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

Abstract

The invention relates to a device (D) and a system for electrochemical surface treatment of an inner surface of a longitudinal tubular element (T) made of electrically conductive material, the device (D) comprising: a frame assembly (1); at least one cathode (2) configured to be electrically connected to the tubular element (T); a longitudinal anode configured to be placed coaxially inside the tubular element (T); means (4A, 4B) forming a sealed interface configured to removably cooperate with the tubular element (T) and with the anode, the means (4A, 4B) forming a sealed interface comprising at least first and second inlet / outlet ports intended to be connected to a source of treatment liquid and capable of communicating, when in use, with a sealed longitudinal passage that is formed between the anode and the inner surface of the tubular element (T); and means (5) for rotating the tubular element (T) about its longitudinal axis (X0), characterised in that the frame assembly (1) is capable of supporting the tubular element (T) in a non-vertical orientation and in that the device (D) further comprises means for pulling the anode that are configured to act on at least one of the two ends of the anode in order to prevent the anode from bending.

Description

Device for the electrochemical surface treatment of an interior surface of a tubular element made of electrically conductive material, in particular a weapon tube, and system comprising such a device

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

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

[0003] In the field of weaponry, 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 resistance of the gun barrel 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 lifetime. Indeed, chromium has a significant hardness and a low chemical interaction with other metals, these two properties combined considerably limiting the wear of the parts. Chromium plating also has the advantage of adding a corrosion-resistant coating to the gun barrel, which increases the lifetime of the gun barrel, particularly in humid environments.

[0004] This chromium layer is usually applied electrolytically. For this purpose, an anode is introduced 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 in the gun barrel, between the anode and the inner wall of the gun barrel, while a voltage is applied to the anode and the gun barrel. The electric current flowing from the anode to the gun barrel via the electrolyte causes a thin layer of chromium to be deposited on the inner surface of the gun barrel.

[0005] Patent GB712314, published on 21 / 07 / 1954, discloses such a method of electrolytically chromium plating the inner surface of a gun barrel, as well as an apparatus for carrying out this method. In order to obtain a regular deposit, the gun barrel is positioned vertically and is rotated around its longitudinal axis.

[0006] This solution is suitable for light or medium-caliber weapon barrels. However, due to the vertical positioning of the weapon barrel, this solution has disadvantages when applied to large-caliber weapon barrels several meters long, since it requires a very high height and suitable handling equipment.

[0007] The present invention thus aims to propose a solution allowing the electrochemical surface treatment, in particular electrolytic chrome plating, of the interior surface of a tubular element made of electrically conductive material, in particular a large-calibre weapon barrel, in a space having a reduced height volume, while ensuring the most constant possible distribution of a metal deposit in thickness in the case of a metal coating.

[0008] The solution according to the present invention is based on the use of a device for orienting the tubular element in a non-vertical orientation, such as horizontally, and further comprising both means for applying traction to the anode and means for driving the tubular element in rotation about its longitudinal axis. The means for applying traction to the anode make it possible to give the anode the greatest possible straightness and to keep it strictly coaxial with the tubular element so that it remains equidistant from the inner wall of the tubular element, thus avoiding its bending. The means for driving the tubular element in axial rotation make it possible to prevent gases, particularly those resulting from electrolysis, from accumulating at a given point on the tubular element, a point which would then receive a smaller deposit of metal in the case of a metal coating.Together, the means for applying traction to the anode and the means for driving the tubular element in axial rotation make it possible to prevent the occurrence of a phenomenon of shrinkage of the internal diameter of the tubular element, of the “hourglass effect” type, in which the metal deposit has a profile comparable to that of an hourglass.

[0009] The solution according to the present invention is also based 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 element in both directions, in an alternating manner. In the case of a metal coating, the alternating circulation means make it possible to ultimately obtain a metal coating which has been deposited with the same metal deposition speed over the entire length of the tubular element, even at its two ends, and thus to prevent the deposition from taking place more quickly at one end than at another, which would lead to giving the inner surface of the tubular element a blunderbuss shape.

