EP0333596B1 - Device for stacking flat objects such as envelopes - Google Patents

Abstract

Device for forming a stack (18) of flat articles (20) on a support, comprising a means (24) for delivering the flat articles and stacking means (22) which comprise a belt (34) passing over two pulleys (36, 38) and which pivot about the axis of the pulley (38) located on the opposite side to the means (24) for delivering the flat articles. <IMAGE>

Description

The invention relates to a device for forming a stack of flat objects, such as for example letters, postal envelopes or the like, on a dihedral-shaped support with two perpendicular walls on which the flat objects are supported by a front edge and a side edge.

Such a device can be used in particular in postal sorting installations, for example to form a buffer stock of letters between two sorting machines.

Letters leaving a machine of this type are generally stored in boxes which are transported to the next machine. A stack of letters is placed by hand on a support in the form of a right dihedral at one end of which is provided an unstacking device which removes the letters one by one from the stack and places them at the entrance of means of transport supplying a other machine. For transport, the letters are generally pinched between two endless belts or bands guided on rollers along the path to be traveled, being arranged between the belts either in tiled formation (the front edge of a letter covering the rear edge from the previous letter), or separated from each other.

Also known, from German patent application 3,237,815, is a device for forming a stack of letters on a dihedral-shaped support, this device comprising means for transporting letters to the immediate vicinity of the support, means for stacking letters on the support, and means for relative displacement of the means of transport and means for stacking relative to the support or to the stack of letters formed on the support. In this known device, the means for stacking the letters on the support are pivotally mounted on the end of the means for transporting the letters, so as to be able to move away from the stack of letters and control their advance, for example when a relatively thick letter arrives.

Due to the mounting of the pivoting stacking means on the end of the transport means, which are themselves mounted fixed relative to the stack of letters, this known device does not very well accept particularly rigid or particularly letters thick. This malfunction is further accentuated by the fact that the letter stacking means are oriented slightly at an angle to the stack of letters and cause the upper letters of the stack to fold.

Finally, the inertia of the pivoting assembly comprising the letter stacking means is relatively large, which prohibits high rates of routing and stacking of the letters on the support.

Document US-A-4,084,809 describes, in a photocopier or the like, a device for stacking sheets bearing on a wall, the device comprising a belt passing over two rollers, one of which is movable and carried by a system of articulated arms with counterweights, the other of which is powered and is carried by a frame outside the stack of sheets, beyond the support wall of the sheets. In this known device, only the roller carried by the articulated arm system is movable by pivoting above the stack of sheets, and the lower part of the belt bearing on the stack of sheets is bent as soon as the thickness of the stack of sheets exceeds a certain value. This known device is therefore not suitable for stacking a large number of relatively thick or rigid objects such as postal envelopes.

Document EP-A-0 231 961 describes a device for stacking sheets on a fixed support, this device comprising means for transporting the sheets up to a mobile carriage from which they are ejected on the top of the stack and means for moving the mobile carriage to maintain it at the top of the stack as it forms.

This device is also not suitable for stacking a large number of relatively thick or rigid flat objects such as postal envelopes.

The subject of the invention is a device for forming a stack of flat objects such as letters or postal envelopes, which does not have the defects and drawbacks mentioned above.

More generally, it relates to a device for forming a stack of flat objects from means bringing these objects one after the other, in tiled formation or one after the other, and making it possible to form a stack of variable length with input and output of flat objects independent of each other and simultaneous or not.

It also relates to a device of this type which is capable of working at a very high rate.

The invention therefore provides a device for forming a stack of flat objects such as letters or mail folds on a dihedral-shaped support with two perpendicular walls on which the flat objects are supported by a front edge and a lateral edge, this device comprising means of transport for bringing the flat objects one after the other onto the support with a predetermined orientation close to that which they must occupy in the stack; means for stacking flat objects on the support by sliding each flat object on the preceding flat object of the stack and abutting on a jogging wall of the support; means for moving the stack in the opposite direction to the transport means and the stacking means; and return means urging the stacking means towards the stack, the device being characterized in that the stacking means are independent of the transport means and are pivotally mounted about an axis close to the jogging wall of the support, and in that the stacking means and a part of the means of transport, adjacent to the stacking means, are carried by a table which is movable in translation parallel to the direction of formation of the stack and which is mounted floating relative to this stack to move away from it. arrival of a flat object from a distance equal to the thickness of this flat object.

