Abstract:
A process for checking rod-like articles, in particular cigarettes ( 12 ), and an apparatus which is suitable for carrying out the process, a moveable testing element ( 20 ), with mounted push rods ( 21 ) displaceable in the axial direction being moved in the direction of the articles, and each push rod ( 21 ) being displace as it strikes against an article and an electrically evaluable signal—actuating signal ( 31 )—being generated as a result and, upon generation of the actuating signal ( 31 ), the position of the testing element ( 20 ) is determined, and the determined position is evaluated

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a process and an apparatus for checking rod-like articles, in particular cigarettes, according to the respective preamble of the independent claims. 
   A process of the generic type and a corresponding apparatus are known from U.S. Pat. No. 6,508,138. The known process is not yet optimum because, in the case of checking formations of articles, with articles positioned incorrectly to a certain extent, e.g. skewed cigarettes, the formation was evaluated as correct overall. Furthermore, a change in the format—in the length—of the articles, up until now, required mechanical adaptation of the testing apparatus. 
   SUMMARY OF THE INVENTION 
   Accordingly, the object of the invention is to provide a testing process and a testing apparatus in the case of which the abovementioned disadvantages are avoided. 
   In order to achieve this object, the process according to the invention is characterized in that, upon generation of the actuating signal, the position of the testing element is determined and the determined position is evaluated. The object is also achieved by a corresponding apparatus according to the invention, which is characterized in that it is possible to determine the position of the testing element and to store and evaluate the determined position in response to the actuating signal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further special features and details of the invention are explained in more detail hereinbelow with reference to an exemplary embodiment illustrated in the drawing, in which: 
       FIG. 1  shows, as an example of a packaging machine, a so-called soft-pack packaging machine for packaging cigarettes, 
       FIG. 2  shows a section through the soft-pack packaging machine, 
       FIG. 3   a  shows a displacement distance of the testing element with an actuating signal supplied by a push rod of the testing element, 
       FIG. 3   b  shows examples of exemplary cumulative frequency curves which are determined over time with all the actuating signals being added, 
       FIG. 4  shows a further use example of the invention in a cigarette turret, 
       FIG. 5  shows further examples of exemplary cumulative frequency curves, and 
       FIG. 6  shows a section through the cigarette turret. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a so-called soft-pack packaging machine as the packaging machine  10 , and the cigarette feed there. A soft-pack packaging machine is known in general. It has a cigarette-feed shaft  11  in a top region. In its bottom region, as the articles which are to be packaged, a multiplicity of cigarettes  12  are illustrated, by the end or filter side which can be seen in plan view, as a circular contour. Provided in a central part of the soft-pack packaging machine is a multiplicity of testing shafts  13 , through which the individual cigarettes  12  pass, one after the other in each case, under the influence of gravity. Each testing shaft  13  is assigned a pressure-exerting slide  14  and a blocking slide  15 . The pressure-exerting slide  14  is provided for pressing in each case at least one cigarette  12  onto a wall of the testing shaft  13 . If a cigarette  12  is secured by the pressure-exerting slide  14  in this way, the cigarettes  12  which are located above the secured cigarettes  12  no longer move, with the result that these are located in a defined position for subsequent testing. The blocking slide  15  is provided in order to block all the testing shafts  13 . When the blocking slide  15  is actuated, all the cigarettes  12  which are located above the blocking slide  15  are secured. Following the testing shafts  13 , the tested cigarettes  12  pass into a collecting region  16 , from which—once again under the influence of gravity—they pass into individual cigarette shafts  17 . 
     FIG. 2  shows a section through the soft-pack packaging machine along line II—II ( FIG. 1 ) through one of the testing shafts  13 , with the result that the interior of this testing shaft  13  is illustrated with the cigarettes  12  contained therein. Provided upstream of the soft-pack packaging machine is a moveable testing element  20  with a number of push rods  21  for testing the tobacco end sides of the cigarettes  12 . The testing element comprises a housing, through which the push rods  21  project outwards. A guide for the push rods  21  is provided within the housing. Also provided within the housing are means  23 , e.g. an induction coil, for triggering an actuating signal when the push rod  21  is deflected (i.e., displaced), and also electronics for storing or processing, and then transmitting the or each actuating signal. The testing element  20  is depicted in  FIG. 1  by the chain-dotted contour in front of the individual testing shafts  13 , above the respective pressure-exerting slides  14 . The testing element  20  executes an oscillating movement (i.e., displacement or deflection), with the result that it moves towards the cigarettes  12  (forward movement) and, in the process, the ends of the push rods  21  strike against the end sides of the cigarettes  12 , as a result of which the push rods  21  are deflected (displaced). Following this testing, the testing element  20  moves away from the cigarettes  12  again (rearward movement), with the result that the cigarettes  12  are released again. The forward and rearward movement (displacement or deflection) of the testing element  20  is illustrated by the double arrow. During the forward movement of the testing element the cigarettes  12  are pressed against a rear wall of the testing shaft  13 , thus resulting in a defined position for all simultaneously checked cigarettes  12 . 
