EP0974408A1 - Strip accumulator - Google Patents

Abstract

A band product accumulation unit including a mechanism for controlling the running of a band along a longitudinal direction, a fixed frame, a wrap-around carriage which is moveable on a track between a return position of minimum accumulation length and an out position of maximum accumulation length, wherein movement towards the out position increases a length while movement towards the return position decreases the length, the band being adapted to pass over at least one return member mounted on the wrap-around carriage so as to form at least an out portion and at least a return portion and defined by at least two spaced levels, a plurality of intermediate supporting members arranged along the track, each comprising at least one separating arm extending horizontally on at least one intermediate level disposed between two running levels of the band, each separating arm being fixed to a shaft which is pivotal about a vertical axis with respect to the fixed frame, a mechanism for controling the pivoting of each separating arm between an open position which allows the wrap-around carriage to move to the return position and a closed position wherein each separating arm extends transverse to and between the two running levels of the band, and a control mechanism for controlling the pivoting of each separating arm between the closed position and the open position.

Description

The subject of the invention is an installation accumulation of a product in a band comprising a trolley loopable longitudinally movable so as to make vary the accumulated length.

Such an installation, often called an accumulator horizontal, is described, in particular, in the document US-A-3,687,348.

Generally, a horizontal accumulator of this type includes means for controlling the movement of the strip, like a hoist, between fixed rollers and movable rollers mounted on a looping carriage which moves on a horizontal traffic lane, following a longitudinal axis of travel, so as to form several superimposed strands running in opposite directions.

The band that moves forward, for example, at a low level, passes on a deflection roller placed on a loopback carriage, returns to a higher level raised to a fixed deflection roller placed at the end upstream of the track, in the direction of travel of the strip, then comes back forward, goes back on a deflection roller mounted on another looping carriage, goes back on a third level, and so on, the band can be evacuated either forward, passing over the looping carriage, or, more generally, towards the rear, to be directed to an installation of treatment, for example pickling.

Inside the accumulator, the strip therefore forms several overlapping strands scrolling in directions opposite, respectively back and forth on several discarded levels. For example, in the layout of the document US-A-3,687,348, the strip scrolls over six levels in passing over three idler rollers. These are placed on three different carts but it is possible, in other provisions, to use a looping cart single bearing multiple deflection rollers.

The length of the accumulated strip is a function of the position of the looping carriage on the taxiway and the number of rollers carried by the carriage when uses a single carriage for multiple strands.

It is necessary to avoid contact between different strands of the tape that scroll in directions opposites and this is why the accumulator is associated with a plurality of intermediate support members, arranged on along the carriage lane and carrying separator arms that extend horizontally, each on an intermediate level, between two scrolling levels of the band.

However, the carriage must be allowed to pass to vary the accumulated tape length and that's why the support arms can pivot between a spread position, parallel to the scroll axis, which allows the passage of the carriage and an engaged position for which the separating arm extends transversely between the two scrolling levels of the strip.

In addition, to decrease the moving masses and the length of overhang of the separating arms, these can advantageously be divided into two parts placed on either side of the track and mounted respectively on two shafts arranged along the track and pivotally mounted each around a vertical axis. The pivoting of the two trees respectively in the direction of separation or half-arm engagement is controlled by displacement carriage on track, one way or the other. Through example, in the layout of document US-A-3,687,348 or from document DE-A-2150759, each separating half-arm is associated with a follower roller which cooperates with a device to cam mounted on the carriage and whose profile is determined to control the rotation of the separator arm around its tree, one way or the other depending on the direction of moving the carriage.

In the arrangement described in document DE-A-2150759, each half-arm carries a follower roller and is is therefore substantially in the axis of the strip when the arms are closed. As a result, the carriage carries two curved cams which each have a central part of the follower roller, placed substantially in the axis of the strip and gradually spreading to a part laterally offset in a position corresponding to the total opening of the arm.

