COUNTER-ELECTRODE FOR ELECTROCHEMICAL METHOD WITH AUTOMATIC ADAPTATION TO THE GEOMETRY OF THE PART TO BE TREATED

Abstract

An electrochemical treatment method includes: implementing an electrolytic cell containing an electrolytic bath; and immersing an electrode and a deformable counter-electrode in the electrolytic bath, both the electrode and the deformable counter-electrode being connected to a source of continuous or pulsed current, the electrode having an electrically-conductive part and the counter-electrode to be brought near the electrode. A geometry of the deformable counter-electrode is adapted automatically, locally, and independently point by point, to a geometry of the electrically-conductive part before the electrochemical treatment is performed.

Description

CROSS-REFERENCE TO PRIOR APPLICATION

Priority is claimed to European Patent Application No. EP 23165472.4, filed on Mar. 30, 2023, the entire disclosure of which is hereby incorporated by reference herein.

FIELD

The present invention relates to the technical field of electrochemical methods, whether by electrodissolution or by electrodeposition, and in particular to a method consisting in using a deformable counter-electrode that adapts to the geometry of a conductive part to be treated, such as a metal part or surface, or even a plastic part or surface filled with metallic particles, so as to promote a homogeneous surface treatment over the entire surface of the part.

BACKGROUND

Electrochemical methods such as electrodissolution and electrodeposition are very widely used in the field of surface finishing of metal parts. These methods are very versatile and allow to treat parts with simple or more complex geometries, whether in a continuous or discontinuous method. Many works or publications describe good practices for implementing these methods.

Electrodissolution methods allow to remove surface material from a conductive part by anode polarization thereof in an appropriate medium. Electrodissolution can be used in particular for machining (electrochemical machining), deburring (electrolytic deburring), surface texturing or roughness reduction (electropolishing). For example, it is necessary in many cases to reduce the roughness of metal parts, since such roughness has a negative impact on:

• • fatigue behavior;
  • corrosion resistance;
  • cleanliness and cleanability of the part;
  • esthetic appearance; etc.

Electrodissolution methods can be applied on the majority of conductive surfaces (steels, alloys of aluminum, titanium, copper, nickel, etc.).

Electrodeposition methods allow to deposit material on a conductive surface by polarization, generally cathode polarization, thereof in an appropriate medium. Electrodeposition is used in the majority of cases to deposit metallic coatings or composite coatings with a metallic matrix, but also allows to generate polymer coatings (electropolymerization) or ceramic coatings (for example, oxide electrodeposition by base generation). As an example, metallic coatings applied by electrodeposition are used in order to improve specific properties of a part, such as:

• • corrosion resistance;
  • abrasion resistance;
  • brightness, by reducing roughness;
  • electrical conductivity; etc.

The large majority of conductive surfaces can be used as a substrate in an electrodeposition method.

The surface treatment by electrodissolution or electrodeposition is a particularly complex issue in the context of additive manufacturing. The latter allows to produce metal parts with complex to very complex geometries. This technique is particularly adapted to parts/products in small series and with high added value. Therefore, the main markets are currently aeronautics, aerospace, the medical field, the military or the energy sector. The parts produced by this technique have high roughness (about 10 to 120 μm Ra, to mention an order of magnitude) in the majority of cases. They are therefore easy to differentiate from foundry parts. Some applications of these parts are compatible with a high roughness, of the level observed upon exiting a machine. Nevertheless, lower roughness is required for the majority of these applications.

It is well known from the state of the art that the kinetics of the dissolution or deposition electrochemical reactions in the methods previously disclosed are proportional to the flow of electric charges received, that is, to the electric current. In the majority of cases, a homogeneous (or otherwise controlled) treatment of the part is sought, characterized by a uniform quantity of material removed or deposited at all points of the part. This therefore requires that the total current applied is distributed as homogeneously as possible over the surface of the part.

