GB2188604A - Conveyor system for rod-like articles - Google Patents

Abstract

Cigarettes in multi-layer stack formation are delivered from a maker (10) to a packet (12) on a path having a first junction (24) connected to a tray filling unit (30) and a second junction (34) connected to a tray unloading unit (38). Control means (54-72) is provided to control transfer of cigarettes at the first junction (24) according to the capacity of a reservoir (46) associated with the path. The control means (54-72) prevents too frequent operation of a gate (32) associated with the first junction (24) and allows operation of the tray filling unit (30) at an optimum speed. <IMAGE>

Description

SPECIFICATION Conveyor system for rod-like articles This invention relates to conveying rod-like articles, particularly articles ofthe tobacco industry such as cigarettes orfilter rods.

In the cigarette industry it is known to link a machine for producing rod-like articles, e.g. a cigarette making machine orfilter rod making machine, to a trayfiller or similar machine for placing the articles in containers.

Subsequently the full containers are unloaded by a tray unloaderorthe like and delivered to a receiving machine, e.g. a cigarette packing machine or filler rod pneumatic distribution unit. It is also known to form rod-like articles into a substantially continuous stream for delivery from a producing machine to a receiving machine. It is further known to provide means for loading containers from such a stream and means for unloading the contents of containers for delivery to the stream. Examples of systems such as this are is closed in British patent specification Nos. 1404142, 1557458, and 2142894. The present invention is particularly but not exclusively applicable to systems disclosed in said specification No. 214289a,.

According to one aspect of the invention a conveyor system for rod-like articles includes a delivery device, a receiving device, conveyor means for conveying rod-like articles in multi-layer stack formation on a path between the delivery device and the receiving device, and a junction on said path for transferring articles between said path and a subsidiary path, including means for sensing a speed associated with the delivery device or an upstream part ofthe conveyor means, means for sensing a speed associated with the receiving device or a downstream part of the conveyor means, and means for controlling transfer of articles between said path and said subsidiary path, said controlling means having first and second operative conditions according to the difference between said speeds.

Preferably the controlling means includes means for inhibiting transfer of articles between said path and said subsidiary path if said speeds differ by less than a predetermined amount.

In this case preferably the conveyor system includes a variable capacity reservoir associated with said path, means for sensing the capacity of said reservoir, and means for overriding said inhibiting means to allow transfer between said path and said subsidiary path when said capacity sensing means indicates that the capacity of said reservoir has attained a first critical value. Preferably said inhibiting means is reinstated when said sensing means indicates that the capacity of the reservoir has attained a second critical value.

In a preferred arrangementthejunction and subsidiary path are connected to a deviceforstoring rod-like articles, e.g. a tray filler, and when the delivery device has a speed which exceeds the receiving device by a relatively small amount(e.g. less than 10%) the inhibiting means prevents transferto the subsidiary path until a reservoir associated with the main path has filled to a first critical value. The inhibiting means is then overriden and articles are transferred to the storing device. If the quantity of articles in the reservoir falls to a second critical value the inhibiting means is reinstated and the cycle repeats if the speed of the delivery device and receiving device continue to differ by less than said predetermined amount.Preferably ifthe speeds differ by more than said predetermined amount the inhibiting means is overriden irrespective ofthe capacityofthe reservoir.

The subsidiary path may lead to a storage device in the form of a reversible reservoir for rod-like articles in multi-layer stack formation, such as Molins OSCAR. The controlling means could include control meansfor reversibly operating the reservoir.

The controlling means may comprise inhibiting means which stops or prevents operation of conveyor means associated with said subsidiary path, and/or it may comprise physical blocking means in the form of a closure device for blocking the subsidiary path ator adjacent the junction. For example, a rolling band closure of the type disclosed in British patent specification No. 2066761 may be used or, alternatively, a closure of the type disclosed in British patent application No. 43409097 may be used. The disclosure of said application is hereby incorporated herein in its entirety.

