EP0480810A1 - Depilinghead for flat objects, in particular for objects like letters or envelopes - Google Patents

Abstract

Destacking head for extracting, one by one, from a stack, especially a horizontal stack, vertically-disposed flat articles (2), comprising a pivoting arm (18) fitted with a movable and perforated conveyor belt (7) which is guided and stretched between two rollers (9, 10) having parallel and vertical axes (11, 12) which can occupy, respectively, two positions where, in the first position, the conveyor belt of the arm is in contact with the first article of the stack and extends substantially parallel to the conveyor belt and, in the other position, the arm is disengaged from the stack. According to the invention, this head is characterised in that the pivoting arm comprises, mounted inside the conveyor belt between the rollers, a parallelepipedal cage (21) which is open on that one of its vertical faces directed towards the first article of the stack in contact with the movable conveyor belt, this cage being connected at its top and bottom extremities (22, 23), which are free of ends (bottoms), via a connecting conduit (27) to a suction tubing (34), suitable for creating in the cage and through the perforated conveyor belt a partial vacuum attracting the first article thus held up against the conveyor belt and entrained with the latter.

Description

The present invention relates to a unstacking head one by one of flat objects, in particular of the kind of letters or mail envelopes, parallel to each other and arranged in a stack fed continuously or discontinuously by its end opposite the head of unstacking, the flat objects, which have variable formats and thicknesses, having to be able to be moved in a safe and regular manner by the head until an opposition where it delivers them to a conveyor belt or the like, capable of conveying them towards a indexing station or other processing, in a mail sorting facility.

Sorting installations are already known, comprising at least one unstacking head, this comprising a perforated belt, driven in rotation on two rollers or pulleys ensuring its guidance and its tension, this belt delimiting with edge plates connecting the axes parallel to the rollers, a substantially enclosed space in which a depression can be created such that it causes the first envelope of the stack to be sucked against the belt, then its displacement with the latter up to the end of the head from where it escapes to be taken up by a conveyor or a similar transfer mechanism, allowing it to be distributed to the rest of the installation. Generally, the head is carried by a pivoting support, arranged so as to apply it permanently on the pile with an adjustable pressure which depends on the flow with which the letters feed the pile in formation.

However, if these conventional heads are well suited when the letters of the stack have substantially the same format, it is different with heterogeneous flat objects, the characteristics of which vary from one to the other according to their three dimensions (length, width, thickness), in their mass or texture, in paper, strip, plastic ...

The present invention relates to a special unstacking head which avoids these drawbacks, by allowing flat objects of this kind to be treated, notwithstanding the variations in shape or presentation which they comprise from one to the other, this head further ensuring a significant increase in the rate of unstacking of the objects and as a result of their transfer into the installation.

To this end, the head considered, for the unstacking one by one of a stack, in particular horizontal, of flat objects arranged vertically, comprising a pivoting arm provided with a movable and perforated belt, guided and stretched between two rollers with parallel axes and vertical, being able to occupy respectively two positions where, in one the arm strap is in contact with the first object of the stack extending substantially parallel to the strap and, in the other, the arm is released from the stack, is characterized in that the pivoting arm comprises, mounted inside the belt between the rollers, a parallelepiped cage, open on one of its vertical faces directed towards the first object of the stack in contact with the moving belt, this cage being connected at its upper and lower ends deprived of funds by a connection conduit with a suction pipe, suitable for creating in the cage and through the perforated belt, a depression a pulling the first object, thus pressed against the belt and driven with it.

In a particular embodiment of the invention, and in a manner known per se, the pivoting arm comprises two horizontal edges, supporting the vertical axes of the rollers of the moving belt and delimiting with this belt a substantially closed space, the edges comprising perforations in line with the ends of the cage. The two strands extend laterally and are joined by a vertical pivot carried by a fixed support around which the arm moves when the latter passes from one to the other of its two positions.

Preferably, the connection conduit of the cage and the suction tubing has a C shape and is joined in its central part to the tubing by means of a connection flange on which a bellows fits, suitable for compensate for the variations in length created by the pivoting of the arm between its two positions, the bellows making it possible to return the arm to its released position due to the depression created in the connecting duct following contact with the perforated belt with the first object of the battery.

According to a particular characteristic of the unstacking head considered, the suction pipe comprises an exhaust socket, mounted for rotation on the pipe and suitable for opening or closing orifices or slots provided in the latter, so that, depending on whether the bushing is in the open or closed position of these orifices, the vacuum created in the cage, inside the belt, is minimum or maximum.

