EP3310946B1 - Method for treating surfaces of geometrically complex parts, part-carrying device and treatment device - Google Patents

Description

The present invention generally relates to the electrolytic surface treatment or anodic oxidation, including electroplating, surfaces of metal parts or metallizable plastic (ABS, PA, PP, A8S PC, ...) of complex geometry.

Conventionally, the parts whose faces are intended to be coated by electrolytic treatment, in particular electroplating, are arranged in an electrolysis bath contained in a treatment tank by means of a workpiece constituting the cathode of the device. Typically, the parts are placed in the tank in a fixed position opposite the anodes of the treatment device so that the surfaces to be treated parts as much as possible directly facing the anodes.

In operation, the streamlines in the bath conventionally going from anodes to cathodes primarily reach the surfaces of the parts directly exposed to the anodes. This situation is acceptable for the treatment of parts of simple geometry where the surfaces to be treated parts are all sufficiently exposed to the current lines when the part is in a fixed initial position. On the other hand, in the case of parts of complex geometry, that is to say which in the fixed initial position have surfaces that are totally or partially masked with respect to the anodes, the current lines will only partially reach, or even not at all those surfaces with little or no exposure to the anodes.

It follows that the treatments, in particular the galvanic deposits on the surfaces, are different and not homogeneous. In particular, the thicknesses of the deposits will be different from one surface to another parts and parts will not meet the specifications.

The inventors have studied the impact of current lines on the surfaces of parts to be treated, of complex geometry, as a function of the orientation of the parts relative to the anodes of a treatment device. This study is illustrated schematically by the Figures 1A to 1C .

On the Figure 1A the parts 6 to be treated are in an initial neutral position with respect to the anodes 2. In this case, the impact of the current lines 3 is certainly 80% on the surface A of the parts, but is respectively than 10%, 20% and 10% for surfaces B, C and D.

If parts 1 is rotated 45 ° clockwise or counterclockwise as shown in Figures 1B and C , then the impact of the current lines on the different surfaces is established as follows: Rotate 45 ° clockwise 45 ° anti-clockwise rotation Area Impact% Area Impact% AT 75 AT 75 B 80 B 10 C 10 C 80 D 50 D 50

In general, the present invention therefore aims to solve the problem of the standardization of electrolytic treatment or anodic oxidation, in particular by electroplating, the surfaces of parts of complex geometry and, more particularly, the uniformization of electroplating deposits. .

The documents FR-2832429 and FR-2714079 describe workpiece carriers for electrolytic treatment or anodic oxidation.

In these documents, the objects to be treated are arranged on horizontal rods rotatable about their longitudinal axis. The rotation is carried out once the treatment is completed after removal of the workpiece-holding device from the treatment bath, and is intended to eliminate the excess of treatment bath that may remain in the parts.

The document GB-1,428,856 describes a device in which the workpieces carried by horizontal bars are able to oscillate freely during the treatment to ensure agitation of the treatment bath.

In the field of electrolytic treatment, the following documents are also known: US2008 / 277286A1 , US2005 / 056542A1 , US5360527A , EP1455006A1 , FR2823769A1 and DE664239C .

In order to overcome the aforementioned drawback of the state of the art, the present invention proposes a process for electrolytic treatment or anodic oxidation, in particular electroplating, of parts surfaces, of complex geometry, ensuring optimum access to surfaces. complex parts during treatment.

More particularly, the subject of the present invention is such a method of electrolytic or anodic oxidation treatment which ensures optimal exposure of the surfaces of complex parts to the current lines during the treatment and, consequently, treatment, for example electrolytic deposition, as uniform as possible, of the surfaces of the complex parts.

The invention also relates to an electrolytic treatment device or anodic oxidation designed for the implementation of the method.

Finally, the invention relates to a workpiece capable of ensuring optimal exposure of complex parts surfaces to the current lines during electrolytic treatment or anodic oxidation, including electroplating.

1. a) les pièces de géométrie complexe sont telles que dans une position initiale neutre, des surfaces de ces pièces de géométrie complexe sont peu ou pas atteintes par les lignes de courant s'établissant entre la première et la seconde électrode lors de la mise en oeuvre du procédé de traitement ; et
2. b) pendant le traitement des pièces de géométrie complexe, on soumet les pièces à des rotations séquentielles de part et d'autre de leur position initiale neutre d'un angle pouvant aller jusqu'à 90°, en particulier de 45°, de manière à accroître l'exposition aux lignes de courant des surfaces des pièces de géométrie complexe initialement peu ou pas atteintes.