It is also well known from the state of the art that the distribution of the current applied between a part having a given geometry and a counter-electrode depends on the geometry of the cell and on the distance between the surface of the part and the counter-electrode (primary current distribution, described by Ohm's law). The characteristics of the electrolyte, the activation overloads at the electrodes as well as the local hydrodynamic conditions in the cell also affect the distribution of the current. In many cases, the primary current distribution constitutes the dominant contribution and allows to evaluate the actual distribution of the current with a good approximation. To favor homogeneous treatment, it is therefore necessary to control the geometry of the electrochemical cell, and in particular, the distance between the part to be treated and its counter-electrode.

Other surface treatment techniques exist to achieve the surface finishing of conductive parts by removing material:

• • mechanical methods such as milling, resurfacing, sanding, tribofinishing, etc. These methods, which do not require counter-electrodes, have limited performance on complex parts, given the accessibility problems and the lack of homogeneity of the treatment. Furthermore, although they can be automated, these methods must be adapted as soon as the geometry of the part changes;
  • chemical methods such as chemical polishing, which do not require counter-electrodes either. Although this method is effective, it is difficult to control for parts with a non-homogeneous geometry, having both high—and therefore reactive—specific surface areas, and low—and therefore not very reactive—specific surface areas. Furthermore, the obtained surface finish, and therefore the final roughness, is fairly limited. The parts thus retain some roughness;
  • commercial methods:

Hirtenberger: an Austrian company offering a surface-finishing machine that uses chemical and electrochemical methods to treat metal parts (EP3551787A1, EP3551786B1, EP33077925B1, WO2020/079245A1);

Extrudehone: a German company that offers surface-finishing techniques of the AFM (Abrasive Flow Machining) type and electrolytic deburring (WO2010/039491A2) as well as a surface-finishing method derived from the electrochemical machining technology (Coolpulse™ method);

Micro Machining Process (MMP): a French-Swiss company that offers a secret method. No patent could be found;

Gpa Innova (Drylite™ method): a Spanish company that offers a surface-finishing method by electrodissolution. The particularity is that the electrolyte, which specifically conducts the current, is contained in a porous solid material. It is therefore a fairly homogeneous method but it is costly (US2020/270761A1, ES2604830B1, ES2682524A1, ES2721170B2, ES2860348A1, etc.).

These commercial methods ordinarily require a first cell development or treatment step before the part can be treated.

It is well known from the state of the art that the main limitation of electrochemical finishing methods is the difficulty to guarantee the homogeneous treatment of the treated part, or of the treated parts in the case of a batch. The difficulty is even more pronounced when the part has complex geometry. The ability to obtain homogeneous treatment is based on the know-how of the person skilled in the art and in all cases requires technical/economic arbitration between the time dedicated to optimizing the treatment cell and the benefit expected in terms of treatment quality.

Electrochemical finishing methods are implemented in several different ways, based on the size and geometry of the parts as well as the size of the batches. In particular, the parts may be treated:

• • in bulk: by placing the parts to be treated in a rotary barrel, which allows to simultaneously treat a large number of parts. In this configuration, the parts are electrically powered by a connector located inside the barrel and a stationary counter-electrode placed outside the barrel;
  • attached: the various parts to be treated are individually attached to a conductive frame and the assembly is immersed in a tank containing the electrolytic solution and a counter-electrode with a studied shape;
  • individually: the part is treated using a customized cell. In this case, a stationary structure allowing to secure the part and its counter-electrodes is generally used. Means for controlling the hydrodynamic conditions inside the cell (forced circulation) may also complete the cell. This approach is generally reserved for larger parts or for small-series parts with high added value.

Bulk treatment has the advantage that it does not require to adapt the cell to the shape of the parts. The tradeoff is that there is no real control over current distribution and therefore over the removal or addition of material. Only the random nature of the motion of the parts in the barrel allows some homogeneity of the treatment. It is therefore a statistical approach. This approach is reserved for batches of low-mass parts whose geometry is not overly complex.

In the case of attached treatments, the distribution and orientation of the parts on the frame will be decisive to control the current distribution and guarantee that all parts are treated equivalently. Quite often, it is necessary to adapt the geometry of the counter-electrode. This is done by adding auxiliary counter-electrodes, placed in well-defined positions, or “current thieves,” intended to homogenize the current distribution. This approach is also applied in the case of individual treatments.

