FR2464784A1 - METHOD AND APPARATUS FOR ELECTRO-EROSION MACHINING - Google Patents

Abstract

METHOD AND APPARATUS FOR CONFORMING BY ELECTRO-EROSION A CONTOUR IN A ROOM BY MEANS OF A CIRCULATING WIRE ELECTRODE 1. THE APPARATUS INCLUDES GUIDING MEANS 2A, 8C CARRIED BY A TOOL HEAD AND A CURVED LINEAR GUIDING SURFACE OF THE ELECTRODE TO CONSTITUTE AT LEAST PART THE WORKING SURFACE, MEANS FOR PASSING A WORKING CURRENT , FIRST CONTROL MEANS FOR MOVING THE TOOL HEAD IN TRANSLATION RELATIVE TO THE PART SO THAT THE ELECTRODE MOVES FOLLOWING A PREDETERMINED ROUTE IN THE PART, AND SECOND CONTROL MEANS 18, 19, 20 TO DO TURN THE GUIDANCE MEANS IN RELATION TO THE PART AROUND A ROTATION AXIS INTERSECTING THE WORKING SURFACE IN A PLANE DEFINED BY THE ELECTRODE CIRCULATING ON THE GUIDING SURFACE.

Description

1 2464784

  The invention relates to electrical machining techniques in general, that is to say machining by electric discharges, electrochemical machining and electrochemical discharge machining, and it provides more particularly an electrical machining method and an apparatus for contouring a three-dimensional surface in a three-dimensional configuration part or contour on the surface of a

  piece, by means of a circulating wire electrode.

  In his French patent application NO 79 24 919 filed

  On October 5, 1979, the Applicant pointed out that the

  electric machining, when applied for

  conform to a three-dimensional outline or a pattern of over-

  face in a room, commonly use an electrode-

  three-dimensional tool to achieve the desired contour or surface pattern. In addition, a multiplicity of such massive electrodes, identical configurations and sizes, or the like must be prepared to compensate for wear.

  that electrodes or tools undergo during the course of

  erosion, or in the interest of reducing the machining time to obtain machining precision and finish

  desired surface area. The preparation of these multiple electro-

  precisely shaped is obviously long and lab-

laughing.

  In the Patent Application mentioned above, it is de-

  Written an electrical machining device such as a sculptor or planer milling machine to conform the contour of a three-dimensional surface in a room. The described apparatus comprises a continuous elongated electrode of wire or the like (wire or wire-electrode), wire feed means for axially circulating the wire from supply means to recovery means, a carrier piece of clean room to receive the piece, wire guide means carried by a tool head and juxtaposed to the workpiece to position the running wire under tension in relation

  machining equipment with the equipment, power supply means

  this to electrically excite the wire and the piece in order to

  electrically eroding the material from the workpiece in a fluid filled machining gap, and machining feed means for relatively moving the tool head and the workpiece carrier to cause scanning ,

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  by the wire running on the guide means, the surface of a predetermined area on the workpiece, according to a predetermined machining path, to conform in the workpiece the three-dimensional surface contour, the guide having a surface of guiding wire, grooved and non-conductive electricity, adapted to receive the wire in circulation so that it is substantially in

  look at the surface of the juxtaposed room.

  The guiding means may comprise one or more

  rotary or non-rotary type guiding elements whose configuration

  The wire guiding ration may be adjusted to variably adjust the length, width and stroke surface of the juxtaposed wire to the surface of the workpiece.

machining relationship.

  The machining feed means may comprise first control means for moving the tool head towards and away from the workpiece along the Z axis, second control means for moving the workpiece carrier into a plane along the X and Y axes which are, with the Z axis, perpendicular two by two. Preferably,

  third control means can be provided,

  taking rotary means to rotate the tool head about the Z axis so that the transverse feed direction of the wire can always be perpendicular or, more generally, form a predetermined angle with the surface being machined of the room. For a current planing operation, the second and third control means are used, while milling and carving operations require the implementation of the first, second and third control means, in connection with each other. A standard numerical control can

  be used to operate the controls and

  void sweeping by the tool head of the workpiece surface, according to the instructions of a program in memory

  predetermined to correspond to a desired scan path.