The invention is particularly usefully applied in a conveyor system incorporating a junction leading to a tray filling unit where, if the speed of the delivery device exceeds that of the receiving device by a relatively small amount, there would be a tendencyforthe articles to be passed to the subsidiary path frequently and/or at a slow rate. This is often undesirable, particularly where the articles are cigarettes, since it may leadto degradation of the articles. In particular, frequent operation of inhibiting means such as a closure device is preferably avoided.

By providing a reservoir which has a capacity beyond its normal operating level it is possible to ensurethat under normal conditions successive transfer operations are separated by a predetermined time interval. The speed of movement of articles ofthe subsidiary path, e.g. to the tray filler, may be selected so thatthetime taken for the reservoir capacity to resume its normal value (i.e. the second critical value) from its maximum or high capacity (i.e. at its first critical value) is approximately equal to the time taken for the reservoir capacityto increase from its normal to its maximum level when transfer is prevented.

By way of explanation, the term "means for sensing a speed" as used herein is intended to include means which responds indirectly to speed. Thus, for example, means responsiveto net flow rate, such as level sensors used conventionalyto control conveyance of cigarettes in multi-layer stack formation, are regarded as speed sensing means at least for the reason that they can respond to a change in speed. Similarly other sensors not directly measuring speed are included, as are sensors directly measuring the speed of a driven conveyor for exampie.

According to another aspect ofthe invention a conveyor system for rod-like articles includes a delivery device, a receiving device, conveyor means for conveying rod-like articles in multi-layerstacinformation on a path between the delivery device and the receiving device, and a junction on said path for transferring articles between said path and a subsidiary path, means for conveying articles-on said subsidiary path, means for sensing a speed associated with the delivery device or an upstream part ofthe conveyor means, means for sensing a speed associated with the receiving device or a downstream part of the conveyor means, and control means for controlling transfer of articles between said path and said subsidiary path, said control means including means for intermittently transferring articles at a rate which is not directly related to the difference between said speeds.

The control means may include means for transferring articles at a predetermined rate, preferably with predetermined minimum intervals between periods of operation. A variable capacity reservoir may be associatedwith said path,said control means being arranged sothatarticles are transferred to orfrom said reservoir respectively when articles are transferred from orto said subsidiary path. The control means may be arranged to adjusttheflow of articles between said reservoir and said path to return the capacity of said reservoir to a predetermined level following transfer of articles between said path and said subsidiary path.

The control means may be arranged to temporarily adjust the speed of the delivery device or the receiving device when articles are transferred between said path and said subsidiary path.

According to a further aspect of the invention a conveyor system for rod-like articles includes a delivery device, a receiving device, conveyor means for conveying md-like articles in multi-layer stackformation along a path between the delivery device and the receiving device, at least one junction on said path at which articles may be transferred between a subsidiary path and said path, a variable capacity reservoir associated with said path at a location spaced from said junction, means for sensing the capacity of said reservoir, and means for controlling transfer of articles at said junction according to signals received from said sensing means. The controlling means may include means for inhibiting transfer at said junction when said reservoir contains less than a predetermined quantity of articles.

The junction may be connected to a device, e.g. a tray filler, for receiving articles from the path when the rate of operation of the delivery device exceeds that of the receiving device so that there is a net system excess. The arrangement may be used in this instanceto inhibit continuous or frequent flow to or from the path atthe junction. Such a junction may be provided with physical means for blocking a subsidiary path leading from the junction. Such means may take the form of a gate or other closure device projectable across said subsidiary path and forming a part of said inhibiting means.It may be undesirableto operate such a closure device frequently where the speeds of the delivery device and receiving device are relatively similar and it is not possible or it is undesirable to operate the tray filler or other device connected to the subsidiary path at a slow rate corresponding to the difference between said speeds.

Alternatively the junction may be connected to a device, e.g. a tray unloader, for deliverying articles to the path when the rate of operation of the receiving device exceeds that of the delivery device. The inhibiting means may include a closure device at or adjacent said junction and/or control means for conveying articles along a subsidiary path leading to said junction.

The system may include first and second junctions and first and second subsidiary paths, first conveying means for conveying articles away from said first junction on said first subsidiary path, second conveying means for conveying articles towards said second junction on said second subsidiary path, said controlling means including means for selectively controlling operation of said first and second conveying means according to said signals. The controlling means may prevent simultaneous operation of the first and second conveyor means.

