ELECTROCHEMICAL PROCESSING OF A WORKPIECE

Description

[0001] The invention relates to a system and method for the electrochemical machining of a workpiece, in particular a gas turbine component.

[0002] Electrochemical machining (ECM) is a shaping process for machining workpieces, which can be used particularly advantageously for machining complex surface shapes and / or difficult-to-machine materials. The process utilizes the anodic oxidation of the material to be machined. A working electrode is positioned at a distance from the surface to be machined, an electrolyte is provided in the gap between the surface to be machined and the electrode, and by applying an electrical potential between the electrode and the workpiece to be machined, the workpiece material is dissolved by anodic oxidation and transferred into the electrolyte. This results in material removal that depends on the potential conditions in the machining gap.These are in turn influenced by the gap width, so that a three-dimensional shape of the working electrode with correspondingly different distances between the working electrode and the surface to be machined leads to a shape-dependent removal rate. This allows the shape of the working electrode to be imprinted or reproduced on the machined surface.

[0003] Electrochemical machining can be performed not only continuously but also in pulsed form, where a continuous current flow is not established, but rather a large number of current pulses are applied consecutively. This type of process is also referred to as PECM ("pulsed electrochemical machining" or "precise electrochemical machining").

[0004] Typically, the working electrodes are moved back and forth in a sinusoidal rhythm. The speed during electrode removal should be selected to ensure that cavitation does not occur between the working electrode and the workpiece. Cavitation should be avoided whenever possible, as the workpiece is damaged by the localized removal of metal particles. These metal particles, which then remain in the gap, can also cause a short circuit between the tool and the workpiece.

[0005] International patent application WO 2012 / 152254 A1 discloses a machine for electrochemical metalworking, which comprises an ECM module mounted on the base body for linear displacement but not rotation. US patent application US 2008 / 0272957 further discloses a machine for electrochemical machining of tandem blisks, which comprises an ECM module mounted on the base body for linear displacement but not linear displacement. This application discloses the features of the preamble of claim 1.

[0006] An object of the present invention is to improve the electrochemical machining of a workpiece, in particular a gas turbine component.

[0007] This object is achieved by a system having the features of claim 1. Claims 12 and 13 protect a method for electrochemically machining a workpiece using such a system. Advantageous further developments are the subject of the dependent claims.

[0008] One aspect of the present invention relates to a system having the features of claim 1.

[0009] The term "movable" refers to any form of movement. This includes, in particular, linear, circular, parallel, and / or elliptical paths. Superimposed movements of these various paths are also conceivable.

[0010] The advantage of the zero backlash is that the drive's movements are transmitted directly to the tool. This allows the tool to follow the drive's movement essentially without delay. Eccentric torque motors, spindle motors, and / or piston motors can be used as the drive. In one version, the motor allows for continuous feed and enables a movement oscillation of the electrodes (changes of direction of rotation per second) of preferably at least 10 Hz and / or at most 60 Hz.

[0011] In one embodiment, the tool is attachable, particularly detachable or replaceable, or permanently or stationary, to a tool holder, preferably mechanically connected to the frame and / or drive. This has the advantage that the tool can be replaced more quickly without having to dismantle the drive mechanism, which is then preferably engaged or hinged to the tool holder.

[0012] In one embodiment, the drive has a drive axis from which a pivot axis is arranged at a distance, with a drive arm being hinged to the pivot axis. This has the advantage that with such a lever configuration, very high forces can be applied to the tool. Preferably, the drive axis and the pivot axis run parallel to one another. An eccentric shaft can be arranged on the drive axis, with the second axis of the eccentric shaft reflecting the pivot axis. In one embodiment, particularly in the case of a drive in the form of an eccentric torque motor, the eccentric shaft is formed, in particular manufactured, integrally with an output shaft of the drive.

[0013] In one embodiment, the drive arm is hinged to the tool and / or the tool holder. This has the advantage of implementing a direct drive with few mechanical links. The joint between the drive arm and the tool or tool holder can be designed as a flexural joint. In one embodiment, a flexural joint can generally comprise, and in particular consist of, spring steel assemblies arranged behind or on top of one another.

[0014] In one embodiment, the module comprises at least one rocker that provides the mechanical connection between the drive and the tool or between the drive and the tool holder. This has the advantage that the drive force can be redirected. This allows for a very compact design of the device.

[0015] In a further development, a push arm is articulated on the rocker, which is articulated on the tool and / or the tool holder. Both the joint between the push arm and the tool or the tool holder, as well as the joint between the rocker and the push arm, can be designed as a solid-state joint. In particular, the push arm can have a, particularly rectangular, push plate. The push plate can be constructed from several thin individual plates, which are preferably arranged behind or on top of one another.

[0016] In a further development, the drive arm and / or a support arm, which is connected to the frame, are articulated to the rocker. The joint between the drive arm and the rocker can be designed as a flexural joint. Additionally or alternatively, both the joint between the rocker and the support arm and the joint between the support arm and the frame can be designed as flexural joints.

[0017] In one embodiment, a solid-state joint can generally comprise, in particular thin, spring-laminated steel stacks, which are preferably arranged one behind or one on top of the other, in particular consisting of these. Likewise, it can comprise, in particular consisting of, a thick sheet. The desired stiffness can be adjusted via the thickness and / or the number of sheets.

[0018] One end of the support arm can be arranged at one end of the rocker and the push arm and the drive arm can then be arranged over the remaining part of the rocker, so that a one-sided lever is realized.

[0019] In one design, one end of the bearing arm is positioned on the rocker between the push arm and the drive arm. One arm of the rocker, to which the drive arm is hinged, represents the force arm, since the moving force is applied to this arm of the rocker. The other arm of the rocker, to which the push arm is hinged, represents the load arm, since the load to be moved (tool holder) is applied to this other arm of the rocker. With such a one-sided lever, very high forces can be transferred to the load arm in one design.

