Thermoforming packaging machine and method for controlling a foil punch

Description

[0001] The invention relates to a thermoforming packaging machine according to the preamble of claim 1. Furthermore, the invention relates to a method according to the preamble of claim 13.

[0002] A thermoforming packaging machine of this type is known from EP 3 109 017 B1. A film punch, assumed to be known in this device, for cutting through a film is adjusted between an open and a closed position by means of a pneumatic cylinder. In the associated force curve, there is a sudden drop in force, whereby the cutting of the film is indicated in the force diagram. Nevertheless, the pneumatic cylinder continues to build up a contact force until a pressure bar of the film punch presses against a knife of the film punch with a preset maximum force, before the cutting process ends and the pressure of the pneumatic cylinder is released. However, the film punch, which repeatedly operates up to the preset maximum force level per cutting cycle, results in significant wear on the knife.

[0003] As an alternative to the embodiment described above, EP 3 109 017 B1 proposes, according to another variant, a cutting process controlled by a servo motor, in which the blade of the film punch is intended to be subjected to less stress per cutting cycle than in the pneumatic embodiment. For this purpose, the servo motor always moves the pressure bar to a preset working position which corresponds to a specific position of the servo motor. The working position can be calibrated weekly, daily or each time the thermoforming packaging machine is started by moving the pressure bar until it contacts the blade when no film is present and storing a detectable angle on the output shaft of the servo motor in the control system as the working position. However, this increases the calibration effort, since the film punch should be readjusted, especially when changing the film.

[0004] US 2003 / 126963 A1 discloses a cutting device in which a force curve is recorded during the cutting process. Based on the force curve recorded during the cutting of a film and the subsequent maximum force of the processing cycle, the degree of wear of the blade used in the cutting device is determined using a calculated difference. Based on this difference, a control signal can be generated to adjust the operation of the cutting device.

[0005] The object of the invention is to provide a thermoforming packaging machine and a method for controlling a film punch whose operation is even more efficient than the solutions used in the prior art, so that, above all, shorter production cycles and a lower degree of wear of the components used in the film punch can be achieved.

[0006] This object is achieved by a thermoforming packaging machine having the features of claim 1. Furthermore, this object is achieved by means of a method having the features of claim 13. Advantageous developments of the invention are specified in the dependent claims.

[0007] The invention relates to a thermoforming packaging machine with a forming station for thermoforming troughs into a film web, a filling section for filling products into the troughs, a sealing station for sealing the troughs, a chain guide for guiding a transport chain for the film web, a cross-cutting device for severing the film web in a direction transverse to the transport direction, a longitudinal cutting device for severing the film web in the transport direction and a control device for controlling processes taking place on the thermoforming packaging machine.

[0008] The cross-cutting device comprises a foil punch, an adjustment drive for closing and opening the foil punch, which can be controlled by means of the control device, and a detection unit which is connected to the control device and which has at least one sensor which is designed to record a force curve occurring on the foil punch during opening and closing per processing cycle.

[0009] A characteristic of the intermittently operating thermoforming packaging machine is that the control device is designed to carry out a dynamic adjustment of the control signal for opening and / or closing the film punch per processing cycle of the film punch in the event of a temporary drop in force detected by the sensor during a tendency of force increase in the force curve, by means of which a severing of the film web by means of a knife of the film punch can be determined.

[0010] In contrast to a preset working position, to which the foil punch moves per processing cycle, as well as a preset maximum cutting force, with which the foil punch operates per processing cycle, according to the prior art, the invention uses the signal detected per processing cycle based on the force drop in the force curve, i.e., dynamically to adapt the control signal of the control device for opening and / or closing the foil punch. Thus, during operation of the thermoforming packaging machine, the force curve can be automatically optimized for each processing cycle of the foil punch, making the operation of the foil punch even more precise and less prone to wear.