[0010] The present invention therefore relates to a device for the electrochemical surface treatment of an inner surface of a longitudinal tubular element made of an electrically conductive material, in particular for the electrolytic metallic coating of an inner wall of a weapon barrel, the tubular element having a longitudinal axis and being open at first and second ends, which device comprises: - a frame assembly configured to support such a tubular element so as to allow the tubular element to rotate around its longitudinal axis; - 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 element; - a longitudinal anode intended to be connected to the positive pole of the current source and configured to be placed inside the tubular element,coaxially with the longitudinal axis and at least over the entire length of the tubular element;- means forming a sealed interface configured to cooperate removably with the tubular element at the first and second ends of the tubular element and to ensure the sealing of said first and second ends, and to cooperate with the anode in order to ensure its centering relative to the tubular element, the means forming a sealed interface comprising at least a first inlet and outlet orifice (or "inlet / outlet orifice") capable of communicating with the first open end of the tubular element and at least a second inlet and outlet orifice (or "inlet / outlet orifice") capable of communicating with the second open end of the tubular element, such that in use,a sealed longitudinal passage is formed between the anode and the inner surface of the tubular element from the first to the second end of the tubular element, the inlet and outlet ports being intended to be connected to a source of treatment liquid; and- means for driving the tubular element in rotation about its longitudinal axis,characterized by the fact that the frame assembly is capable of supporting the tubular element in a non-vertical orientation of the latter and that the device further comprises means for applying traction to the anode configured to, when the anode is mounted inside the tubular element, act on at least one of the two ends of the anode in order to prevent bending of the anode.,

[0011] Thanks to the presence of both means for applying traction to the anode and means for driving the tubular element in axial rotation, it can be seen that the appearance of an "hourglass" effect can be avoided during a metal deposition operation using the device according to the invention. In addition, it turns out that the presence of means for applying traction to the anode makes it possible, in use, to obtain a satisfactory surface treatment even when positioning the tubular element horizontally on the chassis assembly, even in the case of a very long tubular element. It is then possible to use the device according to the invention in a workshop with reduced height volumes.

[0012] The device according to the invention may be a chrome plating device, the source of treatment liquid then being a chrome plating bath, in particular a chromic acid bath.

[0013] Preferably, the anode comprises a cylindrical rod formed from a single piece of conductive metal, in particular copper, and at each end, a lead sheath brazed to the rod. Such a lead sheath makes it possible to improve the corrosion resistance of the anode and to enable it to have sufficient mechanical strength over time.

[0014] Preferably, the rotation drive means comprise means for controlling the direction and / or speed of rotation.

[0015] In a particular embodiment, the means for driving the tubular element in rotation are configured to produce an alternating rotational movement of the tubular element, so that in use, the tubular element is able to be rotated, over a determined angular range, alternately in a given direction of rotation, then in the opposite direction of rotation.

[0016] Advantageously, the rotational drive means 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 element around its longitudinal axis.

[0017] In a particular embodiment, the rotational drive means comprise a rack and pinion system, the rack of which is coupled to a motor via a connecting rod and the pinion of which is coupled to a pulley-belt assembly, which pulley-belt assembly is connected to a roller assembly intended to support the tubular element and the rollers of which are mounted to rotate about axes intended to be parallel to the longitudinal axis of the tubular element. At least some of the rollers are driven in rotation by the pulley-belt assembly, so as to themselves rotate the tubular element.

[0018] Advantageously, the anode traction means are configured to allow adjustment of the traction by screwing the anode onto one of the means forming a sealed interface. Such anode traction, by mechanical tightening, is more reliable than spring traction.

[0019] Preferably, in use, the tightening torque applied to put the anode under tension is of the order of 130 dN.m.

[0020] In a particular embodiment, the means for applying traction to the anode comprise at least one first threaded bore and at least one second threaded bore provided in the means forming a sealed interface, the or one of the first threaded bores being configured to cooperate with one of the ends of the tubular element, 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 screw pitch that is reversed relative to the screw pitch of said second threaded bore, such that in use, when said first threaded bore is screwed onto the end of the tubular element and the other end of the anode is held fixed, the end region of the anode carrying the external thread is caused to screw into said second threaded bore.

[0021] Advantageously, a reinforcing rod is provided for the removable attachment of the anode to the sealing interface means at the end region of the anode opposite the end region carrying the external thread, the rod having a first and a second external thread which cooperate, respectively, with a third threaded bore of the sealing interface means and a threaded axial orifice of the anode. Such a rod makes it possible to increase the strength at the attachment zone.

[0022] Preferably, the threaded axial hole is provided in the first end region of the anode, and the external thread is provided on the second end region of the anode.

[0023] Advantageously, the means forming a sealed interface comprise, at the level of the or each first tapped bore, a hexagonal external profile made of electrically insulating material. Such a hexagonal profile is suitable for cooperating with a conventional tool, in particular a key capable of ensuring rotational locking or tightening, having a corresponding hexagonal profile.

