WO2004024349A1

WO2004024349A1 - Method and arrangement for sorting means by a rotating drum.

Info

Publication number: WO2004024349A1
Application number: PCT/SE2003/001339
Authority: WO
Inventors: Torsten Johansson; Per-Åke PERSSON
Original assignee: POSTEN AB
Current assignee: POSTEN AB
Priority date: 2002-09-11
Filing date: 2003-08-28
Publication date: 2004-03-25
Anticipated expiration: 2005-03-11
Also published as: SE523673C2; SE0202695D0; AU2003253560A1; SE0202695L

Abstract

The invention concerns a method and an arrangement for a sorting arrangement, in particular for a sorting drum at a mail sorting facility, in which items of mail are fed with the aid of a feed belt (1) into one end wall of a rotating separation drum (4), where incoming items of mail are given a velocity and thus a spreading along the axial direction of the drum (4) in that they are fed from the feed belt (1) over a glide arrangement (9) arranged extending into the drum and tilted downwards from the feed belt (1).

Description

METHOD AND ARRANGEMENT FOR SORTING MEANS BYA ROTATING DRUM.

The present invention relates to a method and an arrangement for a sorting means, in particular for a separating drum in a mail sorting facility.

In mail sorting facilities that are present at large post terminals, the solution of the sorting of incoming mail is to an ever- increasing degree sought by means of automatic sorting. Incoming mail is emptied onto a coarse sorting belt that feeds the mail to a sorting drum. A certain manual selection of such mail as is not suitable for automatic sorting, for example, newspapers without covers and items of mail that are already damaged, takes place at the coarse sorting belt. The mail that passes onwards on the coarse sorting belt is further fed onwards to a feed belt that in turn feeds the mail through a central opening in one end wall of the above-mentioned separation drum. The separation drum is inclined downwards to a certain degree from the input end, and its inner surface is formed by extended lamellae, oriented in an axial direction and somewhat oblique, that offer at their longitudinal edges a certain distance between neighbouring lamellae, such that mail that has a thickness that is less than the opening that is formed between the lamellae can, during the rotation of the drum, fall into a collecting space under the separation drum, from where it can be led onwards for further automatic sorting. The size of the opening between the lamellae is normally of the order of 6 mm, and mail with a thickness that is greater than this is fed through the rotation of the drum and its downwards inclination to the opposite end wall, where the mail with a thickness greater than this is fed out through an opening in this end wall, where it can be processed for manual sorting. One problem associated with the separation drum that is described above that has received attention is the tendency of the items of mail to follow the rotation of the drum, whereby they are released from the wall of the drum when they have reached a certain height and fall back down to the bottom of the drum. Thus, there is a risk that heavy items of mail are in this way damaged, and furthermore, that they damage items of mail onto which they may fall. The drum normally rotates at a rate of 14 revolutions per minute. However, experiments have been carried out in reducing the rate of revolution in order to reduce damage to the items of mail, but in this case congestion of the items of mail arises in the drum and the rate of input must thus also be reduced, leading to a significantly reduced capacity. It is, on the other hand, desired to increase the capacity, and experiments have been carried out in increasing the rate of revolution and the rate of input. This has, however, led to an increase in the number of damaged items of mail and an increase in the quantity of mail that passes through the drum without being sorted.

Thus it is one aim of the present invention to achieve a method and an arrangement for a sorting means of the type described above, and in which damage to the items of mail can be reduced.

This aim of the invention is achieved with a method and an arrangement in which a glide means is arranged to lead incoming mail from the feed belt such that it obtains a velocity and thus a spreading along the axial direction of the drum. A further aim of the invention is, in addition, to be able to increase the capacity of the sorting means, such that a greater quantity of mail can be sorted in the sorting means without an increase in the quantity of subsequent manual sorting.

This further aim of the invention is achieved by reducing the rate of rotation of the drum.

