Ateliers Des Charmilles S.a.

Charmilles Technologies S.a.

Alain Wavre

Jean Pfau

Rudolf Schneider

Michel P Mazond

Georges Semon

In a travelling wire EDM apparatus for effecting a cut by electrical discharges on a workpiece blank by an electrode wire, the workpiece blank is supported by two support members mounted on a rotary table, one support member being disposed in the interior of the perimeter of the cutting path and the other support member being disposed exteriorly to the perimeter of the cutting path such as to support the two portions of the workpiece blank severed from each other during the cutting operation. A partial cut is first effected through the workpiece blank and the workpiece blank is subsequently angularly oriented to a different position by rotating the rotary table such that collision between any one of the electrode wire support arms and the workpiece blank support member disposed within the perimeter of the cutting path is prevented. The cut is continued along a cutting path corrected as a function of the new angular position of the workpiece, and at the end of the cut the portion severed from the workpiece blank is supported by the support member disposed within the perimeter of the cutting path and the remaining of the workpiece blank is supported by the other support member.

EDM apparatus provided with means for holding a portion cut off from the

A method and apparatus for compensating for the wear of an electrode tool during machining by EDM of an electrode workpiece by the electrode tool. During penetration of the electrode tool into the electrode workpiece, relative displacement of the electrodes is stopped as soon as it reaches a predetermined reference position corresponding for example to a machining depth limit data entered in a control buffer memory. The reference position data is corrected as a function of the actual wear of the electrode tool which is measured by comparing the positions taken by the electrode tool when one of its active surfaces reaches the same reference position before and after a machining pass. The correction of the reference position data may be obtained either by successive approximations, or by a single calculation step effected after the first machining pass.

Method and apparatus for electrode tool wear compensation

The present invention is a process and apparatus for machining an electrode workpiece by electrical discharges, wherein the electrode workpiece and an electrode tool are displaced relative to each other at least in one slant direction disposed at a predetermined angle with the principal axis of feed of one electrode relative to the other, the machining gap between the electrodes is set at a finite value such as to maintain predetermined machining conditions, consecutive machining passes are effected and, at the end of each machining pass, the slant direction of feed is displaced as soon as the amplitude of relative displacement between the electrodes reaches a predetermined limit value, and such limit value is changed from one pass to the next. For the purpose of removing material from the workpiece to an equal depth on all the surfaces of the workpiece in the course of a finish machining pass, the electrodes are displaced relative to each other in slanted directions which are modified as soon as the amplitude of displacement reaches a predetermined limit value whose envelope is a hemisphere. As a result of effecting such consecutive relative displacements of the electrodes in a specific predetermined sequence while maintaining the density of the machining current at an optimum value, the total duration of the finish machining operation is considerably reduced as compared to the prior art.

Process and apparatus for machining by electrical discharges along a

A method and apparatus for cutting a workpiece by electrical discharges by means of a travelling wire electrode according to a path determined by a numerical control program without reducing the machining speed or the current flowing into the wire electrode. At least one of the support and guiding members of the wire electrode is displaced relative to the workpiece along a path resulting from shifting each point of the desired cutting path a predetermined distance in the direction of machining along a tangent to each point of such path. The angle between the tangent at each point of the path relative to the coordinate axes is determined, and each point of the path is shifted relative to the programmed path along coordinates having values proportional respectively to the sine and cosine of the angle.

Process and apparatus for electrical discharge machining by means of a

An EDM method and apparatus for cutting a workpiece by a wire electrode in the form of a metallic tape or wire, in which the traction exerted on the wire electrode by the mechanism feeding the wire electrode in the machining zone between the wire electrode and the workpiece is modified momentarily, and the variation of machining rate caused by the momentary modification of the force of traction exerted on the wire electrode is detected. The direction in which the machining rate is changed provides an indication of the effect, on the wire electrode, of the transverse forces which deflect the wire in the machining zone, relative to its longitudinal axis. The direction in which the machining rate varies is used to select the direction in which a predetermined machining parameter affecting the transverse forces applied on the wire electrode is changed, such as to maintain the wire electrode properly aligned along its longitudinal axis.

Method and apparatus for straightening the wire electrode of an

A process and apparatus for an EDM machine provided with an overcut drive mechanism for orbiting the electrode tool relative to the electrode workpiece in a cyclical motion, comprising a control for the orbital mechanism which varies the velocity of the cyclical orbital motion as a function of the difference between the orbital path actually obtained and a reference orbital path, such as to simultaneously provide a control of the workpiece shape and maintain the machining gap and, therefore, the machining current substantially constant.

Electrical discharge machining apparatus and process with controlled

A control system, in an EDM machine, for simultaneously displacing the electrode tool and the electrode workpiece relative to each other along both an axis of penetration of the electrode tool into the workpiece and a translation motion in a plane perpendicular to the axis of penetration of the electrode tool into the workpiece. The control system consists of logic circuitry providing a variable signal obtained by integrating as a function of time the difference between a signal representative of the machining condition and a reference signal, apportioning the variable signal between a first and a second electrical signal and interrelating the apportionment with a control of the relative position of the electrodes along the axis of penetration and of the eccentricity of the relative translation movement, respectively, as a function of the first electrical signal and of the second electrical signal.

Apparatus for controlling the relative motion of the electrodes in

The present invention is an EDM (Electrical discharge machining) process and apparatus for machining an electrode workpiece by means of an electrode tool wherein the electrodes are displaced relative to each other along a principal feed axis while, simultaneously, the electrodes are displaced relative to each other along an orbital path in a plane perpendicular to the principal feed axis, such as to produce between the electrodes a three-dimensional translation motion, and for providing between the electrodes an average machining gap wider than the gap width sustaining electrical discharges. The invention provides a control of the amplitude of the relative translation motion of the electrodes while displacing the direction of said motion as soon as a predetermined orbiting path limit is reached such as to allow a rapid increase of the gap between the electrodes when the electrode tool is retracted.

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Geneva, Switzerland

Alain Wavre