Film slip monitoring and packaging machine with film slip monitoring

Abstract

The invention relates to a method for monitoring a film feed of a top film (3) used for sealing packaging bases (T) fed by a sealing tool (5) of a packaging machine, which is carried out intermittently by means of a top film transport device (2), wherein it is checked whether the top film (3) is moved in the pull-off direction (R) according to a preset target film pull-off length (L) during the film feed. The invention further relates to a packaging machine for checking a film feed.

Description

[0001] The present invention relates to a method for detecting a film feed on a packaging machine according to claim 1. Furthermore, the invention relates to a packaging machine with a film slip monitoring system according to claim 9.

[0002] Traditionally, the film feed of a top film on a tray sealing machine, also known as a "tray sealer," is achieved by a rubberized drive roller. It is assumed that the coefficient of friction between the rubber coating and the top film is sufficient to transport the top film without slippage. However, if the rubber coating of the drive roller wears down, for example due to hardening, the coefficient of friction decreases, which can cause the transported top film to slip, thus compromising the safe and precise positioning of the top film.If the position of the top film, in particular the actual film pull-off length, deviates significantly from a target position achieved by the film feed, especially from a predetermined target film pull-off length, this can even lead to a situation where, due to such a slippage-prone, faulty film feed movement, a cut-out in the top film produced at the last position of a film grid by a sealing tool of the packaging machine is not pulled far enough out of the sealing tool. As a result, the last cut-out in the film grid can at least partially lie on a package within the sealing tool, meaning the cut-out is not outside the package. Consequently, this package is not completely sealed with the top film in the subsequent sealing operation.In the event that such incompletely sealed packages are further fitted with a lid or covering, for example a label, later in the production line, detection of the area left open due to the insufficient film feed is not possible or only with great difficulty.

[0003] The object of the invention is to provide an improved method and an improved packaging machine with regard to the problem previously described in connection with the prior art, in order to better ensure the production of completely sealed packaging.

[0004] This problem is solved by means of a method according to claim 1. Furthermore, the problem is solved by a packaging machine according to claim 9.

[0005] Advantageous further developments of the invention are given by the respective subject matter of the dependent claims.

[0006] The present invention relates to a method for monitoring the film feed of a top film, used for sealing packaging bases fed by a sealing tool of a packaging machine, which is carried out intermittently by means of a top film transport device. A characteristic feature of the invention is that it is checked whether, during the film feed, the top film is moved in the pull-off direction according to a preset target film pull-off length. For this check, a measuring system of the top film transport device is used in particular.

[0007] In contrast to a conventional solution, which assumes that sufficient friction between the top film and a rubberized drive roller is enough for precise film feed, the invention verifies, i.e., measures, whether the top film has been moved in the pull-off direction according to the preset target film pull-off length during film feed. This measurement with regard to the target film pull-off length can be carried out using simple, integrated measuring devices. If the measurement or verification shows that the top film has not been moved according to the desired target film pull-off length, this indicates that the top film is slipping at some point along the top film transport device, for example, at a rubberized drive roller used for transporting the top film.

[0008] In particular, several film feed movements, i.e., the actual recorded film pull-off length, can be compared with each other in order to detect a gradual deterioration of the film positioning due to a gradually increasing film slippage.

[0009] The metrological verification according to the invention on the upper film transport device, which in particular allows the determination of whether and to what extent the actual film pull-off length deviates from the target film pull-off length during film feed, can be implemented cost-effectively on the packaging machine. Furthermore, this verification enables a rapid machine stop to prevent defective packaging. Moreover, the metrological verification according to the invention can be used as the basis for dynamic control, allowing the machine to approach the desired target film pull-off length immediately during the same film feed or at least during the next film feed, if a deviation of the actual film pull-off length from the target film pull-off length is detected.