[0020] In one embodiment, the tool and / or tool holder is mechanically connected to the frame via at least one first pivot arm. This has the advantage that the tool is guided directly or indirectly via the tool holder on the frame.

[0021] In a further development, a second swivel arm is arranged in addition to the first between the tool and the frame, or between the tool holder and the frame. This offers the advantage that the tool has more precise and reproducible guidance, either directly or indirectly via the tool holder on the frame. If the two swivel arms also run parallel to each other and are spaced apart, a parallel swing arm can be easily implemented. Such a parallel swing arm offers the advantage that the tool holder can only move in one plane. This allows the tool holder to be positioned precisely and reproducibly at the required location.

[0022] Furthermore, both the joint between the push arm and the tool or the tool holder as well as the joint between the rocker and the push arm can be designed as a solid-state joint.

[0023] In one embodiment, the module comprises a second tool, a second tool holder, a second rocker and / or a second drive such that the second tool can be moved towards the first tool and / or towards the workpiece. This offers the advantage, particularly in the case of gas turbine components such as blades, that the workpiece can be machined from two sides simultaneously. This halves the machining time. In addition, with two oscillating tools (working electrodes) that approach the workpiece simultaneously from one side and the other, workpiece deformation can be minimized, i.e. the workpiece is machined synchronously from both sides. In particular, the stresses on the workpiece that are generated on both sides as a result of the electrolyte pressure cancel each other out. Asynchronous machining of the sides of the workpiece is conceivable. In one embodiment, this means that one side of the workpiece is machined alternately, then the other.

[0024] Preferably, the second tool, the second rocker and the second drive are arranged on the frame in mirror symmetry with respect to the first tool, the first rocker and the first drive.

[0025] One aspect of the present invention relates to a method for electrochemically machining a workpiece using a system according to claim 1. In one embodiment, a workpiece is first provided in step a.), then, in step b.), at least one tool is moved toward the workpiece at at least a first speed profile. Subsequently, in step c.), the workpiece is electrochemically machined. After machining, in step d.), the workpiece is moved away at a second speed profile.

[0026] In one embodiment, the first speed curve is independent of the second speed curve.

[0027] This is fulfilled if the absolute value of the first speed curve is not equal to the absolute value of the second speed curve. The first speed curve can be represented, for example, by a function v 1 (t'). The second speed curve can be represented, for example, by a function v 2 (t"). The following applies: |v 1 (t')| ≠ |v 2 (t")|, where t' stands for the period of time during which the tool is moved towards the workpiece and t" stands for the period of time during which the tool is moved away from the workpiece.

[0028] For purely sinusoidal movements of the tool, this condition is not met, since the magnitude of the speed curve in the period t' (left of the minimum) is equal to the magnitude of the speed curve in the period t" (right of the minimum). At the minimum, the speed is zero for a fraction of a second. At this time, the distance between the tool and the workpiece is at its smallest. Due to the function of the absolute magnitude, the speed curve in the period t' is mirrored on the vertical axis passing through the maximum and coincides with the speed curve in the period t".

[0029] In one design, the second speed curve is flatter than the first. This offers the advantage that higher speeds can be achieved when the tool approaches the workpiece than when it moves away from it. This avoids cavitation, especially during the withdrawal process, while still allowing the tool to approach the workpiece at very high speed. This offers the advantage that the flushing pressure can be further increased when the electrode moves toward it.

[0030] In one embodiment, the position of the tool remains unchanged in step c.). This has the advantage that the position of the tool is known during material removal, allowing defined voltages and currents to be applied. This significantly improves the surface quality. Alternatively, the gap between the tool and the workpiece remains essentially constant. This means that the tool is guided to the workpiece depending on the material removal rate. This would have the advantage of maintaining constant material removal rates.

[0031] In one embodiment, in step c), an electrical potential is applied between the tool and the workpiece at a frequency of 100 Hz to 3 kHz. This means that at 100 Hertz, the electrical potential is switched on and off 100 times per second. Preferably, rectangular electrical potentials are applied.

[0032] In a further advantageous embodiment of the invention, steps a.) to d.) are performed at a frequency (changes of direction of rotation per second) of at least 10 Hz and / or a maximum of 60 Hz. At 10 Hz, this means that the tool is moved back and forth ten times per second, allowing fresh, unused electrolyte to flow into the gap between the tool and the workpiece. This significantly increases the removal rate.

[0033] The ECM module for electrochemical machining of a workpiece comprises at least one electrode, a frame to which the electrode is mechanically connected, and at least one drive for moving the electrode, which drive is fastened to the frame, wherein the drive is in particular mechanically connected to the electrode in such a way that the latter can be moved without play.

[0034] In one embodiment, the tool is attached to a tool holder. Additionally or alternatively, the drive has a drive axis from which a pivot axis is arranged at a distance, wherein a drive arm is articulated to the pivot axis. In one embodiment, the drive arm is articulated to the tool and / or the tool holder. Additionally or alternatively, the module comprises at least one rocker which provides the mechanical connection between the drive and the tool or between the drive and the tool holder. In one embodiment, a push arm is articulated to the rocker and is articulated to the tool and / or the tool holder. In a further development, the drive arm and / or a bearing arm is articulated to the rocker. In one embodiment, the tool and / or tool holder is mechanically connected to the frame via at least one pivot arm.In a further development, a second pivot arm is arranged between the tool and the frame or between the tool holder and the frame. In one embodiment, the module comprises a second tool, a second tool holder, a second rocker, and / or a second drive such that the second tool can be moved toward the first tool.