The inertia of the stacking means on arrival of a flat object is thus reduced, which makes it possible to improve their response time and to increase the rate of routing and stacking of the flat objects. In addition, when a rigid or relatively thick flat object arrives, the stacking means pivot to move away from the stack of flat objects on the side of the end of the transport means, which makes it possible to better accept thick or particularly rigid objects. In addition, the table carrying the stacking means and part of the transport means is mounted floating relative to the stack of flat objects to move away from the latter by a distance equal to the thickness of the flat object that is added to the stack.

According to another characteristic of the invention, the movement of said table is controlled by means for detecting the angular position of the stacking means.

In a first embodiment of the invention, the stacking means comprise an endless belt or band passing over two pulleys, one of which is driven by motor means, and the other of which is movable by pivoting around the axis of the first pulley mentioned.

In this case, it is the belt which, applied on a flat object brought by the means of transport, causes it to slide over the end of the stack, while simultaneously moving away from this end of the stack by a distance corresponding to the thickness of the flat object .

Advantageously, the part of the belt which is in contact with the end of the stack is parallel to the flat objects of this stack.

This avoids folding and possible deterioration of the flat objects brought to the end of the stack.

It is also expected that the motor means for driving the aforementioned pulley in rotation are controlled by means for detecting the arrival of a flat object, associated with time delay means, for the automatic starting and stopping of these motor means.

This avoids possible deterioration of the last flat object brought, when it passes a certain time before the arrival of the next flat object.

As a variant, the stacking means comprise a drive shaft carrying a first cylindrical sleeve mounted to rotate inside a second cylindrical sleeve in contact with the latter, the coefficient of friction of the first sleeve relative to the second sleeve being much lower to that of the second sleeve on a flat object mentioned above.

Thanks to this arrangement, there is an automatic stop of the means for driving flat objects in the stacking means, as soon as a flat object is brought into abutment on the jogging wall of the support on which the stack of objects is formed. dishes.

• la figure 1 illustre schématiquement la constitution d'une pile d'objets plats sur un support en forme de dièdre à deux parois perpendiculaires ;
• la figure 2 est une vue schématique de dessus d'un dispositif selon l'invention ;
• la figure 3 est une vue partielle à plus grande échelle d'une partie de ce dispositif ;
• la figure 4 est une vue partielle en coupe du support, représentant une plaque de guidage des objets plats ;
• la figure 5 représente schématiquement une autre partie de ce dispositif ;
• les figures 6, 7 et 8 sont des vues de dessus illustrant le fonctionnement de cette partie ;
• la figure 9 représente schématiquement une variante de réalisation des moyens d'empilage.

The invention will be better understood and other characteristics, details and advantages thereof will appear on reading the description which follows, given by way of example with reference to the appended drawings in which:

• Figure 1 schematically illustrates the constitution of a stack of flat objects on a dihedral-shaped support with two perpendicular walls;
• Figure 2 is a schematic top view of a device according to the invention;
• Figure 3 is a partial view on a larger scale of a part of this device;
• Figure 4 is a partial sectional view of the support, showing a guide plate for flat objects;
• FIG. 5 schematically represents a other part of this device;
• Figures 6, 7 and 8 are top views illustrating the operation of this part;
• FIG. 9 schematically represents an alternative embodiment of the stacking means.

We first refer to FIG. 1 to explain the principle of constitution of a stack of flat objects of variable length on a support 10 in the form of a dihedral with two perpendicular walls 12 and 14. To simplify the description, we will assume that the walls 12 and 14 of the support are respectively horizontal and vertical, but the support can also be inclined in one direction or the other.

At one end of the support is a device 16 for unstacking flat objects, one face of which is perpendicular to the two walls of the support and from which is formed a stack 18 of flat objects 20 which will be called letters in the rest of the description. The stacking means 22 are at the end of the stack 18 opposite the unstacking means 16 and are associated with means 24 for transporting the letters 20. These letters are therefore brought one by one by the means 24 at the height of the means stacking 22 and are stored one after the other on the support 10 to constitute the stack 18. More specifically, the letters 20 brought on the support 10 are supported on the horizontal wall 12 thereof by their edge lower side, and are brought to bear on the vertical wall 14 or jogging edge by their front vertical edge. At the other end of the stack, the means 16 take the letters 20 one by one to move them in the direction indicated by the arrow 26 and bring them to the entry of other means of transport, not shown.