  In addition, fourth control means may be provided to allow an inclination of the tool head according to

  a variable angle to the room so that the head-

  tool and the piece are relatively movable having

five degrees of freedom.

  It was also pointed out that means are prefer-

  intended to communicate in addition a high vibration

  frequency in the audible range or ultrasound, directly

  or indirectly, for example by means of a machining agent, the wire flowing in the guide means which is juxtaposed to the workpiece. The vibration may be provided by means of an electromechanical transducer or an element

  magnetostrictive but, advantageously, it can be

  in conjunction with electrical machining pulses applied across the machining gap between the wire and the workpiece. More specifically, a resonant circuit is connected to the machining interval, and whose resonance frequency is in agreement with the frequency of the oscillation

  generated at the machining interval.

  An important object of the present invention is to provide a method and an improved electrical machining apparatus, such as milling machine, sculptor or planer, allowing

  to easily conform in a room a three-dimensional outline

  The invention also provides a method for providing a method of electrical machining for milling, carving or planing, and an apparatus for allow the conformation of a complicated three-dimensional surface contour or pattern

  in a room with increased efficiency.

  According to a first aspect, the invention provides a method

  to convert by electro-erosion a three-dimensional contour

  sione in a room using an elongated electrode con-

  [0018] a stream continuously axially flowing from supply means to return means, so as to continuously renew a machining surface of the juxtaposed electrode in electro-erosion machining relation with the workpiece; characterized in that it comprises the steps of: supporting the continuous elongated electrode flowing between the supply and recovery means by guide means carried by a tool-head and having a linear-juxtaposed curved guide surface to the workpiece for guiding the elongated electrode flowing over at least a portion of the curved guiding surface, thus constituting

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  at least in part said machining surface, at least a portion of said elongate electrode flowing on the guide surface; passing an electro-erosion machining current between the elongated electrode and the workpiece through a

  machining center filled with fluid to remove

  from a part of the. piece juxtaposed to the machining surface of the elongate electrode; and translating the tool head relative to the

  piece so that said part of the electrode allon-

  The moving member moves along a predetermined contour path in the workpiece while rotating said guide means.

  relative to the part around an axis of rotatinn inter-

  securing said machining surface or the axis thereof in a plane defined by the elongate electrode flowing and guided on said guide surfaces, thereby conforming said

outline in the room.

  The guide means can be attached to the tool head

  or, alternatively, may be rotatably mounted about the axis

  mentioned above of the head-tool. When the means of

  are attached to the tool head, the latter is rotated

  relative to its crew, for example an arm

  by a cylinder of the machine itself. The means of supply

  tured recovery of the circulating elongated electrode are

  both, appropriately carried by the head-tool.

  More specifically, the contour path may be a curved line along which a groove of a depth and width corresponding to the thickness of the elongated electrode is to be shaped in the workpiece. Then, the guide means are pivoted so as to maintain said plane of the elongated electrode always oriented in the direction of advance of said translational movement between

  the tool head and the workpiece, along said curved line.

  The translational movement between the tool head and the workpiece can be in the direction of the depth of the workpiece and the latter can be rotated about said workpiece axis.

  rotation relative to the head-tool.

  Said guide means are rotatably mounted on the tool head about said rotary axis which is substantially

  perpendicular to the surface of the room.

  According to another characteristic of the first aspect of the invention, the continuous elongate electrode is supported between the supplying and taking-up means by said guiding means as a primary guiding element and furthermore by an additional guiding element carried by the tool head, the method further comprising the steps of changing the relative positions of the element

  additional guide and the primary guide element

  mayor during a conformation contour operation.

  In particular, the relative positions of the additional guide member and the primary guide member

  are modified to substantially change the inclination

  the shape of the machining surface with the surface of the workpiece, or to change the effective surface area of the workpiece

  machining surface relative to the workpiece surface.

