Abstract:
The quality of cigarettes advancing along a manufacturing line is tested by a method that includes the steps of checking key characteristics of the cigarettes as they pass through testing units placed at given points along the line, so as to obtain first signals reflecting the quality of the tested characteristics presented by each cigarette, inhibiting the operation of reject devices to prevent defective cigarettes from being ejected, then taking up a given number of tested cigarettes as samples at the outfeed stage of the line, including defective cigarettes, and directing them into an auxiliary off-line testing unit by which they are checked a second time so as to obtain a second signal reflecting the quality of the same characteristics; the method also includes the step of sending a signal to the in-line testing units so that, if the first signals differ from the second signals, the in-line units can be recalibrated, thereby optimizing the quality of the cigarettes produced on a given manufacturing line or in a particular batch, and minimizing rejects.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a method and to equipment for testing production quality in a line for manufacturing tobacco products.  
         [0002]     The invention is applicable advantageously to the art field of complete lines for the manufacture of tobacco products, and of cigarettes in particular.  
         [0003]     Such manufacturing lines, to which reference is made explicitly in the following specification albeit implying no limitation, generally comprise a cigarette maker, and a filter tip attachment machine connected to the cigarette maker.  
         [0004]     The invention is concerned with testing various characteristics or properties of cigarettes during their passage along the manufacturing line and at the outfeed of the selfsame line. More exactly, the present invention is concerned with the control and calibration of reject devices positioned along the manufacturing line.  
         [0005]     Conventionally, as cigarettes are formed and fed along a manufacturing line, they will undergo a number of tests each serving to verify that a given characteristic registers within certain limits.  
         [0006]     Among the characteristics of cigarettes subjected to such tests, certain items are of key importance: the weight, the consistency of the filler at the cut ends, the degree of ventilation, the quality of the print, the integrity of the paper wrap, and the soundness of the join between filter and cigarette.  
         [0007]     These quality control steps are implemented along the manufacturing line by dedicated testing units connected to suitable reject devices by which any cigarettes detected as not being in conformity with the aforementioned limits are taken up and ejected automatically, in response to an instruction from the selfsame testing units.  
         [0008]     To this end, the testing units positioned along the line are supplied with signals reflecting the single physical parameters noted above, by sensors placed to monitor the characteristics as the cigarettes advance, which they then compare with previously programmed limit values.  
         [0009]     These limit values must be programmed into each of the testing units according to the quality of cigarette required either from a particular system, in which case the values are entered at the time of installation, or for a particular production batch. Closer limits will result in a higher quality of end product and a higher percentage of cigarettes rejected during production.  
         [0010]     It can happen during the manufacturing cycle that the malfunction of a testing unit will have the effect of altering the programmed limit values, causing the system to reject cigarettes of which the characteristics were in reality within normal limits, or fail to reject cigarettes of which the characteristics were in reality outside the normal limits.  
         [0011]     The object of the present invention is to provide a method and equipment wherein the testing and reject devices positioned along a manufacturing line for tobacco products can be calibrated with ease according to production requirements dependent on the site where the line is installed and/or on the particular manufacturing cycle.  
       SUMMARY OF THE INVENTION  
       [0012]     The stated object is realized according to the -present invention in a method for testing the quality of production in a tobacco product manufacturing line, including the steps of checking a characteristic of tobacco products advancing along a manufacturing line by means of an in-line testing unit in order to obtain a first signal reflecting the quality of the tested characteristic presented by each product, sampling a predetermined number of tested tobacco products taken from the outfeed stage of the line and directing them into an off-line auxiliary testing unit, checking the characteristic by means of the auxiliary testing unit in order to obtain a second signal reflecting the quality of the tested characteristic presented by each product, comparing the first signal with the second signal and, in the event of the first signal differing from the second signal, sending a correction signal to the in-line testing unit and effecting a recalibration of the selfsame unit.  
