GB2331973A

GB2331973A - Brake for a conveyor unit

Info

Publication number: GB2331973A
Application number: GB9722110A
Authority: GB
Inventors: Paul Whittles; Jonathan Warrilow
Original assignee: Dexion Group Ltd
Current assignee: Cork Oak Holding Ltd
Priority date: 1997-10-20
Filing date: 1997-10-20
Publication date: 1999-06-09
Also published as: GB9722110D0; AU9548198A; EP1025028A1; WO1999020550A1

Abstract

A brake for use in a conveyor unit where the conveyor unit 21 comprises a plurality of rollers 22 forming a load bearing surface, driven by a belt 23, and displaceable in a plane perpendicular to the load bearing surface. The brake is in the form of a plate 33, actuatable to displace the rollers such that the belt no longer imparts a driving force to the rollers, hence providing a braking force. Air cylinders 34 may be provided to actuate the brake plate, and the brake plate may be controlled by means of a control system. Other conveyor units disclosed may also comprise a plurality of rollers driven by a belt. One of these may have rollers mounted in slots in a frame, and another may have tapered rollers adapted to form a curved section of a conveyor track (see fig 4a). Also disclosed is a conveyor system that may comprise a plurality of conveyor units, controlled by a control system. The control system may have a main control device and control means on at least some of the conveyor units that control the operation of the conveyor unit or units in a predetermined sequence determined by the main control device, the sequence operating until fresh signals are sent from the main control device.

Description

1 Conveyor Sy 2331973 This invention relates to a conveyor system and to a

control system for such a system.

Conveyor systems having a plurality of paths for objects being conveyed by the system are known particularly, but not exclusively, in warehouse systems for the transportation, sorting, storage and delivery of loads and other packaged items. Such conveyor systems typically utilise roller conveyors and/or belt conveyors and a variety of controllable sorting/merging elements for directing particular packages along a desired path to a desired destination.

This necessitates the use of units designed to enable the packages being transported, for example, to be diverted on to other tracks, to be weighed, and to have labels such as addresses and postage franking, automatically placed on the load in accordance with predetermined requirements. In general terms, such elements as diverters and sorters are well known. Typically, such large scale systems are designed and built on an individual basis depending on the design requirements. Control of such systems is typically achieved from a central computerised location to which each operating part of the conveyor system is connected to enable control signals to be sent to that part. Power to drive electric motors etc. is also achieved by wiring the whole conveyor system on an individual, bespoke manner. Such systems have two prime disadvantages. Firstly, since they are designed for a single installation on a one-off basis, the design, manufacture assembly and installation costs are high and not easily predictable. Particularly, a skilled workforce is required to install and set up the system and its control circuitry, which requires the use of skills in several disciplines. Such systems also lack flexibility if subsequent changes are required to the functioning andlor layout of the system.

Furthermore, the use of a centralised computerised control system has practical limits in the amount of signals which can be given to each unit and the more units there are and the more signals that are required to be processed, the slower the control system can function.

In a typical installation, each unit where options for the functioning of the unit are possible, has detector means to detect the presence or absence of a package and frequently 1 2 to send a signal to the central control identifying the package. The central computer then has to work out what should happen to the package and should then send the appropriate signals to the controls on the unit concerned. Testing out all these aspects of a bespoke system which has been designed and built as a one-off is very expensive. It is also necessary to spend a great deal of time and effort on commissioning and testing all aspects of the system.

The present invention seeks to provide a conveyor system which alleviates the problems of the known apparatus.

According to the present invention there is provided a conveyor system comprising a plurality of modular conveyor units, adapted to be assembled together in a desired layout, and a control system for controlling the operation of the conveyor units, the control system having a main control device and control means on at least some of the conveyor units, each control means being adapted to control the operation of its associated conveyor unit in a predetermined sequence determined by the main input, the sequence operating as predetermined until fresh control signals are sent from the main control device.