[0010] Based on the inventive inspection and monitoring of the film feed, film slippage, which may lead to incompletely sealed packaging, can be determined. In particular, the inventive method can be effectively used to detect at an early stage whether the coefficient of friction of a drive roller used for peeling off the top film, for example, the coefficient of friction of a rubberized drive roller, is decreasing. If so, the rubber coating itself, or the rubberized drive roller including the entire rubber coating, can be replaced quickly, so that the desired, preset target film peel length per film feed can again be achieved.

[0011] One advantageous variant involves checking, for each film feed, whether the top film moves in the take-off direction according to the preset target film take-off length. This makes it possible to extend slip monitoring to all feed movements, thus enabling early detection of slippage.

[0012] Alternatively, the slip check could be performed only every second feed cycle. A conceivable scenario would be one in which the slip check is performed three out of four, particularly four out of five, particularly five out of six, particularly six out of seven, particularly seven out of eight, particularly eight out of nine, particularly nine out of ten feed cycles.

[0013] Preferably, for each film feed in the pull-off direction, at least one measurement is taken behind the sealing tool to detect the area of ​​the top film following a film grid pulled out of the sealing tool, in the track width, i.e., a width transverse to the pull-off direction, of the last cut-out of the film grid. This allows it to be determined whether the cut-out produced last in the film grid has been pulled sufficiently far out of the sealing tool. If the area of ​​the top film following the last cut-out can be detected by the sensor, it can be ruled out that the last cut-out of the film grid has come to rest on the packaging positioned at the front in the sealing tool in the pull-off direction.In other words, the successful sensor detection of the top film section following the last cut indicates that the top film has been advanced sufficiently far by the film feeder, meaning that this film feed was carried out without slippage. Detecting the top film section in the take-off direction behind the last cut of the film grid thus provides sufficient verification as to whether the preset target film take-off length has been reached based on the top film feed.

[0014] According to one embodiment of the invention, the rotation angle of a rubberized deflection roller used for film feed in the top film transport device is measured for each film feed. A rubberized rotary encoder roller can be used for this purpose. This rubberized rotary encoder roller could, for example, be arranged on an inlet side of the sealing tool to deflect the top film unwound from a film holder, particularly towards a rubberized drive roller, which may interact with a counter-pressure roller to control the take-off of the top film. Alternatively or additionally, a rubberized rotary encoder roller could be assigned to a film rewinder on an outlet side of the sealing tool as a deflection roller or as a drive roller. A rubberized deflection roller configured for rotation angle detection can be inconspicuously integrated into the machine structure.Their rotation angle measurements, together with their diameter, yield a specific arc length, from which the peel length of the top film is determined.

[0015] It would be conceivable to implement the film feed using a rubberized drive roller positioned downstream of the rubberized rotary encoder roller in the pull-off direction, possibly using a rubberized drive roller with a counter-pressure roller. The rubberized drive roller could be positioned either as a separate drive roller on the infeed side of the sealing tool or on the outfeed side of the sealing tool in the area of ​​the residual film winder, in order to pull the top film through the sealing tool. Such a drive roller could be controlled with a predetermined rotation angle for each film feed, with the aim of achieving the target film pull-off length.

[0016] A preferred variant provides that the rubberized deflection roller configured for angle detection, or the rubberized rotary encoder roller, serves as the drive roller to move the top film in the take-off direction, particularly when no separate rotary encoder deflection roller is used. The angle of rotation of the drive roller could be detected by a sensor used to control the drive roller. In particular, the drive roller could be positioned at the inlet or outlet of the sealing tool. It would also be conceivable to use several such drive rollers along the top film transport device, for example, one at the inlet of the sealing tool and another at the outlet, at least one of which is equipped with an angle detector.

[0017] One approach involves measuring the rotation angle of a film roll holder used to support a film roll for each film feed. This rotation angle can then be used to calculate the actual film pull-off length, for example, by taking into account the film roll diameter, which tends to decrease with each film feed.