Such a device does not make it possible to anticipate the door opening movement since this begins only when the central part of the carriage arrives at the two separating half-arms. However, in modern facilities the cart moves to a fairly high speed and, in the arrangement of document DE-A-2150759, we can fear a shock with a door not yet open or insufficiently open.

For this reason, in the layout of the document US-A-3687348, the two command follower rollers of the pivoting of each half-arm are mounted respectively on either side of the track, each at the end of a lever integral control in rotation of the arm. Each pebble follower cooperating with a cam formed on the side of the looping frame and which can project overhang forward of the carriage over a distance allowing anticipate the pivoting of the arm. However, the chassis lateral bearing each cam is quite fragile and the distance overhang is necessarily quite small. The deadline anticipation is therefore too low for speeds important carriage movement which are reached in modern facilities.

In addition, the ratio between the length that one can give to the cam to control the rotation of each half 90 ° arm and the necessary lateral deviation is quite small and the double curvature of the cam is therefore relatively accentuated. This results in high speed risks of shock and, through wear, an increase in clearances which, long, can lead to deterioration of equipment and Line stops too frequent.

In addition, it is necessary to avoid that the arms dividers open inadvertently in the event of contact with the moving band.

Therefore, each separating arm must be associated with a locking device which, in the provision of document DE-A-2150759, consists of a disc with two corresponding notches, respectively, in the closed and open position of the arms, and in which can engage a lock mounted on a lever repelled by a spring and cooperating itself with a second cam carried by the carriage. So, at the time where the follower roller engages in the first cam, the second cam controls the release of the remaining latch spread to allow rotation of the arm, the bolt entering the second notch at the end of the movement opening hours.

However, games may appear in the long run and we can fear an unlocking of the arm, in especially when the tape is running at high speed, a excessive force on the separating arm which can cause untimely pivoting thereof with risk of contact between the strands of the strip.

In addition, a synchronization fault can generate damage and shutdown of the installation in the event of collision of the looping carriage with a separating arm.

Furthermore, as already indicated, the modern installations operate at very high speed, the carriage being subjected to significant accelerations, and it is therefore necessary to reduce, as much as possible, the inertia of the devices used to control the pivoting and locking arms.

The invention aims to solve these different problems with rotation control means and separator arm locking allowing the accumulator to operate safely, the means used being particularly simple and having a low inertia.

The invention therefore relates, in general, to a accumulation system for a strip product comprising means for controlling the running of the strip along a longitudinal direction, a movable looping carriage on a track between a first length position minimum accumulation and a second length position maximum accumulation, respectively in a forward direction length increase and back decrease, said strip passing over at least one organ of return mounted on said carriage to form at least two strands back and forth respectively on at least two separated levels, a plurality of support members intermediate arranged along the track and comprising each at least one separating arm extending horizontally on at least one intermediate level between two levels of movement of the strip and pivotally mounted, around a vertical axis, on a fixed frame, and means of control of the pivoting of each separating arm between a open position for the passage of the looping carriage and a closed position for which the separating arm extends transversely between the two levels of scrolling of the strip, said control means being actuated, at passage of the looping carriage, by a tracking device cooperating with an active surface of a cam device mounted on the looping carriage.

According to the invention, the tracking device is offset from the pivot axis of the arm, in before it in the forward direction of movement of the carriage determining arm closure and device follower is connected to the means for controlling the rotation of the arm by a deformable articulated mechanism having two stable extreme positions respectively a first position corresponding to the open position of the arm and a second position corresponding to the closed position of the arm, said articulated mechanism being associated with means of removable retention of the mechanism with locking, at least in the second closed position of the separating arm, said removable holding means being actuated only by the follower device cooperating with the cam device at passage of the looping carriage, respectively for the blocking of the mechanism in the forward direction of the carriage and for release in the reverse direction.