[0035] In one embodiment, the method for electrochemically machining a workpiece comprises the steps a.) Providing a workpiece, b.) Moving at least one tool onto the workpiece at a first speed profile, c.) Electrochemically machining the workpiece, d.) Removing the tool (10; 60, 160) from the workpiece (2; 52) at a second speed profile.

[0036] In one embodiment, the first speed profile is independent of the second speed profile. Additionally or alternatively, in one embodiment, the position of the tool remains unchanged in step c.) or the gap between the tool and the workpiece remains essentially constant in step c.). In one embodiment, a pulsed current or a pulsed voltage with a frequency of 100 Hz to 3 kHz is applied between the tool and the workpiece during electrochemical machining. In one embodiment, steps a.) to d.) are performed at a frequency of up to 50 Hz.

[0037] The system comprises a base, in particular one that is resistant to environmental influences, and one or more workstations for the electrochemical processing of a workpiece.

[0038] In one embodiment, the system has at least one upstream workstation for the, in particular electrochemical or generative, production of a first outer contour of the workpiece and at least one further downstream workstation for the electrochemical production of a second outer contour of the workpiece, wherein the first has an allowance relative to the second outer contour. In particular, a downstream workstation can be provided or configured for electrochemical pulsed or PECM machining of the workpiece and arranged in series with the upstream workstation(s). An upstream workstation can be provided or configured, in particular, for electrochemical continuous or ECM machining of the workpiece. In one embodiment, two or more workstations for ECM or PECM machining are arranged in series in order to machine different areas of the workpiece.This allows a single workstation to be designed more compactly.

[0039] At least one of the workstations has a module for electrochemically machining the workpiece, which module comprises a frame and an electrode arrangement with at least one electrode which is mechanically connected to the frame, and a drive for moving this electrode which is fastened to the frame.

[0040] In one embodiment, the electrode arrangement comprises two electrodes that are mechanically connected to the frame, and two drives for moving these electrodes in opposite directions, which are attached to the frame. The module can, in particular, be a module described above and / or below.

[0041] The system comprises a workpiece holder for releasably securing the workpiece and a positioning device for moving the workpiece holder and the module relative to each other. The positioning device moves both the workpiece holder and the module, or is configured or provided for this purpose.

[0042] Accordingly, a method for electrochemically machining a workpiece using a system described here comprises the following steps: releasably fastening the workpiece to the workpiece holder, and moving the workpiece holder and / or the module relative to each other.

[0043] This allows the module to process different areas of the workpiece one after the other and / or selectively and can therefore be made more compact.

[0044] The positioning device comprises a base body on which the workpiece holder and the module are arranged. The workpiece holder is mounted on the base body, in particular by an actuator, in particular rotatable about a workpiece holder rotation axis. Additionally or alternatively, in a further development, the ECM module is mounted on the base body, in particular by an actuator, rotatable about a module rotation axis, which in one embodiment is inclined relative to the workpiece holder rotation axis, in particular enclosing an angle of between 80° and 100° with it. In one embodiment, this allows the module to process different areas of the workpiece sequentially and / or selectively, and can therefore be designed more compactly.

[0045] The workpiece holder is mounted on the base body for linear displacement, particularly vertically or horizontally, along a workpiece holder linear axis. Additionally, the module is mounted on the base body for linear displacement, particularly vertically or horizontally, along a module linear axis, particularly by means of an actuator. In one embodiment, the workpiece holder and / or module linear axis forms an angle of between 80° and 100° with the workpiece holder and / or module rotation axis.

[0046] As a result, in one embodiment, the module can precisely machine different areas of the workpiece one after the other and / or selectively and can be made more compact. In one embodiment, the workpiece holder has a chuck, in particular a zero-point fastening system, for releasably fastening the workpiece, which is or will be releasably connected to the base body. As a result, in one embodiment, the tool can advantageously first be fastened to the chuck, in particular a horizontally arranged chuck, and this chuck can then in turn be releasably fastened, in particular rotatably and / or linearly displaceably, to the base body or a workpiece holding flange, which in turn is mounted rotatably and / or linearly displaceably on the base body. In this way, asymmetries caused by gravity when fastening the workpiece can be advantageously reduced.

[0047] In addition to or as an alternative to the tool holder mounted on the base body for linear movement, the positioning device can comprise a robot with at least two, in particular at least six, actuated rotary joints for moving the workpiece holder relative to the module. This allows the workpiece to be positioned very variably and precisely relative to the module for processing.

[0048] In addition to or as an alternative to moving the workpiece holder relative to the module in the workstation, a robot can also be used or configured or provided to transfer or transport the workpiece from an upstream workstation and / or a buffer to the workstation, in particular to its workpiece holder, and / or to transfer or transport it after processing in the workstation to another downstream workstation and / or a buffer of the system. Accordingly, in one embodiment, the system has one or more buffers in order to temporarily store workpieces between processing in different workstations of the system, in particular those connected in series, and thus at least partially compensate for different cycle times, failures, tool changes, or the like.

[0049] In addition to or as an alternative to such a robot, the system can also have a crane, in particular a mobile or stationary one, with a lifting device in order to transfer or transport the workpiece from an upstream further workstation and / or a buffer to the workstation, in particular to its workpiece holder, and / or to transfer or transport it after processing in the workstation to a further downstream workstation and / or a buffer of the system. While a robot is advantageously particularly flexible, a crane in one embodiment can be more cost-effective and / or have a larger travel range and accordingly serve more workstations. In one embodiment, the crane can be moved between the workstation and at least one further workstation and / or at least one buffer, in particular on a ceiling or a scaffolding of the system.