[0018] Slip detection could be achieved, in particular, by comparing the rotation angle measured at the film reel mandrel with the rotation angle of the drive roller. In this approach, it would be conceivable that the rotation angle could be measured using an existing sensor on a servo motor used to rotate the film reel mandrel. Alternatively, the film reel mandrel could be configured as a rotary encoder to measure its rotation angle for each film feed. If the measured rotation angle of the film reel mandrel decreases too much or does not increase quickly enough, this indicates that the top film is slipping on the drive roller, meaning the film feed is subject to slippage.

[0019] Preferably, the diameter of a film roll mounted on the top film transport device is measured for each film feed. As the top film is pulled away, the film roll diameter decreases continuously. This results in a continuous increase in the number of revolutions or the rotation angle of the film roll mandrel. At least one ultrasonic sensor is used to measure the decreasing film roll diameter for each film feed. Based on this measurement, and especially in conjunction with the measured rotation angle of the film mandrel, the actual film pull-off length can be determined. Preferably, the rotation angle of the film mandrel is measured using the existing sensors of a servo motor used to rotate the film mandrel.

[0020] At least one ultrasonic sensor can be positioned on the inlet side of the sealing tool in the area of ​​the film holder and is specifically directed at the film roll for continuous measurement of the film roll diameter. It would be conceivable for the film roll diameter measurement to occur intermittently, so that when the film feed movement stops, the corresponding film roll diameter is recorded and this can be factored into the calculation of the actual film pull-off length based on the underlying rotation angle of the film holder mandrel.

[0021] According to one embodiment, the rotation angle of a drive shaft of a servomotor used for film feeding is measured. This can be achieved using a separate rotary encoder or an encoder already integrated into the servomotor. This can be the rotation angle of a drive shaft of the film rewinder and / or the rotation angle of a drive roller of the film feeder.

[0022] Preferably, a closed-loop control system dynamically controls the film feed. Specifically, this involves continuously monitoring whether the top film pull-off direction is moving according to the preset target film pull-off length, enabling dynamic control of the film feed in real time. This could be achieved by dynamically controlling the tension acting on the transported top film and / or the pull-off torque of the film holder. This can be accomplished, for example, by repositioning the film reel mandrel, the drive roller, and / or the rubberized encoder roller.

[0023] According to an advantageous embodiment of the invention, the upper film transport device dynamically reacts to film slippage detected by a target / actual film take-off length comparison during film feed. This allows for a correction to be made during the film feed so that the film feed in the take-off direction still reaches the desired length. Following the correction, the machine's operation can be interrupted or at least a warning message can be sent to the operator.

[0024] One practical approach involves issuing a film slippage warning message when the deviation reaches a preset initial threshold. This makes it possible to alert the operator to a film feed that is subject to slippage but still within tolerance, allowing them to take appropriate countermeasures or at least be warned that further increases in slippage will lead to defective packaging, i.e., packages that are not completely sealed.

[0025] In particular, the packaging machine is stopped when the detected deviation reaches a preset second threshold that is higher than the first. This allows for the detection of slippage that is no longer within tolerance and leads to defective production.

[0026] It would be conceivable to use a measuring device along the top film transport system. Based on its measurements, the coefficient of thermal expansion of the top film could be determined, which would then be used as a correction factor when measuring the actual film pull-off length. For example, a measuring device could integrate an ultrasonic sensor for measuring the film diameter and a sensor for measuring the temperature of the top film into a single housing. A thermal imaging camera or an infrared sensor could be used, for instance, to measure the temperature of the top film.

[0027] The invention further relates to a packaging machine, which is particularly designed in the form of a tray sealing machine. The packaging machine according to the invention comprises a sealing station with a sealing tool for receiving packaging bases and a top film transport device for transporting a top film through the sealing tool in order to seal the packaging bases received therein by means of the top film. According to the invention, the top film transport device is configured to check whether the top film has advanced in the pull-off direction according to a preset target film pull-off length during a film feed. A measuring system of the top film transport device can be used for this purpose.

