EP0620061B1 - Device for rapid changing and holding a side wall in a twin roll continuous casting machinen for casting a metallic product - Google Patents

Abstract

The continuous casting machine includes two contra-rotating rolls (1, 2) with parallel axes arranged opposite each other, with a certain spacing, and on the axial ends of which two side walls (5a) bear so as to define a casting space (3) between the rolls. The device for rapidly changing the side wall (5a) includes a small barrel (14) comprising fastening means (16) for at least two side walls (5) in positions resulting from one another by means of a rotation through a specific angle about the axis of the small barrel. Means for rotationally displacing the small barrel in steps having an amplitude corresponding to the specific angle of rotation make it possible to displace a replacement side wall (5b) from a standby position to a position occupied by the active side wall (5a) to be replaced. <IMAGE>

Description

The invention relates to the rapid replacement of a side wall of a continuous casting machine for a metal product comprising two counter-rotating cylinders.

Are known devices for continuously casting a metal product and in particular a thin metal strip whose mold is essentially constituted by two counter-rotating cylinders with horizontal and parallel axes arranged opposite with a spacing corresponding to the thickness of the product to be poured.

The liquid metal is poured into the casting space defined by the portions of the surfaces of the cylinders situated above a plane passing through the parallel axes of these cylinders and by lateral end walls, called "small faces" in support on the axial ends of the cylinders.

The small faces must be applied against the axial ends of the cylinders, so as to obtain an effective seal to prevent any leakage of molten metal.

It is also necessary to avoid or limit the solidification of the metal in contact with the side walls. For this purpose, it has been proposed to produce the side walls in a thermally insulating material, so as to prevent significant cooling of the molten metal in contact with them.

It has also been proposed to use side walls comprising a part made of thermally insulating refractory material inserted between the cylinders and placed between two metal plates in the form of ring portions, each applied against a flat front face of each cylinder.

In all cases, the side walls undergo wear during operation because they come into contact with the cast metal during solidification. and moving in the air gap of the cylinders, and with the edges of the cylinders in rotation.

It is therefore necessary to replace the used side walls with new walls, after a certain time of operation of the casting machine.

To replace the side walls, it is necessary to stop the casting by closing the outlet of the distributor located above the mold.

After closing the distributor, the casting continues until the mold is completely emptied. We then replace the small faces.

The small faces arranged on either side of the ends of the cylinders are supported by carriages mounted mobile on guide rails parallel to the axes of the cylinders and associated with devices for translational movement between an advanced service position, in which the active parts of the small faces are in contact with the cylinders and a withdrawn position out of service, in which the small faces are distant from the cylinders.

The new replacement small faces are mounted on the corresponding carriages, in the remote position of these carriages.

The carriages are then replaced in their advanced service position in which they bring into contact and maintain the small faces with the ends of the cylinders.

The casting can then be resumed by replacing the shutter of the distributor in its open position.

In reality, the time required to replace the small faces, from the closure of the distributor to its reopening for the restarting of the casting is generally very long (of the order of 20 to 45 minutes) and consequently, it it is necessary to completely drain the distributor before performing a replacement operation, liquid metal which can hardly be kept in the distributor during this time.

Before restarting the casting, it is therefore necessary to fill the distributor with liquid metal contained in a ladle.

Certain maintenance operations of the casting machine, for example the cleaning of the rolls or the change of the distributor can be carried out in masked time during the change of the small faces.

However, the need to replace the small faces after a certain period of continuous operation of the machine results in discontinuous overall operation with relatively long interruption times and results in a significant reduction in the productivity of the machine.

Until now, no device has been known for quickly changing the small faces of a casting machine which makes it possible to greatly reduce the reset time of the casting machine, that is to say the time elapsing between the closing the distributor before an operation to replace the small faces and reopening the distributor after changing the small faces, to obtain an almost continuous operation of the machine with interruptions of a limited duration, for example less than three minutes.

The object of the invention is therefore to propose a device for rapidly changing a side wall of a machine for the continuous casting of a metallic product comprising two counter-rotating cylinders with parallel axes arranged opposite one another with a certain spacing on the axial ends of which two side walls are supported, so as to delimit a casting space between the cylinders and comprising a carriage for moving the side wall, mounted movably on a support in the axial direction of the cylinders between an advanced position and a retracted position with respect to the cylinders, this device making it possible to reduce the reset time of the machine to a very small value to effect a change of side walls, so as to ensure almost continuous operation of the casting machine and increase the productivity of this machine.