Preferably, at least some of the conveyor units include power means adapted to control the functioning of that unit in accordance with control signals from the control means on the unit. Preferably, the control means of each unit includes cabling such as electrical or optical cables and, optionally, a power cable to power the power means, the cabling of adjacent conveyor units being adapted to be connected together, preferably by standardised plug couplings.

In this way, the conveyor system according to the present invention provides a plurality of standardised conveyor units which may be easily assembled into a required configuration by using the necessary selection from a plurality of standardised units.

Preferred embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:Figure 1 shows, in block diagram form, the layout of a known system, Figure 2 shows a schematic diagram of a control system in accordance with the present invention, Figure 3A shows a side view of a straight roller conveyor section driven by an electric motor, i 3 Figure 3B shows schematically, a braking arrangement for incorporation in the unit of Figure 3A, Figure 4A shows a powered curved conveyor unit, Figure 4B shows a cross-section through the unit shown in Figure 4A, Figure 4C shows a detail of the drive arrangement of the embodiment of Figure 4A, Figures 5A to 511 show a selection of modular conveyor units and, Figures 6A to 61 show further examples of modular conveyor units.

Referring now to Figure 1, there is shown, in schematic form, a known type of control arrangement for a conveyor system. The system has a centralised management control 1, which supplies control signals to a centralised control computer 2, known as a router, a hub 3 connected to the router 2 and a plurality of control means 4 connected to the hub each designed to control a particular part of the conveyor system. The "em has three further stations connected to the router 2, namely a label printing station 5, a weighing station 6 and a user interface station 7, which may be, for example, a dispatch station. Each of these stations has associated with it a bar code reader, respectively Y, 6' and 7' designed to detect the presence of and identify a package in the appropriate station. This information is sent to the router which then computes the appropriate signal for the stations 5, 6 and 7 andlor, receives information from these stations which is used to calculate, for example, the type of label to be placed on the package, postage rates for franking and destination.

It can be seen that this known system requires the central computer in the router 2 to perform a large number of calculations. The more calculations that the router has to make, the slower it operates, which is a disadvantage of the known system.

Turning now to Figure 2, there is shown in schematic form, the concept of the present invention. As in the known arrangement, the system has a main control input 11 and a main computer 12. The computer 12 is connected to a bus 13.

The control system is intended to control the operation of a conveyor system consisting of a plurality of individual modular units. Each unit has its own control means 14 to 20 comprising a programmable embedded electronic controller connected to the bus 13. The control means on each modular unit also includes a bar code reader (BCR) which is designed to read a bar code on packages passing along the modular unit. This signal is 4 sent to the embedded electronic controller which is pre-programmed by the main computer 2 to initiate the appropriate functioning for the unit. For example, in the embedded electronic controller 16 the package at a weighing station in the associated conveyor unit has its weight determined. This information in conjunction with the information derived from the bar code reader is processed by the embedded electronic controller 16 to, for example, send all packages below a certain weight along a first path and packages above that weight along a second path utilising, for example, a diverter to do so. Examples of such diverters are described hereinafter. This predetermined functioning of the conveyor unit containing the embedded electronic controller 16 remains unchanged until the embedded electronic controller is reprogrammed by control signals from the main computer 12.

In this way, the operation of the conveyor unit controlled by the embedded electronic controller 16 is controlled on the unit itself so that there is no need for control signals to be sent to and from the main computer 12. In this way, the functioning of the computer 12 is not slowed down or impaired in any way and the conveyor unit is controlled much more quickly and accurately, without the possibility of interference, by the localised control exerted by the embedded electronic controller.

Although described as utilising bar code readers to detect and identify packages, it will be appreciated that in certain circumstances the mere presence of a package may be all the control information required, in which case a simple presence detector would provide the input to the embedded electronic controller.

