US3782541A

US3782541A - Apparatus for transferring stacks of mail or like articles

Info

Publication number: US3782541A
Application number: US00314241A
Authority: US
Inventors: D Wood
Original assignee: Masson Scott Thrissell Engineering Ltd
Current assignee: Masson Scott Thrissell Engineering Ltd
Priority date: 1971-12-15
Filing date: 1972-12-11
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: DE2261520A1; GB1374093A

Abstract

An automatic letter sorting machine including a large number of individual sorter boxes arranged in horizontal rows, a number of horizontal conveyors for delivering mail via deflector gates to the individual boxes, individual ejectors for ejecting stacks of mail from the boxes, a power operated receiver shelf moving vertically on guides at the front of the machine with compartments to receive the ejected mail, an overhead discharge conveyor at the top of the machine, a further ejector for shifting stacks of mail from the receiver shelf into compartments of the discharge conveyor, and an automatic mail bundling machine at the output of the discharge conveyor.

Description

APPARATUS FOR TRANSFERRING STACKS OF MAIL ()R LIKE ARTICLES [75] Inventor: David Wood, Clevedon, England [73] Assignee: Masson Scott Thrissell Engineering Limited, Bristol, England I [22] Filed: Dec. 11, 1972 [21] Appl. N0.: 314,241

[30] Foreign Application Priority Data Dec. 15, 1971 Great Britain 58,262/71 [52] US. Cl. ..209/74 R, 214/1 M, 2l4/8.5 F [51] Int. Cl. .L B65g 59/00 [58] Field of Search...., 209/73, 74 R; 271/64; 214/8.5 R, 8.5 F, 8.5 SS, 1 M, 11

[56] References Cited UNITED STATES PATENTS 3,429,239 2/1969 Murchison et al 271/64 X 3,459,300 8/1969 McGuire 209/73 3,573,748 4/1971 Holme 214/11 3,696,946 10/1972 Hunter 209/73 3,674,143 7/1972 Hunter 27l/64 Jan. 1, 1974 OTHER PUBLICATIONS IBM Technical Disclosure Bulletin, Vol. 13, No. 5 October 1970, Hillsley, R. H., et al.

Primary ExaminerAllen N. Knowles Att0rneylrvin S. Thompson et al.

[57] ABSTRACT An automatic letter sorting machine including a large number of individual sorter boxes arranged in horizontal rows, a number of horizontal conveyors for delivering mail via deflector gates to the individual boxes, individual ejectors for ejecting stacks of mail from the boxes, a power operated receiver shelf moving vertically on guides at the front of the. machine with c0mpartments to receive the ejected mail, an overhead discharge conveyor at the top of the machine, a further ejector for shifting stacks of mail from the receiver shelf into compartments of the discharge conveyor, and an automatic mail bundling machine at the output of the discharge conveyor.

8 Claims, 8 Drawing Figures PATENTEDJAN H I 3,782,541

SHEET 5 0F 5 APPARATUS FOR TRANSFERRING STACKS OF MAIL OR LIKE ARTICLES This invention relates to apparatus for unloading conveying, and/or transferring stacks, or individual items, of mail or like flat articles, from a plurality of separate boxes or magazines, and the invention is particularly though not exclusively applicable to apparatus for unloading and transferring mail from automatic letter sorting machines.

Conventional letter sorting machines are provided with a large number of individual destination sorter boxes, normally arranged in horizontal rows and vertical columns. The boxes are closely spaced in both directions and in view of the large number of boxes, and various operating criteria, difficulties are experienced in providing for automatic unloading and transfer of pre-sorted stacks of mail collected in the boxes. Obviously the individual stacks should not be disorganized after sorting, and it is also important that the equipment should be relatively simple and economical to produce without excessive duplication of parts. Also in some special applications the unloading and transfer equipment should be capable of operating in accordance with different programmes of unloading, for example to clear individual boxes, or rows of boxes, or alternatively to clear the complete machine at the end of a working shift.