[0011] Because the control signal on the control device is automatically adjusted for each processing cycle, i.e., each cutting process, with respect to the event of the detected breakthrough of the film, the optimal operation of the film punch can be self-regulated on the thermoforming packaging machine. In the invention, in contrast to the previously known approach with a predetermined working position or maximum cutting force, the film punch operates dynamically for each processing cycle with respect to cutting through the film. This means that, depending on the time at which the cutting through of the film is detected, the subsequent force curve for opening and / or closing the film punch can be adapted for each processing cycle.

[0012] A dynamic adjustment of the control signal could, for example, arise from the fact that, upon detecting the breakthrough of the film, the controller is configured to slow down a stroke speed for closing the film punch, to terminate the closing of the film punch abruptly or with a time delay before the film punch is fully closed, and / or to control an increase in force following the detection of the breakthrough of the film until the opening of the film punch with a lower temporal force change rate compared to a force change rate of the force increase detected before the film punch is broken. According to the invention, upon detecting the breakthrough of the film, the controller is configured to generate a start signal depending on the drop in force, in particular in real time, whereby the opening of the film punch can be triggered with or without a time delay.

[0013] One variant provides for the sensor to have a measuring socket and at least one strain gauge attached to the measuring socket. This would allow the force curve, particularly the force drop that occurs when the film is cut, to be recorded using simple, cost-effective design means.

[0014] The measuring bushing is preferably positioned by sliding it onto a vertical drawbar of the foil punch. This allows the measuring bushing to be attached to the foil punch in a cost-effective manner and can be easily integrated into the foil punch's power flow. Such a measuring bushing could also be easily retrofitted to existing foil punches, i.e., to existing thermoforming packaging machines. For its measuring application, the measuring bushing could be positioned on the drawbar using a simple handle.

[0015] A variant advantageous for measuring purposes provides for the measuring bushing to be preloaded on the drawbar by means of a (screw) nut when the foil punch is in the open position. By pressing the foil against the blade, i.e., when the foil punch is closed, this preload can be relieved at least until the foil is severed, which can be detected by the strain gauge as a tendency for force to increase in the force curve. Due to the preload of the measuring bushing, the strain gauge attached to it can, in particular, quickly detect changes in the force curve of the foil punch.

[0016] The drawbar preferably has a threaded section for securing the nut. This threaded section can be a fine-pitch thread. This allows the nut's preload to be adjusted particularly precisely. Furthermore, the increased self-locking of a fine-pitch thread allows for better measurement results for numerous machining cycles.

[0017] According to one embodiment, the compression of the measuring bushing, adjusted along the drawbar by means of a nut, is greater than the longitudinal extension of the drawbar occurring during operation of the foil punch. This allows the force distribution when the foil is pressed against the knife to be measured using the resulting longitudinal extension of the measuring bushing.

[0018] The sensor technology used on the foil punch could be improved if the strain gauge were designed as a semiconductor strain gauge and / or a rosette strain gauge. This would allow the force curve to be recorded even more precisely and, above all, the force drop (i.e., the cutting of the foil) even more precisely in real time. This would allow the control signal of the controller to be dynamically adjusted in a responsive manner to optimize the opening and / or closing of the foil punch per processing cycle.

[0019] Preferably, the strain gauge is arranged on the inner circumference of the measuring sleeve. In this variant, the measuring sleeve acts as a housing for the strain gauge and protects it from unwanted influences, such as moisture. For improved hygienic operation of the foil punch, the measuring sleeve can be made of stainless steel.

[0020] When the foil cutter is closed, the foil web is preferably shifted from its transport plane toward the knife. This allows the foil web to be additionally tensioned, which can accelerate the cutting process and result in a better cut edge on the packaging material.

[0021] The foil punch is particularly robust when the knife is mounted in a fixed position. The adjustment drive can be a servo motor configured to adjust a pressure bar on the foil punch. When the foil punch closes, the pressure bar can press the foil web from below against the knife positioned above it. Cutting through the foil web causes the pressure bar and the knife to come into contact, which usually results in an abrupt drop in the measured force curve.

