EP1893789B1 - Device and method for maintaining and connecting an anode rod on an anode frame of an aluminum electrolytic cell - Google Patents

Description

TECHNICAL AREA

The present invention relates to a connector, a hook and a device for holding and connecting an anode rod against an anode frame of an aluminum electrolysis cell, and a method of maintaining and connection of such anode rod.

Aluminum metal is produced industrially by electrolysis of alumina in solution in an electrolyte bath, according to the Hall-Heroult method. The electrolyte bath is contained in an electrolysis cell comprising a steel box lined internally with refractory and / or insulating materials, and at the bottom of which is located a cathode assembly. Anodes, typically of carbonaceous material, are partially immersed in the electrolyte bath.

Each anode is provided with a metal rod for its electrical and mechanical connection to an anode frame movable relative to a gantry fixed above the electrolytic cell. Each anode rod is connected to the anode frame using hooks disposed on either side of the anode rod and a removable connector adapted to be deposited on these hooks and to press the anode rod against the anode frame.

• lors du démarrage de l'installation, au tout début du régime de fonctionnement continu, après la phase de préchauffage ;
• en régime de fonctionnement continu, lorsque le cadre anodique a atteint la limite basse de sa course et qu'il est nécessaire de le remonter par rapport à l'ensemble des anodes afin de poursuivre l'exploitation ;
• lorsque les anodes sont trop usées et/ou détériorées et qu'il est nécessaire de les changer.

During the life of the installation, the connection of the anode rods to the anode frame is carried out in different cases:

• when starting the installation, at the very beginning of the continuous operating mode, after the preheating phase;
• in continuous operating mode, when the anode frame has reached the lower limit of its travel and it is necessary to raise it with respect to all the anodes in order to continue the operation;
• when the anodes are too worn and / or deteriorated and need to be changed.

However, during this connection operation, it happens that the anode rods are poorly positioned, for example arranged not perfectly vertical but slightly oblique. This problem is particularly encountered when changing the anodes, because, then, they can be maintained in this incorrect position due to the crust that is formed on the surface of the electrolyte bath. Due to the apparent behavior imparted by the crust, this poor positioning is difficult to detect, and the connector seems to play its role perfectly.

However, under continuous operating conditions, the crust melts and can no longer maintain the anode rod. The latter is then no longer maintained satisfactorily against the anode frame by the connector because of the initial bad positioning. It follows a degradation of the electrical and mechanical connection, which affects the performance of the installation. In the worst case, the anode rod can slide relative to the anode frame and fall to the bottom of the electrolysis cell, thus requiring long and expensive interventions.

In general, this problem arises when, for various reasons, the position of the anode changes. Indeed, the forces exerted on the anode rod are then modified with respect to the initial position in which the clamping of the anode rod was satisfactory. As a result, the anode rod is no longer properly held against the anode frame by the connector.

The documents EP 0 178 766 and US 5,876,585 propose temporary connection devices that secure the anode rod against the anode frame when starting the installation. These connecting devices comprise means, such as rollers and control systems. Belleville type springs or washers, allowing relative movement of the anode rod while maintaining a satisfactory tightening the different stages of expansion and deformation of the elements of the electrolysis cell during pre-heating.

However, these devices are only intended to be used during the preheating phase of the installation, during which the anodes are placed on the bottom of the tank. In continuous operating mode, when the anodes are no longer on the bottom of the tank, the rollers would not allow to ensure sufficient clamping of the anode rods. Thus, in continuous operation, the document US 5,876,585 plans to use connecting devices without compensation means such as rollers and springs.

In addition, these devices are insufficient to compensate for an initial bad positioning of the anode rod with respect to the anode frame, because, in this case, the consequences on the displacement of the rod are much greater than those resulting from the rise in temperature of the cell components.

The French request FR 2 039 543 discloses a connector comprising a body having two levers for exerting pressure on the anode rod towards the anode frame by at least one bearing face, two substantially coaxial lateral rods each protruding laterally from said body and intended to rest each on a hook attached to the anode frame, on either side of the rod and a clamping screw adapted to cause the pivoting of the levers around the axis of the lateral rods, so that the connector can be in two particular geometrical configurations: a tightening configuration (or a "tight configuration") in which the bearing surface of the levers is in contact with the anode rod and urges it towards the anode frame substantially perpendicular to it and a configuration of loosening (or a "loosened configuration"), in which the bearing surface of the levers does not exert pressure on the anode rod. Such a connector, which is currently widely used in electrolysis plants for both pre-heating and continuous operation, also does not have a means of compensation allowing a significant relative displacement of the anode rod while maintaining a satisfactory clamping. of it on the anode frame.

The present invention aims to remedy the disadvantages mentioned above, by providing a solution to ensure excellent clamping of the anode rod against the anode frame, despite possible initial incorrect positioning, by means of a connector, a hook and / or a device that can be used in preheating phase but also in continuous operation mode.

• un corps comportant au moins une partie mobile comprenant une face d'appui, ladite partie mobile se déplaçant de telle sorte que la dite face d'appui exerce une pression sur la tige d'anode, en suivant une direction sensiblement perpendiculaire à la surface de contact du cadre anodique;
• un couple de protubérances latérales sensiblement axiales dépassant chacune latéralement dudit corps, orientées substantiellement perpendiculairement à ladite direction et étant destinées à reposer chacune sur un crochet fixé au cadre anodique, de part et d'autre de la tige d'anode;
• et un actionneur apte à provoquer le déplacement de ladite partie mobile pour l'amener entre une position de serrage, dans laquelle ladite face d'appui est en contact avec la tige d'anode et la sollicite vers le cadre anodique lorsque lesdites protubérances latérales reposent sur lesdits crochets, et une position de desserrage, dans laquelle ladite face d'appui n'exerce pas de pression sur la tige d'anode;

caractérisé en ce que ledit connecteur présente au moins partiellement une géométrie et/ou est constitué au moins partiellement d'un matériau tels que, lorsque ledit actionneur amène la partie mobile en position de serrage, ledit connecteur subit une déformation élastique suffisante pour que, en cas de changement de position de la tige d'anode par rapport au cadre anodique, ledit connecteur, par retour élastique au moins partiel vers sa position de repos, reste en contact avec ladite tige d'anode et continue ainsi à assurer un maintien ferme de ladite tige d'anode contre ledit cadre anodique.For this purpose, and according to a first aspect, the invention relates to a connector for holding and connecting an anode rod against an anode frame of an aluminum electrolysis cell, comprising:

• a body comprising at least one movable part comprising a bearing face, said moving part moving so that said bearing face exerts pressure on the anode rod, in a direction substantially perpendicular to the surface of the contact of the anode frame;
• a pair of substantially axial lateral protuberances each protruding laterally from said body, oriented substantially perpendicular to said direction and being intended to rest each on a hook fixed to the anode frame, on either side of the anode rod;
• and an actuator adapted to cause the displacement of said movable part to bring it between a clamping position, in which said bearing face is in contact with the anode rod and urges it towards the anode frame when said lateral protuberances rest on said hooks, and a loosening position, wherein said bearing face does not exert pressure on the anode rod;

characterized in that said connector has at least partially a geometry and / or consists at least partially of a material such that, when said actuator brings the moving part into the clamping position, said connector undergoes a sufficient elastic deformation so that, in case of change of position of the anode rod relative to the anode frame, said connector, by at least partial springback to its rest position, remains in contact with said anode rod and thus continues to ensure a firm hold of said anode rod against said anode frame.

In other words, the connector according to the invention comprises at least one portion capable of storing an elastic deformation energy sufficient to cause a large displacement of the bearing face towards the anode frame, when the clamping force is released. This particularly elastically deformable part may be all or part of the movable part, a connecting element between the movable part and the actuator, or all or part of the pair of lateral protuberances. Of course, it is also possible to combine several of these parts of the connector so that the connector as a whole has this ability to store said elastic deformation sufficient.

The aim is to store a reserve of mechanical energy in the connector such that in the event of release of the contact stresses related to a relative displacement of the anode rod with respect to the anode frame, the support face of the connector against the anode rod can, by elastic return of said connector, move a certain distance in the direction of said anode rod. In practice, the Applicant has evaluated that said sufficient elastic deformation must result, during an elastic return resulting from a decrease in the clamping force, by a displacement of the bearing face of the moving part in the direction of of the anode frame of at least 0.6 mm, preferably greater than 1mm, or even 2 mm, or even 3mm. Another way of estimating said sufficient elastic deformation is to aim at compensating for an angular displacement of the anode rod with respect to the vertical of at least 0.15 °, and preferably at least 0.3 °.

The portion of the connector capable of storing a large elastic deformation must therefore have such a geometry and consist of a material having a sufficiently high elastic limit for such a displacement, typically greater than 0.6 mm, to result in a deformation purely elastic. Preferably one will choose a material whose elastic limit is greater than 1000 N / mm 2, typically a metal, especially a steel.

• un corps comportant, en tant que parties mobiles, deux leviers destinés à exercer une pression sur la tige d'anode vers le cadre anodique par au moins une face d'appui ;
• en tant que protubérances latérales, deux tiges latérales sensiblement coaxiales dépassant chacune latéralement dudit corps et destinées à reposer chacune sur un crochet fixé au cadre anodique, de part et d'autre de la tige d'anode ;
• et, en tant qu'actionneur, une vis de serrage apte à provoquer le pivotement des leviers autour de l'axe des tiges latérales entre une position de serrage dans laquelle la face d'appui des leviers est en contact avec la tige d'anode et la sollicite vers le cadre anodique sensiblement perpendiculairement à celui-ci et une position de desserrage dans laquelle la face d'appui des leviers n'exerce pas de pression sur la tige d'anode.

A preferred mode of a connector according to the invention comprises:

• a body having, as moving parts, two levers for exerting pressure on the anode rod towards the anode frame by at least one bearing face;
• as lateral protuberances, two substantially coaxial lateral rods each protruding laterally from said body and intended to rest each on a hook attached to the anode frame, on either side of the anode rod;
• and, as actuator, a clamping screw adapted to cause the pivoting of the levers about the axis of the lateral rods between a clamping position in which the bearing surface of the levers is in contact with the anode rod and urges it towards the anode frame substantially perpendicular thereto and a loosening position in which the bearing surface of the levers does not exert pressure on the anode rod.

The two lateral rods may be formed by a single rod passing through the body of the connector. The geometry and the constituent material of at least one lever and / or a lateral rod of the connector are able to allow, during the tightening the screw for holding and connecting the anode rod, sufficient elastic deformation of the connector so that, in case of change of position of the anode rod relative to the anode frame, said connector, by springback at least partially towards its rest position, remains in contact with said anode rod and thus continues to ensure a firm hold of said anode rod against said anode frame. Thus a reserve of mechanical energy is formed in the connector to restore it automatically in case of movement of the anode rod, so that the connection and maintenance of the anode rod against the anode frame is always satisfactory.

For example, the connector has a long enough lateral rod, so that the distance between the body of the connector and the support zone of this rod, intended to rest on the hook attached to the anode frame, is large enough to allow deformation said rod and, consequently, a displacement of the connector body, and consequently of its bearing face on the anode rod, substantially perpendicular to the anode frame, of an amplitude greater than 0.6 mm. Preferably, at least one lateral rod is made of a material whose elastic limit is greater than 1000 N / mm 2, typically a metal, in particular a steel.

Said distance between the body of the connector and the bearing zone of this lateral rod may be greater than 50 mm, or even 90 mm, and the amplitude of displacement of the connector body may exceed 1 mm, or even 2 mm, or even 3 mm. The distance between the connector body and the zone of support of the corresponding lateral rod may be between 20 and 40% of the distance between the bearing zones of the two lateral rods (ie the distance between the two hooks attached to the anode frame).