[0050] In one embodiment, the system or workstation has a pivot bearing for pivoting the workpiece holder relative to the base, in particular into a vertical and / or horizontal position. Accordingly, in one embodiment, the workpiece holder, in particular a part of a base body described here, on which the workpiece holder or its workpiece holder flange is arranged, is pivotably articulated relative to the base, in particular into a vertical and / or horizontal position. This can improve the assembly and disassembly of, or fastening of, the workpiece to the workpiece holder and / or a chuck of the workpiece holder.

[0051] In one version, the system features a measuring device for measuring the workpiece. This allows its processing to be monitored and, in a further development, advantageously regulated, especially readjusted.

[0052] In one embodiment, the measuring device is an optical measuring device that can be configured to irradiate the workpiece with visible or invisible light and / or to receive visible or invisible light irradiated onto the workpiece. In a further development, the measuring device can comprise a light barrier, a laser, and / or a camera. In one embodiment, the measuring device is a tactile measuring device that can be configured to scan the workpiece.

[0053] In one embodiment, the measuring device measures the workpiece fastened to the workpiece holder of the workstation or is provided or configured to measure it. For this purpose, it can be mounted, in particular movably, on the workstation, in particular by a robot or on a base body described here. This allows the measurement to advantageously take place in situ. In another embodiment, the measuring device is located downstream of the workstation and accordingly measures the workpiece released from the workpiece holder of the workstation or is provided or configured to measure it. This allows the workstation to be made more compact and / or the measuring device can be used to measure the workpiece after processing in various workstations of the system.

[0054] According to the invention, the module for electrochemically machining a workpiece comprises a frame and an electrode arrangement with at least one electrode having a first surface working area and a second surface working area different therefrom and being mechanically connected to the frame, and a drive for moving this electrode, which drive is fastened to the frame.

[0055] According to one aspect, the module has a first operating mode in which only the first surface working area is subjected to voltage for electrochemical processing of the workpiece, and a second operating mode in which, in addition to or alternatively to the first surface working area, (also or only) the second surface working area is subjected to voltage for electrochemical processing of the workpiece.

[0056] Accordingly, according to one aspect of the present invention, in the first operating mode of such a module, only the first surface working area is subjected to voltage for electrochemical machining of the workpiece, selectively, in particular sequentially, and in the second operating mode, additionally or alternatively, the second surface working area is subjected to voltage for electrochemical machining of the workpiece.

[0057] By selectively applying voltage to different surface working areas of an electrode for the electrochemical machining of a workpiece, in one embodiment undercuts of the workpiece in particular can be machined, in particular manufactured, easily and / or precisely.

[0058] In addition or alternatively to such a first and second surface working area and mode, according to one aspect of a module described above and / or below, the electrode and the frame are mechanically connected to one another via a tool holder which is mechanically connected to the frame via two pivot arms of different lengths.

[0059] In one embodiment, this also allows undercuts in the workpiece to be machined, in particular manufactured, easily and / or precisely.

[0060] In one embodiment, the drive of a module described here has water cooling. Additionally or alternatively, in one embodiment, the drive of a module described here has an electric motor whose output shaft is designed as an eccentric shaft with a drive axis and a parallel, offset pivot axis, in particular an eccentric torque motor mentioned elsewhere. In a further development, the eccentric shaft is rotatably mounted in one or more ceramic bearings. This makes it possible to provide, in particular, a bearing that is resistant to the electrolyte for electrochemical processing. Additionally or alternatively, the eccentric shaft is screwed to a rotor of the electric motor, which is magnetically acted upon by a stator of the electric motor. This makes it possible to establish a particularly precise and / or reliable connection.

[0061] Further advantageous embodiments of the invention are set out in the subclaims.

[0062] In the following, preferred embodiments are described in more detail with reference to the partially schematic drawings to help understand the invention. In the drawings: Figures 1A, B: a module according to one embodiment; Figure 2: a module according to a further embodiment; Figure 3: a temporal movement sequence of a tool; Figure 4: another temporal movement sequence of a tool; Figure 5: a system not according to the invention with several work stations; Figure 6: a work station of the system in a side view (left in Fig. 6 ) and front view (right in Fig. 6 ); Figure 7: a work station of a system not according to the invention in a side view (top in Fig. 7 ) and top view (below in Fig. 7); Figure 8: a part of a module according to an embodiment; Figure 9: a part of a module according to an embodiment; and Figure 10: a drive of a module according to an embodiment.

[0063] In the Figures 1A and 1B1 shows an ECM module 1 according to a first embodiment, which machines a workpiece 2. The ECM module 1 comprises a frame 4, a drive 6 fastened to the frame 4, and a tool holder 8 to which a tool 10 is fastened. The drive 6 comprises a disk 12 which is fastened to a drive axis 14 and has a pivot axis 16. The disk 12 can also be merely a rod which is fastened to the drive axis 14 and accordingly has the pivot axis 16. Other shapes are conceivable. One end of a drive arm 18 is mounted on this pivot axis 16. The other end of the drive arm 18 is hinged to one end of the tool holder 8. The tool holder 8 is fastened laterally to the frame 4 via two pivot arms 20 and 22. The two pivot arms 20 and 22 form a so-called parallel rocker. The tool 10 (here an electrode) is fastened to the top of the other end of the tool holder 8.

[0064] Preferably, the first joint 24 between the tool holder 8 and the drive arm 18 is designed as a flexural joint. Preferably, the second joint 26 between the first pivot arm 20 and the tool holder 8 is designed as a flexural joint. Preferably, the third joint 28 between the second pivot arm 22 and the tool holder 8 is designed as a flexural joint. Preferably, the fourth joint 30 between the first pivot arm 20 and the frame 4 is designed as a flexural joint. Preferably, the fifth joint 32 between the second pivot arm 22 and the frame 4 is designed as a flexural joint.

