EP0230391B1 - Apparatus for electrolytically treating selected areas of the surfaces of objects - Google Patents

Abstract

An installation is provided for carrying out localized electrolytic surface treatment, of the type including an electrolyte reservoir (22) and pumping means (19) adapted for feeding the electrolyte to an anodic equipment (1) able to be placed in contact with the surface of the work piece (P) to be treated, a thin electrolyte flow space then being provided, in said equipment, between the surface of the anode (5) and said surface to be treated, the anode (5) and said work piece (P) being connected to the terminals of a DC voltage source, characterized in that it includes suction means (4, 25) connected to said equipment (1) for bringing the electrolyte back to said reservoir (22) after it has passed through said flow space.

Description

The present invention relates to an installation for carrying out localized electrolytic treatments of surfaces, of the type comprising an electrolyte reservoir and pumping means adapted to send the electrolyte to an anode equipment suitable for being brought into contact with a surface. of the part to be treated, the anode and said part being connected to the terminals of a DC voltage source, and suction means being connected to said equipment to bring the electrolyte back to said reservoir after it has crossed a space d flow through said equipment.

These electrolysis treatments can in particular be intended to obtain, on a selected area of the part in question, a preventive function with respect to phenomena of wear or friction, corrosion or even electrical conductivity. The surfaces concerned are located on functional areas of conductive parts (ferrous metals, copper, light alloys). In the case of such deposits, the anode is connected to the positive terminal of the DC voltage source, and the part, constituting the cathode, to the negative terminal of this source. The anode is irrigated with the selected solution. The electrical circuit comes into action when the anodic equipment is positioned on the surface to be treated.

Very adherent, very dense deposits are obtained in a short time, with great precision. Deposits from a few microns μm to a few tenths can be made under conditions of perfect adhesion; they are characterized by often zero porosities and very precise thickness controls (of the order of a micron µm).

Over one hundred primary metals or alloys binary or ternary can be deposited. By way of examples, among the primary metals: copper, nickel, cobalt, tin, cadmium, lead, zinc, silver, gold can be deposited. Binary alloys such as nickel-cobalt, nickel-tungsten are used. Ternary alloys such as nickel / tin / lead or nickel / tin / cadmium are perfectly suited to selective deposits

Excellent results are also obtained in terms of anodic oxidation (chromic, hard, sulfuric or phosphoric) or electrolytic polishing, this by using reverse current, the anode then being replaced by the cathode.

However, in what follows, and to simplify, we will only speak of the installations used for making deposits, the equipment intended to come into contact with the surface of the part to be treated then being called "anodic equipment". It goes without saying, however, that the invention can be implemented, with the same essential characteristics and the same advantages, in anodic oxidation or electrolytic polishing installations.

Installations of the type which has just been defined are already described in documents FR-A-1 165 583 and FR-A-2 331 629, but these only define the very general principle of the installations, without describing the technical details likely to make them effectively operational. Thus, for example, no means is described in these documents to ensure uniform flow of the electrolyte over the surface to be coated.

The aim of the present invention is to provide specific lessons concerning the regularity of the distribution of the electrolyte and other measures relating to their realization. convenient.

To this end, an installation of the general type defined at the start will, in accordance with the present invention, be essentially characterized in that a thin electrolyte flow space is provided, in said equipment, between the surface of the anode and said surface. to be treated, and in that the anode is traversed by a set of fine passages for the flow of the electrolyte from a space formed between the anode and the bottom of the equipment case.

• - la figure 1 est une vue schématique en éléva-tion de face d'une installation conforme à l'invention, mais ne montrant pas l'équipement anodique ;
• - la figure 2 est une vue en élévation de côté de cette installation, montrant en outre l'équipement anodique ;
• - la figure 3 est une vue en plan de dessus de l'installation ;
• - les figures 4, 5 et 6 sont respectivement des vues de dessous en élévation de face et en élévation de côté d'un mode de réalisation d'un équipement anodique muni d'un vibreur pneumatique ;
• - la figure 7 est une vue en coupe d'un équipe-ment anodique seul selon la ligne VII-VII de la figure 8 ;
• - la figure 8 est une vue en coupe selon la ligne VIII-VIII de la figure 7 ;
• - la figure 9 est une vue de dessous agrandie d'un autre mode de réalisation de l'équipement anodique ;
• - la figure 10 est une vue en coupe de l'équipe-ment anodique de la figure 9 selon la ligne X-X de la figure 11 ; et
• - la figure 11 est une vue en coupe selon la ligne XI-XI de la figure 10.

Different embodiments of the invention will now be described by way of non-limiting examples, with reference to the figures of the appended drawings in which:

• - Figure 1 is a schematic elevational front view of an installation according to the invention, but not showing the anode equipment;
• - Figure 2 is a side elevational view of this installation, further showing the anode equipment;
• - Figure 3 is a top plan view of the installation;
• - Figures 4, 5 and 6 are respectively bottom views in front elevation and side elevation of an embodiment of an anode equipment provided with a pneumatic vibrator;
• - Figure 7 is a sectional view of an anodic equipment-only alone along the line VII-VII of Figure 8;
• - Figure 8 is a sectional view along line VIII-VIII of Figure 7;
• - Figure 9 is an enlarged bottom view of another embodiment of the anode equipment;
• - Figure 10 is a sectional view of the anode equipment-ment of Figure 9 along line XX of Figure 11; and
• - Figure 11 is a sectional view along line XI-XI of Figure 10.