The typical practice therefore consists in manufacturing, on a case-by-case basis, a counter-electrode with a shape that is adapted to the geometry of the treated parts. Thus, any change in the size or shape of the part requires manual modification of the cell. To do this, it is necessary to disassemble the electrodes in place and to modify or build new counter-electrodes. This operation is costly in terms of time and material. In fact, these counter-electrodes must be made of suitable material, quite often copper, stainless steel or even titanium with conductive oxide coating (MMO). These modifications inevitably cause treatment delays and excess costs.

Digital simulation software allow to anticipate and facilitate these modifications. However, the effort required for the simulation work must always be weighed against the benefits thereof. In practice, the use of digital tools is often not very profitable in the case of small batches of parts with highly variable geometries and is often reserved for larger batches of parts with high added value or for which the allowances to be achieved in terms of thickness removed or deposited require high precision. The solution adopted to modify the cells therefore often rests solely on the know-how and experience of the person skilled in the art and is achieved through trial and error.

The topic of surface finishing for metal parts by electrodissolution, when these parts are produced by additive manufacturing, is a much more recent subject, related to the fact that the additive-manufacturing technique itself is still relatively recent. There is therefore less literature on this subject. Nevertheless, patents dedicated to surface-finishing solutions for this type of parts are starting to be published, essentially about chemical solutions, and not specifically the method, such as for example AT520365A1, U.S. Pat. No. 11,136,688B1, US11, 118,283B2, etc

Identically, the topic of surface finishing for metal parts by electrodeposition, when these parts are produced by additive manufacturing, is a significantly more recent subject, related to the fact that the additive-manufacturing technique is still relatively recent. The available literature is therefore also more limited on this subject. Nevertheless, patents dedicated to surface-finishing solutions for these types of parts are starting to be published, essentially for chemical solutions (CN113477941A, for example) applications (U.S. Pat. No. 20,223,02571A1, for example), but not specifically for the method.

Prior art reports several applications for systems allowing to adapt to the shape of an object or to adapt the shape of an object. The following applications may thus be cited:

• • profile copier. The profile copier allows to copy a profile, quite often only in two dimensions, so as to allow its transfer onto an object to be machined such as a floor board, for example. Several patents address this type of system, for example to mold surfaces (U.S. Pat. No. 2,949,674A, WO1998/054540A1, EA025074B1) or to prepare cutouts for the passage of pipes (U.S. Pat. No. 9,778,012B1), and with some concepts being more elaborate than others (U.S. Pat. No. 4,959,909A). These systems are often limited to two dimensions;
  • mechanical feeler for molding surfaces. In these applications, the system allows to duplicate the surface and forward the recorded profile to a system, which thus allows the object to be reconstructed (U.S. Pat. No. 5,193,285A) or even displayed (EP0366053B1). These systems allow to transfer an image of the surface to be treated in order to exploit it. No subsequent action is expected a priori;
  • flexible surface. For some applications, the patented equipment flexibly adapts to a surface with which it is kept in contact (for example, a razor blade: WO1995/029798A1);
  • digitally-controlled geometry modification. Some applications require to adapt, dynamically or not dynamically, a geometry to the surface of an object but without touching it. This therefore requires to know in advance the parameters of the object to be treated and therefore requires a dynamic system to put the surface in place. This is in particular the case for some space-optics systems, for which the mirrors are placed on cylinders allowing them to be precisely oriented and therefore allowing adaptation of the surface. These systems adapt according to a plan defined in advance, using mechanical means.

Prior art does not practically and effectively solve the problem of the recurring change from one shape or geometry to another in the context of electrochemical finishing methods. The change or adaptation of the treatment cell occurs manually and empirically, sometimes with the help of digital simulation results.

No reference identified in the prior art describes a method for automating the adaptation of the electrochemical cell. A broader search reveals inventions in the prior art for reproducing a surface geometry, in an analog or digital manner, for molding more flexibly a surface with which the object is placed in contact or for modifying the geometry of a device based on a plan using mechanical actuators. It was not possible to identify any invention allowing the positioning at a defined distance from the surface of a part that is not initially known.