[0065] In the Figures 1A and 1B The tranches (annular space) of blisks are preferably manufactured. A tranche refers to the machining of the spaces between the blades. Figures 1A and 1B differ only in that the distance between the electrode 10 and the workpiece 2 in Figure 1Ais greatest and the distance between the electrode 10 and the workpiece 1 in Figure 1B is the smallest.

[0066] The operation of module 1 is described below. The workpiece 2 (here a so-called blisk) is arranged above module 1. The blisk 2 comprises several blades 40, which are formed on a blade disk 42. This can also be a ring. The blade spaces 44 are arranged between the blades 40. In the Figure 1AThree blade gaps 44 and the outer surface of the blade disc 42 have already been electrochemically machined. In the following, it is described how the fourth blade gap 46 is machined using the module. For this purpose, the blade disc 42 was rotated counterclockwise about the rotation axis 48 until the fourth blade gap 46 is positioned exactly above the electrode 10. A vertical arrangement is shown here, but any desired arrangement can also be adopted, preferably horizontally. After positioning the gap 44 above the electrode 10, the drive 6 is switched on. Before commissioning the drive 6, the angle α 1 between the pivot axis 16 and the six o'clock position of the disc 12 in the Figure 1Aapproximately 125°. The drive 6 rotates the disk 12 counterclockwise until the angle α is approximately 180°. In this angular position of the disk 12, the maximum force can be transmitted from the drive to the tool 10. In order to realize small distances and achieve high machining frequencies, the angular difference is a maximum of 20°, i.e., the angle α is typically between 150° and 170°. When rotating the disk 12, the drive arm 18 is pressed against the tool holder 8, which in turn is pressed upwards in an elliptical path, so that the electrode 10 is machined into the shell surface of the blade disk 42 at a certain distance, as shown in Figure 1Bis shown. Electrolyte is continuously supplied (not shown here). This can be done via the electrode itself or via an additional supply. During machining of the shell surface, a voltage is applied between the blade disk 42 and the electrode 10. During material removal, the drive 6 can be switched off so that the electrode is in a certain fixed position. Or the drive 6 can continue to rotate during material removal, whereby the drive 6 can rotate both counterclockwise and clockwise. This moves the electrode 10 away from the blade disk 42. Fresh electrolyte can be supplied and the electrode 10 is placed back on the disk 42. This process is repeated until the corresponding target dimension has been machined into the shell surface of the blade disk 42.Then, the electrode 10 is retracted, and the blade disk is rotated further about the rotation axis 48. The not yet machined blade gaps 44 can then be machined one after the other.

[0067] In the Figure 2 An embodiment of an ECM module 50 according to a further embodiment is shown, which processes a blade 52 from two sides. This can be done simultaneously or staggered in time, as shown in the Figure 2 The device 50 is constructed mirror-symmetrically, with the mirror plane running vertically through the blade 52.

[0068] The left side of the ECM module 50 comprises a frame 54, a first drive 56 fastened to the frame 54, and a first tool holder 58 to which a first tool 60 is fastened. The first drive 56 comprises a first disk 62 which is fastened to a first drive axis 64 and has a first pivot axis 66. The first disk 62 can also be merely a rod which is fastened to the first drive axis 64 and accordingly has the first pivot axis 66. One end of a first drive arm 68 is mounted on this first pivot axis 66. The other end of the first drive arm 68 is hinged to one end of a first rocker 69. The first tool holder 58 is fastened to the frame 54 at the bottom via a first and a first second pivot arm 70 and 72. The two pivot arms 70 and 72 form a so-called parallel rocker. The first tool 60 (here an electrode) is attached to one end of the first tool holder 58 on the right.The first electrode 60 can, for example, have the complementary shape of the suction side of the blade 52. At the other end of the rocker 69, a first push arm 80 is pivoted at the top, which is pivoted at the left end of the first tool holder 58. Between the first push arm 80 and the first drive arm 68, the first end of a first support arm 82 is pivoted to the rocker 69, with the second end of the first support arm 82 being pivoted to the frame 54. Each individual pivot point can be designed as a flexure joint.

[0069] The right side of the ECM module 50 comprises the frame 54, a second drive 156 attached to the frame 54, and a second tool holder 158 to which a second tool 160 is attached. The second drive 156 comprises a second disk 162 attached to a second drive axis 164 and having a second pivot axis 166. The second disk 162 can also be merely a rod attached to the second drive axis 164 and correspondingly having the second pivot axis 166. One end of a second drive arm 168 is mounted on this second pivot axis 166. The other end of the second drive arm 168 is hinged to one end of a second rocker 169. The second tool holder 158 is attached to the frame 54 at the bottom via a second first and a second second pivot arm 170 and 172. The two second pivot arms 170 and 172 form a so-called parallel swing arm.The second tool 160 (here an electrode) is attached to one end of the second tool holder 158 on the left. The second electrode 160 can, for example, have the complementary shape of the pressure side of the blade 52. A second push arm 180 is pivoted to the other end of the second rocker 169 at the top, which is pivoted to the right end of the second tool holder 158. Between the second push arm 180 and the second drive arm 168, the first end of a second support arm 182 is pivoted to the second rocker 169, with the second end of the second support arm 182 being pivoted to the frame 54. Each individual pivot point can be designed as a flexure joint.

[0070] In the Figures 3 and 4 Graphs are shown that show how module 1 or 50 of the present invention operates.

