Device for electrochemical surface treatment of an inner surface of a tubular member made of electrically conductive material, in particular a gun barrel, and system comprising such a device

Abstract

A device and system for electrochemical surface treatment of an inner surface of a longitudinal tubular member made of electrically conductive material including: a frame assembly; at least one cathode electrically connected to the tubular member; a longitudinal anode positioned coaxially inside the tubular member; sealed interface means removably cooperating with the tubular member and anode, the sealed interface means including at least first and second inlet / outlet ports connected to a source of treatment liquid and adapted to communicate, in use, with a sealed longitudinal passage formed between the anode and the inner surface of the tubular member; and means for driving the tubular member in rotation about its longitudinal axis. The frame assembly supports the tubular member in a non-vertical orientation and further includes means for putting the anode under traction, acting on at least one of the two ends of the anode to prevent deflection of the anode.

Description

[0001] The technical field of the invention is that of electrochemical surface treatment.

[0002] The present invention concerns a device and a system for the electrochemical surface treatment of an inner surface of a tubular member made of electrically conductive material, in particular a gun barrel. It should be emphasized that the present invention can be applied to the surface treatment of any tubular mechanical part made of electrically conductive material. The electrochemical surface treatment(s) implemented by the present invention can be an electrolytic metal coating, including but not limited to electrolytic chromium (chromium plating) for nickel (nickel plating) deposition, or electrolytic polishing (electropolishing).

[0003] In the field of armaments, which is one of the applications of the present invention, it is known to coat the inner wall of a gun barrel with a thin layer of chromium in order to improve the gun barrel's resistance to wear and friction during the passage of projectiles and, consequently, to increase the number of projectiles that the gun barrel can fire during its service life. In fact, chromium has high hardness and low chemical interaction with other metals, both of which considerably reduce wear on parts. Chromium plating also has the advantage of adding a corrosion-resistant coating to the gun barrel, thus extending the service life of the gun barrel, particularly in damp environments.

[0004] This layer of chromium is usually applied electrolytically. To this end, an anode is inserted coaxially into the gun barrel and along the entire length of the gun barrel. A suitable electrolyte, such as a chromic acid bath, is then circulated in one direction through the gun barrel, between the anode and the inner wall of the gun barrel, while a voltage is applied to the anode and gun barrel. The electric current flowing from the anode to the gun barrel via the electrolyte deposits a thin layer of chromium on the inner surface of the gun barrel.

[0005] Patent GB712314, published on 21 Jul. 1954, discloses such a process for chromium plating the inner surface of a gun barrel electrolytically, as well as an apparatus for carrying out that process. In order to obtain an even deposit, the gun barrel is positioned vertically and rotated about its longitudinal axis.

[0006] This solution is suitable for light- and medium-calibre gun barrels. However, because of the vertical positioning of the gun barrel, this solution has disadvantages when applied to large-calibre gun barrels several metres long, since it requires a very considerable height and suitable handling equipment.

[0007] The present invention thus aims to provide a solution for the electrochemical surface treatment, in particular electrolytic chromium plating, of the inner surface of a tubular member made of electrically conductive material, in particular a large-calibre gun barrel, in a space with a reduced volume in terms of height, while ensuring that the distribution of a metal deposit is as constant as possible in terms of thickness in the case of a metal coating.

[0008] The solution according to the present invention relies on the use of a device enabling the tubular member to be orientated in a non-vertical orientation, such as horizontally, and also comprising both means for putting the anode under traction and means for driving the tubular member in rotation about its longitudinal axis. The means for putting the anode under traction enable the anode to be made as straight as possible and to be kept strictly coaxial with the tubular member so that it remains equidistant from the inner wall of the tubular member, thus preventing its deflexion. The means for driving the tubular member in axial rotation prevent gases, in particular from electrolysis, from accumulating at a given point on the tubular member, a point which would then receive less metal deposit in the case of a metal coating. At the same time, the means for putting the anode under traction and the means for driving the tubular member in axial rotation prevent the tubular member's internal diameter from shrinking, a phenomenon known as the “hourglass effect”, in which the metal deposit presents a profile comparable to that of an hourglass.

[0009] The solution according to the present invention also relies on the use of a system comprising such a device and further comprising alternating circulation means capable of circulating a treatment solution through the tubular member in both directions, in an alternating manner. In the case of a metal coating, the alternating circulation means make it possible to obtain ultimately a metal coating that has deposited with the same metal deposition rate over the entire length of the tubular member, even at its two ends, and thus to avoid deposition occurring more rapidly at one end than at the other, which would lead to the inner surface of the tubular member having a blunderbuss shape.