   If a push rod  21  strikes against a cigarette  12  during the forward movement (displacement or deflection, of the checking element  20  and is deflected (displaced) by a certain distance in the process, an electrically detectable signal (the actuating signal) is generated for this push rod  21 . Details regarding the generation of the actuating signal can be gathered from U.S. Pat. No. 6,508,138, filed for the same applicant. If a cigarette  12  has not been completely filled with tobacco, the push rod  21  which strikes against this cigarette  12  is deflected (displaced) at a later stage, i.e. at a different position of the testing element  20 , than a push rod  21  which strikes against an ordinary cigarette. Correspondingly, in such a case, the actuating signal is then also triggered at a later stage, i.e. at a different position of the testing element  20 . 
   In order that the cigarettes  12  in the respective testing shaft  13  are located in a defined position during the testing operation, that is to say during the forward movement of the testing element  20 , it is provided that beneath the cigarettes  12  which are to be tested in each case, as seen in the direction of flow, at least one cigarette  12  is secured in the testing shaft  13  by the pressure-exerting slide  14 . The pressure-exerting slide  14  is illustrated in  FIG. 2  as a dashed contour concealed by the pressed-on cigarette  12 . The cigarette  12  in front of the pressure-exerting slide  14  is secured during the testing operation by being pressed onto the wall of the testing shaft  13 . The blocking slide  15  is located beneath the position of the pressure-exerting slide  14 , as seen in the direction of flow of the cigarettes  12 . Between the pressure-exerting slide  14  and blocking slide  15 , there is space for precisely as many cigarettes as the testing element  20  has push rods  21  for in each case one testing shaft  13 . In the exemplary embodiment, there is space for precisely three cigarettes  12  between the pressure-exerting slide  14 , or the cigarettes  12  which it presses, and the blocking slide  15 , since the testing element  20  has precisely three push rods  21  for each testing shaft  13 . If, during testing of the cigarettes  12 , the defectiveness of one or more tested cigarettes  12  has been established, the defective cigarettes  12  are ejected by ejecting elements, namely compressed-air nozzles  22 . The rear wall of the testing shaft  13  is open at this location, with the result that defective cigarettes  12  are completely removed from the testing shaft  13 . In the process, the pressure-exerting slide  14  and blocking slide  15  are actuated alternately. In other words, when the pressure-exerting slide  14  clears the checking shaft  13 , the latter is blocked by the blocking slide  15 , with the result than only a defined number of cigarettes  12  advance in the checking shaft  13 . If the blocking slide  15  clears the checking shaft  13 , the pressure-exerting slide  14  is then activated so that only the cigarettes  12  in the section between the pressure-exerting slide  14  and the blocking slide  15  drop in the checking shaft  13 . The space between the pressure-exerting slide  14  and the blocking slide  15  should therefore be particularly dimensioned to accommodate the precise number of cigarettes  12  checked in a single checking run made by the checking element  20 . 
     FIG. 3   a  shows a displacement distance  30  of the testing element  20  plotted in a coordinate system. In the coordinate system, the deflection of the testing element  20  is plotted on the y-axis and a time base is plotted on the x-axis. The time base used is preferably a time base which is geared to the operating speed of the packaging machine  10 . For this purpose, it is customary to use, for example, a full revolution of a main spindle assigned, in particular, to the packaging machine  10 . For this purpose, the revolution of the main spindle is measured by an incremental encoder or angle sensor. A certain number of counting pulses, here for example 1000, corresponds to a full revolution of the main spindle. With reference to the illustrated displacement distance  30  of the testing element  20 , it can be seen that the testing element  20  has executed a complete forward movement and a complete rearward movement during a full revolution of the main spindle. The illustrated displacement distance  30  of the testing element  20  over the time base is in the form of a half-wave of a sinusoidal oscillation, as is customary in the case of such oscillating movements. Likewise illustrated is the actuating signal  31  of a push rod  21  which, as a binary signal (actuated/not actuated), is rectangular. As soon as the actuating signal  31  for a push rod  21  is produced, the current position of the testing element  20  is established. It is immaterial here as to whether the position of the testing element  20  is depicted in the form of the existing deflection or in the form of the counting pulses elapsed, since both form a constant relation over a displacement distance  30  of the testing element  20  during a full revolution of the central spindle. 