  Here again the contour path can be a line indi-

  curved along the path of which is conformed in-the

  a groove of the same width and depth

  laying at the thickness of the elongate electrode. Then, the tool head is pivoted about said rotational axis so as to maintain the plane defined by the elongated guided electrode

  primary and secondary guiding elements,

  days oriented in the direction of advance of said translational movement between the tool head and the workpiece, along

the curved line.

  The translational movement between the tool head and the workpiece can also be towards the depth of the workpiece. The latter is then rotated around said

  rotary axis with respect to the tool head.

  The primary guide element can be attached to the tool head and

  the latter is then rotated about said rotary axis which is sensi-

  perpendicular to the surface of the room.

  According to a second aspect, the invention

  IEC 60050 - International Electrotechnical Vocabulary - Details for IEV number 841-21-21 Electrodisplacement of a three-dimensional contour in a workpiece by means of a continuous elongated electrode continuously conveyed from supplying means to recovery means, thereby continuously renewing a surface of electrode machining

  juxtaposed with the workpiece in electro-machining

  erosion, this apparatus being characterized in that it comprises guide means carried by a tool head and a curved linear guide surface to constitute at least in part said machining surface of the electrode

  at least a portion of the elongated electrode

  pressing on said guide surface; power supply means for passing an electro-erosion machining current between the elongate electrode and the workpiece through a fluid-filled machining gap to remove material from a portion of the piece juxtaposed to said machining surface of the elongate electrode;

  first control means for moving in trans-

  pouring the tool head relative to the workpiece such that said portion of the elongated electrode moves in a predetermined contour path in the workpiece; and

  second control means for rotating the

  said guide means relative to the workpiece around a rotary axis intersecting the machining surface in a plane defined by the elongated electrode circulating on said surface

guidance.

  In particular, the guide means can be fixed to a head-tool and the latter is then adapted to be pivoted about said rotary axis by the first means

  control. However, this is not essentially

  and the guide means can then be adapted to be rotatable relative to the tool head about said rotary axis. The means of supply and recovery are also

  both advantageously carried by the head-tool.

  This, however, is not essential, however.

  The supply and recovery means can be mounted on a column of the machine from which extends

  an arm to carry the head-tool over the room.

  According to another characteristic of the second aspect of the in-

  In addition, the apparatus further comprises a secondary guiding element cooperating with said guiding means.

  as primary guiding element to support the electri-

  continuous elongated trode between the means of supply and

  recovery, and means to change the positions

  of the secondary guide member and the primary guide member during a shaping operation

an outline.

  The invention will be well understood on reading the

  detailed description which will follow, given as an example

  ple, and in view of the drawing in which: - Figure 1 is a plan view partly in section and also in perspective showing the apparatus according to the present invention; FIG. 2 is a side view partly in section and schematic of the apparatus shown in FIG. 1; - Figures 3 and 4 are sectional views of the means

  guidance for explaining the principles of

  deny primary and secondary guiding elements according to the invention as applied to an example of conformation of a three-dimensional contour; Figure 5 is a sectional view of the guide means for explaining the mode of operation of the apparatus according to the invention applied to the conformation of another three-dimensional contour; FIG. 6 is a plan view of an example of an outline piece to be followed by the tool head and the moving part, relative thereto according to the method of the invention;

  FIG. 7 is a sectional view showing a diagrammatic

  a wire electrode circulating on guide elements for carrying out the contour conformation operation along a path shown in FIG. 6; and FIGS. 8 and 9 are sectional views schematically illustrating other examples of contour conformation.

  dimensions, which can be achieved through the

  assigned to the apparatus according to the invention.