[0010] The present invention thus relates to a device for electrochemical surface treatment of an inner surface of a longitudinal tubular member made of electrically conductive material, in particular for electrolytic metal coating of an inner wall of a gun barrel, the tubular member having a longitudinal axis and being open at first and second ends, which device comprises:

[0011] a frame assembly configured to support such a tubular member so as to allow the tubular member to rotate about its longitudinal axis;

[0012] at least one cathode intended to be connected to the negative pole of a current source and configured to be electrically connected to the tubular member;

[0013] a longitudinal anode intended to be connected to the positive pole of the current source and configured to be positioned inside the tubular member, coaxially with the longitudinal axis and at least along the entire length of the tubular member;

[0014] sealed interface means configured to removably cooperate with the tubular member at first and second ends of the tubular member and to seal said first and second ends, and to cooperate with the anode to ensure its centering relative to the tubular member, the sealed interface means comprising at least one first inlet and outlet port (or “inlet / outlet port”) adapted to communicate with the first open end of the tubular member and at least one second inlet and outlet port (or “inlet / outlet port”) adapted to communicate with the second open end of the tubular member, so that, in use, a sealed longitudinal passage is formed between the anode and the inner surface of the tubular member from the first to the second end of the tubular member, the inlet and outlet ports being intended to be connected to a source of treatment liquid; and

[0015] means for driving the tubular member in rotation about its longitudinal axis,characterized in that the frame assembly is adapted to support the tubular member in a non-vertical orientation thereof and that the device further comprises means for putting the anode under traction, configured to, when the anode is mounted within the tubular member, act on at least one of the two ends of the anode to prevent deflection of the anode.

[0016] Thanks to the presence of both means for putting the anode under traction and means for driving the tubular member in axial rotation, it can be seen that the occurrence of an “hourglass” effect can be avoided during a metal deposition operation using the device according to the invention. In addition, the presence of means for putting the anode under traction allows to obtain, in use, a satisfactory surface treatment even when the tubular member is positioned horizontally on the frame assembly, even in the case of a tubular member of great length. It is therefore possible to use the device according to the 15 invention in a workshop with reduced volumes in terms of height.

[0017] The device according to the invention can be a chromium plating device, in which case the source of treatment liquid is a chromium plating bath, in particular a chromic acid bath.

[0018] Preferably, the anode comprises a cylindrical rod made of a single piece of conductive metal, particularly copper, and, at each end, a lead sleeve soldered to the rod. Such a lead sleeve improves the anode's resistance to corrosion and gives it sufficient mechanical strength over time.

[0019] Preferably, the means for driving in rotation comprise means for controlling the direction and / or speed of rotation.

[0020] In a particular embodiment, the means for driving the tubular member in rotation are configured to produce an alternating rotational movement of the tubular member, so that, in use, the tubular member is able to be rotated, over a given angular range, alternately in a given direction of rotation and then in the opposite direction of rotation.

[0021] Advantageously, the means for driving in rotation are configured to allow axial rotational movement in either of the two directions of rotation over a maximum angular range of 360 degrees, corresponding to one revolution of the tubular member around its longitudinal axis.

[0022] In a particular embodiment, the means for driving in rotation comprise a rack-and-pinion system, in which the rack is coupled to a motor via a connecting rod and the pinion is coupled to a pulley-belt assembly, which pulley-belt assembly is connected to a roller assembly intended to support the tubular member and the rollers of which are rotatably mounted about axes intended to be parallel to the longitudinal axis of the tubular member. At least some of the rollers are driven in rotation by the pulley-belt assembly, so that they themselves rotate the tubular member.

[0023] Advantageously, the means for putting the anode under traction are configured to allow traction adjustment by screwing the anode onto one of the sealed interface means. Such putting of the anode under traction, by mechanical tightening, is more reliable than putting it under traction using spring.

[0024] Preferably, in use, the tightening torque applied to put the anode under traction is of the order of 130 dN·m.

[0025] In a particular embodiment, the means for putting the anode under traction comprise at least one first threaded bore and at least one second threaded bore provided in the sealed interface means, the or one of the first threaded bores being configured to cooperate with one of the ends of the tubular member, in particular the second end, and the or one of the second threaded bores being configured to cooperate with an external thread provided on the corresponding end region of the anode, said first threaded bore having a thread pitch reversed with respect to the thread pitch of said second threaded bore, so that, in use, when said first threaded bore is screwed onto the end of the tubular member and the other end of the anode is held stationary, the end region of the anode carrying the external thread is caused to screw into said second threaded bore.

[0026] Advantageously, reinforcing rod is provided for removably securing the anode to the sealed interface means at the end region of the anode opposite to the end region carrying the external thread, the rod having first and second external threads which cooperate, respectively, with a third threaded bore of the sealed interface means and a threaded axial hole of the anode. Such a rod increases the strength at the securing area.

[0027] Preferably, the axial threaded hole is provided in the region of the first end of the anode, and the external thread is provided on the region of the second end of the anode.

[0028] Advantageously, the sealed interface means comprise, at the level of the or each first threaded bore, an external hexagonal profile made of electrically insulating material. Such a hexagonal profile is adapted to cooperate with a conventional tool, in particular a wrench suitable for rotation locking or clamping, having a corresponding hexagonal profile.

