Method for controlling a blister packaging machine

The invention relates to a method for controlling a blister packaging machine, which has at least one working station operating in a clockwise manner, during which at least one first adjustment movement takes place during a period T_V1 , A subsequent treatment state in which a treatment of a product and / or material takes place over a period T_B , Then a second adjustment movement over a period T_V2 And, if appropriate, a rest state over a period T_R The periods T_V1, T_B, T_V2 and T_R And a resulting clock rate R (= cycles / min) of the packaging machine are preset, and at least the clock rate R is converted by means of an input device to a changed clock rate R_V Is alterable.

A blister packaging machine of conventional construction comprises a molding station in which a plurality of cup-shaped depressions are formed into a base film made of plastic or aluminum, into which a product, for example a pharmaceutical tablet, is inserted in a downstream filling station. After the product feed, the bottom film is fed to a sealing station. Immediately before or inside the sealing station, a cover film is fed and placed on the base film. The cover film is sealed tightly on the bottom film by heat action within the sealing station, whereby the product is enclosed in the cup-shaped depression.

The forming station is operated in a tact-wise manner and thus discontinuously. The sealing station can either be operated in a clockwise manner, alternatively it is also known to operate the sealing station continuously, the transition from the tact operation of the forming station to the continuous operation of the sealing station being effected by means of known compensating devices.

Document US 4875329 discloses a method for controlling a blister packaging machine having multiple synchronized work stations.

The performance of a blister packaging machine depends essentially on the clock rate R, ie the number of clocks to be executed per minute. From the clock rate R, the clock time T which is maximally available for a working clock is obtained_Max In milliseconds to T_Max = 60,000 / R [ms], ie, at a clock rate R of 75 clocks / min, the maximum clock time T is_Max = 800 ms. A clock curve of a corresponding work cycle is shown as a simplified polygonal path-time diagram in FIG. 2, which is briefly explained below.

Within the maximum cycle time T_Max The tactically operated forming station, from which the following is to be exemplified, must carry out various movements and treatments or treatments. Starting from a basic or zero position at the beginning of the cycle (point 0 in FIG. 2), in which two mold plates between which the bottom film to be deformed extends completely, a first adjusting movement, namely the closing movement of the mold plates, is carried out . The closing path S_V Is predetermined by production technology and the closing movement is carried out over a predetermined period of time T_V1 Is carried out until the point 1 (see FIG. 2) is reached in which the mold plates are closed and have reached their end position.

The mold plates have then reached their treatment state, in which, for example, a preheated plastic bottom film is applied over a period T_B Wherein the cap-shaped depressions are additionally formed in the base film, in particular by means of compressed air or molding punches. At point 2 of the clock curve, the cooling or treatment of the bottom film is terminated and a second adjusting movement follows, namely the opening movement of the mold plates, which in turn is effected via the path S_V (But in the opposite direction) over a period T_V2 Respectively. At the end of the opening movement, ie, at point 3 of the clock curve, the initial position is again reached. The opened mold plates can then be removed for a period T_R In a resting state. The duration of the period T_R Of the resting state largely depends on influences outside the molding station and can, in the best case, be very short or even 0.

As soon as the mold plates are opened by a sufficient amount, the transport of the bottom film can be initiated and carried out. According to FIG. 2, it is assumed, for example, that the transport of the floor film begins when the mold plates travel around the path S_V/ 2, ie, there is a time span t for the transport of the bottom sheet to the end of the stroke_Z1 And from the beginning of the next cycle until the time when the mold plates are again half-closed, a period t_Z2 , Wherein a total transport time Tz is obtained from the sum of t_Z1 and t_Z2 Respectively.

In earlier blister packaging machines, the curve trajectories were mechanically determined by rotating cam disks, the rotational movement of which was derived from a central, driven main shaft, the so-called king shaft. In modern blister packaging machines, the curves are stored by software and the motorized drive of the adjustment movements is effected by means of servomotors, which are addressed by a control electronics or the corresponding software.