[0028] The top film transport device according to the invention can detect film slippage, which occurs when the top film is not transported far enough during the film feed. If the check to see whether the top film has advanced in the pull-off direction according to a preset target film pull-off length shows that this is not the case, then the actual film pull-off length during this underlying film feed movement is not sufficient to meet the target value. However, this may still be a film feed within tolerance, i.e., an acceptable deviation that indicates slippage but does not yet result in incompletely sealed packaging.If a film feed length that is outside the tolerance range is detected, the top film has not been pulled far enough out of the sealing tool. Therefore, it can be assumed that incompletely sealed packages will be produced in the subsequent sealing process. Conversely, checking the target film pull-off length may reveal that a proper film feed with sufficient length in the pull-off direction is present, provided the target film feed length is met or at least a film feed within tolerance is detected. This allows for the sealing of good packages and the subsequent film feed to continue with the same settings on the top film transport device.

[0029] According to one embodiment, the top film transport device is configured to check whether the top film has advanced in the take-off direction according to a preset target film take-off length for each film feed. This makes it possible to extend slip monitoring to all feed movements, thus enabling early detection of slippage.

[0030] Alternatively, it could be stipulated that the slip check can only be performed in every second feed cycle. A conceivable scenario would be one in which the slip check can be performed in three out of four, in particular in four out of five, in particular in five out of six, in particular in six out of seven, in particular in seven out of eight, in particular in eight out of nine, in particular in nine out of ten feed cycles.

[0031] One variant provides that, on the exit side of the sealing tool in the pull-off direction, at least one measuring device is arranged to detect a section of the top film following a cutout in the film grid being pulled out of the sealing tool. This section, along with a subsequent cutout, forms an intermediate rib in the top film material. If the measuring device, for example, at least one ultrasonic sensor, can detect the section of the top film material following the last cutout in the film grid, this is a reliable indication that the top film material has been moved sufficiently far by the film feed, i.e., according to the specified target film pull-off length or at least within a tolerance of this, so that it can be assumed that the packaging bases can be sealed all around with the top film in the sealing tool.

[0032] Preferably, the top film transport device has at least one rubberized deflection roller with a rotary encoder. A rubberized rotary encoder roller can be used for this purpose. This deflection roller can be positioned as a deflection roller on an inlet side and / or on an outlet side of the sealing station. On the inlet side of the sealing station, it can be mounted directly adjacent to the film intake, in particular to guide the unwound top film to a drive roller for the film feed. On the outlet side of the sealing station, the rubberized deflection roller, configured for rotation angle detection, can feed the film mesh material directly to the film rewinder.

[0033] According to one embodiment, the top film transport device has a rubberized drive roller. This roller can be equipped with a counter-pressure roller, so that the top film is guided between them. The drive roller can be mounted at the outlet of the sealing station to pull the top film through the sealing tool. In particular, the drive roller serves to feed the film grid to a film rewinder at the outlet of the sealing station.

[0034] A preferred embodiment provides that the rubberized deflection roller configured for angle detection, or the rubberized rotary encoder roller, serves as the drive roller to move the top film in the take-off direction, with the absence of a separate rotary encoder deflection roller for this drive roller. The angle of rotation of the drive roller could be detected by a sensor of a servo motor used to control the drive roller. In particular, the drive roller could be positioned at the input or output of the sealing tool. It would also be conceivable to use several such drive rollers along the top film transport device, for example, one at the input of the sealing tool and another at the output, at least one of which is equipped with an angle detector.One approach involves measuring the rotation angle of a film roll holder used to support a film roll for each film feed. This rotation angle can be used to calculate the actual film pull-off length, for example, by taking into account the film roll diameter, which tends to decrease with each film feed.