The invention will now be described in more detail in the form of a non-limiting embodiment, illustrated with the aid of the attached drawings, of which Figure 1 shows in a partially cut-away perspective view a sorting means in which the method and the arrangement according to the invention can be used, Figure 2 shows a view corresponding to Figure 1 with an arrangement according to the invention mounted in it, Figure 3 shows schematically in a side view a cross-section of the input region of a separation drum with an arrangement according to the invention, and Figure 4 shows a plan of a glide plate according to one embodiment of the arrangement according to the invention.

That part of a sorting facility that is shown in Figure 1 comprises a feed belt 1 that feeds items of mail 2 into a separation unit 3. The separating unit 3 comprises a separation drum 4, which is arranged inclined along its axial direction such that it inclines downwards from the feed band 1 towards a output opening arranged in the second end wall through which items of mail that have not been sorted can be led to a handling station 5 where these items of mail can be processed for manual sorting. The separation drum 4 is covered on its inner surface with extended lamellae 6, directed along the axial direction. The lamellae 6 are oriented somewhat obliquely relative to the inner circumference of the drum 4 such that longitudinal gaps with an opening of approximately 6 mm are formed between the lamellae .

The sorting unit illustrated in the drawing is one manufactured by Siemens, model number CF992. The separation drum has a length of approximately 3.2 m and a diameter of approximately 1.5 m. The drum normally rotates at a rate of 14 revolutions per minute, although some users have increased the rate to 18 revolutions per minute in order to increase the sorting capacity.

When the separation drum 4 rotates, items of mail 2 that have been fed into the drum by the feed belt 1 will, by the rotation of the drum and its downward inclination, be transported towards the outlet opening. Items of mail 2 that have a thickness not exceeding 6 mm, which includes the great majority of all items of mail, will then glide into the longitudinal gaps between the lamellae 6 and in this way leave the separation drum 4 such that they never reach the outlet opening and the manual processing station 5. Only items of mail 2 with a thickness greater than 6 mm thus will pass through the complete length of the drum and onwards out to the manual processing station 5. Those items of mail that leave the drum through the longitudinal gaps between the lamellae 6 are collected by a collection tray 7 located under the separation drum 4 and they are fed with the aid of a output belt 8 onwards to further automatic handling.

Figure 2 shows schematically an arrangement according to the invention, in which a glide arrangement 9 is arranged in the separation drum 4 in direct association with the forwardly acting feed belt 1. The glide arrangement 9 is arranged such that it receives all items of mail that are fed upwards by the feed belt 1 and it lies tilted downwards towards the bottom of the separation drum 4 and extends a certain distance into it. The items of mail will then glide over the surface of the glide arrangement 9 down towards the bottom of the rotating separation drum 4, and they will receive a velocity in the axial direction of the drum, and the items of mail will, to a large extent, maintain this velocity when they leave the glide arrangement 9 and fall down towards the bottom of the drum. In this way, a spreading of the items of mail along the longitudinal direction of the drum 4 is achieved such that the items of mail that have a thickness that is less than the separation of the lamellae, i.e. 6 mm, will fall more easily through the openings and in this way be sorted out. The height of fall from the end of the glide arrangement 9 is considerably less than that from the end of the feed belt 1, which thus ensures that there is a lower risk of damage due to the lower height of fall of the items of mail.

The glide arrangement 9 is formed in the embodiments shown in the drawing by a plate, across the upper surface of which items of mail can glide. Figure 3 shows the approximate position, extent and orientation of the glide arrangement, that is, of the plate, relative to the feed belt 1 and the separation drum 4.

Figure 4 shows a plane view of the preferred embodiment of the glide arrangement 9 in the form of a plate. Dashed lines 10 are used to show a second possible design of the edges of the plate 9, such that it becomes more narrow towards its open end, the end situated furthest into the drum. When the edges become more narrow following the lines 10, some of the items of mail 2 that pass over the glide arrangement, the plate, 9, will fall down over the side edges, and in this way an even greater spreading of the items of mail 2 along the length of the drum 4 is obtained.

It is not necessary that the glide arrangement 9 should consist of a plate. It can be also have other designs, on the condition that it provides the same function, that is, leading the incoming items of mail inwards into the drum such that they obtain a component of velocity along the axial direction of the drum. A glide arrangement could, for example, consist of a smooth cloth that is placed under tension in a frame that extends into the drum.