When a blister packaging machine is set up to a particular blister format, the movement sections of the clock curve are usually designed in such a way that they meet the process requirements as much as possible and can still be executed with the highest possible clock rate. In this case, the individual steps of the clock are to be executed with high reliability and safety, and a high efficiency, ie a high performance, of the packaging machine is to be achieved. The determined format-specific process data are stored. If the blister packaging machine is to process blisters of the same format at a later time, the stored data are retrieved and the packaging machine is operated accordingly. This approach is based on the theoretical idea that the same blister format can always be optimally processed with the same, stored process parameters.

In practice, however, it has been found that during operation of the blister packaging machine, which is part of a larger packaging system, unexpected problems can occur which can reduce the efficiency of the packaging installation. These problems can be caused by disturbances of individual stations of the blister packaging machine or also by disturbances or problems of upstream or downstream plants, for example in a downstream cartoning machine. In the cartoner, fluctuations in the brochure material or in the folding box material can occur, whereby the preset, relatively high clock rate can not be maintained. In addition, there may be clock problems in subsequent machines, for example in the case of a bundle packer, or product fluctuations which adversely affect the speed of the product feed in the blister packaging machine. In addition, it may be possible that, for reasons of illness and / or leave, for example, insufficient staff is available at the entire packaging plant, so that this must be reduced in its processing speed.

Since the mentioned problems and faults can not always be repaired or repaired at short notice, it is customary to continue the blister packaging machine with an increased reject rate or a reduced packaging quality, or if this is not acceptable, the plant is stopped until the fault is corrected Is.

In terms of control technology, it would also be possible to reduce the cycle rate of the blister packaging machine and possibly other machines of the packaging line. However, the molding and sealing parameters could be changed so strongly by this measure that a perfect shaping and sealing process is no longer ensured.

In the following, it will be assumed, for example, that the blister packaging machine can not be operated with the originally preset maximum clock rate R of, for example, 75 clocks per minute, since the tablets have changed slightly in their dimensions and thereby slowed somewhat through the feed channels of the Fill station. If the clock speed was unchanged, the proportion of blisters which were incompletely filled would increase sharply. Problems in other machines of the packaging line may also necessitate a reduction in the clock rate.

If the clock rate R is used to avoid an increased proportion of defectively filled blisters to a changed clock rate R_V , A higher maximum clock time T is obtained for each clock pulse_Max. It is assumed that the clock rate R of 75 clocks per minute changes to a changed clock rate R_V Of 50 cycles per minute, so that a new maximum cycle time T_Max = 60,000 / 50 = 1,200 (ms). In a conventional blister packaging machine, the stored clock curve is maintained in its basic course, but all the time periods T_V1, T_B, T_V2 and T_R By a factor of 1,200 / 800 = 1.5. A correspondingly stretched clock curve is shown in FIG. From this it can be seen that the duration T_B Of the treatment, eg of a mold and cooling process of the floor film, is increased by 50%. In addition, the duration of the first and second adjustment movements are lengthened in such a stretched clock curve, which in turn can lead to a reduction in the preferred speed and thus lead to a longer cooling time of the preheated base film during the transport time. By changing the process parameters, defective or incompletely formed wells can arise.

The invention is based on the object of providing a method for controlling a blister packaging machine in which the clock rate can be arbitrarily varied within predetermined limits in the production phase without problems in the packaging process and in particular in the case of forming the bottom film or in sealing the film Cover film.

This object is achieved according to the invention by a method with the characterizing features of claim 1. In this case, it is provided that an error resulting from the changed clock rate R_V Is the difference between the duration T.sub.T_R Of the rest state.