[0035] Slip detection could be achieved, in particular, by comparing the rotation angle measured at the film reel mandrel with the rotation angle of the drive roller. In this approach, it would be conceivable that the rotation angle could be measured using an existing sensor on a servo motor used to rotate the film reel mandrel. Alternatively, the film reel mandrel could be configured as a rotary encoder to measure its rotation angle for each film feed. If the measured rotation angle of the film reel mandrel decreases too much or does not increase quickly enough, this indicates that the top film is slipping on the drive roller, meaning the film feed is subject to slippage.

[0036] One conceivable control system would compare a curve for each film feed between a target gradient for the rotational speed increase of the film roll holder mandrel and the corresponding actual gradient. If a predetermined deviation occurs, the control system can issue a warning signal indicating a slippage in the film feed and, if necessary, initiate a machine stop.

[0037] According to an advantageous embodiment of the invention, the top film transport device is configured to detect the decreasing diameter of a film roll mounted on the top film transport device during operation as the top film is pulled off. The film roll diameter thus continuously or incrementally detected can serve as a measured value for calculating the actual film pull-off length performed per film feed. In particular, the detected film roll diameter can be combined with the detected rotation angle of the film roll receiving mandrel to determine the actual film pull-off length.

[0038] In particular, the top film transport device is configured to detect the rotation angle of a drive shaft of a servo motor used for film feeding. This can be achieved using a rotary encoder integrated into the servo motor. The servo motor can be located as a drive unit at the film intake or as a drive unit at the film rewinder of the packaging machine.

[0039] In particular, the upper film transport device features a control loop for dynamically controlling the film feed. This control loop can dynamically regulate the film feed intermittently or continuously.

[0040] It would be conceivable that at least one adjustable clamping unit, for example an existing deflection and / or drive roller, could be used along the upper film transport device as an actuator of the control loop device, which can be dynamically adjusted in response to a deviation between the actual film pull-off length and the target film pull-off length that may be detected by the control loop device.

[0041] One variant provides that the top film transport device has at least one measuring device, based on whose measured values ​​a temperature-dependent coefficient of expansion of the top film can be calculated. The calculated coefficient of expansion can be taken into account as a temperature-related disturbance variable when recording the actual film pull-off length and / or when controlling the top film transport device to compensate for an actual film pull-off length that does not meet the target or tolerance values.

[0042] An advantageous variant provides that the upper film transport device can be dynamically controlled to compensate for film slippage, depending on a deviation detected during film feed by comparing the target and actual film take-off lengths. This allows for dynamic control of the film feed during the process itself, enabling corrections to be made within the same work cycle or film feed.

[0043] In particular, a film slippage warning message can be issued when the deviation reaches a preset initial threshold. This warning message can be displayed to an operator via a display device, informing them about film slippage or a gradually increasing amount of it.

[0044] It would be advantageous for the packaging machine to be able to be stopped, meaning that the machine would stop if the detected deviation reaches a preset second threshold that is higher than the first. This machine stoppage would allow for a response to film slippage that exceeds the tolerance limits and would otherwise result in incompletely sealed packages.

[0045] Exemplary embodiments of the invention are explained in more detail with reference to the following figures. They show: Figure 1 shows a tray sealing machine in a schematic, perspective view, Figure 2 shows a tray sealing machine in a side view, Figure 3 shows another tray sealing machine in a side view, and Figure 4 shows a schematic top view to capture a sufficient film feed.

[0046] Technical features are consistently identified in the figures using the same reference symbols.

[0047] Figure 1Figure 1 shows a tray sealing machine 1 with a top film transport device 2 for transporting a top film 3. The top film 3 is unwound from a film feeder 4 and fed by the top film transport device 2 in the take-off direction R to a sealing tool 5 of a sealing station S, in order to seal trays T held in a sealing tool lower part 6 by means of a sealing tool upper part 7 using the top film 3. The trays T can be picked up from a feed conveyor 9 by means of a gripper device 8 and transferred to the sealing tool lower part 6. The sealed and cut packages V can be picked up from the sealing tool lower part 6 by means of the gripper device 8a and transferred to a downstream discharge conveyor 10 for removal. The cutting of the packages V creates a film remnant grid 11 in the top film 3, which is wound onto a film remnant winder 12.