     FIG. 3   a  illustrates the case where the actuating signal  31  is produced before a maximum deflection of the testing element  20  during the forward movement by, for example, thirty distance units, namely at twenty-eight distance units. One of the push rods  21  thus strikes against the tobacco end side of a cigarette  12  and is consequently deflected such that the actuating signal  31  is triggered before the testing element  20  has completed the forward movement. If one of the push rods  21  were to strike against a cigarette  12  at a considerably earlier stage during the forward movement of the testing element  20 , the beginning of the actuating signal  31  shifts to the left on the y-axis. Earlier triggering of the actuating signal  31  may be caused by a cigarette  12  which is too long. If the cigarette  12 , by contrast, is too short or has not been filled with sufficient tobacco, the beginning of the actuating signal  31  correspondingly shifts to the right on the y-axis. 
   Two limit values  32 ,  33  are used in order to evaluate the actuating signal  31 , in which case, with an actuating signal  31  generated within these limit values  32 ,  33 , the respective cigarette  12  is evaluated as still being defect-free, and a cigarette  12  which has triggered an actuating signal  31  outside these limit values  32 ,  33  is evaluated as defective, with the result that an error signal is generated correspondingly. 
   The individual evaluation of all the actuating signals  31 , in the case of a multiplicity of testing shafts  13  and the plurality of cigarettes  12  which are checked in each testing shaft  13  during a testing operation, is only practicable to a certain extent. In actual fact, in the exemplary embodiment illustrated with twenty-eight testing shafts ( FIG. 1 ) and in each case three cigarettes  12  tested in a testing shaft  13  during a testing operation ( FIG. 2 ), eighty-four actuating signals  31  would have to be checked. It is thus preferably provided that the actuating signals  31  are added over the time base and a resultant cumulative frequency curve  34 ,  35 ,  36  is evaluated rather than the individual actuating signals  31 .  FIG. 3   b  illustrates a plurality of such cumulative frequency curves  34 ,  35 ,  36 . Each cumulative frequency curve  34 ,  35 ,  36  begins, during the forward movement of the testing element  20 , at a zero height because, in the first instance, none of the push rods  21  is deflected and, correspondingly, no actuating signal  31  is produced. Each cumulative frequency curve  34 ,  35 ,  36  correspondingly terminates at the zero height because, at some point during the rearward movement of the testing element  20 , a position is reached at which, once again, none of the push rods  21  is deflected, so that, correspondingly, no actuating signal  31  is produced. Furthermore, each cumulative frequency curve  34 ,  35 ,  36  reaches a maximum at the turning point of the movement of the testing element  20  because, at this location, all the push rods  21 , or at least most of the push rods  21 , are deflected and a corresponding number of actuating signals  31  is thus produced. If all the push rods  21  are deflected at this position, eighty-four actuating signals  31  are correspondingly produced for eighty-four push rods  21 , with the result that the cumulative frequency curve  34 ,  35 ,  36  has a height of eighty-four units. 
