volume wear rate and/or the thickness of the layer of material which it is desired to machine and/or the radius of the working electrode and/or the thickness of its wall. This simulator transmits a corresponding signal, continuously compensating for this wear, to the numerical control unit of the EDM machine controlling the 3D movement of the working electrode. The working electrode is either a cylinder or a hollow tube. <IMAGE>
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