At least one lever may comprise at least one flange having an indentation made from its upper or lower edge and defining two branches spaced apart from each other in a direction perpendicular to the lateral rods. The bottom of the notch can then form a housing for receiving a lateral rod.

At least one lever may comprise an elastic pad, at least a portion of which forms the bearing surface of said lever on the anode rod. This pad may be in the form of a folded elastic tab on itself, preferably made of metal, especially steel.

According to another aspect, the invention relates to a hook intended to be fixed to the anode frame of an aluminum electrolysis cell for holding and connecting, against the anode frame, an anode rod placed at side of the hook, and on which is intended to rest a connector operable between a clamping position in which the connector is in contact with the anode rod and urges it towards the anode frame substantially perpendicular thereto and a position in which the connector does not exert pressure on the anode rod. The geometry and the constituent material of the hook are able to allow, when the connector is actuated to the clamping position, a sufficient elastic deformation of the hook relative to the anode frame so that the hook can, by at least partial elastic return to its rest position, compensate for any change in the position of the anode rod relative to the anode frame and thus continue to ensure a firm hold of the anode rod against the anode frame. In other words, a reserve of mechanical energy is constituted in the or each hook to be restored automatically in case of movement of the anode rod.

• deux crochets fixés au cadre anodique et entre lesquels la tige d'anode est destinée à être placée ;
• un connecteur comprenant:
  1. a) un corps comportant au moins une partie mobile comprenant une face d'appui, ladite partie mobile se déplaçant de telle sorte que la dite face d'appui exerce une pression sur la tige d'anode, en suivant une direction sensiblement perpendiculaire à la surface de contact du cadre anodique,
  2. b) un couple de protubérances dépassant chacune latéralement dudit corps, orientées globalement perpendiculairement à ladite direction, étant destinées à reposer chacune sur un crochet et
  3. c) un actionneur apte à provoquer le déplacement de ladite partie mobile pour l'amener entre une position de serrage, dans laquelle ladite face d'appui est en contact avec la tige d'anode et la sollicite vers le cadre anodique lorsque lesdites protubérances reposent sur lesdits crochets, et une position de desserrage, dans laquelle ladite face d'appui n'exerce pas de pression sur la tige d'anode. Les crochets et/ou le connecteur présentent au moins partiellement une géométrie et/ou sont au moins partiellement constitués d'un matériau tels que lorsque lesdites protubérances reposent sur lesdits crochets et que ledit actionneur amène la partie mobile en position de serrage, ledit dispositif de maintien et de raccordement subit une déformation élastique suffisante pour que, en cas de changement de position de la tige d'anode par rapport au cadre anodique, ledit connecteur, par retour élastique au moins partiel dudit dispositif vers sa position de repos, reste en contact avec ladite tige d'anode et continue ainsi à assurer un maintien ferme de ladite tige d'anode contre ledit cadre anodique.

According to another aspect, the invention relates to a device for holding and connecting an anode rod against an anode frame of an aluminum electrolysis cell, comprising:

• two hooks attached to the anode frame and between which the anode rod is to be placed;
• a connector comprising:
  1. a) a body comprising at least one movable part comprising a bearing face, said moving part moving so that said bearing face exerts pressure on the anode rod, in a direction substantially perpendicular to the contact surface of the anode frame,
  2. b) a pair of protuberances protruding each laterally from said body, oriented generally perpendicular to said direction, being intended to rest each on a hook and
  3. c) an actuator adapted to cause the displacement of said movable part to bring it between a clamping position, in which said bearing face is in contact with the anode rod and urges it towards the anode frame when said protuberances rest on said hooks, and a release position, wherein said bearing face does not exert pressure on the anode rod. The hooks and / or the connector have at least partially a geometry and / or are at least partially made of a material such that when said protuberances rest on said hooks and said actuator brings the moving part into the clamping position, said device maintenance and connection undergoes sufficient elastic deformation so that, in case of change of position of the anode rod relative to the anode frame, said connector, by at least partial elastic return of said device to its rest position, remains in contact with said anode rod and thus continues to provide a firm hold of said anode rod against said anode frame.

In particular, the device comprises a connector comprising a body comprising two levers having at least one bearing face, two substantially coaxial lateral rods each projecting laterally from a lever, each intended to rest on a hook, and a suitable clamping screw. to cause the pivoting of the levers about the axis of the rods between a position in which the bearing surface of the levers is in contact with the anode rod and urges it towards the anode frame substantially perpendicular thereto and a release position in which the bearing surface of the levers does not exert no pressure on the anode rod. The geometry and the constituent material of at least one hook, a lever and / or a lateral rod of the connector are able to allow, when tightening the screw for holding and connecting the anode rod, an elastic deformation sufficient of the holding device relative to the anode frame so that the holding device can, by at least partial elastic return to its rest position, compensate for any change in the position of the anode rod relative to the anode frame and continue thus to ensure a firm hold of the anode rod against the anode frame.

Unlike the prior art, this device also makes it possible to avoid the use of additional specific parts (roller, spring, washer) that would have to be assembled to the others and regularly changed.

The connector and / or the hook may be in accordance with those previously described.

According to one possible embodiment, the width L _C of the connector body is less than the width L _TA of the anode rod, and for example L _C <0.8 L _TA .

• placer la tige d'anode entre deux crochets fixés au cadre anodique ;
• prévoir un connecteur comprenant:
  1. a) un corps comportant au moins une partie mobile comprenant une face d'appui, ladite partie mobile se déplaçant de telle sorte que la dite face d'appui exerce une pression sur la tige d'anode, en suivant une direction sensiblement perpendiculaire à la surface de contact du cadre anodique;
  2. b) un couple de protubérances dépassant chacune latéralement dudit corps, orientées globalement perpendiculairement à ladite direction, étant destinées à reposer chacune sur un crochet fixé au cadre anodique, de part et d'autre de la tige d'anode;
  3. c) et un actionneur apte à provoquer le déplacement de ladite partie mobile pour l'amener entre une position de serrage, dans laquelle ladite face d'appui est en contact avec la tige d'anode et la sollicite vers le cadre anodique lorsque lesdites protubérances reposent sur lesdits crochets, et une position de desserrage, dans laquelle ladite face d'appui n'exerce pas de pression sur la tige d'anode;
• placer le connecteur sur les crochets, en faisant reposer chacune des protubérances latérales sur un crochet, le connecteur étant dans une position de desserrage;
• actionner l'actionneur pour amener la partie mobile vers une position de serrage.