According to a further aspect of the invention a conveyor system for rod-like articles in multi-layer stack formation includes first and second junctions, first conveyor means upstream of said first junction, second conveyor means downstream of said second junction, and intermediate conveyor means between said first and second junctions, including means for connecting said first and intermediate conveyor means for common drive, and means for connecting said intermediate and second conveyor means for common drive.

In a preferred arrangement a subsidiary path for receiving articles from the system extends from said first junction and a subsidiary path for supplying articles to the system extends to said second junction. Preferably said first and intermediate conveyor means are under common drive when articles are supplied to said system from said second junction, and said intermediate and second conveyor means are undercommon drive when articles are received from said system from said junction.

The invention will be further described, by way of example only, with particular reference to the accompanying diagrammatic drawing, which shows a conveyor system for cigarettes.

The conveyor system extends between a cigarette making machine 10 and a cigarette packing machine 12, and includes endless band conveyors 14,16,18,20, and 22, which convey cigarettes in stack formation on a path from the making machine to the packing machine.

A gap between The conveyors 16 and 18 defines a junction 24 from which a path 26 extends downwards to another endless band conveyor 28 which leads to a trayfilling unit 30. A reversible gate 32 may be projected across the path 26 at the junction 24 to block passage of cigarettes on said path. The gate may be substantially as disclosed in British patent specification No.2066761, or in British patent application No.8409097.

The conveyor system includes anotherjunction 34, which is downstream ofthe junction 24 and at which an inclined path 36 meets the path defined by conveyors 20 and 22 just downstream of the end of conveyor 20.

The path 36 receives cigarettes from a path leading from atray unloaderunit38 and including endless band conveyors 40,42, and 44. A pivoted gate 45 is arranged to close the path 36 when cigarettes are not conveyed from the tray unloader 38.

At the end of the conveyor 22, and above the packing machine 12, a variable capacity buffer reservoir 46 is provided. Aflexible membrane 48 confines the cigarettes in the reservoir 46. A chute 49 leads to the packing machine 12 from the reservoir46.

The tray filler 30 and tray unloader 38 may be substantially as described in British patent specification No.

2142894, and means may be provided for conveying trays between the filler and the unloader. The tray filler 30 and tray unloader 38 may be disposed substantially as shown in Figures 12-18 of said application: in this instance the filler and unloader are disposed at 900 to each other and the path 26 would preferably comprise a 900 twisted downdrop.

In the drawing lower band conveyors 14, 16 etc. only have been shown, for clarity. Upper endless band conveyors for controlling the upper surface of a stackon the lower conveyors are normally provided.

The conveyor bands 14,16 and 18 are driven bya motor 50which has a motorcontroller 52 which receives signals from a sensor 54 located at the position where the stack is formed or received on the conveyor 14 from the making machine 10. The conveyor band 22 is normally driven by a motor 56 having a motorcon- troller 58 receiving signals from a sensor 60 resting on the membrane 48 of the reservoir 46. The conveyor 28 is controlled by a motor 62 having a motor controller 64 and receiving signals from a sensor 66 above the junction 24. The conveyor bands 40,42, and 44 are driven by a motor 68 having a motor controller 70 and receiving signals from a sensor 72 above the junction 34.Itwill be understoodthatthetrayfilling unit S0 and tray unloading unit 38 are operated at speeds appropriate to the speeds of the conveyors 28 and 40 respectively. The conveyor 20 may be driven at the speed of the conveyors 14, 16, and 18 by engagement of a first clutch unit 74, or at the speed of the conveyor 22 by engagement of a second clutch unit 76. The gate 32 at the junction 34 is operated by a solenoid-controlled air cylinder 78.

The signals from the sensors 54,60,66, and 72, the motor controllers 52,56,64, and 68, clutches, 74,76, and cylinder 78 are under overall control of a circuit including a microprocessor (not shown) which imposes certain conditions on their operation and performs other functions to control operation ofthe system. Each of the motor controllers 58,64, and 70 is controlled by the microprocessor in such manner that enable signals must be provided respectively on lines 80,82, and 84to allow operation ofthe respective motor. The enable signals on lines 82 and 84are normally mutually exclusive, sothatthetrayfilling unit 30 and the trayunload- ing unit 38 cannot operate together.