Accordingly it is an object of the invention to provide an improved apparatus for transferring stacks of mail or like articles from equipment such as a sorting machine, which will overcome or alleviate some of the existing problems and disadvantages and which will satisfy as far as possible the requirements stated above, while in some cases also providing further optional features and advantages which will become apparent below.

Broadly stated the invention consists in apparatus for transferring stacks of mail, or like flat articles, from a sorting machine having a plurality of sorter boxes or guides arranged in several rows, comprising an extended travelling receiver, spanning across several or all of the boxes in a row, means for moving the receiver in a direction perpendicular to the lengths of the rows, and means for discharging stacks of articles from the receiver.

According to a preferred feature of the invention the receiver extends horizontally and is movable vertically, and preferably it is arranged to discharge the stacks of mail at an elevated level which may be above or adjacent the top of the sorting machine. At this elevated level for instance there may be a discharge conveyor which extends parallel withthe receiver and passes overhead to an adjacent associated machine such as an automatic bundling machine arranged to tie each of the individual stacks.

The transfer apparatus is preferably arranged to be mounted entirely externally of the sorting machine adjacent the discharge openings from the individual sorter boxes. This has a number of advantages. It enables the transfer apparatus to be provided as an additional item, to an existing standard machine, which may alternatively be used with manual unloading facilities. Also this system enables the apparatus to be so designed that the mail is visible at all times and access is readily available in case of any stoppage.

In a particular convenient construction the receiver is in the form of an extended horizontal shelf unit supported to move vertically on vertical guides attached to the main sorting machine. The movements of the shelf are preferably controlled automatically by a control unit having inputs from sensors arranged to detect when any or all of the individual sorter boxes require to be unloaded.

The shelf unit is conveniently formed with a number of parallel slots or spaces extending both below each stack and also vertically upwards on the outer edge of each stack. This facilitates ejection of the stacks from the receiver. The receiver is also preferably formed with partitions or spacers at intervals corresponding to the spacing between the individual boxes in a row.

The means for ejecting stacks from the receiver are preferably arranged to'transfer the stacks individually in a generally horizontal direction perpendicular to the length of the receiver and this ejector mechanism may be arranged to eject individual stacks, or in groups, or all stacks simultaneously.

The discharge conveyor is also preferably provided with spaced partition elements at intervals corresponding to those of the individual sorter boxes in a row so that the stacks can be transferred ontothis conveyor directly from the receiver.

According to another preferred feature of the invention the apparatus includes means for sensing the presence of stacks of mail in individual compartments or locations of the receiver. The signals from these sensing means may be collated with those from other detector or sensor means for detecting which of the sorter boxes require to be unloaded, and also with signals from means for detecting the presence or absence of mail in any of the positions or locations of the discharge conveyor. In this way it is possible to avoid unnecessary movements or excursions of the receiver. For example the receiver may in one excursion collect stacks of mail from a number of different rows, provided that the particular sorter boxes to be discharged at any row are aligned with unoccupied compartments of the receiver. Likewise stacks of mail from compartments of the receiver can be discharged onto the output conveyor provided that the respective compartments of the conveyor are unoccupied. Conveniently these detectors or sensors include optical projection systems combined with photosensitive devices, which are particularly convenient for detecting the presence or absence of mail, and can readily detect even one article.

The invention may be performed in various ways and one specific embodiment will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic front elevation of an automatic letter sorting machine with mail transfer apparatus according to the invention combined therewith.

FIG. 2 is a diagrammatic partly sectional end elevation of the sorting machine with the transfer apparatus,

FIG. 3 is a diagrammatic end elevation on an enlarged scale of one of the mail ejector devices for an individual sorter box,

FIG. 4 is a plan view of the travelling shelf or receiver,

FIG. 5 is a fragmentary perspective view of part of the travelling receiver,

FIG. 6 is a detailed sectional plan view on an enlarged scale illustrating the rollers on the receiver engaging one of the vertical guide rails,

FIG. 7 is a fragmentary front elevation on an enlarged scale, illustrating part of the shelf-ejector mechanism at the top of the apparatus for ejecting stacks of sorted mail from the travelling shelf, and

FIG. 8 is a simplified diagram illustrating the main automatic control features of the apparatus.