In a preferred embodiment, each separator arm being fixed in rotation on a mounted shaft pivoting about a vertical axis, the control means of arm rotation include a first lever arm fixed in rotation on the vertical shaft, transversely to the pivot axis and having one end connected by a mechanism articulated to a second lever arm mounted pivoting on the fixed frame around a spaced vertical axis longitudinally of the pivot axis of the arm, forward of it and having one end on which is mounted a roller constituting the follower device cooperating with the cam device, the latter determinant, by displacement carriage, simultaneous rotation of the two lever arms connected by the articulated mechanism.

This mechanism preferably includes a third lever arm integral in rotation with the second arm of lever around the pivot axis thereof and having one end connected by a connecting rod to one end of the first lever arm, either of the two lever integral in rotation being connected by a spring of reminder of an attachment point placed on the fixed frame in a position diametrically opposite to a middle position of the follower roller, on both sides of which the second arm lever is biased by the return spring towards one either of two stable angular positions of the mechanism which determine, via the connecting rod and the third lever arm, maintaining the arm, respectively in the open position or in the position closed, as long as the roller is not stressed, by the passage in one direction or the other of the active surface of the cam device.

Particularly advantageously, in the second stable position of the articulated mechanism, the connecting rod is placed substantially in the extension of the third arm lever, so as to block the mechanism by knee brace effect, in the event of untimely action on the separating arm, the release of the toggle joint being produced only by action of the cam on the roller follower.

Each separating arm is advantageously consisting of two half-arms at each intermediate level carried respectively by two support shafts placed on either side of the track and rotatably mounted each around of a vertical axis. In this case, the cam device includes two active surfaces placed respectively from on either side of the longitudinal median plane of the strip and cooperating respectively, through a follower device, each with an articulated mechanism of control of the rotation of the corresponding shaft. So by rotation, in opposite direction, of the two shafts, the two half-arms pass from an open position allowing passage of the looping carriage, in a closed position for which the two half-arms are substantially aligned along a direction perpendicular to the longitudinal axis.

Other advantageous features of the invention which are the subject of the subclaims, will emerge from the following description of a mode of particular embodiment of the invention, with reference to annexed drawings in which:

Figure 1 shows, in partial side view, the trolley for looping an accumulator according to the invention.

Figure 2 is a partial top view representing the two stable positions of the mechanism Speak clearly.

Figure 3 shows, in perspective, a support in the engaged position of the arms, after passing the looping cart.

Figure 4 shows a perspective view of a support in the separated position of the arms, before passage of the looping cart.

Figure 5 shows, in perspective, a support in an intermediate position of the mechanisms articulated.

As indicated, the accumulator according to the invention is of the round-trip multi-strand type comprising a movable looping carriage 1 longitudinally on a track 3 and carrying several deflection rollers 2, on which the strip passes while forming several strands running in opposite directions on several separated levels which are defined by the rollers movable 2 and fixed rollers not shown, placed at the entrance to the storage facility, regularly spaced support being disposed between said strands of the tape.

In Figure 1, there is shown the carriage looping 1 after its passage in front of a support member A1. The strip arrives at a lower level, forming a strand B1 which passes over a first deflection roller 2a so as to go backwards along a strand B2. In the example shown, the two strands B1 and B2 are kept apart, by deflecting rollers 21, of a sufficient distance to allow the installation of a second roll of reference 2b.

Upper strand B2 passes over a deflection roller fixed not shown, placed at the entrance of the installation, ie to the left of the figure, and returns to the front along a strand B3 which passes over the second deflection roller 2b to go back following the fourth strand B4, the strip then being returned to a part of the factory, by example a pickling installation.

In the example shown, the strip therefore forms four strands, respectively two strands B1 and B3 which go in the forward direction of length increase accumulated, i.e. from left to right of the figure and two strands B2 and B4 which flow in the direction length decrease return, i.e. from the right towards the left.

Conventionally, to avoid contact between strands running in opposite directions, installation includes a number of support members intermediaries regularly spaced and arranged along the taxiway 3 of the loop truck 1.

