EP1647338A1

EP1647338A1 - Method and system for sorting products in accordance with orders therefore

Info

Publication number: EP1647338A1
Application number: EP05077260A
Authority: EP
Inventors: Leonardus Jacobus Mous Sixtus; Bruno Van Wijngaarden
Original assignee: Vanderlande Industries Nederland BV
Current assignee: Vanderlande Industries BV
Priority date: 2004-10-12
Filing date: 2005-10-06
Publication date: 2006-04-19
Anticipated expiration: 2025-10-06
Also published as: DE602005003894D1; ES2298929T3; DE602005003894T2; ATE381390T1; NL1027227C2; EP1647338B1

Abstract

The invention relates to a method for operating a system for sorting products in such a manner that individual collections of different products as specified on orders therefore are formed, as well as to such a system. The method comprises the steps of supplying different products to the sorting device, determining means determining the type of products that are to be supplied or have been supplied, order processing means processing orders for collections of different products, control means delivering control signals so as to have products delivered to discharge stations, the control means associating orders for collections of different products with respective discharge stations, so that products associated with a specific order will be delivered only to the associated discharge station, and the control means delivering control signals such that products of a particular type for a specific order will not be delivered to the associated discharge station until all products of another type for the order in question have been delivered to the associated discharge station.

Description

The present invention relates to a method for operating a system for sorting products in such a manner that individual collections of different products as specified on orders therefore are formed, said system comprising a sorting device for sorting products, at least one supply station for supplying products to be sorted to the sorting device, a number of discharge stations for discharging sorted products from the sorting device, determining means for determining the type of products to be sorted as supplied to the sorting device by said at least one supply station, order processing means for processing orders for collections of different products, and control means for delivering control signals to the sorting device at least partially on the basis of information signals from the determining means and from the order processing means so as to cause the sorting device to deliver products to the discharge stations, said method comprising the steps of

said at least one supply station supplying different products to the sorting device,
said determining means determining the type of products that are to be supplied or have been supplied to the sorting device,
said order processing means processing orders for collections of different products, and
said control means delivering control signals to the sorting device, at least partially on the basis of information signals from the determining means and from the order processing means, for causing the sorting device to deliver products to the discharge stations.