[0029] In a particular embodiment, the sealed interface means comprise a first and a second interface assembly, the first interface assembly comprising a first module made of electrically insulating material, configured to cooperate with the first end of the tubular member and to be traversed by the anode, and a first module made of electrically conductive material, secured to the first module made of electrically insulating material and configured to cooperate with the first end of the anode, the second interface assembly comprising a second module made of electrically insulating material, configured to cooperate with the second end of the tubular member and to be traversed by the anode, and a second module made of electrically conductive material, secured to the second module made of electrically insulating material and connected to the second end of the anode via the means for putting the anode under traction.

[0030] Preferably, each module made of electrically insulating material is made of PVDF (polyvinylidene fluoride) and each module made of electrically conductive material is made of steel.

[0031] Preferably, a conical sealed connection module made of electrically insulating material and intended to be connected to a source of treatment liquid is secured to each module made of electrically conductive material, each conical module having a converging hole in communication with the inlet / outlet port(s) of the sealed interface means. Such a conical module prevents turbulence and maintains laminar flow.

[0032] Preferably, the at least one cathode is a peripheral cathode comprising a metal rod intended to be positioned outside the tubular member and along a generatrix thereof, the rod carrying at least one flange for connection to the tubular member and a connector module for connecting the rod to the current source, the connector module being secured to the sealed interface means while being in electrical isolation from the anode, so that in use the tubular member takes on the function of cathode.

[0033] Preferably, the modules are secured together by removable fasteners, in particular bolts.

[0034] In a particular embodiment, the frame assembly comprises a support frame and a mobile frame mounted on the support frame and movable relative to the support frame, at least pivotally about a pivot axis, the means for driving the tubular member in rotation being secured to the mobile frame, the amplitude of pivoting of the mobile frame about the pivot axis allowing, in use, the tubular member to be at an angle of inclination, relative to a horizontal plane, comprised between 0 and 90 degrees inclusive.

[0035] Preferably, at least one actuator of the linear cylinder type is connected between the support frame and the mobile frame, one end of the actuator being articulated to the mobile frame about a rotation axis that is parallel to the pivot axis and eccentric with respect to the pivot axis.

[0036] Preferably, the support chassis is a rolling chassis, for example equipped with at least a first wheel assembly and a second wheel assembly.

[0037] The present invention also relates to a system for electrochemical surface treatment of an inner surface of a tubular member made of electrically conductive material, characterized in that it comprises a device as defined above, which system further comprises:

[0038] an electrical circuit comprising a current source whose positive pole is connected to the anode and whose negative pole is connected to the at least one cathode; and

[0039] a hydraulic circuit connected to the first and second inlet and outlet ports of the device and comprising at least one source of treatment liquid and means for circulating treatment liquid, which hydraulic circuit further comprises alternating circulation means capable of circulating the treatment liquid in the longitudinal passage, in a first step from the first end toward the second end, and then in a second step inversely from the second end toward the first end.

[0040] Thanks to the presence of means for putting the anode under traction, means for driving the tubular member in axial rotation, and means for alternately circulating a treatment liquid, the occurrence of a “blunderbuss” phenomenon can be avoided during a metal deposition operation using the system according to the invention.

[0041] The alternating circulation means may include a reversible circulation pump driven by a drive motor capable of rotating in both directions.

[0042] Preferably, the anode is connected to the current source via a first conductive connection element connected on the one hand to the positive pole of the current source and on the other hand to the second module made of electrically conductive material, and the cathode is connected to the current source via a second conductive connection element connected on the one hand to the negative pole of the current source and on the other hand to the connector module.

[0043] Advantageously, the treatment liquid circulation speed is between 0.1 and 5 m / s and the applied current density is from 20 to 60 A / dm2.

[0044] Preferably, the hydraulic circuit comprises a plurality of treatment liquid storage tanks, each tank being associated with at least one pipe for the delivery of the liquid it contains, which pipe is equipped with a solenoid valve, control means being provided to control the solenoid valves and enable one of the storage tanks to be fluidly connected to the device.

[0045] Advantageously the plurality of storage tanks comprises at least one acid etching solution storage tank and at least one basic etching solution or liquid storage tank for carrying out a rinsing operation, at least one chromium-based solution storage tank for carrying out a chromium plating operation, an electropolishing solution storage tank and a neutralization solution or liquid storage tank for removing hexavalent chromium.

[0046] To better illustrate the subject-matter of the present invention, a particular embodiment is described below, with reference to the appended drawings. In these drawings:

[0047] FIG. 1 is a side view of the device according to a particular embodiment of the invention, with a gun barrel supported horizontally;

[0048] FIG. 2 is a perspective view of the device shown in FIG. 1, with brackets added on either side of the support frame;

[0049] FIG. 3 is an enlarged perspective view of the means for driving in rotation, with part of the frame assembly and a section of the barrel omitted for clarity;

[0050] FIG. 4 is an enlarged perspective view of the device at a first end of the tubular member;

[0051] FIG. 5 is a longitudinal section view of the enlarged area shown in FIG. 4;

[0052] FIG. 6 is an enlarged perspective view of the device at a second end of the tubular member;

[0053] FIG. 7 is a longitudinal section view of the enlarged area shown in FIG. 6; and

[0054] FIG. 8 shows a schematic diagram of the system according to the present invention.

