EP0333596A1 - 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 belts or endless 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, this known device does not very well accept particularly rigid or particularly thick letters. 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 of stacking letters on the support.

The invention relates to a device of this type, not having 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, 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 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 transport means 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; the means for stacking flat objects on the support, by sliding each flat object on the previous flat object of the stack and abutting on a jogging wall of the support; and means for relative displacement of the transport means and stacking means with respect to the stack and / or the support, the stacking means being mounted so floating with respect to the stack, characterized in that the means of stack are movable towards and opposite the end of the pile, by pivoting around an axis close to the jogging wall of the support and are associated with return means urging them constantly towards the pile.

In this way, the inertia of the stacking means is 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 large flat object arrives, the stacking means move away from the stack of letters, on the side of the end of the means of transport, which makes it possible to better accept the objects. thick, as well as particularly rigid objects.

According to one 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 to a flat object brought by the means of transport, drives it by sliding on the end of the pile, while simultaneously moving away from this end of the pile of 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;
• - Figure 5 shows schematically a other part of this device;
• - Figures 6, 7 and 8 are top views illustrating the operation of this part;
• - Figure 9 schematically shows 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, towards 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 timer circuit 86 allows d 'automatically stopping the movement of the belt 34. The aforementioned plate 50 forms a guide for the letter 20 and prevents the front edge of the latter from folding backwards, between the edge 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 thickening 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 (11)

1) Device for forming a stack of flat objects such as letters on a support (10) in the form of a dihedral with two perpendicular walls (12,14) on which the flat objects (20) are supported by an edge front and a side edge, this device comprising transport means (24) for bringing the flat objects (20) one after the other onto the support (10) with a predetermined orientation, close to that which they must occupy in the stack (18); means (22) for stacking flat objects on the support (10) by sliding each flat object on the preceding flat object of the stack and abutting on a jogging wall (14) of the support (10); and means for relative displacement of the transport means (24) and stacking means (22) relative to the stack (18) and to the support (10), the stacking means (22) being mounted floating relative to to the stack (18), characterized in that the stacking means (22) are mounted movable towards and opposite the end of the stack (18) by pivoting about an axis close to the wall of jogging (14) of the support (10), and are associated with return means (46) urging them constantly towards the stack (18). 2) Device according to claim 1, characterized in that the stacking means (22) comprise an endless belt or strip (34) passing over two pulleys (36, 38) one of which (38) is driven by motor means (42,44) and the other (36) of which can be moved by pivoting about the axis of the first cited pulley (38). 3) Device according to claim 2, characterized in that the part of the belt (34) in contact with the end of the stack (18) is parallel to the flat objects of the stack. 4) Device according to one of claims 1 to 3, characterized in that the displacement means rela The means of transport and stacking with respect to the stack (18) and the support (10) are controlled by means (48) for detecting the angular position of the stacking means (22). 5) Device according to one of claims 2 to 4, characterized in that the motor means (42,44) for driving the pulley in rotation (38) are controlled by means (84) of arrival detection of 'a letter, associated with timing means (86), for the starting and automatic stopping of these motor means. 6) Device according to claim 1, characterized in that the stacking means comprise a drive shaft (78) carrying a first cylindrical sleeve (80) mounted to rotate inside a second cylindrical sleeve (82) in contact with the latter, the coefficient of friction of the first sleeve (80) relative to the second sleeve (82) being much lower than that of the second sleeve (82) on a said flat object. 7) Device according to one of the preceding claims, characterized in that the stacking means (22) and part of the transport means (24) are mounted on the same plate or table (32) movable in translation parallel to the direction of formation of the stack on the support, the other part of the transport means (24) being mounted on a fixed frame. 8) Device according to one of the preceding claims, characterized in that the transport means (24) comprise two endless belts or bands (56,58) passing over pulleys, the flat objects (20) being pinched between these belts or endless bands which are parallel and applied one on the other over a part of their length, and in that the pulleys (68) of the transport means (24) mounted on the plate or mobile table (32) stacking means are arranged with respect to the fixed frame so that the movement of the plate or movable table does not cause any variation in the length and the tension of endless belts or belts (56,58). 9) Device according to one of the preceding claims, characterized in that the stacking means comprise a plate (50) for guiding flat objects (20) extending from the outlet of the transport means (24) to the jogging wall (14) of the support, the corresponding front edge of the guide plate (50) comprising teeth or projections (54) engaged in grooves (52) of the jogging wall (14), these grooves being formed parallel to the direction of formation of the stack (18). 10) Device according to one of the preceding claims, characterized in that the stacking means (22) are housed in a box (88) containing air suction means putting the inside of the box under vacuum, such that each flat object is drawn by suction onto drive means (34). 11) Device according to one of the preceding claims, characterized in that it comprises, at the outlet of the transport means (24), means (76) for pivoting the flat objects (20) around their front edge, allowing to clear the outlet of the means of transport, these means (76) comprising a fixed member with two branches between which passes a belt (56) of the means of transport (24).

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