EP0634957B1 - Mail sequencing process for mail sorting systems - Google Patents

Abstract

In the method of the invention for sequencing parcels in mail-sorting facilities having rows of stacking compartments, a sorting plan is used for sorting the parcels in which an overfilling of the individual stacking compartments is avoided so that, during one sorting procedure, the stacking compartments are not emptied, and that, after a sorting procedure has ended, an in-sequence transfer of the parcels is effected from the stacking compartments into a conveying device disposed opposite the stacking compartments or into containers.

Description

The invention relates to a method for improved sequencing of mail in mail distribution systems.

In letter sorting systems, mail, in particular letters, is sorted according to a possibly preceding pre-sorting process and stored in a large number of stacking compartments. For each sorting cycle, the fineness of distribution that can be achieved is determined by the number of stacking compartments to which the mail is distributed. Often, however, it is neither desirable nor possible for practical reasons to provide a separate sorting bin for each smallest class of a sorting process. For example, if the mail is to be sorted according to the order of distribution in the mail carrier aisle, a separate sorting compartment will not be required for each mail recipient. Rather, the mail is distributed to a certain number of stacking compartments in the same sequence in which it is later distributed by the deliverer during his distribution route. The mail item is arranged in each sorting compartment in accordance with the prescribed sequence, so that with an appropriate arrangement of the stacking compartments, the entire mail item is arranged in accordance with the predetermined sequence. In order to be able to make do with a relatively small number of stacking compartments in sorting systems, e.g. in the Proceedings USPS Advanced Technology Conference, Washington, DC, December 2, 1992, p. 1061-1074 is described, the mail several times and possibly sorted indirectly.

US-A-5097959 describes a method for sorting mail items in the order of aisles in multiple sorting runs in letter distribution systems with rows of stacking compartments, in which the stacking compartments are not emptied during a sorting run, and in each case after the sorting run a reloading of the mail items from the mail items according to the order Stacking compartments takes place in a conveyor arranged opposite the stacking compartments.

Letter sorting systems are also already known, in which the stacking compartments are arranged opposite the substance input, so that after each sorting cycle, which is followed by a further sorting cycle, the mail item is quickly manually returned from the stacking compartments an input module can be entered. During the manual reloading process, the mail is handily transferred from the compartment to containers that are set up in a mobile frame opposite the stacking compartments. It is common for the containers to have a larger capacity than the stacking compartments, which are emptied several times during each sorting cycle for reloading. A precondition for sequencing according to the procedure described above is that the order of the consignments after the first and for all subsequent sorting processes and during re-entry is strictly observed (sequence integrity), for which it is necessary that the containers are in the correct order after each sorting process mobile frame or additional means of transport for material input, or sorted into groups suitable for further processing after the last sorting process. Disadvantages of the prior art are in particular that at least two surgeons are required for substance input and draining and that the re-stacking or intermediate stacking of the postal matter in containers increases the space requirement and the risk of violating the sequence integrity, since the stack in the container can easily fall over If the container is only partially filled and the sequence produced could be disrupted, the stacks are accidentally loaded into the wrong container, or the order of the containers is mixed up.

The object of the present invention is to provide a method which avoids the stated disadvantages of the prior art and enables simple, quick and safe sequencing of the mail item while maintaining the sequence integrity. Compared to the prior art, the method according to the invention has the advantage that only one operator is required, that practically no partially filled containers are created, that the risk of a violation of the sequence integrity is reduced and that less space is required.

The object is achieved according to claim 1. Further advantageous developments of the invention are contained in the subclaims.

The invention is based on the idea of not emptying the stacking compartments in a sequencing process during the sorting process, using a sorting plan in which, if possible, no stacking compartment overflows or overflows, and if a stacking compartment is full, an overflow compartment is assigned to it , into which further stacking takes place, and after the end of the sorting process, the contents of the stacking compartments are transferred in sequence directly into a conveyor device operating the input module or into containers and fed to the input module or other further processing in accordance with the sequence.