Referring first to FIGS. 1 and 2 the basic sorting machine may be as described in my copending application Ser. No. 303,941, filed Nov. 6, 1972.

The sorting machine is built-up from a series of box modules, in this example an input module 9 and two sorter box modules indicated generally at 10 and 11, each comprising four horizontal rows of destination sorter boxes 12. Above each row of boxes is arranged a horizontal transporter orconveyor 13 of the type described in my copending application Ser. No. 303,941, filed Nov. 6, 1972. These conveyors l3 carry the envelopes, each in a horizontal attitude, horizontally across the tops of the individual sorter boxes 12, with deflector gates 14 positioned one above each box for directing particular selected envelopes into selected boxes. The conveyor 13 of each box module is arranged closely adjacent to and aligned with the corresponding conveyor in the next box module so that mail is automatically transferred from one box module to the next, and thus can traverse the length of the machine regardless of the number of modules that may be included.

Incoming unsorted mail is delivered along an input conveyor 15 which includes a creep feed belt controlled by a photo-cell device at the delivery end of the conveyor. From this conveyor the individual envelopes, which have previously been marked with a coded destination symbol, are fed through an automatic code reader 16 of known design which controls electronic logic circuitry arranged to actuate the deflector gates 14 at the correct instants. The mail is conveyed from this code reader 16 to a vertical elevator section 19 provided with four lever deflector gates 18 for directing the envelopes as required onto any one of the four horizontal levels, after which the mail is moved horizontally and directed into the appropriate sorter box 12 by the conveyors l3 and deflectors 14 as described above.

The equipment also includes an automatic bundling machine 20 positioned adjacent to but spaced from the sorting machine, and an overhead output conveyor 21 at the top of the sorting machine is arranged to carry the sorted bundles of mail to the bundling machine, thus minimising the floor area occupied by the machine; this overhead system also having valuable advantages in conjunction with the receiver unit which will be described in more detail below.

The individual stacks of sorted mail in the sorter boxes 12 are ejected horizontally towards the front of the machine by an ejector system as illustrated diagrammatically in FIG. 3 and described in more detail in copending application Ser. No. 309,987, filed Nov. 28, I972.

The apparatus illustrated in FIG. 3 comprises one of the vertical sorter boxes or magazines 12, having front and

rear walls

31, 32, and side walls 33. A vertically movable platform 34 is arranged to support a stack of mail 35 and is slidably mounted on a pair of vertical guide rods 36. The platform consists of a pair of parsllel spaced plates each attached to a block 38 sliding on one of the guide rods 36. The platform is urged upwardly by a pair of springs 40 connected to the blocks 38 and to fixed points on the framework of the apparatus. The spring rate is selected to correspond to the weight/height relationship (i.e. density) of average mixed postal mail within the territory in which the sorting machine is operating. In this way the level of the top letter or envelope in the stack 35 is maintained approximately constant as the height of the stack increases, and somewhat above the level of the bottom edge of the front wall 31 which acts to retain the top part of the stack within the magazine.

The stack of mail on the platform 34 is ejected by a generally vertical pusher plate 45 attached to a-block 46 which is slidably mounted on a horizontal guide rod 47. Normally the pusher plate 45 is positioned on the extreme left side of the stack as illustrated in FIG. 3 but when traversed to the right the greater part of the stack of mail on the platform 34 is ejected into a travelling receiver 50. Any mail in excess of the predetermined height of the stack is retained by the front wall 31. This excess mail is supported temporarily by a rigid polished metal horizontal plate 51 attached to the upper end of the pusher plate 45.