[0024] In a particular embodiment, the sealed interface forming means comprise a first and a second interface forming assembly, the first interface forming assembly comprising a first module made of electrically insulating material configured to cooperate with the first end of the tubular element and to be crossed by the anode and a first module made of electrically conductive material fixed to the first module made of electrically insulating material and configured to cooperate with the first end of the anode, the second interface forming assembly comprising a second module made of electrically insulating material configured to cooperate with the second end of the tubular element and to be crossed by the anode and a second module made of electrically conductive material fixed to the second module made of electrically insulating material and connected to the second end of the anode via the anode traction means.

[0025] 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.

[0026] Preferably, a conical sealed connection module made of an electrically insulating material and intended to be connected to a source of treatment liquid is fixed to each module made of electrically conductive material, each conical module comprising a convergent orifice in communication with the inlet / outlet orifice(s) of the means forming a sealed interface. Such a conical module makes it possible to avoid turbulence and to maintain a laminar flow.

[0027] Preferably, the at least one cathode is a peripheral cathode comprising a metal rod intended to be positioned outside the tubular element and along a generatrix thereof, the rod carrying at least one flange for connection to the tubular element and a connector module intended to connect the rod to the current source, the connector module being fixed to the means forming a sealed interface while being electrically insulated from the anode, such that in use, the tubular element takes on the function of cathode.

[0028] Preferably, the modules are fixed together by removable fixing members, in particular bolts.

[0029] In a particular embodiment, the chassis assembly comprises a supporting chassis and a mobile chassis mounted on the supporting chassis and mobile relative to the supporting chassis, at least pivoting about a pivot axis, the means for driving the tubular element in rotation being integral with the mobile chassis, the amplitude of the pivoting of the mobile chassis about the pivot axis allowing, in use, the tubular element to form an angle of inclination relative to a horizontal plane of between 0 and 90 degrees inclusive.

[0030] Preferably, at least one actuator of the linear cylinder type is connected between the supporting frame and the mobile frame, one end of the actuator being articulated to the mobile frame around an axis of rotation parallel to the pivot axis and eccentric relative to the pivot axis.

[0031] Preferably, the supporting chassis is a rolling chassis, for example equipped with at least a first wheel set and a second wheel set.

[0032] The present invention also relates to a system for the electrochemical surface treatment of an interior surface of a tubular element made of electrically conductive material, characterized in that it comprises a device as defined above, which system further comprises:- 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- 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, initially from the first to the second end, then in a second step inversely from the second to the first end.

[0033] Thanks to the presence of both means for applying traction to the anode, means for driving the tubular element in axial rotation, and means for alternating circulation of a treatment liquid, it can be seen that the appearance of a "blunderbuss" phenomenon can be avoided during a metal deposition operation using the system according to the invention.

[0034] The alternating circulation means may comprise a reversible circulation pump driven by a drive motor capable of rotating in both directions of rotation.

[0035] 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 by the fact that 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.

[0036] Advantageously, the circulation speed of the treatment liquid is between 0.1 and 5 m / s and the applied current density is 20 to 60 A / dm².

[0037] Preferably, the hydraulic circuit comprises a plurality of treatment liquid storage tanks, each tank being associated with at least one conduit for delivering the liquid it contains, which conduit is equipped with a solenoid valve, control means being provided for controlling the solenoid valves and enabling one of the storage tanks to be fluidically connected to the device.

[0038] 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.

[0039] To better illustrate the object of the present invention, a particular embodiment thereof will be described below, with reference to the attached drawings. In these drawings:

[0040] is a side view of the device according to a particular embodiment of the invention, a weapon tube being supported horizontally;

[0041] is a perspective view of the device, with jibs being added on either side of the supporting frame;

[0042] is an enlarged perspective view of the rotary drive means, with a portion of the frame assembly and a section of the tube omitted for clarity;

[0043] is an enlarged perspective view of the device at a first end of the tubular member;

[0044] is a longitudinal sectional view of the enlarged region of the;

[0045] is an enlarged perspective view of the device at a second end of the tubular member;

[0046] is a longitudinal sectional view of the enlarged region of the ; and

[0047] represents a diagram of the system according to the present invention.

[0048] Referring first to Figures 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 "tube" is therefore used to designate the element to which the device D is applied. However, the application of the device D according to the invention is not limited to gun barrels T, the element being able to be any longitudinal tubular element made of electrically conductive material, including a very long tubular element.

[0049] As can be seen in Figures 1 and 2, the device D according to the invention comprises at least one chassis assembly 1, a cathode 2, an anode 3, means forming a sealed interface 4A, 4B, means for driving the weapon tube T in rotation 5, and means for applying traction 6 to the anode 3.