Finally, according to another aspect, the invention relates to a method for holding and connecting an anode rod against an anode frame of an aluminum electrolysis cell, comprising the steps of:

• place the anode rod between two hooks attached to the anode frame;
• provide a connector comprising:
  1. a) a body comprising at least one movable part comprising a bearing face, said moving part moving so that said face pressing a pressure on the anode rod, in a direction substantially perpendicular to the contact surface of the anode frame;
  2. b) a pair of protuberances each protruding laterally from said body, oriented generally perpendicular to said direction, being intended to rest each on a hook attached to the anode frame, on either side of the anode rod;
  3. c) and an actuator adapted to cause the displacement of said movable part to bring it between a clamping position, in which said bearing face is in contact with the anode rod and urges it towards the anode frame when said protuberances rest on said hooks, and a release position, wherein said bearing face does not exert pressure on the anode rod;
• placing the connector on the hooks, resting each of the lateral protuberances on a hook, the connector being in a release position;
• actuating the actuator to move the movable portion to a clamping position.

In this method according to this aspect of the invention, the actuator is actuated to cause sufficient elastic deformation of at least one hook and / or at least a portion of the connector so that said connector, by elastic return at least partially said hook and / or said portion of the connector to its rest position, remains in contact with said anode rod and thus continues to ensure a firm hold of said anode rod against said anode frame.

• placer la tige d'anode entre deux crochets fixés au cadre anodique ;
• prévoir un connecteur comprenant un corps comportant deux leviers présentant au moins une face d'appui, deux tiges latérales sensiblement coaxiales dépassant chacune latéralement d'un levier et une vis de serrage ;
• placer le connecteur sur les crochets, en faisant reposer chacune des tiges latérales sur un crochet, le connecteur étant dans une position desserrée dans laquelle la face d'appui des leviers n'exerce pas de pression sur la tige d'anode ;
• actionner la vis de serrage pour provoquer le pivotement des leviers autour de l'axe des tiges vers une position de serrage dans laquelle la face d'appui des leviers est en contact avec la tige d'anode et la sollicite vers le cadre anodique sensiblement perpendiculairement à celui-ci.

In particular, this aspect of the invention relates to a method of holding and connecting an anode rod against an anode frame of an aluminum electrolysis cell, comprising the steps of:

• place the anode rod between two hooks attached to the anode frame;
• providing a connector comprising a body having two levers having at least one bearing face, two substantially coaxial lateral rods each protruding laterally from a lever and a clamping screw;
• placing the connector on the hooks, resting each of the lateral rods on a hook, the connector being in a loose position in which the bearing surface of the levers does not exert pressure on the anode rod;
• actuating the clamping screw to cause the pivoting of the levers about the axis of the rods to a clamping position in which the bearing surface of the levers is in contact with the anode rod and urges it towards the anode frame substantially perpendicularly to this one.

The clamping screw is actuated to cause sufficient elastic deformation of at least one hook, a lever and / or a lateral rod of the connector relative to the anode frame so that said hook, lever and / or said lateral rod can, by at least partial springback to its rest position, compensating for any change in the position of the anode rod relative to the anode frame and thus continuing to ensure a firm hold of the anode rod against the anode frame, the geometry and the constituent material of said hook, said lever and / or said lateral rod being chosen so as to allow such elastic deformation and such elastic return.

The connector and / or the hook may be in accordance with those previously described.

• La figure 1 est une vue en perspective d'une cellule d'électrolyse typique destinée à la production d'aluminium ;
• La figure 2 est une vue en perspective d'une tige d'anode plaquée contre un cadre anodique par un dispositif de maintien et de raccordement selon un premier mode de réalisation de l'invention ;
• Les figures 3 et 4 sont des vues latérales de la tige d'anode et du dispositif de la figure 2 respectivement en position desserrée et en position de serrage ;
• La figure 5 est une vue de dessus de la tige d'anode et du dispositif de la figure 2, montrant schématiquement, en pointillés, l'axe des tiges latérales et, partiellement, le corps du connecteur en position déformée ;
• Les figures 6 et 7 sont des vues en perspective et latérale d'un crochet selon un autre mode de réalisation de l'invention ;
• La figure 8 est une vue en perspective d'un connecteur selon encore un autre mode de réalisation de l'invention ; et
• La figure 9 est une vue latérale d'un connecteur selon encore un autre mode de réalisation de l'invention.

For a good understanding, the invention is again described below with reference to the accompanying figures showing, by way of non-limiting examples, several possible embodiments of the invention.

• The figure 1 is a perspective view of a typical electrolysis cell for aluminum production;
• The figure 2 is a perspective view of an anode rod pressed against an anode frame by a holding and connecting device according to a first embodiment of the invention;
• The figures 3 and 4 are side views of the anode rod and the device of the figure 2 respectively in the released position and in the clamping position;
• The figure 5 is a top view of the anode rod and the device of the figure 2 , schematically showing, in dashed lines, the axis of the lateral rods and, partially, the body of the connector in the deformed position;
• The Figures 6 and 7 are perspective and lateral views of a hook according to another embodiment of the invention;
• The figure 8 is a perspective view of a connector according to yet another embodiment of the invention; and
• The figure 9 is a side view of a connector according to yet another embodiment of the invention.

