Abstract:
A handling installation disclosed, in particular for cigarettes. Known installations for handling cigarettes have a reservoir for temporarily storing the cigarettes, a maker ( 10 ) for the cigarettes and a packer ( 11 ). The maker ( 10 ) is arranged upstream of the reservoir ( 12 ) and the packer ( 11 ) is arranged downstream of the reservoir ( 12 ). In known installations, synchronising the action between reservoir ( 12 ), packer ( 11 ) and maker ( 10 ) causes problems. In the disclosed installation, the working speed of the maker ( 10 ) and the packer ( 11 ) is controlled depending on a measured filling level of the reservoir ( 12 ). When the filling level of the reservoir ( 12 ) is low, the working speed of the maker ( 10 ) is increased, when the filling level is high, said speed is decreased. On the contrary, the working speed of the packer ( 11 ) is increased when the filling level is high but reduced when the filling level is low.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a system for handling articles, in particular for packaging cigarettes, having a reservoir or store for temporarily receiving articles, and having at least a first handling machine, in particular a maker for cigarettes, upstream, and at least a second handling machine, in particular a packaging machine, downstream, of the reservoir as seen in the direction of the movement path, it being the case that the first handling machine conveys articles alternatively into the reservoir or to the second handling machine and the reservoir, as required, discharges articles to the second handling machine. 
     In many areas of production or handling technology, different sub-assemblies and/or machines are linked up to one another to form a unit. The articles which are to be handled pass through the different machines one after the other and thus undergo the necessary processing. The sub-assemblies and machines which are combined to form such a system have to be controlled in a coordinated manner and/or co-ordinated with one another in terms of functioning. 
     Systems of the abovementioned type are to be found, in particular, in packaging technology. Finished products pass through in some circumstances a number of machines in order, for example, to be grouped into units and packaged in a number of steps. “Lines” which comprise a number of sub-assemblies and machines are known in the production and packaging of cigarettes. A cigarette production machine, a so-called maker, is adjoined by at least a first packaging machine. However, usually more than one packaging machine is provided, in order for a first, inner wrapping, the actual packaging and an outer, film wrapping to be provided in successive steps. It is difficult in practice to co-ordinate the machines with particularly high outputs. 
     It is known to use stores, so-called reservoirs, which temporarily receive a large number of cigarettes following the maker and discharge these again, as required, to the following packaging machine. It is also known in this case for the maker and packaging machine to be switched off in accordance with a maximum or minimum filling level. For example, it is customary to switch off the maker when the reservoir has reached a filling level of 100% of the maximum capacity. In the same way, the following packaging machine is switched off when the store is completely empty. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to improve the performance and/or the efficiency of such systems which comprise a number of machines and sub-assemblies and use a store for articles. 
     In order to achieve this object, the system according to the invention is characterized by the following features: 
     a) the first handling machine, which is arranged upstream of the reservoir in the conveying path of the articles, and/or the second handling machine, which is arranged downstream of the reservoir, can be controlled in terms of the operating speed (cycle speed) in accordance with the filling level of the reservoir, said level being measured constantly or from time to time, 
     b) the first handling machine, which is arranged upstream of the reservoir, can be driven at a higher output (cycle speed) when the filling level of the reservoir is comparatively low and can be driven at a correspondingly lower output (cycle speed) when the filling level of the reservoir is higher, 
     c) the second handling machine, which is arranged downstream of the reservoir, can be driven at a lower output (cycle speed) when the filling level of the reservoir is lower and can be driven at a higher output (cycle speed) when the filling level of the reservoir is higher. 
     The invention is based on the idea of carrying out a constant, continuously or cyclically carried out co-ordination of the handling machines with one another with the aid of the reservoir or of the filling level of the articles in the reservoir. Furthermore, the invention is based on the finding that the operation of one handling machine has to be co-ordinated constantly or from time to time with the operation of the other, associated handling machine, in order to achieve, in terms of the system as a whole, optimum machine functioning with the smallest possible number of machine stops. The aim of the invention is to reduce the number of times individual machines, or even the system as a whole, are/is switched off and, instead, to operate the same in a co-ordinated manner, if required, with reduced output. 
     As reference variable for the control of the machines, use is made, according to a further feature of the invention, of an optimum filling level of the reservoir, namely an average filling level of from 40% to 60% of the maximum capacity, preferably of 50%. Deviations from this optimum filling level of the store results in a change in output of one handling machine or the other. 
