KR20190020737A - Electrolytic polishing method and apparatus and cathode manufacturing method - Google Patents

Abstract

Electrolytic polishing method and apparatus and cathode manufacturing method
A method and apparatus for electrolytically polishing a recessed inner surface (22) of a metal workpiece (14), particularly a three dimensional printed workpiece (14), wherein the cathode (30) is introduced into the recess and has a slow diffusion rate There is provided an apparatus for polishing an inner surface of a recess using an electrolyte (12).

Description

Electrolytic polishing method and apparatus and cathode manufacturing method

The present invention relates to a method and apparatus for electrolytically polishing a recessed inner surface of a workpiece made of a metal, especially a workpiece produced by a production method. The present invention also relates to a method of manufacturing a cathode.

Methods of electrolytic treatment of workpieces are known. The workpiece is placed in an electrolytic cell and connected to the anode. As a tool, the cathode should be placed as close as possible to the workpiece, and the shape of the upper side of the cathode facing the workpiece should correspond as close as possible to the surface of the workpiece to be produced later. In addition, in order to make the dissolution of the material on the workpiece fast and uniform, the so-called working gap between the workpiece and the cathode must be small and uniform.

Generative manufacturing methods, especially those produced by printing in three dimensions, have recesses that are not capable of mechanical micro-machining because the profile of these recesses is not linear. In addition, the cross-section of the recesses may be so small that the mechanical polishing method can not be performed or at least can not be performed economically.

It is therefore an object of the present invention to obviate such disadvantages.

The present invention provides a method for polishing an electrolyte anode of a recessed inner surface in a workpiece made of a metal, particularly a workpiece produced by a production method, which is specified in the following steps.

(A) immersing the workpiece in an electrolyte comprising an alcohol having a minimum weight ratio of 20 to 70%, especially 40 to 70%, per liter of salt, water and electrolyte;

(B) connecting the workpiece to a positive pole so that the workpiece forms an anode;

(C) providing at least one cathode in the electrolyte and the recess;

(D) providing relative movement between the electrolyte and the workpiece; And

(E) applying a voltage between the anode and the at least one cathode.

The method according to the invention and the device according to the invention will be further illustrated below, but are not limited to deburring of the workpiece. Rather, the present invention relates to surface polishing.

The idea underlying the present invention is to process or process rough workpieces in the recesses by electrolytic polishing as a whole and the interaction between process parameters, electrolyte properties and tool design is such that when a direct current is applied, Lt; RTI ID = 0.0 > a < / RTI > viscous layer is formed on the anode surface.

The following factors are provided separately and together for this layer. In other words,

· Selection of electrolyte components distinguished by viscosity higher than water viscosity. Viscosity is a crucial factor for reducing the drift rate of ions;

Maintaining the process temperature relatively low, especially 7 - 15 ° C;

· Keep water activity / relative humidity (cow "aw value") as low as possible. The aw value ranges from 25 to 70%, ideally from 27 to 50%;

Selecting appropriate salts to produce the appropriate conductivity of the electrolyte; And / or

· Constant flow conditions in the gap for uniform layer build-up on the anode surface and exchange of charge carriers.

By selecting a suitable DC parameter, the structure and thickness of the layer can be controlled.

Current pulses with the parameters specified on the next page have been found useful here.

Benefits of the invention:

· Large area parts can be machined using relatively small currents.

Large gaps can be used.

• As the drift velocity decreases, the sensitivity of the anode surface to fluctuations in the current density is greatly reduced, so that the tool geometry roughly conforms to the shape of the workpiece.