As illustrated in figure 1 an electrolysis cell 1 comprises a tank 2 capable of containing the liquid metal and the electrolyte bath, and a superstructure 3 comprising a fixed gantry 4 and a movable metal anode frame 5. The electrolysis cell 1 also comprises anodes 6 provided with a metal rod 7 for fixing and electrical connection of the anodes 6 to the anode frame 5. Each anode rod 7 is connected to the anode frame 5 by a holding device and connection. This device comprises two hooks 8 fixed to the anode frame 5, substantially at the same height, and between which the anode rod 7 is intended to be placed, as well as a connector 9.

The connector 9 firstly comprises a body comprising two levers, namely an upper lever 10 and a lower lever 11, each having two lateral flanges 12a, 12b, 13a, 13b. The flanges are here substantially identical. The two flanges of the same lever are joined firstly in the front by a shoe 14, at least part of which forms the bearing face of the levers 10, 11 is intended to exert pressure on the anode rod 7 towards the anode frame 5, and secondly at the rear by a nut 15, the two nuts 15 having substantially the same axis 16. In the zone before the body, the lower lever 11 is typically partially placed between the two flanges 12a, 12b of the upper lever 10.

The connector 9 also comprises two lateral rods 17a, 17b, substantially cylindrical and of the same axis 18, projecting from one of a first side and the other of the second side of the connector 9, in the front zone of the body. According to one possible embodiment, the two lateral rods 17a, 17b consist of a single rod passing through the body of the connector 9 and protruding laterally on either side of said body. The lateral rods 17a, 17b are intended to rest each on a hook 8.

Finally, the connector 9 comprises a clamping screw 19 engaged in the nuts 15 and having two threaded zones with opposite pitch each cooperating with a nut 15. Thus, the rotation of the screw 19 about the axis 16, by a corresponding clamping member cooperating with the head of the screw, causes the levers 10, 11 to pivot about the axis 18 of the lateral rods 17a, 17b, between a clamping position in which the two nuts 15 are spaced apart. the other ( figure 4 ) and a loosened position in which the two nuts 15 are substantially joined ( figure 3 ).

The connection of the anode rod 7 to the anode frame 5 is as follows: the anode rod 7 is placed between the two hooks 8 already attached to the anode frame 5, then the connector 9 is placed on the hooks 8, by resting each of the lateral rods 17a, 17b in the recess 8a of a hook 8, the connector 9 being in the loosened position. In this position, the bearing surface of the levers 10, 11 exerts little or no pressure on the anode rod 7 ( figure 3 ). Then the clamping screw 19 is actuated to cause the levers 10, 11 to pivot towards the clamping position. In the the clamping position, the bearing surface of the levers 10, 11 is in contact with the anode rod 7 and urges it towards the anode frame 5, substantially perpendicular thereto, thus ensuring the maintenance and connection of the rod anode 7 to the anode frame 5 ( figure 4 ).

The holding and connecting device is designed to ensure an excellent clamping of the anode rod 7 against the anode frame 5 at any time, even if the anode rod 7 is to move relative to the anode frame 5. This is achieved in the following way: on assembly, the clamping screw 19 is actuated until sufficient elastic deformation of at least one element of the device (hook, lever, lateral rod) with respect to the anode frame 5 Thus, by at least partial springback to its rest position, this element - or these elements - can compensate for any change in the position of the anode rod 7 with respect to the anode frame 5 and the device can thus continue to maintain the anode rod 7 against the anode frame 5.

According to a first embodiment, illustrated on the Figures 2 to 5 it is the lateral rods 17a, 17b of the connector 9 which provide this elastic effect.

In this embodiment, the width Le of the body of the connector 9 is relatively small compared to the width L _TA of the anode rod 7. Consequently, since the hooks 8 are placed on either side of the rod anode 7 and close thereto, the distance L between the body of the connector 9 and the bearing zone 20 of a lateral rod 17a, 17b on the corresponding hook 8 is relatively large. Due to this important cantilever, when tightening the screw 19, the lateral rods 17a, 17b can deform as shown schematically on the figure 5 , the axis 18 of the lateral rods 17a, 17b curving causing the body of the connector 9 to move away from the anode frame. The diameter D of the lateral rods 17a, 17b and the elastic limit of their constituent material are chosen in order to allow a sufficient deformation of the lateral rods 17a, 17b, that is to say the storage in the lateral rods 17a, 17b of a sufficient amount of mechanical energy that can be restored in case of modification of the position of the rod 7. In this case, the lateral rods 17a, 17b return at least partially to their rest position, and there still exists a clamping force of the anode rod 7 against the anode frame 5.

• le diamètre D des tiges latérales 17a, 17b est compris ente 45 et 65 mm, par exemple 57 mm ;
• le matériau constitutif des tiges latérales 17a, 17b est un acier dont la limite élastique est de l'ordre de 1040 N/mm² ;
• largeur Le du corps du connecteur 9 comprise entre 90 et 120 mm ;
• la distance L est comprise entre 95 et 115 mm pour une tige d'anode de largeur L_TA = 140 mm et entre 130 et 165 pour une tige d'anode de largeur L_TA = 220 mm.

According to one possible realization:

• the diameter D of the lateral rods 17a, 17b is comprised between 45 and 65 mm, for example 57 mm;
• the constituent material of the lateral rods 17a, 17b is a steel whose elastic limit is of the order of 1040 N / mm ² ;
• width of the connector body 9 between 90 and 120 mm;
• the distance L is between 95 and 115 mm for an anode rod of width L _TA = 140 mm and between 130 and 165 for an anode rod of width L _TA = 220 mm.

The same connector 9 is used for all the anode rods whose width L _TA is between 140 and 220 mm, which corresponds to 90% of the applications. Thus, since the width Le of the body of the connector 9 is constant, the cantilever (distance L), and therefore the reserve of mechanical energy, are all the more important than the width L _TA of the rod of anode 7 is large.