In the installation shown diagrammatically in FIGS. 1 to 3, the anode equipment has been globally referenced at 1 in FIGS. 2 and 3. On some mobile carrier trolley generally referenced at 2 are arranged some of the equipment necessary for the electrolytic treatment operations, this trolley being connected to the anode equipment 1 by a pipe for transporting the electrolytic solution, referenced at 4. In FIGS. 1 and 3, a power unit has moreover been generally referenced at 3, supplying the DC voltage necessary for the operations electrolysis and the output terminals of which are connected on the one hand to the anode 5 (for example in graphite) of the anode equipment by a cable 6 and on the other hand to the part to be treated (not shown), which constitutes the cathode, by a cable 7. For simplicity, these cables have only been shown in FIG. 1. In this same figure, reference is made at 8 to an adjustment member for the electrolysis voltage, at 9 a voltmeter indicating the voltage supplied between the cables 6 and 7 and at 10 an ammeter indicating the intensity of the electrolysis current.

As can also be seen in FIGS. 1 to 3, the mobile carriage 2 also carries an electrical box 11 for vacuum control, connected to the power unit 3 by a cable 12 and a connector 13, this unit 11 being provided with a display dial 14 for counting amp hours, and on / off push buttons 15 for controlling the vacuum and 16 for controlling the pump. In 17 and 18, reference has also been made to on / off control members of the power unit 3.

The pump intended to supply the anodic equipment 1 with electrolytic solution is carried by the carriage 2 and has been referenced at 19. Its suction pipe 20 is connected to a buffer tank 21 itself connected to a reservoir of main electrolytic solution 22 via a line 23 provided with an isolation valve 24.

At the top of the reservoir 22 is arranged a turbo-generator 25 capable of creating a depression therein allowing the return of the electrolytic solution by the pipe 4 from the anode equipment 1.

As for the discharge outlet of the pump 19, it is connected to the anode equipment 1 by a supply tube 26 visible in Figures 1, 2, 3 and 6 and which passes inside the transport pipe of the electrolytic solution 4. For their power supply, the pump 19 and the vacuum turbine 25 are connected to the electrical box 11 by electrical cables referenced at 27 in FIG. 2.

Furthermore, the carriage 2 also carries an assembly generally referenced at 28 in FIGS. 1 and 2 and making it possible to have a source of compressed air for adapting the equipment 1 in a pneumatic sander when the coating has been carried out. This is why in FIGS. 5 and 6 there is shown at 29 a pneumatic vibrator capable of being controlled by a lever 30 to subject the anode equipment 1 to vibrations, either during the electrolysis operation, or after this operation, which then makes it possible to carry out sanding after disposal of a material abrasive in the interface between said equipment 1 and the treated part. It should be noted that, when the vibrations are implemented during the electrolysis operation, they make it possible to improve the quality of the deposit and in particular to avoid spikes which could otherwise occur.

We will now describe in more detail the anode equipment 1.

We have seen above that the anode equipment 1 is supplied with electrolytic solution by a supply tube 26. This tube is of relatively small diameter, so that it can cross the entire length of the hose. transport 4. The equipment 1 comprises on this tube 26 a valve for opening and closing the supply of electrolyte. Downstream of this valve 31, the tube 26 passes through a thicker tube 32 constituting at the same time a handle. The electrolytic solution arriving at the equipment 1 through the tube 32 arrives under the graphite anode 5, which has the general shape of a rectangular plate, by being distributed over the entire surface of the underside of the anode and it passes through that -this by a multiplicity of fine passages referenced 33 in FIG. 4. The electrolyte is thus in contact with the part to be coated by the entire surface of the anode 5. In FIG. 4, there is also shown at 34 the fixing screws of the anode 5 on the box 35 of the equipment 1 and at 36 an electrical contact terminal connected to the end of the cable 6. At 37, there is shown in the bottom view of FIG. 4 a suction opening in connection with the end of the transport pipe 4, which, as mentioned above, allows the return of the electrolytic solution in the main tank 22. This suction opening 37 is located at the bottom of a suction groove 38 surrounding the anode 5, with the interposition of a peripheral insulation material 39. Thus, all of the electrolyte from the fine passages 33 cannot escape outside the anode equipment 1, since on each side of the anode it is sucked into the peripheral groove 38, in which is produced a depression due to its communication with the suction opening 37.

It can thus be seen that the invention has the great advantage of not requiring the use of a retention tank placed under the anode equipment 1; this equipment is therefore much more manageable and it is convenient to treat horizontal or vertical surfaces which can be of any size. It could for example be car bodies, but many other fields of application can be envisaged, such as for example in aeronautics, in the field of nuclear industry, electricity, etc.

