WO2024116049A1

WO2024116049A1 - 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

Info

Publication number: WO2024116049A1
Application number: PCT/IB2023/061908
Authority: WO
Inventors: Marc Puygrenier; Thierry PORTE
Original assignee: Knds France Mechanics
Priority date: 2022-11-29
Filing date: 2023-11-27
Publication date: 2024-06-06
Also published as: FR3142493A1

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 electroconductive material, in particular a weapon tube, and system comprising such a device

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

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 electroconductive material, in particular of a weapon tube. 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 else electrolytic polishing (electropolishing), but without limit yourself to it.

In the field of armaments, which is one of the applications of the present invention, it is known to coat the interior wall of a weapon tube with a thin layer of chromium in order to improve the resistance of the tube of weapon to wear and friction during the passage of projectiles and, therefore, to increase the number of projectiles that the weapon tube can fire during its service life. Indeed, chromium has significant hardness and low chemical interaction with other metals, these two combined properties considerably limit the wear of parts. Chrome plating also has the benefit of adding a corrosion-resistant coating to the weapon tube, which increases the life of the weapon tube, especially in humid environments.

This layer of chromium is generally applied electrolytically. For this purpose, an anode is introduced coaxially into the weapon tube and over the entire length of the weapon tube. A suitable electrolyte, such as a chromic acid bath, is then allowed to flow in one direction through the weapon tube, between the anode and the inner wall of the weapon tube, while a voltage is applied to the anode and the weapon tube. The electric current flowing from the anode to the weapon tube via the electrolyte causes a thin layer of chromium to be deposited on the inner surface of the weapon tube.

Patent GB712314, published on 07/21/1954, discloses such a process for electroplating the interior surface of a weapon tube, as well as an apparatus for implementing this process. In order to obtain a regular deposit, the weapon tube is positioned vertically and is made to rotate around its longitudinal axis.

This solution is suitable for light or medium caliber weapons tubes. However, due to the vertical positioning of the weapon tube, this solution presents disadvantages in its application to large caliber weapon tubes several meters long since it requires having a very significant height and means suitable handling methods.

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 electroconductive material, in particular of a large caliber weapon tube, in a space having a reduced volume in height, while ensuring the distribution of a metallic deposit as constant as possible in thickness in the case of a metallic coating.

The solution according to the present invention is based on the use of a device making it possible to orient the tubular element in a non-vertical orientation, such as for example horizontally, and further comprising both means allowing the implementation traction of the anode and the means for rotating the tubular element around its longitudinal axis. The means for putting the anode in traction 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 interior wall of the tubular element, in thus avoiding its sagging. The means for driving the tubular element in axial rotation make it possible to prevent gases resulting in particular from electrolysis from accumulating at a given point of the tubular element, a point which would then receive a lesser deposit of metal in the case of a metallic covering. Together, the means for putting the anode in traction and the means for driving the axial rotation of the tubular element make it possible to prevent a phenomenon of shrinkage of the internal diameter of the tubular element, of the " hourglass effect”, in which the metal deposit has a profile comparable to that of an hourglass.

The solution according to the present invention is also based on the use of a system comprising such a device and further comprising means of alternating circulation capable of circulating a treatment solution through the tubular element in both directions, alternately. In the case of a metallic coating, the means of alternating circulation make it possible to ultimately obtain a metallic coating which is deposited with the same speed of metal deposition 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 interior surface of the tubular element a blunderbuss shape.

The present invention therefore relates to a device for the electrochemical surface treatment of an interior surface of a longitudinal tubular element made of electroconductive material, in particular for the electrolytic metallic coating of an interior wall of a weapon tube , the tubular element having a longitudinal axis and being open at first and second ends, which device comprises:
- a chassis 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 level of 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 one 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 passage sealed longitudinal is formed between the anode and the interior 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 processing liquid ; And
- means for driving the tubular element in rotation around its longitudinal axis,
characterized by the fact that the chassis assembly is capable of supporting the tubular element in a non-vertical orientation of the latter and that the device further comprises means for putting the anode in traction configured for, 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.

Thanks to the presence of both means for putting the anode in traction and means for driving the axial rotation of the tubular element, we see that the appearance of an "hourglass" effect can be avoided during a metal deposition operation using the device according to the invention. Furthermore, it turns out that the presence of means for putting the anode in tension 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.

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

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 improves the corrosion resistance of the anode and allows it to have sufficient mechanical strength over time.