The movements of the platform 34 and the pusher plate 45 are controlled by a flexible tension cord 53 wound onto a bobbin 54 which includes a coiled tensioning spring (not shown) and an electrically controlled clutch for coupling the bobbin when required to a rotary drive shaft 55 driven continuously by a main electric motor of the sorting machine and extending along each row of such destination sorter boxes. The tension cord 53 extends around a guide pulley 56 and has a bight 57 extending vertically upwards around a pulley 58 attached to the movable guide block 38. The other end of the bight passes around another stationary pulley 59 and extends horizontally around a further pulley 60 positioned at the front of the machine, the other end of the tension cord 53 being attached to the guide block 46 at the bottom edge of the pusher plate 45. A light tensator type return spring 61 attached to a cord 62 is provided to return the pusher plate 45 to the left hand position when the bobbin clutch 54 is deenergized.

The apparatus also includes locking rollers 63 attached to the underside of the platform 34 and bearing against the face of the pusher plate 45 to prevent the pusher plate moving to the right to eject a stack until the platform 34 has descended to its bottom position and the rollers are clear of the plate. Further locking rollers 64 are also provided to prevent the platform 34 rising until the pusher plate 45 has moved to its extreme right-hand eject position. These rollers 64 are attached to the rear of the pusher plate 45 near its lower end, and when the platform 34 is fully depressed the rollers can bear down on the top surface of the platform. In addition the apparatus includes a switch SW1 arranged to close when the platform 34 has moved downwards to the position indicated at 34 corresponding to a full magazine, and another switch SW2 arranged to open when the pusher plate 45 has moved to its extreme right-hand eject position.

The load resistance applied by the springs 40 of the platform 34 on the tension cord 53 is considerably greater than the resistance encountered by the pusher plate 45, in normal operation, so that when tension is applied to the cord 53 by the clutched bobbin 54 and cord will tend first to pull the pusher plate 45 across to the right. This being prevented by the interlock rollers 63 the cord will first pull down the platform, and only when the platform reaches its bottom position as indicated at 3d, and the interlock rollers 63 are freed, will the tension cord tend to move the pusher plate 45 to the right.

In normal operation the platform 34 descends progressively under the increasing weight of mail until when the platform has reached its selected bottom position, signifying a full box, switch SW1 closes which operates a control circuit, and the clutch is energised. With the platform 34 in its bottom position 34' the pusher plate 45 is free to move to the right and the engaged clutch winds in the cord 53 onto the bobbin and so pulls the pusher plate 45 to the right to eject the stack of mail l5. During this movement the locking rollers s4 prevent the platform ascending. When the pusher plate reaches itsextreme right hand position switch SW2 opens and causes the clutch to disengage. With the locking rollers 64 clear of the platform the latter is then free to rise under the influence of the tension springs AM so unwinding the tension cord 53 from the bobbin 5 When the platform reaches its uppermost position the pusher plate 45 is automatically drawn back to the left hand position by the tensator 61, thus unwinding further cord from the bobbin. The cycle can i then repeat.

chine Z ll includes a travelling shelf unit 70 which extends across the full horizontal width of the front of the machine and delivers the stacks of mail onto the output conveyor it. The shelf unit 70 is carried by a bracket 71 having pairs of rollers 72 which engage the front and rear edges of a pair of parallel

vertical guides

74, 75 se cured to the front face of each box module. The receiver shelf is raised and lowered along the vertical guides by a motor 75 (see FlG. 2) operating through an endless tension cord 76, and controlled by the aforesaid logic circuit control unit, in conjunction with trip switches 77 positioned at each individual horizontal level. The receiver shelf can thus be directed to any selected horizontal row of sorter boxes. As illustrated in FIGS. 4 and 5 the shelf unit comprises a number of separate L-shaped bracket elements 78 each provided with a vertical partition wall 79 and rigidly secured to a horizontal bar hill attachedto the bracket 71. The individual compartments so formed are spaced at the same horizontal intervals as the sorter boxes 12 so that mail ejected from the sorter boxes will enter the appropriate compartments in the direction of the arrows 81 in FIG. 4, without further transfer apparatus. Each compartment of the receiver has a slot 82 in its bottom wall and a corresponding slot 83 in its front wall, thus facilitating subsequent ejection of the stacks onto the output conveyor Ill. This also permits hand access when necessary to any one of the sorter boxes in the case of a stoppage,