• un barillet monté rotatif sur le chariot autour d'un axe perpendiculaire à l'axe des cylindres, comportant des moyens de fixation pour au moins deux parois latérales dans des positions se déduisant l'une de l'autre par une rotation d'un angle déterminé autour de l'axe du barillet, et
• des moyens de déplacement en rotation du barillet par pas d'amplitude correspondant à l'angle de rotation déterminé, de manière à déplacer une paroi latérale de remplacement d'une position d'attente à une position occupée par une paroi latérale en service à remplacer.

To this end, the device according to the invention further comprises:

• a barrel rotatably mounted on the carriage about an axis perpendicular to the axis of the cylinders, comprising fixing means for at least two side walls in positions deduced from each other by a rotation of an angle determined around the axis of the barrel, and
• means for rotationally moving the barrel in steps of amplitude corresponding to the determined angle of rotation, so as to move a replacement side wall from a standby position to a position occupied by a side wall in service to be replaced .

Another advantage of the device according to the invention is that it makes it possible to easily and without loss of time preheat the replacement side wall or walls before putting them into service.

In fact, we know that it is necessary to heat the small faces before they are put into service, to prevent the cast metal from freezing on contact. For this one can use burners acting either on the active face of the small faces, or on the rear face of these. In the first case, and in the device according to the prior art, it is difficult to carry out this preheating when the small face is in the service position, because there is a risk of damaging the cylinders by the flame of the burners. In addition, the preheating time is relatively long, which is incompatible with a quick replacement of the small faces. In the second case, there is less risk of damaging the cylinders, but the preheating time remains unacceptable, preheating is not done in good conditions because carried out on the side of the small face opposite to that which will be in contact with the metal sunk, and the support of the small face is made complicated.

Furthermore, preheating carried out before the placement of the small faces on their support would eliminate the above problems, but would force the operators to handle small faces brought to very high temperature, to fix them on their support, which would be very dangerous.

These problems can be solved by the device according to the invention by using preheating means acting on the side wall (s) on standby, after their installation on the barrel. Preheating can thus be done on the face of the wall which will then be in contact with the liquid metal, and therefore, the temperature of this face will be as high as possible before the side wall is put into service, which will be immediately operational. as soon as it is placed in the service position

In order to clearly understand the invention, a description will now be given, by way of nonlimiting example, with reference to the appended figures, an embodiment of a device for rapid change and for maintaining a side wall. according to the invention, in the case of a continuous casting machine for a thin strip of steel.

Figure 1 is a top view of a part of the casting machine and a change and holding device according to the invention and according to a first embodiment.

Figure 2 is a sectional view along 2-2 of Figure 1.

Figure 3 is a side elevational view along 3-3 of Figure 1.

Figure 4 is a longitudinal sectional view similar to the section of Figure 2, of a second embodiment of a device according to the invention.

FIG. 5 is a view in elevation and in partial section along 5-5 of FIG. 4.

Figure 6 is a longitudinal sectional view similar to the view of Figure 4, of an alternative embodiment of the device according to the second embodiment.

FIG. 7 is a front elevation view and in partial section along 7-7 of FIG. 6.

In Figure 1, we see a part of the casting installation consisting of two cylinders 1, 2 arranged with their horizontal and parallel axes and providing between them a space 3 of a small width corresponding substantially to the thickness of the strip steel which is poured between cylinders 1 and 2.

The cylinders 1 and 2 respectively comprise extensions 1a and 2a by means of which the cylinders 1 and 2 are rotatably mounted in bearings and driven in rotation in opposite directions, with respect to each other. The extensions can be mounted on the same side of the cylinders, as shown in FIG. 1, or on one side for one cylinder and on the other side for the other cylinder.

The cylinders 1 and 2 delimit between their lateral surfaces, above a horizontal plane passing through their axes at which the spacing 3 between the cylinders is the smallest, a casting space which is closed, at the ends longitudinal of the cylinders 1 and 2, by two side walls such that the wall 5 held against the cylinders 1 and 2 in the position of tightening and sealing by a quick change and holding device according to the invention generally designated by the reference 4.

The device for quickly changing and holding the side wall 4 according to the invention will be described, with reference to all of FIGS. 1, 2 and 3.