Fig. 1

zeigt eine Briefsortieranlage zur Ausführung des erfindungsgemäßen Verfahrens,

Fig. 2

illustriert die Zuordnung des Inhalts eines Behälters zu den einzelnen Stapelfächern nach dem Entladen der Fächer für den Fall, daß jedem Bestimmungsort (Richtung) zwei Fächer vergeben werden,

Fig. 3

zeigt die Reihenfolge der sequentierten Sendungen in den Stapelfächern bei 800 Stops,

Fig. 4

zeigt die Reihenfolge der sequentierten Sendungen in den Behältern bei 800 Stops.

The invention is explained in more detail below with reference to drawings.

Fig. 1

shows a letter sorting system for performing the method according to the invention,

Fig. 2

illustrates the assignment of the contents of a container to the individual stacking compartments after the compartments have been unloaded in the event that two compartments are assigned to each destination (direction),

Fig. 3

shows the order of the sequenced consignments in the stacking compartments at 800 stops,

Fig. 4

shows the order of the sequenced shipments in the containers at 800 stops.

Fig. 1 shows schematically a letter sorting system for performing the method according to the invention, in which a number of stacking compartments 1 opposite a conveyor 2, with which the mail items 3, which are filled in transport container 4 have been transported to the input module 5. A transhipment bridge 6, which is arranged between the stacking compartments and the conveying device and can be moved along the row of stacking compartments 1, as is known, for example, from DE 42, is used for fast and safe reloading of the mail items from the stacking compartments 1 into the containers 4 and the subsequent transport to the conveying device 2 36 507 is known.

For simplification, the invention is described below using the example of sequencing in two sorting steps, since it is obvious to the person skilled in the art how to generalize the method for more than two sorting steps. As usual, the first sorting process is based on the least significant digit (LSD). The sorting plan is designed in such a way that the individual stacking compartments are prevented from becoming full. Such optimization is possible because experience has shown that the mail volume for certain destinations fluctuates only to a limited extent around statistical averages, which can be determined by measurements and used as the basis for the sorting plan. According to the method of the invention, no compartment is emptied during the first sorting process. At the end of the sorting process, the consignments are reloaded directly from the stacking compartment 1 into the containers 4 by means of the reloading bridge 6, successive compartments being emptied one after the other into a container until it is full. The transfer bridge forms a continuous glide path between a stacking compartment and the conveyor arranged opposite. In this way, the formation of partially filled containers is largely avoided, which also minimizes any problems with the overturning of stacks of mail items within the containers. The filled containers are arranged one behind the other in the conveyor 2. A conveyor belt 2 is preferably provided for this, the width of which corresponds approximately to the width of the containers used. The emptying of the compartments into the containers and the arrangement of the containers within the conveyor or on the conveyor belt 2 takes place in sequence. For example, if the LSD contains the elements a, b, c, d, e, f, g, h, i, k in descending order, the compartments are emptied in the order k, i, as shown in FIG. 1 , h, g, f, e, d, c, b, a, and in each container the items are arranged so that the highest elements of the LSD are stacked at the end of the container, the lowest at the front. The containers are placed on the conveyor belt so that the end of a new container placed on the conveyor belt is adjacent to the front of a container already on the conveyor belt. Such an arrangement is preferably achieved in that the transfer bridge has a funnel-shaped asymmetrical extension. This forced arrangement and conveyance of the containers prevents the order of the containers and thus the sequence integrity from being disturbed. The specified type of reloading is implemented in a letter sorting system according to FIG. 1 as follows: The reloading bridge 6 is moved by an operator along the row of stacking compartments, in such a way that the sequence k, i, h, g, f, e, d , c, b, a of the stacking compartments is moved, ie from right to left in FIG. 1. The operator goes behind the bridge 6, lifts the separating knife that is usually used in the stacking compartments with the right hand to stabilize the mail items, supports the stacked items with the left hand, sets the separating knife back into the starting position and then pushes the stack of mail items with both hands in the container on the bridge. If the stack of items no longer fits into the space available in the container, only part of the stack is first removed from the compartment and the rest secured with the separating knife. The filled container is pivoted onto the conveyor belt, which in the case of FIG. 1 corresponds to a pivoting movement of the operator to the left, so that the item last inserted into the container is on the side of the container facing the input module. Then the Operator an empty container and begins to fill it with the remaining shipments. The conveyor belt 2 preferably ends in front of the input module so that the containers can simply be pushed into the module or reloaded.