SUMMARY

In an embodiment, the present invention provides an electrochemical treatment method, comprising: implementing an electrolytic cell containing an electrolytic bath; and immersing an electrode and a deformable counter-electrode in the electrolytic bath, both the electrode and the deformable counter-electrode being connected to a source of continuous or pulsed current, the electrode comprising an electrically-conductive part and the counter-electrode being configured to be brought near the electrode, wherein a geometry of the deformable counter-electrode is adapted automatically, locally, and independently point by point, to a geometry of the electrically-conductive part before the electrochemical treatment is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:

FIG. 1 schematically shows the principle of the invention showing a counter-electrode whose geometry self-adapts to the shape of the part to be treated, with the three positions of the counter-electrode of the device, namely a first initial or folded position (A), a second position for contact and locking of the bars (B) and a third retracted position for the treatment (C).

FIG. 2 schematically shows a conventional cell for implementing an electrochemical method (electrodissolution/electrodeposition or other) with its various component elements.

FIG. 3 schematically shows two particular embodiments of the invention for the cell geometry (cylindrical and with square base).

FIG. 4 schematically shows two particular embodiments of the invention for the transfer of electric current into the bars.

FIG. 5 schematically shows a system for treating parts in parallel (or simultaneously), according to the invention.

DETAILED DESCRIPTION

In an embodiment, the present invention provides a system and a method allowing to automatically adapt a cell for electrodissolution, electrodeposition, or any other method for electrochemical treatment, to the complex geometry of a conductive part. The system will allow to quickly and automatically pass from one geometry to another, thus allowing increased productivity and reduced costs to perform these treatments. The invention may also help develop electrochemical treatments, without having to worry about the effect of the counter-electrode on the method and the parameters developed.

Furthermore, according to an embodiment it is possible to adapt the invention to treat several parts in parallel.

A first aspect of the present invention relates to an electrochemical treatment method implementing an electrolytic cell containing an electrolytic bath in which an electrode and a deformable counter-electrode are immersed, both connected to a source of continuous or pulsed current, the electrode being made up of an electrically-conductive part and the counter-electrode being so designed that it can be brought near the electrode, wherein the geometry of the deformable counter-electrode is adapted automatically, locally and independently point by point, to the geometry of the electrically-conductive part before said electrochemical treatment occurs.

According to preferred embodiments of the invention, the method further comprises at least one of the following features or an appropriate combination thereof:

• • said automatic, locally and independently point-by-point adaptation of the geometry of the deformable counter-electrode to the geometry of the electrically-conductive part consists in bringing together, two by two, corresponding points of the respective surfaces of the deformable counter-electrode and of the electrically-conductive part, at a distance that is chosen to limit the electrical resistance in the electrolyte and to favor a homogeneous distribution of the electric current on the surface of the electrically-conductive part;
  • the electrically-conductive part used is a metal part, a composite part with a metallic fraction in its mass or a metal or non-metal part coated with a metal layer;
  • the deformable counter-electrode is cathodically polarized relative to the electrically-conductive part so as to cause electrochemical dissolution of the surface of the electrically-conductive part, in the case when said electrochemical treatment method is a method for electrochemical machining or a method for electrolytic polishing;
  • the deformable counter-electrode is anodically polarized relative to the electrically-conductive part so as to cause the growth of a solid film on the surface of the electrically-conductive part, in the case when said electrochemical treatment method is a method for electrodeposition, electropolymerization or precipitation by base generation;
  • the automatic adaptation of the geometry of the deformable counter-electrode to the electrically-conductive part is achieved by bringing the deformable counter-electrode into mechanical contact with the electrically-conductive part beforehand, and before it is retracted to the chosen distance, so as to mold the shape of the electrically-conductive part at the level of the deformable counter-electrode whose outer surface thus takes the shape of the electrically-conductive part;
  • the automatic adaptation of the geometry of the counter-electrode to the electrically-conductive part is achieved without contact, by deforming the counter-electrode by means of actuators based on a plan of the part provided in digital form.

