Device for erosion machining conical passages.

State of the art

0001In many areas of technology, it is necessary erode conical holes. For example, in Injectors or injectors of Fuel injection systems of internal combustion engines increasingly conical spray holes with diameters in the range used by a few tenths of a millimeter. Here, the Accuracy requirements both in terms of Diameter and the taper and the hydraulic Properties, such as the flow resistance, very high.

0002So far in the applicant for eroding is conical Drilling using a wire electrode, during the Eroding process is vibrated so that a free end of the wire electrode like a pendulum back and forth swings. As this pendulum motion not on a plane is limited, by the oscillating movement of the Wire electrode during the eroding process a conical Hole eroded out from the workpiece. Disadvantage of this method is that the conicity of the bore not is controllable, because it depends on many process parameters, which do not usually or only a very limited extent can be changed.

0003Another method used by the company Posalux is the wire electrode through the guide bore pass out a rotatable guide disc. The Guide bore and the axis of rotation of the guide plate include an angle greater than a 0 °. If the Sabot during the eroding process rotates, passes over the wire electrode has a conical surface, so that conical holes may be produced. A disadvantage of this method is that the conicity not regulated during the series production of bores can be, since the cone angle of the eroded hole by the angle, which the guide bore, and the Include rotational axis of the guide plate, fixed is. This also means that the cone angle only by Replacing the guide disk can be changed.

0004Also in this method, the tip of the Conical surface a large distance to the to machined workpiece. This distance prevents the Machining conical holes with small diameters.

ADVANTAGES OF THE INVENTION

0005In a first embodiment of an inventive Apparatus for eroding with an electrode and a Electrode guide and a support for the Electrode guide is provided that the Electrode guide to the bracket with a hinge bearing is stored and that at a distance from the hinge a Means for displacing the electrode guide into two Space directions is provided. In the inventive apparatus for eroding it possible, independent of other process parameters, the Taper of continuously and without eroding bore Retooling the device set. As a result, in the Repetitive Manufacturing the taper continuously on a predetermined target value can be regulated, so that the Variations are minimized within the serial production and identical workpieces of a series of nearly identical have hydraulic and geometric properties. also it is possible, at various conical bores of a Workpiece without re Erodiervorrichtung form various cone angles.

0006Furthermore, the device according to the invention is a relatively simple structure, so that in and of to existing EDM machine by replacing the Erodierkopfes which bearing the invention and Means for displacing the electrode guide comprising, can be replaced. This makes it possible, existing Production facilities in a very economical way to toughen.

0007claimed in the context of the invention Means for displacing the electrode guide, the Electrode guide by mechanical, hydraulic, pneumatic, magnetic or electric forces Deflect. The principle of the invention, with all these Variants can be realized. Which of these variants Preference will be given, depending on the other Boundary conditions and process parameters are chosen.

0008comprises in an advantageous embodiment of the invention the means for displacing the electrode guide a with the first electrode lead connected magnetizable ring, and a with the holder second magnetizable ring connected and more than distributed the circumference of the second magnetizable ring and its related coils. By this arrangement, it is possible by a suitable control of one or several coils the electrode guide in any Direction perpendicular to the longitudinal axis of the electrode deflect. Now, if by a suitable control of the Coil the electrode guide is deflected so that the in their guided electrode of a cone sweeps, can with the electrode produced conical holes will. Depending on the deflection of the electrode guide, the Cone angle of the conical bore continuously up to a deflected by the maximum value predetermined device will. This means on the one hand, that in a simple manner during a series production, the taper of the holes can be adjusted and the other part in a Workpiece conical holes with different Cone angles without retooling the invention Device can be produced.

0009A particularly simple control of the means for Deflection of the wire electrode is three coils to to connect a three-phase source. The by the three-phase Magnetic field caused runs at the frequency of the Three-phase current in a way that the desired electrode performs motion to a cone. By regulating the intensity of the current, or by regulating the frequency or a combination of these variants, the taper angle the tapered bore to be controlled. these must embodiments, the joint a restoring force , such that the electrode guide in their Initial length, when the means for Deflection of the wire electrode is not active.