   Depending on whether the cigarettes  12 , by way of a uniform format or by way of a uniform tobacco filling, are approximately the same length, the push rods  21  are deflected in close temporal succession. A first method of checking the cumulative frequency curve  34 ,  35 ,  36  is to check the duration of the rise starting from a first threshold value as start value  37 , in particular zero, up to a second threshold value as maximum value  38  in respect of the respective position of the testing element  20  when the start value  37  and maximum value  38  are reached. In the case which is illustrated in  FIG. 3   b , it is only the rise of the cumulative frequency curve  34  from the start value  37  up to the maximum value  38 , said curve being illustrated by solid lines, which takes place within the two limit values  32 ,  33  for the position of the testing element  20 . In the case of the cumulative frequency curve  35  which is illustrated by chain-dotted lines, although the maximum value  38  is reached within the interval predetermined by the limit values  32 ,  33 , the start value  37  is reached before the interval, which indicates that some push rods  21  have been deflected “too early”, with the result that, among the tested cigarettes  12 , at least some of the cigarettes  12  were longer than expected or envisaged. In the case of the cumulative frequency curve  36  which is illustrated by dashed lines, it is only the start value  37  which is reached within the interval defined by the limit values  32 ,  33 , while the maximum value  38  is only reached outside the interval. This indicates that a multiplicity of the push rods  21  have been deflected “at a relatively late stage” during the forward movement of the testing element  20 , with the result that, among the cigarettes  12  tested, there are a considerable number of cigarettes  12  which are either too short or have not been filled with sufficient tobacco. It is sufficient to carry out the evaluation only during the forward movement of the testing element  20  because corresponding conditions are present during the rearward movement and the profile both of an individual actuating signal  31  and of a cumulative frequency curve  34 ,  35 ,  36  is symmetrical to the displacement distance  30  of the testing element  20 . Furthermore, it is sufficient for the evaluation also to be carried out merely over certain parts of the forward movement of the testing element  20 . In the illustrations, the positions X and Y respectively designate the beginning and the end of the evaluation. The interval which is defined by the abovementioned limit values  32 ,  33  is illustrated as a hatched region in  FIG. 3   b . In order to adapt the checking process to cigarettes of differing lengths, for example, after a change of product or brand, a shift in the evaluation section delimited by the X and Y positions is sufficient. When checking cigarettes that are longer on the whole, the push rod  21  is namely deflected at an earlier point in time, thus “farther to the left” in  FIG. 3   b , resulting in an overall widening of cumulative frequency curve  34 ,  35 ,  36 . When checking cigarettes that are on the whole shorter, the push rod  21  is deflected at a correspondingly later point in time, i.e. “farther to the right” in  FIG. 3   b , resulting in an overall narrowing of the cumulative frequency curve  34 ,  35 ,  36 . 
   An alternative possibility for checking the cumulative frequency curve  34 ,  35 ,  36  is to check the duration over which the respective cumulative frequency curve  34 ,  35 ,  36  exceeds a threshold value  39 . In this case, the number of time units during which the respective cumulative frequency curve  34 ,  35 ,  36  runs above the threshold value  39  are counted. The cumulative frequency curve  35 , which is illustrated by chain-dotted lines, runs above the threshold value  39  for the longest period of time. It has already been explained above that a cumulative frequency curve of the type  35  which is illustrated by chain-dotted lines is established when, among the cigarettes  12  tested, a multiplicity of the cigarettes  12  are too long. In contrast, the cumulative frequency curve  36 , which is illustrated by dashed lines, only runs above the threshold value  39  for a short period of time. In this respect, it has already been explained above that such a cumulative frequency curve  36  is established when, among the cigarettes  12  tested, many of the cigarettes were too short or only filled with insufficient tobacco. 
   In order to evaluate the cumulative frequency curves  34 ,  35 ,  36 , a lower and an upper temporal threshold value are introduced, the lower temporal threshold value being selected such that the duration over which the cumulative frequency curve  36 , which is illustrated by dashed lines, exceeds the threshold value  39  falls below this temporal threshold value and the duration over which the cumulative frequency curve  35 , which is illustrated by chain-dotted lines, exceeds the threshold value  39  rises above this temporal threshold value. Correspondingly, the duration over which the cumulative frequency curve  34 , which is illustrated by solid lines, exceeds the threshold value  39  comes between these lower and upper temporal threshold values, with the result that this cumulative frequency curve  34  can be evaluated to the effect that the cigarettes  12  tested fulfill the requirements. 