In Figure 1 there is shown in detail a member support A1 and, for example, another support A2 placed at a certain distance from A1.

Each support member such as A1 comprises a set 8 of separating arms intended to interpose transversely between two strands running in directions opposites. Therefore, in the case of an installation to four strands B1, B2, B3, B4, set 8 includes three separating arms 4a, 4b, 4c placed at levels intermediate, respectively between strands B1 and B4, B4 and B3, B3 and B2. These separating arms are mounted on a common shaft 82 pivotally mounted on a fixed frame C, around of a vertical axis 80 and each extend horizontally in console. Each arm 4 preferably carries a roller 43.

As shown in Figures 3 and 4 in perspective, and according to a conventional arrangement making it possible to reduce the inertia of the moving masses, the support assembly 8 advantageously consists of two parts, each level separation comprising two half-arms 41, 41 'mounted respectively on two pivot shafts 82, 82 'placed on either side of taxiway 3 and which therefore each carry three half-arms, respectively 41, 41 '.

The support assembly 8 is mounted in a chassis fixed C consisting of a rigid structure, under construction welded, which spans taxiway 3 so to provide a passage for the looping carriage and the different strands of the tape.

The two support shafts 82, 82 'are mounted pivoting on chassis C, each around a vertical axis 80 and are associated with a means for controlling the rotation arms, actuated by a follower device 6 cooperating with a cam device 5 carried by the looping carriage 1 so as to control, as the carriage 1 passes, the rotation in the opposite direction to the shafts 82, 82 'carrying the half-arms dividers 41, 41 ', between an open position allowing the passage of the carriage, for which the two half-arms 41, 41 'are separated laterally and a closed position for which the two half-arms 41, 41 'are aligned at a level intermediate between the strands of the strip.

For example, Figure 3 shows, in perspective, the position of the two sets of arms 41, 41 ′ after the passage loop carriage 1 which moves from left to straight in the direction of increase in length accumulated. To simplify, the different strands of the strip are not shown in the perspective figures. We sees that in the closed position shown in the figure 3, the two half-arms 41, 41 ′ carried respectively by the two shafts 82, 82 'extend transversely to the direction of travel of the strip, i.e. at the axis longitudinal of track 3, and are substantially aligned.

When the loop carriage 1 goes back in the backward direction, i.e. to the left of the figure, to reduce the accumulated length, the arms 41, 41 'must move away in the open position, to allow its passage.

In the provision of document US-A-3687348, the follower layout is mounted on the side of the track circulation, at the end of a lever arm fixed on the arm pivot shaft.

In this way, the tracking device does not interfere with the passage of the looping carriage and, to anticipate opening of the arms, the control cam is provided on a lateral chassis which extends in overhang from the rear end of the loopback carriage. However, as as indicated above, the overhang distance is necessarily limited, and the anticipation time is therefore rather short.

In the arrangement according to the invention, on the contrary, the follower is separated from the control lever of the rotation of the arm and connected to it by a mechanism articulated whose length can be determined according to the anticipation period that one wishes to obtain.

In the example shown, each level, two half-arms 41, 41 'controlled by two follower devices 6, 6 'which engage, respectively in two cam devices 5, 5 'carried by the carriage loop 1 to control the opening or closing of half-arm 41, 41 '.

In Figures 1 and 2, we see that the device follower 6 is mounted on the side of the support frame C and offset by a distance L in front of the pivot axis 80 separating arms 4 in the forward direction of the carriage, this is to the right of the figure, the control lever 81 being connected to the follower device 6 by a mechanism articulated 7.

Figure 4 shows, in perspective, the position of the arm after the carriage 1 has passed from the right to the left in the backward direction of decreasing the length accumulated. Conversely, from the position shown in FIG. 4, the looping carriage 1 can return to the right in the forward direction, to increase the length of accumulated band, passing between the half-arms 41, 41 'of which closing is controlled, after passage of the carriage 1, by the two cam devices 5, 5 '.