0010Alternatively, the means for deflecting the Electrode guide also more about the extent of Electrode guide distributed include piezo actuators. Also Here, by appropriate controls of one or more these piezo actuators, the electrode guide in each direction perpendicular to the longitudinal axis to deflect the electrode and thus any desired cone angle of the conical Hole set.

0011Particularly simple design embodiments of the Invention provide that the means for deflecting at least one screwed into the mounting screw includes, and / or that the means for deflecting comprises at least one compression spring, wherein the at least a compression spring, the electrode lead in contact with the holding screw. In this embodiment, the Taper a to be eroded hole continuously and very be precisely adjusted using the adjusting screw.

0012The hinge for supporting the electrode guide can at an advantageous embodiment of the invention as a membrane be carried out, which the holder and the Electrode guide play and hinged together connects.

0013Alternatively, the joint can for storage of Electrode guide and a ball joint with a cap on the electrode guide and with an abutment on the be designed holder. A particular advantage of this Variant is that by a suitable choice of the radius the dome of the pivot point of the electrode lead from the Electrode guide out can be shifted. Of the Fulcrum of the electrode guide coincides with the peak of the Cone-shaped shell together, the sweeps over the electrode to produce a conical bore. When the tip of Cone surface is displaced toward the workpiece, reduces the minimum diameter of the tapered bores. If the tip of the cone within the workpiece is, can even double frustoconical bores getting produced.

0014Alternatively, the joint also by between Electrode guide and holder arranged ring from a elastic material, in particular of an elastomer, be formed. Finally, it is also possible for the joint through to implement one or more leaf springs.

0015It is also conceivable and possible, the electrode guide hydraulically, pneumatically or by means of magnetic forces on the storing holder.

0016According to the invention can also be provided, the bracket and with it the electrode guide during erosion in to enable rotation. This is a very good roundness the conical bore guaranteed. Also need the Electrode are deflected only in one direction be able to produce a conical bore. These Deflection in one direction is particularly simple and well with a set screw and at least one compression spring.

0017Which storage and means for deflecting in concrete Application, preference is given, inter alia, depends by at the EDM and the other Production facilities existing from constraints. It can an inventive apparatus for eroding with each of said bearings are realized.

0018The electrode guide can be used as a junction or a round two-piece guide which the electrode in the radial Direction results without radial clearance or even jammed, be formed.

0019The roundness of the inventive device with the eroded holes can be further improved if a means for rotating the electrode is provided.

0020To be able to position the electrode, and also in Along the longitudinal axis of the electrode a feed To run, a feed device for the Electrode provided. Here, the feed device the eroding head and / or the wire electrode in all three Moving dimensions of space, so that not only a Advancing movement of the wire electrode, but also the Positioning the electrode relative to a workpiece with the claimed advancing device is possible.

0021Further advantages and advantageous embodiments of the Invention are the following drawings, their Description and the patent claims. Alone the drawing, the description and the claims Described features may, both separately and in any combination essential to the invention be.

drawing

0022Show it:<dl tsize="7" compact="compact"><dt>figure 1</dt><dd>a first embodiment of a A device according to the invention in longitudinal section;</dd><dt>figure 2</dt><dd>the first embodiment of a A device according to the invention in cross-section,</dd><dt>figure 3</dt><dd>a second embodiment of a A device according to the invention in longitudinal section and</dd><dt>figure 4</dt><dd>the second exemplary embodiment of a A device according to the invention in cross section.</dd></dl>

Description of Embodiments

00231 shows a first embodiment of a inventive apparatus greatly to erode simplified manner in longitudinal section. In a holder 1 is an electrode lead 3a and 3b for receiving the electrode lead 3a articulated. At this Embodiment, the electrode lead 3a slightly be replaced, for example, when other to a Wire size to be upgraded or if the Electrode lead 3a is worn. However, it is of Inventive idea also includes, if the recording and 3b the electrode lead 3a are integral.

0024The holder 1 is part of a not shown EDM. The parts of the unillustrated Eroding anyone skilled in the prior Art are therefore not explained in detail and known.