Advantageously, the rotation of the exhaust sleeve relative to the tubing for controlling the opening or closing of the orifices of the suction tubing is carried out by means of a pneumatic or electromagnetic cylinder, the movable rod of which is articulated on a lever secured to the socket, so as to cause the latter to travel, following the actuation of the jack.

According to another advantageous characteristic, the suction pipe also comprises a shut-off valve, normally open and the closing of which is automatically controlled upon contact of the perforated belt with the first object of the stack, due to the brutal suction created when applying the strap on this object, establishing the nominal suction pressure in the tubing.

Thanks to these arrangements, the closure valve remains in the open position, as long as the pivoting arm does not come into contact with the first object of the stack, in particular when it is in the released position vis-à-vis screw of it. On the other hand, as soon as the perforated belt comes into contact with this object when the pivoting arm is moved towards the stack, the valve is violently sucked in by the air flow created in the tubing as soon as the exhaust sleeve is closed, in achieving the maximum suction pressure inside the cage. The suction valve thus makes it possible to ensure that the vacuum inside the suction pipe is as low as possible during the pivoting of the arm, in particular in its movement towards the stack, so as to avoid that the vacuum created compresses the bellows before the belt is in contact with the first object, exerting a force opposing the direction of movement of the arm.

According to yet another characteristic, at least one of the edges of the arm is subjected to the action of the movable rod of a second cylinder, pneumatic or electromagnetic, with pulse control, causing the displacement of the pivoting arm from its released position from the pile to its position where the perforated belt is in contact with the praying object, the jack ensuring the damping of the arm when the latter returns to its released position.

Preferably, the pivoting arm is held in the position separated from the stack by means of a hard point mechanism, in particular consisting of a ball applied against one of the edges of the arm and subjected to the action of a spring authorizing the erasure of the ball, during an impulse created by the jack.

The movement of the arm, thus launched at each impulse of the jack, takes place simultaneously with the placing in the closed position of the exhaust bushing. When the cylinder reaches the end of its travel, which corresponds to about half the amplitude of the arm, it continues to move towards the stack until the belt comes into contact with the first object, ensuring instantaneous closing of the valve. The depression then created, at the same time as it takes hold of this object, determines the compression of the bellows and consequently the recoil of the arm with the latter, bringing it back to its released position.

The speed of the arm is damped during its return movement to its initial position where it is released from the stack, thanks to the presence of the jack. In fact, at the moment when the latter is in contact with the arm and propels the latter towards the stack, the chambers of the jacks are at atmospheric pressure or, as the case may be, at a minimum pressure. The jack can thus serve as a shock absorber thanks to the provision of a calibrated leak at the exhaust of its control fluid, thus avoiding a violent shock, when the arm arrives in the released position of the stack.

The restoring force of the arm is also proportional to the section of the bellows and to the difference between the atmospheric pressure and the vacuum created inside the tubing, thus making it possible to obtain a reaction time and restoring of the arm very low.

According to yet another characteristic, one of the guide rollers of the perforated belt is a driving roller, so as to control the drive of the belt once the pivoting arm in the released position of the stack, in order to move the object applied by the vacuum against the belt. Advantageously, said object is delivered by the belt on a discharge conveyor to an appropriate sorting installation.

• La Figure 1 est une vue en perspective de la tête de dépilage considérée, représentée avec l'ensemble de ses parties convenablement assemblées.
• La Figure 2 est une vue à plus grande échelle, en perspective éclatée, illustrant avec plus de détails les diverses parties de la tête.
• La Figure 3 est une vue en coupe partielle, à encore plus grande échelle, de la tête considérée, notamment au droit de la cage réalisant l'aspiration des objets de la pile.

Other characteristics of an unstacking head established in accordance with the invention will become more apparent from the following description of an exemplary embodiment, given by way of non-limiting example, with reference to the appended drawings in which:

• Figure 1 is a perspective view of the unstacking head considered, shown with all of its parts suitably assemblies.
• Figure 2 is an enlarged view, in exploded perspective, illustrating in more detail the various parts of the head.
• Figure 3 is a partial sectional view, on an even larger scale, of the head considered, in particular to the right of the cage carrying out the suction of the objects from the stack.

The unstacking head shown as a whole in FIG. 1, is designated under the reference 1, this head being in particular intended to ensure the gripping and the release one by one of flat objects 2, of the kind in particular of letters or more generally d 'mail envelopes with a possibly variable structure from one envelope to the next, as regards its dimensions, its thickness, its weight or its texture.