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

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 capable of being placed in rotation, over a determined angular range, alternately in a given direction of rotation, then in the opposite direction of rotation.

Advantageously, the rotation drive means are configured to authorize an axial rotation movement in one or other of the two directions of rotation over a maximum angular range of 360 degrees, corresponding to one revolution of the tubular element around of its longitudinal axis.

In a particular embodiment, the rotation 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 whose rollers are mounted to rotate around axes intended to be parallel to the longitudinal axis of the tubular element. At least some of the rollers are rotated by the pulley-belt assembly, so as to themselves rotate the tubular element.

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

Preferably, in use, the tightening torque applied to put the anode in traction is of the order of 130 dN.m.

In a particular embodiment, the means for putting the anode in traction 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 an inverse thread pitch relative to the thread 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 made to screw into said second threaded bore.

Advantageously, a reinforcing rod is provided for the removable fixing of the anode to the means forming a sealed interface at the level of the end region of the anode opposite the end region carrying the external thread, the rod having a first and a second external threads which cooperate, respectively, with a third threaded bore of the means forming a sealed interface and a threaded axial orifice of the anode. Such a rod makes it possible to increase the resistance at the level of the fixing zone.

Preferably, the tapped axial hole is made in the first end region of the anode, and the external thread is provided on the second end region of the anode.

Advantageously, the means forming a sealed interface comprise, to the right of the or each first tapped bore, a hexagonal external profile of electrical insulating material. Such a hexagonal profile is adapted to cooperate with a conventional tool, in particular a key capable of ensuring rotational locking or tightening, having a corresponding hexagonal profile.

In a particular embodiment, the means forming a sealed interface comprise a first and a second interface forming assembly, the first interface forming assembly comprising a first module of electrical insulating material configured to cooperate with the first end of the tubular element and to be crossed by the anode and a first module of electrically conductive material fixed to the first module of electrical insulating material and configured to cooperate with the first end of the anode, the second interface assembly comprising a second module of electrical insulating material configured to cooperate with the second end of the tubular element and be crossed by the anode and a second module of electroconductive material fixed to the second module of electrical insulating material and connected to the second end of the anode via the means for putting the tension in tension the anode.

Preferably, each module of electrical insulating material is made of PVDF (polyvinylidene fluoride) and each module of electroconductive material is made of steel.

Preferably, a conical sealed connection module made of an electrical insulating material and intended to be connected to a source of treatment liquid is fixed to each module of electroconductive material, each conical module comprising a converging orifice in communication with the orifice(s) input/output means forming a waterproof interface. Such a conical module makes it possible to avoid turbulence and maintain laminar flow.

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 generator thereof, the rod carrying at least one flange of 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 isolated from the anode, so that in use, the tubular element takes the function of cathode.

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

In a particular embodiment, the chassis assembly comprises a carrier frame and a movable frame mounted on the carrier frame and movable relative to the carrier frame, at least pivotable around a pivot axis, the rotation drive means of the tubular element being integral with the movable frame, the amplitude of the pivoting of the movable frame around the pivot axis authorizing, in use, the tubular element to form an angle of inclination with respect to a horizontal plane between 0 and 90 degrees included.

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

Preferably, the supporting chassis is a rolling chassis, for example equipped with at least a first wheel assembly and a second wheel assembly.

The present invention also relates to a system for the electrochemical surface treatment of an interior surface of a tubular element made of electroconductive material, characterized in that it comprises a device as defined above, which system comprises in besides :
- 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 orifices of the device and comprising at least one source of treatment liquid and means for circulating treatment liquid, which hydraulic circuit further comprises means for circulating it alternating capable of circulating the treatment liquid in the longitudinal passage, initially from the first towards the second end, then in a second stage inversely from the second towards the first end.

Thanks to the presence of both means for putting the anode in traction, means for driving the axial rotation of the tubular element, and means for alternating circulation of a treatment liquid, we can notice that the appearance of a “blunderbuss” phenomenon can be avoided during a metal deposition operation implementing the system according to the invention.

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

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 electroconductive 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.

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.

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 intended to control the solenoid valves and allow one of the storage tanks to be fluidly connected to the device.

Advantageously, the plurality of storage tanks comprises at least one storage tank for acid attack solution and at least one storage tank for basic attack solution or liquid with a view to carrying out a rinsing operation, at least a storage tank for chromium-based solution for carrying out a chrome plating operation, a storage tank for electropolishing solution and a storage tank for neutralization solution or liquid in order to eliminate hexavalent chromium.

