GB2133759A - Steadying output on a production line - Google Patents

Abstract

Method of steadying output on a line connecting production machinery, in particular, a line (1) carrying masses of rod-shaped items e.g. cigarettes (7) between at least one manufacturing machine (2) and at least one packing machine (3), wherein two storage facilities (18,16), of large and small capacity respectively, are operated parallel and controlled by a circuit so as to provide for gradual long-term operation of the first and only short-term operation of the second for steadying that part of output not steadied continually by the first storage facility (18). <IMAGE>

Description

SPECIFICATION Method of steadying output on a line connecting production machinery The present invention relates to a method of steadying output on a line connecting production machinery, in particular, one for steadying output on a line carrying masses of rod-shaped items, in particular, cigarettes, between at least one manufacturing machine and one packing machine.

On cigarette manufacturing and packing installations, one or more cigarette manufacturing machines are generally connected directly to one or more packing machines over a series of conveyors which form channels along which the cigarettes flow continually in bulk.

As the construction of a cigarette manufacturing and packing installation on which the number of cigarettes produced always equalsthe numberof cigarettes sent through the packing machines would be unthinkable, each ofthe lines formed by the said conveyors is usuallyfitted with compensating stores usually comprising relatively large- and smallcapacity storage facilities.

The said two types of compensating store on each line are generally operated in turn, depending on the amount of output to be compensated. For relatively low and/orshort-term compensation, the smallcapacity stores are generally used, the high-capacity stores being employed solelyforhigh output compensation.

One ofthe major drawbacks on a system ofthis kind lies in the fact that the said high-capacitystores comprise very long conveyors for moving cigarettes in considerable bulk. Consequently, sudden operation, in responseto a sharp variation in supply detected by sensor elements, createsforces of inertia strong enough, in many cases, to break the conveyors.

What is more, as the conveyors on the said stores move along routes comprising spiral sections or bends, in addition to the drawbacks involving the said forces of inertia, centrifugal forces are also generated which tend to throwthe cigarettes radially offthe conveyors along the bends, cause the tobacco to come out of the cigarettes and, in any case, result in disorderlythroughput which often requires frequent assistance from the operator.

The aim ofthe present invention is to provide for compensating the said variation in output supply with none ofthe aforementioned drawbacks.

With this aim in view, the present invention relates to a method of steadying output on a line connecting production machinery, in particular, a line carrying rod-shaped items in bulk between at least one manufacturing mach ine and at least one machine for packing the said items, the said method being characterised by the fact that it provides for the parallel operation of at least one first and at least one second compensating store, both communicating with the said line and having a relatively large and relatively small capacity respectively; the said compensating stores being provided with first and second drive means respectively, the said means being interlocked parallel to detecting means set up on the said line for detecting any variation in output between the said machines; the said first drive means being designed to create a first compensating flow through the said first store for gradual compensation ofthe said output variation, and the said second drive means being designed to create a second compensating flowthrough the said second store so as to compensate continually for any difference between the said first flow and the flow required, at that particulartime, for compensating the said variation.

The invention will now be described by way of a non-limiting example with reference to the attached drawings in which: - Fig. 1 shows a diagram of part of a conveyor line for supplying a cigarette packing machine; - Fig. 2 shows a block diagram of a circuitfor controlling part ofthe Fig. 1 conveyor line.

Fig. 1 shows a conveyor line (1) between a cigarette manufacturing and a cigarette packing installation. In the example shown,the said two installations comprise a manufacturing machine (2) and a packing machine (3). Conveyor line 1, however, may be used for connecting morethan one manufacturing machine (2)to morethan one packing machine (3).

Conveyor line 1 comprises a first channel (4) connected to the output of machine 2 and terminating at the top end of an essentially vertical second channel or duct (5) the bottom end of chich communicates with an input box (6) on machine 3. Channel 4 is filled with a mass of cigarettes (7) produced on machine 2 and arranged crosswise in relation to the larger axis on channel 4. Cigarettes 7 are fed along channel 4 towardsthe top end of duct 5, in the direction indicated by arrow 8, on a conveyor or belt (9) wound round drive rollers 10, only one ofwhich can be seen in Fig.1.