The ion migration rate during operation is 0.1 ~ 5m / sec. This is in contrast to what is actually provided for the internal treatment of the recess for surface treatment because the electrolytes providing a high diffusion rate because of the already poor accessibility of the electrolytes and cathodes to the recesses or recesses, At first glance, it is more suitable for large area processing. However, the present invention takes the opposite path. The electrolyte makes it possible to achieve a larger gap width and as a result the cathode must follow the path of the recess less since the gap width is a distance that simultaneously affects the geometric tolerance of the cathode. Also, as the diffusion rate is slow, the slower the processing rate, the more a compensation effect is provided in the gap with respect to the removed peak. This means that this effect can operate at significantly lower current densities. This compensation effect can be explained by the fact that the charge at the so-called peaks of the workpiece surface is stronger than the flat surface, which is why the ions are exchanged first. Special electrolyte solutions cause semiconductor-like behavior in the electrolyte. That is, while the exposed surface on the part is preferentially removed, the flat surface or more generally the non-peaked surface is protected by the electrolyte properties and attacked later. Removal is heavily influenced by the peak. The speed of the ion itself is affected not only by the composition and viscosity of the electrolyte, but also by the temperature of the electrolyte or the relative movement between the electrolyte and the workpiece. This compensation effect can be explained in some detail by the fact that the peak is exposed to an enhanced electric field and the salt in the electrolyte releases the charge in a manner that induces oxygen formation and thus leads to oxidation of the metal surface. The resulting metal oxide layer is at least a temporary protective layer for the electrolyte.

A preferred embodiment of the present invention provides that the process is used in a production method of metal (additive production). These manufacturing methods include 3D printing processes, including ALM, DMLS and SLM processes. Here, the idea is to turn the disadvantage of the additive manufacturing product into an advantage of the polishing process. In particular, in order to economically manufacture an additive manufacturing product, i.e., a 3D printing product, in the aviation industry, a manufacturing process, that is, a printing process, must be performed as soon as possible. That is, large particle sizes (eg, laser sintering) must be produced. However, this large particle size makes the surface quality unacceptable and can be regarded as a peak. The grains are smoothly polished on the surface by the method according to the invention. An advantage of the electrolyte used in the present invention is that the electrolyte preferentially removes protrusions of the grain.

According to the present invention, the alcohol used is preferably a polyhydric alcohol.

An ammonium salt or an alkali salt (for example, an alkali sulfamate or sodium sulfamate) may be used as a salt. For example, the salt content is at least 50 g / l of the electrolyte, especially less than 150 g / l and less than 400 g / l.

Glycol or other high viscosity media can be used, for example, as an alcohol that can absorb the salt directly or form a single phase liquid that can be mixed with water.

The content of water relative to the electrolyte can optionally be up to 20%.

The temperature of the electrolyte during the treatment should preferably be in the range of 0 ° C to 30 ° C, especially 5 ° C to 20 ° C, preferably 7 ° C to 15 ° C.

The pH value of the electrolyte should be at most 6.8, especially 5.0 to 6.8.

It has been found that the electrolyte should have a so-called conductance of 10 to 40 mS at 20 占 폚.

The relative movement between the electrolyte and the workpiece can be achieved by moving the workpiece in the electrolyte or by moving the electrolyte, i.e., by pumping the electrolyte to create a flow along the surface of the workpiece. Of course, it is also possible to move both electrolytes and workpieces.

In order to achieve a uniform movement of the electrolyte on the workpiece surface, the workpiece is preferably moved along a guide.

The workpiece is made of a metal material, for example a light metal such as nickel or chromium alloy or aluminum. These metals have been found to be the preferred metal for use in the process according to the invention and the device according to the invention.

The cathode, which should not be in contact with the anode, must be connected to the cathode of the power source by an electric line, in particular a flexible cable, and inserted into the recess in the workpiece for the inner surface treatment of the recess. The cathode is located near another cathode connected to the power source and is not a so-called fake cathode connected to the power source only through the electrolyte, which is a cathode directly connected to the power source.

This cathode allows removal to be achieved, for example, not only at the tip of the cathode but rather over a large area of the cathode.

In particular, the cathode can be formed to have flexibility and can laterally bend so that the cathode can abrade the non-linear recess to follow the profile of the recess.

At least one electrically insulating spacer connected to the cathode may protrude laterally from the cathode. This spacer prevents contact with the workpiece. In particular, the spacer may be used as a guide. This means that the present invention provides that the spacer is in contact with the workpiece. A portion of the cathode that is not electrically insulated is used for removal. In particular, when a cathode is inserted into a deep opening with a curved profile in a workpiece made of a flexible and productive manufacturing method (e.g., a 3D printing component), the cathode will follow the profile of curvature despite the curvature , Is bent and still does not contact the inner surface of the recess.

