DE102011082977B4 - Electrode for the electrochemical machining of a component - Google Patents

Abstract

Electrode (1) for the electrochemical machining of a component (2) with at least one electrode surface (6) inclined to an electrode feed direction (V), characterized in that the at least one inclined electrode surface (6) is reduced to an active electrode surface (7) in such a way in that the active electrode surface (7) corresponds to a countersink surface (8) of the electrode (1) projected in the direction of electrode advance (V) onto a plane (E) arranged perpendicular to the direction of advance of the electrode (V).

Description

The present invention relates to an electrode for the electrochemical machining of a component.

Although applicable to any application, the present invention and the underlying problem with respect to a blade of a turbomachine will be explained in more detail.

When electrochemical sinking with active electrode surfaces, which are employed parallel or at a small angle to the feed direction, creates a side gap, that is, a gap laterally between the electrode and the component, which can be influenced only insignificantly by the advancement of the electrode. In the case of electrode surfaces, which are arranged at a sinking angle inclined to the feed direction of the electrode, due to the change in the current density to the side in the side gap, a different material removal takes place on the component compared to the front gap. This removal is the greater, the greater the lowering angle deviates from the perpendicular to the feed direction of the electrode. The maximum of the gap is achieved parallel to the feed direction (complete side gap). Therefore, surfaces of the electrode, which are oriented parallel to the feed direction, usually provided with a full-surface insulation. In the case of inclined electrode surfaces, such an insulation is not possible since no material removal on the component can take place any longer in the provision of full-surface insulation in the region of the inclined electrode surfaces. In the internal practice of the Applicant is therefore trying to compensate by providing a larger electrode gap in areas inclined surfaces of the electrode additional material removal on the component. With the larger electrode gap a very different electrolyte exchange and an undesirable larger tolerance of the Abtragskontur is simultaneously connected. This is understandably to be avoided.

The DE 2153843 A discloses a method for accurately electrochemically machining workpieces of various shapes, the surfaces being inclined at a constant or continuously varying angle to the mutual feed direction of the tool and workpiece, which is different from the right angle, with at least one parameter changed at the surfaces of the workpiece becomes.

The DE 1 274 415 A discloses a hollow electrode for electrochemical metal working and a method for its production. The electrode consists of a stack of metallic plates, which are alternately separated by first and second spacers and wherein the channels formed between the plates are alternately connected at their opposite ends of the working surface with an inlet direction and a direction of contact for the electrolyte.

On this basis, it is an object of the present invention to provide an electrode for electrochemical machining of a component, in which the width of the side gap corresponds to the width of the end gap when the electrode is lowered into the component.

This object is achieved by an electrode having the features of claim 1.

According to the invention, an electrode is provided for the electrochemical machining of a component, wherein at least one inclined electrode surface is reduced to an active electrode surface in such a way that the active electrode surface essentially corresponds to a countersink surface of the electrode projected parallel to the electrode advancement direction.

The basic idea of the present invention is to reduce the area of at least one inclined electrode surface of the electrode. This ensures that the active electrode surface, which serves to remove the component, is reduced in such a way that the electrode can be lowered in the electrode feed direction into the component, wherein the side gap width substantially corresponds to the end gap width of the component. This makes it possible, when lowering the electrode into the component, to keep the side gap width essentially equal to the end gap width, whereby an end contour of the component can be manufactured both in the region of the side gap and in the region of the front gap with the highest tolerance requirements. Since in this procedure, a uniform gap over the entire sinking surface is generated, the replacement of the electrolyte flowing through the gap takes place uniformly and with the same flow rate. Dead water areas that lead to passivation are thus reliably avoided.

Advantageous embodiments and further developments emerge from the subclaims.

During the provision of the electrode, the at least one electrode surface inclined to the electrode advancing direction is reduced to the active electrode surface in such a way that the active electrode surface substantially corresponds to the projecting surface of the electrode projected in the electrode advancing direction onto a plane arranged perpendicular to the advancing direction. This advantageously allows a geometrically exact and reproducible definition of the target contour.

During the provision of the electrode, the at least one inclined electrode surface is reduced to the active electrode surface by providing an electrode insulation, in particular an electrode insulation comprising a plastic material, a ceramic material and / or any electrically insulating material. The electrode insulation is introduced in particular into the countersink surface of the electrode. As a result, a mechanically loadable electrode insulation is realized cost-effectively, whereby the costs for the application of the method are advantageously reduced.