     According to a further feature of the invention, the co-ordination, controlled via the filling level of the reservoir, of the handling machines with one another is such that the individual, current output capacity of the relevant handling machines can be taken into account. For this purpose, the handling machines and the reservoir are connected to an Industrial Personal Computer (IPC) which processes the current filling level of the store with the operating data of the machines, to be precise in accordance with a predetermined, changeable configuration. By virtue of a programming unit which can be connected to the IPC, the set configuration can be changed and adapted to the respectively current conditions. For this purpose, it is possible, for example, for a laptop to be connected to the IPC via a serial interface. 
     The process according to the invention can be used particularly advantageously in the cigarette industry. In this case, the first handling machine, which is arranged upstream of the reservoir, is a maker for cigarettes. The downstream, second handling machine is a (first) packaging machine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Further details of the apparatus and process according to the invention are explained in more detail hereinbelow with reference to exemplary embodiments and/or use examples, in which: 
     FIG. 1 shows a schematic illustration of a system with central control unit, 
     FIG. 2 shows a block diagram for the control of handling machines in dependence on the filling level of a reservoir, 
     FIG. 3 shows, in the form of a graphic illustration, an exemplary embodiment for a configuration for controlling the handling machines, and 
     FIG. 4 shows an illustration analogous to FIG. 3 for a further-developed embodiment of the configuration. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The details explained with reference to the drawings relate to a preferred use example, namely a system used in cigarette technology. More precisely, the invention relates to a cigarette production machine, namely a maker  10 , being linked up to a (first) packer  11  for the cigarettes or for a formed cigarette group. The maker  10  is designed for a comparatively high output of, for example, up to 14,000 cigarettes per minute. The output capacity of the packer  11  is adapted to that of the maker  10 . For example, the output of the packer  11  may be around 700 packs per minute. This is the case with a packer  11  of known construction for the purpose of producing hinge-lid boxes or hinge-lid packs. 
     A store or reservoir  12  for the cigarettes is incorporated in the conveying path of the cigarettes from the maker  10  to the packer  11 . This store or reservoir is an apparatus of known construction. The reservoir  12  is designed for receiving a relatively large number of cigarettes. The cigarettes coming from the maker  10  are fed, via cigarette conveyors, to the reservoir  12  or directly to the packer  11 . 
     The operating speeds (rotation speed or cycle speed) of the maker  10  and of the packer  11  are set with respect to one another constantly or from time to time by co-ordinated control. If the output of one machine or the other is temporarily reduced, the operating speed of the respectively other machine is correspondingly changed, namely reduced. This reduces the number of stops of an individual machine or of the system as a whole. The control of the two machines, namely of the maker  10  and of the packer  11 , is effected via the filling level of the reservoir  12 . The latter is monitored constantly or cyclically by suitable means. 
     The sub-assemblies of the system described, namely the maker  10 , the packer  11  and reservoir  12 , are connected to a common control unit, in the present case to an Industrial Personal Computer, that is to say an IPC  13 . A control program which is geared to the respective application is stored in said IPC. The IPC  13  receives signals relating to the filling level of the reservoir via a control line  14 . In accordance with the control program, control signals for the maker  10  and packer  11  are derived therefrom and fed to these machines via control lines  15 ,  16 . 
     The control program stored in the IPC  13  may likewise be changed, namely adapted, for adaptation to current conditions or to changes in the controlled machines. For this purpose, a programming unit which can be connected to the IPC  13 , for example a laptop  17 , is provided. This unit can be connected to the IPC via a serial interface. The laptop  17  is suitable for diagnosis of the respective control program and for changing the parameters or the control algorithm. The changes or specified values for the algorithm are input into the laptop and transmitted from the latter to the IPC  13  as new parameters. The laptop may subsequently be withdrawn. The IPC  13  then carries out the speed control independently. 
     As can be seen from FIG. 2, in the case of this exemplary embodiment of the control algorithm, the IPC  13  has three interfaces. A first interface relates to the filling level of the reservoir  12 . This supplies signals relating to the current filling level to the IPC  13 . The filling level is transmitted, for example, via an Ethernet interface. 
     The second interface relates to the specified rotational-speed value of the packer  11 . The specified rotational-speed value calculated in accordance with the control algorithm is transmitted from the IPC  13  to the packer  11  via a four-bit BCD, 24V digital interface. 
     In the same way, the specified rotational-speed value is transmitted from the IPC  13  to the maker  10  via the third interface, to be precise likewise via a four-bit BCD, 24V digital interface. 