Turning now to Figure 3A, there is shown a sectional side view of a conveyor unit 21 consisting of a plurality of rollers 22 driven via a belt 23 by an electric motor 24. The operation of the drive motor 24 is controlled by a control device on the unit incorporating a embedded electronic controller. The electric motor 24 drives a belt drive wheel 25, the drive belt 23 being guided by guide rollers 26 so that it passes round at least half the circumference of the drive wheel 25. The drive belt 23 is an endless belt and extends over the length of the conveyor unit, being supported by idler rollers 27 spaced at intervals along its length below the bottom run of the belt and idler rollers 28 which support the top run of the belt in a predetermined plane. The rollers 22 are provided at their two ends with through axles 22A by which the rollers 22 are freely rotatably mounted in the frame i of the conveyor unit. The through axles rest in slots open at their top edge so that the conveyor rollers 22 can simply be dropped into the slots as appropriate. The rollers 22 rest on the top run of the drive belt 23 with their stub axles clear of the bottom of the slots in which they are located. This arrangement not only has the advantage of rapid assembly of the conveyor but also if a foreign body falls between the rollers 22 and the drive belt 23, the rollers 22 are just lifted up in the slots. In this way, the risk of damage to the conveyor unit or the drive mechanism by such foreign bodies is substantially reduced. The drive force on the rollers 22 on the belt 23 is derived simply from the weight of the rollers 22. When a load is resting on the rollers 22, they are urged with a much greater force onto the drive belt 23 to enable a sufficiently powerful driving force.to be transmitted to the rollers 22 as the frictional d riving force is, to a large extent, weight-dependent. This has the further advantage that when a load is not being driven by the rollers 22 only a very low stress is applied to the drive belt 23 as this is generated solely by the weight of the roller 22. Figure 3B shows a braking arrangement which is incorporated in the conveyor unit illustrated in Figure 3A. Four brake units 29, 30, 31 and 32 are illustrated. As the brakes are identical, only one will be described. The brakes extend along the length of the conveyor unit and are each designed to brake approximately a quarter of the length of the conveyor unit, selectively, in dependence upon detection apparatus (not shown), which detects the presence or absence of a load in the section of conveyor controlled by the respective braking unit.

The brakes 29 to 32 each consist of a flat brake plate 33, which, when the brakes are not operable, lies adjacent the drive belt 23 immediately below the lowermost part of the rollers 22.

The braking plate 33 is raised by two pneumatic air cylinders 34 to lift the rollers 22 clear of the drive belt 23. In this way the rollers 22 are brought to a standstill together with any load resting on them. The control system of the conveyor unit 21 includes sensors to detect the presence or absence of a load in each of the four zones determined by the braking units 29 to 32. Thus, if a load is detected in the zone controlled by the unit 29, the brake 30 is operated to stop the rollers in its zone to stop a load in this zone hitting the load in the zone 29. Although, as shown, the braking surfaces are lifted into the braking position by pneumatic cylinders, it will be understood that other forms of lifting 6 the brakes may be used. The control system of the braking is, again, controlled locally on the individual conveyor unit.

