Method of sorting a plurality of individually conveyed articles into groups in at least one sorting step

Described is a method of sorting a plurality of individually conveyed articles in groups in at least one sorting step in a suspension-type conveyor, the articles being introduced in substantially unsorted manner into a first conveyor circle and being delivered from said circle in sorted fashion to at least one second conveyor circle, with an identification source identifying every article to be conveyed individually. To be able to use such a method in a universal manner and to accelerate the sorting process, the articles are delivered in a partial quantity containing a predetermined number in a first sorting step, independently of the loaded state of the first conveyor circle, from the first conveyor circle to the second conveyor circle as soon as the partial quantity of articles to be sorted in the first sorting step has been identified on the first conveyor circle.

BACKGROUND 
The present invention relates to a method of sorting a plurality of 
individually conveyed articles in a suspension-type conveyor. 
Such a method is known from German patent publication DE-OS 42 26 066. The 
known method operates with a plurality of sequentially arranged circular 
conveyors on which articles to be individually conveyed are circulated. 
The articles are delivered to the first circular conveyor in a disordered 
manner or in a roughly ordered manner. After delivery of the articles to 
the first circular conveyor has been terminated, the sorting process 
starts. The desired groups are first handed over from the first circular 
conveyor to the second circular conveyor, the conveying direction being 
reversible to collect the articles on the second circular conveyor in the 
desired order at the same time. It is also possible to collect two 
different groups on the second conveyor at the same time. Furthermore, it 
is possible to couple a third circular conveyor or other circular 
conveyors with the second circular conveyor, a specific group being 
assigned to each of the circular conveyors and said circular conveyor 
being possibly designed as a storage place for said group at the same 
time. Hence, the known operating method is fixed to sorting steps. For 
instance, the sorting steps will only be taken if all of the articles to 
be sorted are present on the first circular conveyor, being sensed by the 
identification means. On the one hand, the sorting time is prolonged 
thereby; on the other hand, the known method is not of such a universal 
application that it could cope with different sorting tasks. DE 35 19 630 
C2 discloses a method and apparatus for completing products consisting of 
several parts in a storage room divided into a plurality of departments. 
This method is meant to ensure that two predetermined and associated 
articles, particularly individual articles of clothing, such as jacket and 
trousers of a suit, which are delivered at different times reach the same 
storage place. To this end, the articles are guided past an identification 
means where they are identified and where a special storage place is 
assigned to them. This information is printed on a label which is attached 
to the article. The article is then discharged onto a distribution 
conveyor which passes the article along a number of storage corridors in 
which further branched conveyors are arranged. When the article has 
reached the associated storage corridor, it is ejected from the 
distribution conveyor and moved via a branch to the predetermined storage 
place to which it is hung by hand. 
SUMMARY OF THE INVENTION 
Hence, this method is a kind of guide system which is to ensure that a 
specific article reaches a predetermined storage place over the shortest 
way possible and with maximum reliability, but it is not a method for 
sorting a plurality of individually conveyed articles in groups in at 
least one sorting step; and the articles are also not transferred from a 
first circular conveyor to a second circular conveyor. Such a method could 
certainly not cope with a sorting task which presupposes the potential 
ability to compile a substantially unlimited multitude of articles in a 
desired manner in groups, to change their sequence and to discharge them 
optionally in a delayed or accelerated manner. 
Hence, it is the object of the present invention to provide a time-saving 
method of universal application for sorting articles. 
The method of the invention is based on the idea that the sorting process 
could be accelerated considerably if, in contrast to the prior art, the 
method was no longer based on the individual articles to be sorted, but on 
a goods flow that should be optimum if possible. The most different 
sorting tasks can then be performed on such a basis without any major 
changes in the structure of the transporting device. Thanks to the design 
according to the invention, the first conveyor circle acts as a preceding 
or receiving buffer means on which articles can be placed freely and 
optionally chaotically, and which receives everything that is fed at any 
desired time. The identification means identifies every individual article 
and starts the delivery of a predetermined number of articles, which 
comply with the same criterion of selection, to the second conveyor circle 
as soon as said predetermined number of articles are positioned on the 
first conveyor circle. In an extreme case delivery of such an article can 
already be started as soon as only one of the articles has been placed on 
the first conveyor circle in accordance with the special criterion of 
selection. The other articles remain in the first conveyor circle until 
sorted according to criteria of selection they comply with. 