[0071] In the Figure 3In the first square, the applied voltage over time is shown as a solid curve 201. Below that, in the fourth square, the position of the electrode over time is shown. For example, if the left (first) disk 62 is rotated counterclockwise at a constant angular velocity, the first electrode 60 experiences a sinusoidal position curve 200. The removal of material from the workpiece 52 takes place between the time periods t 4 and t 5, since during this time a voltage is applied between the first electrode 60 and the blade 52 (workpiece). It can be seen that the position of the electrode 60 changes constantly during the removal period t 4.5 (approx. 3 ms).

[0072] In the Figure 4In the first square, several applied voltages are plotted over time as solid curves 205 and 206. Below, in the fourth square, the positions of the electrodes are plotted over time. These are represented by the solid curves 210 and 220. Additionally, the angle α of the disk of a drive is plotted as a dotted line 230. In the module 50 of Figure 2 For example, the angle α 3 is formed on the first disc 62 between the three o'clock position and the actual position of the first pivot axis 66. On the left side of the module, the angle α 4 is formed on the second disc 162 between the nine o'clock position and the actual position of the second pivot axis 166.

[0073] The dashed curve 220 and the dash-dotted curve 230 belong together. The mode of operation will be explained in more detail using the second disk 162. The second drive 156 rotates the disk 162 counterclockwise from time 0 (angle α 3 = 164°) to time t 1 (angle α 3 = 152°). In doing so, the second drive arm 168 is displaced to the left, so that the second rocker 169 bends or rotates towards the second bearing arm 182. This causes the upper end of the second rocker 169 to pivot to the right. This removes the second tool holder 158, including the second electrode 160, from the blade 52. This allows fresh electrolyte to flow through the larger gap between the electrode 160 and the blade 52. Starting at time t 1 with an angle α 3 of 152°, the second drive 156 is reversed so that it now rotates clockwise up to an angle of 164°. This angle is reached at time t 3.This means that the second electrode is at the shortest distance from blade 52. From time t3 to time t6, the second electrode does not change its position because the second drive is switched off. During this time period, a square-wave voltage 206 can be applied, for example. Starting at time t6, the drive is switched on again, so that the second electrode 160 moves away from blade 52. The drive allows a different speed for approach and departure. The approach speed to the blade can be higher than the departure speed of blade 52, since no cavitation can occur during approach.

[0074] In contrast to the Figure 3The second drive 156 pivots back and forth between one angle and another. Here, one angle is 152° and the other angle is 164°. Other values ​​are conceivable. However, it has proven advantageous that the angle difference should not exceed 20°. In this exemplary embodiment, it is specifically 12°. This moves the second electrode 160 by a maximum of 500 µm.

[0075] The solid curves in the first 205 and fourth 210 quadrants belong together. In contrast to the broken curves, pulsed voltages 205 are also conceivable. The second electrode 160 only reaches its smallest distance at time t 4 . Pulsing allows the second electrode 160 to be retracted at a shorter time interval (t 7 - t 4 < t 6 - t 3 ), as this allows higher removal rates to be achieved. In this example, rinsing takes place between the time period t 0 and t 4 , and material is removed from the workpiece (e.g., a blade) between the time period t 4 and t 7 .

[0076] A module or process described here can be used particularly in the tranche production of blisks (or bling = bladed ring), especially as the final processing step. Tranche production refers to the machining of the spaces between the blades. Blisk stands for "blade-integrated disk," meaning that the blades are molded directly onto the disk. The module is easily scalable, meaning it can be easily designed for different dimensions.

[0077] Figure 5 shows a system not according to the invention with several workstations.

[0078] The system has an environmentally fixed base 300, an upstream workstation 301 for the electrochemical or generative production of a first rough contour of a blisk 51, two workstations 303, 304 connected in series downstream of this for ECM pre-machining and two workstations 305, 306 connected in series downstream of this for PECM final machining of the blisk for the electrochemical production of a second or final outer contour of the blisk 51 as well as a workstation 307 connected downstream of this with a measuring device 308 for the optical or tactile measurement of a blisk 51 released from a workpiece holder of the upstream workstations 301, 303-306.

[0079] In one embodiment, the system comprises a mobile or stationary crane (not shown) with a lifting device for transporting the blisk from one of the workstations 301, 303-307 or a buffer (not shown) to another of the workstations 301, 303-307 or a buffer (not shown). In one embodiment, the system additionally comprises one or more robots (not shown) for this purpose.

[0080] Figure 6 shows the workstation 306 of the system in a side view (left in Fig. 6 ) and front view (right in Fig. 6 ). One or more of the workstations 303-305 can be designed analogously.

[0081] The workstation 306 comprises a module 50 for electrochemical machining of the blisk 51, in particular its blades 52, which was described above with reference to Fig. 2 has been described in detail and is therefore only shown schematically here.

[0082] The work station 306 further comprises a workpiece holder for releasably securing the blisk 51 and a positioning device for moving this workpiece holder and the module 50 relative to each other.

[0083] The workpiece holder comprises a chuck 310, in particular a zero-point fastening system, for releasably fastening the blisk 51, which is releasably connected to a workpiece holder flange 311. This workpiece holder flange 311 is in turn, as shown in Fig. 6 indicated on the right by a movement arrow, can be rotated around a workpiece holder rotation axis by an actuator (not shown) and, as shown in Fig. 6Indicated on the left by a double-headed arrow, it is mounted on a part 312 of a base body by another actuator (not shown) for vertical linear displacement in a workpiece holder linear axis. The workpiece holder linear axis forms an angle of 90° with the workpiece holder rotation axis.

[0084] In addition, the module 50, as in Fig. 6 indicated on the left by a movement arrow, mounted on a base-fixed part 313 of the base body by an actuator (not shown) so that it can rotate about a module rotation axis. The module and workpiece holder rotation axis close in the Fig. 6 shown operating position an angle of 90°.