0025In the first embodiment shown in Figure 1 the articulated support by a membrane 5 of metal implemented, for example, on its outer diameter connected by a weld 4 fixed to the holder 1 is. Inside the membrane 5, in this embodiment with one end of the recording 3b for the electrode lead 3a Electrode guide 3 by means of a weld. 4 Through this storage, the electrode lead 3a has a Degree of freedom in the direction of the double arrow 7, and a Degree of freedom perpendicular to the plane. In other Words can 3a The electrode guide perpendicular to Longitudinal axis of an electrode can be deflected. 9 Of the Pivot point of the articulated bearing is shown in Figure 1 with the Numeral 11 indicated.

0026The electrode 9 is in a bore 13 Electrode lead 3a out in the radial direction. The Game between bore 13 and electrode 9 is shown in Figure 1 greatly enlarged.

0027A feeding device, not shown, the Electrode 9 among others in the direction of arrow 15 from the Electrode guide postponed 3a and again be withdrawn. Thereby, the wear of the Electrode 9 are balanced, and there may be a made feed movement during the eroding process will. In addition, the holder 1 and with it the electrode 9 by means not shown a Rotational movement be rotated about its longitudinal axis. This is indicated in Figure 1 by a curved arrow 17th By the rotation of the electrode 9 during the Eroding process is the roundness of the hole eroded improved. The mounting of the bracket 1 is in figure 1 not shown.

0028At the end of the recording 3b for the electrode guide 3a, which the membrane 5 is opposite to a first magnetizable ring 19 fixed 3b with the absorption and thus indirectly connected to the electrode lead 3a. On the same level of the first magnetizable ring 19 are distributed over the periphery a plurality of coils 21, 23 and 25 arranged, of which only the coil 21 is visible in Figure 1 is. By supplying current to the coil 21, a first Radial force F_r1 at first magnetizable ring be exercised. This is to the electrode lead 3a its membrane 5 opposite end in the radial Direction deflected.

0029In Figure 2 is a top view of the electrode 9, recording 3b for the electrode guide 3a and the Coils 21, 23 and 25 shown. This illustration it is clear that each of the coils 21, 23 and 25 through correspondingly energizing a radial force F_r1, F_r2 and or F_r3 can exert on the magnetizable ring 19th This also means that by appropriate energization of the Coils 21, 23 and 25, the electrode lead 3a in each Direction deflected within the plane of Figure 2 can be.

0030When one supplies the coils 21, 23 and 25 with rotational power, creates a circulating with the frequency of the phase current Magnetic field that the first magnetizable ring 19 and with him the electrode guide 3a so deflects that they with its membrane 5 opposite the end of a performs circular movement. This means nothing other than that the electrode 9 a conical surface (Not shown) passes over, headed by Fulcrum 11 coincides.

0031Thus, it is possible, with the part of the electrode 9, which projects beyond the electrode guide 3, a cylindrical Bore to erode in an unillustrated workpiece. Depending on how strong the electrode guide 3a at its the Membrane 5 opposite end is deflected, the Cone angle of the conical bore infinitely adjusted will. This has the great advantage that during the adjusted manufacturing a series of cone angle steadily can be, so that a very uniform Manufacturing quality can be achieved. It is also possible on a workpiece without re inventive apparatus, the cone angle of two to make conical holes different.

0032To the magnetic fields generated by the coils 21, 23 and 25 to perform better, is between the coils 21, 23 and 25 and the bracket 1, a second magnetizable ring 27 provided.

0033The desired circular motion of the electrode 9 at the the membrane 5 opposite end of the electrode guide in this embodiment 3 is formed by a rotating Magnetic field caused. This rotating magnetic field in turn, by a three-phase, the order by the three 120 ° offset coils 21, is passed 23 and 25 on the simplest way be generated. To control the Deflection of the electrode lead 3a, and thus also the Electrode 9 lend themselves to two control strategies.

0034The cone angle can about the strength of the magnetic field be managed. When the rotational frequency of the magnetic field 3b outside the resonance range of the recording and the Electrode lead 3a is, taking the deflection of the Electrode lead 3a linear in magnetic field strength and thus the current intensity. This means that the angle of taper on easily controllable.