The device 4 comprises a support 6 resting by means of a base 6a on the floor of the casting machine and two lateral uprights 6b and 6c fixed by brackets on the base 6a and carrying at their upper part a longitudinal slide, respectively 7b and 7c consisting of two parts attached to each other and fixed by screws.

The lateral uprights 6b and 6c of the frame and the corresponding slides 7b and 7c are placed in the direction of the axis of the cylinders 1 and 2 or longitudinal direction, on either side of the vertical median plane of the casting space 3 .

A carriage 8 is mounted movable in translation in the longitudinal direction on the support 6, by means of the slides 7b and 7c, the carriage 8 comprising lateral guide elements 8b and 8c which are engaged between the two parts of the slides, respectively 7b and 7c.

As can be seen in FIG. 2, the carriage 8 has a through opening 9 at the level of which is fixed a column 10 with a vertical axis directed downwards inside the support 6, carrying at its lower end a bearing 11 to vertical axis. The support 6 also carries on its upper surface a crown 12 constituted by a taper roller bearing coaxial with the column 10 and the bearing 11.

A barrel 14 is rotatably mounted around the vertical axis of the column 10 of the support 8, via of the bearing 12 and of a tubular shaft 13 rotatably mounted inside the bearing 11.

The barrel 14 has a base 15 resting on the internal ring of the conical bearing 12 and side walls 16a, 16b and 16c resting on the base 15 and assembled together by welding along their edges at their upper parts, so as to be arranged according to three sides of a parallelogram. Each of the vertical walls 16a, 16b, 16c of the barrel 14 comprises means for fixing a side wall 5 such that the side wall 5a in service against the cylinders 1 and 2 and the walls 5b and 5c which may be constituted by walls new side in waiting position on the barrel 14.

The support 6 carries two jacks 17a and 17b for translational movement in the longitudinal direction of the carriage 8 carrying the barrel 14 on which the side walls are fixed.

Each of the jacks 17a and 17b has a body fixed on the support 6 and a rod connected to the rear end of the carriage 8.

The jacks 17a and 17b allow the carriage 8 carrying the barrel 14 to be moved between an advanced position towards the cylinders as shown in FIG. 1 and a retracted position in which the barrel 14 and the side wall 5 are distant from the surfaces of end of cylinders 1 and 2.

The tubular shaft 13 of the barrel 14 is secured, at its lower end, to a chain pulley 18.

The barrel 14 which is rotatably mounted on the support 8 around the vertical axis common to the bearings 11 and 12 can be rotated by a rotary hydraulic cylinder 19 fixed on a support 20 integral with the column 10. The cylinder 19 comprises a vertical rotary axis on which is fixed a chain pulley 21 which ensures the drive of the chain pulley 18 secured to the tubular shaft 13, by means of a chain 22 engaged on the toothed parts of the pulleys 18 and 21. The drive can thus be achieved by a belt.

The carriage 8 carries on its upper surface, a fixed stop 24 and the base 15 of the barrel 14 is crossed by openings such as 23a and 23b in which a movable stop such as 26 can be engaged.

In addition, the support 6 carries an indexing cylinder 25 having a vertical arrangement and comprising a rod at the end of which is fixed a blocking pin 25a.

When the carriage 8 has been placed in its retracted position thanks to the jacks 17a and 17b, the barrel 14 is sufficiently clear with respect to the cylinders 1 and 2, so that it can rotate around its vertical axis, so as to present a new side wall opposite cylinders 1 and 2.

A rotation of a quarter of a turn of the barrel 14 makes it possible to place the wall 5b opposite the cylinders, that is to say in the position previously occupied by the wall 5a.

The rotation of the barrel 14 by a quarter turn thus makes it possible to place a new side wall in a position of engagement with the end surfaces of the cylinders 1 and 2.

The movable stop 26 is placed in a position such that this stop comes into contact with the fixed stop 24 when the barrel has made a quarter turn in the desired direction (for example, considering FIG. 1, in the direction of the needles d 'a watch, to orient the wall 5b along the initial orientation of the wall 5a).

The contact between the movable stop 26 and the fixed stop 24 makes it possible to stop the rotation of the barrel after a quarter turn. In the case where only two small faces are mounted symmetrically on the barrel, the barrel may perform between two stop positions, half-turns alternately in one direction and in the other. In the case of more than two small faces, at least one of the stops is retractable.

The barrel 14 is immobilized and fixed in position by the pin 25a of the indexing cylinder 25 which is engaged in an opening of the base 15 of the barrel located in a position allowing the barrel to be indexed.