[0085] The positioning device accordingly comprises in particular the part 312 of the base body and the actuator for displacing the rotatably mounted workpiece holder 310, 311 thereon.

[0086] The work station 306 has a pivot bearing 314 for pivoting the part 312 of the base body and the workpiece holder 310, 311 mounted thereon relative to the base-fixed part 313 of the base body and thus also relative to the base 300, in particular into a vertical operating position and a horizontal position in which the fastening of the blisk or the chuck is facilitated.

[0087] Figure 7 shows a workstation of a system according to a further embodiment of the present invention in a side view (top in Fig. 7 ) and top view (below in Fig. 7 ), which in particular replace the provisions made above with reference to Fig. 6 described workstation 306 or one of the workstations 303 - 305 in the system of Fig. 5can be used. Corresponding features are identified by identical reference numerals, so that reference is made to the previous description and only differences are discussed below.

[0088] In the execution of the Fig. 7 is the module 50, as in Fig. 7 indicated above by a double arrow, mounted by an actuator (not shown) horizontally in a module linear axis on the base-fixed part 313 of the base body, which in the design of the Fig. 7 integral with the part 312 of the base body. In addition, the module 50, as shown in Fig. 7 indicated below by a double arrow, mounted on part 313 of the base body so that it can rotate about the module rotation axis by an actuator (not shown).

[0089] The workpiece holding flange 311 and the chuck 310 detachably connected thereto with the blisk 51 detachably attached thereto are, as shown in Fig. 7 indicated below by a movement arrow, mounted on the part 312 of the base body so as to be rotatable about a workpiece holder rotation axis by an actuator (not shown).

[0090] Here, too, the module and workpiece holder rotation axes form an angle of 90°. The module linear axis forms an angle of 90° with the workpiece holder rotation axis.

[0091] The positioning device here accordingly comprises in particular the part 313 of the base body as well as the actuator for moving the rotatably mounted module 50.

[0092] In the execution of the Fig. 6 Thus, the positioning device moves the rotatably mounted workpiece holder 310, 311 vertically relative to the rotatably mounted and stationary module 50, in the embodiment of the Fig. 6whereas the rotatably mounted module 50 is horizontal relative to the rotatably mounted and stationary workpiece holder 310, 311 on the base body 312, 313.

[0093] In addition to or as an alternative to the measuring device 308 of the downstream workstation 307, one or more of the workstations 301, 303 - 306 have an optical or tactile measuring device 315 for measuring the blisk 51 in situ. Like the measuring device 308, the measuring device 315 can be movably mounted on the respective workstation 307 or 306.

[0094] Figure 8 shows a modification of the above with reference to Fig. 2 module 50 according to an embodiment of the present invention. Fig. 8only a portion of module 50, insofar as this is relevant to explaining the modification. Corresponding features are identified by identical reference numerals, so reference is made to the previous description and only differences are discussed below.

[0095] The two mirror-image electrodes 60 and 160 (see also Fig. 2 ) each have first surface working areas 60a and 160a, respectively, and second surface working areas 60b and 160b, respectively, which are different therefrom. In the exemplary embodiment, the first surface working areas 60a, 160a are edge areas of the electrode 60 and 160, respectively, and the second surface working areas 60b, 160b are surface areas of the electrode 60 and 160, respectively.

[0096] Optionally, in particular sequentially, in a first operating mode of the module 50, only the first surface working areas 60a and / or 160a are subjected to voltage for electrochemical machining of the workpiece, and in a second operating mode, the second surface working areas 60b and 160b are additionally subjected to voltage. This allows, in particular, undercuts on inner and outer shrouds 52a, 52b of the blades 52 to be machined easily and / or precisely.

[0097] Figure 9 shows a modification of the above with reference to Fig. 2 8, respectively, according to an embodiment of the present invention. Fig. 9 again only a part of module 50, insofar as this is relevant to explaining the modification. Corresponding features are identified by identical reference numerals, so reference is made to the previous description and only differences are discussed below.

[0098] In the execution of the Fig. 9 The two swivel arms 70, 72 and 170, 172, via which the tool holders 58 and 158 are mechanically connected to the frame 54 (cf. Fig. 2 ), each have different lengths. As a result, the tool holders moved by the drives 56, 156 perform Fig. 9 In the initial position indicated by the dashed lines, in which the two pivot arms 70, 72 and 170, 172 are undeformed, in addition to the oscillation, a tilting movement relative to the frame. As shown in Fig. 9 As can be seen, undercuts on the cover bands of the blades 52 can also be machined in this way.

[0099] Figure 10 shows, again partially schematically, a drive of a module 1 or 50 already described above according to an embodiment of the present invention in the form of an eccentric torque motor.

[0100] This has a water cooling system 401. An output shaft is connected as an eccentric shaft 402 to the drive axis 14 (see Fig. 1 ) or 64 or 164 (cf. Fig. 2 ) and the swivel axis 16 (cf. Fig. 1 ) or 66 or 166 (cf. Fig. 2 ). The eccentric shaft is on the output side (left in Fig. 10 ) in ceramic fixed bearings 403 and away from the output (right in Fig. 10 ) is rotatably mounted in a ceramic bearing 404. The eccentric shaft 402 is screwed to a rotor 406, which is magnetically acted upon by a stator 405 of the motor, by means of screws 407. In addition, Fig. 10 a seal 408 of the eccentric shaft, a rotary encoder 409 and a power supply 410. List of reference symbols