[0048] Furthermore, the tray sealing machine 1 has a control unit 13. This unit's function is to control and monitor the processes taking place on the tray sealing machine 1. In particular, the control unit 13 controls an intermittent film feed in the take-off direction R in order to feed the top film 3 to the sealing station S in cycles according to a target film feed length L. If the measured actual film feed length I does not correspond to the target film feed length L, the film feed is subject to slippage.

[0049] Figure 2 shows a variant of the tray sealing machine 1 from Figure 1The upper film transport device 2, which is formed thereon, has a rubberized deflection roller 14 with a rotary encoder 15. The deflection roller 14 can be configured as a drive roller to pull the upper film 3 from the film holder 4 through the sealing tool 5 in the take-off direction R for each film feed and to feed the film grid 11 formed in the upper film 3 to the film rewinder 12. It would be conceivable for the deflection / drive roller 14 to be supported by another drive roller, for example, a rubberized drive roller positioned at the entrance of the sealing station S.

[0050] Furthermore, it shows Figure 2An ultrasonic sensor 16 is configured to detect a film roll diameter D. The actual film length I of the top film 3 dispensed per film feed can be determined from the film roll diameter D and based on a detected rotation angle of a film roll mandrel 17 of the film holder 4, or optionally based on the number of revolutions of the film roll mandrel 17. The film roll diameter D is detected continuously by the ultrasonic sensor 16. The number of revolutions of the film roll mandrel 17 and / or its rotation angle can be detected by an encoder on the film roll mandrel 17.Since the rotation angle of the film roll holder mandrel 17 increases continuously with decreasing film roll diameter D per film feed, slippage of the film transport can already be deduced on the basis of the detected rotation angle of the film roll holder mandrel 17, for example if the rotation angle does not increase as desired according to a predetermined gradient.

[0051] A corresponding warning message can be displayed on the integrated display unit 18 by comparing the target and actual take-off lengths via the control unit 13 when the comparison reaches a first threshold value. In particular, the control unit 13 can trigger a machine stop if the comparison reaches an even higher, second threshold value.

[0052] Figure 3Figure 1 shows another tray sealing machine 1' with a top film transport device 2 for detecting a film feed of the top film 3. This top film transport device 2 has a rubberized drive roller 19 with a counter-pressure roller 20 for the film feed of the top film 3. The drive roller 19 is located on the inlet side at the sealing station S. The material of the top film 3 unwound from the film intake 4 is guided to the drive roller 19 by a rubberized deflection roller 21. The rubberized deflection roller 21 is equipped with a rotary encoder 22. The rotary encoder 22 detects a rotation angle for each film feed. Using the known diameter of the rubberized deflection roller 21, the actual film feed length I can be calculated. This is then compared with the target film feed length L by the control unit 13. If the difference reaches the first threshold value, a corresponding message can be issued.Upon reaching the second threshold, a machine stop can even be initiated.

[0053] Figure 4Figure 1 shows a schematic representation of the sealing tool 5 from a top view. A measuring device 24 is arranged on the exit side of the sealing tool 5 in the pull-off direction R. This device is configured to detect an area 23 behind the last cutout A of the film grid 11. This measurement takes place within a track width, i.e., a width perpendicular to the pull-off direction R, of the last cutout A of the film grid 11. If the area 23 can be detected by the measuring device 24, for example, a distance sensor, this indicates that the top film 3 has been pulled sufficiently far out of the sealing tool 5 by the film feed, so that the trays T held within the lower part of the sealing tool 6 can be completely sealed with the top film 3.However, if the measuring device 24 does not detect area 23, but instead detects the last cutout A in the pull-off direction R, this may indicate that the top film 3 has been moved with slippage. In other words, this means that the last cutout A located in the film grid 11 is still within the sealing tool 5, possibly even overlapping with the packaging T in the first position, i.e., there is an open area.