In a particularly advantageous variant of the cathode used, it is provided that the cathode is composed of a kind of circular brush with its spacers. The insulation spacer projects the filament. The cathodes may be formed of one or more twisted wires that secure the filaments between them.

Another variant of the invention is that the cathode is elongated, in particular a rotating body, having a spiral and an electrolyte-carrying groove on its outer surface. Such a cathode has, for example, a drill shape with a flute serving to carry the electrolyte. The grooves extend to the core formed by the electrolyte. The side boundary of the groove can be defined entirely by, for example, an insulator. This design has several advantages. By rotating the cathode, the portion of the cathode located at the base of the groove is always opposite to the different portions of the workpiece inner wall to uniformly remove the material. This allows particularly uniform polishing to be performed. Also, by inducing flow through the grooves or by rotating the cathode, the electrolyte is carried as in a screw type pump.

In the case of a clogged hole, it may be considered to provide a suction hole or rather a discharge hole, for example at the center of this cathode tool. The electrolyte is fed through the spiral groove and discharged through the central opening.

In particular, when the spacer temporarily covers the interior of the recess, it is advantageous to move the workpiece, especially in the axial and / or circumferential direction, after the first polishing step to expose the space where the space was previously present. A subsequent polishing step may be carried out in this region which is situated opposite to the polishing surface (contact or noncontact) and is performed to polish a portion of the inner surface of the recess previously provided as a support region.

A preferred embodiment of the present invention provides for simultaneous polishing of the inner surface by applying a voltage to the outer surface of the workpiece. This significantly reduces processing time.

As already mentioned above, in order to achieve relative movement between the electrolyte and the workpiece, the electrolyte may be pumped past the workpiece and / or the workpiece is moved in the container containing the electrolyte, in particular along the aforementioned linear guide. At least one of the cathodes may have a surface that is opposed and profiled to the workpiece, i. E., A flat non-cylindrical surface. This profiling can improve the removal process, especially if the profiling is similar to the subsequent appearance of the workpiece surface.

In this regard, the cathode has a side facing the workpiece, and it may be advantageous to have a constant gap on the side of the workpiece prior to processing of the workpiece. Here, the constant gap may exist before the workpiece is processed, or the reference for determining the gap and the side surface of the cathode are finished workpieces. It should be emphasized, however, that a very uniform gap between the surface of the workpiece and the opposite surface of the cathode, which has hitherto been conventional, is not essential to the present invention. The gap can be unevenly extended, which reduces the effort required to create the shape of the cathode. Also, the same cathode can be used for similar surface shapes. Due to process characteristics, the rough surface of the cathode is not related to the surface quality achieved for the workpiece.

It is particularly advantageous when the cathodes and / or support structures forming the anode are simultaneously produced or simultaneously printed simultaneously or offset with the production process, i.e., the 3D printing process. This allows the precise shape of the cathode to be positioned close to the surface to be treated without further effort of a particular shape. The support structure ensures that no spots appear on the workpiece surface after the electrolytic treatment that may have occurred before the anode is applied. It is particularly preferred that a plurality of workpieces are seated on the support structure and subsequently subjected to electrolytic treatment. This results in greater stability during processing of the workpiece to be treated, and handling is greatly simplified.

The support structure is preferably separated from the workpiece after the electrolytic treatment of the recesses after the entire workpiece is treated. This separation process may be performed mechanically or by spark erosion.

For production production, metal particles having a diameter of 20 mu m to 60 mu m are used, from which a workpiece is constituted.

In general, during the electrolytic treatment, the workpiece, in particular a plurality of workpieces, can be seated on a support plate which forms an angle. The support plate may be, for example, the above-described support structure that is generatively produced with the workpiece.