As can be seen, in particular in FIGS. 2 and 3, the small faces such as 5a, 5b and 5c which are made at least partially of refractory material have opposite circular edges corresponding to the edges of the cylinders 1 and 2 with which they come in touch. The refractory material is preferably inserted into a metal casing, forming a pre-assembled assembly called a cassette.

The small face 5a, visible in FIGS. 2 and 3, is fixed on a metal support 30a which is itself connected to the vertical wall 16a of the barrel by connecting means ensuring a certain latitude of movement of the small face 5a in the longitudinal direction, to ensure tightening against the end parts of the cylinders 1 and 2.

These connecting means comprise a set of thrust cylinders 31 fixed to the wall 16a, the rods of which are connected to the support 30a, at a set of points distributed over the surface of the small face, as it can be seen in FIG. 3.

The jacks 31 exert a thrust on the support 30a, in the longitudinal direction, in the direction of the ends of the cylinders 1 and 2, so as to apply the small face 5a in leaktight manner against the cylinders, when the barrel 14 and the carriage 8 are in their advanced position as shown in Figure 1.

The jacks 31 could be replaced by thrust springs interposed between the front surface of the wall 16a of the barrel and the rear surface of the support 30a.

The connecting means also comprise cylinders or return springs 32 connected to the support 30a, at its upper part and at its lower part, so as to exert on the cassette a return force, in the longitudinal direction, in a direction opposite to the force exerted by the support devices 31.

Displacement sensors 33 are also arranged between the wall 16a and the support 30a, so as to determine the displacements and the position of the support 30a, during the positioning of the small face 5a and during the use of the casting machine . The sensors 33 make it possible in particular to control the positioning and wear of the small face 5a.

The support means 31 and the return means 32 of the small face 5a, the active part of which comes into contact with the cylinders 1 and 2 ensure flexible fixing of the cassette which has a certain latitude of movement in the horizontal direction.

The support 30a of the small face 5a is supported on pins 34 which ensure its maintenance in the vertical direction and on lateral stops 35 which ensure its maintenance in the transverse direction, during casting.

We will now describe an operation for changing a side wall using the device according to the invention as shown in FIGS. 1, 2 and 3.

When wear of the active part of the side wall 5a has been detected by means of the displacement sensors 3 requiring replacement, the feed distributor of the ingot mold is closed by the cylinders and the small faces then the casting is continued until the mold is completely emptied.

The carriage 8 and the barrel 14 are then moved to a remote position remote from the cylinders 1 and 2, using the jacks 17a and 17b fixed on the support 6.

The position of the stops is checked, so as to cause the barrel to make a quarter turn in the desired direction, for example to place the small face 5b in a position facing the ends of the cylinders 1 and 2, at the place of the small face 5a.

The small face 5b is equipped with a new active part and has been preheated by a device (not shown) which may be, for example, a burner or a resistance heater by radiation.

The carriage 8 and the barrel 14 are then moved in the direction of the cylinders 1 and 2, until the active part 5b of the small face comes into contact with the ends of the cylinders to be held against the cylinders with a certain pressure, through the support devices 31.

The carriage 8 carrying the barrel 14 is clamped, at the level of the slides 7b and 7c, in its advanced position, by clamping cylinders 36.

During all the operations necessary to carry out the change of the small face, it is possible to carry out, in partially masked time, brushing of the end parts and of the table of the cylinders, in order to remove the particles for example of slag which may have stuck on its surfaces. This improves the quality of the product when restarting the casting.

It is possible, using the device according to the invention, to change side walls in a very short time, for example of the order of three minutes or less.

Due to the very short time required for changing the small face, it is possible to make the change without draining the distributor.

It is also possible to keep the cylinders in rotation during the change operations.

The various clamping and return cylinders of the cassette carrying the active part of the small face are supplied by a hydraulic block 37 placed inside the barrel 14, above the upper end of the column 13.

The cables and supply pipes of the hydraulic block 37 penetrate inside the column 13 and the barrel, by means of a rotary joint 38 fixed to the lower end of the carriage 8.

Finally, the means for guiding the cables and pipes for supplying the small face and the barrel are constituted by a cable-carrying chain 39 disposed on the upper part of the support 6.

In Figures 4 and 5, there is shown a quick change device according to the invention and according to a second embodiment.