[0022] It is expedient for the control device to have a controller configured to dynamically adjust a control current for the servomotor of the cross-cutting device for opening and / or closing the foil punch as a control signal. This makes it possible, per processing cycle, to move an output shaft of the servomotor to a dependent angle depending on the detected cutting of the foil web, which angle is dynamically determined in response to the cutting of the foil web. Preferably, retraction of the servomotor, i.e., opening of the foil punch, occurs simultaneously with reaching the adjusted angle or with an adjustable delay time.

[0023] It is conceivable that the dynamic adjustment of the control signal for opening and / or closing the foil punch depends on reaching a predetermined amount of force drop and / or on detecting a delay time following the force drop. This would allow for filtering out disturbances in the force curve.

[0024] A preferred variant provides that the control device is configured to determine the thickness of the film web to be severed based on the detected force curve. This can be achieved by detecting a position of the pressure bar when the film web is not present when the film is closed and comparing it with a position at which the pressure bar is located when the force increase begins with the film present. It is conceivable that a working parameter of the cross-cutting device and / or the longitudinal cutting device can be automatically adjusted based on the detected thickness.

[0025] It is conceivable that the nominal force measured for cutting the film web could be used to dynamically adjust a control signal for controlling the operation of the downstream slitting device. This enables coordinated cooperation between the cross-cutting and slitting devices and thus precise separation of packages along the thermoforming packaging machine.

[0026] It is possible for the control device to be configured to determine the degree of wear of the blade based on a starting point recorded in the force curve, the force recorded for the cutting action, and / or the magnitude of the temporary drop in force. The degree of wear can preferably be visually displayed on the thermoforming packaging machine using a display device provided thereon. It is conceivable for a display device to be formed directly on the foil punch. In this context, it is conceivable that service or repair intervals for the foil punch's blade can be automatically indicated.

[0027] One embodiment provides that the thermoforming packaging machine has a display device on which the force curve of the film punch can be visualized and / or the control device is configured to generate a control algorithm based on the detected force curve and / or on several detected force curves. The display device can be present as part of the display device, preferably as part of an operating panel that is available in the area of ​​the sealing station.

[0028] It is conceivable that the control device is designed to revise the control algorithm on the basis of recorded data from the processing cycles of the film punch and / or other work stations of the thermoforming packaging machine carried out since the machine start-up when the thermoforming packaging machine is switched off or when operation of the thermoforming packaging machine is terminated, so that an update of this is available on the control device of the thermoforming packaging machine when it is restarted.

[0029] The invention also relates to a method for a thermoforming packaging machine for detecting the severing of a film web by means of a film punch of a cross-cutting device provided on the thermoforming packaging machine. For this purpose, a force curve caused by the opening and closing of the film punch is detected at least in sections on the cross-cutting device by means of at least one sensor per processing cycle of the film punch.

[0030] A characteristic of the method according to the invention is that a control device of the thermoforming packaging machine carries out a dynamic adjustment of a control signal for opening and / or closing the film punch per processing cycle of the film punch in response to a temporary drop in force detected by the sensor during a force increase tendency in the force curve, whereby the cutting of the film web by means of a knife of the film punch is detected.

[0031] The foil punch's operation can thus be optimally adapted to each processing cycle because the thermoforming packaging machine, especially the foil punch, reacts dynamically and self-controllingly to the cutting of the foil web. This significantly reduces calibration effort and at least slows down wear on the foil punch's blade.

[0032] A dynamic adaptation of the control signal could, for example, be carried out by the control slowing down a stroke speed for closing the film punch by detecting the breakthrough of the film, ending the closing of the film punch abruptly or with a time delay before the film punch is completely closed, controlling an increase in force following the detection of the breakthrough of the film until the opening of the film punch with a lower rate of change in force over time compared to a rate of change in force of the increase in force detected before the breakthrough of the film, and / or generating a start signal depending on the drop in force, in particular in real time, whereby the opening of the film punch is triggered with or without a time delay.