It is especially expedient when every other sorting step is respectively 
taken upon delivery to a separate conveyor circle, since the individual 
conveying steps can thus be performed substantially at the same time, 
which further reduces the sorting time. 
The sorting time can be even further reduced if the next sorting step is 
already started whilst the preceding sorting step has not been finished 
yet. 
The buffer capacity of the first conveyor circle can be increased and is 
adapted to the respective requirements in an improved manner. 
Additional objects and advantages of the invention will be set forth in 
part in the description which follows, and in part will be obvious from 
the description, or may be learned by practice of the invention. The 
objects and advantages of the invention may be realized and attained by 
means of the instrumentalities, steps, and combinations particularly 
pointed out in the appended claims.

In the illustrated embodiment, the suspension-type conveyor means 1 
comprises a feed zone 2, a buffer zone 3, a sorting zone 4, and a 
discharge zone 5. The feed zone 2 contains a supplier 6 which is 
expediently designed as a circular conveyor and rotates in the direction 
marked by arrows. The supplier 6 may have arranged upstream thereof a 
loading conveyor 7 which is also designed as a circular conveyor, rotates 
in the direction marked by arrows and feeds the supplier 6 with the 
articles to be conveyed. 
The suspension-type conveyor means 1 is composed of commercial conveyors, 
which need not be explained in more detail. 
For the purpose of the following description, the term "articles" is meant 
to designate both individual goods or units of goods, such as articles of 
clothing hung onto a respective hanger or ensembles (suit, costume) hung 
onto a hanger, or a plurality of goods which are jointly transported by 
one and the same conveyor means over their whole path. 
A working place 8 at which wrongly sorted articles are checked and either 
removed from the conveyor circuit in the suspension-type conveyor means 1 
or fed again via supplier 6 into the conveyor circuit is also provided in 
the feed zone 2 at another conveyor 9. 
The buffer zone 3 contains a plurality of first conveyor circles 10 which 
are formed as individual circular conveyors and of which five conveyor 
circles 10.1, 10.2, 10.3, 10.4 and 10.5 are shown. Each of said conveyor 
circles 10 is fed via supplier 6 across a respective shunt (not shown). 
In sorting zone 4, a first conveyor circle 10 is respectively followed by a 
second conveyor circle 11 which is again formed as an individual circular 
conveyor, with five second conveyor circles 11.1, 11.2, 11.3, 11.4 and 
11.5 being again shown. Each of the second conveyor circles 11 is followed 
within sorting zone 4 and via a respective shunt by a third conveyor 
circle 12, with the five third conveyor circles 12.1, 12.2, 12.3, 12.4 and 
12.5, which are formed as circular conveyors, being again shown. The third 
conveyor circles 12, too, rotate in the directions marked by arrows. 
Each of the third conveyor circles 12.1, 12.2, 12.3, 12.4 and 12.5 is 
connected via a respective shunt (not shown) to a joint discharge conveyor 
13 in the discharge zone 5. 
If necessary, a conveyor path 14 leads from the discharge conveyor 13 back 
to the supplier 6. The conveyor paths 14 may be designed as branches, as 
shown, or also as circular conveyors, if necessary, and serve to return 
either wrongly sorted or defective articles or empty conveying means when 
the articles to be conveyed are e.g. removed from their conveying means at 
the discharge conveyor 13. 
Furthermore, the suspension-type conveyor means 1 comprises an only 
schematically shown identification means 15 which is connected via a 
computer 16 to control means 17. Identification means, computer and 
control means are only shown as boxes and contain commercial components. 
The identification means 15 comprises at least one respective sensor 18 
which can be designed as a reading device for the codes, or the like, 
provided on the articles, which furnish information e.g. about the type, 
number and sequence of the articles positioned in the suspension-type 
conveyor means 1. In the illustrated embodiment, a respective sensor 18.1, 
18.2, 18.3, 18.4 and 18.5 is assigned to each of the first conveyor 
circles 10.1, 10.2, 10.3, 10.4 and 10.5. Of course, other sensors or 
reading devices may be provided at other places of the suspension-type 
conveyor means 1, e.g. in the area of supplier 6 or in the area of 
discharge conveyor 13. 
The signals of the sensors 18 are supplied by the identification means 15 
to the computer 16 which activates control means 17 according to the 
respective program. The control means 17 is at least connected to the 
shunts between the conveyor circles 10 and 11, between the conveyor 
circles 11 and 12 and between the third conveyor circle 12 and the 
discharge conveyor 13 and opens and closes the same according to 
instructions from the computer. The control means 17 can additionally 
control the shunts between the feeder 7 and supplier 6 and the supplier 6 
and the first conveyor circles 10. Moreover, the control means 17 can 
control the rotational speed of the conveyor circles. 