The cathode for external processing of the workpiece, i. E. The cathode for processing the workpiece outside the recess, is fixed to the support plate, for example by means of an electrically insulated mounting means, in particular by plug connection means. This cathode or these cathodes can also be produced producibly.

For processing of the recesses, the cathode can be inserted into the recess and the electrolyte can be pumped into the gap between the cathode and the inner surface of the workpiece opposite it. An electrolyte conduit is provided for improving the treatment, especially for precisely predetermined treatment of the recess, for example, by returning to the recess and introducing the electrolyte into the recess. This can also be influenced through the duct duct inside the cathode.

The movement of the cathode in the recess can be performed by a motor or manually. In particular, the reciprocating movement of the cathode can also be realized by a motor drive apparatus.

As described above, the present invention relates to an inner surface of a recess of a workpiece made of metal, particularly an electrolytic cathode polishing apparatus for a 3D printed workpiece. The apparatus comprises a container filled with an electrolyte containing an alcohol having a salt, water and a minimum weight ratio of 20% to 70%, preferably 40% to 70%, a holding device for the workpiece, A cathode which has an electrical insulator in its part and which is connected to the power supply by means of a cable, on the one hand an electrolyte and / or cathode present in the aperture, on the other hand a drive device provided for producing a relative movement between the workpieces.

The present invention also relates to a process for the production of cathodes for the electrolytic treatment of workpieces, especially productions which are produced. The cathode has a side facing the workpiece to be treated, in particular for carrying out the process according to the invention. However, the cathode may be provided for external processing of the workpiece. The external geometry of the cathode is identified at least in the area of the side facing the workpiece using the simulation program. In the simulation program, the electric field and / or the magnetic field existing between the cathode and the workpiece to be produced during the electrolytic treatment are determined. The external geometry of the cathode of the aforementioned side is identified by considering the constant current density between the side and the cathode. The cathodes are fabricated by a production process based on the determined external geometry. This method considers that there is an increased charge density in the region of the edges in a subsequent electrolytic treatment process, which can be compensated by the appropriate geometry of the cathode. For example, in these areas, a larger gap for the workpiece can be provided.

All of the features and advantages described above in connection with the method according to the invention also apply to the device according to the invention.

Further, the apparatus according to the present invention is not limited to deburring and serves to polish the inner surface of the recess.

In particular, a flexible cathode is provided and, in part, is provided with an electrical insulator which protrudes outwardly in the form of a shell, particularly as a spacer, in the form of a shell which surrounds the core, which comprises a corrugated bristle or helical groove and forms a cathode.

In addition to the cathode introduced into the recess, at least one external cathode for polishing the external surface of the workpiece may be provided, which is connected to the same power source as the internal cathode and simultaneously polishes the external surface.

The electrolyte used is the electrolyte previously used in connection with the process according to the invention.

A number of tapers, i.e., 3D printed products, for polishing the recesses of the products produced by the method of the present invention, show that the method according to the invention and the apparatus according to the invention have a surface roughness RZ 60 to RZ 3 -4 To-date.

In addition, the method according to the present invention is also applicable to articles produced by a production method, such as 3D printing products, that is, to a product (e.g. The method according to the invention and the device according to the invention eliminate such supporting structures, which are not possible to use mechanical tools because accessibility is not given.

The apparatus according to the invention and the method according to the invention are characterized in that they are applied in the range of 10V to 40V, ideally 15V to 30V, and 0.0003A / mm2 to 0.01A / mm2, preferably 0.003A / mm2 to 0.01A / Use the operating range for current more specifically.

The size of the gap is 1.0 mm to 100 mm.

In particular, a pulse method is applied that operates on local overheating, pitting, irregular metal melting, soot and flux lines. The optimum pulse-pause ratio is from 4: 1 to 1: 4, preferably 2: 1, in particular, depending on the material of the workpiece and the electrolyte.

It has been found that the halogen content in the electrolyte improves its properties. The total amount of halogen is in the range of 0 g to 100 g per liter of electrolyte.

A replacement holder for fixing the cathode may be provided, which is provided with a drive for moving the power and / or electrolyte connection and / or the cathode.