  1 and 2. An apparatus according to the present invention applies a continuous elongated electrode 1 of wire or the like (wire or wire-electrode) of copper, brass or the like used in common machines of the present invention. Circumferential wire or cut wire discharge machining having a thickness of 0.05 up to 1 millimeter in diameter. The wire 1 is supported by a main guide roller or slide 2 of non-conductive material of the elect to form a curved elongation disposed at an end portion 3a projecting from a tool head 3 which carries a 4 of the wire supply reel 4 and 5 of the wire recovery reel, as shown, and also has control rollers 6a and 6b (capstan and support roller) e braking rollers 7a and 7b mounted on the

  head with auxiliary guide rollers 8a, 8b and 8c.

  The control and braking rollers 6a, 6b and 7a, 7b are controlled so that the wire 1 is unwound from the supply reel 4 and is then wound on the

  reel 5 and, on the path between them which

  takes a U-shaped path on the guide rollers 2

  machining, circulates continuously at a predetermined speed.

  mined and under a suitable voltage. Although this is not shown, the roller or the slide 2 constituting the guide means of the wire for machining purposes, can be conformed with

  a groove for receiving the wire on its periphery, a

  and a width such that most of the wire 1 can be exposed. When the roller 2 is rotatably mounted on a shaft 9 at the end 3a of the tool head 3, it is rotated, and the wire 1 is driven into the groove. When the slide 2 is fixedly mounted at the end 3a of the tool head 3, by means of a bolt 9a and a nut 9b (FIG. 2), the wire 1 passes by sliding in the groove on

the slide 2.

  The tool head 3 comprises a main frame 3b having an end projection 3a and a fastening flange 3c fixed

  to the main frame 3a. A pair of 3d and 3rd consoles extend

  From the flange 3c support the rotary shafts 4a and 5a of the reels 4 and 5 for supplying and taking up the yarn, respectively. The shafts 4a and 5a carrying the coils 4 and 5 are mounted in split bearings 4b and 5bpxentents at the lower end of the consoles 3d and 3e, by means of hinges 4c and 5c, respectively. The shafts 4a and 5a are driven with a suitable torque by a motor 10a (FIG. 2) mounted on the rear face of the main frame 3b.

  to entrap the coils 4 and 5 and to make it possible to

  perform supply and recovery functions. The wire 1 flows smoothly over the braking rollers 7a, 7b, the auxiliary guide roller 8a, the auxiliary guide roller 8c, the main guide roller or slide 2, the auxiliary guide roller 8d, the capstan and the support glands 6a and 6b. The coils 4 and 5 are also equipped with levers 4d and 5d which can be locked to prevent their rotation when the machine does not work. Referring to FIG. 2, other control units 10b and 10c are shown; they communicate a suitable torque to the braking rollers 7a and 7b and control the

capstan 6a, respectively.

  According to an important feature of the invention, the main guide 2 supporting the wire 1 along its guide surface 2a to place the la la of wire which

  circulates in machining relation with a part (not shown).

  1 and 2), is arranged to be rotatable about a vertical axis intersecting a center

  curved guide surface 2a so that the direction

  the advance of the wire extension may change by

  relative to the workpiece during a given machining operation.

  This can be achieved in the device shown in FIG.

  seeing the rotating tool-head 3 around such an axis or a

parallel axis.

  To do this, the flange 3c of the head-tool 3 has a central bore 3f in which is arranged in a fixed position

  a rotary shaft 11 which can be screwed into the main frame

  cipal 3b. The rotary shaft 11, thus fixed to the tool head 3, extends through a housing 12 slidably mounted on the flange 3c as shown or not in contact therewith, and which is fixed by means of bolts 13 to a plate 14 which, in turn, is mounted on an arm of the machine itself (not shown). The shaft 11 is mounted between the plate 14

  and the casing 12 by means of bearings 15 and 16 in order to

  rotatively carry the tool head 3. A stepper motor 17 equipped with an encoder 18 is provided inside the bbxtier 12 and is driven to rotate the shaft through gears 19 and 20. Thus, the head-tool 3 or the main frame 3b supporting at its lower end 3b

  the main guide element 2 pivots around the armature

bre 11.