In the second sorting process, the mail items are sorted according to the most significant digit (MSD) and stored in the stacking compartments, whereby an appropriately optimized sorting plan ensures that the stacking compartments do not overflow in the second sorting process. After completing the sorting run, the compartments are emptied into the containers in the same way and the containers are placed on the conveyor belt as in sorting run 1. The containers are removed from the sorting belt in order, converted into appropriate carts and sent for further processing.

Of course, the method according to the invention is not tied to the use of containers. Rather, it is possible to remove the mail items directly from the stacking compartments 1 after the sorting aisle 1 and to push them onto the conveyor belt 2 via a reloading bridge so that the mail items are then fed to the input module in sequence. All that is necessary for this is to ensure that the mail stacks lie snugly against one another on the conveyor belt 2, so that the mail items are prevented from falling over. This can simply e.g. can be achieved by a correspondingly controlled tracking of the conveyor belt 2, through which the mail items 3 lying on the conveyor belt 2 are brought to the transfer bridge 6 when the respective pair of stacks is emptied.

In the following, the dimensioning of a sorting system with 200 stacking compartments with a respective stacking capacity of 350 consignments is illustrated in the case of 2,000 or 1,500 consignments per deliverer.

In a system with 200 stacking compartments with 350 loads each, a maximum of 70,000 consignments can be processed in one sequencing run. In order to have reserves for different consignment thicknesses and compartments that have to be filled differently, only 70% of the maximum capacity, i.e. approx. 50,000 consignments, is used. It is assumed that each deliverer has to operate 800 stops. This means that, for example, if there are 2000 consignments per deliverer, 25 deliverers are required per sequencing run. With 200 stacking compartments, a maximum of 200 x 200 stops is known (see, for example, Proceedings USPS Advanced Technology Conference, Washington, December 2, 1992, pages 1061-1074). The following table summarizes the situation for the different number of shipments per deliverer specified above. example A B Shipments / deliverers * 2,000 1,500 Delivery stops / deliverers * 800 800 Number of deliverers per sequence run 25th 33 Total number of delivery stops 20,000 26,400 Available (200200) 40,000 40,000 * = Average values

The table shows that in example A two compartments per destination (direction) can be assigned in the first sorting cycle, in example B two compartments for every second destination. In such a case, first filled the first compartment, then switched to the second, adjacent stacking compartment. For example A, the sequencing process will be described in more detail below. In the first sorting process, the subjects are sorted 1 + 2: DSN 001, 101, 201, 301, 401, 501, 601, 701 3 + 4: DSN 002, 102, 202, 302, 402, 502, 602, 702 5 + 6: DSN 003, 103, 203, 303, 403, 503, 603, 703 etc. 199 + 200: DSN 100, 200, 300, 400, 500, 600, 700, 800 filed, the stops of the deliverer are numbered with DSN (delivery sequence number).

As already shown above, the loading of the consignments into the containers begins from behind, so that the highest values of the DSN are stacked at the end of the container, while the lowest values are stacked at the front. 2 shows for example A the content 3 of a container 4 after the unloading of compartments 1 to 6, 8 being the stacking compartment with the number 1. At the end of the container, the contents of stacking compartments 5 and 6 are stacked, while the contents of stacking compartments 1 and 2 are at the front. Therefore, if the mail is removed from the container after the first sorting process, the contents of the stacking compartment 1 are first distributed in sorting process 2, and after the sorting process 2 is located at the front end of the respective stacking compartments into which the items have been stacked.