[0055] Referring first to FIGS. 1 to 7, it can be seen that the device D for electrochemical surface treatment according to the present invention can be applied to the surface treatment of the inner wall Pi of a gun barrel T, in particular a rifled gun barrel. In the remainder of the description, the term “gun barrel” or “barrel” is therefore used to designate the element to which device D is applied. However, the application of device D according to the invention is not limited to gun barrels T, as the element can be any longitudinal tubular member made of electrically conductive material, including a tubular member of great length.

[0056] As can be seen from FIGS. 1 and 2, the device D according to the invention comprises at least one frame assembly 1, a cathode 2, an anode 3, sealed interface means 4A, 4B, means 5 for driving the gun barrel T in rotation, and means 6 for putting the anode 3 under traction.

[0057] The function of the frame assembly 1 is to support the gun barrel T to be processed, in a non-vertical orientation of the gun barrel T.

[0058] In the particular embodiment shown, the frame assembly 1 comprises a support frame 10 configured to support the barrel T horizontally while allowing it to rotate about its longitudinal axis X0. To this end, the support frame 10 carries the means 5 for driving the barrel T in rotation. The support frame 10 is a mechanically-welded frame, on braked wheels 11, comprising longitudinal members connected by cross-members. As can be seen in FIG. 2, brackets 12 can be provided at each longitudinal end of the support frame 10, to enable the suspension of electrical cables 9 and liquid pipes 17 for connection to the device D. Similarly, a pair of steady blocks 13, forming frames arranged in vertical planes and suitable for the gun barrel T to pass through, can be mounted on the upper longitudinal members of the support frame 10. The upper longitudinal members and the steady blocks 13 are configured in such a way that the longitudinal position of the steady blocks 13 on the support frame 10 is adjustable, thus adapting to the length of the part to be treated.

[0059] Alternatively, the frame assembly 1 could also comprise a mobile frame (not shown) mounted on the support frame 10 and carrying the means 5 for driving the barrel T in rotation. For example, the mobile frame could be mounted so as to be pivotable relative to the support frame 10 about a horizontal pivot axis orthogonal to the longitudinal axis of the support frame 10. The pivoting movement of the mobile frame about the pivot axis could be controlled by a cylinder connected to the support frame 10 and articulated to the mobile frame about a rotation axis parallel to the pivot axis. Thus, in use, an extension of the actuator rod causes the mobile frame, and therefore the gun barrel T it supports, to move to a high position, for example a position in which the longitudinal axis X0 of the gun barrel is horizontal. Conversely, retraction of the actuator rod causes the mobile frame, and hence the gun barrel T, to move to a low position, in which the longitudinal axis X0 of the gun barrel T is at an angle of between 0 and 90 degrees relative to a horizontal plane. It should be emphasized that the actuator could be replaced by any other suitable linear actuator. Thus, such a frame assembly enables the gun barrel T to be positioned at any desired angle of inclination. To ensure that the barrel is held in an axial position relative to the mobile frame, particularly when the angle of inclination is large, an anti-slip ring is mounted around the barrel and comes into abutment with a stop element of the mobile frame.

[0060] The cathode 2, once connected to the negative pole (−) of a current source 8, enables the gun barrel T to take on the function of cathode. As shown in FIGS. 1, 2, 6 and 7, the cathode 2 comprises a metal rod 20 positioned along the barrel T, on the outside of the latter, and connected to the barrel T by electrically conductive connecting flanges 21 fitting around the barrel T. The rod 20 is connected to the current source 8 via a connector module 22. This module 22, made of electrically conductive material, is fitted around a module e 40A, made of electrically insulating material, of the sealed interface means 4A and around the rod 20. A conductive connection element 23 connected to the negative pole (−) of the current source 8 is received in the connector module 22. Thus, once the current source 8 is switched, on, current flows in an electrical circuit CE to the connection element 23, then successively through the connector module 22, the rod 20, the flanges 21 and the wall of the barrel T.

[0061] The anode 3 is a longitudinal cylindrical part made of conductive metal, in particular copper and lead. As can be seen in FIGS. 5 and 7, in the assembled state, the anode 3 is centered coaxially with the gun barrel T and protrudes on either side of the ends E1, E2 of the gun barrel T. An annular channel is formed between the anode 3 and the inner wall surface Pi of the barrel T, which channel defines a longitudinal passage 7 from one open end of the barrel T to the other. Thus, the diameter of the anode 3 is a function of the surface treatment to be applied, for example, the desired thickness of metal deposit, and of the dimensions of the barrel T.