[0033] According to one embodiment of the invention, the sensor measures the force curve per processing cycle of the foil punch using at least one strain gauge arranged in the force flow on a preloaded measuring bushing. The measuring bushing is mounted on a vertical pull rod of the foil punch using a nut under preload, i.e., under compressive load, so that the compressed measuring bushing expands when the foil web is cut, corresponding to the stretching of the pull rod. The strain gauge attached to the measuring bushing allows the force curve per processing cycle of the foil punching to be precisely determined.

[0034] Preferably, the temporary drop in force is approximately triangular in shape, allowing the sudden punching of the film web to be reliably detected. The triangular shape or a similarly abrupt curve can trigger the adjustment of the control signal, so that the film punch opens simultaneously or with a certain delay.

[0035] In the following, embodiments of the invention are explained in more detail with reference to the figures. In the following: Fig. 1 shows a thermoforming packaging machine in perspective view; Fig. 2a shows a cross-cutting device in the form of a film punch of the thermoforming packaging machine in the open position; Fig. 2b shows the cross-cutting device of Fig. 2a in closed position; Fig. 3 the foil punch with a measuring socket and its enlarged section; Fig. 4 the measuring socket with strain gauges in an isolated view; Fig. 5a a diagram illustrating a position shift of an adjustable pressure bar of the foil punch during a cutting process; and Fig. 5b a force curve detectable on the foil punch during a processing cycle.

[0036] Identical components are provided with the same reference numerals throughout the figures.

[0037] Fig. 1 shows a perspective view of an intermittently operating thermoforming packaging machine 1 according to the invention. The thermoforming packaging machine 1 has a forming station 2, a sealing station 3, a cross-cutting device 4, and a longitudinal cutting device 5, which are arranged in this order in a transport direction R on a machine frame 6. On the input side, a feed roller 7 is located on the machine frame 6, from which a bottom film 8 is pulled. Furthermore, the thermoforming packaging machine 1 has a transport chain 11, which grips the bottom film 8 and transports it further in the transport direction R for each main work cycle.

[0038] In the illustrated embodiment, the forming station 2 is designed as a deep-drawing station in which troughs are formed in the bottom film 8 by deep drawing, for example by means of compressed air or vacuum. The forming station 2 can be designed such that several troughs are formed next to one another in the direction perpendicular to the transport direction R.

[0039] In the transport direction R behind the forming station 2, a filling section 12 is provided in which the troughs formed in the bottom film 8 are filled with products.

[0040] The sealing station 3 has a hermetically sealable chamber 3a in which the atmosphere in the troughs can be evacuated, for example, and / or replaced by gas purging with a replacement gas or a gas mixture before sealing with the upper film 10 released from an upper film holder 9.

[0041] The cross-cutting device 4 comprises a foil punch 15 (see Fig. 2a ), which cuts the lower film 8 and the upper film 10 (hereinafter also referred to as film web 8, 10) in a direction transverse to the transport direction R between adjacent troughs. The cross-cutting device 4 operates in such a way that the lower film 8 is not cut across its entire width, but rather remains uncut at least in one edge area. This enables controlled further transport through the transport chain 11.

[0042] The longitudinal cutting device 5 can be designed as a knife arrangement with which the lower film 8 and the upper film 10 are severed between adjacent troughs and at the lateral edge of the lower film 8 in the transport direction R, so that individual packages are present behind the longitudinal cutting device 5.

[0043] The right and left transport chains 11 of the thermoforming packaging machine 1, which grip the bottom film 8 on both sides, are each guided in a chain guide 13. The chain guides 13 are each protected externally by a side panel 14 of the thermoforming packaging machine 1 and, if necessary, are attached to the side panel 14. The side panel 14 can be a sheet metal part.

[0044] The thermoforming packaging machine 1 further comprises a control device 19. Its task is to control and monitor the processes taking place in the thermoforming packaging machine 1. A display device 20 with operating elements 21 serves to visualize or influence the process sequences in the thermoforming packaging machine 1 for or by an operator.