It is known to have the supplying of, for example, supermarkets, but also other types of shops or institutions, take place from a distribution centre. In such a situation, suppliers of products do not supply the shops directly but via the distribution centres, where a major sorting operation is to be carried out, therefore, in order to provide all shops with the right products. A major logistic advantage of this system is that the shops are supplied by only one party, and that for a large number of different products at the same time, rather than having to deal directly with individual suppliers. The advantage of this system for the suppliers is that they only need to deliver their products at the distribution centre rather than having to approach all the shops that are supplied by the distribution centre.
Within the distribution centre, use is made of a sorting device, such as a tilting sorter or a cross belt sorter, which types of sorters are well-known to those skilled in the art and which comprise a conveyor, usually a circular conveyor. Products delivered at the distribution centre by suppliers are placed on the sorting device by low-skilled personnel, in principle in random order, with the type of product being determined in an automated manner, for example by means of a bar code reader. A number of discharge stations branch off the circular conveyor, which discharge stations are usually in the form of a gravity conveyor or a roller conveyor, onto which products are moved from the circular conveyor. The eventual collection of different products takes place at the downstream end of the discharge stations, the products being collected in accordance with orders for such collections. The shops that are supplied from the distribution centre in question communicate such orders to an order processing system associated with the distribution centre, usually in an automated manner.
A major practical drawback of the way in which sorting systems at distribution centres are operated is connected with the fact that the sorting device delivers products associated with a specific order in random order to a discharge station. This implies that said products are deposited in random order in a collecting container, such as a cart, which is eventually transported to a shop on a lorry. Because of the random order of the contents of said cart, the subsequent sorting thereof by operators at the shop takes relatively much time, since the same type of products may be located at different positions in the cart, requiring staff to move a great deal within the shop and even return to the same location within the shop more than once with the cart.
This drawback is recognized in European patent application EP 1 265 174 A1, from which the method as referred to in the introductory paragraph is known. Said document discloses a cross-belt sorting device from which, by way of example, four gravity conveyors branch off. The control means first make an analysis, based on information signals from the order processing means, of the distribution of the total number of products as ordered in accordance with four orders. If the total number of products of a particular type being ordered is lower than a predetermined threshold value (a threshold value of 1 is used in the example), the transverse belt conveyor will deliver said product to a specifically designated one of the aforesaid four gravity conveyors. The other three gravity conveyors are exclusively reserved for those products being ordered in an amount higher than the threshold value, in which connection it is noted that the products in question are collected in groups on one of the three gravity conveyors. This implies that if the number of products of a particular type that have been collected on a particular gravity conveyor is smaller than the total number of products of that type that have been ordered, said gravity conveyor will not be available for discharging other types of products. Consequently, it is indicated in EP 1 265 174 A1 that products are to be placed on the endless conveyor of the sorting device in groups as much as possible so as to have this process proceed in an efficient manner. Present at the downstream end of the gravity conveyors is an operator, who takes the products from the downstream end of the gravity conveyors and collects them in one of four transfer carts disposed beside each other, with the operator in question being stationed between the transfer carts and the gravity conveyors. The operator in question must find out or at least be informed about the required distribution of products over the various transfer carts so as to obtain a collection of products as specified by the orders.
The present invention, too, aims at sorting products being ordered in such a manner that the sorting of products present in containers in which a collection of products as specified by an order has been collected, which takes place in a shop of the like, can proceed in an efficient manner.
An important drawback of the use of a method as disclosed in EP 1 265 174 A1 is that a second, manual sorting operation must take place at the downstream end of the gravity conveyors. The operator in question is expected to distribute the products that arrive at the downstream end of the gravity conveyors over various transfer carts. Errors may occur during this operation, of course, whilst in addition higher demands are made on the skills of the operator in question. Apart from that, the execution of a second, manual sorting operation involves additional labour costs, whilst moreover additional space is required in order to enable the operator to move between the downstream ends of the gravity conveyors and the transfer carts in a comfortable manner. Furthermore it stands to reason that the distance to be covered between the ends of the gravity conveyors and the transfer carts will increase as the number of gravity conveyors and/or the number of transfer carts in which products are to be collected increases. For that reason it is proposed in EP 1 265 174 A1 to (virtually) arrange a number of adjacent (for example four or eight) gravity conveyors in groups in the case of large systems comprising dozens of gravity conveyors and transfer carts, so as to keep the distance or distances the operators have to cover between the gravity conveyors and the transfer carts within bounds as much as possible. In addition to that, a correct operation of the system according to EP 1 265 174 A1 preferably requires that products be supplied to the sorting device in groups, the magnitude of the group preferably not exceeding the total number of products being ordered. This means that an extra intellectual effort is required from the operators engaged in supplying products to the sorting device on the supply side of the sorting device as well.
The object of the present invention is on the one hand to collect products in collecting containers in an order such that the eventual unloading of the collecting containers can take place with high level of efficiency. This implies that the aim is to collect products of the same type associated with a specific order in groups as much as possible. To that end, the method according to the invention is characterized by the steps of

the control means associating orders for collections of different products with respective discharge stations, so that the sorting device will deliver products associated with a specific order only to the associated discharge station,
the control means delivering control signals to the sorting device such that the sorting device will not deliver products of a particular type for a specific order to the associated discharge station until the sorting device has delivered all products of another type for the order in question to the associated discharge station.