Other features and advantages of the present invention will become apparent from the following description and the accompanying drawings in which reference is made.

According to the present invention, a large-area part can be processed using a relatively small current, a large gap can be used, and the sensitivity to fluctuations in the current density of the anode surface is greatly reduced when the drift speed is reduced. Approximates the shape of the workpiece precisely.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view schematically showing an apparatus according to the invention for carrying out the method according to the invention.
2 to 4 are views showing another embodiment of the cathode used in the apparatus according to the present invention and the method according to the present invention.
Figure 5 is a schematic side view of another embodiment of the device according to the invention.

Figure 1 shows an apparatus for electrolytic anodic polishing, the apparatus having a container 10 filled with an electrolyte 12. The workpiece 14 can be completely immersed in the electrolyte 12 by the holding device 16 and reciprocated along the linear guide 18 by the motor 20. The workpiece 14 has a recess in the form of an arcuate curved hole. The recess is formed with an inner surface (22).

The workpiece 14 is connected to the power source 26 by a cable 24 and acts as an anode. One or more cathodes (28, 30) are also connected to the power source (26) by cables (32). The cathode 28 is for processing or machining the outer surface of the workpiece 14, and in the case of the present invention, it is plate-shaped or profile-shaped. The shape of the cathode 28 need not correspond to the desired or existing contour of the workpiece 14 in the region where the cathode 28 is positioned opposite the workpiece 14 (refer to the vertical cathode 30). The cathode 30 is preferably flexible and linear at a non-deflected position. (See Figs. 2 to 4), but can be adapted when inserted into the non-linear extension recess.

A plurality of electrically insulating spacers 34 are attached to the cathode 30 to prevent the cathode 30 from contacting the inner surface 22 of the recess. In the embodiment according to Fig. 2, these spacers 34 are filaments that are attached to the wire-shaped cathode 30 by a clamp, such as a circular brush.

In the embodiment according to FIG. 3, for example, a block-like or cylindrical spacer 34 is embedded in the flexible cathode 30, injection molded, glued or otherwise attached.

The cathode 30 according to Figure 4 is also laterally flexible and coated with a spacer 34 in the form of an insulator to form a drill shape. The insulator has a helical shape so that the helical electrolyte- threads and the cathode 30 is exposed at the base of the trench.

The electrolyte contains 1 liter of electrolyte and 50g to 400g of salt (in particular 150g to 400g), in particular polyvalent alcohols such as glycols or glycerolvs having an alkaline salt, alcohol, in particular a maximum weight ratio of 20% to 70%, and water as a balance . In particular, the halogen may be contained in an amount of up to 100 g per 1 liter of the electrolyte.

The pH of the electrolyte is up to 6.8 or 9 to 12.

Generally, the electrolyte is treated at a temperature of at most 30 캜, especially 15 캜. The process temperature is particularly 7 ° C to 15 ° C.

The workpiece is preferably a metal workpiece bonded together by laser sintering, for example, and 3D-printed with metal particles having a diameter of 20 [mu] m to 60 [mu] m. This means that the workpiece, which is somewhat exaggeratedly expressed on the inner surface 22 as well as on the outer surface, is constructed as a non-cut polystyrene body consisting of a plurality of beads.

To grind the outer and inner surfaces 22, the workpiece is pulled back and forth through the electrolyte 12 by the motor drive device 20. The cathode 28 is moved with them because they are connected to the holding device 16 by a coupling element, shown in phantom.

The cathode 30 is disposed in advance in the recess. The spacer 34 allows the electrolyte 12 to flow to the recessed end of the workpiece side. To this end, in the case of the spacer 34 according to FIG. 3, for example, an axial groove is provided on the outer shell surface of the spacer 34.

The current, for example, the ripple current is applied at a voltage of 10 V to 40 V and a current intensity of 0.0003 A / mm 2 to 0.01 A / mm 2. The current application time is between 30 seconds and 1200 seconds depending on the material of the workpiece and the initial roughness.