even though the receiver shelf may be in position at that level. Furthermore each of the compartments in the receiver shelf is provided with an optical reflex sensor 84 (see FIG. 5) in the form of a small lamp located on the bar hit in each slot 82 and positioned closely adjacent to a photocell arranged to provide an output signal depending upon whether or not light is reflected onto the photocell by an item of mail in the compartment.

When the receiver shelf unit is in its topmost position as illustrated in dashed lines at 70 in FIG. 2 it cooperates with an automatic ejector system (see FIGS. 2 and 7) comprising a number of spaced vertical arms spaced horizontally apart at intervals corresponding to the gaps 82 in the receiver shelf, and attached to a number of transverse endless actuator belts or chains 91 driven by sprockets on a shaft @ti, controlled by a reversible motor 9'7. The arms 90 are carried by a transverse bar 92 carried by guides 93 on horizontal guide rails 9%. When the belts 91 are actuated the arms 90 are moved to the left in FlG. 2 thus carrying all, or any, stacks of mail on the shelf 70 horizontally across onto the output conveyor 21.

The output conveyor 21 comprises an endless belt or chain conveyor 104 having a number of hinged compartment elements 103 at spaced intervals along the chain, corresponding to the dimensions of the sorter boxes 12 and the compartments of the receiver shelf 70.. For convenience and to reduce the overall height of the apparatus these hinged elements 103 automatically fold flat against the chain when returning along the bottom run as illustrated at 105. The conveyor 104 is driven by a motor 106, and located on the back wall 107 of the conveyor structure, at positions aligned with the sorter boxes 12, are a series of reflex optical sensors 108 similar to the sensors 84 previously described. These sensors lltlfi indicate the presence or absence of mail in the compartments of the output conveyor 21.

At the moment of transfer of the mail from the re ceiver shelf unit 70 onto the output conveyor 21 the movement of the output conveyor M is automatically halted, and the sensors 108 provide individual output signals for detecting the presence or absence of mail in each of the compartments of the output conveyor. The output signals from these individual sensors are combined in the logic circuitry llld of the control unit (see FIG. 8) with the corresponding signals from the sensors 84 on the receiver shelf 70., and the

ejector mechanism

90,91 is only permitted to transfer mail if all the appropriate spaces or compartments of the output conveyor are'unoccupied. If any essential compartment is occupied the conveyor 21 will automatically advance, under the control of the unit 110 and motor 1% until vacant compartments are detected, at which stage the

mechanism

90,91 will be automatically actuated.

Unless interrupted or checked for any reason the output conveyor 21 will operate continuously to deliver the stacks of mail to the automatic bundling machine 20. This machine may be of any known type, of which many existing designs are well known, and since the particular details of the bundling, machine form no part of the present invention it will not be further described herein.

FIG. 8 illustrates in simplified from the main automatic control functions of the apparatus. The control unit 110 has multiple inputs, shown here for convenience as four only, ill-114.. Input 111 is connected to the sensors 84 in the compartments of the travelling shelf 70: input 112 is connected to the sensors 108 located opposite the compartments of the top conveyor 21: input 113 is connected to sensors (such as switches SW1) for detecting when the sorter boxes 12 are full (or nearly full); and input 114 is connected to the level trip switches 77 for controlling the position at which the shelf unit 70 is halted. The control unit has outputs to the

motors

75, 97 and 106 controlling respectively the movements of the travelling shelf unit 70, the

ejector mechanism

90,91 and the top conveyor 21.