With these values, and for a force of 16 tons (8 tons on each hook 8), it is possible to obtain a displacement d of the connector body 9 of at least 0.8 mm for an anode rod 7 with a width of 140 mm and at least 1.8 mm, or even more than 3 mm, for an anode rod 7 with a width of 220 mm, which corresponds to variations greater than 300% and 400%, respectively, with respect to the prior art. for the same diameter of the lateral rods 17a, 17b. The connector 9 shown on the figure 5 is symmetrical, but other structures could be envisaged in which one of the two lateral rods 17a, 17b would be longer and / or would deform more than the other.

According to one possible embodiment, the pad 14 formed on the levers 10, 11 is made of an elastically deformable material. Under the effect of the tightening of the screw 19, the pad 14 is compressed between the lever 10, 11 corresponding and the anode rod 7 and can, if necessary, return at least partially to its rest position and continue to exercise on the anode rod 7 the effort required for its connection and its correct retention against the anode frame 5.

According to another embodiment, illustrated on the Figures 6 and 7 it is the hooks 8 that provide the elastic effect.

The hook 8 comprises a fastening base 21, extended by a carrier body 22 whose upper 23 and lower 24 edges are substantially parallel, and a curved end portion 25 defining a recess 26 for receiving a lateral rod 17a 17b, and whose free end edge 27 is substantially perpendicular to the lower edge 24 of the carrier body 22.

The hook 8 is welded at its base on a base 28 provided with two recesses 29 for fastening by screwing on the anode frame 5. Positioning means 30 are furthermore provided on a lateral face of the hook 8 intended to be opposite the anode rod 7 for guiding and positioning the anode rod 7 between the hooks 8.

The height h22 of the carrier body 22 is substantially constant and between 60 and 85% of the height h21 of the base 21. For example, h21 is of the order of 135 mm and h22 of the order of 100 mm.

According to one possible embodiment, the hook 8 is made of steel and has a thickness e less than 18 mm, for example 15 mm. The hook 8 may also include localized areas whose thickness is less than the overall thickness e of the hook 8.

The hook 8 thus has a greater capacity for elastic deformation than the hooks of the prior art. Thus, for a force of 16 tons (8 tons on each hook 8), the displacement of the recess 26 of the hook 8 in the direction of the force, which is substantially horizontal, is at least 20% greater than the displacement obtained with the known hooks. If the anode rod 7 changes position, the hook 8 may, by at least partial restitution of the mechanical energy that it has stored by deforming elastically, continue to ensure proper maintenance of the anode rod 7 against the anode frame 5. According to another embodiment, illustrated on the figure 8 it is the levers 10, 11 which provide the elastic effect.

The two lateral flanges 12a, 12b of the upper lever 10 are substantially identical and each have a notch 31 made from their upper edge, to the front. The two lateral flanges 13a, 13b of the lower lever 11 are substantially identical. They each have an indentation made from their lower edge, towards the front, and are placed between the lateral flanges 12a, 12b of the upper lever 10, so that the notches 31 are substantially opposite and define a housing adapted to receive the rods. lateral 17a, 17b (or a single through rod) substantially horizontally. The four flanges have substantially the form of question marks placed in pairs in an inverted position relative to each other. As a variant, only the lateral flanges 12a, 12b of the upper lever 10 or only the lateral flanges 13a, 13b of the lower lever 11 comprise such an indentation, the elastic effect then resulting from the lever whose flanges comprise the notch. In one embodiment of this variant, illustrated in Figure 8 , the lateral rods 17a, 17b are arranged in the In another embodiment of this variant, the lateral rods 17a, 17b pass through the lateral flanges 12a, 12b, typically near the hollow of the indentations 31; in this case, the indentations 31 are shallower than in the previous embodiment.

Due to the indentation 31, each flange 12a, 12b, 13a, 13b comprises two branches 32, 33 spaced apart from each other in a direction perpendicular to the anode frame 5. The flanges thus have an ability to elastic deformation perpendicular to the anode frame 5, by bringing the two branches 32, 33 closer to one and the same notch 31.

Finally, according to another embodiment, illustrated on the figure 9 , the skates of Figures 2 to 5 are in the form of elastic tabs 34 folded on themselves.

At rest, the two branches 35, 36 of a tab 34 are spaced from each other. When clamping the connector 9 against the anode rod 7, the two branches 35, 36 are brought closer together to become joined by elastic deformation. If the anode rod 7 changes position, the two branches 35, 36 will return to their rest position and, by elastic effect, will continue to urge the anode rod 7 towards the anode frame 5.

Of course, it is possible to combine two or more of the previously described embodiments to obtain a capacity for elastic deformation, and thus compensation movements of the anode rod even more important.

It goes without saying that the invention is not limited to the embodiments described above by way of example but that it encompasses all variants.

Claims (27)

1. Connector (9) for holding and connecting an anode rod (7) in contact with an anode beam (5) of an aluminium electrolytic cell (1), comprising:

   - a body comprising at least one mobile part (10, 11) comprising a bearing face (14), the said mobile part moving such that the said bearing face applies pressure on the anode rod (7), along a direction (D) substantially perpendicular to the contact surface of the anode beam (5);

   - a pair of substantially axial lateral protuberances (17a and 17b) each projecting beyond the sides of the said body, oriented substantially perpendicular to the said direction (D) and each of them being designed to rest on a hook (8) fixed to the anode beam (5), on each side of the anode rod (7);