[0050] The chassis assembly 1 has the function of supporting the weapon tube T to be processed in a non-vertical orientation of the weapon tube T.

[0051] In the particular embodiment shown, the chassis assembly 1 comprises a supporting chassis 10 configured to support the tube T horizontally while allowing it to rotate around its longitudinal axis X0. For this purpose, the supporting chassis 10 carries the rotational drive means 5 of the tube T. The supporting chassis 10 is a mechanically welded chassis, on braked rollers 11, comprising longitudinal side members connected by crosspieces. As can be seen in the, brackets 12 may be provided at each longitudinal end of the supporting chassis 10, in order to allow the suspension of electrical cables 9 and liquid pipes 17 intended to be connected to the device D. Similarly, a pair of glasses 13 forming frames arranged in vertical planes and capable of being crossed by the weapon tube T, may be mounted on the upper side members of the supporting chassis 10.The upper side members and the glasses 13 being configured such that the longitudinal position of the glasses 13 on the supporting frame 10 is adjustable, thus adapting to the length of the part to be treated.

[0052] Alternatively, the chassis assembly 1 could also comprise a movable chassis (not shown) mounted on the supporting chassis 10 and carrying the means 5 for driving the tube T in rotation. For example, the movable chassis could be mounted so as to pivot relative to the supporting chassis 10 about a horizontal pivot axis orthogonal to the longitudinal axis of the supporting chassis 10. The pivoting movement of the movable chassis about the pivot axis could be controlled by a jack connected to the supporting chassis 10 and articulated to the movable chassis about a rotation axis parallel to the pivot axis. Thus, in use, an extension of the rod of the jack causes a movement of the movable chassis and therefore of the weapon tube T that it supports to a high position, for example a position in which the longitudinal axis X0 of the weapon tube is horizontal.Conversely, a retraction of the cylinder rod causes a displacement of the movable frame and therefore of the weapon tube T to a low position in which the longitudinal axis X0 of the weapon tube T forms an angle of between 0 and 90 degrees with respect to a horizontal plane. It should be emphasized that the cylinder could be replaced by any other suitable linear actuator. Thus, such a frame assembly makes it possible to position the weapon tube T at any desired angle of inclination. In order to ensure that the tube is maintained in axial position relative to the movable frame, in particular in the case where the angle of inclination is significant, an anti-slip ring is mounted around the tube and abuts against a stop-forming element of the movable frame.

[0053] The cathode 2, once connected to the negative pole (-) of a current source 8, allows the weapon tube T to take on the function of cathode. As can be seen in Figures 1, 2, 6 and 7, the cathode 2 comprises an attached metal rod 20 positioned along the tube T, outside the latter, and connected to the tube T by electrically conductive connecting flanges 21 fitting around the tube 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 made of electrically insulating material 40A 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 energized, the current flows in an electrical circuit CE to the connection element 23, then flows successively in the connector module 22, in the rod 20, in the flanges 21 and in the wall of the tube T.

[0054] The anode 3 is a longitudinal cylindrical part made of conductive metal, in particular copper and lead. As can be seen in Figures 5 and 7, in the assembled state, the anode 3 is centered coaxially with the gun barrel T and projects 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 to the other of the barrel T. Thus, the diameter of the anode 3 is a function of the surface treatment to be applied, for example, the desired metal deposit thickness, and the dimensions of the barrel T.

[0055] As can be seen in the, the anode 3 is connected to the positive pole (+) of a current source 8 via a module made of electrically conductive material 41B of the sealed interface means 4B. This module 41B receives 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 comprises an external thread 31 which engages with a tapped bore 413 of the module 41B. Thus, once the current source 8 is energized, the current flows in an electrical circuit CE to the connection element 30, then flows in the electrically conductive module 41B and in the anode 3. As can be seen in the, the other end region of the anode 3 comprises a threaded axial orifice 32. A reinforcing rod 33 makes it possible to fix the anode 3, by its threaded end, to another electrically conductive module 41A of the means forming a sealed interface 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 orifice 32 of the anode 3.

[0056] The sealed interface means 4A, 4B have the function of closing the weapon tube T at each of its two open ends E1, E2, of maintaining the anode 3 in position in the tube T and of allowing a fluid connection between a source of treatment liquid C1 and C n and the longitudinal passage 7 formed inside the tube T. The sealed interface forming means 4A, 4B comprise first 4A and second 4B interface forming assembly cooperating, respectively, with the first E1 and second E2 ends of the weapon tube T and of the anode 3.

[0057] Referring to Figures 6 and 7, it can be seen that the first interface assembly 4A comprises a first module made of electrically insulating material 40A, a first module made of electrically conductive material 41A and a first conical sealed connection module 42A.