When the clock rate R changes to the changed clock rate R_V , A time gain with respect to the maximum clock time T is obtained_Max Or a clock time difference .DELTA.T, which is 400 ms (= 1,200 ms - 800 ms) in the example described above. The invention is based on the basic idea of ​​not dividing this clock time difference ΔT uniformly over all curve sections of the clock curve, ie, compressing or expanding the clock curve in a known manner, but rather the clock time difference ΔT substantially or even completely for changing the duration T_R Of the rest state. In this way, the essential process parameters, namely the duration T_V1 The 1st adjustment movement, the duration T_B The treatment condition and the duration T_V2 Of the second adjustment movement are kept within narrow limits which are favorable for the process sequence. In a preferred embodiment of the invention, the aforementioned periods T_V1, T_B and T_V2 When entering a changed clock rate R_V And thus the cycle time difference .DELTA.T is completely changed to the duration T.sub.T._R Of the rest state.

The working station, whose clock curve is changed during a change in the clock rate, can be the forming station of a blister packaging machine. The molding station has two mold plates which are adjustable relative to one another and between which a bottom sheet is provided with cup-shaped receptacles. If the bottom sheet is made of plastic, it is processed in a preheated state and cooled in the molding station. The first adjusting movement is then formed by the closing movement of the mold plates, wherein the closing movement is not completed until the end position of the mold plates has been reached, and the mold plates can already be in contact with one another in the last movement phase of the closing movement. At the end of the closing movement, the mold plates remain for a period T_B In a treatment state in which the bottom film is reformed and, if necessary, cooled. The second adjusting movement is then the opening movement of the mold plates, which return to their open initial position. Subsequently, the mold plates remain for a period T_R In its open position. If the clock time difference .DELTA.T obtained by the reduction of the clock rate is completely equal to the change in the duration T.sub._R Of the resting state and the temperature of the preheated film remains unchanged, the actual treatment of the bottom film does not change in the molding station of the blister packaging machine, and also the molding plates are moved at the preset speed. A reduction in the clock rate merely results in the mold plates remaining in their open position for an extended period of time at the end of the cycle. Maintaining the periods T_V1, T_B and T_V2 Leads to the constant retention of the process-relevant size of the forming time. In this way, a good deformation of the bottom sheet is achieved, while at the same time high process reliability.

Alternatively, it is also possible for the working station to be a sealing station with sealing plates which can be adjusted relative to one another, between which a cover film is sealed onto the bottom film. In this case, the first adjusting movement is the closing movement of the sealing plates which, at the end of the closing movement,_B Remain in a treatment state in which the sealing of the covering film to the bottom film takes place. The second adjusting movement is the opening movement of the sealing plates, wherein the sealing plates, after reaching their open position in the latter,_R remain. In this case, keeping the periods T_V1, T_B and T_V2 To maintain the process-relevant size of the sealing time.

The desired changed clock rate R_V (= Clocks per minute) is preferably input directly by means of the input device, wherein a processing unit from the inputted changed clock rate R_V The maximum available clock time T_Max = 1 / R [min] = 60,000 / R [ms].

In a preferred embodiment of the invention, it is provided that the changed clock rate R_V Can not assume any desired value and, in particular, can not become excessively small. It is, therefore, provided that one of the preset clock rate R and the changed clock rate R_V To a limit ΔR_G Is limited. The limit value ΔR_G Can be in the range of 20% to 30% of the preset clock rate R and is preferably 25% of the preset clock rate R.

Further details and features of the invention can be gathered from the following description of an exemplary embodiment with reference to the attached drawing. Show it:<dl id="dl0001"><dt>FIG</dt><dd>A schematic representation of the essential components of a blister packaging machine,</dd><dt>FIG</dt><dd>A typical clock curve as a path-time diagram in a simplified representation,</dd><dt>FIG</dt><dd>The clock curve which is elongated by a factor of 1.5 according to FIG. 2,</dd><dt>FIG</dt><dd>A clock curve modified according to the invention; and FIG</dd><dt>FIG</dt><dd>12 is a schematic plan view of an input device.</dd></dl>

FIG. 1 shows the essential components of a blister packaging machine 10 in a schematic representation. A bottom sheet 11 made of plastic is fed to a heating station 12 which has a lower heating plate 12b and an upper heating plate 12a which is adjustable relative to the lower heating plate 12b. When the two heating plates 12a and 12b are closed, the bottom film received between them is heated.