Channel 4 and duct5 connect up at intersection 11 the top of which is defined bya gaugeormovable detector (12) which senses the pressure of cigarettes 7 inside duct 5 and forms part of a detector consisting of detector circuit 13 (Fig. 2). The latter is provided with two outputs (14, 15) from the first of which it supplies a voltage signal proportional to the algebraic difference between the outputspeed of machine 2 and the absorption speed of machine 3, and from the second of which it supplies a voltage signal depending on the real flow of cigarettes along duct 5 and which takes into account the cigarettes (7) sliding along channel 4, any cigarettes taken out of channel 4 by the operator and any rejected on machine 2.

As shown in Fig. I,duct 1, duct 5 communicates, on one side, with a relatively small-capacity compensating store (16) and, on the other, with input duct 17 on a relatively high-capacity compensating store (18) driven either way by motor or drive means 19 (Fig. 2).

Store 16 is defined by two conveyor belts (20, 21 ) wound round respective pairs of rollers (22, 23) driven by motor or drive means 24 (Fig. 2). The opposite branches of the two belts (20,21) are connected by an end panel (25) the position of which along store 16 is detected by a number of sensors (26) which combine to form a filling detector (27) (see also Fig. 2) for supplying a control signal whenever panel 25 moves beyond a given middle section of store 16.

Fig. 2 shows a circuit (28) for controlling two motors (19,24), the said circuit comprising in addition to detector circuit 13, a comparator (29) connected to output 14via a normally-closed switch (30) designed to close switch 31 wheneverthe output signal from output 14 exceeds a given threshold. Switch 31 is set up on a line (32) connecting output 15to the input of integrating device 33. The output of the latter is connected to a first input on an algebraic adding device (34) the output ofwhich controls starting of motor 19 in either direction.

Output 15 on detector circuit 13 is also connected, via line 35 parallel to line 32, to a first input on algebraic adding device 36 a second input of which is connected to the output of integrating device 33 and the output of which controls starting of motor 24 in either direction via a normally-closed switch device (37).

Opening of switch device 37 is controlled by an output signal on detector 27 which is also supplied to a second input on adding device 34.

Operation of conveyor line 1 will now be described starting from a condition of perfect balance with no signals at outputs 14 and 15 of detectorcircuit 13.

If, starting from a condition of perfect balance, output variations occur between machines 2 and 3, detector circuit 13 supplies, via its outputs 14 and 15, two signals, the first of which, being proportional to the output difference between the two machines (2,3), indicates, by way of an absolute value and sign, the theoretical extent by which output has been varied.

Ifthe output signal from 14 fails to exceed the threshold on comparator29,the latter keeps switch 31 open to prevent the output signal from 15 from reaching motor 19 on store 18 which therefore remains idle. The output signal from 15, the value of which depends both on the real variation involved and on which the ouputspeed ofthe system the variation has occurred on, is supplied, via line 35 and adding device 36, to motor 24 on store 16 which is activated at a speed proportional to the output speed of the system so asto restore balance.

If, when performing the said compensation, panel 250n store 16 moves beyondthe middieoptimum operating section defined by detector 27, the latter supplies a signal which opens switch 37, slows, stops and reverses motor 24 and, at the same time, starts motor 19 in such a direction as to create a flow of cigarettes through duct 17, not only to rectify the said outputvariation, butalsoto bring panel 25 backtothe said middle position.Detector 27 may, of course, be designed so that, should the said outputvariation persist, the two stores (16, 18) are operated alternately or, once panel 25 is brought backto the said middle position, motor 24 is stopped and only motor 19 continues runr-ing at reduced speed. Should the output signal from 14 exceed the threshold of comparator 29, the latter supplies a signal which closes switch 31 and, atthe same time, prevents the output signal from 15 from being supplied to lines 32 and 35.