When providing the electrode, the at least one inclined electrode surface, which is arranged in particular at a Elektrodensenkwinkel smaller than 90 ° relative to the electrode feed direction, only partially provided with the electrode insulation, wherein the respective Elektrodensenkwinkel associated active area ratio of the active electrode area a sine value of the respective Elektrodensenkwinkels equivalent. As a result, a material removal in the region of the inclined electrode surface is still possible despite the applied electrode insulation. The application in sections of the electrode insulation in the form of transversely or obliquely to the feed direction stripes or grid-shaped applied insulating reduces the active surface without affecting the geometry during lowering. A stripe width or diameter of the dots is preferably not greater than the minimum die gap during processing.

When providing the electrode, a straight electrode surface, which is arranged parallel to the electrode feed direction, is provided over the entire area with the electrode insulation. As a result, an undesirable enlargement of the side gap is reliably prevented, whereby the dimensional accuracy of the final contour of the manufactured component is improved in the application of the method.

In providing the electrode, the electrode insulation is provided on the inclined electrode surface in strip form transversely or obliquely to the electrode feed direction and / or as a point grid, wherein in particular widths of strips of electrode insulation or diameter of points of the dot grid of the electrode insulation are smaller than or equal to the gap width of the front gap. Preferably, the electrode insulation is applied as a support layer. The strip-like application of the electrode insulation can be produced quickly and cost-effectively, which reduces the costs associated with the use of the method. Alternatively, the electrode insulation, for example, be applied only punctiform.

When the component is provided, it is provided as a blade of a turbomachine, in particular a blade with a shroud or with two shrouds. As a result, turbine blades with two shrouds can be reliably lowered by means of the electrode in one operation without further work steps. As a result, the production of blades of a turbomachine is possible quickly and inexpensively.

For simultaneously forming a blade and the shroud or the shrouds of the blade, at least two, preferably up to six, electrodes, which are arranged in a star shape, fed to the target contour of the blade. As a result, a precise and rapid production of a blade by means of the method is possible.

The electrodes are all fed by a drive device all to the target contour of the blade, and reach their final position simultaneously. As a result, a simple control of the drive means for the electrodes is possible, whereby the costs are reduced in the application of the method.

The at least one inclined electrode surface is reduced to the active electrode surface by providing an electrode insulation, in particular an electrode insulation comprising a plastic material, a ceramic material and / or any electrically insulating material. The electrode insulation is preferably introduced into the countersink surface of the electrode. As a result, a mechanically loadable electrode insulation is realized.

According to a further preferred embodiment of the electrode, the at least one inclined electrode surface, which is arranged in particular at a Elektrodensenkwinkel smaller than 90 ° relative to the electrode feed direction, only partially provided with the electrode insulation, wherein the respective Elektrodensenkwinkel associated active area ratio of the active electrode area a sine value of corresponding Elektrodensenkwinkels corresponds. The application in sections of the electrode insulation in the form of transverse or oblique to the feed direction stripes or grid-shaped applied insulating reduces the active surface without affecting the geometry of the electrode. Preferably, a stripe width or diameter of the dots is not greater than the minimum die gap during processing.

According to a further preferred embodiment of the electrode is a straight electrode surface which is arranged in a Elektrodensenkwinkel parallel to the electrode feed direction, provided over the entire surface with the electrode insulation. This reliably prevents unwanted enlargement of the side gap during the application of the electrode, whereby the dimensional accuracy of the final contour of the manufactured component is improved in the application of the electrode.

According to a further preferred development of the electrode, the electrode insulation is provided on the at least one inclined electrode surface in strip form transversely or obliquely to the electrode feed direction and / or as a point grid, in particular widths of strips of electrode insulation or diameter of points of the electrode insulation is less than or equal to the gap width of the end gap are. The strip and / or point application of the electrode insulation can be produced quickly and inexpensively, which reduces the costs involved in the production of the electrode.

The invention will be explained in more detail below with reference to a preferred embodiment with reference to the accompanying figures of the drawing.

From the figures show

1 a partial sectional view of an electrode according to a preferred embodiment of the present invention;

2 a partial sectional view of an electrode according to another preferred embodiment of the present invention; and

3 a method using the electrode according to the invention

In the figures of the drawing are identical and functionally identical elements and features - unless otherwise stated - provided with the same reference numerals.