[0058] The first module made of electrically insulating material 40A 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 comprises internal threads 404 which cooperate with external threads T1 carried by the first end region E1 of the tube T. Thus, this insulating module 40A is fixed by screwing to the first end E1 of the tube T. The cylindrical section 402 is dimensioned such that the connector module 22 is adapted around it. The through-orifice 405 of this insulating module 40A is arranged coaxially with the longitudinal axis X0 of the tube T and of the anode 3 so as to open into the tube T.The annular section 403 has an external diameter greater than the external diameter of the cylindrical section 402, so as to allow the assembly of this module 40A with the first electrically conductive module 41A by removable fixing members, in particular bolts 43.

[0059] The first module made of electrically conductive material 41A is a tubular body made for example of steel and having a cylindrical section 410 interposed in two annular sections 411. The cylindrical section 410 comprises a cylindrical orifice 412 in which the first end region of the anode 3 is placed. The cylindrical orifice 412 is coaxial with the longitudinal axis X0. This section 410 therefore allows the positioning, in particular the centering, of the anode 3 relative to the tube T. The threaded bore 413 engaged with the reinforcing rod 33 opens into this cylindrical orifice 412. Thus, the anode 3 is fixed, by its first end, 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 assembled in a sealed manner by means of bolts 43, rings and seals. A plurality of cylindrical channels 414 are arranged around the orifice 412 coaxial with the weapon tube T. These channels 414 open on the one hand into the through orifice 405 of the first insulating module 40A and on the other hand into a convergent orifice 423 of the first conical module 42A.

[0060] 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 attachment to the first electrically conductive module 41A, a conical section 421 and a cylindrical section 422. The converging orifice 423 is formed in the conical section 421. A cylindrical inlet / outlet orifice 424 is formed in the cylindrical section 422. The converging orifice 423 opens into the cylindrical inlet / outlet orifice 424. Thus, a liquid from a treatment liquid source C1 to C n can circulate successively through the inlet / outlet orifice 424, the converging orifice 423, the plurality of channels 414, the through orifice 405 and the longitudinal passage 7 between the anode 3 and the tube T.

[0061] Referring to Figures 4 and 5, it can be seen that the second interface assembly 4B comprises a second electrically insulating material module 40B, a second electrically conductive material module 41B and a second conical sealed connection module 42B.

[0062] The second insulating module 40B is similar to the first insulating module 40A and is fixed by screwing to the second end E2 of the tube T. In particular, the internal threads 404 provided in the section with hexagonal external profile 401, and designated by first tapped bore, cooperate with the external threads T2 of the second end region E2 of the tube T.

[0063] The second module of electrically conductive material 41B is similar to the first electrically conductive module 41A, except that it has a radial orifice 415 at the annular section 411 in contact with the annular section 403, which orifice 415 is configured to receive the connection element 30 for the electrical connection of the anode 3 to the current source 8. The second end region of the anode 3 passes through the cylindrical orifice 412 and the tapped bore 413, the external thread 31 of the anode 3 engaging the thread of the tapped bore 413 designated as the second tapped bore. The thread pitch of this second tapped bore 413 is reversed with respect to the thread pitch of the first tapped bore 404.Thus, when positioning the anode 3 relative to the tube T, the first end of the anode 3 being held fixed in rotation by the rotation lock at the level of the hexagonal profile section 401, screwing the second insulating module 40B along the second end E2 of the weapon tube T causes screwing of the second end of the anode 3 into the second electrically conductive module 41B, therefore opposite the first end of the anode 3. The tapped bores 404, 413 of the means forming a sealed interface 4A, 4B therefore constitute the means for applying traction to the anode 3.

[0064] The second conical module 42B is analogous to the first conical module 42A.

[0065] The rotation drive means 5 of the weapon tube T have the function of allowing the axial rotation of the tube T, in other words the rotation of the tube T around its longitudinal axis X0. In the preferred embodiment of the invention, these means 5 allow the tube T to perform an axial rotation through 360 degrees in a first direction of rotation then an axial rotation through 360 degrees in a second opposite direction of rotation, alternately.