[0045] Fig. 2a shows the foil punch 15 of the cross-cutting device 4. The foil punch 15 is located in Fig. 2a in an open position. Fig. 2a shows in a schematic representation that the control device 19 is functionally connected to an adjustment drive 16 of the foil punch 15. The adjustment drive 16 is configured to open and close the foil punch 15 and can have a servo motor. Furthermore, the foil punch 15 has a detection unit 17, which is functionally connected to the control device 19 and which has a sensor 18, which is designed to detect a force curve K occurring on the foil punch 15 during opening and closing per processing cycle (see Fig. 5b ) to record.

[0046] The foil punch 15 has a knife 22 which, according to Fig. 2a Furthermore, the foil punch 15 has an adjustable pressure bar 30, which Fig. 2a is arranged in a lowered position. The adjustable pressure bar 30 is adjusted in height by means of the adjustment drive 16, whereby it presses against the fixed knife 22 from below during a processing cycle for severing the film web 8, 10.

[0047] In Fig. 2b The knife 22 and the pressure bar 30 are arranged in contact with each other. The foil punch 15 is located in Fig. 2b therefore in a closed position. With the film web 8, 10 clamped between them, the force curve K can be detected by the sensor 18 of the detection unit 17 and transmitted to the control device 19. Based on the force curve K, the adjustment drive 16 of the film punch 15 can be dynamically controlled by adapting a control signal x.

[0048] Fig. 3 shows the foil punch 15 in an enlarged view, in particular an enlarged section of the detection unit 17. The detection unit 17, in particular the sensor 18, is in the form of a measuring socket 23. The measuring socket 23 is pushed onto a vertical pull rod 24. According to Fig. 3 The measuring bushing 23 is preloaded on the pull rod 24 by means of a nut 25. The pull rod 24 has a threaded portion 31 for fastening the nut and for adjusting the preload on the measuring bushing 23.

[0049] During the punching process, when the pressure bar 30 presses against the knife 22 from below, the drawbar 24 extends, so that a support 26 formed thereon for the measuring bushing 23 moves downwards in the direction y, whereby the measuring bushing 23 sitting thereon expands in the direction y. The expansion of the measuring bushing 23 due to the tensile stress of the drawbar can be recorded by means of a strain gauge 27 attached to the measuring bushing. This is shown in the enlarged section C of the Fig. 3 The measuring socket 23 has been shown in the enlarged section C of the Fig. 3 on its inner side 28 (see also Fig. 4 ) opposite strain gauges 27. The strain gauges 27 measure the force curve K during the processing cycle of the foil punch 15, ie in particular during the punching process, in which the pressure bar 23 presses the foil web 8, 10 from below against the knife 22 positioned above it.

[0050] Fig. 4 shows the sensor 18 in an isolated view. The measuring socket 23 is designed as a short piece of tubing and has opposing strain gauges 27 on its inner side 28. At the measuring socket 23, the strain gauges 27 are connected using a full bridge (bridge circuit) to record the force curve K during a processing cycle of the foil punch 15.

[0051] On the foil punch 15, the measuring bushing 23, which is pushed onto the drawbar 24 and preloaded thereon, forms a cost-effective means for recording the force curve K. Calibration of the measuring bushing 23 can be easily performed by adjusting the preload force using the nut 25. The arrangement of the measuring bushing 23 on the drawbar 24 largely compensates for influences caused by temperature changes and / or bending of the drawbar 24. The strain gauges 27 can also be well protected against external influences by the surrounding measuring bushing 23 and can be easily replaced.

[0052] Fig. 5a shows a position shift P of the pressure bar 30 and Fig. 5b shows the corresponding force curve K during a processing cycle D of the foil punch 15.

[0053] When the foil punch 15 is open at the start time t1 of a processing cycle D, the pressure bar 30 is in the position shown in Fig. 2a shown position.