Associating orders with respective discharge stations in accordance with the invention achieves that a second, manual sorting operation is not needed, but that the products can be collected at the downstream end of each of the discharge stations on a collecting container, such as a transfer cart, which is logistically linked one on one with the discharge station in question. On the one hand this requires less intelligence from the operator in question than from the operator at the corresponding position in EP 1 265 174 A1, whilst in addition the distance to be covered by products between the discharge chutes and the collecting containers is considerably smaller. Possibly, the transfer to a collecting container can take place in an automated manner. The control signals specific to the invention ensure that the sorting device will not deliver products associated with a specific order to the associated discharge station in random order but rather in groups. This achieves that said products will also be collected in groups on the collecting container and eventually can be unloaded in groups at the eventual destination, so that this will take relatively little time.
To prevent a sorting device from delivering products to a specific discharge station more quickly than that said products can be handled at the downstream end of the discharge station, it is preferable that the control means deliver control signals to the sorting device such that the sorting device will alternately deliver products of the type in question to various discharge stations.
Furthermore it is preferable that the control means determine the magnitude of the group of orders for which one product or a number of products of the type in question are to be collected at a particular point in time on the basis of the information signals from the order processing means, after which, if the magnitude of the group exceeds a predetermined threshold value, the control means will select a subgroup from said group, the magnitude of which subgroup equals said threshold value, after which the control means will deliver control signals such that the sorting device will alternately deliver the products of the type in question only to the discharge stations that are associated with the orders of the subgroup. This reduces the risk of the discharge of other types of products being stopped as a result of a (too) large number of discharge stations awaiting the arrival of products of a particular type, which might lead to the conveyor of the sorting device "filling up". The threshold value might be determined in dependence on the total demand for the product in question, for example. If a large number of orders include an order for a particular product, the threshold value may be relatively high, whilst a lower threshold value will preferably be selected in the case of a relatively low number of products being ordered, and in an extreme case the threshold value will be 1.
To have the sorting process proceed in the most constant way possible, it is preferable that, once the number of products of a particular type that have been delivered to a discharge station corresponds to the number of products of the type in question as specified in the associated order, the control means remove the order in question from the subgroup and add a new order, for which products of the type in question must be collected as well, to the subgroup. In this way the magnitude of the subgroup is maintained at a constant level, unless the number of outstanding orders ordering one product or a number of products of a particular type falls below the threshold value or if the discharge stations associated with orders for which products of the type in question need to be collected yet are still engaged in receiving products of another type.
Yet another improvement of the sorting process as regards the ease with which a collected order can be sorted at the final destination again can be achieved if the order processing means determine the order in which products of different types are to be collected for a specific order and the control means deliver control signals such that the sorting device will deliver the products to the associated discharge station in the order in question.
The present invention furthermore relates to a system for sorting products in such a manner that individual collections of different products as specified on orders therefore are formed, said system comprising a sorting device for sorting products, at least one supply station for supplying products to be sorted to the sorting device, a number of discharge stations for discharging sorted products from the sorting device, determining means for determining the type of products to be sorted as supplied to the sorting device by said at least one supply station, order processing means for processing orders for collections of different products, and control means for delivering control signals to the sorting device at least partially on the basis of information signals from the determining means and from the order processing means so as to cause the sorting device to deliver products to the discharge stations. Such a system is known from EP 1 265 174 A1. To obtain the same advantages as with the method according to present invention, the sorting system according to the invention is characterized in that the control means are adapted to associate orders for collections of different products with respective discharge stations, so as to have the sorting device deliver products associated with an order only to the associated discharge station, and to deliver control signals to the sorting device such that the sorting device will not deliver products of a particular type for a specific order to the associated discharge station until the sorting device has delivered all products of another type for the order in question to the associated discharge station.
Further preferred embodiments of the sorting system according to the invention are defined in the claims, whilst the advantages achieved by using the respective preferred embodiments have already been explained in the foregoing with reference to the corresponding preferred embodiments of the methods according to the invention.