[0066] As can be seen in the, these drive means 5 may comprise a control means, in particular a motor 50 carried by the upper side 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, a rotation of the motor 50 causes a translational movement of the rack 52 alternately in a first direction and in a second direction. The translational movement of the rack 52 then causes the rotation of the associated pinion 53 in one direction of rotation or the other. This pinion 53 is coupled to a pulley-belt assembly, one of the pulleys 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, the rotation of the pinion 53 drives the rotation of the pulleys 54, 55, via the belt 56, and therefore the 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 are parallel to each other and parallel to the longitudinal axis X0. The two pairs of rollers 57 are arranged on either side of the longitudinal axis X0 and below the weapon tube T so as to support the tube T from below and to communicate the rotational movement of the rollers 57 to the weapon tube T. The roller assembly 57 is supported by upper side members of the chassis assembly 1, at one of the longitudinal end regions of the chassis assembly 1.At the other longitudinal end region of the chassis assembly 1, a pair of rollers 59 are provided, mounted free to rotate about axes of rotation parallel to each other and parallel to the longitudinal axis X0. These rollers 59 support the weapon tube T by means of a bearing ring assembly 60, which, if necessary, makes it possible to compensate for any conicity of the weapon tube T. The bearing ring assembly 60 is mounted around the weapon tube T and is traversed by the rod 20 of the cathode 2. Thus, the assembly comprising the weapon tube T, the cathode 2, the anode 3 and the means forming a sealed interface 4A, 4B is able to rotate when the weapon tube T is rotated about its longitudinal axis X0.

[0067] If we now refer to the, we can see 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.

[0068] 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 the 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 the current through the connection element 23 received in the connector module 22.

[0069] The hydraulic circuit CH comprises a plurality of tanks C1 to C nof treatment liquid storage constituting at least one source of treatment liquid. Each tank C1 to C n is associated with at least one upstream conduit 14 equipped with a solenoid valve 15, which is connected to control means 16 comprising in particular a human-machine interface, an automaton with probes and sensors. Means for circulating treatment liquid, such as pumps, allow the liquid to be circulated through the upstream conduits 14. Downstream conduits 17 connected to the upstream conduits 14 are in fluid communication with the inlet / outlet orifices 424 of the first 42A and second 42B conical modules in order to allow the circulation of a treatment liquid between one of the tanks C1 to C nand the longitudinal passage 7. The circulation of the liquid in the downstream conduits 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 on the). Thus, treatment liquid enters the passage 7 through the first end E1 of the tube T and leaves the passage 7 through the second end E2 of the tube T, then after a certain predetermined time, treatment liquid enters the passage 7 through the second end E2 of the tube T and leaves the passage through the first end E1 of the tube T. On the, the alternating circulation means 18 are shown diagrammatically by a reversible circulation pump driven by a drive motor capable of rotating in both directions of rotation.

[0070] In operation, the method implementing the system S according to the invention comprises the following preliminary steps: - mounting the cathode 2 on the weapon tube T by means of the two connecting flanges 21; - mounting the bearing ring assembly 60 around the tube T and the cathode 2; - mounting the connector module 22 around the first insulating module 40A; - fixing the first insulating module 40A on the first end E1 of the tube T and fixing the second insulating module 40B on the second end E2 of the tube T.For this, for each insulating module 40A, 40B, a key corresponding to the hexagonal profile 401 is used to screw the module 40A, 40B onto the threads T1, T2; - fixing the second electrically conductive module 41B to the second insulating module 40B; - introducing the anode 3 inside the tube T by introducing the anode 3 from the first insulating module 40A, until the threads 31 of the second end of the anode 3 cooperate with the tapped bore 413 of the second electrically conductive module 41B; - fixing the first electrically conductive module 41A to the first end of the anode 3 by screwing the reinforcing rod 33 into the tapped bore 413, then fixing the first electrically conductive module 41A to the first insulating module 40A; - applying traction to the anode 3.For this, a first operator holds the first insulating module 40A in position relative to the tube T using a key 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 in rotation. A second operator screws the second insulating module 40B onto the tube T using a corresponding key and applies a tightening torque, in particular 130 dN.m. Due to the reversed screw threads of the tapped bores 404, 413, this screwing allows the anode 3 to be pulled between the two electrically conductive modules 41A, 41B; - the weapon tube T to be placed on the rotation drive means 5 carried by the chassis assembly 1.For this, the bearing ring assembly 60 is placed on the pair of rollers 59 mounted free to rotate and a region of the tube T located between the cathode 2 and the second assembly forming interface 4B is placed on the pairs of rollers 57 driven in rotation by the motor 50; - the fixing of the first and second conical modules 42A, 42B to the first and second electrically conductive modules 41A, 41B, respectively; - if necessary, in particular in the case of a very long tube T, the mounting of the brackets 12 on the supporting frame 10 and the suspension of the electric cables 9 and the hydraulic pipes 17 to these brackets 12.