Another aspect of the present invention relates to an apparatus intended for implementing the aforementioned method, comprising at least the following elements:

• • an electrolytic cell with an electrolytic bath intended for said electrochemical treatment, in which the electrically-conductive part and the deformable counter-electrode are immersed;
  • a source of continuous or pulsed current to which the electrically-conductive part and the deformable counter-electrode are connected with opposite polarities; and
  • a mechanism achieving said adaptation, automatically, locally and independently point by point, of the geometry of the deformable counter-electrode to the electrically-conductive part.

According to preferred embodiments of the invention, the apparatus further comprises at least one of the following features or an appropriate combination thereof:

• • the deformable counter-electrode is integrated into the walls of the electrolytic cell, such that at least one of its faces is located outside the cell, or is separated from the walls of the cell such that the deformable counter-electrode is at least partially immersed inside the cell;
  • the deformable counter-electrode comprises a grid or a plate pierced with orifices and a plurality of electrically-conductive bars, designed to slide independently from one another in the orifices of the plate from a distal position to a proximal position with said part, with an intermediate contact position, and vice versa;
  • the bars are solid bars or bars that are sealed against the electrolytic liquid or hollow bars inside which the bath can penetrate or be forced to circulate;
  • the deformable counter-electrode comprises a plurality of electrically-conductive bars cooperating with a plurality of removable elements having a diameter that is greater than that of said bars, thus ensuring that no lateral point of the deformable counter-electrode is below a specific distance from the object to be treated;
  • said bars perform both the function required for the electrochemical treatment and the function of guiding the various bars, thus allowing to do without the grid or plate pierced with orifices;
  • the mechanism that automatically adapts the geometry of the deformable counter-electrode to the electrically-conductive part comprises mechanical, hydraulic and/or electric actuators allowing to set in motion either only the bars, with the plate remaining stationary, or the assembly of the plate and the bars secured thereto;
  • the bars can be secured to the grid by cylinders, jaws, a stretched wire or a magnetic system;
  • the deformable counter-electrode comprises a deformable outer surface allowing to mold, by perfect contact, the outer surface of the part and to create a negative thereof, and the apparatus comprises means for mechanically freezing the shape of the deformable outer surface, once it has molded the outer surface of the part by perfect contact, and for retracting the frozen shape to a fixed or chosen distance from the outer surface of the part;
  • the system having a deformable outer surface is a retractable shell or a net.

The invention also relates to a use of the aforementioned apparatus, in the context of an electrochemical treatment method for an electrically-conductive part, wherein:

• • either the plate and the bars as above, or the deformable outer surface as above, constituting the deformable counter-electrode are moved from an initial position, optionally defined by a plan, toward a surface of the part to be treated until at least part of the deformable counter-electrode is in contact with the surface of the part or has reached a predetermined position;
  • the bars are secured to the plate so as to freeze their relative position with respect to the plate, or the deformable outer surface is mechanically frozen;
  • the assembly formed by the plate and bars, respectively the mechanically-frozen deformable outer surface, is retracted by a specific distance relative to the part;
  • the electrochemical treatment method is applied.

In an embodiment the present invention uses a counter-electrode 10 having a series of conductive bars or tubes 1, that can slide through a grid or plate 2, pierced with holes in order to allow the sliding of the bars 1. The bars 1 are also electrically connected to a current source 3, necessary to ensure the electrochemical treatments.

This assembly shown in FIG. 1 is used to mold the surface of the part to be treated 4 and to perform the electrochemical treatment as follows:

• • the grid 2 and the bars 1 are brought toward the part to be treated 4 for example using a rail 5 to mold the surface of the part 4 by contact therewith;
  • the bars 1 are each blocked relative to the grid 2 in the desired position;
  • the grid 2 with the bars that are secured thereto is retracted by a determined distance D;
  • the electrodissolution or electrodeposition method per se is then implemented.

These steps are also shown in FIG. 1 for a single series of bars. The invention also of course applies in the case of several series of bars placed behind one another.

After treatment, the assembly made up of the grid 2 and bars 1 is retracted and placed back in initial position 6, optionally by bearing on a stop. This allows to advantageously eliminate any complex mechanical element. Furthermore, another advantage of the system is that it is not necessary to have or to account for any information regarding the initial geometry of the part.