Claims

1. Method for monitoring a film feed of a top film (3) used for sealing packaging bases (T) fed by the sealing tool (5) on a sealing tool (5) of a packaging machine, carried out intermittently by means of a top film transport device (2), characterized by the fact that It is checked whether, during film feed, the top film (3) is moved in the pull-off direction (R) according to a preset target film pull-off length (L).

2. Method according to claim 1, characterized by the fact that For each film feed in the pull-off direction (R) behind the sealing tool (5) at least one measurement is carried out to detect a film grid (11) pulled out of the sealing tool (5) in the track width of a last cutout (A) of the film grid (11) following an area (23) of the top film (3).

3. Method according to claim 1 or 2, characterized by the fact thatFor each film feed, a rotation angle of a rubberized deflection roller (14, 21) of the upper film transport device (2) used for the film feed is measured.

4. Method according to any of the preceding claims, characterized by the fact that For each film feed, a rotation angle of a film roll holding mandrel (17) used to store a film roll is measured.

5. Method according to any of the preceding claims, characterized by the fact that per film feed, a film roll diameter (D) of a film roll mounted on the upper film transport device (2) is detected and / or a rotation angle of a drive shaft of a servo motor used for the film feed is measured.

6. Method according to any of the preceding claims, characterized by the fact that A control loop device dynamically controls the film feed.

7. Method according to any of the preceding claims, characterized by the fact thatthe upper film transport device (2) reacts dynamically to film slippage detected by a target / actual film take-off length comparison during a film feed and / or issues a film slippage warning message when the deviation reaches a preset first threshold.

8. Method according to claim 7, characterized by the fact that The packaging machine will be stopped if the detected deviation reaches a preset second threshold that is higher than the first threshold.

9. Packaging machine, in particular designed in the form of a tray sealing machine (1), comprising a sealing station (S) with a sealing tool (5) for receiving packaging bases (T) and a top film transport device (2) for transporting a top film (3) through the sealing tool (5) in order to seal packaging bases (T) received therein by means of the top film (3), characterized by the fact that the top film transport device (2) is configured to check whether the top film (3) is moved further in the pull-off direction (R) according to a preset target film pull-off length (L) during a film feed.

10. Packaging machine according to claim 9, characterized by the fact that In the direction of extraction (R) on the exit side of the sealing tool (5) at least one measuring device (24) for detecting a film grid (11) pulled out of the sealing tool (5) in a track width of a section of the film grid (11) following an area (23) of the top film (3).

11. Packaging machine according to claim 9 or 10, characterized by the fact that the upper film transport device (2) has at least one rubberized deflection roller (14, 21) with a rotary encoder (15, 22).

12. Packaging machine according to one of claims 9 to 11, characterized by the fact thatthe upper film transport device (2) is configured to detect a rotation angle of a film roll receiving mandrel (17) used for storing a film roll.

13. Packaging machine according to one of claims 9 to 12, characterized by the fact that the top film transport device (2) is configured to detect a film roll diameter (D) of a film roll mounted on the top film transport device (2) which decreases during operation by removing the top film (3) and / or to detect a rotation angle of a drive shaft of a servo motor used for film feed.

14. Packaging machine according to one of claims 9 to 13, characterized by the fact that the upper film transport device (2) has a control loop device for dynamically controlling a film feed.

15. Packaging machine according to one of claims 9 to 14, characterized by the fact thatthe upper film transport device (2) can be dynamically controlled for film slip compensation depending on a deviation detected during film feed by means of a target / actual film take-off length comparison and / or a film slip warning message can be issued when the deviation reaches a preset first threshold value, in particular operation of the packaging machine can be stopped when the detected deviation reaches a preset second threshold value that is higher than the first threshold value.

Images