The objects 2 are contained inside a magazine 3 in which they are arranged in a stack, preferably so as to rest by their lower edge against a support or horizontal table on which the unstacking head 1 is also mounted. particular structure of the magazine 3 and in particular the means which they comprise for ensuring the supply of the battery by its end opposite to the head with other envelopes in the direction of the arrow 5, as and when these envelopes are one by one removed from the stack, are indifferent to the present invention. Advantageously, the store 3 for dynamic storage of the stack could be produced in accordance with the arrangements described and claimed in another patent application filed today in the name of the same inventors for a "device for dispensing flat objects". In the example shown, the magazine 3 can also be associated with a retractable lock 6, holding the stack inside the magazine, this lock being released each time the unstacking head comes to grip the first object in the stack, then returning to the initial position until the head, after having moved and delivered this first object in the manner described below, returns against the stack to grasp the next object in it and so on.

Figures 1 and 2 make it possible, respectively in the assembled position and in exploded perspective, to define all of the components involved in the production of the head 1.

As can be seen in these drawings, the head mainly comprises a belt 7, closed on itself and comprising in its surface a set of perforations 8, distributed throughout the belt. The latter is intended to be guided and tensioned, respectively between two rollers 9 and 10 whose axes 11 and 12 are arranged vertically. These axes protrude slightly on either side of the rollers so as to engage in holes such as 13, forming bearings, formed in two horizontal edge plates, respectively 14 and 15, extending on either side. of the perforated belt 7 ensuring the support of the rollers 9 and 10, while allowing their free rotation and the drive of the belt. These edge plates 14 and 15 extend laterally beyond the belt 7 and are joined to each other by means of a pivot 16, carried by a fixed frame 17 mounted on the support 4, so that the assembly constituted by the two edge plates and the belt form an arm 18 articulated around the pivot and capable of moving by turning on the latter between two positions, one corresponding to that where this arm is in contact with the first object 2 in the stack in order to come and grab it and extract it, and the other to the one where the arm is angularly released in order to release the grabbed object, in particular to deliver it to a conveyor Evacuation 19.

The two edge plates 14 and 15 delimit with the perforated belt 7 an internal space in the latter, substantially closed and in which is mounted a cage 21 of generally parallelepiped shape. The cage 21 is open at its upper 22 and lower 23 ends respectively, and has in its face 24 directed towards the stack of objects 2, in particular in contact with the belt 7, openings 25 (See also Figure 3), allowing the outside air to penetrate into the internal region 26 of the cage 21 by passing through the perforations 8 of the belt 7 and its openings, when an appropriate depression is established in the internal region 26 of the cage allow the first object 2 captured in the stack to be pressed against the belt when the arm 18 is brought into contact with the latter.

The open ends 22 and 23 of the cage 21 are joined to a connecting conduit 27 through openings 28 and 29 arranged opposite in the edge plates 14 and 15. This conduit 27 advantageously takes the form of a C and has in its central part a flange 30, making it possible to connect the conduit with one of the ends 31 of a bellows 32 whose opposite end 33 is joined to a suction pipe 34. This in turn is connected to a turbine or other means for sucking in the air contained inside the tubing and consequently, through the bellows 32 and the connecting piece 27, in the region 26.

The suction pipe 34 comprises a series of orifices or slots 35, regularly distributed around its periphery and capable of being, depending on the case, open or closed by means of an exhaust sleeve 36, surrounding the pipe in the region of these slots, this socket being itself provided with homologous slots 37, capable of coming to coincide with those of the tubing, according to the relative position of the socket. This comprises an external lever 38, the end 39 of which can be mounted and articulated in a yoke 40, provided at the end of the movable rod 41 of a pneumatic or electromagnetic cylinder 42, so that the control of this cylinder determines at will an alternating movement of the lever 38 and consequently, the relative rotation of the sleeve 36, opening or closing the slots of the tubing 34.

The latter also comprises a shut-off valve 43, the axis 44 of which is axially movable in the pipe, this valve cooperating with a seat 45 formed in the wall of the latter, to make it watertight when the valve is applied to this seat.