DESCRIPTION OF THE FIGURE

The invention will now be explained in more detail by means of a description of a preferred embodiment of the invention, in which reference is made to the single figure, which schematically shows the layout of a distribution centre.
The distribution centre 1 comprises a hall 2 with exterior walls 3. A sorting device 4 is disposed in said hall. The sorting device 4 comprises an endless conveyor 5, on which products can be transported in a circular path in the direction indicated by the arrow 6. A number of parallel supply conveyors are provided for supplying products to the conveyor 5, onto which supply conveyors operators can place products to be sorted, after which supply conveyors 7 supply said products to the endless conveyor in 5 in an automated manner. The products that are placed on the supply conveyors 7 originate from buffer locations 8 located at a supply side 9 of the hall 2. To fill the buffer locations 8, unloading locations are provided at the outer side of the supply side 9 of the hall 2, where trucks 10 from suppliers can unload products, which are collected at the buffer locations 8.
Discharge conveyors embodied as parallel gravity conveyors 11 are provided for discharging products from the conveyor 5, which gravity conveyors branch off the endless conveyor 5 at right angles on the side opposite the side to which the supply conveyors 7 connect to the conveyor 5. Collecting carts 12 are positioned at the downstream end of the gravity conveyors 11. Collecting locations 14 are provided at the discharge side 13 of the hall 2 opposite the supply side 9 thereof, at which collecting locations collecting carts 12 filled with products can be collected in groups so as to be carried off in groups by trucks 15 for distributing the sorted products to customers, such as shops.
Within the framework of the present invention, the exact type of sorting device 4 is not relevant. It may conceivably, but not exclusively, be configured as a cross-belt sorter or a tilting sorter, for example, as known to those skilled in the art. Alternatively it would be possible to use pusher elements that push products off the conveyor 5 at the location of the individual gravity conveyors 11. It is of importance however that the sorting device 4 is capable of automatically delivering products to the gravity conveyors 11.
The distribution centre, more specifically the sorting device 4 thereof, is provided with a control system 16 for controlling the same, which control system delivers control signals 17 to the conveyor 5. To provide the control system 16 with information regarding the type of product that has been loaded onto the conveyor 5 via the supply conveyors 7, the sorting device 4 furthermore comprises a detection station 19, such as a bar code reader, which is capable of acquiring information regarding the type of products that passes the detection station 19 on the conveyor 5 and of passing on information signals 18 comprising such information to the control system 16. Alternatively, a detection system might be provided beside every supply conveyor 7.
In addition to that an order processing system 20 is provided, which processes information 22 about orders, more specifically information as regards the type and the number of products as specified by the respective orders that are to be collected for a specific customer, and thus in a specific collecting container 12. The control system 16 provides the coordination that is required for moving products that have been supplied to the conveyor 5 via the supply conveyors 7 onto the correct gravity conveyor 11, so that collections of products as specified by corresponding orders therefore are formed at the ends of the gravity conveyors 11, which collections will eventually be transported to a customer in a collecting container 12 on a truck 15.
Specific to the invention is the manner in which said control takes place. This can be best illustrated by means of an example, starting from three different types of products A, B, C and six orders I - VI. The control system 16 receives information 21 regarding the six orders I - VI from the order processing system 20 on the basis of order signals 22 from outside. In the present example, the orders are as shown in table 1. Table 1

Product → A B C

Order ↓

I 2 3 2

II 2 2 0

III 1 3 2

IV 0 0 2

V 0 2 2

VI 2 2 0
The control system 16 associates each order I - VI with a gravity conveyor 11, which gravity conveyors will be indicated 11-I - 11-VI. With systems as used in practice, which may comprise dozens of gravity conveyors 11, for example, said gravity conveyors 11-I - 11-VI may be distributed at random over the total number of gravity conveyors 11.
The products A, B, C are placed on the various supply conveyors 7 from the buffer locations 8 in random order and land on the endless conveyor 5 in random order. Upon passage of a product, the detection system 19 determines whether said product is product A, B or C and delivers this information to the control system 16 in the form of an information signal 18. The order in which the products A, B, C pass the detection system is shown by way of illustrative example in the second column of table 2.
Besides being adapted to associate a gravity conveyor 11 with an order, so that all products being discharged over a gravity conveyor will be intended for the order that is associated with the gravity conveyor in question, the control system is also adapted to ensure that the sorting device 4 be used in such a manner that the sorting device 4 will not deliver products of a particular type A, B or C for a specific order to the associated discharge station until the sorting device has delivered all products of another type A, B or C for the same order to the associated discharge station. In doing so, the control system 16 uses a threshold value for the number of gravity conveyors 11 to which products of a particular type are simultaneously supplied. Said threshold value is 2 in the present example.
From table 1 it can be readily derived that at least one product A must be collected for four of the six orders, whilst at least one of the respective products B and C must be collected for five of the six orders. The threshold value functions to prevent situations in which a relatively large number of gravity conveyors 11 are awaiting the arrival of the same product A, B or C, which would lead to the gravity conveyors in question not being available for receiving other types of products A, B or C. Once a gravity conveyor 11 has been provided with the total number of products of a particular type A, B or C as specified by the order associated with the gravity conveyor in question, another gravity conveyor can be added to the subgroup of gravity conveyors 11 to which the product A, B or C in question is supplied, whilst the gravity conveyor that is sufficiently filled with the product A, B or C in question becomes available for receiving another product type A, B or C.