  For the device shown, the guide assembly of the wire comprising the auxiliary guide rollers Sa, 8b and 8c, is adapted to hold the wire 1 so that it circulates in a fixed plane relative to the main frame 3b (Figure 2) and coaxially or parallel to the rotary shaft of the tool head 3. This device is desirable in the interest of the ease of programming the rotation controls for the tool head 3 according to a pattern

  desired machining on a piece by the expension la of fil-

  electrode guided by the U-shaped machining guide surface 2a. According to an important feature of the invention,

  auxiliary element 8c (referred to above)

  below as a roller or subsidiary guide element) directly adjacent to the main guide element 2 is adapted to be movable relative to this main element

  during a given machining operation, when a length of

  The substantial amount of elongation of the guided wire 1 between them should serve as a machining electrode surface, so that the effective machining area can vary depending on a particular pattern to be machined on the workpiece, or

  be kept constant regardless of this pattern.

  In order to allow the change during the process of the position of the secondary guide roller 8c with respect to the main guide element 2, the roller 8c is connected by a connecting rod 21 to a piston rod 22 of a jack

  23 (Figure 2) hydraulic or oil, fixed to the surface pos-

  The operating fluid for the cylinder 23 passes through a four-way valve 25, comes from a pump 26 and is collected in a reservoir 27. The cylinder 23 is equipped

an encoder 28.

  The four-way valve 25 operates according to

  tructions programmed in advance of a machining control unit (not shown) so as to advance or retract the piston 22 of the cylinder 24, and to move the secondary guide roller 8c that it carries between the positions

  represented by lines in solid line and in line

  1, a displacement of the subsidiary guide 8c is detected by the encoder 28 and then converted into an electrical signal which is supplied back.

to the machining control unit.

  The tool head 3 as described above is rotatably mounted to the arm of the machine which comprises a power source (not shown) connected to the wire electrode 1, for example, via the auxiliary guide roller Sa on the one hand and to the part on the other hand, and a fluid supply unit (not shown) to provide a

  machining agent, for example dielectric water or

  electrical conductor, up to the main guide zone 2. A high density EDM current is

  so between the expanse of yarn and the piece in the inter-

  machining valve filled with fluid, to remove material from the workpiece. The stepper motor 17 (FIG. 1) and the valve

  25 (Figure 2) are controlled by instruc-

  electrical supplies provided by a numerical control of the machining control unit. The machining advance assembly further comprises a crew piece., Clean to support

  the piece, and stepper motors to move in incremental

  piece crew in an X-Y or horizontal plane and a tool crew to support the arm of the machine,

  and a stepper motor to incrementally move the head-

  tool 3 vertically or along the axis Z. It is desirable that the la la range of wire is guided on the main guide 2 so as to present a surface

  increased effective machining during a machining operation.

  swimming in various situations. If, for example, the tool 3 is oriented in the direction of the X axis and must be advanced in the same direction to form a shallow groove of small width corresponding to the thickness of the wire on the surface of a workpiece (In FIG. 3, such a groove bears the reference a and it is made on a part 30), then, when only the main guide 2 is the only element to guide the wire 1 and to form a machining area 1la juxtaposed with the part 30, it is seen that the portion of the wire la lying substantially below the surface 30a which corresponds to the angle at the center, can provide the effective machining surface which may be too small for the passage of the machining current, or can limit the actual current

  machining; this results in a machining time that is too long.

  In this case, the subsidiary guide roller 8c can, according to the invention, be moved to extend the wire 1 in the direction of its advance or of the X axis, so that the wire extent 1a is juxtaposed on its extended length 1 to the workpiece 30 with a small angle of inclination with respect to the surface 31 of the workpiece. The machining surface

  resulting increase is likely to

  centering electrical discharges while actually increasing the average machining current, thereby reducing the machining time. The length 1 of this increased extent can be controlled by the position of the guide roller 8c

  subsidiary moved. In this case, if we consider that

  crunch of the machining movement not to ls in the direction

  of the X axis is dx, the reduction of the length of the in-

  machining time is expressed by sin 5.dx. Since sin 6 is less than 1 and e is small, we see that we only get a small variation of the dimension

  the machining interval, which ensures a stable

  increased machinability. In this way, the position of the subsidiary guidance element 8c is controlled during

  of the machining operation according to an inser-

  the depth of cut or cutting pattern of

forming or profiling.