         [0013]     The aforementioned object is realized similarly in equipment for testing the quality of production in a line for the manufacture of tobacco products, comprising at least one testing unit placed along the manufacturing line and serving to examine and check a given characteristic of tobacco products advancing along the line in order to obtain a first signal reflecting the quality of the tested characteristic presented by each product, also a sampling device placed to take up a certain number of tested tobacco products from the outfeed stage of the line and direct them into an off-line auxiliary testing unit such as will examine and check the characteristic in order to obtain a second signal reflecting the quality of the tested characteristic presented by each product; the auxiliary testing unit is connected to the in-line testing unit, able to compare the first signal and the second signal and programmed, in the event of the first signal differing from the second signal, to send a correction signal to the in-line testing unit for the purpose of effecting the calibration of this same unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:  
         [0015]      FIG. 1  shows the layout of equipment for testing production quality, associated with a cigarette manufacturing line, illustrated schematically and in perspective;  
         [0016]      FIG. 2  is a block diagram illustrating the operation of the equipment shown in  FIG. 1 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]     With reference to  FIG. 1 , numeral  1  denotes a production line, in its entirety, for the manufacture of tobacco products such as cigarettes, denoted  2 , comprising a cigarette maker  3  and a filter tip attachment machine  4  each incorporating a plurality of devices and machine units that will be described in due course.  
         [0018]     Associated with the line  1  is equipment denoted  5  in its entirety, for testing the quality of production, of which a more detailed account will be given in due course.  
         [0019]     The cigarette maker  3  comprises a plurality of the aforementioned devices and machine units and, more exactly, is equipped at the upstream end with a carding unit  6  in receipt of tobacco from an infeed hopper (not illustrated); proceeding downstream, the tobacco is taken up onto a carding drum  7  and projected by an impeller roller  8 , operating in conjunction with the carding drum  7 , into a descent duct or chute  9 , thence onto a belt conveyor  10  and into an ascent duct or chimney  11 .  
         [0020]     The top end of the chimney  11  is enclosed by an aspirating belt  12  on which the tobacco particles collect and are formed gradually into a continuous stream  13  that will ultimately provide the filler for the cigarettes  2 .  
         [0021]     The stream  13  of tobacco is released onto a strip of paper  14  decoiling from a roll  15  along a path that passes initially through a printing device  16 , and advances into a garniture section  17  where it is enveloped longitudinally by the aforementioned strip  14  to form a continuous cigarette rod  18 .  
         [0022]     Whilst reference is made in the specification to a line manufacturing a single cigarette rod, the invention will also find application advantageously in dual or triple rod type cigarette makers.  
         [0023]     The continuous rod  18  advances toward and through a cutting station  19  where it is divided up by a rotary cutter device  20  into discrete segments of predetermined and constant length, and more exactly into sticks  21  of length measuring twice the length of a stick making up a single cigarette  2 .  
         [0024]     Numeral  22  denotes a device by which the double length sticks  21  are transferred, through a set of infeed rollers  23  forming part of the filter tip attachment machine  4 , to a cutting station  24  where each successive double length stick  21  is separated into two single cigarette sticks  25  by the action of a roller  26  and a disc cutter  27 .  
         [0025]     The single cigarette sticks  25  are directed from the roller  26  of the cutting station, first onto a distancing roller  28  on which the two sticks  25  separated by each cutting stroke are spaced apart axially one from the other, then onto an assembling roller  29 , whereupon a double length filter plug  30  supplied by a respective feed unit, denoted  31  in its entirety, is interposed between the two single sticks  25  of each advancing pair.  
         [0026]     The resulting assemblies, each consisting of two single cigarette sticks  25  and one double length filter plug  30  placed between them, are released from the assembling roller  29  onto a roller  32  that forms part of a finishing station  33 , comprising a unit  34  by which tipping papers  35  are cut and fed to the selfsame station  33 , and a rolling device  36  such as will take up the stick/double-filter/stick assemblies and the tipping papers  35  and roll each successive tipping paper  35  about a corresponding assembly to fashion a double length cigarette  2 .  
         [0027]     The double length cigarettes  2  are fed by way of an intermediate roller  37  to a cutter device  38  and divided by a cutting stroke made through the double length filter  30  to generate two successions of single filter cigarettes  2  appearing identical one to another.  
         [0028]     The two successions of filter cigarettes  2  are directed toward an outfeed stage  39  of the filter tip attachment machine  4 , advancing first onto an overturning roller  40  by which a single succession of cigarettes  2  is established, then passing onto a final train of rollers denoted  41  in its entirety, along which the cigarettes  2  will undergo further finishing steps of a familiar nature.  