It is assumed that in the suspension-type conveyor means 1 articles of 
different types and in random order are to be combined in groups which 
solely contain articles of a single type in a predetermined order. The 
articles are distributed over all of the first conveyor circles 10. 10.2, 
10.3, 10.4, 10.5 via supplier 6 at random and substantially only in 
accordance with the conveying capacity of the first conveyor circles 10. 
The first conveyor circles thus serve as rough buffer means on which 
articles can be placed freely and chaotically. This ensures a high degree 
of exploitation of the circles. Each of the sensors 18.1, 18.2, 18.3, 
18.4, 18.5 identifies every individual article on the associated conveyor 
circle 10 in the course of time, so that the computer 16 can exactly 
indicate the position of every individual article on each of the first 
conveyor circles 10.1 to 10.5 in response to the conveying speed and the 
length of the conveying path at any time. 
The number of the articles in the groups to be formed are subdivided into 
predetermined partial quantities. Each of the partial quantities will 
immediately be requested from the first conveyor circles as soon as a 
number of articles corresponding to said partial quantity have been 
collected on one of the first conveyor circles 10.1 to 10.5. The shunt 
between the respective first conveyor circle 10.1 to 10.5 and the 
associated second conveyor circle 11.1 to 11.5 will be operated via 
control means 17 for ejecting purposes as soon as an article of this 
partial quantity is in the area of the shunt. 
Articles of the same type of this partial quantity are then delivered from 
the respective second conveyor circle 11.1 to 11.5 to the associated third 
conveyor circle 12.1 to 12.5 in such a manner that the articles are 
positioned on the third conveyor circles 12.1 to 12.5 already in the 
respectively desired order. During this sorting process a second partial 
quantity of articles of this type can readily be handed over from the 
corresponding first conveyor circle 10 to the associated second conveyor 
circle 11 without the sorting step between the second conveyor circle 11 
and the third conveyor circle 12 being interfered with, since the articles 
are individually identified. 
If articles of the type to be sorted are positioned on a plurality of first 
conveyor circles 10 and if all articles of this type are to be delivered 
jointly in a predetermined order, the articles which are already presorted 
in their order on the third conveyor circles 12 will be transferred via 
the correspondingly controlled shunts in such an order onto the discharge 
conveyor that the desired group of articles of one type are finally 
positioned on the discharge conveyor 13 in the predetermined order and can 
there either be removed or transported away for further handling. 
To perform a more thorough fine sorting step, the articles can also 
circulate several times, especially on the second and third conveyor 
circles 11 and 12, so that a purposeful introduction of articles is also 
possible between already collected groups on the respectively subsequent 
conveyor circle 11 or 12. 
To facilitate the sorting operation, the articles can be delivered in a 
presorted manner, instead of a chaotic manner, to the first conveyor 
circles, the presorting step being expediently performed such that a 
specific number of conveyor circles 10 are reserved for a specific type of 
articles or for specific types of articles, so that only articles of two 
types are e.g. positioned on the conveyor circle 10.1. To ensure an 
automatic feeding of buffer zone 3, the supplier 6 should be provided with 
another sensor 18.6. 
If defective articles or wrongly coded articles are detected, they can be 
conveyed from the discharge conveyor 13 via conveyor path 14 back to the 
supplier 6. It is then expediently determined by another sensor (not 
shown), e.g. by a light barrier, that such an article is returned, so that 
the shunt (not shown) between the supplier 6 and the conveyor 9 is 
operated to convey this article to the conveyor 9 and then to the working 
place 8. The article can again be introduced into supplier 6 from working 
place 8. 
Instead of the above-described automatic feeding operation, the articles 
can also be introduced manually at working place 8 or at another working 
place at feeder 7 into supplier 6 or, however, manually directly into the 
first conveyor circles 10. A combination of automatic and manual feeding 
is also possible. The joint discharge conveyor can also be dispensed with 
if the articles are directly removed at the last circular conveyor of the 
sorting zone. Instead of the illustrated groups of three circular 
conveyors, it is also possible to use groups of two circular conveyors or 
groups of circular conveyors with more than three conveyor circles. 
Moreover, every conveyor circle can consist of a plurality of circles 
having the same function and control.