Column 3 of table 2 shows the manner in which the products A, B and C that have been supplied in random order are successively discharged to the various gravity conveyors 11 by the sorting device 4. Looking at product C, for example, we see that the control system 16 initially uses the gravity conveyors 11-I and 11-VI for the orders I and VI, respectively, as a subgroup of gravity conveyors that receive product C, in spite of the fact that, according to the associated orders III and V, the gravity conveyors 11-III and 11-V should receive products C as well. At serial number 9, the second product C is discharged via the gravity conveyor 11-I, so that all the products C that are required for order I have been delivered to the gravity conveyor 11-I. Subsequently, the control system will replace the gravity conveyor 11-I from the subgroup for product C by the gravity conveyor 11-III the moment a next product C arrives at serial number 11. Theoretically, said replacement might take place sooner after serial number 9, but in that case there will be less opportunity for the control system 16 to respond to the current supply of products. Gravity conveyor 11-III receives its first product C at serial number 14, whilst gravity conveyor 11-I is assigned to the subgroup of gravity conveyors 11 that receive product B (serial number 13). At that moment the gravity conveyors 11-I and 11-II belong to the subgroup that is to receive products B, since the gravity conveyors 11-III, 11-V and 11-VI have already been provided with the full number of products B according to the orders III, V and VI, respectively, for serial number 13. Within the subgroups, the products are alternately distributed over the various gravity conveyors 11 that belong to the subgroup, so that the supply of products A, B, C to the various gravity conveyors 11 will be distributed over the gravity conveyors 11 as evenly as possible.

Table 2

Serial number	Product	Gravity conveyor
1	C	11-I
2	A	11-II
3	B	11-III
4	B	11-V
5	C	11-IV
6	B	11-III
7	B	11-V
8	B	11-III
9	C	11-I
10	B	11-VI
11	C	11-IV
12	B	11-VI
13	B	11-I
14	C	11-III
15	A	11-VI
16	A	11-II
17	C	11-V
18	B	11-II
19	C	11-III
20	B	11-I
21	B	11-II
22	C	11-V
23	B	11-I
24	A	11-VI
25	A	11-I
26	A	11-III
27	A	11-I

Table 3 shows the final result of the sorting process by indicating in the second column the order in which the gravity conveyors 11-I - 11-VI mentioned in the first column have received the products A, B and C. A comparison between the second column of table 3 and the content of table 1 shows that the correct products have been collected on the gravity conveyors. In addition to that it can be directly inferred from table 3 that the products A, B and C have only been unloaded on the gravity conveyors in groups by the sorting device 4. Table 3

Gravity conveyor

11-I C C B B B A A

11-II A A B B

11-III B B B C C A

11-IV C C

11-V B B C C

11-VI B B A A
If the orders I - VI were to comprise information regarding the order of collecting the products A, B and C as well, this information, too, could be processed by the order processing means 20 and be passed on to the control system 16 in the form of an information signal 21, whereupon the control system 16 could also use this information for driving the conveyor 5 with control signals 17 in such a manner that the collection of products A, B and C will take place via the gravity conveyors 11 in the order as specified by the respective orders I - VI.