The equipment of the unstacking head is completed by means of a second pneumatic or electromagnetic cylinder 46, the rod 47 of which comprises at its opposite end a stopper 48, capable of coming to bear against one of the edge plates, here the plate 15, this cylinder, controlled by pulses, making it possible to produce a limited lateral thrust on the arm, nevertheless sufficient to cause it to move from its position released from the stack, in the direction of the latter by bringing the perforated belt 7 into contact with the first object 2 in the stack. The cylinder 46 is advantageously associated with a hard point mechanism 49, constituted by a support cup 50 for a ball 51, normally pressed against the edge plate 15, this ball being subjected to the action of a spring (not shown ), allowing it to disappear during the impulse created by the push of the stopper 48, causing the arm 18 to pivot.

Finally, in FIGS. 1 and 2, a particular embodiment of the discharge conveyor 19 has been schematized, comprising a horizontal sole belt 52 and two edge belts 53 and 54 between which the object 2 extracts from the stack and delivered by the pivoting arm 18, is suitably maintained and driven towards the rest of the installation. Similarly, the means for controlling the drive of the perforated belt 7, one of the guide rollers thereof, have been illustrated, here the roller 9 having its axis 11 secured to a pulley 55, itself driven by a return belt 56, from a drive pulley 57, itself controlled through the axis of the pivot 16 by means of a motor 58.

The operation of the unstacking head described above is deduced from the foregoing explanations. The magazine 3 being loaded by means of a stack of objects 2 and the evacuation conveyor 19 being driven in continuous movement, the tube 34 is connected to its turbine which creates the necessary suction pressure. The pivoting arm 18 is initially in the released position of the stack, the distance which separates it from the latter being determined by construction and in principle always identical to itself. Note, however, that a slight variation around this position is not a problem, the head being arranged to automatically make up for the corresponding gap.

In this initial phase, the shut-off valve 43 is open, as is the exhaust socket 36 putting the tubing 34 and the external atmosphere into communication through the slots 35 and 36.

When the cycle starts, the jacks 42 and 46 are simultaneously controlled so that, on the one hand, a movement impulse is transmitted to the edge plate 15 of the arm by means of the stopper 48, exceeding the resistance of the hard point mechanism 49 and causing the arm to be launched from its initial position released from the stack to its opposite position where the perforated belt 7 is in contact with the first object 2, on the other hand, the limited rotation of the sleeve is controlled 36, closing the exhaust slots.

During this movement of the arm, the shut-off valve 43 remains open, making it possible to maintain the vacuum inside the connection conduit 27 and the cage 21 at a minimum value, avoiding the compression of the bellows 32 which would otherwise exert a restoring force on the arm, contrary to the desired displacement.

When the belt 7 comes into contact with the first object 2 at the end of the arm travel, the perforations 8 of the latter are suddenly closed, causing in the tubing 34 a brutal aspiration of the air flow and an immediate closure of the valve 43 The depression inside the cage 21 in the region 26 thereof increases accordingly and tightly presses the first object 2 against the belt. Simultaneously, the vacuum is created, compresses the bellows 32 which then exerts on the pivoting arm 18 an effort sufficient to allow it to be returned to its original released position.

In the latter, the drive of the perforated belt 7 is then controlled, via the roller 9, the belt 56 and the pulleys 55 and 57 by means of the motor 58, so that the object 2 pressed against the belt is delivered to the conveyor 19, which it discharges through its sole belt 52, between the belts 53 and 54. At the same time, the jack 42 is controlled in the direction which causes the slots 35 and 37 to open through socket 36, with opening automatic and concomitant of the valve 43, the arm being ready to undertake a new cycle, to go and apprehend the next object in the stack and so on. In particular, the arm can start a new cycle as soon as the previous object has left the head, which means that the latter is able to deliver these objects with a constant deviation, very reduced. Furthermore, it is also possible to unstack the objects with a constant pitch, the flow obtained being in this case less important.

A unstacking head of simple design is thus produced which allows the gripping of various objects which are not necessarily identical from one to the other, in particular envelopes of postal couriers to be processed in an automated sorting installation. The pivoting arm makes it possible to obtain high rates, the rate of the objects being able to be much higher than three per second, the reaction time of the head being particularly limited. The operation of the assembly is safe, the suction effect provided by the vacuum inside the perforated belt being created for the time just necessary. In addition, this effect is directly used to cause the recoil movement of the arm, without requiring any other suitable mechanism. Finally, the provisions provided make it possible to rotate the object to be extracted from the stack with respect to a fixed pivot axis with the arm, which creates a non-zero speed gradient on the surface of the object improving their separation by dininuting the suction cup effect encountered when this separation is carried out, as in conventional installations, with a movement of movement in uniform translation.