Because the electrolyte 12 in the recess region does not have an optimum effect between the recess and the spacer 34, the cathode 30 is first moved to a particular position, in particular with reference to FIG. 3, And moves in a slightly axial direction. After polishing is performed prior to the first polishing step between the spacers 34, after adjustment, these spacers 34 are moved to the previous polished area so that the previous support is polished.

For uniform polishing, it may be useful to have the spacing between adjacent spacers 34 equal to the length of the spacers so that the cathodes are shifted by the length of spacers 34 between polishing steps.

The movement of the cathode 30 can be done manually, mainly when the workpiece 14 is stationary and fixed within the electrolyte 12 by the motor. Alternatively, the movement of the cathode 30 by the motor may be useful.

To this end, Fig. 1 schematically shows an exchange holder 38 provided for fixing the cathode 30 provided with current and / or electrolyte connection portions. The quick-change system in the exchange holder 38 allows a new or other cathode 30 to be inserted quickly. The exchange holder 38 may also include a drive 39 for moving the cathode 30. For example, the exchange holder 38 is mounted to the holding device 16 to move the cathode 30 stepwise or slowly continuously in the recess.

The cathode 30 shown in Fig. 4 is rotated so that the complete inner surface can be processed and the spacer 34 temporarily shields only the support on the inner surface 22.

For optimal processing, the workpiece 14 may be moved, for example, using a circulation pump 40 having an inlet on one side of the container 10 and an outlet on the opposite side, or alternatively, Flow can be useful to implement.

Make sure that electrolyte flows through the recess. This can be done, for example, by reciprocating the cathode 30 or by rotating the cathode 30 (see Figure 4), or by having a separate pump for the electrolyte seated in the inlet of the recess. Feeding or conveying the electrolyte in the recess can also be performed through the hollow cathode 30. [

In the case of 3D products, roughness of about RZ 60 is generated with respect to the above-mentioned particle diameter, and roughness is controlled by RZ 3 to 4 by the polishing process.

This device and method is especially used for 3D printing parts for aircraft, such as engine parts with cooling ducts embedded during printing. It is possible by machining described above to remove the support surface or support ribs created during 3D printing or to selectively create openings in the generally inaccessible inner ribs so that the flow channels are formed here.

However, the cathode 30 can be printed simultaneously with 3D printing, so that it can be connected to the inner surface 22 only through a thin support wall that must be removed, for example, and then exposed and connected to the cable only. Further, since the support wall is made of an insulating material, it can be considered that it exists during polishing.

The cathode 28 may also be fabricated by a generative method. For example, it is possible to manufacture the cathode 28 in the same manner as the workpiece 14.

For workpieces with edges, there is an increased charge density in the edge region during electrolytic processing. The cathode 28 may be tailored for any desired outer geometry of the workpiece. To this end, a 2D or 3D simulation program is used in which electrolytic treatment is also taken into account, i.e. the electrical and / or magnetic field that occurs later in the post-processing of the workpiece is simulated. The constant current density between the cathode and the opposing face of the workpiece is additionally specified as a prerequisite in the simulation program. Once the side of the cathode toward the workpiece is determined, the cathode can be fabricated using a generative method based on the external geometry identified in the simulation program. Cathodes manufactured in this manner are used in the methods described above and in the methods described below.

In electrolytic processing methods, the connection of the anode to the workpiece, or more precisely the contact of the anode, can be problematic. Here, black spots may appear after processing. To avoid this and also to realize effective processing of the workpiece, the anode can be produced with the workpiece by a generative method, for example laser sintering. In this case, the bearing is a so-called support structure, for example a support plate, connected to a power source. The black spots on this support structure are not a drawback since the support structure is removed after processing of the workpiece, in particular by spark erosion.

In addition, a plurality of workpieces can be produced on the same support structure and electrolytically treated.

Fig. 5 shows a support plate 50 that has been printed with or otherwise more generatively produced with the workpiece 14. Although the support plate 50 and the workpiece 14 are one component, only the support plate 50 is shown hatched for better distinction than the two sections. On the other hand, the workpiece 14 is drawn as a block. Actually, the two sections change to one another.