     In the case of the illustrated, preferred exemplary embodiment of a system for cigarettes, a standard connection remains between the reservoir  12 , on the one hand, and the maker  10  and packer  11 , on the other hand. So-called status signals are exchanged between these sub-assemblies of the system via control connections  18 , on the one hand, and  19 , on the other hand. These signals are, for example, signals for an “emergency stop”, that is to say for switching off one sub-assembly or the other, for a changeover to “standby”, etc. 
     In the case of an advantageous embodiment of the control system, the transmission of the signals from the IPC  13  to the maker  10  and packer  11  is provided with an additional bit as “sign of life”. As long as this sign of life is active, the specified rotational-speed values and/or control signals coming from the IPC  13  take effect at the maker  10  and packer  11 . If no activity is established at the interfaces to the IPC  13  by the maker  10  and packer  11 , these machines, that is to say the maker  10  and/or packer  11 , continue with the specified speed values which are transmitted via the control connections  18  and  19 , that is to say in accordance with a predetermined standard program. 
     The control signals of the IPC  13  are transmitted via four-bit BCDs. This results in  16  available speed stages. Which bits are used for the specified speed values depends on the possible speed stages of the corresponding machine—maker  10  or packer  11 . 
     The specified rotational-speed values, that is to say the control signals of the IPC  13 , are checked at short time intervals, for example at intervals of  4  seconds. These specified values are updated in this way. 
     FIG. 3 is a graphic illustration of a first embodiment of the configuration for the control of the maker  10  and packer  11 . In a set of co-ordinate axes, the rotational speeds or output assigned to the packer  11 , to be precise in accordance with the number of packs produced per minute (p/min), is plotted on the horizontal branch  20 , which points to the right. A branch  21 , which runs in the opposite direction, gives the respective output of the maker  10 , that is to say the rotational speed of the same, expressed in number of cigarettes per minute (c/min.). A vertical line  22  is the filling level of the reservoir  12 . The measurements and speeds start from a common zero point  23 . 
     A bottom line  24  marks a minimum filling level of the reservoir  12  of, for example, 10%. If the filling level drops below this amount, the maker  10  or the packer  11  is switched off. 
     In the region of the minimum filling level according to line  24 , the packer  11  is operated at a minimum output of, for example 250 p/min, corresponding to vertical line  25 . When the filling level of the reservoir  12  rises, the output or cycle or rotational speed of the packer  11  rises (in linear fashion) along the line  26 . The configuration is such that, in the present case, when the filling level of the reservoir  12  is at an optimum level of 50%, corresponding to the line  27 , the maximum output of the packer  11  has been reached, corresponding to the vertical line  28 , at for example 700 p/min. This output, as can be gathered from an output line  29 , is maintained when the filling level of the reservoir  12  increases further. 
     In the same way, the maker  10  is controlled in accordance with the filling level in the reservoir  12 . When there is a maximum critical filling level of, for example, 90%, corresponding to the line  30 , the maker  10  is switched off in order to prevent the continued feed of cigarettes to the reservoir  12 . Starting from the line  30 , corresponding to this maximum filling level, the maker, when there is a reduction in the filling level, begins with the production and feed of cigarettes corresponding to line  31 , which may correspond to an output of, for example, 10,000 c/min. When the filling level in the reservoir  12  is reduced further, the output of the maker  10  rises gradually corresponding to line  32  to a predetermined maximum output of, for example, 14,000 c/min, marked by line  33 . This maximum output is also maintained when the filling level in the reservoir  12  is reduced further. 
     The graphic illustration according to FIG. 4 is based on a more complex configuration for the control of the maker  10  and packer  11 . The lines which correspond to the illustration according to FIG. 3 have been carried over. As can be seen, the rise in the output of the packer  11 —starting from a critical minimum filling level according to line  24 —begins at a higher rotational speed or output, corresponding to line  34 . This corresponds, for example, to an output of 400 or 500 p/min. The rise in the output is selected such that even at a filling level below the optimum filling level, corresponding to line  27 , the maximum output of the packer  11  has been reached, namely at a line  35 , which may correspond to a filling level of, for example, 30% or 35% of the reservoir  12 . This configuration is based on the finding that, when the filling level in the reservoir  12  rises, it is expedient to have a higher output and for the maximum output to be reached more quickly in the case of the packer  11 . 