   In a practical configuration, the respective cumulative frequency curve  34 ,  35 ,  36  can be checked as follows: each push rod  21 , in a memory of a processing unit, is assigned precisely one memory cell (not all are illustrated), the respective memory cell representing the value of the respective actuating signal  31 . That is to say, with the actuating signal  31  triggered, the respective memory cell has a value of “logical one”. A plurality of memory cells here are combined into groups. It is usually the case that eight memory cells are combined, in a manner which is known per se, into a group to form one byte. In the case of eighty-four push rods  21 , in order to represent the respective states, it is thus the case that ten bytes (=eighty memory cells) and four further memory cells are necessary. These four further memory cells are completed by four additional memory cells, which are set to “logical one” as standard, to form a further byte. During the movement of the testing element  20  or a selected part of this movement, these eleven bytes are permanently subjected to a logical AND operation and the consequent logic result is evaluated. As long as one of the push rods  21  has not been deflected to the extent where the corresponding actuating signal  31  is generated, a “logical zero” also remains in the logic result. It is only when all the push rods  21  have been deflected that all the associated memory cells have the value “logical one”, so that it is also only the “logical one” which appears in the logic result. When the logic result contains only logic ones for the first time, the position of the testing element  20  is established. An equivalent result is achieved by establishing the point in time along the time base at which this arrangement occurs. As soon as one of the push rods  21  is released again during the rearward movement of the testing element  20 , the corresponding actuating signal  31  disappears, as does thus the “logical one” state in the associated memory cell. Correspondingly, it is now also the case that the logic result no longer has just “logical ones”; rather, at least one “logical zero” is present. It is also the case when this situation arises that the position of the testing element  20  or the associated point in time is established. If the first position/the first point in time determined in this way or both the positions/points in time determined or the difference between these positions/points in time are located within predetermined limit or threshold values, the cumulative frequency curve  34 ,  35 ,  36  is one in which the cigarettes  12  tested satisfy predetermined criteria. However, if the period of time or the distance covered by the testing element  20  between these two positions/points in time determined is too great (cumulative frequency curve  35 ) or too small (cumulative frequency curve  36 ), the situation detected is one in which at least one of the cigarettes  12  tested does not correspond to the preset requirements. A check of the time profile of the individual actuating signals  31 , which is stored at least in part for this purpose, is then carried out in order to determine which push rod  21  was, or which of the push rods  21  were, deflected too early, too late or at too long or too short a distance, in order then to determine which cigarettes  12  are defective. Cigarettes  12  which are detected as being defective are ejected by means of the compressed-air nozzles  22 . It may be provided that, in the case of at least one cigarette  12  within a cigarette shaft  13  being detected as being defective, all the cigarettes  12  which are secured between the pressure-exerting slide  14  and the blocking slide  15  are ejected. The processing unit, referred to but not shown, is a control unit or the like. That or each testing element  20  is connected with the processing unit in a known fashion, e.g. via the cable connections of the respective testing element  20  as shown in  FIG. 2 ,  FIG. 4  and  FIG. 6 , so that the respective actuation signals can be transmitted on to the processing unit. For evaluating the position of a testing element  20  the processing unit processes the position data which are sent from the incremental encoder or angle sensor. 
     FIG. 4  illustrates a further application of the invention. A cigarette turret  40  which is known per se is provided in order to package the cigarettes  12  in cigarette packs. This turret comprises individual pockets  41 , in which the cigarettes  12  are located in the conventional three-layered formation. The cigarettes  12  are received from the cigarette shafts  17  into the pockets  41  (in the top region of the cigarette turret  14  in the illustration) and, after a corresponding rotation of the cigarette turret  40 , are transferred out of the pockets  41 , for further handling, to following devices, which are not illustrated (in the bottom region of the cigarette turret  40  in the illustration). Between these two positions, monitoring takes place, on the one hand, of the filter ends and, on the other hand, of the tobacco ends of the respective cigarette formation in a pocket  41  in accordance with the principle described above. For this purpose the cigarette formation is secured against undesired shifting along the longitudinal axis of the pocket  41  by a spring steel plate or the like. Provided for the purpose of inspecting the cigarette formation are two mutually opposed testing elements  20  which basically corresponds to the respective testing element  20  already illustrated in  FIG. 2 , but, in respect of the number and position of the respective push rods  21 , are geared to the formation of the cigarettes  12  in a pocket  41 . Both testing elements  20  also execute an oscillating movement, with the result that, during a forward movement, a push rod  21  which strikes against a cigarette  12  is deflected and an associated actuating signal  31  is generated. 