[0062] As shown in FIG. 5, the anode 3 is connected to the positive pole (+) of a current source 8 via a module 41B, made of electrically conductive material, of the sealed interface means 4B. This module 41B accommodates a conductive connection element 30 connected to the current source 8 and cooperates with an end region of the anode 3. In particular, this end region of the anode 3 has an external thread 31 which engages with a threaded bore 413 of the module 41B. Thus, once the current source 8 is switched on, current flows through an electrical circuit CE to the connection element 30, and then through the electrically conductive module 41B and the anode 3. As can be seen in FIG. 7, the other end region of the anode 3 has an axial threaded hole 32. A reinforcing rod 33 enables the anode 3 to be secured, by its threaded end, to another electrically conductive module 41A of the sealed interface means 4A. This reinforcing rod 33 has threaded longitudinal end regions whose external threads engage, respectively, with a threaded bore 413 of the electrically conductive module 41A and with the threaded axial hole 32 of the anode 3.

[0063] The sealed interface means 4A, 4B serves to seal the gun barrel T at each of its two open ends E1, E2, to hold the anode 3 in position in the barrel T and to allow a fluid connection between a treatment liquid source C1 to Cn and the longitudinal passage 7 formed inside the barrel T. The sealed interface means 4A, 4B comprise first 4A and second 4B interface assemblies co-operating, respectively, with the first E1 and second E2 ends of the gun barrel T and the anode 3.

[0064] Referring to FIGS. 6 and 7, it can be seen that the first interface assembly 4A comprises a first module 40A made of electrically insulating material, a first module 41A made of electrically conductive material and a first conical sealed connection module 42A.

[0065] The first module 40A, made of electrically insulating material, is a tubular body made, for example, of PVDF and having a hexagonal external profile section 401, a cylindrical section 402 and an annular section 403. The inner wall of the hexagonal external profile section 401 has internal threads 404 which cooperate with external threads T1 carried by the first end region E1 of the barrel T. In this way, this insulating module 40A is screw-fastened to the first end E1 of barrel T. The cylindrical section 402 is dimensioned so that the connector module 22 fits around it. The through hole 405 of this insulating module 40A is arranged coaxially with the longitudinal axis X0 of the barrel T and the anode 3 so as to open into the barrel T. The annular section 403 has an external diameter greater than the external diameter of the cylindrical section 402, so as to enable this module 40A to be assembled with the first electrically conductive module 41A by means of removable fasteners, in particular bolts 43.

[0066] The first module 41A, made of electrically conductive material, is a tubular body made, for example, of steel and having a cylindrical section 410 interposed between two annular sections 411. The cylindrical section 410 has a cylindrical hole 412 in which the first end region of the anode 3 is positioned. The cylindrical hole 412 is coaxial with the longitudinal axis X0. This section 410 therefore enables positioning, in particular centering, of the anode 3 relative to the barrel T. The threaded bore 413 in engagement with the reinforcing rod 33 opens into this cylindrical hole 412. In this way, the anode 3, with its first end, is secured to the first electrically conductive module 41A. One of the annular sections 411 is in contact with the annular section 403 of the first insulating module 40A, the two modules 40A, 41A being assembled in a sealed manner. The other annular section 411 is in contact with an annular section 420 of the first conical module 42A, the two modules 41A, 42A also being sealed together by means of bolts 43, rings and seals. A plurality of cylindrical channels 414 are arranged around the hole 412 coaxial with the gun barrel T. These channels 414 open on the one hand into the through hole 405 of the first insulating module 40A and on the other hand into a convergent hole 423 of the first conical module 42A.

[0067] The first conical module 42A is a tubular body made of an electrically insulating material, in particular plastic, and having an annular section 420 for securing to the first electrically conductive module 41A, a conical section 421 and a cylindrical section 422. The convergent hole 423 is formed in the conical section 421. A cylindrical inlet / outlet port 424 is formed in the cylindrical section 422. The converging hole 423 opens into the cylindrical inlet / outlet port 424. In this way, a liquid from a treatmend liquid source C1 to Cn can flow successively through the inlet / outlet port 424, the converging hole 423, the plurality of channels 414, the through hole 405 and the longitudinal passage 7 between the anode 3 and the barrel T.

[0068] Referring to FIGS. 4 and 5, it can be seen that the second interface assembly 4B comprises a second module 40B, made of electrically insulating material, a second module 41B, made of electrically conductive material, and a second conical sealed connection module 42B.

[0069] The second insulating module 40B is analogous to the first insulating module 40A and is screw-fastened to the second end E2 of the barrel T. In particular, the internal threads 404 provided in the hexagonal external profile section 401, and referred to as first threaded bore, cooperate with the external threads T2 of the second end region E2 of the barrel T.