  A cutting pattern, for example defined by a combination of a cylinder 32a and a spindle-shaped projection 32b, as shown in FIG. 5, can be machined easily and efficiently in a workpiece 32 with a device in which auxiliary guide element 8c can move relative to the main guide element 2 during a machining operation. In this case, the workpiece 32 can be rotated about the axis of symmetry of the -process or Z axis shown while the main guide 2 is moved

  to take positions 2-1, 2-2, 2-3 and 2-4 successively. The subsidiary guide 8c can then be moved successively in the

  X-Z plane to take positions 8c-1, 8c-2, 8c-3 and 8c-4 as shown while progressing the removal of material on the part. A minimal machining surface of

  the breadth of wire is thus maintained to allow the completion

  the desired machining operation with increased efficiency; a

  satisfactory machined surface quality is obtained.

  The particular construction mode of the tool head 3, especially the configuration and arrangement of the individual guides shown, the support structure and the positioning mode of the subsidiary guide element, as well as the mode of movement thereof , can obviously be modified by those skilled in the art. In addition, the wire supply and return coils, the braking rollers and / or the capstan and the support rollers may be separated from the tool head 3, for example on a column of the machine which supports the machine. arm that extends over the room to carry the head-tool. The tool head 3 can then carry only the main guide element 2 and the subsidiary guide or guides 8c with or without the

  auxiliary guide rollers 8a and 8b for receiving the elec-

  trode 1 wire supplied from the column area and to return this electrode in this region for recovery. It is desirable, as mentioned above, to arrange the main guide 2 or the tool head 3 rotatably during a given machining operation on the vertical axis intersecting with the lowest position or return point of the wire 1 or the expange 1a of wire guided by the main guide 2, so that the plane of reversal of the wire 1 (U-shaped) coincides with the direction of its relative advance or advance of the head-tool 3 compared to the

  piece. Thanks to this, the efficiency of the device is consid-

significantly increased.

  For example, it is considered that, as shown in FIGS. 6 and 7, grooves must be machined in a part

  shallow and curved, shallow in width, correspon-

  to the thickness of the wire electrode 1, moving the wire electrode 1 along a path 35b with respect to the workpiece 35. Then the workpiece 35 can be fixedly mounted. on a rotary table which, in turn, is movably mounted on an X-Y cross table, the two tables providing

  thus a possibility of positioning in three dimensions.

  But this not only makes the movement of the room extremely

  However, it only allows the processing of a relatively small workpiece and its machining, with respect to the size of the machine itself and the cross table. In addition,

  very complicated and tedious programming is born

  necessary. It is now considered that the tool head 3 is fixed in such a way that the main plane of the main guide 2 or the plane of the wire 1 guided by this guide is in the XZ plane which comprises the X axis and the XY plane orthogonal to this one, the cusp or lower position

  the electrode of the wire electrode being originally 0, and that the

  swimming is carried out according to the -ABC curve represented. In this case, when the region of point B is machined, it is necessary to simultaneously complete the rotational movement of the workpiece with the rotary table until the tangent TB at point B is parallel to the X axis and the translation of the workpiece 35 until the point coincides with the origin 0. It is clear that the combined movement is extremely complex and can not be grasped immediately or intuitively. In addition, the rotation of the workpiece 35 may occur at a point remote from the origin 0 and it is then necessary, with the transverse table, to maintain a considerably larger space above the table.

  than the space usually required to allow the

  of the X-Y transverse table. Moreover, moving the piece along a long and complicated path requires

  extremely complex and time-consuming programming for

  move the workpiece in relation to the fixed tool head.