The changing device designated as a whole by the reference 40 comprises a support 41 of longitudinal direction fixed to the floor of the casting machine and comprising vertical lateral uprights at the upper part of which are slides of longitudinal direction 42b and 42c. A carriage 43 is mounted movable in the longitudinal direction on the support 41, by means of external lateral parts of its base 43a.

The carriage 43 can be moved in the longitudinal direction on the support 41 by a hydraulic cylinder carried by the support 41, the rod 45 of which is connected to the carriage 43.

The carriage 43 comprises two vertical uprights 43b and 43c fixed by welding on the upper face of the base 43a.

A barrel 44 is rotatably mounted between the uprights 43b and 43c, by means of a tubular shaft 46 having a horizontal arrangement, the end portions of which are mounted in bearings carried by the uprights 43b and 43c respectively.

The shaft 46 constituting the central part of the barrel is integral with four walls 47a, 47b, 47c and 47d, by means of spacers 48.

Each of the walls 47a, 47b, 47c, 47d carries a cassette comprising a cassette support and the active part of a small face. The active parts of the small faces fixed on the walls 47a, 47b, 47c and 47d and the corresponding small faces are designated respectively by the references 50a, 50b, 50c and 50d.

The cassette supports on which the small faces 50a, 50b, 50c, 50d are fixed are themselves connected to the walls 47a, 47b, 47c, 47d, as described with regard to the wall 5a of the device shown in the figures 1, 2 and 3.

A rotary actuator 51 is fixed in an opening passing through the lateral upright 43b of the carriage 43. The axis of the actuator 51 carries a pulley 52 which makes it possible to drive in rotation, by means of a chain or a belt 54 , a second pulley 53 secured to the end of the tubular shaft 46 of the barrel 44.

The upright 43c of the carriage 43 carries an indexing jack 56 whose rod 56a can be engaged in an opening of a wall 57 integral with the tubular shaft 46 of the barrel 44. The indexing jack 56 makes it possible to block in the position of the barrel 44, after a rotation having brought the active part 50a of a small face opposite the cylinders.

The operation of the device shown in Figures 4 and 5 is practically identical to the operation described with regard to the device shown in Figures 1, 2 and 3, the active parts of the small faces 50a, 50b, 50c, 50d can be brought by successive rotations of a quarter turn, vis-à-vis the cylinders of the casting machine, when the carriage 43 is placed in the retracted position.

The differences between the devices of FIGS. 1, 2 and 3 and the device of FIGS. 4 and 5 relate to the direction of the axis of rotation of the barrel (vertical in the first case and horizontal in the second case) and to the presence , in the second case, four sides of the barrel for placing four cassettes carrying the active parts of four small faces.

It is quite obvious that in the case of the barrel device with vertical axis of FIGS. 1 to 3, it is also possible to place four small faces on four walls of the barrel instead of the three small faces described.

In Figures 6 and 7, there is shown an alternative embodiment of the quick change device shown in Figures 4 and 5, the corresponding elements in Figures 4 and 5 on the one hand and in Figures 6 and 7 on the other part having the same references, however with the sign ′ (prime) in the case of the elements of the device shown in FIGS. 6 and 7.

The device shown in FIGS. 6 and 7 comprises a longitudinal support 41 ′, the lateral uprights of which carry slides 42′b and 42′c at their upper part. A carriage 43 ′ is mounted movable in the longitudinal direction relative to the support 41 ′, by means of lateral parts of the base of the carriage 43′a engaged in the slides 42′b and 42′c. A cylinder whose rod 45 ′ connected to the carriage 43 ′ has been shown in FIGS. 6 and 7 makes it possible to move the carriage 43 ′ between an advanced position in the vicinity of the ends of the cylinders of a casting installation and a retracted position.

The carriage 43 ′ has lateral uprights 43′b and 43′c between which a barrel 44 ′ is rotatably mounted by means of a horizontal tubular shaft 46 ′.

The barrel 44 ′ has two parallel walls between them 47′a and 47′b each carrying a support cassette for the active part 50′a or 50′b of a small face of the casting machine.

The support cassettes of the small faces are connected to the corresponding walls 47′a and 47′b, in the same way as the support cassettes of the small faces 50a, 50b, 50c, 50d connected to the walls 47a, 47b, 47c and 47d of the barrel 44 shown in Figures 4 and 5.

The difference between the barrels of the devices shown in Figures 4 and 5 on the one hand and 6 and 7 on the other hand is that the barrel of the device of Figures 4 and 5 has four support walls of four small faces while the barrel of the device of Figures 6 and 7 has only two support walls of two small faces.