Turning now to Figures 4A, 4B and 4C, there is shown a curved track section of roller conveyor on a module 35, the rollers being driven by an electric motor 36. The conveyor unit 35 is a self-contained module which includes its own electric motor and control circuit in a similar way to the straight section of roller conveyor described with reference to Figure 3. The unit 35 consists of a plurality of taper rollers 38 which are rotatably mounted in side frames 37A and 37B. The rollers 38 are driven by the electric motor 36 through a drive belt 39, shown more clearly in Figure 4C. The electric motor 36 powers a drive pulley 40 around which the drive belt 39 is guided by two guide wheels 41 and 42 so that the drive belt extends over more than 180' of the circumference of the drive wheel 40. At the ends of the conveyor unit, the drive belt passes round idler wheels 43 and 44. In order to maintain the arcuate path of the drive belt 39, which is of circular cross-section, and to ensure that the drive belt is in firm driving engagement which the taper rollers 38, the drive belt is guided and supported by a plurality of pressure rollers 45, shown in Figures 4B and 4C in addition to Figure 4A. The drive belt supporting surface on the pressure rollers 45 is substantially arcuate, the surface of the arc being substantially radial at the outermost part of the surface and extending axially at the innermost part of the arc. In this way, the pressure rollers accommodate the curve of the belt around the curve of the side frame 37A. The arc also serves to bias the drive belt 39 into driving contact with the taper rollers 38. Figures SA to 5H and 6A to 61 show different configurations of conveyor unit which may be incorporated in a conveyor system of the present invention. Figures 5A to 5D show four different sorts of straight conveyor section. Figure 5E shows a spur drive in which conveyor sections at approximately 300 to the axis of a straight section of conveyor are provided to enable items to be fed on to the straight section. Figure SF shows a form of diverter known as a plough merge. In this arrangement, two parallel belts 46 and 47 each carry loads and these are then merged into one row 48. The movement of the loads into the single line is controlled by gates 49 in accordance with control signals derived from the control embedded electronic controller on the conveyor unit itself. Figure 5G shows a gate 50 with sensors 51 which are again designed to control the operation of the gate utilising control signals generated on a purely 1 7 local basis.

Figure 511 shows a lane cross-over unit in which loads are transported from three parallel input belts 52 on to appropriate ones of three output belts 53 by control means which are controlled by control means located on the module itself.

Figures 6A to 61 show further designs of module. Figures 6A and 6C show straightforward straight sections of belt conveyor. Figures 613 shows a powered curved section. Figure 6E shows an arrangement in which a 90 transfer, in either direction, is possible. Again, this unit incorporates the necessary sensors and local control to detect the presence of a load and to determine its intended destination. The drive direction of the transfer unit is then determinedlocally by the control system on the unit itself. Figure 6F shows a module comprising a diverter unit to divert loads from a longitudinal path off at 30' to one or both sides of tlie straight section of conveyor, in accordance with locally generated control signals. Figure 6G shows a similar arrangement to that illustrated in Figure 6E. Figure 611 shows an arrangement similar to Figure 6F but incorporating a bar code reader. Figure 61 shows a module comprising a picking lane transfer. In this module, loads entering from a conveyor section 55 are detected and identified by a bar code reader 56 and in accordance with this data, the local control system moves the load to a selected one of two output conveyors 56 and 57.

It is envisaged, that the control and power wiring and cabling on each module will be designed to be incorporated as an integral part of the module and will terminate in standardised plug couplings. In this way, a conveyor system can be assembled by selecting appropriate modules from a catalogue so that the modules, in effect, constitute building blocks to enable the complete system to be assembled in any desired configuration.

This system has great advantages since each individual module will be able to be built, and tested, in the suppliers' factory before being transported to site for assembly. Once on site, the individual modules can be readily positioned, secured and connected to adjacent modules with the wiring simply being plugged together. The main computer could then be simply plugged in at an appropriate part of the system. Thus, assembly and set-up on site are greatly speeded up and simplified and do not need such skilled labour. Minor imperfections of the premises, such as floor levels, in which the system is to be installed, are easily accommodated by the flexibility provided by a number of relatively 8 small units being connected together on site.

In contrast, in the traditional bespoke systems long lengths of conveyor are constructed on-site and any minor undulations in the floor surface of the premises can cause difficulties in maintaining the correct alignment of the roller conveyor surface and frequently necessitate very time consuming packing of supports and realignment of the whole conveyor section.