   - and an actuator (19) that can displace the said mobile part (14) to bring it between a clamping position in which the said bearing face (14) is in contact with the anode rod (7) and forces it towards the anode beam (5) when the said lateral protuberances (17a and 17b) rest on the hooks (8), and a release position in which the said bearing face does not apply any pressure on the anode rod;

   characterised in that the said connector at least partially has a geometry and / or is at least partially composed of a material such that, when the said actuator brings the mobile part into the clamping position, the said connector is elastically deformed sufficiently so that, if there is a change in the position of the anode rod (7) with respect to the anode beam (5), the said connector remains in contact with the said anode rod due to its at least partial elastic return towards its unstressed position, and thus continues to hold the said anode rod firmly in contact with the said anode beam.
2. Connector (9) according to claim 1, characterised in that it comprises at least one part capable of storing sufficient elastic deformation energy to cause a large displacement, typically greater than 0.6 mm, of the bearing face towards the anode beam, when the clamping force is released.
3. Connector (9) according to claim 1, characterised in that it comprises at least one part capable of storing sufficient elastic deformation energy to compensate for angular displacement of the anode rod with the vertical of at least 0.15° and preferably at least 0.3°.
4. Connector (9) according to claim 1, characterised in that the part of the connector capable of storing a large elastic deformation is made from a material with a yield stress greater than 1000 N/mm2, and is typically a metal and particularly steel.
5. Connector according to claim 1, comprising:

   - a body comprising two levers (10, 11) intended for applying a pressure on the anode rod (7) towards the anode beam (5) through at least one bearing face;

   - two substantially coaxial lateral rods (17a, 17b) each projecting laterally from the said body and each of them being designed to rest on a hook (8) fixed to the anode beam (5), on each side of the anode rod (7) ;

   - and a clamping screw (19) capable of making the levers (10, 11) pivot around the axis (18) of the lateral rods (17a, 17b) between a clamping position in which the bearing face of the levers (10, 11) is in contact with the anode rod (7) and moves it towards the anode beam (5) substantially perpendicular to the anode beam, and a release position in which the bearing face of the levers (10, 11) does not apply pressure on the anode rod (7);

   characterised in that the geometry of at least one lever (10, 11) and / or lateral rod (17a, 17b) of the connector (9) and the material from which it is made are capable of enabling sufficient elastic deformation of the connector (9) when the screw (19) is tightened to hold and connect the anode rod (7), so that if the position of the anode rod with respect to the anode beam is changed, the said connector remains in contact with the said anode rod due to its at least partial elastic return towards its unstressed position, and thus continues to hold the said anode rod (7) firmly in contact with the said anode beam (5).
6. Connector according to claim 5, characterised in that at least one lateral rod (17a, 17b) is made from a material for which the yield stress is more than 1000 N/m2, and in that the distance (L) between the body of the connector (9) and the bearing area (20) of this rod (17a, 17b) designed to rest on the hook (8) fixed to the anode beam (5), is sufficiently large to enable elastic deformation of the said rod (17a, 17b) and consequently a displacement of the body of the connector (9) substantially perpendicular to the anode beam (5), with an amplitude greater than 0.6 mm.
7. Connector according to claim 6, characterised in that at least one lateral rod (17a, 17b) is made of metal, particularly steel.
8. Connector according to either claim 6 or 7, characterised in that the distance (L) between the body of the connector (9) and the bearing zone (20) of the corresponding lateral rod (17a, 17b) is between 20% and 40% of the distance between bearing zones (20) of the two lateral rods (17a, 17b).
9. Connector according to one of claims 5 to 8, characterised in that at least one lever (10, 11) comprises at least one side plate (12a, 12b, 13a, 13b) with a recess (31) formed from its upper edge or its lower edge and defining two branches (32, 33) separated from each other in a direction perpendicular to the lateral rods (17a, 17b).
10. Connector according to claim 9, characterised in that the bottom of the recess (31) forms a housing in which a lateral rod (17a, 17b) will fit.
11. Connector according to one of claims 5 to 10, characterised in that the upper lever (10) comprises two substantially identical side plates (12a, 12b) and each is provided with a recess (31) formed from its upper edge, and in that the two side plates (13a, 13b) of the lower lever (11) are practically the same, each is provided with a recess (31) formed from its lower edge, the lower lever being placed between the side plates (12a, 12b) of the upper lever (10) such that the recesses (31) are substantially facing each other and define a housing in which the substantially horizontal lateral rods (17a, 17b) can fit.
12. Connector according to one of claims 5 to 11, characterised in that at least one lever (10, 11) comprises an elastic pad (14), at least part of which forms the bearing face of the said lever (10, 11) on the anode rod (7).
13. Connector according to claim 12, characterised in that the pad is in the form of an elastic tab (34) folded on itself.
14. Connector according to claim 13, characterised in that the elastic tab (34) is made from a metal, particularly steel.
15. Hook (8) designed to be fixed to the anode beam (5) of an aluminium electrolytic cell (1) to hold and connect an anode rod (7) placed on the side of the hook (8) in contact with the anode beam (5), and on which a connector (9) is intended to rest that can be actuated between a clamping position in which the connector (9) is in contact with the anode rod (7) and pulls it towards the anode beam (5) substantially perpendicular to the anode beam, and a release position in which the connector (9) does not apply any pressure on the anode rod (7), characterised in that the geometry of the hook (8) and the material from which it is made are such that, when the connector (9) is moved towards the clamping position, they enable a sufficient elastic deformation of the hook (8) with respect to the anode beam (5) so that the hook (8) can compensate for a possible change in the position of the anode rod (7) with respect to the anode beam (5), and thus continues to hold the said anode rod (7) firmly in contact with the said anode beam (5).
16. Hook according to claim 15, characterised in that it has an attachment base (21), a supporting body (22) for which the upper edges (23) and the lower edges (24) are substantially parallel, and a curved end part (25) .
17. Hook according to claim 16, characterised in that the height (h22) of the supporting body (22) is substantially constant and is between 60 and 85% of the height (h21) of the base (21).
18. Hook according to one of claims 15 to 17, characterised in that the supporting body (22) is made of steel and in that its thickness (e) is less than 18 mm.
19. Hook according to one of claims 15 to 18, characterised in that it comprises local areas for which the thickness is less than the general thickness (e) of the hook (8).
20. Device for holding and for the connection of an anode rod (7) in contact with an anode beam (5) of an aluminium electrolytic cell (1), comprising:

    - two hooks (8) fixed to the anode beam (5) and between which the anode rod (7) is intended to be placed;