The length of the cam 5 is of the same order as the distance L between the follower device 6 and the corresponding pivot control 8.

Thus, in the forward direction, the front part 54 of the cams 5 engages in follower rollers 61, 61 'at the time where the rear of the carriage 1 is at the level of the shafts of pivot 82, 82 'and the cams 5, 5' therefore control the closing of the arms 41, 41 ′ after the passage of the carriage 1.

In the backward direction, the arms 41, 41 'are closed and the rear part 53, 53 'of each cam 5, 5' engages first on the roller 61, 61 'offset in front of the shaft of pivot 82, 82 ', from distance L. The movement opening of the arms 41, 41 ′ begins at this moment and is therefore completed when the carriage 1 arrives at the axes 80, 80 ', the rollers 61, 61' then being at the outlet 54, 54 'of cams 5, 5'.

The offset distance L can be greater than in the provisions of the state of the art since it depends only on the length to be given to the 7. As a result, as the figures show, the variation in curvature of cam 5 is much more progressive and there is less risk of jolts even at very high speed, wear of the devices also being scaled down.

As noted, since the tape scrolls at high speed, it is necessary to order opening and closing the separator arms with a great security to avoid any deterioration. In this indeed, according to the invention, a mechanism is used particular which allows, by auto-blocking to avoid a untimely rotation of the separating arms.

Since the different elements constituting respectively the separating arms 4, the means of pivot 8, the actuator device 5, the device follower 6 and the articulated mechanism 7, are symmetrical by relative to the longitudinal axis of the looping carriage 1 and track 3, the following description will be made only in reference to the half shown in Figure 2.

Similarly, to simplify the description, the whole of each separating half-arm 41 carrying a roll of support 43 will be designated by reference 4.

The pivoting of each separator assembly 8 is controlled by an articulated mechanism 7 actuated by the follower device 6 which slides along a surface active 51 of the cam device 5. This is carried out under the shape of a U-section rail with a profile approximately in S, with two ends 53 and 54 placed at different distances from the longitudinal axis of track 3 and connected by a part 52 with double curvature.

The active surface 51 is profiled so that the rear end 53 oriented towards the fixed rollers is closer to the longitudinal axis of the carriage 1 than the front end 54 turned on the opposite side, towards the movable rollers 2.

As noted, due to the offset (L) fairly large between the axis 80 of rotation of the arms 4 and the follower device 6, the radii of curvature of the part central 52 can be large enough to get a progressive and shock-free change of the roller position 61 with respect to the longitudinal axis of the carriage 1, even when it travels at high speed on track 3.

The rotation of the arm support shaft 82 separators 4 is controlled by a first lever arm 81 stalled in rotation on the shaft 82 and connected by the mechanism articulated 7 to the follower device 6 which includes a roller 61 mounted at the end of a second articulated lever arm 62, around a vertical axis 60, on the fixed frame C.

According to the invention, the first lever arm 81 of control of the rotation of the separating arms 4 is connected by a connecting rod 73, articulated at its ends, to a third lever arm 72 which is integral in rotation, around the axis 60, of the second lever arm 62 for supporting the roller follower 61.

Normally, the two lever arms 62 and 72 are aligned and form a single lever 70 articulated on the axis 60.

The assembly thus forms an articulated mechanism 7 having two stable positions shown schematically on the FIG. 2, respectively a position M3 corresponding to the arm spacing position M1 4 and an M4 position corresponding to the M2 engagement position of the arms 4 (figure 2).

As indicated, when moving in the return direction of carriage 1, i.e. from right to left in Figures 1 and 2, the follower roller 61 penetrates in the rear end 53 of the rail 51 and follows the profile in S of it to come out through the front end 54 which is further from the longitudinal axis of track 3. The roller 61 thus controls the rotation of lever 70, from from position M4 shown in solid lines, up to the position M3 shown in dotted lines, the arm 41 passing from the closed position M2 to the open position M1.