The above objects are achieved according to the invention by a process of electrolytic treatment or anodic oxidation, in particular electroplating, which comprises the establishment in a so-called initial neutral position, by means of a removable piece-carrier constituting a first electrode in a treatment bath contained in a tank having a second electrode of opposite polarity to the first electrode, of parts of complex geometry, characterized in that;

1. a) the pieces of complex geometry are such that in a neutral initial position, surfaces of these pieces of complex geometry are little or not reached by the current lines established between the first and the second electrode during implementation the treatment process; and
2. b) during the processing of the pieces of complex geometry, the parts are subjected to sequential rotations on either side of their initial neutral position by an angle of up to 90 °, in particular 45 °, so to increase the exposure to the current lines of the surfaces of the parts of complex geometry that were initially little or not reached.

According to the invention, the angles of rotation of the complex parts are chosen as a function of the treatment and the geometry of the parts, so as to optimally expose the surfaces initially not exposed to the current lines established during the treatment.

These sequential rotation angles are generally between 5 and 90 ° on either side of the neutral initial position.

During a treatment, the pieces of complex geometry are rotated sequentially at different angles on either side of their neutral initial position and are maintained in each of these different positions for a sufficient processing time to obtain as uniform a treatment as possible of the surfaces of the parts, in particular an electrolytic deposit, for example by electroplating.

Of course, the method of the invention can be implemented by means of a computer program designed according to the geometric complexity of the parts to be treated and the planned treatment.

• une armature en matériau conducteur de l'électricité ayant des côtés supérieur et inférieur horizontaux réunis par deux côtés latéraux verticaux ;
• des supports mobiles en rotation conçus pour porter les pièces à traiter ;

caractérisé en ce que :

• les supports mobiles sont maintenus verticalement entre les côtés supérieur et inférieur de l'armature de manière à pouvoir pivoter suivant un axe de pivotement vertical ;
• l'extrémité supérieure de chacun des supports mobiles comporte un élément coopérant avec un organe de commande dont l'actionnement fait pivoter séquentiellement les supports mobiles, de préférence d'un angle maximal de 90°, et typiquement jusqu'à un angle d'au moins 45°, de part et d'autre d'une position initiale neutre.

The invention also relates to a workpiece for the electrolytic treatment or anodic oxidation, especially electroplating, complex geometry parts comprising:

• a frame of electrically conductive material having horizontal upper and lower sides united by two vertical lateral sides;
• rotating mobile supports designed to carry the workpieces;

characterized in that

• the movable supports are held vertically between the upper and lower sides of the frame so as to be pivotable along a vertical pivot axis;
• the upper end of each of the movable supports comprises an element cooperating with a control member whose actuation rotates the movable supports sequentially, preferably at a maximum angle of 90 °, and typically up to an angle of minus 45 °, on both sides of a neutral initial position.

• le côté supérieur de l'armature est constitué par une barre conductrice de l'électricité permettant le maintien du dispositif porte-pièces verticalement dans une cuve de traitement et son retrait de la cuve de traitement ;
• l'organe de commande est solidaire du côté supérieur horizontal de l'armature ;
• l'organe de commande est une crémaillère déplaçable linéairement selon un mouvement de va-et-vient et les éléments aux extrémités supérieures des supports mobiles sont des pignons s'engrenant avec la crémaillère ;
• l'organe de commande est conçu pour être raccordé de manière amovible à un actionneur, par exemple un vérin électrique ;
• l'actionneur est solidaire du côté supérieur de l'armature ;
• les supports mobiles sont maintenus verticalement à rotation dans l'armature au moyen de paliers.

The workpiece carrier according to the invention may further comprise the following features taken individually or in any combination thereof:

• the upper side of the frame is constituted by an electrically conductive bar for holding the workpiece device vertically in a treatment tank and its withdrawal from the treatment tank;
• the control member is integral with the upper horizontal side of the frame;
• the control member is a rack movable linearly in a reciprocating motion and the elements at the upper ends of the movable supports are gears meshing with the rack;
• the control member is adapted to be removably connected to an actuator, for example an electric jack;
• the actuator is secured to the upper side of the armature;
• the movable supports are held vertically in rotation in the frame by means of bearings.