The module concept of the present invention greatly facilitates the subsequent rearrangement of the conveyor system if requirements should change. The use of the local control system on each unit using programmable logic controllers also greatly speeds the functioning of the apparatus. For a given type of conveying, sorting and merging operation, once each individual module has been set up with its requirements from the main computer all control signals are generated and acted upon locally within that module so that the main computer is not overloaded and slowed down by having to process many control signals. If the requirements of the conveyor system are changed, for example, by changing destinations of the load or changes in the weight requirement labelling etc., it is merely necessary for the individual embedded electronic controllers to be reprogrammed from the main computer on an individual basis. Thus, only those requiring change are processed. This leads to greatly increased speed of control and adaptability for the whole apparatus.

It would be appreciated that many modifications may be made to the apparatus without departing from the overall concept of the invention of using a modular system in which each module which is adjustable has its own localised control circuitry which, once set in accordance with requirements, does not need control signals from the main computer.

1 1 9

Claims

Claims

1. A brake for use in a conveyor system, wherein the conveyor unit comprises a plurality of rollers forming a load bearing surface, which rollers are driven via a belt wherein the rollers are displaceable in a plane perpendicular to the load bearing surface and in that a braking plate is provided, which braking plate is actuatable to displace the rollers such that the belt no longer imparts a driving force to the rollers, thereby providing a braking force.

2. A brake according to Claim 1, wherein a surface of the braking plate (23) adapted to engage the rollers is provided with a friction material, so that the braking force applied to the rollers is load-dependent.

3. A brake according to Claim 1 or Claim 2, wherein the braking plate (33) is actuated by means of one or more pneumatic air cylinders.

4. A brake according to any one of Claims 1 to 3, wherein the actuation of the brake is controllable by means of a control system associated with each conveyor unit of a modular conveyor system.

5. A conveyor unit for use in a conveyor system comprising a plurality of rollers forming a load bearing surface driven by a drive belt, wherein the rollers are mounted in slots in a frame of the conveyor unit such that the rollers are displaceable in a direction perpendicular to the load bearing surface, wherein in the driving position the rollers rest on the drive belt, said drive belt imparting the driving force to rotate said rollers.

6.

top edge.

7.

A conveyor unit according to Claim 5, wherein the slots are open at their A conveyor unit according to Claim 5 or Claim 6, wherein in the unloaded position the rollers rest on the drive belt clear of the bottom of the slot, so that the ffictional driving force imparted by the belt to the rollers is at least in part load dependent.

8. A conveyor system comprising a plurality of modular conveyor units, adapted to be assembled together in a desired layout, and a control system for controlling the operation of the conveyor units, wherein the control system has a main control device and control means on at least some of the conveyor units, each control means being adapted to control the operation of its associated conveyor unit or units in a predetermined sequence determined by the main control device, the sequence operating as predetermined until fresh control signals are sent from the main control device.

9. A conveyor system according to Claim 8, wherein at least some of the conveyor units include power means adapted to control the functioning of that unit in accordance with control signals from the respective control means.

10. A conveyor system according to Claim 8 or Claim 9, wherein the control means of each unit includes cabling such as electrical or optical cables, the cabling of adjacent conveyor units being adapted to be connected together, A conveyor system according to Claim 10, wherein adjacent conveyor units are connectable together by standardised plug couplings.

12. A conveyor system according to Claim 10 or Claim 11, wherein the cabling includes a power cable to power the power means.

0. A conveyor unit for use in a conveyor system according to Claims 8 to 12, comprising a plurality of rollers forming a load bearing surface driven by a drive belt, wherein the rollers are taper rollers adapted to form a curved section of conveyor track, the belt having an arcuate path, the belt being supported and guided by a plurality of pressure rollers such that the belt remains in driving contact with the rollers (38).

i 11 14. A conveyor unit according to Claim 13, wherein the drive belt has a substantially arcuate support surface, the surface of the arc being substantially radial at the outermost part of the surface and extending substantially axially at the innermost part of the arc.

15. A conveyor unit according to Claim 13 or Claim 14, wherein the belt is driven via a drive pulley 40 and is guided by two guide wheels and so that the drive belt (39) extends over more 1800 ( rad) of the circumference of the drive wheel.