[0070] The second module 41B, made of electrically conductive material, is analogous to the first electrically conductive module 41A, except that it has a radial hole 415 at the annular section 411 in contact with the annular section 403, which hole 415 is configured to receive the connection element 30 for electrical connection of the anode 3 to the current source 8. The region of the second end of the anode 3 passes through the cylindrical hole 412 and the threaded bore 413, the external thread 31 of the anode 3 engaging the thread of the threaded bore 413 referred to as the second threaded bore. The thread pitch of this second threaded bore 413 is reversed with respect to the thread pitch of the first threaded bore 404. In this way, when the anode 3 is positioned relative to the barrel T, with the first end of the anode 3 held rotationally fixed by the rotation lock at the hexagonal profile section 401, screwing the second insulating module 40B along the second end E2 of the gun barrel T causes the second end of the anode 3 to be screwed into the second electrically conductive module 41B, i.e. away from the first end of the anode 3. The threaded bores 404, 413 of the sealed interface means 4A, 4B thus constitute the means for putting the anode 3 under traction.

[0071] The second conical module 42B is analogous to the first conical module 42A.

[0072] The means 5 for driving the gun barrel T in rotation serve to enable axial rotation of the barrel T, in other words, rotation of the barrel T about its longitudinal axis X0. In the preferred embodiment of the invention, these means 5 enable the barrel T to rotate axially through 360 degrees in a first direction of rotation and then axially through 360 degrees in a second, opposite direction of rotation, alternately.

[0073] As can be seen in FIG. 3, these driving means 5 may comprise a control means, in particular a motor 50 carried by the upper longitudinal members of the chassis assembly 1, and transmission means. The transmission means comprise a connecting rod 51 coupled to the output shaft of the motor 50 and connected to a rack 52 of a rack-and-pinion system. Thus, rotation of motor 50 causes the rack 52 to move in translation alternately in a first direction and in a second direction. The translational movement of the rack 52 then causes the associated pinion 53 to rotate in one direction or the other. This pinion 53 is coupled to a pulley-belt assembly, one pulley 54 of which is mounted on a shaft coupled to the pinion 53, and the other pulley 55 of which is mounted on a first shaft of a roller assembly 57. Thus, rotation of pinion 53 drives rotation of the pulleys 54, 55, via the belt 56, and thus rotation of the first shaft carrying the roller assembly 57. The roller assembly 57 comprises a first pair of rollers mounted on the first shaft and a second pair of rollers mounted on a second shaft, the second shaft being coupled to the first shaft by another pulley-belt assembly 58. The first and second shafts parallel to each other and to the longitudinal axis X0. The two pairs of rollers 57 are arranged on either side of the longitudinal axis X0 and below the gun barrel T so as to support the barrel T from below and communicate the rotational movement of the rollers 57 to the gun barrel T. The roller assembly 57 is supported by upper longitudinal members of the frame assembly 1, at one of the longitudinal end regions of the frame assembly 1. At the other longitudinal end region of frame assembly 1, a pair of rollers 59 are mounted so as to rotate freely about axes of rotation parallel to each other and to the longitudinal axis X0. These rollers 59 support the gun barrel T via a rolling ring assembly 60, which may be used to compensate for any conicity of the gun barrel T. The rolling ring assembly 60 is mounted around the gun barrel T and is traversed by the rod 20 of the cathode 2. Thus, the assembly comprising the gun barrel T, the cathode 2, the anode 3 and the sealed interface means 4A, 4B, is able to rotate when the gun barrel T is rotated about its longitudinal axis X0.

[0074] Referring now to FIG. 8, it can be seen that for the implementation of a surface treatment, the device D according to the present invention is integrated into a surface treatment system S, in particular a system operating in a closed circuit. The system S according to the present invention comprises an electrical circuit CE and a hydraulic circuit CH connected to the device D described above.

[0075] The electrical circuit CE comprises a current source 8 and electrical cables 9 connecting, on the one hand, the positive pole (+) of the current source 8 and the anode 3 by passing current through the connection element 30 received in the second electrically conductive module 41B, and on the other hand, the negative pole (−) of the current source 8 and the cathode 2 by passing current through the connection element 23 received in the connector module 22.

[0076] The hydraulic circuit CH comprises a plurality of treatment liquid storage tanks C1 to Cn constituting the at least one source of treatment liquid. Each tank C1 to Cn is associated with at least one upstream pipe 14 fitted with a solenoid valve 15, which is connected to control means 16 including in particular a man-machine interface, an automatic control system with probes, and sensors. Treatment liquid circulation means, such as pumps, enable liquid circulation through the upstream pipes 14. Downstream pipes 17 connected to the upstream pipes 14 are in fluid communication with the inlet / outlet ports 424 of the first 42A and second 42B conical modules to enable a treatment liquid to circulate between one of the tanks C1 to Cn and the longitudinal passage 7. Liquid circulation in the downstream pipes 17 is controlled by alternating circulation means 18 capable of circulating one of the treatment liquids through the longitudinal passage 7 alternately in a first circulation direction and in a second circulation direction (two-way arrows in FIG. 8). Thus, treatment liquid enters the passage 7 through the first end E1 of barrel T and exits the passage 7 through the second end E2 of barrel T, then after a certain predetermined time, treatment liquid enters the passage 7 through the second end E2 of barrel T and exits the passage through the first end E1 of barrel T. In FIG. 8, the alternating circulation means 18 are shown as a reversible circulation pump driven by a drive motor capable of rotating in both directions.