The logic circuitry in the control unit 110 referred to above may conveniently be included, or form an integral part of the logic circuitry of a computer in the sorting machine used for code translation purposes, for deciphering coded addresses on. individual envelopes, and for providing memory functions to control and record the passage of individual envelopes or stacks of mail through the machine.

The machine described has a number of important advantages. it will be noted that the emptying of the sorter boxes 12 and the transfer of sorted packs of mail is carried out entirely automatically (unless manual over-rides are used) while the main sorting section of the machine is in operation. This results partly from the design of the ejector systems as illustrated in FIG. 3, which allows mail to be delivered continuously into each sorter box even when an eject operation is in process. This facility is afforded by various features including the horizontal plate attached to the top of the pusher plate 51, so that further incoming mail is supported while the eject operation is carried out.

It will also be noted that the machine is entirely of modular construction so that any required numer of sorter box modules 10,11 can be combined with the input module 9 and the bundling machine 20. Each of the horizontal rows of sorter boxes 12 in each box module is also capable of being replaced by an alternative row of boxes of different dimensions. Furthermore the transfer mechanism including the output conveyor 21 leading to the bundling machine can be readily fitted to an existing sorting machine with manual unloading facilities. The mail is clearly visible and accessible at all times at all parts of the machine which is of considerable advantage in clearing any stoppage. The transfer equipment includes only one receiver shelf unit to clear stacks-of mail from all the sorter boxes, a considerable economy in cost over any other system using multiple conveyors. The machine can also readily handle sorting programme changes which require that the whole of one horizontal row of boxes should be emptied at an arbitrary time before a new sorting programme can be commenced. The individual sensors fitted to the sorting boxes, receiver shelf compartments, and output conveyor compartments, enable the machine to operate at maximum capacity with minimum movements of the receiver shelf 70.

I claim:

1. Apparatus for transferring stacks of flat articles, for example mail envelopes, from a sorting machine having a plurality of sorter boxes arranged in several parallel rows, comprising a travelling receiver of extended length, spanning across a plurality of sorter boxes in a row, means for moving said receiver in a direction perpendicular to the lengths of said rows, means for discharging stacks of articles from said sorter boxes onto said receiver, and means for discharging stacks of articles from the receiver.

2. Apparatus according to claim 1, in which said sorter box rows and said receiver extend horizontally, and said receiver is movable vertically.

3. Apparatus according to claim 1 in which said receiver is provided with compartments spaced at intervals corresponding to the spacing of said sorter boxes.

4. Apparatus according to claim 3, including means for sensing the presence of articles in the said individual compartments of the receiver.

5. Apparatus according to claim 1, including an output conveyor extending parallel with said receiver, said output conveyor having spaced receptacles at intervals corresponding to the spacing of said sorter boxes.

6. Apparatus according to claim 1, in which said receiver is located on guides, and positioned externally of said sorting machine. 7

7. Apparatus according to claim 1, including individual ejector means for ejecting stacks from said sorter boxes, and control means for controlling such ejection in accordance with the sensed capacity of said receiver to accept such stacks.

8. Apparatus according to claim 1, and wherein said receiver is provided with compartments spaced at intervals corresponding to the spacing of said sorter boxes, and including means for sensing the presence of articles in the said individual compartments of the receiver, an output conveyor extending parallel with said receiver, said output conveyor having spaced receptacles at intervals corresponding to the spacing of said sorter boxes, individual ejector means for ejecting stacks from said sorter boxes onto said receiver, sensing means responsive to the size of each stack in the individual sorter boxes, and control means for controlling the movements of said receiver in response to signals from said sorter box sensing means, and for controlling said individual sorter box ejector means in response to the sensed position of said receiver.

Claims

6. Apparatus according to claim 1, in which said receiver is located on guides, and positioned externally of said sorting machine.