In operation, cigarettes are conveyed from the maker 10 to the packer 12 by way of conveyors 14, 16, 18,20, and 22. Conveyor 22 is driven at such speed by motor 56 under control of sensor 60 that the sensor remains at or returns to a mean or normal position (indicated by the full line position of membrane 48). Similarly, the conveyor 14 is driven by the motor 50 at a speed dictated by the position of sensor 54. Rate signals aretaken from the controllers 52 and 58, on lines 86,88, respectively, as indications of the current speeds of the making machine 10 and packing machine 12, and are fed to the microprocessor. Alternatively, or additionally, such signals may be taken directly from the makine machine lOand/or packing machine 12.

If the rate signal from the controller 52 orthe making machine 10 (hereinafter referred to simply as maker speed) is the same as the rate signal from the controller 58 or the packing machine 12 (hereinafter referred to as packer speed) then the system is balanced and the following conditions apply. The gate 32 extends across the junction 24 closing the path 26, clutch 74 is activated and clutch 76 is deactivated, so that conveyor 20 moves at the same speed as conveyors 14, 16, and 18. Since the system is in a balanced condition the speed ofconveyor 22 will be substantially the same as that of conveyors 14,16,18, and 20.

If the maker speed is less than the packer speed the same conditions apply as when the system is in balance, exceptthat an enable signal is present on line 84. The motor controller 70 receives a signal directly from the microprocessor to drive the motor 68 at a speed appropriate to the difference between the maker and packer speeds. Signals from the sensor 72 provide fine control of this speed if necessary. Cigarettes unloaded from a tray at the tray unloading unit 38 are delivered onto the conveyor 22 underneath the sensor 72. The pivoted gate 45, which is lightly biased into the closed position (e.g. by a spring or counterbalance weight), is merely pushed aside by the cigarettes advanced by the conveyor 44.When there is no longer a requirementforcigarettesfrom the tray unloader 38 and the conveyor 44 consequently stops, the bias pressure on gate 45 is sufficient to progressively and gradually close the path 36 and retain the upstream cigarettes against gravity. The closing action of the gate 45 is relatively gentle and allows cigarettes to trickle past the gatefor a shortwhile afterthe conveyor44 hasstopped.

When the maker speed is greater than the packer speed the microprocessor controls the system differently depending on whether the maker speed exceeds the packer speed by more or less than a threshold value (e.g.

5-10%). The threshold value may be selected to reduce unnecessary operation of the tray filling unit, and hence of the gate 32, when the net system excess is such that the reservoir 46 can absorb the excess fora reasonable time (e.g. at least 20 seconds) before reaching its maximum capacity.

If the maker speed exceeds the packer speed by more than the threshold value then there is a net system excess which is considered sufficientto require normal operation of the tray filling unit 30. Hence the gate 32 is opened, an enable signal is present on line 82, clutch 76 is activated and clutch 74 deactivated so that conveyors 20 and 22 are driven at the same speed, and motor 62 is driven at a speed appropriate to the difference between the maker speed and packer speed (e.g. by signal direct from the microprocessortothe controller 64 along line 82). Signals from the sensor 66 junction 24 provide fine control of this speed if necessary.

If the maker speed exceeds the packer speed by less than the threshold value then the enable signal on line 80 is removed (so that the motor 56 no longer operates to drive conveyor22) and both clutches 74 and 76 are activated so that conveyors 14, 16, 18,20, and 22 operate at the same speed. The gate 32 may be in its open or closed position depending on previous conditions of the system: it will be assumed that the gate is in its closed position. Since the maker speed exceeds the packer speed the excess will progressively fill there- servoir46.When the sensor 60 indicates thatthe membrane 48 has reached the position 48a, in which the reservoir 46 has reached its normal maximum capacity the gate 32 is opened and the clutch 74deactivated.