In known manner, the support 10 can comprise means of transporting the stack 18 towards the unstacking means 16, as indicated by the arrow 28. The stacking means 22 as well as part of the transport means 24 are movable in translation parallel to the direction of formation of the stack, as indicated by the double arrow 30, their position being slaved to the position of the last letter of the stack and therefore being able to vary according to the thickness of each letter , the speed of movement of the stack towards the unstacking means 16, the rate of operation of these unstacking means, their running and their stopping. We will now refer to Figures 2 to 4, showing in detail a device according to the invention.

We find in these figures the support 10, the unstacking means 16, the stacking means 22 and the associated transport means 24. The stacking means 22 and part of the transport means 24 are carried by the same table or plate 32 movable in the direction indicated by the double arrow 30, being guided on columns by means of ball bushings for example, and moved in one direction and in the other by reversible motor means, for example electric. The stacking means 22 comprise, in this embodiment, an endless belt or band 34 passing over two pulleys 36, 38 mounted on the table 32 so that the strand of the belt 34 which extends between the pulleys on the side of the stack of letters is substantially perpendicular to the direction of formation of the stack of letters. The two pulleys 36, 38 are separated from each other by a distance which is at most the length of the smallest letter to be placed in the stack. The pulley 36 (fig. 3) is carried by an arm 40 pivotally mounted on the vertical axis of the pulley 38 located in the vicinity of the jogging edge 14 and which is driven by means of a belt 42 passing over a motor shaft 44, for example an output shaft of an electric motor.

The pivoting arm 40 is associated with a return spring 46 which constantly urges it towards the end of the stack of letters, and with a position detector 48.

On the movable table or plate 32 is also mounted a guide plate 50, arranged vertically and which extends from the outlet of the transport means 24 to the jogging edge 14. As shown in FIG. 4, the jogging edge 14 comprises parallel grooves 52, which extend parallel to the direction of formation of the stack of letters 18 and into which engage ribs 54 of the corresponding vertical edge of the guide plate 50. Thanks to this arrangement, it is avoided that the front edge of a letter 20 pushed on the jogging edge does not fold along the latter, that is to say between the table 32 and the edge 14.

The means of transport 24 used are conveyors with endless belts or belts. More precisely, as shown in FIG. 2, they comprise a first belt 56 guided on pulleys or rollers, and a second belt 58 also guided on pulleys or rollers, the two belts 56, 58 being parallel and applied one on the other over part of their length, which defines the path of the letters between the entry 60 of the means of transport and their exit 62.

The belt 56 passes over two pulleys 64 carried by a fixed frame and separated from each other by a distance greater than the length of the stack of letters which it is desired to form on the support 10. Other pulleys 66 also mounted on the frame define the start of the common path of the belts 56, 58.

The other pulleys 68 over which the first belt 56 passes are mounted on the movable table 32, two of these pulleys, designated by the reference 68a, forming the input and output pulleys of the belt 56 on the table 32 being arranged with so that the movements of the table 32 in the direction of the double arrow 30 do not cause any variation in length and tension of the belt 56. The two pulleys 68a are preferably aligned with each other parallel to the direction of the double arrow 30, as well as the end pulleys 64 mounted on the fixed frame.

The same rule is valid for the second belt 58 which also passes over end pulleys 70 spaced apart by a distance substantially equal to that which separates the pulleys 64. For reasons of space, this loop of the belt 58 is disposed in a vertical plane, under the table 32, the belt 58 passing for this purpose on return pulleys 72 of horizontal axis, one of which is mounted on the table 32 and the other on the fixed frame.

At the end of the common path of the two belts, which corresponds to the outlet of the transport means 24, the belt 56 passes over a pulley 68b relatively close to the first pulley 36 of the stacking means 22 while the belt 58 leaving the last pulley 68 of the common path, is guided via a small pulley, towards the return pulley 72 of the table 32. The distance between the last pulley 68 of the common path and the pulley 68b is less than the minimum length of a letter 20 and the orientation of the belt 56 between these two pulleys is such that each letter is brought to the support 10 with an orientation slightly inclined relative to that which it will occupy in the stack 18.

We see in FIG. 2, on the wall 12 of the support 10, two notched belts 74 which make it possible to advance the stack of letters towards the unstacking means 16.