As has been mentioned in the introduction, increasing the sorting capacity of the sorting arrangement described above has also been an aim of the invention. Increasing the rate of rotation of the drum from 14 revolutions per minute to approximately 18 revolutions per minute has previously been selected as a means of increasing the capacity. It has been shown to be possible to further increase the capacity of the drum by the arrangement of a glide arrangement according to the invention if the rate of revolution is instead reduced, while at the same time less damage of the items sorted with the aid of the separation drum is obtained. A reduction of the rate of rotation to approximately 5 revolutions per minute achieves, very surprisingly, an increase in capacity, and the speed of the feed belt 1 can be somewhat increased such that a greater number of items of mail per unit time can be sorted with the aid of the separation unit, since the rate of feed increases. It is clear that a greater probability for those items of mail that should be able to pass through the openings between the lamellae 6 in the drum 4 to actually pass through these openings is achieved through the lower rate of revolution and the increased spreading of the items of mail 2 along the length of the separation drum 4. At the same time, the risk of the items of mail 2 being carried along with the rotation of the drum, and being released when they have reached the upper part of the drum is reduced, and for this reason less damage occurs also due to the risk that the items of mail falling back in this manner will damage the items of mail onto which they fall or themselves. On the other hand, during previous attempts to reduce the rate of revolution of the drum items of mail have become congested at the input location from the feed belt 1, and it has been necessary to reduce also the speed of the feed belt in order not to completely fill the drum. The result has thus been a reduction in the sorting capacity of the drum.

It is obvious that the precise dimensions not only of the drum but also of the glide arrangement can be varied, as can the rate of rotation of the drum, from those that have been described above without deviating from the innovative concept of the invention.

Not only is the sorting capacity of the separation drum increased using the method and the arrangement according to the invention, but also the amount of mail that must be sorted out by hand before the automatic sorting is reduced, in that the items of mail are handled more carefully. The need for manual work at the coarse sorting belt is in this way reduced, and personnel costs can be reduced.

Claims

1. A method for a sorting means, in particular at a separation drum in a mail sorting facility, in which items of mail are fed with the aid of a feed belt (1) in through one end wall to a rotating separation drum (4), c h a r a c t e r i s e d in that incoming items of mail are given a velocity and thus a spreading along the axial direction of the drum (4) in that they are led from the feed belt (1) over a glide arrangement (9) arranged extending into the drum and tilted downwards from the feed belt (1) .

2. The method according to claim 1, c h a r a c t e r i s e d in that the glide arrangement (9) becomes narrower (10) in the direction passing into the drum (4) such that the items of mail (2) are allowed to fall over the side edges of the glide arrangement (9) .

3. The method according to claim 1 or 2, c h a r a c - t e r i s e d in that the drum rotates with a lower rate of revolution than that of an equivalent separation drum (4) that lacks the glide arrangement (9) .

4. The method according to claim 3, c h a r a c t e r i - s e d in that the speed of the feed belt (1) is higher than that of an equivalent feed transport for a separation drum that lacks the glide arrangement (9) .

5. An arrangement for a sorting means arrangement, in particular for a separation drum at a mail sorting facility, in which items of mail are fed with the aid of a feed belt (1) into one end wall of a rotating separation drum (4) , c h a r a c t e r i s e d in hat a glide arrangement (9) is arranged to lead incoming items of mail (2) from the feed belt (1) such that they are given a velocity and thus a spreading along the axial direction of the drum (4) .

6. The arrangement according to claim 5, c h a r a c t e r i s e d in that the glide arrangement (9) is arranged extending inwards from the feed belt (1) into the drum (4) and tilted downwards towards its bottom.

7. The arrangement according to claim 6, c h a r a c t e r i s e d in that the glide arrangement (9) is formed from a plate.

8. The arrangement according to claim 7, c h a r a c - t e r i s e d in that the plate becomes more narrow (10) in the direction inwards into the drum.