[0071] Once these preliminary steps have been carried out, the tube T to be treated is capable of forming a cathode and is positioned in the desired non-vertical position, in particular horizontally, and the anode 3 is kept strictly coaxial with the longitudinal axis X0 of the tube T.

[0072] The electrochemical treatment method can then comprise the following treatment steps: - connecting the conical modules 42A, 42B to the hydraulic circuit CH; - 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 connection element 23 to the negative pole (-), and to the anode 3 by connecting the connection element 30 of the second electroconductive module 41B to the positive pole (+); - introducing an electrolyte into the longitudinal passage 7 by actuating the circulation means and controlling the pilot means 16; - once the temperature of the surface of the tube T has been homogenized, switching on the current source 8.The passage of an electric current in the treatment liquid flowing in the longitudinal passage 7 allowing the surface treatment of the inner wall Pi of the tube T; - during the surface treatment, the actuation of the means for alternating circulation 18 of the treatment liquid and the means for driving the tube T in rotation 5. Thus, the tube T is caused to pivot around its longitudinal axis X0, in alternating directions of rotation and the treatment liquid passes through the tube T in one longitudinal direction, then in the other.

[0073] Once the surface treatment is completed, the circulation of the treatment liquid is stopped, the tube T is drained, the interface assemblies 4A, 4B are dismantled and the device D is disconnected from the electrical circuit CE and the hydraulic circuit CH.

[0074] It is therefore understood that the system S according to the present invention allows the implementation of a sequence of surface treatments. For example, the system S can implement cleaning of the interior surface of the tube T in order to condition the subsequent adhesion of a deposit, electrolytic chrome plating allowing the deposition of a layer of chrome, one or more rinses, electropolishing, etc. depending on the desired treatment, the control means 16 of the hydraulic circuit CH control the fluid connection between the tank C1 and C n containing the appropriate treatment liquid and the device D. For example, for cleaning purposes, the device D according to the invention is passed through by an etching liquid (acid, base, etc.), whereas for chrome plating purposes, the device D is passed through by a chrome-based liquid. Thus, the number of storage tanks C1 to C nand the treatment liquids contained in these tanks are adapted to the desired surface treatments. In addition, current is brought into the CE electrical circuit only when the treatment to be carried out is electrochemical.

[0075] It is understood that the particular embodiments which have just been described have been given for informational and non-limiting purposes, and that modifications may be made without departing from the scope of the present invention.