The arm 62 of the lever 70 carrying the roller 61 is connected by a return spring 74 to a fixed attachment point 9 arranged on the frame C and placed, with respect to the axis 60, in a position diametrically opposite to a position middle M5 of arm 62. In this way, arm 62 is held applied by spring 74 against either of two fixed stops, respectively a stop 64 corresponding to the arm engagement position M4 and a stop 63 corresponding to the arm spacing position M3. The possibility of stretching the spring 74 allows the passage from one position to another, but only under the action of the follower roller 61 cooperating with cam 51.

Furthermore, according to another characteristic particularly advantageous, the lengths and orientations of the different parts of the articulated mechanism 7 are determined so that in the closed position M4, the arm 72 of the lever 70 is substantially aligned with the connecting rod 73. Preferably, the stop 64 is adjustable so that the joint 75 between the connecting rod 73 and the lever arm 72 slightly exceeds the position alignment. The whole thus forms a sort of knee brace with self-locking effect.

Indeed, when the half-arm 41 is in the M2 engaged position between two strands of the strip, the articulated mechanism 7 is in position M4. A untimely action, for example contact with the tape, tends to rotate the first lever 81 secured to the shaft 82 in the opening direction of the half-arm 41 and determines a thrust on the rod 73 which is collected by the arm 72 of the lever 70, the other arm 62 of which is blocked, in the corresponding direction, by the stop 64. We obtain thus, in the absence of action of the cam 51 on the roller 61 a self-locking mechanism that holds the half-arm 41 in the closed position.

Conversely, in the separated position M1 shown in dotted lines in FIG. 2, the articulated mechanism 7 is maintained in a stable position M3 by the spring 74 which applies the arm 62 against the stop 63. A self-locking effect is not, however, necessary in this position since the arm 41 is open.

The invention therefore makes it possible to obtain stability certain of the positions M1 and M2 of the separating arms 4 all avoiding the use of additional safety devices locking and unlocking.

Of course, the invention is not limited to details of the embodiment which has just been described in title of simple example.

In particular, the installation was described in the usual case where two half-arms are used at each level aligned to reduce the inertia of moving parts but it would obviously be applicable to installations using a single arm extending over the entire width of the strip and then controlled by a single tracking device 6 and a single cam 5 placed on the same side of the frame C and of carriage 1.

On the other hand, the arrangement of the looping carriage and different strands B1, B2, B3, B4 of the strip allowing a variation in the accumulated length could be different. Similarly, the articulated mechanism 7 could be done differently. The layout shown has, however, the advantage of great simplicity and can also be easily adapted to installations existing.

The reference signs inserted after the technical characteristics mentioned in the claims are intended only to facilitate the understanding of them and in no way limit them the scope.

Claims (7)