The 1 illustrates a preferred embodiment of an electrode 1 for the electrochemical machining of a component 2 and a device for electrochemically machining the component 2 , The component 2 , in particular an end or target contour of the component 2 is preferably designed as a blade of a turbomachine, in particular as a blade with a shroud or with two shrouds. The electrode 1 is preferably as a so-called sinking electrode 1 formed and in particular has a metallic or any electrically conductive material. The electrode 1 has an electrode feed direction V, in which they under material removal on the component 2 into the component 2 is lowerable.

The electrode 1 is preferably formed as a three-dimensional solid. Furthermore, the electrode 1 , as in 1 illustrated, viewed in a direction perpendicular to the electrode feed direction V, have an almost arbitrary cross-section, which is preferably formed without undercuts. A back surface of the electrode 1 is preferably the component 2 turned away and can be a mounting flange 4 for mounting the electrode 1 have at a traversing device of the device. An end face 13 the electrode 1 is preferably the component 2 facing. The electrode 1 in particular has at least one electrode surface inclined to the electrode feed direction V. 6 on. The at least one inclined electrode surface 6 can in accordance with the sectional view 1 be oriented in a Elektrodensenkwinkel α to the electrode feed direction V. Furthermore, the inclined electrode surface 6 be designed as a rounding. In particular, the electrode 1 a variety of inclined electrode surfaces 6 with different or the same Elektrodensenkwinkeln α ₁ , α ₂ , ... α _n have. In the embodiment of the electrode 1 according to 1 this has, for example, two differing electrode cone angles α ₁ and α ₂ . The inclined electrode surface 6 can have almost any three-dimensional geometry, wherein the inclined electrode surface 6 is characterized in particular in that these in the sectional view according to 1 not parallel to the electrode feed direction V extends. In particular, the electrode depression angle α is the inclined electrode surface 6 not equal to 90 °. Preferably, the electrode cone angle α is formed smaller than 90 ° relative to the electrode feed direction V. The electrode 1 can also have a straight electrode surface 10 exhibit. The straight electrode surface 10 runs according to the sectional view of the electrode 1 to 1 essentially parallel to the electrode feed direction V, that is, the electrode cone angle α of the straight electrode surface corresponds approximately to 0 °. An electrode angle α of 0 ° is to be understood as meaning a certain angular range, which may be dependent on the component material, the process conditions and the electrode material.

The inclined electrode surface 6 is preferably on an active electrode surface 7 reduces that active electrode area 7 essentially a parallel to the electrode feed direction V on a perpendicular to the electrode feed direction V arranged plane E projected lowering surface 8th the electrode 1 equivalent. The active electrode area 7 indicates besides a proportion of the inclined electrode surface 6 for example, the face 13 the electrode 1 on. The sinking area 8th the electrode 1 corresponds approximately to the light shade, the electrode 1 generated on the perpendicular to the electrode feed direction V arranged plane E, when the electrode 1 in the direction of the face 13 in Feed direction V is irradiated with a parallel light beam. The sinking area 8th may be any two-dimensional shape such as a round, square, elliptical or any shape.

The inclined electrode surface 6 in particular, by the provision of an electrode insulation 9 on the active electrode surface 7 reduced. The electrode insulation 9 may be formed in particular in the form of an electrically insulating plastic material, electrically insulating ceramic material and / or any electrically insulating material. The inclined electrode surface 6 is preferably only partially with the electrode insulation 9 Mistake. Furthermore, the straight electrode surface 10 , which is arranged substantially parallel to the electrode feed direction V, the entire surface with the electrode insulation 9 Mistake. In particular, faces of the electrode 1 , which are arranged approximately perpendicular to the electrode feed direction V, such as the end face 13 , the electrode insulation 9 not up. In particular, the active electrode surface has 7 such uninsulated areas of the electrode 1 , such as the face 13 , the electrode 1 on. At the inclined electrode surface 6 is the electrode insulation 9 in particular strip-shaped transversely and / or obliquely to the electrode feed direction V arranged. In particular, the inclined electrode surface 6 with a plurality of transversely and / or obliquely to the electrode feed direction V extending recesses 11 , in particular grooves 11 , provided in which the electrode insulation 9 is introduced. The grooves 11 may in particular have different groove widths but preferably do not exceed a width of a minimum sinking gap. In particular, the electrode insulation 9 even without the provision of the recesses 11 on the inclined electrode surface 6 or the straight electrode surface 10 be arranged. For example, the electrode insulation 9 as an electrically insulating support layer by means of a chemical and / or physical deposition process on the electrode 1 attached and / or generated by reactive oxidation on the surface. Alternatively, the electrode insulation 9 For example, be applied only punctiform.