The conveyor 28 is then driven at a speed selected suchíhatthe membrane 48 of reservoir46 returns to its normal position (indicated by the full line) in about 20-30 seconds (or other preselected period) when maker speed is atthe system maximum. When the sensor 60 indicates that the membrane 48 has reached its normal level the gate 32 is closed and clutch 74 once again activated so that the system conveyors 14-22 once again move atthe same speed. The cycle will then repeat if the maker speed remains greaterthan the packer speed by less than the threshold value.

An example of how the speed of conveyor may be selected follows. Assume that the maker speed is 10,000 c.p.m. (cigarettes per minute), thatthe threshold value is 10% so that the minimum packer speed for operation in the intermittenttrayfiller mode is 9,000 c.p.m., thatthe minimum time required between operations of gate 32 is 30 seconds, and that the capacity of reservoir 46 between normal and maximum positions ofthe membrane 48 is 500 cigarettes. Then the net excess or deficiency in the system which is to be provided or absorbed by the reservoir 46 (dependent on whether the tray filler 30 is or is not operating) is 500 cigarettes in 30 seconds, i.e. a rate of 1,000 c.p.m.

Then: M- F+ R= P where M is the maker speed, F is the trayfiller speed (i.e. speed of conveyor 28), R is the rate of supply of cigarettes from the reservoir 46, and P is the packer speed Therefore F=M-P+R sothatintheexampleabove F = 2,000 c.p.m.

The requirement for a maximum frequency of operation of the gate 32 is to avoid possible cigarette degradation caused by too frequent operation of the gate.

The following points should be noted concerning operation ofthe system. The gate 32 is closed at all times other than when the tray filling unit 30 is in operation: this avoids potential degradation of cigarettes across the downdrop of path 26. The system allows operation of the tray filler 30 and its associated gate 32 to be reduced by providing a buffer capacity in reservoir 46. A buffer reservoir could theoretically be provided in the region of junction 24 but space is limited here and cigarettes would be likely to be subjected to more pressure than in the reservoir 46, which is located in a position of low cigarette pressure. Hysteresis is built into the motor controllers to avoid unnecessary reversals and fluctuations under exact balanced conditions, and to smooth sensor fluctuations.It is possible that the sensors 66 and 72 could simply operate on an on-off principle: the sensors 54 and 60 preferably operate proportionately.

The reservoir 46 performs the additional function of buffering tray changes in the tray unloader unit 38. In the normal position of the membrance 48 the reservoir 46 has sufficient capacity above its minimum capacity (indicated by the dotted line 48b) to supply the packing machine during the short period while a tray is being changed atthe tray unloader unit 38. Subsequently the sensors 60 and 72 increase the respective speeds of motors 56 and 68 to ensure that the reservoir 46 has sufficient capacity beforethe next tray change is required. No such buffering is requiredfortray changes in thetrayfilling unit 30 sincethe unit includes its own buffer reservoir (not shown).

It will be appreciated that 2,000 c.p.m. (which is the speed of the tray filler in the example given above) is a relatively slow speed of operation for a modern tray filling unit. Where possibly more frequent operation of the gate 32 is acceptable the system may be operated under conditions which may be more favourable forthe trayfillerasfollows.

A relatively high optimimum or minimum speed of operation of the tray filler is selected: this may bethe normal maximum speed ofthetrayfillerbutcould be less (e.g. in the range 3,000 c.p.m. - 10,00Pc.p.m.).

Whenever maker speed exceeds packer speed by less than the threshold value and the membrane 48 of reservoir 46 reaches the normal maximum position 48a the tray filler 30 is brought into operation at its predetermined (optimum or maximum) speed, which is unrelated to the difference in speeds between the maker and packer. The tray filler 30 continues to operate until the membrane 48 regains the normal position: this will happen relatively more quickly with a higher speed of operation ofthetrayfiller. This will be repeated as long as the maker speed exceeds the packer speed by less than the threshold value.