Via line 32, the output signal from 15 sent to integrator device 33 the output signal of which, for starting motor 19, increases more or less gradually and essentially in proportion to the said output signal from 15so as to provideforsteady initial acceleration of motor 19 up to operating speed at which the said output variation is fully rectified by the cigarettes flowing through channel 17.

The input and output signals on integrator 33 are sentto the inputs of adding device 36 which supplies a difference or error signal for starting motor 24 and operating store 16 at a variable speed designed to compensate continually the part of the said output variation not compensated by store 18. The flow of cigarettes through store 16 will obviously be high immediately following the output variation of during the transient phase of motor 19, and will gradually fall off if the outputvariation remains constant. In any case, anyfluctuation in the output variation will be accompanied by an error signal from the output of adding device 36 for starting up motor 24 again.

From the above description, it will be clear that control circuit 28 prevents store 18from being subjected to dangerous acceleration by allowing itto start gradually and to operatesolely over long-term periods, short-term operation being reserved for store 16.

Should switch 30 be opened and switch 31 be kept constantly closed, motors 19 and 24will be operated in the same way as described, regardless of the value of the output signal from 14which may be suppressed.

Claims (9)

1. Method of steadying output on a line connecting production machinery, in particular, a line carrying rod-shaped items in bulk between at least one manufacturing machine and at least one machine for packing the said items, said method being characterised by the fact that it provides for the parallel operation of at least one first and at least one second compensating store, both communicating with the said line and having a relatively large and relatively small capacity respectively; the said compensating stores being provided with first and second drive means respectively, the said means being interlocked parallel to detecting means set up on the said line for detecting any variation in output between the said machines; the said first drive means being designed to create a first compensating flow through the said first store for gradual compensation ofthe said output variation, and the said second drive means being designed to create a second compensating flowthrough the said second store so as to compensate continuallyfor any difference between the said first flow and the flow required, at that particulartime, for compensating the said variation.

2. Method according to Claim 1, characterised by the fact that the said detecting means are designed for supplying an output signal depending both on the extent of the said variation and on the flow of the said itemsthrough a section of the said conveyor line.

3. Method according to Claim 2, characterised by the fact that the said detecting means are designed for supplying a furtheroutput signal proportionaltothe said variation; the said further signal being used by a comparator for cutting off the said first drive means from the said detecting means when the said further signal is below a presetthreshold.

4. Method according to any ofthe previous Claims, characterised by the fact that the said first drive means are connectedtothe said detecting means via an integrating device.

5. Method according to Claim 4, characterised by thefactthatthe said second drive means are connected to the said detecting means via an algebraic adding device, a first input of which is designed to receive the said output signal from the said detecting means, a second input of which is designed to receive an output signal from the said integrating device and one output of which is connected to the said second drive means.

6. Method according to any of the previous Claims, characterised by the fact that the said second store comprises filling detecting means designed to detectthe amount of the said items contained, at any time, inside the second store; the said filling detecting means being designed, for given values ofthe said amount, to reverse the said second drive means and supply a signal to the in put of the said first drive means.

7. Method according to any of the previous Claims,characterised bythefactthatthesaid conveyor line comprises a channel, essentially vertical atthe bottom, which communicates with a box at the input of a first said production machine, in particular, a packing machine; the said first and second store communicating with the said conveyor line along the said vertical channel.

8. Method according to Claim 7, characterised by thefactthatthe said vertical channel communicates at the top with a conveyor connecting a second said production machine, in particular, a manufacturing machine; the said conveyor and the said channel communicating with each otheratan intersection controlled buy a gauge forming part of the said detecting means and designed to supply a signal proportional to the pressure of the said items at the said intersection.

9. Method of steadying output on a line connecting production machinery, essentially as described and shown on the attached drawings.