The 2 illustrates another preferred embodiment of the electrode 1 , In the following, only differences to the embodiment of the electrode according to the 1 explained. In the embodiment of the electrode 1 according to 2 is the inclined electrode surface 6 in particular designed as a rounded surface. The inclined electrode surface 6 is with the grooves 11 provided in the electrode insulation 9 is introduced. By providing the electrode insulation 9 is the inclined electrode surface 6 such on the active electrode surface 7 reduces that active electrode area 7 essentially the lowering surface projected parallel to the electrode feed direction V. 8th the electrode 1 equivalent.

A device for electrochemical machining of the component 2 preferably has an electrode 1 according to the 1 or 2 on. Furthermore, the device has the traversing device for moving the electrode 1 in the electrode advancing direction V and an electrolyte supply device for supplying an electrolyte. Still further, the device has a power supply device 12 on which both with the component 2 as well as with the electrode 1 by means of connecting elements 19 . 20 , especially power lines 19 . 20 , is electrically operatively connected. The component 2 is preferably as an anode and the electrode 1 is preferably connected as a cathode.

The 3 illustrates a preferred embodiment of a method for electrochemically machining the component 2 with an electrode 1 according to the 1 or 2 , In an initial method step S1, the component becomes 2 provided. The component 2 can be provided in particular as a blade of a turbomachine, in particular as a blade with a shroud or with two shrouds.

In a further method step S2, the electrode 1 provided. In providing the electrode 1 becomes the at least one electrode surface inclined to the electrode advancing direction V. 6 such on the active electrode surface 7 reduces that active electrode area 7 essentially the lowering surface projected parallel to the electrode feed direction V. 8th the electrode 1 equivalent. The sinking area 8th the electrode 1 is preferably projected onto the plane E, which is arranged perpendicular to the electrode advancing direction V. In particular, in method step S2, the electrode is provided 1 the at least one inclined electrode surface 6 or a plurality of inclined electrode surfaces 6 by providing the electrode insulation 9 on the active electrode surface 7 reduced. The electrode insulation 9 becomes when providing the electrode 1 preferably only in sections on the inclined electrode surface 6 intended. In particular, the inclined electrode surface 6 is arranged at a Elektrodensenkwinkel α smaller than 90 ° relative to the electrode feed direction V. Further, the straight electrode surface becomes 10 the electrode 1 , which is arranged substantially parallel to the electrode feed direction V, the entire surface with the electrode insulation 9 Mistake. At the inclined electrode surface 6 In particular, the recesses provided transversely and / or obliquely to the direction of electrode advance V are provided 11 , for example in the form of grooves 11 , which introduces the electrode insulation 9 take up. Alternatively or additionally, the electrode insulation 9 applied by a chemical or physical deposition process.

In a further method step S3, the electrode 1 by means of the traversing device of the device during the electrochemical machining of the component 2 in the electrode feed direction V in the component 2 lowered. It is only of the component 2 Material removed while the electrode 1 Process-related not removed. A resulting component contour preferably corresponds to a contour of the electrode 1 , While lowering the electrode 1 into the component 2 is by means of the power supply device 12 between the electrode 1 and the component 2 a voltage is applied, the component 2 as the anode and the electrode 1 is switched as the cathode. When lowering the electrode 1 into the component 2 is between the frontal area 13 the electrode 1 and the component 2 a frontal cleft 14 formed with a front gap width a. Furthermore, at the same time becomes laterally between the electrode 1 and the component 2 that is between that of the straight electrode surface 10 and the inclined electrode surface 6 formed contour of the electrode 1 and the component 2 , a side gap 15 formed with a side gap width b. The electrode 1 is preferably in the component 2 lowered that the side gap width b of the side gap 15 essentially the front gap width a of the end gap 14 equivalent. This is possible in particular, since the reduction of the inclined electrode surface 6 on the active electrode surface 7 on the inclined electrode surface 6 preferably an identical component removal as on the end face 13 the electrode 1 he follows. The component removal is by the adaptation of the inclined electrode surface 6 on the active electrode surface 7 from the inclination of the inclined electrode surface 6 independently. The side gap 15 is thereby reduced as a function of the Elektrodensenkwinkels α so far that the front and side gap 14 . 15 assume almost equal widths a, b. As a result, the final contour of the component 2 without the provision of one compared to the frontal gap 14 widened side gap 15 producible, whereby the final contour of the component 2 can be created with high manufacturing accuracy. Preferably, during the lowering of the electrode 1 into the component 2 by means of an electrolyte supply device of the device, an electrolyte from the side gap 15 supplied. The electrolyte preferably flows in the end gap 14 and the side gap 15 as in the 1 and 2 by means of the arrows 16 indicated. The electrolyte serves as a contact medium for the electrochemical reaction and for the removal of removed material of the component 2 , The supply of the electrolyte in a uniformly thick gap allows reliable removal of the removed by the electrochemical process material of the component from the side gap 15 and the frontal cleft 14 , whereby the achieved surface quality and the geometry of the component 2 when lowering is improved.