Of course, it goes without saying that the invention is not limited to the embodiment more specifically described and shown above; on the contrary, it embraces all its variants.

Claims (12)

1 - Unstacking head, for the one-by-one extraction of a stack, in particular a horizontal stack, of flat objects (2) arranged vertically, comprising a pivoting arm (18) provided with a movable and perforated belt (7), guided and stretched between two rollers (9,10) with parallel and vertical axes (11,12) which can respectively occupy two positions where, in one the arm strap is in contact with the first object of the stack extending substantially parallel to the belt and in the other the arm is released from the stack, characterized in that the pivoting arm comprises, mounted inside the belt between the rollers, a parallelepiped cage (21), open on one of its vertical faces directed towards the first object of the stack in contact with the walking belt, this cage being connected at its upper and lower ends (22,23) deprived of funds by a connecting duct (27) with a suction pipe (34), suitable for creating in the cage and through the c perforated belt, a depression attracting the first object, thus pressed against the belt and driven with it. 2 - unstacking head according to claim 1, characterized in that the pivoting arm (18) comprises two horizontal edges (14,15), supporting the vertical axes (11,12) of the rollers (9,10) of the moving belt ( 7) and delimiting with this belt a substantially closed space, the edges comprising perforations (28, 29) in line with the ends of the cage (21). 3 - unstacking head according to claim 2, characterized in that the two banks (14,15) extend laterally and are joined by a vertical pivot (16) carried by a fixed frame around which the arm (18) moves when it passes from one to the other of its two positions. 4 - unstacking head according to any one of claims 1 to 3, characterized in that the connecting duct (27) of the cage (21) and the suction pipe (34) has a C shape and is joined in its central part to the tubing by means of a flange of connection (30) on which a bellows (32) adapts, capable of compensating for the variations in length created by the pivoting of the arm (18) between its two positions, the bellows making it possible to return the arm to its released position due to the depression created in the connecting duct (27) consecutive to the contact of the perforated belt (7) with the first object of the stack. 5 - unstacking head according to any one of claims 1 to 4, characterized in that the suction pipe (34) comprises an exhaust sleeve (36), rotatably mounted on the pipe and suitable for opening or closing orifices or slots (35) provided therein, so that, depending on whether the bushing is in the open or closed position of these orifices, the depression created in the cage (21) inside the belt (7) is minimum or maximum. 6 - unstacking head according to claim 5, characterized in that the rotation of the exhaust sleeve (36) relative to the tubing, for controlling the opening or closing of the orifices of the suction tubing, is produced by means of a pneumatic or electromagnetic cylinder (42), the movable rod (41) of which is articulated on a lever (38) integral with the sleeve, so as to cause the latter to travel, following the control of the cylinder. 7 - unstacking head according to any one of claims 1 to 6, characterized in that the suction pipe (34) also comprises a shut-off valve (43), normally open and the closing of which is automatically controlled during the contact of the perforated belt (7) with the first object of the stack, due to the brutal suction created during the application of the belt on this object, by establishing in the tubing the nominal suction pressure. 8 - unstacking head according to claim 7, characterized in that the shutter valve (43) remains in the open position, as long as the pivoting arm (18) does not come into contact with the first object (2) of the battery, in particular when it is in the disengaged position with respect to the latter. 9 - unstacking head according to any one of claims 1 to 8, characterized in that at least one of the edges (15) of the arm (18) is subjected to the action of the movable rod (47) of a second pneumatic or electromagnetic cylinder (46), controlled by pulses, causing the pivoting arm to move from its position released from the stack to its position where the perforated belt (7) is in contact with the first object (2), the cylinder ensuring the damping of the arm when the latter returns to its released position. 10 - unstacking head according to claim 9, characterized in that the pivoting arm (18) is held in the position away from the stack by means of a hard point mechanism (49), in particular consisting of a ball (51) applied against one of the edges of the arm (15) and subjected to the action of a spring authorizing the erasure of the ball during an impulse created by the jack (46). 11 - unstacking head according to any one of claims 1 to 10, characterized in that one of the guide rollers (9) of the perforated belt (7) is a motor roller, so as to control the drive of the belt once the pivoting arm in the released position of the stack, in order to move the object applied by the vacuum against the belt. 12 - unstacking head according to claim 11, characterized in that the flat object (2) is delivered by the perforated belt (7) on a discharge conveyor (19) to a sorting installation or the like.

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