With this system, it is thus always possible to ensure a more homogeneous distribution of the current on the surface of the part.

Embodiments of the invention describing an electrochemical cell 11 used for electrodissolution or electrodeposition, as shown schematically in FIG. 2, are presented hereinafter.

The cell comprises a series of bars 1 (FIG. 1) that are electrically-conductive and made from suitable material depending on the electrodissolution or electrodeposition method and on the nature of the parts to be treated. These bars may or may not be conical, may or may not be partially covered with insulating material, and may be hollow or solid. If the bars are hollow (tubes), this allows the electrodissolution fluid to pass homogeneously in the cell. The bars may also have a constant or non-constant cross-section, the end of the bar for example may be larger than its body. If the bars are hollow, and therefore if the electrolyte 7 is injected therethrough, it is possible to provide a jet at their ends so as to modify the flow of electrolyte 7 at their outlet.

The bars may also have a size (diameter) ranging from several mm to several cm and be deposited in the space according to adapted density in order to homogeneously distribute the current. As an informal order of magnitude, a distribution from about one bar per cm² (for the smallest bars) to about ten cm² (for the largest bars) seems appropriate. The finer the bar distribution is and the higher the bar density is, the more homogeneous the current distribution is. However, the presence of too many bars risks disrupting the motion of the electrolyte flow.

The cell 11 also comprises a grid 2 (FIG. 1) pierced with holes having a diameter adapted to the diameter of the bars 1. This grid will be non-conductive, for example made of polymer materials and having a thickness comprised between 2 mm and 15 mm. The latter may be replaced by two parallel sheets of thinner thickness, from about 2 mm to 5 mm. The grid will be pierced with a number of holes adapted to the size of the part to be treated. Depending on the case, this grid may be cylindrical or may be divided into several segments (see FIG. 3).

Regarding the system for moving the bars 1 and/or the grid 2 bearing the bars 1, the grid 2 may be set in motion using a cylinder or any other mechanical, pneumatic or electric system, being or not mounted on a rail 5, while the bars 1 may be set in motion relative to the grid, with the grid 2 in this case remaining in the fixed position, either collectively, in particular if this positioning is done vertically, gravity constituting the driving force for moving the bars, or individually using any appropriate system (mechanical, electrical or pneumatic).

The aforementioned system of bars sliding within a fixed grid may also be replaced by a single system of bars performing both the required function for electrochemical treatment and for guiding the various bars. This allows to do without the fixed frame, while ensuring the function of the invention.

In an variant to the proposed system, an additional set of bars having a diameter that is larger than the diameter of the bars used in the grid may also be introduced between the bars 1 and the part to be treated 4, such that it is possible to ensure that no electrode is laterally too close to the part to be treated. These additional bars mold the shape of the part, then reproduce it on the bars 1 and are ultimately removed from the bath. The bars 1 thus placed are next positioned to perform the treatment.

Once the bars 1 mold the shape of the part 4 by contact therewith, they are next kept in place for example using cylinders, jaws (see below), using a stretched wire (see below), a magnetic system, etc.

The distance between the bars 1 and the part 4 can be adjusted according to the invention, from several mm to several cm, the chosen value being determined to allow limiting of the electrical resistance in the electrolyte and to ensure homogeneous distribution of the current.

Regarding the conductors required for the electrical connection of the bars, the connection may for example be achieved by wires preferably connected to the back of the bars by a system of jaws 21 (FIG. 4A) or even by a system of transverse conductive wires 22 powered on (FIG. 4B). It should be noted that these last two systems also allow the bars to be blocked in position as indicated above. The wires must in this case be electrical conductors and the cross-section of the wires must be adapted to the electrical method used and to the current that will travel through them (several mm²).

The stirring of the electrolyte 7 must be set in motion and regularly brought around the part to be treated using a pump or any other system allowing liquids to be set in motion, for example one or several blades, etc. The inflow of electrolyte must be adapted to the volume of the bath and to the surface-treatment method and it must be brought to the part homogeneously, preferably from bottom to top.