In a preferred embodiment of the workpiece carrier of the invention, the parts to be treated are held back-to-back in pairs along the supports.

• au moins une cuve de traitement ayant une surface supérieure ouverte apte à contenir un bain de traitement et dans laquelle est disposée verticalement au moins une première électrode, généralement une anode ;
• un porte-pièces tel que défini ci-dessus constituant une seconde électrode de polarité opposée à la première électrode, généralement une cathode, pouvant être disposé verticalement dans la cuve, de manière que des pièces portées par le porte-pièces soient dans une position initialement neutre face à la première électrode, et
• au moins un actionneur de l'organe de commande du porte-pièces.

The invention also relates to a device for electrolytic treatment or anodic oxidation, in particular electroplating, comprising:

• at least one treatment tank having an open upper surface adapted to contain a treatment bath and in which is arranged vertically at least a first electrode, usually an anode;
• a workpiece carrier as defined above constituting a second electrode of opposite polarity to the first electrode, generally a cathode, which can be arranged vertically in the vessel, so that parts carried by the workpiece carrier are in a position initially neutral facing the first electrode, and
• at least one actuator of the control member of the workpiece holder.

In one embodiment of the invention, the treatment tank comprises, inside the tank, arranged vertically, a first electrode, typically an anode, a third electrode of the same polarity as the first electrode and spaced from this first electrode, the workpiece holder being removably disposed between the first and third electrode.

Preferably, the first and the third electrode are anodes and the workpiece device constitutes a cathode;

In one embodiment of the treatment device according to the invention, the actuator of the control member is integral with the treatment tank.

The treatment device according to the invention may comprise several successive treatment tanks for the complete treatment of the parts, the parts to be treated being placed successively in the different tanks for their treatment by means of a single piece holder according to the invention. In this case, one can provide on each tank an actuator connectable to the control member of the workpiece.

Alternatively, the actuator of the control member may be integral with the workpiece holder and will be transported with the tank-piece holder in the tank until completion of the parts processing process.

Alternatively, the control member comprises a control arm connectable to an external actuator, in particular fixed on a treatment tank.

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

• Figures 1A à 1C, des représentations schématiques de l'impact des lignes sur les surfaces d'une pièce de géométrie complexe en fonction de leur orientation ;
• Figure 2, une vue en perspective d'une réalisation d'un porte-pièces selon l'invention dans sa position initiale neutre ;
• Figures 2A et 2B, des vues de face et de dessus, respectivement du porte-pièces de la Figure 1 ;
• Figure 3, une vue en perspective du porte-pièces de la Figure 1 après une rotation de 45° dans le sens des aiguilles d'une montre par rapport à la position initiale neutre ;
• Figures 3A et 3B, des vues de face et de dessus, respectivement du porte-pièces de la Figure 3 ;
• Figures 4A et 4B, des vues de face et de dessus, respectivement du porte-pièces de la Figure 1 après une rotation de 45° en sens contraire des aiguilles d'une montre par rapport à la position initiale neutre ;
• Figure 5, une vue en perspective schématique du porte-pièces de la Figure 1 mis en place dans une cuve de traitement ;
• Figure 6, une vue de dessus du porte-pièces et de la cuve de traitement de la Figure 5, avec les pièces à traiter dans leur position initiale neutre par rapport aux anodes ;
• Figures 7 et 8, des vues de dessus analogues à la Figure 6, après rotation de 45° des pièces à traiter, respectivement de part et d'autre, par rapport à la position initiale neutre ;
• Figures 9 et 10, des vues schématiques, respectivement de face et en perspective d'une réalisation des porte-pièces et d'une cuve de traitement selon l'invention, le porte-pièces étant sorti de la cuve.

