Process for sorting objects

A method for sorting objects using a continuous loop conveyor sorting system having two or more feeders. In one embodiment, the method includes sorting a batch of objects to form a first group of objects and a second group of objects, using a first feeder to feed all of the objects from the first group onto the conveyor, using a second feeder to feed all of the objects from the second group onto the conveyor, removing the objects from the first group from the conveyor prior to the any of the objects reaching the point at which the second feeder feeds objects onto the conveyor, and removing the objects from the second group from the conveyor prior to the any of the objects reaching the point at which the first feeder feeds objects onto the conveyor.

BACKGROUND

1. Field of the Invention

The present invention relates to systems and methods for sorting objects (e.g., parcels or other objects)

2. Discussion of the Background

There are numerous organizations that sort objects by some object attribute (e.g., purchase order, stock number, destination point or any number of other attributes of the object). In many cases, the sorting machines involved do not have enough sorting fidelity (e.g., number of outputs) to provide 100% sorting capacity within a single sorting process. Typically, this is addressed through the creation of primary and secondary sort plans designed to create one level of separation on the primary sort and then a finer degree of separation on the secondary sort(s).

In some cases, such as mail processing, matched sort plans are used to sequence the mail into a specific order such as the delivery sequence of the mail carrier. Typically, these are two, or three pass sorting operations.

Because it may take more than one sort to separate, or sequence, objects to the desired level of separation it is important that the base throughput of the sorting machinery be as high as possible to offset the time consumed in performing multiple passes, or sorts. For example, if a system operates at 30,000 objects per hour and must perform two sorts to create the sort fidelity required, then the operational throughput of the sorting process can be no better than 15,000 objects per hour (set up time, system sweeping and other ‘overhead functions’ degrade this further).

There are some sorting systems that are configured to produce throughputs higher than the base system with a simplified configuration (see e.g., U.S. Pat. No. 6,889,814). Usually, systems of this type have a continuous loop conveyor that has a first feeder (or “induction station”) located at one “end” of the conveyor and a second feeder located at the opposite “end” of the conveyor. The feeders feed objects onto the conveyor, and the objects are then conveyed to an output section (or “discharge station”) that is associated with the object. By feeding objects into the system at opposite ends of the system, the system has multiple opportunities to use the sorting mechanism (e.g., tilt tray, cross belt, carousel, or other sorting mechanism) as some of the objects are loaded at one end and sorted prior to reaching the second feeder allowing for an average of more than one sort per cycle of the carrying mechanism.

Configuring the sort plan such that the high volume sort locations are on one side of the machine can enable even higher utilization for the second set of feeders. Unfortunately, these types of system have limitations that are driven by the random nature of the material being presented to the feeders.

Ideally, one would like to process such a system at the theoretical maximum possible throughput (e.g., twice the base throughput for a system using two sets of feeders). In doing so, the system would be run at the maximum possible efficiency, operating at half the speed of a single feeder system and producing the same throughput. The capability to operate at slower processing speeds reduces the number of errors introduced into the process and minimizes potential damage to the product.

SUMMARY OF THE INVENTION

The present invention provides methods for sorting objects. In some embodiments, the methods employ a sorting system having a continuous loop conveyor and two or more feeders for depositing objects onto the conveyor.

In one embodiment, the method includes: (a) sorting a batch of objects to form a first group of objects and a second group of objects, (b) using a first feeder to feed all of the objects from the first group of objects onto the conveyor, (c) using a second feeder to feed all of the objects from the second group of objects onto the conveyor, (d) removing from the conveyor the objects from the first group of objects prior to the any of the objects reaching the point at which the second feeder feeds objects onto the conveyor, and (e) removing from the conveyor the objects from the second group of objects prior to the any of the objects reaching the point at which the first feeder feeds objects onto the conveyor.

The above and other features and advantages of the present invention, as well as the structure and operation of preferred embodiments of the present invention, are described in detail below with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1illustrates a conventional object sorting system100having multiple feeders. In the embodiment shown, system100includes: a continuous loop conveyor path160, two feeders (feeder1and feeder2) that feed objects onto the conveyor path160, and two output sections (output section1and output section2) that receive the objects placed onto the conveyor path.

Preferably, as shown, feeders1and2and output sections1and2are arranged around conveyor160so that (1) all objects180introduced onto conveyor160from feeder1will reach output section1prior to reaching the point at which feeder2introduces objects180onto conveyor160, and all objects180introduced onto conveyor160from feeder2will reach output section2prior to reaching the point at which feeder1introduces objects180onto conveyor160.

Conventionally, each object180placed onto the conveyor path160is assigned to only one of the output sections (a sort plan may be used to assign objects to output sections). For example, all objects that are to be shipped to New York City may be assigned to output section1and all objects to be shipped to Chicago may be assigned to output section2. Thus, when an object to be shipped to New York City is placed on conveyor160, the object will eventually be conveyed to output section1, at which point the object is removed from conveyor160and placed, for example, into an output bin190of the first output section. Similarly, when an object to be shipped to Chicago is placed on conveyor160, the object will eventually be conveyed to output section2, at which point the object is removed from conveyor160and placed, for example, into an output bin195of the second output section. In this manner, the NYC objects can be separated from the Chicago objects.

Conventionally, system100is operated such that objects assigned to different output sections are introduced onto conveyor160using the same feeder. For example, in conventional sorting processes, borrowing from the example above, feeder1and/or feeder2may be used to place onto conveyor160the objects destined for NYC as well as the objects destined for Chicago. In such a situation, at least some of the objects will travel almost the entire conveyor loop before being removed from the conveyor. This is inefficient.