In the section views of Figures 7 and 8, the same references have been used as possible as in Figures 4, 5 and 6 to designate the same parts of the anode equipment or the like. These figures clearly show the particular shape of the section of the suction groove 38. The suction opening 37 which opens into the bottom of the suction groove 38 communicates with a suction socket 40 which can be connected to the transport hose 4.

In these two figures, it was yet noted in a passage 41 which can be plugged the tube-Power supply 32, and which passes through the housing 35 of the equi-ment to open near the bottom surface 5a of anode 5. We see that between this surface 5 a and the surface 42 of an insulating fixing piece 43 is formed a space 44 for the electrolyte. It is thanks to this space that the electrolyte can be distributed over the entire surface of the anode 5 and consequently cross this anode through all of the fine passages 33.

Finally, reference is made at 45 to a current supply terminal on which the cable 6 can be connected and which is in electrical connection with the anode 5 by means of the electrical contact terminal 36, the threaded end of which receives two nuts 46 between which the terminal 45 is tightened.

FIGS. 9 to 11 represent an alternative embodiment of the anode equipment 1. Here again, as far as possible, the same references have been used as above to designate the same parts of the equipment or similar parts or fulfilling the same role.

In this embodiment, the anode 5 is further surrounded by a suction groove 38 at the bottom of which opens the suction opening 37, this groove being separated from the anode by the peripheral insulation material , for example made of plastic, 39. The operation of this equipment will therefore be quite similar to that of the embodiment of FIGS. 4 to 6.

However, an additional peripheral space 47 is provided, delimited by an inner skirt 48 and an outer skirt 49, the lips of which, constituting crushing joints, are intended to be sealingly in contact with the part to be coated (shown diagrammatically in P in Figures 10 and 11). The peripheral space 47 communicates with a suction socket 50 (see FIGS. 9 and 11) and can thus be evacuated, so that a suction effect is obtained, further reducing the risk of the electrolyte getting escapes outside the anode equipment 1. In FIG. 9, we still have referenced in 51 and 52 two surrounds of plastic or the like, respectively inside the skirts 48 and 49.

In FIGS. 10 and 11, an elastic over-board of the anode 5 is shown by the interposition of a set of springs 53 compressed between the anode 5 and the insulating fixing part 43.

The anode 5 can then be guided by rods such as 54. Thanks to this arrangement, a certain axial mobility is obtained for the anode, which in particular makes it possible to compensate for its wear and to permanently obtain a very small space between the part P and the surface of the anode.

As for the reference 55, it designates a grip handle.

It should be noted that according to an additional variant of the anode equipment 1, the suction cup effect mentioned above could be eliminated by eliminating the external skirt, but by maintaining the internal skirt 48 to increase the seal between the part. P and the peripheral suction groove 38.

Claims (8)

1. Installation for the realisation of localised electrolytic treatments of surfaces, of the type comprising an electrolyte reservoir (22) and pumping means (19) adapted to send the electrolyte to an anodic apparatus (1) adapted to be placed in contact with a surface of the piece (P) to be treated, the anode (5) and the said piece (P) being connected to the terminals of a direct current voltage source (3), suction means (4, 25) being connected to the said apparatus (1) to return the electrolyte to the said reservoir (22) after it has passed a narrow electrolyte flow space formed, in the said apparatus, between the surface of the anode and the said surface to be treated, the anode (5) being traversed by a set of narrow passages (33) for the flow of the electrolyte from a space (44) formed between the anode and the bottom (43) of the casing (35) of the apparatus (1).

2. Installation according to Claim 1, characterised in that the said anodic apparatus (1) comprises, around the anode (5), a suction groove (38) to the bottom of which there opens a suction opening (37) in communication, by a transport pipe (4), with the said reservoir (22), the upper part of the latter being equipped with a pressure reduction turbine (25) effecting, the return of the solution.

3. Installation according to Claim 2, characterised in that the said pumping means (19) are connected to the anodic apparatus (1) by a feed tube (26) passing to the interior of the said transport pipe (4).

4. Installation according to any one of the preceding Claims, characterised in that the anodic apparatus (1) is provided with means adapted to submit it to vibrations, especially a pneumatic vibrator (29).

5. Installation according to any one of the preceding Claims, characterised in that the anodic apparatus comprises, around the anode (5), a peripheral space (47) defined by two skirts (48, 49) the lips of which are intended to be placed in sealed contact with the piece (P) to be treated, it being possible for this space (47) to be connected to a suction intake in order to be placed under negative pressure and thus to subject the apparatus (1) to a suction cup effect.

6. Installation according to any one of the preceding Claims, characterised in that the anode (5) is elastically suspended in the casing (35) of the anodic apparatus (1).

7. Installation according to any one of the preceding Claims, characterised in that the electrolyte reservoir (22), the suction means (25) and an electric control box (11) are carried by a mobile carriage (2) connected for the one part to the anodic apparatus (1) and for the other part to a power unit (3).

8. Installation according to any one of the preceding Claims, wherein the anodic apparatus (1) is replaced by a cathodic apparatus, for utilisation in anodic oxidation or in electrolytic polishing.

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