         [0029]     As illustrated in  FIG. 1  for example, the final train  41  of rollers, supported together with the aforementioned rollers  23 ,  26 ,  28 ,  29  and  32  by a vertical bulkhead A associated with the frame B of the filter tip attachment machine  4 , comprises a roller denoted  42  on which ventilation holes are pierced in the cigarettes  2  by a laser generator device  43 , and a roller denoted  44  on which the cigarettes are scanned.  
         [0030]     Still referring to  FIG. 1 , the quality control equipment  5  according to the invention comprises at least one testing unit  45  placed along the line  1  and furnished with sensors  46 , shown schematically in the drawings, by means of which to examine at least one characteristic of the cigarettes  2  advancing along the selfsame line  1 .  
         [0031]      FIG. 1  shows a number of such testing units  45 , represented schematically by blocks, positioned at different points along the line  1  and serving for example to monitor the weight of each cigarette, the consistency of the end fill, the degree of ventilation, the quality of the print, the integrity of the paper wrap, and the soundness of the join between cigarette stick and filter tip.  
         [0032]     The testing units  45  are also connected to reject devices  47 , likewise positioned at different points along the production line  1 , serving to take up and eject any cigarettes  2  that do not conform to the quality control parameters programmed into the testing units  45 .  
         [0033]     In effect, the sensors  46  are placed along the line  1  in such a way as to scan the cigarettes  2  and identify a value for each one in respect of a given characteristic, thereupon generating an output signal  48  that is received and processed by the respective in-line testing unit  45 .  
         [0034]     The testing unit  45  is able to compare the value of the signal with a respective reference value X or range of values ΔX programmed into the unit  45 , in such a manner that the cigarettes  2  advancing along the production line  1  can be separated into a set of defective items, in which the value measured for the tested characteristic does not match the reference value X or does not register within the reference range ΔX, and a set of conforming items in which the value measured for the tested characteristic matches the reference value X or registers within the reference range ΔX.  
         [0035]     Thus, the testing unit  45  can generate a first signal  49  reflecting the quality of the cigarette  2  which, during the normal manufacturing cycle, is sent to a respective reject device  47  as an instruction to pick out and eject each cigarette  2  found to be defective.  
         [0036]     More exactly, the first signal  49  in question is an activating signal sent to the reject device  47  when the values measured for the characteristics of the cigarettes  2  do not fall within the reference range ΔX or do not match the reference value X.  
         [0037]     For example, should it emerge from the values processed by the testing unit  45  that certain of the cigarettes  2  formed previously and then flipped by the overturning roller  40  have shed too much tobacco from the ends, the unit  45  will pilot the reject device  47  immediately downstream of the roller  40  to identify and eject these same cigarettes  2 .  
         [0038]     Importantly, the position of each cigarette  2  on the line  1  is known at any given moment, so that non-conforming cigarettes can be intercepted and ejected with absolute precision.  
         [0039]     The equipment  5  further comprises an auxiliary testing unit  50  installed off-line and set up to run a full and additional check on the above noted characteristics of the cigarettes  3 . The auxiliary unit  50 , which for example would be of the type disclosed in application B02003A000684 for Italian patent, filed also by the present applicant, is connected on the infeed side by way of a cigarette sampling device, shown as a block denoted  51 , to a roller  52  operating at the outfeed stage  39  of the filter tip attachment machine  4 .  
         [0040]     The auxiliary testing unit  50  also comprises data input and output connections to all of the in-line testing units  45 , of which one only is indicated in  FIG. 2  for the sake of simplicity, so as to form a common interface network  53  ( FIG. 1 ) allowing the exchange of information.  
         [0041]     The equipment  5  is able, in combination with the auxiliary testing unit  50 , to calibrate the in-line units  45  by way of a calibration procedure that will now be described.  
         [0042]     At the moment when the auxiliary testing unit  50  is activated, the reject devices  47  are deactivated temporarily so as to prevent cigarettes  2  flagged as defective along the production line  1  from being ejected; accordingly, these same cigarettes  2  can be intercepted at the outfeed  39  of the filter tip attachment machine  4  and diverted by the sampling device  51  into the auxiliary testing unit  50 .  