Directly to the heating station 12 is a molding station 13, which comprises a lower mold plate 13a and an upper mold plate 13b which is adjustable therefor. The two mold plates 13a and 13b, which are shown in the open position, can be closed, the bottom film accommodated between the closed mold plates 13a and 13b being cooled and simultaneously provided with cup-shaped depressions by supplying compressed air or by means of shaping punches. Connected to the molding station 13 is a transport device 14, by means of which the bottom film 11 is pulled by the individual stations in a clock-wise manner.

The bottom sheet 11 provided with the cup-like depressions is then fed via deflecting rollers 15 and 16 to a filling station 17 in which a product, for example a pharmaceutical tablet, is inserted into each depression. The bottom sheet 11 then passes to a sealing station 20. Immediately in front of the sealing station 20, a cover sheet 18 is placed on the bottom sheet 11 via a deflecting roller 19. In the sealing station 20, which comprises a lower sealing plate 20b and an upper sealing plate 20a, the cover film 18 is sealed onto the base film 11 by closing the warm sealing plates 20a and 20b and the heat acting on the films. The sealing station 20 is followed by a further transport device 21 which is synchronized in its movement with the transport device 14 and ensures a tactile transport of the film composite provided after the sealing station 20.

FIG. 2 shows the simplified path-time diagram of a clock curve, which has already been explained, for example the molding station 13. The maximum clock time T_Max Is 800 ms, which corresponds to a clock rate R of 75 clocks per minute. Starting from the open basic position of the two mold plates 13a and 13b, these are heated within a period T_V1 Closed, while the closing path S_V return. As soon as the mold plates 13a, 13b have reached the end position of their closing movement (point 1 of the curve in FIG. 2), the treatment state begins, which extends over a period T_B Respectively. During the treatment condition, the bottom film is provided with cup-shaped depressions. If the bottom sheet is made of plastic, it is additionally cooled. At point 2 of the curve, the treatment state is terminated and the opening of the mold plates 13a and 13b which, in turn, travels along path S_V In the opposite direction to the closing movement and over a period T_V2 Respectively. At the end of the opening movement at point 3 of the curve, the open starting position of the mold plates 13a and 13b is again reached in which they are in a rest state for a time period T.sub.1_R Persist until the next bar begins.

It was assumed in FIG. 2 that the transport of the film begins or ends with half-opened mold plates 13a and 13b, so that a total transport time T_Z = t_Z1 + t_Z2 Respectively.

If the user determines that this total transport time T_Z Is not sufficient, it can lower the preset clock rate R. To this end, the user outputs a reduced clock rate R_V (= Clocks per minute), so that the maximum available clock time T_Max = 60,000 / R_V [Ms] is determined. It is assumed, for example, that the user selects the clock rate R_V To 60 clocks per minute, which corresponds to a changed maximum clock time T_max = 1,000 ms.

In the case of a change or a reduction in the clock rate, the process parameters for the closing movement of the mold plates, for the treatment state and for the opening movement of the mold plates are kept so that the clock curve between the points 1 and 3 does not change as shown in FIG . However, since the clock rate R_V To 60 cycles per minute and thus the maximum cycle time T_max To 1000 ms, is the opposite of the original clock rate R at the changed, reduced clock rate R_V A clock time difference .DELTA.T of 200 ms, which is completely assigned to the idle state, so that the mold plates for a longer period of time T_RV In their fully open position. As shown in FIG. 4, the transport time T is also in this way_ZV Of the films is substantially lengthened so that the transport speed of the films can be adjusted to a value adapted to the film material.

As shown in FIG. 5, the input device 30 is assigned a processing unit 40, which is composed of the input value for the changed clock rate R_V The corresponding clock curve is determined and in particular checks whether the inputted value of the clock rate lies within predetermined limits.