[0101] 1 ECM module 2 workpiece 4 frame 6 drive 8 tool holder 10 Tool (electrode) 12 disc 14 drive axle 16 Swivel axis 18 drive arm 20 first swivel arm 22 second swivel arm 24 first joint 26 second joint 28 third joint 30 fourth joint 32 fifth joint 40 shovel 42 blade disc 44 Blade gap 46 fourth blade gap 48 axis of rotation 50 ECM module 52 shovel 54 frame 56 / 156 first drive / second drive 58 / 158 first tool holder / second tool holder 60 / 160 first tool / second tool 62 / 162 first disc / second disc 64 / 164 first drive axle / second drive axle 66 / 166 first swivel axis / second swivel axis 68 / 168 first drive arm / second drive arm 69 / 169 first seesaw / second rocker 70 / 170 first swivel arm / second swivel arm 72 / 172 first swivel arm / second swivel arm 80 / 180 first push arm / second push arm 82 / 182 first storage arm / second storage arm 200 sinusoidal electrode curve 201 rectangular voltage 205 pulsed voltage 206 rectangular voltage 210 second version trapezoidal position progression 220 first version trapezoidal position progression 230 Angle curve 51 Blisk 52a inner cover tape 52b outer cover tape 60a; 160a Edge area (first surface working area) 60b; 160b Surface area (second surface working area) 300 base 301; 303- 307 workstation 308, 315 Measuring instruments 310 Chuck (tool holder) 311 Tool holder flange (tool holder) 312, 313 Basic body part 314 swivel bearing 401 Water cooling 402 Eccentric shaft 403 Ceramic fixed bearing 404 Ceramic loose bearings 405 stator 406 rotor 407 screw 408 seal 409 rotary encoder 410 Power supply

Claims

1. System having a base (300) and at least one work station (306) which has an ECM module (50) for electrochemically machining a workpiece (51), wherein the ECM module comprises: a frame (4, 54); and an electrode arrangement having at least one electrode (60, 160) which comprises a first surface work region (60a, 160a) and a second surface work region (60b, 160b) and is mechanically connected to the frame (54), and a drive (6, 56, 156) for driving this electrode (60, 160), which drive is attached to the frame (54); a workpiece holder (310, 311) for detachably attaching the workpiece (2, 51, 52); and a positioning device for moving the workpiece holder (310, 311) and the module (1, 50) relative to one another, wherein the positioning device comprises a main body (312, 313), characterized in that both the, in particular rotatably mounted, workpiece holder (310, 311) and the rotatably mounted ECM module (50) are mounted on the main body (312, 313) so as to be movable linearly, in particular vertically or horizontally.

2. System having an ECM module according to claim 1, characterized in that the ECM module (50) has a first operating mode, in which only the first surface work region (60a, 160a) is supplied with voltage for electrochemically machining the workpiece (2, 51, 52), and a second operating mode, in which, additionally or alternatively, the second surface work region (60b, 160b) is supplied with voltage for electrochemically machining the workpiece (2, 51, 52).

3. System having an ECM module according to either claim 1 or claim 2, characterized in that the electrode (10, 60, 160) is mechanically connected to the frame (4, 54) via a tool holder (8, 58, 158) which is mechanically connected to the frame (4, 54) via two pivot arms (20, 22; 70, 72; 170, 172) of different lengths.

4. System having an ECM module (50) according to any of the preceding claims, characterized in that the drive has a water cooling apparatus (401).

5. System having an ECM module (50) according to any of the preceding claims, characterized in that the drive (6, 56, 156) comprises an electric motor, of which the output shaft is designed as an eccentric shaft (402) having a drive axis (14, 64, 164) and a pivot axis (16, 66, 166) offset in parallel and which is rotatably mounted in at least one ceramic bearing (403, 404) and / or screwed (407) to a rotor (406) which is acted upon magnetically.

6. System having an ECM module (50) according to any of the preceding claims, characterized in that the workpiece holder comprises a chuck (310) for detachably attaching the workpiece (51), which chuck is detachably connected to the main body (312).

7. System having an ECM module (50) according to any of the preceding claims, characterized in that the positioning device comprises a robot having at least two actuated rotary joints for moving the workpiece holder relative to the ECM module (50).

8. System having an ECM module (50) according to any of the preceding claims, characterized in that the positioning device comprises a crane having a lifting device and / or robot having at least two actuated rotary joints for transferring the workpiece (51) from a further work station (305) and / or a buffer and / or into a further work station (307) and / or a buffer of the system.

9. System having an ECM module (50) according to any of the preceding claims, characterized by a pivot bearing (314) for pivoting the workpiece holder (310, 311) relative to the base (300), in particular into a vertical and / or horizontal position.

10. System having an ECM module (50) according to any of the preceding claims, characterized by a measuring means (308, 315) for, in particular optically and / or tactilely, measuring the workpiece (51) which is in particular attached to the workpiece holder (310, 311).

11. System having an ECM module (50) according to any of the preceding claims, characterized by an upstream further work station (301-305) for, in particular electrochemically or generatively, producing a first outer contour of the workpiece (51) which comprises a machining allowance with respect to a second outer contour of the tool after machining in the downstream work station (306).

12. Method for electrochemically machining a workpiece (2, 51, 52) by means of a system according to any of the preceding claims, comprising the steps of: a. detachably attaching the workpiece (2, 51, 52) to the workpiece holder (310, 311); and b. moving the workpiece holder (310, 311) and / or the module (1, 50) relative to one another.

13. Method for electrochemically machining a workpiece (2, 51, 52) by means of a system according to any of the preceding claims, wherein, in the first operating mode of the ECM module (1, 50), only the first surface work region (60a, 160a) is supplied with voltage for electrochemically machining the workpiece (1, 51, 52) and, in the second operating mode of the ECM module (1, 50), additionally or alternatively, the second surface work region (60b, 160b) is supplied with voltage for electrochemically machining the workpiece (1, 51, 52).