[0054] At time t2, the pressure bar 30 and the knife 22 clamp the film web 8, 10 between them. As the pressure bar 30 presses the film web 8, 10 from below against the knife 22 positioned above it, the film web 8, 10 is severed, which in Fig. 5b The force curve K shown is illustrated by the sudden drop in force E at the cutting time t3. Here, a tendency towards an increase in force Z suddenly decreases in the force curve K. This means that the film web 8, 10 is completely severed and the pressure bar 30 is in contact with the knife 22.

[0055] Fig. 5b shows schematically that the force curve K determined by means of the detection unit 17, in particular the determined force drop E, is detected by the control device 19, which is designed to dynamically adapt the control signal x for opening the foil punch 15 in response thereto. A controller 35 of the control device 19 can be used, in particular, for the control signal adaptation. The control signal x, which is repeatedly redetermined for each processing cycle D, regulates the activation of the adjustment drive 16, in particular a servo motor 36, of the foil punch 15 in order to activate the pressure bar 30 depending on the detected severance of the foil web 8, 10.

[0056] According to Fig. 5b the sudden drop in force E has a triangular curve V. The triangular curve V and / or an amount B as a deflection for the drop in force E can be present as a prerequisite for a dynamic adaptation of the control signal x.

[0057] In response to the severing of the film web 8, 10, the control device 19 can adjust the control signal x for the adjustment drive 16 such that the knife 22 and the pressure bar 30 are further pressed together upon contact until a time t4. The duration of the time interval t3 - t4 can be variably adjusted on the control device 19.

[0058] From time t4, the foil punch 15 opens, i.e., the pressure bar 30 returns to the open position, causing the measured force to decrease from time t4 until time t5. From time t5, the pressure bar 30 and the knife 22 are no longer in contact.

[0059] It is conceivable that the time t4 can be determined when a certain amount of force increase is reached during the time interval t3 - t4, ie the control signal x is dynamically adapted accordingly.

[0060] The Fig. 5a und 5bshow that the beginning of the breakage of the film web 8, 10 is detected by the sudden, temporary drop in force E in the force curve K. This makes it possible to close the film punch 15 in each processing cycle D until a breakage of the film web 8, 10 is detected. Furthermore, unnecessary overloading of the knife 22 can be avoided by closing the film punch 15 only until the breakage of the film web 8, 10 is detected, or with a slight time delay.

[0061] Based on the force curve K described above, it is possible to determine whether there is actually a film web 8, 10 in the film punch 15 by evaluating characteristic points (such as the pressure bar 30 striking the film web 8, 10 at time t2 and the knife 22 leaving the pressure bar 30 at time t5). If a film web 8, 10 is present, the positions M (pressure bar 30 striking the film web 8, 10) and N (leaving the lower edge of the knife) differ, with these detection values ​​M, N being identical if there is no film. If a missing film web 8, 10 is detected, an emergency stop function not according to the invention could be triggered on the thermoforming packaging machine 1.

Claims

1. Thermoforming packaging machine (1) with a forming station (2) for thermoforming troughs in a film web (8, 10), a filling path (12) for filling products into the troughs, a sealing station (3) for sealing the troughs, a chain guide (13) for guiding a transport chain (11) for the film web (8, 10), a transverse cutting device (4) for cutting the film web (8, 10) in a direction transverse to the transport direction (R), a longitudinal cutting device (5) for cutting the film web (8, 10) in the transport direction (R), and a control device (19) for controlling processes running on the thermoforming packaging machine (1), wherein the transverse cutting device (4) comprises a film punch (15), an adjustment drive (16) which can be controlled by means of the control device (19) for closing and opening the film punch (15), and a detection unit (17) which is connected to the control device (19) and which has at least one sensor (18) which is configured to detect, per processing cycle (D), a force progression (K) occurring at the film punch (15) during opening and closing, characterized in that the control device (19) is configured to carry out, per processing cycle (D) of the film punch (15), a dynamic adaptation of a control signal (x) in the subsequent force progression for opening and / or closing the film punch (15) as a function of a temporary slump in force (E) detected by means of the sensor (18) during a tendential increase in force (Z) in the force progression (K), as a result of which a cutting of the film web (8, 10) by means of a knife (22) of the film punch (15) can be detected, wherein by detecting the break-through of the film web (8, 10) the control device (19) is configured to generate a start signal as a function of the slump in force, in particular in real time, whereby the opening of the film punch (15) can be triggered with or without a time delay.