The device works as follows:
The letters 20 are transported by the means 24, from the inlet 60 to the outlet 62 while being pinched between the belts 56 and 58 on their common path shown in FIG. 2, the transport rate being for example around 10 letters per second on average. Each letter 20 leaving the transport means 24 is projected in the direction indicated by the arrow in FIG. 2, towards the stacking means 22, more precisely between the latter and the last letter of the stack 18. The letter 20 leaving the transport means 24 is slightly oblique with respect to the arrangement of the letters in the stack, so that its front edge slides over the last letter, until it comes into contact with the belt 34 passing over the pulleys 36, 38. The arrival of the letter in this position is detected by appropriate means, for example by a photoelectric cell 84 which controls the starting of the motor drive means of the pulley 38. The rotation of this pulley results, by l through the belt 34, by the rotation of the pulley 36 and by the movement of the belt 34, along the last letter of the stack, in the direction of the jogging edge 14. The letter which has just left the means transport 24 and whose front edge is engaged between the pulley 36 and the last letter of the stack is thus brought in the direction of the jogging edge 14, until the front edge of this letter abuts on the edge 14 A timing circuit sation 86 automatically stops movement of the belt 34. The aforementioned plate 50 guides the letter 20 and prevents the front edge of the latter from folding back, between the bank 14 and the table 32 .

The passage of the last letter stacked in front of the pulley 36 necessarily resulted in a pivoting of the arm 40 around the axis of the pulley 38, the rearward movement of the pulley 36 corresponding substantially to the thickness of the letter being stacked. The movement of the arm 40 or of the pulley 36 is detected by the means 48, the output signal of which is transmitted to a control circuit controlling the movement of the table 32 in the direction opposite to the unstacking means 16. By other words, each time a letter takes its place in the stack 18, the table 32 and the stacking means 22 are moved back a distance equal to the thickness of this letter. Between two letter arrivals, the spring 46 keeps the pulley 36 and the belt 34 pressing on the last letter of the stack.

Similarly, if the stack advances, regularly or in spurts towards the unstacking means 16, the movement of the arm 40 urged by the spring 46 is detected by the means 48, and the control circuit controls the movement of the table 32 towards the unstacking means 16.

The device therefore makes it possible to form a stack of variable length on the support 10, from one end of this support which is defined by the face of the unstacking means 16 on which the stack 18 is supported, the maximum length of this stack corresponding for example to 1000 letters, or else having a predetermined value, of the order of 1 meter or more. When this maximum stack length is reached, for example following an operation stop of the unstacking means 16, the stop of the transport means 24 and possibly that of the machine located upstream are controlled.

To facilitate stacking, provision may be made for the means 22 to be housed in a box 88 provided with a suction means such as a fan and comprising a suction slot at the level of the belt 34. In this way, each letter 26 arriving between the stacking means 22 and the last letter of the stack is pressed against the belt 34 by suction effect, which makes it possible to move this letter more surely until it stops on the jogging edge, and this without increasing the pressure on the already formed pile.

It is also possible to use, at the outlet of the transport means 24, the means shown in FIGS. 5 to 8. This means 76 has substantially the shape of a U lying on its side, so that the belt 56 at the outlet of the transport means 24 passes between the two lateral branches of this U which is mounted fixed in position and which is relatively rigid.

As the height of the belt 56 and that of the means 76 are less than the minimum height of a letter to be transported, each letter 20 leaving the last pulley 68 of the transport means 24, and passing over the branches of the U 76 causes the belt 56 to flex inwards as shown in FIG. 7.

When the rear edge of the letter 20 exceeds the end of the branches of the means 76, the belt 56 again engages between these branches, pushing the rear edge of the letter 20 (Figure 8) which pivots slightly around its edge before. This prevents the front edge of the next letter from coming up against the rear edge of this letter.

There is shown in Figure 9, an alternative embodiment of the stacking head. In this variant, the pulley 36 is replaced by a drive shaft 78 surrounded by a sleeve 80 which is rotationally integral with the shaft 78 and which rotates inside another sleeve 82, while being in contact with that -this. The materials of these two sleeves are chosen so that the coefficient of friction of the sleeve 80 inside the sleeve 82 is much lower than the coefficient of friction of the sleeve 82 on a letter 20 conveyed by the means of transport. In this way, when the letter 20 leaving the transport means 24 engages between the sleeve 82 and the last letter of the stack, the rotation of the shaft 78 and of the sleeve 80 results in a rotation of the outer sleeve 82, which moves the letter 20 until its front edge comes to a stop on the jogging edge. From this moment, the friction of the sleeve 82 on the letter 20 results in the rotation stop of the sleeve 82, inside which the sleeve 80 driven by the shaft 78 continues to rotate.