  According to the invention, only a translational movement in the XY plane is applied to the workpiece 35 so that the point B on the machining curve ABC can always coincide with the cusp of the thread or with the origin 0 then that the tool head 3 is simply rotated to rotate the main plane of the main guide 2 or the plane of the la wire extent around the vertical axis which includes the cusp or around the Z axis if although the tangent

  TB can always be in the main plan of the main guide

  cipal 2 or the plane of the expanse of wire. In this way, the machining process becomes clear immediately or more intuitively. The rotation control of the main guide is extremely simple and the numerical programming required for this purpose is practically not subject to error. In

  In addition, the number of programming steps is considerable-

  reduced and, given that the path of movement of the

  piece is reduced, the programming is finally simplified.

  Finally, just the space required for the operation of the X-Y transverse table is enough above the table, which

  makes it easy to process and machine a comparative part

more importantly.

  In the embodiment of the apparatus according to the

  1 and 2, the rotation of the main guide 2 is obtained by the rotation of the rotary shaft 11 so that the tool 3 carrying all the elements in the path of the wire 1 from the supply reel 4 until to the recovery coil 5 is rotated as a structural unit about the axis. It will be appreciated that the structure may be modified to only allow a portion of the tool head which carries the main guide 2 to

  rotate according to the present invention.

  It will also be understood that an improved cutting performance can be obtained by virtue of the assembly already described in which the subsidiary guide element 8c directly adjacent to the main guide element 2 is adapted to be displaced.

  under control so that varies its guide position of the wire.

  In Figure 6, it is considered that the zorm substantially right

  point A is being machined. The cylinder 23 is then

  the yoke 25 to cause the piston rod 22 to protrude, thereby increasing the angle of inclination of the wire sling between the main and subsidiary guides 2 and 8c, with respect to the Z axis. explain more

  an increase in the machining area is then obtained

  naked, which allows a larger average machining current

It is necessary to pass between the stretch of wire and the piece.

  This present device is also useful for the process of cutting a thin workpiece 36 as shown in FIG. 8 and for the cutting process of an inner rim 37a or cutting a threading hole 37b in a workpiece 371 as shown in Figure 9. Such a complicated profile can be

  conformed by means of relatively simple programming.

  The present invention is widely applicable for

  the exploitation of the principles of machining by electro-erosion.

  The terms "electro-erosion machining" and "electrical machining"

  must, as underlined above, be understood to include machining by electric discharges, machining

  electrochemical discharge and electrochemical discharge.

  The principles of these machining processes are well known

  and it should not be given a detailed explanation here.

  In the electric discharge machining, a succession of machining pulses is applied from a specially adapted generator between the tool electrode, for example a wire electrode, and the part across a gap. machining bathed by a dielectric liquid,

  for example distilled water. In electrochemical machining

  In electrochemical discharge machining, a high amperage electric current is applied as a unidirectional current or a series of polarized pulses so that the tool electrode is cathodic and the part is anodic. , across a machining interval bathed by an electrode 8 to remove

  material from the room under the electrolytic action

  that or a combination of the electrolytic action and

  the action of spark discharges.

  This provides an improved method and apparatus for electro-eroding a complicated or three-dimensional contour in a workpiece to overcome

  the difficulties encountered in the prior art

laughing.

Claims (16)