Claims

A method for operating a system for sorting products (A, B, C) in such a manner that individual collections of different products as specified on orders (I - VI) therefore are formed, said system comprising a sorting device (5) for sorting products, at least one supply station (7) for supplying products to be sorted to the sorting device, a number of discharge stations (11) for discharging sorted products from the sorting device, determining means (19) for determining the type of products to be sorted as supplied to the sorting device by said at least one supply station, order processing means (20) for processing orders for collections of different products, and control means (16) for delivering control signals (17) to the sorting device at least partially on the basis of information signals from the determining means (18) and from the order processing means (21) so as to cause the sorting device to deliver products to the discharge stations, said method comprising the steps of
- said at least one supply station supplying different products to the sorting device,

- said determining means determining the type of products that are to be supplied or have been supplied to the sorting device,

- said order processing means processing orders for collections of different products, and

- said control means delivering control signals to the sorting device at least partially on the basis of information signals from the determining means and from the order processing means so as to cause the sorting device to deliver products to the discharge stations,
characterized by the steps of
- the control means associating orders for collections of different products with respective discharge stations, so that the sorting device will deliver products associated with a specific order only to the associated discharge station,

- the control means delivering control signals to the sorting device such that the sorting device will not deliver products of a particular type for a specific order to the associated discharge station until the sorting device has delivered all products of another type for the order in question to the associated discharge station.
A method according to claim 1, characterized by the step of the control means delivering control signals to the sorting device such that the sorting device will alternately deliver products of the type in question to various discharge stations.
A method according to claim 1 or 2, characterized by the steps of
- the control means determining the magnitude of the group of orders for which one product or a number of products of the type in question are to be collected at a particular point in time on the basis of the information signals from the order processing means,

- the control means selecting a subgroup from the group if the magnitude of said group exceeds a predetermined threshold value, the magnitude of which subgroup equals said threshold value,

- the control means delivering control signals such that the sorting device will alternately deliver the products of the type in question only to the discharge stations that are associated with the orders that form part of the subgroup.
A method according to claim 3, characterized by the steps of the control means
- removing an order from the subgroup as soon as the number of products of a particular type that have been delivered to a discharge station corresponds to the number of products of the type in question as specified in the associated order, and

- adding a new order, for which products of the type in question must be collected as well, to the subgroup.
A method according to any one of the preceding claims, characterized by the steps of
- the order processing means determining the order in which products of different types are to be collected for a specific order, and

- the control means delivering control signals such that the sorting device will deliver the products to the associated discharge station in the order in question.
A system for sorting products (A, B, C) in such a manner that individual collections of different products as specified on orders (I - VI) therefore are formed, said system comprising a sorting device (4) for sorting products, at least one supply station (7) for supplying products to be sorted to the sorting device, a number of discharge stations (11) for discharging sorted products from the sorting device, determining means (19) for determining the type of products to be sorted as supplied to the sorting device by said at least one supply station, order processing means (20) for processing orders for collections of different products, and control means (16) for delivering control signals (17) to the sorting device at least partially on the basis of information signals from the determining means (18) and from the order processing means (21) so as to cause the sorting device to deliver products to the discharge stations, characterized in that the control means are adapted to associate orders for collections of different products with respective discharge stations, so as to have the sorting device deliver products associated with an order only to the associated discharge station, and to deliver control signals to the sorting device such that the sorting device will not deliver products of a particular type for a specific order to the associated discharge station until the sorting device has delivered all products of another type for the order in question to the associated discharge station.
A system according to claim 6, characterized in that the control means are adapted to deliver control signals to the sorting device such that the sorting device will alternately deliver products of the type in question to various discharge stations.
A system according to claim 6 or 7, characterized in that the control means are adapted to
- determine the magnitude of the group of orders for which one product or a number of products of the type in question are to be collected at a particular point in time on the basis of the information signals from the order processing means,

- select a subgroup from the group if the magnitude of said group exceeds a predetermined threshold value, the magnitude of which subgroup equals said threshold value,

- deliver control signals such that the sorting device will alternately deliver the products of the type in question only to the discharge stations that are associated with the orders that form part of the subgroup.
A system according to claim 8, characterized in that the control means are adapted to remove an order from the subgroup as soon as the number of products of a particular type that have been delivered to a discharge station corresponds to the number of products of the type in question as specified in the associated order, and add a new order, for which products of the type in question must be collected as well, to the subgroup.
A system according to any one of the claims 6-9, characterized in that the order processing means are adapted to determine the order in which products of different types are to be collected for a specific order, and in that the control means are adapted to deliver control signals such that the sorting device will deliver the products to the associated discharge station in the order in question.