The motor shaft 78 can therefore be driven continuously, and it is no longer necessary to use a photoelectric cell and a timing circuit to control its rotational movement.

In general, the device according to the invention can operate with means of transport bringing letters or flat objects, of different formats, one after the other, either separated from each other, or in tiled formation. On leaving the device, the unstacking means make it possible, depending on their type, to remove the flat objects one after the other, either separated from each other, or in tiled formation.

Although we have described in the above a fixed unstacking device in position on the support 10, it is obvious that this device could be movable in translation in one direction and in the other parallel to the direction of formation of the battery, and that this variant falls within the scope of the invention.

Claims (10)

1. Apparatus for forming a stack of flat objects such as letters or postal items on a support (10) in the form of a trough having two mutually perpendicular walls (12, 14) with each flat object (20) bearing thereagainst via its leading edge and via one of its side edges, said apparatus including conveyor means (24) for bringing flat objects (20) one after another to the support (10) at a predetermined orientation, close to the orientation the flat objects are to occupy in the stack (18); stacking means (22) for stacking the flat objects on the support (10) by sliding each flat object over the preceding flat object on the stack and moving it into abutment against a jogging wall (14) of the support (10); means for displacing the stack (18) away from the conveyor means (24) and the stacking means (22); and return means (46) urging the stacking means (22) towards the stack (18), the apparatus being characterized in that the stacking means (22) are independent of the conveyor means (24) and are pivotally mounted about an axis close to the jogging wall (14) of the support (10), and in that the stacking means (22) and a portion of the conveyor means (24) close to the stacking means (22) are carried by a table (32) which is movable in translation parallel to the direction in which the stack (18) is built up and which is loosely mounted relative to the stack so as to move away therefrom on the arrival of a flat object through a distance equal to the thickness of said flat object.
2. Apparatus according to claim 1, characterized in that the displacement of said table (32) is controlled by means (48) for detecting the angular position of the stacking means (22).
3. Apparatus according to claim 1 or 2, characterized in that the stacking means (22) comprise an endless band or belt (34) passing over two pulleys (36, 38) one of which (38) is driven by drive means (42, 44) and the other of which (36) is displaceable by pivoting about the axis of the first-mentioned pulley (38).
4. Apparatus according to claim 3, characterized in that the portion of the belt (34) in contact with the end of the stack (18) is parallel to the flat objects in the stack.
5. Apparatus according to claim 3 or 4, characterized in that the drive means (42, 44) for rotating the pulley (38) are controlled by means (84) for detecting the arrival of a flat object, in association with timing means (86) for automatically starting and stopping said drive means.
6. Apparatus according to claim 1 or 2, characterized in that the stacking means include a drive shaft (78) carrying a first cylindrical sleeve (80) mounted to rotate inside a second cylindrical sleeve (82) and in contact therewith, with the coefficient of friction between the first sleeve (80) and the second sleeve (82) being very much less than the coefficient of friction between the second sleeve (82) and any one of the above-mentioned flat objects.
7. Apparatus according to any preceding claim, characterized in that the conveyor means (24) comprise two endless bands or belts (56, 58) passing over pulleys, with the flat objects (20) being pinched between said endless bands or belts which run parallel to each other and which press against each other over a portion of their lengths.
8. Apparatus according to any preceding claim, characterized in that the stacking means include a guide plate (50) for guiding the flat objects (20) said plate (50) being carried by the above-mentioned moving table (32) and extending from the outlet of the conveyor means (24) to the jogging wall (14) of the support, the leading edge of the guide plate (50) including projections or teeth (54) engaged in grooves (52) in the jogging wall (14), said grooves running parallel to the direction in which the stack (18) is formed.
9. Apparatus according to any preceding claim, characterized in that the stacking means (22) are received in a housing (88) containing air suction means for putting the inside of the housing at a reduced pressure such that each flat object is sucked onto the drive means (34).
10. Apparatus according to any preceding claim, characterized in that it includes pivot means (76) at the exit from the conveyor means (24), the pivot means (76) pivoting the flat objects (20) about their leading edges and serving to disengage the exit from the conveyor means, with the pivot means (76) comprising a fixed member having two branches between which one of the belts (56) of the conveyor means (24) passes.

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