Claims

Device (D) for the electrochemical surface treatment of an inner surface of a longitudinal tubular element (T) made of an electrically conductive material, in particular for the electrolytic metallic coating of an inner wall (Pi) of a weapon barrel (T), the tubular element (T) having a longitudinal axis (X0) and being open at first and second ends (E1, E2), which device (D) comprises: - a frame assembly (1) configured to support such a tubular element (T) so as to allow the tubular element (T) to rotate about its longitudinal axis (X0); - at least one cathode (2) intended to be connected to the negative pole of a current source (8) and configured to be electrically connected to the tubular element (T); - a longitudinal anode (3) intended to be connected to the positive pole of the current source (8) and configured to be placed inside the tubular element (T),coaxially to the longitudinal axis (X0) and at least over the entire length of the tubular element (T);- means forming a sealed interface (4A, 4B) configured to cooperate removably with the tubular element (T) at the first (E1) and second (E2) ends of the tubular element (T) and to ensure the sealing of said first and second ends (E1, E2), and to cooperate with the anode (3) in order to ensure its centering relative to the tubular element (T), the means forming a sealed interface (4A, 4B) comprising at least a first inlet and outlet orifice (424) capable of communicating with the first open end (E1) of the tubular element (T) and at least a second inlet and outlet orifice (424) capable of communicating with the second open end (E2) of the tubular element (T), such that in use,a sealed longitudinal passage (7) is formed between the anode (3) and the inner surface of the tubular element (T) from the first (E1) to the second (E2) end of the tubular element (T), the inlet and outlet ports (424) being intended to be connected to a source of treatment liquid (C1-C, n ); and- means for driving the tubular element (T) in rotation around its longitudinal axis (X0), characterized in that the frame assembly (1) is capable of supporting the tubular element (T) in a non-vertical orientation of the latter and that the device (D) further comprises means for applying traction (6) to the anode (3) configured to, when the anode (3) is mounted inside the tubular element (T), act on at least one of the two ends of the anode (3) in order to prevent bending of the anode (3). Device (D) according to claim 1, characterized in that the traction means (6) of the anode (3) are configured to allow adjustment of the traction by screwing the anode (3) onto one of the means forming a sealed interface (4A, 4B). Device (D) according to any one of claims 1 and 2, characterized in that the means for applying traction (6) to the anode (3) comprise at least one first threaded bore (404) and at least one second threaded bore (413) provided in the means forming a sealed interface (4A, 4B), the or one of the first threaded bores (404) being configured to cooperate with one of the ends (E1, E2) of the tubular element (T), in particular the second end (E2), and the or one of the second threaded bores (413) being configured to cooperate with an external thread (31) provided on the corresponding end region of the anode (3), said first threaded bore (404) having a screw pitch that is reversed relative to the screw pitch of said second threaded bore (413), such that in use, when said first threaded bore (404) is screwed onto the end of the tubular element (T) and the other end of the anode (3) is held fixed,the end region of the anode (3) carrying the external thread (31) is caused to screw into said second tapped bore (413)., Device (D) according to any one of claims 1 to 3, characterized in that the means forming a sealed interface (4A, 4B) comprise a first (4A) and a second (4B) assembly forming an interface, the first assembly forming an interface (4A) comprising a first module made of electrically insulating material (40A) configured to cooperate with the first end (E1) of the tubular element (T) and to be crossed by the anode (3) and a first module made of electrically conductive material (41A) fixed to the first module made of electrically insulating material (40A) and configured to cooperate with the first end of the anode (3),the second assembly forming an interface (4B) comprising a second module made of electrically insulating material (40B) configured to cooperate with the second end (E2) of the tubular element (T) and to be crossed by the anode (3) and a second module made of electrically conductive material (41B) fixed to the second module made of electrically insulating material (40B) and connected to the second end of the anode (3) via the means for applying traction to the anode (6)., Device (D) according to any one of claims 1 to 4, characterized in that the at least one cathode (2) is a peripheral cathode comprising a metal rod (20) intended to be positioned outside the tubular element (T) and along a generatrix thereof, the rod (20) carrying at least one connecting flange (21) to the tubular element (T) and a connector module (22) intended to connect the rod to (20) the current source (8), the connector module (22) being fixed to the means forming a sealed interface (4A, 4B) while being electrically insulated from the anode (3), so that in use, the tubular element (T) takes on the function of cathode. Device (D) according to any one of claims 1 to 5, characterized in that the chassis assembly (1) comprises a supporting chassis (10) and a movable chassis mounted on the supporting chassis (10) and movable relative to the supporting chassis (10), at least pivoting about a pivot axis, the rotational drive means (5) of the tubular element (T) being integral with the movable chassis, the amplitude of the pivoting of the movable chassis about the pivot axis allowing, in use, the tubular element (T) to form an angle of inclination relative to a horizontal plane of between 0 and 90 degrees inclusive. Device (D) according to any one of claims 1 to 6, characterized in that the rotational drive means (5) of the tubular element (T) are configured to produce an alternating rotational movement of the tubular element (T), so that in use, the tubular element (T) is able to be rotated, over a determined angular range, alternately in a given direction of rotation, then in the opposite direction of rotation. System (S) for the electrochemical surface treatment of an inner surface of a tubular element (T) made of electrically conductive material, characterized in that it comprises a device (D) according to any one of claims 1 to 7, which system (S) further comprises:an electrical circuit (CE) comprising a current source (8) whose positive pole is connected to the anode (3) and whose negative pole is connected to the at least one cathode (2); anda hydraulic circuit (CH) connected to the first and second inlet and outlet ports (424) of the device (D) and comprising at least one source of treatment liquid (C1-C n) and means for circulating treatment liquid, which hydraulic circuit (CH) further comprises alternating circulation means (18) capable of circulating the treatment liquid in the longitudinal passage (7), initially from the first (E1) to the second (E2) end, then in a second step inversely from the second (E2) to the first (E1) end. System (S) according to claim 8, characterized in that the anode (3) is connected to the current source (8) via a first conductive connection element (30) connected on the one hand to the positive pole of the current source (8) and on the other hand to the second module made of electrically conductive material (41A; 41B), and in that the cathode (2) is connected to the current source (8) via a second conductive connection element (23) connected on the one hand to the negative pole of the current source (8) and on the other hand to the connector module (22). System (S) according to any one of claims 8 and 9, characterized in that the hydraulic circuit (CH) comprises a plurality of treatment liquid storage tanks (C1-C n ), each tank (C1-C n ) being associated with at least one conduit (14) for the delivery of the liquid which it contains, which conduit (14) is equipped with a solenoid valve (15), control means (16) being provided to control the solenoid valves (15) and to allow fluid connection to one of the storage tanks (C1-C n ) to the device (D).

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