    - a connector (9) comprising:

    a) a body comprising at least one mobile part (10, 11) comprising a bearing face (14), the said mobile part being displaced such that the said bearing face applies a pressure on the anode rod (7), along a direction (D) substantially perpendicular to the contact surface of the anode beam (5),

    b) a pair of protuberances (17a and 17b) each projecting laterally from the said body, globally oriented perpendicular to the said direction (D), each designed to rest on a hook (8), and

    c) an actuator (19) capable of causing displacement of the said mobile part to bring it between a clamping position in which the said bearing face is in contact with the anode rod (7) and forces it towards the anode beam (5) when the said protuberances rest on the said hooks, and a release position in which the said bearing face does not apply any pressure on the anode rod (7),

    characterised in that the said hooks and / or the said connector at least partially have a geometry and / or are at least partially formed from a material such that when the said protuberances are supported on the said hooks and the said actuator brings the mobile part into the clamping position, the said holding and connection device is elastically deformed sufficiently so that, if there is a change in the position of the anode rod (7) relative to the anode beam (5), the said connector remains in contact with the said anode rod due to its at least partial elastic return towards its unstressed position, and thus continues to hold the said anode rod firmly in contact with the said anode beam.
21. Holding and connection device according to claim 20 in which the said connector (9) comprises a body with two levers (10, 11) with at least one bearing face, two substantially coaxial lateral rods (17a, 17b) each being provided with a lever (10, 11) on the side, each of them being intended to rest on a hook (8), and a clamping screw that can pivot the levers (10, 11) about the axis of the rods (17a, 17b) between a clamping position in which the bearing face of the levers is in contact with the anode rod (7) and moves it towards the anode beam (5) substantially perpendicular to the anode beam, and a release position in which the bearing face of the levers (10, 11) does not apply any pressure on the anode rod (7);
    characterised in that the geometry of at least one hook (8), a lever (10, 11) and / or a lateral rod (17a, 17b) of the connector (9) and the material from which they are formed are such that, when the screw (19) for holding and connection of the anode rod (7) is tightened, the elastic deformation of the holding device with respect to the anode beam (5) is sufficient so that the holding device can compensate for a possible change in the position of the anode rod (7) with respect to the anode beam (5), by at least partial elastic return towards its unstressed position, and thus continues to keep the said anode rod (7) firmly in contact with the said anode beam (5).
22. Device according to claim 21, characterised in that it comprises at least one connector (9) according to one of claims 1 to 14 and / or one hook (8) according to one of claims 15 to 19.
23. Device according to either claim 21 or 22, characterised in that the width L_C of the body of the connector (9) is less than the width L_TA of the anode rod (7) .
24. Device according to claim 23, characterised in that L_C < 0.8 L_TA.
25. Method for holding and connection of an anode rod (7) in contact with an anode beam (5) of an aluminium electrolytic cell, comprising steps consisting of:

    - placing the anode rod (7) between two hooks (8) fixed to the anode beam (5):

    - providing a connector (9) comprising:

    a) a body comprising at least one mobile part (10, 11) comprising a bearing face (14), the said mobile part being displaced such that the said bearing face applies a pressure on the anode rod (7), along a direction substantially perpendicular to the contact surface of the anode beam (5),

    b) a pair of protuberances (17a and 17b) each projecting laterally from the said body, globally oriented perpendicular to the said direction (D), each designed to rest on a hook (8) fixed to the anode beam (5) on each side of the anode rod (7);

    c) and an actuator (19) capable of causing displacement of the said mobile part to bring it between a clamping position in which the said bearing face is in contact with the anode rod (7) and forces it towards the anode beam (5) when the said lateral protuberances rest on the said hooks, and a release position in which the said bearing face does not apply any pressure on the anode rod;

    - placing the connector (9) on the hooks (8), by making each of the lateral protuberances (17a and 17b) rest on a hook (8), the connector (9) being in a release position;

    - actuating the actuator to bring the mobile part into a clamping position;

    characterised in that the actuator is actuated to cause a sufficient elastic deformation of at least one hook and / or at least one part or the connector so that, due to the at least partial elastic return of the said hook and / or the said part of the connector towards its unstressed position, the said connector remains in contact with the said anode rod and thus continues to hold the said anode rod firmly in contact with the said anode beam.
26. Method according to claim 25 comprising steps consisting of:

    - placing the anode rod (7) between two hooks (8) fixed to the anode beam (5);

    - providing a connector (9) comprising a body comprising two levers (10, 11) with at least one bearing face, two substantially coaxial lateral rods (17a, 17b) each projecting laterally from a lever and a clamping screw (19);

    - placing the connector (9) on the hooks (8), making each of the lateral rods (17a, 17b) rest on a hook (8), the connector (9) being in a release position in which the bearing face of the levers (10, 11) does not apply any pressure on the anode rod (7);

    - actuating the clamping screw (19) to cause pivoting of the levers (10, 11) around the axis of the rods (17a, 17b) towards a clamping position in which the bearing face of the levers (10, 11) is in contact with the anode rod (7) and moves it towards the anode beam (5) substantially perpendicular to the anode beam;

    characterised in that the clamping screw (19) is actuated to cause a sufficient elastic deformation of at least one hook (8), one lever (10, 11) and / or one lateral rod (17a, 17b) of the connector (9) with respect to the anode beam (5) so that the said hook (8), the said lever (10, 11) and / or the said lateral rod (17a, 17b) can compensate for a possible change in the position of the anode rod (7) with respect to the anode beam (5), by at least partial elastic return towards its unstressed position, and thus continue to keep the said anode rod (7) firmly in contact with the said anode beam (5), the geometry of the said hook (8), the said lever (10, 11) and / or the said lateral rod (17a, 17b), and the material from which they are made, being chosen to enable such an elastic deformation and such an elastic return.
27. Method according to claim 26, characterised in that the connector (9) complies with one of claims 1 to 14 and / or in that at least one hook (8) complies with one of claims 15 to 20.

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