The remainder of the description refers to the appended figures which represent respectively :

• Figures 1A to 1C , schematic representations of the impact of the lines on the surfaces of a piece of complex geometry according to their orientation;
• Figure 2 a perspective view of an embodiment of a workpiece carrier according to the invention in its neutral initial position;
• Figures 2A and 2B , front and top views, respectively of the piece carrier of the Figure 1 ;
• Figure 3 , a perspective view of the workpiece holder of the Figure 1 after a 45 ° rotation clockwise from the neutral initial position;
• Figures 3A and 3B , front and top views, respectively of the piece carrier of the Figure 3 ;
• Figures 4A and 4B , front and top views, respectively of the piece carrier of the Figure 1 after a rotation of 45 ° counterclockwise with respect to the neutral initial position;
• Figure 5 , a schematic perspective view of the workpiece holder of the Figure 1 set up in a treatment tank;
• Figure 6 , a top view of the workpiece carrier and the treatment tank of the Figure 5 , with the parts to be treated in their initial neutral position relative to the anodes;
• Figures 7 and 8 , top views similar to the Figure 6 after rotation of 45 ° parts to be treated respectively on each side, relative to the neutral initial position;
• Figures 9 and 10 , Diagrammatic views, respectively from the front and in perspective of an embodiment of the workpiece carriers and a processing tank according to the invention, the workpiece holder being out of the tank.

Referring to Figures 2 , 2A and 2B , in perspective, in front views and from above, an embodiment of a workpiece carrier 1 according to the invention is shown.

The piece carrier 1 comprises a frame 2 generally rectangular, electroconductive material, having an upper side 2a, a lower side 2b and two lateral sides 2c.

Supports of parts also called candles 3, also of electroconductive material, arranged parallel to the lateral sides 2c of the frame 2, are held between the upper side 2a and the lower side 2b of the frame 2 so as to be rotatable according to a vertical axis on either side of a neutral initial position such that represented on the Figure 2 . This rotary holding can be done by means of bearings 4, for example plain bearings, integral with the upper 2a and lower 2b sides of the frame 2. Fastening means 5 of the parts 6, for example clips, clips or springs , are arranged along the supports. In the embodiment shown, the attachment means 5 of the parts are arranged along the supports 3 so as to maintain the parts 6 in opposite pairs. Of course, other arrangements of the attachment means 5, for example staggered, are possible depending on the geometry of the workpieces and treatments envisaged.

The upper end of each of the rotary supports 3 is provided with a pinion 7 which meshes with a rack 8 secured to the upper side 2a of the armature 2. One end of the rack 8 is integral with a maneuvering arm 9 whose free end can be removably connected to the control rod 11 of a linear actuator 10 such as a cylinder.

A horizontal translation of the rack 8, in one direction or the other, rotates the supports 3, and therefore the parts 6, on either side of the neutral initial position.

Of course, the control of the rotation of the supports 3 and therefore the parts 6 could be achieved by other means such as a cam or screw system.

The upper side 2a of the armature is a bar ensuring the maintenance of the armature 2 in a treatment tank and the supply of current in the rotary supports 3.

As is known, the frame 2, the supports 3 and attachment means 5 parts are electrically conductive material and together constitute an electrode, in particular the cathode of an electrolytic treatment device or anodic oxidation, in particular electroplating, and means are provided, generally on the upper side 2a by connection to a current source.

As an illustration, we have shown on Figures 3 , 3A and 3B , respectively in perspective, from the front and from above, after a rotation of the supports 3 by 45 ° in the direction of clockwise, and on the Figures 4A and 4B , from the front and from above, after a rotation in the opposite direction of 45 °, the positioning of the parts to be treated with respect to the neutral initial position of the Figure 2 . The workpieces thus undergo rotation in an arc and which is oscillatory.

The workpiece carrier 1 according to the invention is particularly designed for use in an electrolytic treatment or anodic oxidation device, in particular the electroplating, and the implementation of the method of the invention.

Referring to Figures 5 to 10 an embodiment of a treatment device according to the invention and the implementation of the method of the invention will now be described.

The Figure 5 represents the workpiece carrier 1 of the invention set up in a treatment tank 20 of a device according to the invention. As shown in Figure 5 , the treatment tank 20 is of generally parallelepiped shape.

The vessel 20 comprises an open upper face 20a, a bottom 20b and two pairs of opposite side walls, a main pair 20c, 20d and a secondary pair 20e, 20f.

A set of electrodes 21a, 21b, typically anodes, is arranged vertically along each of the opposite main side walls 20c, 20d and is for example in the form of vertical and parallel rectangular electroconductive strips.