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

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

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

is an enlarged perspective view of the rotation drive means, part of the chassis assembly as well as a section of the tube being omitted for greater clarity;

is an enlarged perspective view of the device at a first end of the tubular element;

is a longitudinal sectional view of the enlarged region of the ;

is an enlarged perspective view of the device at a second end of the tubular element;

is a longitudinal sectional view of the enlarged region of the ; And

represents a diagram of the system according to the present invention.

If we first refer to Figures 1 to 7, we can see that the device D for the electrochemical surface treatment according to the present invention can be applied to the surface treatment of the interior wall Pi of a tube d weapon T, in particular a rifled weapon tube. In the remainder of the description, the term "weapon tube" or "tube" 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 weapon tubes T, the element being able to be any longitudinal tubular element made of electrically conductive material, including a tubular element of great length.

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, drive means in rotation 5 of the weapon tube T, and the traction means 6 of the anode 3.

The function of the chassis assembly 1 is to support the weapon tube T to be treated in a non-vertical orientation of the weapon tube T.

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 carrier frame 10 carries the rotation drive means 5 of the tube T. The carrier frame 10 is a mechanically welded frame, on braked casters 11, comprising longitudinal longitudinal members connected by crosspieces. As can be seen on the , brackets 12 can be provided at each longitudinal end of the supporting frame 10, in order to allow the suspension of electrical cables 9 and liquid pipes 17 intended to be connected to the device D. Likewise, a pair of glasses 13 forming frames arranged in vertical planes and capable of being crossed by the weapon tube T, can be mounted on the upper longitudinal members of the supporting frame 10. The upper longitudinal 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.

Alternatively, the chassis assembly 1 could also include a mobile chassis (not shown) mounted on the supporting chassis 10 and carrying the rotational drive means 5 of the tube T. For example, the mobile chassis could be mounted movable to pivot relative to the carrier frame 10 around a horizontal pivot axis orthogonal to the longitudinal axis of the carrier frame 10. The pivoting movement of the movable frame around the pivot axis could be controlled by a jack connected to the carrier frame 10 and articulated to the movable frame around an axis of rotation parallel to the pivot axis. Thus, in use, an extension of the cylinder rod causes a movement of the mobile chassis and therefore of the weapon tube T which it supports towards a high position, for example a position in which the longitudinal axis X0 of the weapon tube weapon is horizontal. Conversely, retraction of the cylinder rod causes a movement of the mobile frame and therefore of the weapon tube T towards a low position in which the longitudinal axis X0 of the weapon tube T forms an angle between 0 and 90 degrees from a horizontal plane. It should be emphasized that the actuator could be replaced by any other suitable linear actuator. Thus, such a chassis 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 the axial position relative to the mobile chassis, in particular in the case where the angle of inclination is large, an anti-slip ring is mounted around the tube and abuts against an element forming stop of the mobile chassis.

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 connection flanges 21 electroconductive 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 electroconductive material is adapted around a module of electrical insulating material 40A means forming a sealed interface 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 powered on, the current circulates in an electrical circuit CE up to the connection element 23, then circulates successively in the connector module 22, in the rod 20, in the flanges 21 and in the wall of the tube T.

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 mounted state, the anode 3 is centered coaxially with the weapon tube T and projects from either side of the ends E1, E2 of the weapon tube T. An annular channel is formed between the anode 3 and the inner wall surface Pi of the tube T, which channel defines a longitudinal passage 7 from one open end to the other of the tube T. Thus, the diameter of the anode 3 depends on the surface treatment to be applied, for example, the desired metal deposit thickness, and the dimensions of the tube T.

As can be seen on the , the anode 3 is connected to the positive pole (+) of a current source 8 via a module made of electroconductive material 41B of the means forming a sealed interface 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 a tapped bore 413 of module 41B. Thus, once the current source 8 is energized, the current flows in an electrical circuit CE up to the connection element 30, then circulates in the electroconductive module 41B and in the anode 3. As can be seen on 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, via its threaded end, to another electroconductive module 41A of the means forming a sealed interface 4A . This reinforcing rod 33 comprises threaded longitudinal end regions whose external threads engage, respectively, with a threaded bore 413 of the electroconductive module 41A and with the threaded axial orifice 32 of the anode 3.