However, the support plate 50 does not necessarily have to be in the form of a plate. It can generally have any desired shape and can constitute a support structure.

Here, a single workpiece 14 on the backing plate is shown by way of example only. Preferably, the plurality of workpieces 14 are on the same support plate 50.

The lower surface of the support plate 50 lies completely on the tool surface, the entire surface on the multiple component holding apparatus. The holding device includes an electrically insulated base plate (52) in which an electrically springable contact pin (54) is guided. Contact pin 54 is connected to power supply 20 through a line. The bearing plate 56 under the base plate 52 forms a holding device together with the base plate 52. Figure 5 shows a plurality of cathodes 28 for external processing. These cathodes 28 are produced simultaneously or separately with the workpiece 14 to ensure a uniform gap 58 or a specific gap 58 between the side 60 facing the workpiece 14 and the workpiece 14 .

The cathode 28 can be mounted through the electrical insulation mount 62 in the opening created in the support plate 50 to obtain a releasable plug connection.

Figure 5 also shows the recess to be processed in the workpiece 14 and the cathode 32 inserted therein. The cathode 32 is mounted to an electrically insulating cathode receptacle 64 and the cathode receptacle 64 is attached to the holding device 16 in turn.

The electrolyte from the second container 66 is pumped directly into the container 10 through the line 70 by the pump 68 and also through the line 72, the connecting portion 74 and the cathode 32, It is pumped directly into the recess through an internal duct.

10; Container 12; Electrolyte
14; Workpiece 16; Holding device
18; A linear guide 20; Motor drive device
22; An inner surface 24; cable
26; Power supply 28; Cathode
30; Cathode 32; Cable, Kesod
34; Spacers 36; home
38; Exchange holder 39; Driving device
40; Circulation pump 50; Support plate
52; Base plate 54; Contact pin
56; Bearing plate 58; gap
60; Side 62; Mounting portion
64; Cathode receptacle 66; Second container

Claims (25)