         [0043]     The sampling device  51  takes up a predetermined number of cigarettes  2  and transfers them to the auxiliary unit  50  which, through the agency of suitable sensors  54  of which one is illustrated schematically in  FIG. 2 , will identify a value reflecting the quality of a given characteristic presented by each cigarette  2  and generate a relative signal  55 , which is received and processed by a central processing unit  56  of the auxiliary unit  50 .  
         [0044]     The CPU  56  examines the same characteristics as tested previously by the in-line units  45 , so as to generate a second signal  57  reflecting the quality of each characteristic, for each cigarette  2 .  
         [0045]     In addition, the auxiliary testing unit  50  runs a comparison, shown schematically as a block  58  in  FIG. 2 , between the first signal  49  generated by an in-line testing unit  45  and the second signal  57  generated by the selfsame auxiliary unit  50 . Should the first signal  49  reflecting the quality of the characteristic happen to differ from the second signal  57 , a calibration signal  59  is sent by the auxiliary testing unit  50  to the in-line testing unit  45  so as to change the respective reference value X or range of values ΔX programmed into the in-line unit  45 .  
         [0046]     More exactly, the step whereby the aforementioned characteristic is checked by the auxiliary testing unit  50  consists in comparing the value of the characteristic with a respective calibration reference value Y or range of values ΔY programmed into the selfsame auxiliary unit  50 , to the end of identifying a set of defective cigarettes  2 , of which the measured characteristic does not match the calibration value or does not register within the calibration range, and a set of conforming cigarettes  2  of which the measured characteristic matches the calibration value or registers within the calibration range, and thereupon generating a second signal  57  to indicate non-conformity or conformity, respectively.  
         [0047]     The calibration signal  59  sent to the in-line testing unit  45  thus determines the extent of the adjustment required to bring the reference value X or range of values ΔX, stored at the unit  45 , into line with the calibration value Y or range of values ΔY stored at the auxiliary unit  50 .  
         [0048]     The auxiliary testing unit  50  is able to assess all the characteristics of the cigarettes  2  that are monitored by in-line units  45 , and is connected to all of the in-line units  45  so that these can be calibrated simultaneously.  
         [0049]     Once the in-line testing units  45  have been calibrated, the reject devices  47  are reactivated.  
         [0050]     By way of example, the weight of a cigarette  2  measured during its passage along the manufacturing line  1  may register lower than a minimum reference value programmed into the dedicated weight testing unit  45 . The testing unit  45  responds by sending a first signal  49  to the off-line auxiliary unit  50 , indicating non-conformity, whilst the cigarette  2  is allowed to run through without being removed by the reject device  47  (temporarily inhibited).  
         [0051]     The cigarette  2  is then diverted by the sampling device  51  into the auxiliary testing unit  50  and reweighed; if the weight is now found, for example, to be higher than the minimum calibration value, the CPU  56  of the auxiliary unit  50  generates a second signal  57  of conformity which is compared with the first signal  49  of non-conformity received from the in-line unit  45 .  
         [0052]     Since the two signals are dissimilar, the auxiliary testing unit  50  will send the calibration signal  59  so that the minimum reference value of the in-line unit  45  can be raised and brought, for example by successive increments, to the point at which it matches the minimum calibration value stored at the auxiliary testing unit  50 .  
         [0053]     Conversely, if the weight of the cigarette  2  measured during its passage along the manufacturing line  1  is correct, in other words greater than the minimum reference value, the testing unit  45  sends a signal  49  to the auxiliary unit  50  indicating conformity. If, when the cigarette  2  is reweighed by the auxiliary unit  50 , its weight happens to register lower than the minimum calibration value, the CPU  56  of the unit  50  will generate a second signal  57  of non-conformity that is compared with the first signal  49  of conformity received from the in-line unit  45 .  
         [0054]     Since the two signals are dissimilar, the auxiliary testing unit  50  will send the calibration signal  59  so that the minimum reference value of the in-line unit  45  can be lowered to the point of matching the minimum calibration value stored at the auxiliary testing unit  50 .  
         [0055]     In this instance, deactivation of the reject device  47  would not be necessary.  
         [0056]     The calibration value Y or range of values ΔY for each measured characteristic having been programmed manually into the auxiliary testing unit  50 , the unit will be able to adjust the reference value X or range of values ΔX of all the in-line units  45  and reject devices  47  automatically, thereby optimizing the quality of the cigarettes  2  turned out on each line or in the course of each production run.