   The cigarette turret  40  is moved cyclically. In each case two pockets  41  are always located in the region of two front and rear testing elements  20 . The rear testing elements  20  are not visible in the illustration in  FIG. 4  due to their position behind the cigarette turret  40 . They are provided for monitoring the filter side of the respective cigarette formation. The front testing elements  20  are correspondingly provided for monitoring the tobacco side of the respective cigarette formation. The front and rear testing elements  20  are shown in  FIG. 6  of the section view along line III—III from  FIG. 4 . Each pair of testing elements  20  executes an oscillating movement. For this purpose each pair of testing elements  20  is mounted on a common support, such as a plate or the like. The oscillating movement of these testing elements  20  corresponds to the movement which has already been illustrated in  FIG. 3   a . The oscillating movement of the respective opposing testing elements  20  is executed such that the respective pair of opposing testing elements  20  are moved simultaneously and equidirectionally to the cigarette formation located in the pocket  41 . At the end of the simultaneous forward movement, the two opposing testing elements also move simultaneously and equidirectionally away from the cigarette formation. The pocket is open at both sides for this purpose so that the pushrods  21  of the opposing testing elements  20  can reach the cigarettes  21  located in the pocket  41 . 
   The individual actuating signals  31  detected for each testing element  20  are added to give cumulative frequency curves  42 ,  43 ,  44 ,  45 , as is illustrated in  FIG. 5 . In comparison with  FIG. 3   b , the height of the respective cumulative frequency curve  42 – 45  is nevertheless lower since, in the case of twenty cigarettes  12  in a cigarette formation, a maximum of twenty actuating signals  31  are triggered by the associated twenty push rods  21  of the respective testing element  20  and the respective cumulative frequency curve  42 – 45  thus has a maximum height of twenty units. The check of the cumulative frequency curves  42 – 46  in respect of exceeding or dropping below certain start, maximum and threshold values  37 ,  38 ,  39 , e.g. within an interval defined by limit values  32 ,  33 , corresponds to the check which has already been described with reference to  FIG. 3   b . Accordingly, an excessively narrow cumulative frequency curve, e.g. the cumulative frequency curve  43  identified by triangles, indicates a cigarette formation with cigarettes  12  which are too short, and an excessively wide cumulative frequency curve, e.g. the cumulative frequency curve  44  identified by circle symbols, indicates a cigarette formation with cigarettes  12  which are too long. A cigarette formation with cigarettes  12  which satisfy the predetermined criteria has a cumulative frequency curve with a rapid rise, which, in respect of width, lies between the two cumulative frequency curves  43 ,  44  which indicate a defective cigarette formation, that is to say, for example, a cumulative frequency curve  42 , as is illustrated by solid lines in  FIG. 5 .  FIG. 5  also illustrates a cumulative frequency curve  45  which is identified by square symbols and is produced, for example, if, in a cigarette formation, one cigarette  12  is skewed in particular in front of the end sides of the other cigarettes  12 , that is to say, for example, a cigarette which has been introduced only part of the way and then broken off. In this case, a large number of push rods  21  of the respective testing element  20  strike against the broken cigarette at a relatively early stage, thus giving rise to the illustrated expansion of the cumulative frequency curve  45 . Using the shape of the cumulative frequency curve  45 , it is thus also possible to draw conclusions about the defect present in each case. 
   Likewise, it is possible to record the moment of pushrod abutment releasing the actuating signals of the individual pushrods  21  and to set it in relation to the moment of pushrod abutment releasing the actuating signals of the pushrod  21  of the opposing testing element  20 . Thus, the opposite testing elements  20  record the actuation signals of those pushrods  21  which contact the same cigarette  12  at the front as well as at the tobacco end. Based on the recorded moment of abutment of these actuating signals, position information can be deduced using the displacement distance  30  of the respective testing element  20 . Information about the length of the respective cigarette  12  can be deduced from the recorded moments for each cigarette  12  of the cigarette formation or from the deducible position information in conjunction with the known distance of the opposing testing elements  20  in a resting position, i.e. in a non-extended state. This deduction, i.e. the calculation of the necessary mathematical or logic operations, are performed by the aforementioned processing unit. The necessary instruction are programmed in the software of the processing unit or implemented in the hardware. If the determined length of the respective cigarette  12  lies within the preset or specified range, the respective cigarette  12  is evaluated as normal. If the determined lengths of all cigarettes  12  of a cigarette formation lie within the range, the entire cigarette formation is evaluated as normal. The cigarette formation can then—in known fashion—be put into a cigarette pack in the further course of the packaging process. By varying the specified or preset range the testing can be reset at any time for new cigarette lengths. 
   If a faulty cigarette length is detected for at least one cigarette  12  of the cigarette formation, an index for tracking this cigarette information is established for the further packaging process. At an appropriate time, the cigarette formation, which may be located in a finished or semi-finished cigarette pack, can be removed from the process.