The present invention solves this inefficiency. Lets assume we have a generally randomly ordered set of objects, wherein the set of objects includes (1) a first subset of objects that share a first common attribute (e.g., parcels destined for a city on the East Coast) and (2) second first subset of objects that share a second common attribute (e.g., parcels destined for a city on the West Coast), and lets further assume that we want to place (1) all East Coast parcels into one of the outputs of output section1and (2) all of the West Coast parcels into one of the outputs of output section2. Given this scenario,FIG. 2is a flow chart illustrating a process200according to an embodiment of the invention.

In step202, a sort plan is created that assigns all of the objects having the first attribute (e.g., the East Coast parcels) to output section1and assigns all of the objects having the second attribute (e.g., the West Coast parcels) to output section2.

In step204, the set of objects is obtained and physically separated into at least a first subset of objects and a second subset objects, wherein the first subset includes all the objects having the first attribute and the second subset includes all the objects having the second attribute.

In step206, the subset of objects having the first attribute are positioned at the input110of feeder1and then fed onto conveyor160by feeder1.

In step207, the objects fed onto conveyor160by feeder1are transported by conveyor160to the output section1. Because of the positions in which the feeders and output sections are arranged around conveyor160, these objects will not pass the point at which feeder2places objects onto conveyor160because these objects are removed from conveyor at output section1.

In step208, the subset of objects having the second attribute are positioned at the input112of feeder2and then fed onto conveyor160by feeder2.

In step209, the objects fed onto conveyor160by feeder2are transported by conveyor160to output section2. Because of the positions in which the feeders and output sections are arranged around conveyor160, these objects will not pass the point at which feeder1places objects onto conveyor160because these objects are removed from conveyor at output section2.

Process steps206and207may be performed at the same time as process steps208and209.

The above process enables sorting system100to operate at an improved fidelity. Specifically, the process enables system100to process at full throughput on each feeder. If the transport mechanism (i.e., conveyor160) of system100were traveling at 10,000 objects per hour, then this configuration could sort at 20,000 objects per hour during the secondary sorts.

System100could be used to perform step204, by feeding the set of objects using feeders1and2and separating the objects into the two subets, or any other sorting system capable of handling the objects could perform the primary (or “first pass sort”).

Increasing the number of feeders and output sections and presorting the objects to be sorted into the appropriate subsets in a primary sort can provide for even great throughput. For example, for system300(seeFIG. 3), which has four feeders and four output sections the throughput could be quadrupled.

System300would be used in cases where an unordered set of objects includes four subsets (e.g., a set of parcels where some parcels are destined for Canada, some for Mexico, some for Europe and some for Asia). In such a situation, the unordered set of objects is sorted into the at least these four subsets such that all of the parcels for Mexico are physically grouped together, all of the parcels for Canada are physically grouped together, all of the parcels for Europe are physically grouped together, and all of the parcels for Asia are physically grouped together. Each grouping is assigned to one of the output sections and then fed onto conveyor using the feeder that is immediately upstream from the output section. For example, if the Mexico grouping is assigned to output section4, then the Mexico grouping of objects should be fed onto conveyor using feeder4, which is the feeder that is immediately upstream from output section4.

It should be noted that, even though system100includes only two feeders and two output sections, system100can be used to sort an unordered set of objects that includes more than two identifiable subsets of objects.FIG. 4is a flow chart illustrating a process400according to an embodiment wherein system100is used to sort an unordered set of objects that includes four identifiable subsets of objects. A similar process can be applied to system300to enable it to sort an unordered set of objects that has more than four identifiable subsets.

Process400may being in step402, where a sort plan is created that assigns: (1) the first identifiable subset objects to output section1, (2) the second identifiable subset objects to output section2, (3) the third identifiable subset objects to output section1, and (4) the fourth identifiable subset objects to output section2.

In step404, the unordered set of objects is obtained and physically separated to physically separate the four subsets from the each other.

In step406, the first subset of objects is positioned at the input of feeder1and then fed onto conveyor160by feeder1.

In step407, the objects fed onto conveyor160by feeder1are transported by conveyor160to the output section1. Because of the positions in which the feeders and output sections are arranged around conveyor160, these objects will not pass the point at which feeder2places objects onto conveyor160because these objects are removed from conveyor at output section1.

In step408, after entire first subset has been conveyed to output section1and removed from the output bins of section1, the third subset of objects is positioned at the input of feeder1and then fed onto conveyor160by feeder1.

In step409, the third subset of objects fed onto conveyor160by feeder1are transported by conveyor160to the output section1.

In step411, the second subset of objects is positioned at the input of feeder2and then fed onto conveyor160by feeder2.

In step412, the objects fed onto conveyor160by feeder2are transported by conveyor160to the output section2. Because of the positions in which the feeders and output sections are arranged around conveyor160, these objects will not pass the point at which feeder1deposits objects onto conveyor160because these objects are removed from conveyor at output section2.

In step413, after entire second subset has been conveyed to output section2and removed from the output bins of section2, the fourth subset of objects is positioned at the input of feeder2and then fed onto conveyor160by feeder2.

In step414, the fourth subset of objects fed onto conveyor160by feeder2are transported by conveyor160to the output section2.

Process steps406-409may be performed at the same time as process steps411-414.

An advantage of the above processes is increased throughput. Thus, it is possible to operate conveyor160at a speed well below its maximum speed and still be able to process the same number of objects in a given time period. For example, if in a conventional system the speed of conveyor must be X in in order to process Y number of objects in a hour, with the present invention the speed may of conveyor160may be set to X/Z (Z>1) while still being able to process Y number of objects in a hour.

While the processes described herein have been illustrated as a series or sequence of steps, the steps need not necessarily be performed in the order described, unless indicated otherwise.