A thermostating system 17 must be provided. The electrolyte 7 must be kept within its operating temperature range using a heating/cooling system. The power of the latter depends on the power used to perform the surface treatment, typically from 50 to 600 W/dm² of part surface to be treated.

Regarding the composition of the tanks, in particular the walls of the treatment cell, they must be made of materials that are compatible with the electrolyte used for the treatments. They may therefore be made of a polymer material or of metal, depending on the case.

The atmosphere (12) above the cell may or may not be controlled. The surface treatment can cause the formation of various gases that may require to be evacuated. Adequate ventilation is therefore necessary. Some electrolytes are hygroscopic: it may therefore also be necessary to use a protective atmosphere over the system (N2 for example).

The electrolytes (or charge carriers) 7 may be in liquid or solid form.

The current source must bring adapted current and/or voltage. Depending on the use, the current will preferably range between 0.1 and 100 A/dm². The voltage will preferably range between 1 and 600 V. The current may be applied continuously or pulsed for a duration ranging from 0.1 to 1000 ms.

The system according to the present invention may be used in the form of a surface-treatment machine implemented directly on site or not.

According to embodiment variants, the invention may also be comprise:

• • using an alternative system to mold the surface of the part, and thus to create a “negative” thereof, for example by using a shell of variable form and retractable. It would also be possible to use a net to mold the surface of the part, freeze it and then retract it;
  • adapting/controlling the position of the cylinders (of the counter-electrode) based on a plan introduced in digital form into the machine;
  • simultaneously treating several parts in parallel as shown in FIG. 5.

According to other embodiments of the invention, the proposed system may be used in order to:

• • apply the method for surface finishing methods in the case of chemical methods, taking advantage of hollow tubes to provide fresh electrolyte as close as possible to the part;
  • using the system to sand parts automatically and homogeneously, optionally by repeating the treatment several times and ensuring a rotation of the part between treatments;
  • automating the surface treatment of parts, whether conductive or not, by adapting the treatment source (current, abrasive chemical product) and its position on the surface of the part.

According to still another embodiment of the invention, the electrolytic cell is a tubular cell, the two bottom walls of which would be movable, provided with a seal to ensure tightness and pierced so as to allow the electrodes to pass, with adequate tightness.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.

The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.

Claims

1. An electrochemical treatment method, comprising: implementing an electrolytic cell containing an electrolytic bath; andimmersing an electrode and a deformable counter-electrode in the electrolytic bath, both the electrode and the deformable counter-electrode being connected to a source of continuous or pulsed current, the electrode comprising an electrically-conductive part and the counter-electrode being configured to be brought near the electrode,wherein a geometry of the deformable counter-electrode is adapted automatically, locally, and independently point by point, to a geometry of the electrically-conductive part before the electrochemical treatment is performed.

2. The method of claim 1, wherein the automatic adaptation, locally and independently point by point, of the geometry of the deformable counter-electrode to the geometry of the electrically-conductive part comprises bringing together, two by two, corresponding points of respective surfaces of the deformable counter-electrode and of the electrically-conductive part, at a distance chosen to limit an electrical resistance in the electrolyte and to favor homogeneous distribution of electric current on a surface of the electrically-conductive part.

3. The method of claim 1, wherein the electrically-conductive part comprises a metal part, a composite part comprising a metallic fraction in its mass, or a metal or non-metal part coated with a layer of metal.

4. The method of claim 1, wherein the deformable counter-electrode is cathodically polarized relative to the electrically-conductive part so as to cause an electrochemical dissolution of a surface of the electrically-conductive part, based on the electrochemical treatment method comprising a method for electrochemical machining or a method for electrolytic polishing.

5. The method of claim 1, wherein the deformable counter-electrode is anodically polarized relative to the electrically-conductive part so as to cause growth of a solid film on a surface of the electrically-conductive part, based on the electrochemical treatment method comprising an electrodeposition method, an electropolymerization method, or a precipitation method by base generation.

6. The method of claim 2, wherein the automatic adaptation of the geometry of the deformable counter-electrode to the electrically-conductive part is achieved by bringing the deformable counter-electrode into mechanical contact with the electrically-conductive part beforehand, and before the electrically-conductive part is retracted to a chosen distance, so as to mold a shape of the electrically-conductive part at a level of the deformable counter-electrode whose outer surface thus assumes a shape of the electrically-conductive part.