If the maker exceeds the packer speed by greater than the threshold value the tray filler may be operated according to the difference in speeds as before. In this case the threshold value may be somewhat higher than the 5-10% previously mentioned, e.g. 20% or more, so that the required speed ofthe tray filler is nottoo low. Preferably, however, when the maker speed exceeds the packer speed by more than the threshold value the tray filler continues to be operated, when required, at the predetermined speed.If this speed is less than the maximum speed ofthe tray filler the speed ofthetrayfillermay be increased (by a signal on line 82) ifthe difference in speeds between the maker and packer exceeds the predetermined speed. If predeternined speed ofthe tray filler is greater than the maximum speed of the maker the tray filler may be operated atthat speed whenever its operation is required (irrespective of the difference in speeds between the maker and packer and irrespective ofwhetherthat difference is greater than or less than any threshold value).

When the tray filler is operated at a speed unrelated to the difference between maker and packer speed it operates intermittentlyfor periods which depend on that difference and also on the capacity of the reservoir 46 between the positions 48 and 48a of the membrane. If it is required to reduce frequency of operation ofthe gate 32 yet retain a high tray filler operating speed that capacity of the reservoir 46 may be increased.

Alternatively, or additionally, the system may be operated so that when the tray filler is required to be operated the speed of the packer may be reduced to allow the tray fillerto be operated at its optimum speed, i.e. at a speed which is greaterthan the difference between the maker speed and the normal packer speed.

The packer speed may be reduced to a value which is equal to the difference between the speed of the maker and that of the tray filler. Alternatively the packer speed may be somewhat higherthan this if the packer reservoir 46 can supplement the feed to the packer. Thus the packer could be run at any speed between maker speed and maker speed reduced by the speed ofthe trayfiller.Where the speed of the packer is not the same as maker speed reduced by the speed of the trayfillerthe supply to the packer is supplemented byflowfrom the reservoir 46. If the reservoir 46 has insufficient capacity to continue supplying cigarettes to the packer while the tray filler is operating the speed of the packer will be reduced when the reservoir level reaches a low limit (e.g. the "normal" position of membrane 48).

It may be arranged that at times other than when the tray filler is in operation the packer speed is similarly temporarily reduced so that the reservoir 46 is filled to allow itto assume sufficient capacity to supplement the supply to the packer when next again operation of the tray filler is required.

It will be understood that control of the speed of the packer is undertaken by the microprocessor and that such speed is subject to modification by a signal passed on line 88.

Claims (9)

1. A conveyor system for rod-like articles, including a delivery device, a receiving device, conveyor meansforconveying rod-like articles in multi-layerstackformation along a path between the delivery device and the receiving device, at least one junction on said path at which articles may be transferred between a subsidiary path and said path, a variable capacity reservoir associated with said path at a location spaced from said junction, means for sensing the capacity of said reservoir, and means for controlling transfer of articles at said junction according to signals received from said sensing means.

2. Aconveyorsystem as claimed in claim 1,whereinthecontrolling means includes meansforinhibiting transfer at said junction when said reservoir contains less than a predetermined quantity of articles.

3. Apparatus as claimed in claim 1 or claim 2, including first and second junctions and first and second subsidiary paths, first conveying means for conveying articles away from said first junction on said first subsidiary path, second conveying means for conveying articles towards said second junction on said second subsidiary path, said controlling means including means for selectively controlling operation of said first and second conveying means according to said signals.

4. Aconveyorsystem as claimed in claim 3, wherein said controlling means prevents simultaneousoperation of said first and second conveying means.

5. Aconveyorsystem as claimed in claim 3 orclaim4,wherein said first and second conveying means respectively include meansfor deliverying articles into successive containers and means for receiving articlesfrom successive containers.

6. Aconveyorsystem as claimed in any of claims 3 to 5, wherein said first junction is upstream of said second junction.

7. A conveyor system as claimed in any of claims 3 to 6, wherein said variable capacity reservoir is located such that transfer of articles to or from said path occurs at a location downstream of said first and second junctions.

8. A conveyor system as claimed in any of claims 1 to 7, wherein said variable capacity reservoir has first and second states offill at which first and second signals are produced by said sensing means, said on trolling means being arranged to respond to said first signal to initiate a transfer operation and to respond to said second signal to stop a transfer operation.

9. Aconveyorsystem as claimed in any of claims 1 to 8, wherein said controlling means is arranged to transfer articles between said path and said subsidiary path at a predetermined minimum rate.