Installation for accumulating a product in a strip (B) comprising means for controlling the movement of the strip (B) in a longitudinal direction, a looping carriage (1) movable on a track (3) between a first position of minimum accumulation length and a second position of maximum accumulation length, respectively in a forward direction of increase in length and in a return direction of decrease, said strip passing over at least one return member (2) mounted on said carriage (1) to form at least two strands respectively go (B1) and return (B4) on at least two spaced apart levels, a plurality of intermediate support members (4) arranged along the track (3) and each comprising at least one separating arm (4) extending horizontally over at least one intermediate level between two levels of movement of the strip and mounted pivoting, about a vertical axis (80), on a fixed frame (A), and means (8) for controlling the pivot ot each arm (4) between an open position (M1) for the passage of the looping carriage (1) and a closed position (M2) for which the separating arm (4) extends transversely between the two levels of movement of the strip, said control means (8) being actuated, when the looping carriage (1) passes, by a follower device (6) cooperating with an active surface of a cam device (5) mounted on the looping carriage (1),
characterized in that the follower device (6) is offset with respect to the pivot axis (80) of the arm (4), in front of the latter in the forward direction of movement of the carriage (1) determining closure of the arm (4) and that the follower device (6) is connected to the means (8) for controlling the rotation of the arm (4) by a deformable articulated mechanism (7) having two extreme stable positions, respectively a first position (M3 ) corresponding to the open position (M1) of the arm (4) and a second position (M4) corresponding to the closed position (M2) of the arm, said articulated mechanism (7) being associated with means for detachably holding the mechanism with locking , at least in the second position (M4) for closing the separating arm (4), said removable holding means (74) being actuated only by the follower device (6) cooperating with the cam device (5) when the carriage passes loop (1), respectively for blocking the mechanis me in the forward direction of the carriage (1) and for release in the return direction. Accumulator according to claim 1, characterized in that, each separating arm (4) being fixed in rotation on a vertical shaft (82) mounted pivoting about a pivot axis (80), the means for control (8) of the rotation of the arm (4) comprise a first lever arm (81) fixed in rotation on the shaft (82), transversely to the pivot axis (80) and having one end connected by an articulated mechanism (7) to a second lever arm (62) pivotally mounted on the fixed frame (A) around a vertical axis (60) separated longitudinally the pivot axis (80) of the arm (4) in front of the latter and having one end on which a roller (61) is mounted constituting the tracking device cooperating with the cam device (5), the latter determining, by movement of the carriage (1), simultaneous rotation of the two lever arms (81, 62) connected by the articulated mechanism (7). Accumulator according to claim 2, characterized by the fact that the articulated link mechanism (7) comprises a third lever arm (72) integral in rotation of the second lever arm (62) about the axis (60) pivoting thereof and having one end connected by a connecting rod (73) at one end of the first lever arm (81), one or the other of the two lever arms (62, 72) integral in rotation, being connected by a return spring (74) at an attachment point (9) placed on the fixed frame (A) in a position diametrically opposite to a position center of the follower roller (61), on either side of which the second lever arm (72) is biased by the return spring (74) to either of two stable angular positions of the connecting mechanism (7) which determine, through the connecting rod (73) and the third lever arm (72), holding the arm (4), respectively in the open position (M1) or in the closed position (M2), as long as the roller (61) is not solicited, by the passage in one direction or the other of the active surface (51) of the cam device (5). Accumulator according to claim 3, characterized in that in the second stable position (M4) of the articulated mechanism (7), the connecting rod (73) is placed substantially in the extension of the third arm of lever (72), so that an untimely action on the arm separator (4) tending to pivot the latter with the first lever arm (81), determines a thrust on the connecting rod (73) directed substantially towards the axis (60) of the third lever arm (72) with self-locking effect of the articulated mechanism (7). Accumulator according to claim 4, characterized in that in the second stable position (M4) of the articulated mechanism (7), one or the other of the two lever arm (62, 72) integral in rotation is supported on a fixed stop (64) whose position is adjusted in such a way so that the connecting rod (73) and the third lever arm (72) determine the blocking of the mechanism (7) by knee pad. Accumulator according to one of claims previous, characterized in that each organ of support (4) comprises two parts respectively placed on either side of the passage (3) of the carriage loop (1) and each comprising a shaft (82, 82 ') mounted rotatable around a vertical axis (80, 80 ') and bearing at at least a half-arm (41, 41 '), each shaft (82, 82') being connected by an articulated mechanism (7, 7 ') to a device follower (6, 6 ') cooperating with a cam device (51, 52) for controlling the simultaneous pivoting of the two shafts (41, 41 ') between an open position for which the half-arms (41, 41 ') are spread apart parallel to the axis longitudinal, and a closed position for which both half-arms (41, 41 '), at each intermediate level, are substantially aligned in a direction perpendicular to the longitudinal axis. Accumulator according to one of claims previous, characterized by the fact that the loop (1) carries at least two deflection rollers (2) each defining two levels of scrolling, in some directions opposite, of the band.

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