In the second sorting step, each deliverer in example A has 8 compartments in which the items, as shown in FIG. 3, are sorted. After that, the programs with the DSN 1 - 100 in one, those with the DSN 101 - 200 in one second, etc., the consignments with DSN 701 - 800 sorted into an 8th compartment. Deliverers who only have to deliver 700 or 600 DSN need fewer subjects; with more than 800 DSN, more subjects are required. In order to achieve a sequence-correct arrangement of the mail items in containers, the goods are reloaded from the stacking compartments of FIG. 3 into the containers from right to left. The sequence of the mailings thus created in the containers is shown by way of example in FIG. 4. Again, it appears that the items with the lowest DSN are stacked in the front part of the containers and those with higher ones in the rear part of the containers.

In the method according to the invention, a suitably optimized sorting plan ensures that the compartments are only overcrowded with a low probability. In the unlikely event that an overflow does occur, two to three freely assignable overflow compartments are provided per row of stacking compartments, which are inserted into the sequence by appropriate signaling when emptying the compartment. If a stacking compartment is full, one of the free overflow compartments is assigned to this destination (direction), into which the corresponding consignments are subsequently stacked. When emptying the stacking compartments, e.g. with a flashing light, the operator is instructed to remove and acknowledge the overflow compartment. The stacking compartment display shows which overflow compartment can be removed. As a result, there are only minor exceptions to the order in which the stacking compartments are emptied, while generally no change is necessary in the course of the process.

For a particularly simple and safe emptying of the stacking compartments, the stacking container known from DE 38 23 644 with a movable bottom is preferably used. This container enables the items to be stacked directly from the stacking compartment without the items being lifted by the operator or would have to be lifted over the edge of the container. In addition, the use of these containers also enables the mail items to be pushed directly from the container into the input compartment of the input module. Because the mail items are aligned with the stacking edge within the container, it is not necessary to re-align the mail items.

To simplify matters, a sorting system with only one row of stacking compartments was assumed in the foregoing. However, multi-day arrangements of the stacking compartments are common. Accordingly, a height-adjustable transfer bridge 6 is used in the method according to the invention, in which the sliding plane of the transfer bridge can be raised or lowered to the level of the stacking compartment floors. Accordingly, each row of stacking compartments (strands) is arranged opposite a conveyor or a conveyor belt. In order to reach the height of the input device of the input module from the different heights of the conveyor belts, a movable height compensation bridge is used.

Claims (8)

1. Method for the sorting of items of mail in running sequence in several sorting runs in letter distribution installations with rows of stack boxes (1), in which

   - the sorting of the items of mail into the stack boxes (1) takes place according to a sorting plan, according to which every or almost every stack box is filled during a sorting run at most to its maximum filling capacity, wherein if a stack box (1) is filled up this is assigned to an overflow box in which the further unstacking is carried out,

   - during a sorting run the stack boxes (1) are not emptied, and

   - after each conclusion of a sorting run an unloading, which is correct in running sequence, of the items of mail from the stack boxes (1) is carried out into a conveying equipment (2) arranged opposite the stack boxes (1).
2. Method according to claim 1, characterised thereby that an unloading bridge (3) movable along the row of stack boxes (1) is used for the unloading into the conveying equipment (2) or the containers (4).
3. Method according to claims 1 - 2, characterised thereby that the containers (4) during the unloading are filled each time to their maximum receiving capacity.
4. Method according to claims 1 - 3, characterised thereby that a signalling visible to an operator is carried out if an unstacking is effected in an overflow box.
5. Method according to claims 1 - 4, characterised thereby that more than one stack box (1) is assigned to a destination.
6. Method according to claims 1 - 5, characterised thereby that the containers (4) are brought into a conveyor belt (2) for further processing of the item of mail after unloading has been carried out.
7. Method according to claims 1 - 6, characteised thereby that containers (4) with movable box bases are used for a direct stacking in of the items of mail.
8. Process according to claims 1 to 7, characterised thereby that in case of a multi-storey arrangement of the stack boxes (1) an unloading is carried out onto conveyor belts arranged one above the other.

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