A method of electrolytically polishing a recessed inner surface (22) of a metal workpiece, in particular a metallic workpiece (14) produced by a production process,
(A) immersing the workpiece (14) in the electrolyte (12) comprising a salt, water and an alcohol having a minimum weight ratio of 20 to 70% per liter of electrolyte;
(B) connecting the workpiece (14) to a positive pole so that the workpiece (14) forms an anode;
(C) providing the electrolyte (12) and at least one cathode (30) in the recess;
(D) providing relative movement between the electrolyte (12) and the workpiece (14); And
(E) applying a voltage between the anode and the at least one cathode (30);
.
The method according to claim 1,
The workpiece (14) is made of a nickel alloy, a chromium alloy, or a light metal.
3. The method according to claim 1 or 2,
The cathode 28, 30 is connected to the cathode of the power source 26 by an electrical line and is inserted in the recess of the workpiece 14 for treatment of the inner surface 22 of the recess.
The method of claim 3,
Wherein the cathode (30) is formed to have flexibility.
The method according to claim 3 or 4,
Wherein at least one electrically insulating spacer (34) projects laterally from the cathode (30).
6. The method of claim 5,
Wherein a plurality of axially spaced spacers (34) are provided on the cathode (30).
The method according to claim 5 or 6,
The cathode 30 together with the spacer 34 is formed by a circular brush and the insulating spacer 34 protrudes the filament or the cathode 30 has a spiral shape on the outer surface and a groove for carrying the electrolyte 12 In particular an elongated body having an outer surface (36).
8. The method according to any one of claims 5 to 7,
After the first polishing step, the cathode is moved relative to the workpiece (14) such that the spacer (34) exposes a previously positioned support opposite the workpiece and is subjected to a second polishing step for polishing the support, Way.
9. The method according to any one of claims 1 to 8,
Wherein an outer surface of the workpiece (14) is polished simultaneously with the inner surface (22) by applying the voltage.
10. The method according to any one of claims 1 to 9,
To achieve relative movement between the electrolyte 12 and the workpiece 14 the electrolyte 12 is pumped past the workpiece 14 and the workpiece 14 is moved along the linear guide 18, Wherein the container is moved in the container (10) containing the electrolyte (12).
11. The method according to any one of claims 1 to 10,
Wherein at least one cathode (28) has a surface located and profiled opposite the workpiece (14).
12. The method according to any one of claims 1 to 11,
Wherein the workpiece (14), in particular the support structure forming the at least one cathode (28) and / or the anode, is produced by a production process, in particular by laser sintering.
13. The method of claim 12,
(14) is used in which a cathode (28) forming the anode and / or a support structure (20) printed together by a production method is used, and the support structure is an electrolytic cell Polishing method.
The method according to claim 12 or 13,
Wherein the metal particles having a diameter of 20 占 퐉 to 60 占 퐉 are used for printing.
15. The method according to any one of claims 1 to 14,
During the electrolytic treatment, the workpiece (14) is seated on a support plate (50) constituting the support structure forming the anode according to any one of claims 12 to 14 in particular.
16. The method of claim 15,
Wherein the cathode for external treatment of the workpiece (14) is fixed to the support plate (50) by means of an electrical insulation mounting part (62), in particular by plug connection means.
17. The method according to any one of claims 1 to 16,
Wherein the electrolyte (12) during the treatment has a maximum temperature of 20 占 폚, particularly a temperature of 15 占 폚 and / or a pH value of 6.8 or 9-12.
18. The method according to any one of claims 1 to 17,
The cathode 30 is inserted into the recess and the electrolyte 12 is connected between the cathode 30 and the inner surface 22 thereof opposite the workpiece 14 through a separate electrolyte conduit, Wherein the gap is pumped into the gap.
19. The method according to any one of claims 1 to 18,
Wherein the cathode (30) is introduced into the recesses deeper and deeper by the motor drive device (20) or manually for the recesses.
20. The method according to any one of claims 1 to 19,
The cathode 30 has a side surface 60 facing the workpiece 14 and has a constant gap 58 with respect to a side facing the workpiece 14 prior to processing of the workpiece 14, 30) is formed after the treatment of the workpiece (14) and forms a cathode against the side facing the cathode (30).
A method of manufacturing a cathode (30) for electrolytic processing of a workpiece (14) having sides opposite to the workpiece (14) to be processed to perform the method according to claim 20,
(a) an external geometry of the cathode (28) at least in the region of the side (60) facing the workpiece (14), wherein an electric field and / or a magnetic field existing between the cathode and the workpiece Is determined and the external geometry of the cathode is determined in view of the constant current density on the side of the workpiece (14) facing the cathode (28); And
(b) generating the cathode (28) by a production method that is based on the determined external geometry;
≪ / RTI >
An apparatus for electrolytic anodic polishing of a metallic workpiece (14), particularly a recessed inner surface (22) of a workpiece (14) printed in three dimensions,
A container (10) filled with said electrolyte (12) comprising a salt, water and an alcohol having a minimum weight ratio of 20 to 70% per 1 liter of electrolyte;
A holding device (16) for the workpiece (14);
A cathode movable relative to the recess and having an electrical insulator at its outer portion and connected to the power source (26) by a cable (32); And
On the one hand, a drive provided for generating a relative movement between the electrolyte 12 and / or the cathode 30, on the other hand, the workpiece 14 present in the recess;
And an electrolytic anode polishing apparatus.
23. The method of claim 22,
A lateral flexible cathode 30 is provided and a portion thereof is provided with an electrically protruding electrical insulator to form a spacer 34 which is in the form of a protruding bristle or a helical groove 36 Wherein the cathode is formed in the form of a shell surrounding the core forming the cathode.
24. The method according to claim 22 or 23,
In addition to the cathode (30) introduced into the recess, at least one external cathode (28) is provided for polishing the outer surface of the workpiece (14).
25. The method according to any one of claims 22 to 24,
There is provided an exchange holder 38 for fixing the cathode 30 and the exchange holder 38 includes a power supply and / or an electrolyte connection part and / or a driving part 39 for moving the cathode 30 Electrolytic anode polishers.

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