The workpiece carrier 1 is arranged and held vertically in the tank 20 between the sets of electrodes 21a, 21b, the ends of the upper side 2a of the frame 2 resting on the upper edges of the secondary side walls 20e, 20f, the supports 3 being then vertically arranged in front of the sets of electrodes 21a, 21b, in particular of each of the strips constituting the sets of electrodes.

A linear actuator 10 is fixed to the upper flange of a secondary side wall 20e and removably connected by its control rod 11 to the operating arm 9 of the rack 8.

The Figures 9 and 10 are front and perspective views of a treatment device according to the invention with the workpiece holder 1 outside the treatment tank 20 before or after a treatment. In this embodiment, the linear actuator 10 remains on the tank 20 after disengagement of the operating arm 9 from the rack 8.

Of course, the device according to the invention may comprise several successive tanks as described above for successive successive treatments of the parts 6 carried by the same carrier 1.

If, in the embodiment described above of the device, there is provided an actuator 10 fixed on each treatment tank, it is possible alternatively to provide a single actuator fixed to the upper bar 2a of the frame 2 of the workpiece carrier 1, this actuator being then transported from tank to tank at the same time as the workpiece holder.

An implementation of the method of the invention will now be described in connection with the Figures 5 to 10 and in the context of electrolytic treatment.

As shown by Figures 5 and 6 , the workpiece carrier 1 described above, with the parts 6 of complex geometry to be treated arranged on the rotary supports 3, is placed vertically in a treatment tank 20 containing an electrolyte bath, between the sets of anodes 21a and 21b, the upper bar 20c of the armature 2 resting on opposite sides of the upper open surface 20a constituting the upper edges of the secondary side surfaces 20e, 20f of the vessel 20 not provided with anodes. The bar 2a is connected to a current source, for example by means of a conductive braid or contact ves (not shown). The rotary supports 3 are electrically connected to the bar 2a by means of conductive braids (not shown).

In operation, the armature 2 and the parts 6 form a cathode in front of the anode sets 21a and 21b.

The rack 8 is connected via the operating arm 9 to the rod 11 of a linear actuator 10, for example a cylinder, fixed on the upper edge of the secondary lateral surface 20e of the tank 20.

At this stage, the supports 3, and consequently the parts to be treated 6, are in a neutral initial position in which the "a" surfaces of the parts 6 face the anodes 21a, 21b directly and are directly impacted by the lines current L being established between the anodes and the cathode during the treatment. On the other hand, the surfaces "b" and "c" of the parts 6 which are not in front of the anodes 21a, 21b, are little or not impacted by the current lines L.

During the treatment, the linear actuator 10 is sequentially activated.

In the embodiment shown, it activates a first time the linear actuator 10 to back the rod 11 and thus translate to the right of the rack 8. This translation to the right of the rack 8 has the effect of making rotate the supports 3 in a clockwise direction, here at an angle of 45 ° with respect to the neutral initial position.

Following this rotation of the supports 3, the exposure of the surfaces "b" of the parts 6 to the anodes is increased and the impact of the current lines on these surfaces increases ( Figure 7 ).

The linear actuator 10 is then activated a second time to advance the rod 11 and thus translate to the left of the rack 8. This translation to the left of the rack 8 has the effect of pivoting the supports 3 in the counter-clockwise, here at a 45 ° angle to the neutral initial position.

Following this rotation of the supports 3, the exposure of the surfaces "c" to the anodes is increased and the impact of the current lines L on these surfaces c increases.

Of course, depending on the processing and the complexity of the geometry of the pieces ( Figure 8 ), several rotations can be used during the treatment at an angle between 0 degrees (neutral initial position) and 90 ° on either side of the neutral initial position.

Also, the holding time at each of the selected positions will depend on the processing and the geometric complexity of the parts.

In the case of electrolytic deposition, the angles of rotation and the holding time at the different angular positions will be chosen so as to obtain a deposit which is as homogeneous as possible and in particular of as equal thickness as possible.

The sequence of rotations during a process can be controlled automatically by computer program.

At the end of the treatment, the operating arm 9 is locked in the neutral position and is disconnected from the rod 11 of the actuator and the upper bar 2a is disconnected. The piece carrier 1, with the treated parts 6, is then removed from the tank 20, the actuator 10 remaining fixed on the tank 20.