The means forming a sealed interface 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 C ₁ to C _n and the longitudinal passage 7 formed inside the tube T. The means forming a sealed interface 4A, 4B comprise first 4A and second 4B together forming an interface cooperating, respectively, with the first E1 and second E2 ends of the weapon tube T and the anode 3.

If we refer to Figures 6 and 7, we can see that the first assembly forming an interface 4A comprises a first module made of electrical insulating material 40A, a first module of electrically conductive material 41A and a first conical module 42A for waterproof connection.

The first module made of electrical insulating material 40A is a tubular body made for example of PVDF and having a section with a hexagonal external profile 401, a cylindrical section 402 and an annular section 403. The interior wall of the section with a hexagonal external profile 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 in such a way 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 the cylindrical section 402, so as to allow the assembly of this module 40A with the first electroconductive module 41A by removable fixing members, in particular bolts 43.

The first module made of electroconductive 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. 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 tapped 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 electroconductive 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 via 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 converging orifice 423 of the first conical module 42A.

The first conical module 42A is a tubular body made of an electrical insulating material, in particular plastic, and having an annular section 420 for attachment to the first electroconductive 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 coming from 'a source of treatment liquid C ₁ 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 anode 3 and tube T.

If we refer to Figures 4 and 5, we can see that the second assembly forming an interface 4B comprises a second module made of electrical insulating material 40B, a second module made of electrically conductive material 41B and a second conical module 42B for waterproof connection.

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 a 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.

The second module made of electroconductive material 41B is similar to the first electroconductive module 41A, with the exception of the fact that it comprises a radial orifice 415 at the level of 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 with the thread of the tapped bore 413 designated by the second tapped bore. The screw pitch of this second tapped bore 413 is reversed relative to the screw 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 maintained fixed in rotation by blocking rotation 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 in the second electroconductive module 41B, therefore opposite the first end of the anode 3. The threaded bores 404, 413 of the means forming a sealed interface 4A, 4B therefore constitute the means for putting the anode 3 in traction.

The second conical module 42B is similar to the first conical module 42A.

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 over 360 degrees in a first direction of rotation then an axial rotation over 360 degrees in a second opposite direction of rotation, alternately .

As can be seen on the , these drive 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 include 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 causes 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 longitudinal 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 are provided a pair of rollers 59 mounted free to rotate around axes of rotation parallel to each other and parallel to the longitudinal axis X0. These rollers 59 support the weapon tube T via a rolling ring assembly 60, which if necessary compensates for the possible conicity of the weapon tube T. The rolling ring assembly 60 is mounted around the weapon tube T and is crossed 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 rotates around its longitudinal axis X0.

If we now refer to the , 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.

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 electroconductive 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.

The hydraulic circuit CH comprises a plurality of treatment liquid storage tanks C ₁ to C _n constituting at least one source of treatment liquid. Each tank C ₁ 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 including in particular a man-machine interface, a controller with probes and sensors. Means for circulating treatment liquid, such as pumps, allow the circulation of the liquid through the upstream conduits 14. Downstream conduits 17 connected to the upstream conduits 14 are in fluid communication with the inlet/outlet orifices 424 first 42A and second 42B conical modules in order to allow the circulation of a treatment liquid between one of the tanks C ₁ to C _n and the longitudinal passage 7. The circulation of the liquid in the downstream conduits 17 is controlled by means of alternating circulation 18 capable of circulating one of the treatment liquids through the longitudinal passage 7 alternately in a first direction of circulation and in a second direction of circulation (two-way arrows on the ). Thus, treatment liquid enters passage 7 through the first end E1 of tube T and leaves passage 7 through the second end E2 of tube T, then after a certain predetermined time, treatment liquid enters passage 7 through the second end E2 of the tube T and exits the passage through the first end E1 of the tube T. On the , the alternating circulation means 18 are schematized by a reversible circulation pump driven by a drive motor capable of rotating in both directions of rotation.

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 via the two connection 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 electroconductive module 41B to the second insulating module 40B;
- the introduction of the anode 3 inside the tube T by introduction of 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 electroconductive module 41B;
- fixing the first electroconductive 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 electroconductive module 41A to the first insulating module 40A;
- putting the anode 3 in traction. To do 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 module insulator 40A and therefore the first electroconductive module 41A and the anode 3 are blocked in rotation. A second operator screws the second insulating module 40B onto the tube T using a corresponding wrench and applies a tightening torque, in particular 130 dN.m. Due to the reversed threads of the tapped bores 404, 413, this screwing allows the anode 3 to be put into traction between the two electroconductive modules 41A, 41B;
- the installation of the weapon tube T on the rotation drive means 5 carried by the chassis assembly 1. For this, the rolling 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 interface forming assembly 4B is placed on the pairs of rollers 57 rotated by the motor 50;
- fixing the first and second conical modules 42A, 42B to the first and second electroconductive modules 41A, 41B, respectively;
- if necessary, particularly in the case of a very long T tube, the mounting of the jibs 12 on the supporting frame 10 and the suspension of the electrical cables 9 and the hydraulic pipes 17 to these jibs 12.