[0077] In operation, the method implementing the system S according to the invention comprises the following preliminary steps:

[0078] mounting the cathode 2 on the gun barrel T by means of the two connecting flanges 21;

[0079] mounting the rolling ring assembly 60 around the barrel T and the cathode 2;

[0080] mounting the connector module 22 around the first insulating module 40A;

[0081] securing the first insulating module 40A on the first end E1 of the barrel T and securing the second insulating module 40B on the second end E2 of the barrel T. To do this, for each insulating module 40A, 40B, a wrench corresponding to the hexagonal profile 401 is used to screw the module 40A, 40B onto the threads T1, T2;

[0082] securing the second electrically conductive module 41B to the second insulating module 40B;

[0083] inserting the anode 3 into the barrel T by inserting the anode 3 from the first insulating module 40A, until the threads 31 of the second end of the anode 3 engage with the threaded bore 413 of the second electrically conductive module 41B;

[0084] securing the first electrically conductive module 41A to the first end of the anode 3 by screwing the reinforcing rod 33 into the threaded bore 413, then securing the first electrically conductive module 41A to the first insulating module 40A;

[0085] putting the anode 3 under traction. To do this, a first operator holds the first insulating module 40A in position relative to the barrel T, using a wrench corresponding to the hexagonal profile 401, so that the first insulating module 40A and therefore the first electrically conductive module 41A and the anode 3 are locked against rotation. A second operator screws the second insulating module 40B onto the barrel T using a corresponding wrench and applies a tightening torque, in particular 130 dN·m. Due to the inverted thread pitches of the threaded bores 404, 413, this screwing allows the anode 3 to be put under traction between the two electrically conductive modules 41A, 41B;

[0086] placing the gun barrel T on the means 5 for driving in rotation, which are carried by the frame assembly 1. To that end, the rolling ring assembly 60 is placed on the pair of rollers 59 mounted free to rotate, and a region of the barrel T located between the cathode 2 and the second interface assembly 4B is placed on the pairs of rollers 57 driven in rotation by the motor 50;

[0087] securing the first and second conical modules 42A, 42B to the first and second electrically conductive modules 41A, 41B respectively;

[0088] where necessary, particularly in the case of a barrel T of great length, mounting the brackets 12 on the support frame 10 and suspending the electrical cables 9 and hydraulic lines 17 from these brackets 12.

[0089] Once these preliminary steps have been completed, the barrel T to be treated can act as a cathode and is positioned in the desired non-vertical position, in particular horizontally, and the anode 3 is held strictly coaxial with the longitudinal axis X0 of the barrel T.

[0090] The electrochemical treatment method may then comprise the following treatment steps:

[0091] connecting the conical modules 42A, 42B to the hydraulic circuit CH;

[0092] connecting the current source 8 to the cathode 2 by mounting the connector module 22 around the first insulating module 40A and around the rod 20, and connecting the connector element 23 to the negative pole (−), and to the anode 3 by connecting the connection element 30 of the second electrically conductive module 41B to the positive pole (+);

[0093] inserting an electrolyte into the longitudinal passage 7 by actuating the circulation means and controlling the control means 16;

[0094] once the surface temperature of the barrel T has homogenized, switching on the current source 8. The passage of an electric current in the treatment liquid flowing in the longitudinal passage 7 enables the surface treatment of the inner wall Pi of the barrel T;

[0095] during the surface treatment, actuating the alternating circulation means 18 for the treatment liquid and the means 5 for driving the barrel T in rotation. In this way, the barrel T is rotated about its longitudinal axis X0 in alternating directions of rotation, and treatment liquid flows through the barrel T in one longitudinal direction and then in the other.

[0096] Once the surface treatment is complete, the circulation of treatment liquid is stopped, the barrel T is drained, the interface assemblies 4A, 4B are disassembled and the device D is disconnected from the electrical circuit CE and the hydraulic circuit CH.

[0097] It is therefore understood that the system S according to the present invention enables a sequence of surface treatments to be implemented. For example, the system S can implement a cleaning of the inner surface of the barrel B so as to condition subsequent adhesion of a deposit, an electrolytic chromium plating to deposit a chromium layer, one or more rinses, an electropolishing, etc., depending on the desired treatment, the control means 16 of the hydraulic circuit CH control the fluidic connection between the tank C1 to Cn containing the appropriate treatment liquid and the device D. For example, for a cleaning, the device D according to the invention is traversed by an etching liquid (acidic, basic, etc.), whereas for a chromium plating, the device D is traversed by a chromium-based liquid. Thus, the number of storage tanks C1 to Cn and the treatment liquids contained in these tanks are adapted to the desired surface treatments. In addition, current is circulated in the electrical circuit CE only when the treatment to be carried out is electrochemical.

[0098] It is understood that the particular embodiments just described are indicative and non-limiting, and that modifications may be made without departing from the scope of the present invention.