2. Thermoforming packaging machine according to claim 1, characterized in that the sensor (18) comprises a measuring socket (23) and at least one strain gauge (27) attached to the measuring socket (23).

3. Thermoforming packaging machine according to claim 2, characterized in that the measuring socket (23) is pushed onto a vertical tie rod (24) of the film punch (15).

4. Thermoforming packaging machine according to claim 2 or 3, characterized in that the measuring socket (23) is arranged pretensioned on the tie rod (24) by means of a nut (25).

5. Thermoforming packaging machine according to claim 4, characterized in that a compression of the measuring socket (23) set along the tie rod (24) by means of the nut (25) is greater than a longitudinal extension of the tie rod (24) occurring during operation of the film punch (15).

6. Thermoforming packaging machine according to one of the preceding claims 2 to 5, characterized in that the strain gauge (27) is configured as a semiconductor strain gauge and / or as a rosette strain gauge.

7. Thermoforming packaging machine according to one of the preceding claims 2 to 6, characterized in that the strain gauge (27) is arranged on an inner circumference (28) of the measuring socket (23).

8. Thermoforming packaging machine according to one of the preceding claims, characterized in that when the film punch (15) is closed, the film web (8, 10) is displaced out of its transport plane in the direction of the knife (22).

9. Thermoforming packaging machine according to one of the preceding claims, characterized in that the control device (19) comprises a controller (35) which is configured to adapt, as a control signal (x), a control current for a servomotor (36) of the transverse cutting device (4) for opening and / or closing the film punch (15).

10. Thermoforming packaging machine according to one of the preceding claims, characterized in that the control device (19) is configured to determine a thickness of the film web (8, 10) to be cut on the basis of the detected force progression (K).

11. Thermoforming packaging machine according to one of the preceding claims, characterized in that the control device (19) is configured to determine a degree of wear of the knife (22) on the basis of a start time (t3) detected in the force progression (K) and / or an amount (B) of the temporary slump in force (E).

12. Thermoforming packaging machine according to one of the preceding claims, characterized in that the thermoforming packaging machine (1) has a display device (20), on which the force progression (K) of the film punch (15) can be visualized and / or the control device (19) is configured to generate a control algorithm on the basis of the detected force progression (K).

13. Method on a thermoforming packaging machine (1) for detecting a cutting of a film web (8, 10) by means of a film punch (15) of a transverse cutting device (4) provided on the thermoforming packaging machine (1), wherein a force progression (K) caused by opening and closing of the film punch (15) is detected at least in sections on the transverse cutting device (4) by means of at least one sensor (18) per processing cycle (D) of the film punch (15), characterized in that a control device (19) of the thermoforming packaging machine (1) carries out a dynamic adaptation of a control signal (x) in the subsequent force progression for opening and / or closing the film punch (15) per processing cycle (D) of the film punch (15) in response to a temporary slump in force (E) detected by means of the sensor (18) during a tendential increase in force (Z) in the force progression (K), as a result of which the cutting of the film web (8, 10) is indicated by means of a knife (22) of the film punch (15), wherein by detecting the break-through of the film web (8, 10) the control device (19) is configured to generate a start signal as a function of the slump in force, in particular in real time, whereby the opening of the film punch (15) can be triggered with or without a time delay.

14. Method according to claim 13, characterized in that the sensor (18) measures the force progression (K) by means of at least one strain gauge (27) attached to a pretensioned measuring socket (23).

15. Method according to claim 13 or 14, characterized in that the temporary slump in force (E) has approximately the shape of a triangular progression (V).