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.

The electrochemical treatment process can then include the following treatment steps:
- the connection of the conical modules 42A, 42B to the hydraulic circuit CH;
- the connection of 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 the connection of 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 (+);
- the introduction of an electrolyte into the longitudinal passage 7 by actuation of the circulation means and control of the control 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 interior wall Pi of the tube T;
- during the surface treatment, the actuation of the means 18 for alternating circulation of the treatment liquid and the rotation drive means 5 of the tube T. Thus, the tube T is made to pivot around its longitudinal axis X0 , in alternating directions of rotation and treatment liquid passes through the tube T in one longitudinal direction, then in the other.

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

We therefore understand 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 chromium plating allowing the deposition of a layer of chromium, one or more rinsings, a electropolishing, etc. depending on the desired treatment, the control means 16 of the hydraulic circuit CH control the fluid connection between the tank C ₁ to C _n containing the appropriate treatment liquid and the device D. For example, for cleaning, the device D according to the invention is passed through by an etching liquid (acid, base, etc.), whereas for chrome plating, device D is passed through by a chromium-based liquid. Thus, the number of storage tanks C ₁ to C _n and the treatment liquids contained in these tanks are adapted to the desired surface treatments. In addition, current is caused to flow in the electrical circuit CE only when the treatment to be carried out is electrochemical.

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

Claims

Device (D) for the electrochemical surface treatment of an interior surface of a longitudinal tubular element (T) made of electroconductive material, in particular for the electrolytic metallic coating of an interior wall (Pi) of a tube of weapon (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 chassis assembly (1) configured to support such a tubular element (T) so as to allow the tubular element (T) to rotate around 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 with 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 one first inlet and outlet port (424) capable of communicating with the first open end (E1) of the tubular element (T) and at least one second inlet and outlet port (424) capable to communicate with the second open end (E2) of the tubular element (T), so that in use, a sealed longitudinal passage (7) is formed between the anode (3) and the interior 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 (C 1 -C n ); And
- means for driving the tubular element (T) in rotation (5) around its longitudinal axis (X0),
characterized by the fact that the chassis 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 traction means (6) of 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 to prevent sagging 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 the one of the means forming a waterproof interface (4A, 4B).
Device (D) according to any one of claims 1 and 2, characterized in that the traction means (6) of 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 element tubular (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 reversed relative to the thread 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 threaded 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 interface (4A) comprising a first module of electrical 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 of electroconductive material (41A) fixed to the first module of electrical insulating material (40A) and configured to cooperate with the first end of the anode (3), the second interface assembly (4B) comprising a second module of electrical 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 of electrically conductive material (41B) fixed to the second module of electrical insulating material (40B) and connected at the second end of the anode (3) via the anode traction means (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 connection 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 isolated from the anode (3), such 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 carrier frame (10) and a movable frame mounted on the carrier frame (10) and movable relative to the supporting frame (10), at least pivotable around a pivot axis, the rotation drive means (5) of the tubular element (T) being integral with the movable frame, the amplitude of the pivoting of the movable frame around the pivot axis authorizing, 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 rotation drive means (5) of the tubular element (T) are configured to produce an alternating rotation 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 interior surface of a tubular element (T) made of electroconductive 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); And

a hydraulic circuit (CH) connected to the first and second inlet and outlet orifices (424) of the device (D) and comprising at least one source of treatment liquid (C 1 -C n ) and liquid circulation means treatment, 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) towards the second (E2) end, then in a second step inversely from the second (E2) towards 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 electroconductive material (41A; 41B), and by the fact that the cathode (2) is connected to the current source (8) by the 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 (C 1 -C n ), each tank (C 1 -C n ) being associated with at least one conduit (14) for delivering the liquid it contains, which conduit (14) is equipped with a solenoid valve (15), control means (16) being provided to control the solenoid valves (15) and allow one of the storage tanks (C 1 -C n ) to be fluidly connected to the device (D).