0035In a second control strategy, the taper angle can the frequency of the rotating field to be regulated. namely, the frequency of the rotary field at the resonant frequency of from Recording 3b, electrode lead 3a and membrane 5 formed vibratory system is approximated, taking the radial deflection to. If the invention operated device in the vicinity of the resonant frequency is, can possibly compact designs realized , since smaller magnetic forces and thus smaller coils 21, 23 and 25 required.

0036A combination of both control strategies is possible.

0037Figure 3 shows a second embodiment of a inventive device also greatly simplified and in longitudinal section along the line B-B (see Figure 4). In this embodiment, the holder 1 is rotatably stored. The bearings of the bracket 1 are connected to the Numeral 29 is provided. In the upper part the bracket 1 a pulley 31 is provided.

0038In addition to the holder 1, a drive shaft 33 is provided, the driven by an electric motor, not shown becomes. Via a belt 35, the rotational movement of the Drive shaft 33 to the pulley 31 and thus to the Holder 1, the recording 3b and the electrode lead 3a be transmitted.

0039The electrode lead 3a assumes, as with the first Embodiment, an electrode 9. The electrode 9 is shown much thicker in Figure 3, as they did in is the reality. The device is intended namely serve, inter alia, the smallest holes (not shown) to erode into a workpiece 37th These holes usually have a diameter of a few 10ths Millimeters.

0040On its workpiece 37 end facing the Recording 3b for the electrode guide 3 a Diameter extension on the partially spherical cap is trained. The dome-shaped portion of the Diameter extension recording 3b is connected to the Numeral 39 is provided. At its lower end, the Holder 1 on a conical surface 41, which abutment a represents for the cap 39 of the receptacle 3b.

0041With the help of a compression spring 42, which at one end to be a Paragraph 1 of the holder and the other end on a shoulder of the Electrode guide 3 is supported, the cap 39 in system is held on the abutment 41st At the the abutment 41 the opposite end of the holder 1 is a Screw 43 is present, the recording and thus 3b the electrode guide 3 in Figure 3 to the left side can deflect. By more or less reddish brown of Screw 43 can in the holder 1 thus the angle between the electrode lead 3a on the one hand and the Bracket 1 on the other hand are set.

0042In order for the recording 3b for the electrode guide 3a always in Plant remains on the screw 43, is opposite the Set screw 43 at least a compression spring 45 is provided. This compression spring 45 is in the shown in Figure 3 Embodiment in a blind hole 47 in the Recording 3b. The compression spring 45 is supported at one end in the radial direction against the recording and 3b at the other end against the bracket 1 from.

0043Figure 4 shows a section through the holder 1 and the electrode guide 3 along the line AA (see Figure 3). It is clear from the synopsis of the figures 3 and 4 that in this embodiment, two compression springs 45 are present, with the longitudinal axis of the adjusting screw 43 each form an angle of about 120 °. Thereby it is ensured that the receiving 3b for the Electrode guide 3 is always in contact with the screw 43 is held and can not move laterally.

0044In the embodiment of Figure 3 is the Center 11 of the dome 39 where the electrode 9, the Surface of the workpiece 37 contacts. The center 11 of the cap 39 and the fulcrum of the recording 3b for the Electrode lead 3a thus fall coincide. This means that, when the electrode lead 3a by means of the Screw 43 is deflected relative to the holder 1 and then, the holder 1 is rotated, the perforated spray produced by the electrode 9 (not shown) in the workpiece 37 a conical shape having. The conical bore has its smallest Diameter at the top of the workpiece 37th

0045When the workpiece 37 closer towards the bracket 1 is moved, the center 11 of the cap 39 can also lie within the workpiece 37th Thereby, it is also possible to produce conical holes, the largest Diameter is located on the underside of the workpiece 37th Likewise, it is possible to double frustoconical bores to erode when namely the center of the cap 11 39 between the top and bottom of the workpiece 37 is.

0046The second illustrated with reference to Figures 3 and 4 Embodiment is both very simple in construction and provides many degrees of freedom in manufacture. These degrees of freedom come to bear particularly positive, when smallest holes whose minimum diameter about equal to the diameter of the electrode 9 is conical are to be produced.