7. The method of claim 2, wherein the automatic adaptation of the geometry of the counter-electrode to the electrically-conductive part is achieved without contact, by deforming the counter-electrode using actuators based on a plan of the part provided in digital form.

8. An apparatus intended for implementing the method of claim 1, the apparatus comprising: the electrolytic cell containing the electrolytic bath for the electrochemical treatment, in which the electrically-conductive part and the deformable counter-electrode are immersed;a source of continuous or pulsed current to which the electrically-conductive part and the deformable counter-electrode are connected with opposite polarities; anda mechanism configured to achieve the automatic adaptation, locally and independently point by point, of the geometry of the deformable counter-electrode to the electrically-conductive part.

9. The apparatus of claim 8, wherein the deformable counter-electrode is integrated into walls of the electrolytic cell, such that at least one face of the deformable counter-electrode is located outside the electrolytic cell, or is separated from walls of the electrolytic cell such that the deformable counter-electrode is at least partially immersed inside the electrolytic cell.

10. The apparatus of claim 8, wherein the deformable counter-electrode comprises a grid or a plate pierced with orifices and a plurality of electrically-conductive bars configured to slide independently from one another in the orifices of the plate from a distal position to a proximal position with the part, with an intermediate contact position, and vice versa.

11. The apparatus of claim 10, wherein the plurality of electrically-conductive bars comprise solid bars or bars that are sealed against the electrolytic liquid, or hollow bars inside which the electrolytic bath can penetrate or be forced to circulate.

12. The apparatus of claim 8, wherein the deformable counter-electrode comprises a plurality of electrically-conductive bars cooperating with a plurality of removable elements having a diameter that is greater than a diameter of the plurality of electrically-conductive bars so as to ensure that no lateral point of the deformable counter-electrode is below a specific distance from the object to be treated.

13. The apparatus of claim 10, wherein the plurality of electrically-conductive bars are configured to provide both a function required for the electrochemical treatment and a function of guiding the various electrically-conductive bars, so as to do without the grid or plate pierced with orifices.

14. The apparatus of claim 10, wherein the mechanism comprises mechanical, hydraulic, or electric actuators configured to set in motion either only the electrically-conductive bars, with the plate remaining stationary, or an assembly of the plate and the electrically-conductive bars secured thereto.

15. The apparatus of claim 14, wherein the electrically-conductive bars are securable to the grid by cylinders, jaws, a stretched wire, or a magnetic system.

16. The apparatus of claim 8, wherein the deformable counter-electrode comprises a deformable outer surface allowing to mold, by perfect contact, an outer surface of the part, and to create a negative thereof, and wherein the apparatus comprises means for mechanically freezing a shape of the deformable outer surface, once the apparatus has molded the outer surface of the part by perfect contact as a frozen shape, and for retracting the frozen shape to a fixed or chosen distance from the outer surface of the part.

17. The apparatus of claim 16, wherein the system with a deformable outer surface comprises a retractable shell or a net.

18. A method of using the apparatus of claim 8 in the electrochemical-treatment method for the electrically-conductive part, the method comprising: providing at least part of the deformable counter-electrode as either: the plate pierced with orifices, a grid, and a plurality of electrically-conductive bars configured to slide independently from one another in the orifices of the plate from a distal position to a proximal position with the part, with an intermediate contact position, and vice versa, orthe plate with a deformable outer surface allowing to mold, by perfect contact, an outer surface of the part, and to create a negative thereof,moving the deformable counter-electrode from an initial position toward a surface of the part to be treated until the deformable counter-electrode is in contact with a surface of the part or has reached a predetermined position;securing the bars to the plate so as to mechanically freeze a relative position of the bars with respect to the plate or the deformable outer surface;retracting by a specific distance relative to the part an assembly comprising the plate and bars, respectively to the mechanically-frozen deformable outer surface;applying the electrochemical treatment method.

19. The method of claim 18, wherein the initial position is defined by a plan.