Claims

1. A device for electrochemical surface treatment of an inner surface of a longitudinal tubular member made of electrically conductive material, the tubular member having a longitudinal axis and being open at first and second ends, which device comprises:a frame assembly configured to support such a tubular member so as to allow the tubular member to rotate about the longitudinal axis;at least one cathode intended to be connected to a negative pole of a current source and configured to be electrically connected to the tubular member;a longitudinal anode intended to be connected to a positive pole of the current source and configured to be positioned inside the tubular member, coaxially with the longitudinal axis and at least along the entire length of the tubular member;sealed interface means configured to removably cooperate with the tubular member at first and second ends of the tubular member and to seal said first and second ends, ends, and to cooperate with the anode to ensure that it is centered relative to the tubular member, the sealed interface means comprising at least one first inlet / outlet port adapted to communicate with the first open end of the tubular member and at least one second inlet / outlet port adapted to communicate with the second open end of the tubular member, so that, in use, a sealed longitudinal passage is formed between the anode and the inner surface of the tubular member from the first to the second end of the tubular member, the inlet / outlet ports being intended to be connected to a source of treatment liquid; andmeans for driving the tubular member in rotation about the longitudinal axis,wherein the frame assembly is adapted to support the tubular member in a non-vertical orientation of the tubular member and the device further comprises means for putting the anode under traction, configured to, when the anode is mounted within the tubular member, act on at least one of the two ends of the anode to prevent deflection of the anode.

2. The device-according to claim 1, wherein the means for putting the anode under traction are configured to allow traction adjustment by screwing the anode onto one of the sealed interface means.

3. The device according to claim 2, wherein the means for putting the anode under traction comprise at least one first threaded bore and at least one second threaded bore provided in the sealed interface means, one of the at least one first threaded bore being configured to cooperate with one of the ends of the tubular member, and one of the at least one second threaded bores being configured to cooperate with an external thread provided on the corresponding end region of the anode, the at least one first threaded bore having a thread pitch reversed with respect to a thread pitch of the at least one second threaded bore, so that, in use, when the at least one first threaded bore is screwed onto the end of the tubular member and the other end of the anode is held stationary, the end region of the anode carrying the external thread is caused to screw into the at least one second threaded bore.

4. The device according to claim 1, wherein the sealed interface means comprise a first and a second interface assembly, the first interface assembly comprising a first module made of electrically insulating material, configured to cooperate with the first end of the tubular member and to be traversed by the anode, and a first module made of electrically conductive material, secured to the first module made of electrically insulating material and configured to cooperate with the first end of the anode, the second interface assembly comprising a second module made of electrically insulating material, configured to cooperate with the second end of the tubular member and to be traversed by the anode, and a second module made of electrically conductive material, secured to the second module made of electrically insulating material and connected to the second end of the anode via the means for putting the anode under traction.

5. The device according to claim 1, wherein the at least one cathode is a peripheral cathode comprising a metal rod intended to be positioned outside the tubular member and along a generatrix of the tubular member, the rod carrying at least one flange for connection to the tubular member and a connector module for connecting the rod to the current source, the connector module being secured to the sealed interface means while being in electrical isolation from the anode, so that in use the tubular member takes on the function of cathode.

6. The device according to claim 1, wherein the frame assembly comprises a support frame and a mobile frame mounted on the support frame and movable relative to the support frame, at least pivotally about a pivot axis, the means for driving the tubular member in rotation being secured to the mobile frame, an amplitude of pivoting of the mobile frame about the pivot axis allowing, in use, the tubular member to be at an angle of inclination, relative to a horizontal plane, comprised between 0 and 90 degrees inclusive.

7. The device according toclaim 1, wherein the means for driving the tubular member in rotation are configured to produce an alternating rotational movement of the tubular member, so that, in use, the tubular member is able to be rotated, over a given angular range, alternately in a given direction of rotation and then in an opposite direction of rotation.

8. A system for electrochemical surface treatment of an inner surface of a tubular member made of electrically conductive material, wherein the system comprises a device according to claim 1, which system further comprises:an electrical circuit comprising a current source a positive pole of which is connected to the anode and a negative pole of which is connected to the at least one cathode;a hydraulic circuit connected to the first and second inlet / outlet ports of the device and comprising at least one source of treatment liquid and means for circulating treatment, which hydraulic circuit further comprises alternating circulation means capable of circulating the treatment liquid in the longitudinal passage, in a first step from the first toward the second end, and then in a second step inversely from the second toward the first end.

9. The system according to claim 8, wherein the anode is connected to the current source via a first conductive connection element connected on the one hand to the positive pole of the current source and on the other hand to the second module made of electrically conductive material, and wherein the cathode is connected to the current source via a second conductive connection element connected on the one hand to the negative pole of the current source and on the other hand to the connector module.

10. The system according to claim 8, wherein the hydraulic circuit comprises a plurality of treatment liquid storage tanks, each tank being associated with at least one pipe for the delivery of the liquid it contains, which pipe is equipped with a solenoid valve, control means being provided to control the solenoid valves and enable one of the storage tanks to be fluidly connected to the device.

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