  A method for electro-eroding an outline in a workpiece by means of a continuous elongated electrode continuously circulating from supply means to return means so as to continually renew a machining surface of the electrode juxtaposed to the workpiece in electro-erosion machining relationship, characterized in that it comprises the measures of: supporting the continuous elongated electrode circulating between said supply and recovery means, by means of guidance provided on a tool head and having a surface   curved linear guide juxtaposed to the guide piece.   deriving the elongated circulating electrode at least on a portion of said curved guiding surface, thereby at least partially providing said machining surface with at least a portion of said elongate electrode flowing and guided on the guiding surface; to pass a current of machining by electro-erosion   between the elongate electrode and the piece across a   machining center filled with fluid to remove   from a part of the room juxtaposed with the over-   machining face of the elongate electrode; and translating said tool head relative to the workpiece so that said portion of the elongated electrode moves along a predetermined contour path in the workpiece while rotating the guide means relative to the workpiece around the workpiece. an axis of rotation intersecting the surface   in a plane defined by the elongated electrode cir-   guided guts on the guiding surface, thus conforming said contour in the room.   2. Method according to claim 1, characterized in that the guide means are fixed to the head-tool and are rotated by rotating the head-butt relative to said rotation axis.   3. Method according to claim 1, characterized in that said supply and recovery means are worn by the tool-head.   Method according to claim 1, characterized in that the contour path is a curved line and that the guide means is rotated so as to maintain the plane of the elongate electrode oriented in the direction of travel advance. in translation between the head tool   and the piece following the curved line.   5. Method according to claim 1, characterized in that the displacement in translation between the tool head and the workpiece is in the direction of the depth of the workpiece,   and in that the workpiece is rotated about said rotational axis relative to the tool head.   6. Process according to claim 1, characterized in that   that the guide means are rotatably mounted on the head   tool about said axis of rotation which is substantially   perpendicular to the surface of the room.   7. The method according to claim 1, characterized in that the elongate electrode is supported between the supplying and taking-up means by the guiding means as a primary guiding element and furthermore by a secondary guiding element carried by said tool tool, said method further comprising the step of changing the relative positions of the secondary guide member and the primary guide member during an operation conformation of the contour.   8. Method according to claim 7, characterized in that the relative positions of the primary and secondary guide elements are modified to substantially change the angle of inclination of the machining surface relative to on the surface of the room.   Method according to claim 7, characterized in that the relative positions of the primary guide elements   and secondary are modified to change the surface area tive of said machining surface.   10. A method according to claim 7, characterized in that the contour path is a curved line and in that the tool head is rotated about said axis so as to maintain the plane defined by the guided lead electrode   secondary and primary guiding elements,   days in the direction of travel in transla-   between the tool head and the workpiece along the curved line. 11. The method of claim 7, characterized in that the displacement in translation between the tool head and the workpiece is in the direction of the depth of the workpiece and in that the workpiece is rotated about said axis of rotation. relative to the head-tool.   Method according to claim 7, characterized in that the primary guide element is fixed on the tool head and in that the tool head is pivoted about said axis of rotation which is substantially perpendicular to the surface. of the room.   13. Apparatus for electro-eroding an electrode   turn in a room using a continuous elongated electrode   continuously flowing axially from supply means   to the means of recovery, so as to renew   continually a machining surface of the juxta-   applied to the workpiece in machining relationship, characterized in that it comprises: guide means carried by a tool head and a curved linear guide surface juxtaposed to the workpiece for guiding the continuous elongated electrode in circulation on at minus a portion of the curved guide surface to at least partially form the machining surface of the elongate electrode with at least a portion of the elongate electrode flowing over said guide surface; power supply means for passing an electro-erosion machining current between the elongate electrode and the workpiece across a fluid rectification interval to remove material from a portion of the piece juxtaposed to the machining surface of the elongate electrode;   first control means for moving in transla-   holding the tool head relative to the workpiece such that said portion of the elongate electrode moves along a predetermined contour path in the workpiece; and second control means for rotating the guide means relative to the workpiece about an axis of rotation intersecting the machining surface in a defect plane   by the elongated electrode flowing on the guide surface.   14. Apparatus according to claim 13, characterized in that the means GU! Jlag are attached to the tdta-tool ct and that the latter is adapted to rotate about said axis of rotation under the action of said first control means. 15. Apparatus according to claim 13, characterized in that the supply means and the recovery means are provided on the tool head.   Apparatus according to claim 13, characterized in that it further comprises a secondary guide member cooperating with said guide means as an element.   primary guide for supporting the elongated electrode con-   between the supply and take-back means, and means for changing the relative positions of the secondary guide member and the primary guide member   during a shaping operation of said contour.