     In the opposite direction, namely when the filling level in the reservoir  12  falls, at the line  36 , that is to say above the optimum filling level according to line  27 , for example at 60% or 70% filling level in the reservoir  12 , the output of the packer  11  is reduced and, corresponding to the line  37 , brought down to a minimum output, corresponding to vertical line  25 . In this case, this minimum output is achieved at approximately 25%, corresponding to line  38 . A further reduction in the output is not envisaged. 
     The maker  10  is operated in the same way in accordance with this configuration. When the filling level of the reservoir  12  tends to fall, the maker  10  is controlled corresponding to line  38 . This means that when the filling level drops below the critical maximum filling, corresponding to line  30 , the maker  10  resumes the production operation at an output of, for example, 12,000 c/min corresponding to line  39 . The maximum output, corresponding to line  33 , is achieved more quickly, namely still above the optimum filling level, corresponding to line  27  (50%). 
     Conversely, when a rise in the filling level in the reservoir  12  is established, the maker  10 , starting from a minimum filling, below the optimum filling level—line  27 —is changed over to reduced output, namely at approximately 30% filling level, corresponding to the line  39 . Starting from here, the maker  10  is brought back, in terms of the output, to the minimum output, corresponding to line  31 , at for example 10,000 c/min. 
     Other configurations are possible if required and can be input into the control unit or into the IPC  13  in the manner described. There is thus no need for a linear, that is to say straight-line, progression of the changes in output of the maker  10 , on the one hand, and the packer  11 , on the other hand, in the case of the exemplary embodiment of FIG. 4, within the region delimited by the obliquely running lines. Rather, it is possible to introduce a further dependency, which can be gathered, in principle, from the block diagram of FIG.  2 . In accordance with this, it is possible, within the surface areas  39  and  40  marked in FIG. 4, to have an arcuate or even irregular progression of the rising or falling lines of the outputs of the maker  10  or packer  11 , depending on the configuration stored in the IPC  13 . 
     The block diagram according to FIG. 2 illustrates the control concept of the apparatus according to the invention. The rotational speeds of the maker n m-des  and of the packer n p-des  are controlled or regulated on the basis of the filling level of the reservoir f r . In this case, the procedure is as follows: 
     For the controlled rotational speed of the maker n m-des , the current filling level of the reservoir f r  is measured and calculated along with a predetermined desired filling level f r  of the same. The difference between these two variables is formed for this purpose. This difference is multiplied by a first constant, namely a control parameter or a static factor k m1 . This gives a proportional component of the control algorithm. In parallel with this, the measured filling level of the reservoir f r  is differentiated and multiplied by a second constant, namely the control parameter or a dynamic factor k n2 . This gives the differential component of the control algorithm. The proportional component and the differential component are then calculated along with the maximum rotational speed of the maker n m-max  to give the desired rotational speed n m-des  of the same. For this purpose, the proportional component is added to the maximum rotational speed of the maker, but the differential component is substracted therefrom. The control algorithm for the rotational speed of the maker n m-des  is expressed overall by the following formula:          n     m   -   des       =       n     m   -   max       +       k   m1     *     (       s   r     -     f   r       )       -       k   m2     *     (            (     f   r     )            t       )                                
     The procedure is the same for the control of the rotational speed of the packer n p-des . Starting from the current filling level of the reservoir f r , a proportional component k p1 *(f r −s r ) and a differential component          k   p2     *     (            (     f   r     )            t       )                            
     of the control algorithm for the rotational speed of the packer n p-des  are calculated. The proportional component and differential component are then calculated along with the maximum rotational speed n p-max  for the packer. This is done using the following formula:          n     p   -   des       =       n     p   -   max       +       k   p1     *     (       f   r     -     s   r       )       +       k   p2     *     (            (     f   r     )            t       )                                
     Accordingly, overall, both the rotational speed of the maker n m-des  and the rotational speed of the packer n p-des  are calculated in accordance with a proportional-differential control algorithm. 
     List of Designations 
       10  Maker 
       11  Packer 
       12  Reservoir 
       13  IPC 
       14  Control line 
       15  Control line 
       16  Control line 
       17  Laptop 
       18  Control connection 
       19  Control connection 
       20  Branch 
       21  Branch 
       22  Line 
       23  Zero point 
       24  Line 
       25  Vertical line 
       26  Line 
       27  Line 
       28  Vertical line 
       29  Output line 
       30  Line 
       31  Line 
       32  Line 
       33  Line 
       34  Line 
       35  Line 
       36  Line 
       37  Line 
       38  Line 
       39  Surface area 
       40  Surface area