The piece carrier 1, with the parts 6, can then be placed in another treatment chamber for another electrolytic treatment or other treatment, for example drying, cooking, etc., or the parts 6 can be dismounted from the workpiece holder 1 and stored before shipment.

Claims (14)

1. A method for electrolytic or anodic oxidation surface treatment comprising the positioning in a neutral initial position, by means of a removable part-carrier (1), constituting a first electrode, in a treatment bath contained in a tank (20) including one second electrode (21a, 21b) of polarity opposite to that of the first electrode, of geometrically complex parts (6) made of metal or metallizable plastic material, characterized in that:

   a) the geometrically complex parts (6) are such that, in a neutral initial position, surfaces of these geometrically complex parts (6) are a little or not reached by the lines of current established between the first and the second electrode during the implementation of the treatment method; and

   b) during the treatment of the geometrically complex parts (6), the parts (6) are subjected to sequential rotations on either side of their neutral initial position (0 degree) by an angle liable to go up to 90°, so as to increase the exposure to the lines of current of the part surfaces that are a little or not reached by these lines of current in the neutral initial position.
2. The method of claim 1, characterized in that the angle of rotation of the parts (6) is of 45° on either side of the neutral initial position.
3. The method of claim 1 or 2, characterized in that the parts (6) to be treated are held in the different angular positions resulting from the sequential rotations during a determined time as a function of the treatment and of the geometric complexity of the parts (6).
4. A part-carrier (1) for the electrolytic or anodic oxidation treatment of geometrically complex parts (6), comprising:

   - a reinforcement (2) made of an electricity conductive material having upper (2a) and lower (2b) horizontal sides connected by two vertical lateral sides (2c, 2d);

   - rotatably mobile supports (3) designed to carry the parts (6) to be treated;

   characterized in that:

   - the mobile supports (3) are held vertically between the upper (2a) and lower (2b) sides of the reinforcement (2) so as to be able to pivot about a vertical pivoting axis; and

   - the upper end of each of the mobile supports (3) includes an element (7) cooperating with a control member (8) whose actuation make the mobile supports (3) pivot sequentially, on either side of a neutral initial position.
5. The part-carrier (1) according to claim 4, characterized in that the maximum angle of rotation is of 90°, preferably at least 45°.
6. The part-carrier (1) according to claim 4 or 5, characterized in that the control member (8) is integral with the upper side (2a) of the reinforcement (2).
7. The part-carrier (1) according to any one of claims 4 to 6, characterized in that the upper side (2a) of the reinforcement (2) is consisted of a rod allowing the vertical positioning and holding of the part-carrier (1) in a treatment tank (20) and the supply of current to the part-carrier (1).
8. The part-carrier (1) according to any one of claims 4 to 7, characterized in that the control member (8) is designed to be removably connected to an actuator (10).
9. The part-carrier (1) according to any one of claims 4 to 8, characterized in that the control member (8) is a rack moving linearly according to a reciprocating movement and the elements (7) at the upper ends of the mobile supports (3) are pinions engaging with the rack (8).
10. The part-carrier (1) according to any one of claims 8 to 9, characterized in that the actuator (10) is integral with the part-carrier and transportable with the latter.
11. The part-carrier according to any one of claims 4 to 10, characterized in that the control member (8) comprises a control arm (9) connectable to an external actuator, in particular fixed to a treatment tank.
12. A device for electrolytic or anodic oxidation treatment, characterized in that it comprises:

    - at least one treatment tank (20) having an open upper surface (20a), adapted to contain a treatment bath;

    - at least one first electrode (21a, 21b), preferably an anode, arranged vertically in the tank (20);

    - a part-carrier (1) according to any one of claims 4 to 11, constituting a second electrode, of polarity opposite to that of the first electrode (21a, 21b), which can be arranged vertically in the tank (20), so that geometrically complex parts (6) carried by the part-carrier (1) are in an initially neutral position opposite the first electrode (21a, 21b); and

    - at least one actuator (10) of the control member (8) of the part-carrier (1).
13. The device according to claim 12, characterized in that the first electrode is consisted of two sets of electrodes (21a, 21b), and the part-carrier (1) is placed between the two sets of electrodes.
14. The device according to claim 12 or 13, characterized in that the actuator (10) is integral with the treatment tank (20) or carried on the part-carrier (1).

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