In a further development of the method according to 3 in particular at least two, preferably up to six electrodes 1 arranged in a star shape and on a target contour of the component 2 , in particular a blade of a turbomachine, fed in, the electrodes 1 reach their respective end positions at the same time.

By means of the electrode 1 according to the 1 or 2 and / or the method according to 3 becomes the side gap 15 depending on the Elektrodensenkwinkels α so far reduced that the face gap 14 and the side gap 15 assume nearly the same values of the end gap width a and the side gap width b. As a result, the lowering of side surfaces with approximately the same precision as in the face gap 14 possible. Turbine blades with two shrouds can be lowered in one operation without further rework. The electrode insulation 9 is preferably strip-shaped and / or as a dot matrix on the at least one inclined electrode surface 6 arranged, wherein a width of the strips or a diameter of the points does not exceed the minimum gap width and thus in the lowering of the electrode 1 into the component 2 a disturbance of the surface of the component 2 through the electrode insulation 9 is prevented. This is accomplished by having the electric field required for the sinking process not only perpendicular to a surface of the electrode 1 spread, whereby an overlap of the electric fields occurs during lowering. A step formation on the component 2 is thereby reliably prevented. With the method according to 3 For example, a gas passage of a bucket can be lowered completely with close tolerance. Blades of an engine with one or two shrouds without undercuts can be lowered with this method in one operation with close tolerance.

LIST OF REFERENCE NUMBERS

1

electrode

2

component

4

mounting flange

6

inclined electrode surface

7

active electrode surface

8th

projected in the feed direction Senkfläche

9

electrode insulation

10

straight electrode surface

11

recess

12

Power supply means

13

face

14

end gap

15

side gap

16

electrolyte flow

19

Power line (+)

20

Power line (-)

a

End gap width

b

Side gap width

e

level

V

Electrode feed direction

α

Elektrodensenkwinkel

Claims (5)

Electrode ( 1 ) for the electrochemical machining of a component ( 2 ) with at least one electrode surface inclined to an electrode feed direction (V) ( 6 ), characterized in that the at least one inclined electrode surface ( 6 ) on an active electrode surface ( 7 ) is reduced, that the active electrode surface ( 7 ) a projecting in the electrode feed direction (V) on a perpendicular to the electrode feed direction (V) plane (E) ( 8th ) of the electrode ( 1 ) corresponds. An electrode according to claim 1, characterized in that the at least one inclined electrode surface ( 6 ) by means of an electrode insulation ( 9 ), which comprises any electrically conductive material, in particular a plastic material and / or a ceramic material, on the active electrode surface ( 7 ) is reduced. Electrode according to Claim 2, characterized in that the at least one inclined electrode surface ( 6 ), which is arranged at an electrode deflection angle (α ₁ , α ₂ ) of less than 90 ° relative to the electrode feed direction (V), in sections with the electrode insulation ( 9 ), wherein one of the respective Elektrodensenkwinkel (α ₁ , α ₂ ) associated active area fraction of the active electrode surface ( 6 ) corresponds to a sine value of the respective electrode steering angle (α ₁ , α ₂ ). Electrode according to Claim 2 or 3, characterized in that a straight electrode surface ( 10 ), which is arranged parallel to the electrode feed direction (V), the entire surface with the electrode insulation ( 9 ) is provided. Electrode according to Claim 3, characterized in that the electrode insulation ( 9 ) on the at least one inclined electrode surface ( 6 ) is provided strip-shaped transversely or obliquely to the electrode feed direction (V) and / or as a point grid.

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