When the carriage 43 ′ and the barrel 44 ′ are in a retracted position relative to the cylinders of the casting machine, the barrel 44 ′ can be turned by half a turn, so as to reverse the position of the small faces 50 ′ a and 50′b.

Before carrying out the change of small face, it is possible, as previously, to preheat the small replacement face, before placing it by rotating the barrel, in a position facing the cylinders.

In the case of the replacement devices shown in FIGS. 1 to 3, 4 and 5 and 6 and 7 respectively, after replacing a small used face, it is possible to dismantle this small used face, after restarting the installation , the corresponding position on the barrel being accessible. The cassette is then mounted with a new active part on the corresponding wall of the barrel, and the small face is preheated in this position.

In all cases, the device according to the invention allows the side walls or small faces of the continuous casting machine to be changed very quickly.

The device according to the invention also makes it possible to carry out in a simple manner the preheating of the small faces before putting them in the service position against the rolls of the casting machine.

It also makes it possible to place the new replacement side walls on the barrel, during the operation of the casting machine.

The invention is not limited to the embodiments which have been described.

This is how the support, the carriage and the barrel as well as their means of movement can be produced in a manner different from that which has been described.

The barrel can have only two walls making it possible to set up two small faces or on the contrary a greater number of walls making it possible to set up more than two walls simultaneously on the barrel.

When the device includes preheating burners, it is advantageous, although not essential, for reasons of space, to place these burners parallel to the axes of the cylinders, by making them act on a replacement side wall located symmetrically with the side wall in service with respect to the axis of the barrel. The barrel may then have only two side walls arranged symmetrically, one being exchanged and preheated while the other is in service.

The invention applies not only to machines for casting strips between cylinders but also to machines for casting between cylinders of other metal products.

Claims (10)

1. Device for rapidly changing and holding in place a side wall of a machine for continuously casting a metal product, including two counterrotating rolls (1, 2) having parallel axes and arranged facing each other with a certain spacing, against the ends of which two side walls (5) bear so as to demarcate a casting space (3) between the rolls and including a carriage (8) for moving the side wall (5), this carriage being mounted so as to move on a support (6) in the axial direction of the rolls between a forward position and a set-back position with respect to the rolls, characterized in that it furthermore includes:

   - a barrel (14), mounted so as to rotate on the carriage (8) about an axis perpendicular to the axis of the rolls (1, 2) and provided with means (16) for fixing at least two side walls (5) in positions which can be derived from each other by a rotation through a defined angle about the axis of the barrel (14), and

   - means (18, 19, 20, 21, 22) for rotationally moving the barrel (14) in steps of amplitude corresponding to the said defined angle of rotation so as to move a replacement side wall (5b) from a stand-by position to a position occupied by an in-service side wall (5a) to be replaced.
2. Device according to Claim 1, characterized in that the barrel (14) is mounted so as to rotate about a vertical axis.
3. Device according to Claim 1, characterized in that the barrel (44) is mounted so as to rotate about a horizontal axis.
4. Device according to any one of Claims 1 to 3, characterized in that the means (16) for fixing the side walls (5) include, for each of the side walls, a support (30a) to which the side wall is fixed and means (31, 32, 34, 35) of linkage between the support of the side wall (5) and a plane wall (47) of the corresponding barrel.
5. Device according to Claim 4, characterized in that the barrel includes two plane walls (47'a, 47'b) parallel to each other, the positions of which are derived from each other by a rotation of one half-turn of the barrel about its axis.
6. Device according to Claim 4, characterized in that the barrel (14; 44) includes plane walls (16; 47) which are perpendicular in pairs and arranged as the faces of a parallelepiped, and the positions of which are derived from each other by a rotation of the barrel through a quarter of a turn.
7. Device according to Claim 6, characterized in that the barrel (14) includes three walls (16a, 16b, 16c) which are perpendicular in pairs.
8. Device according to Claim 6, characterized in that the barrel includes four walls which are perpendicular in pairs.
9. Device according to any one of Claims 1 to 8, characterized in that the means for rotationally moving the barrel (14) are associated with limit stops (24, 26) fixed to the carriage (8) and the barrel (14), so as to limit the rotational movement of the barrel to a step of amplitude corresponding to the defined angle of rotation.
10. Device according to Claim 1, characterized in that it includes heating means for preheating a replacement side wall (5b) in the stand-by position.

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