EP3476753A1 - Deep draw packaging machine and method for operating the same - Google Patents

Abstract

In a method of operating a thermoforming packaging machine (1) having as work stations a forming station (2) for deepening cavities (14) in a packaging film (8), at least one sealing station (3a, 3b) for sealing the cavities (14) with a Covering film (10) and a cutting station (4, 5) and a feed device (11) for effecting a feed of the packaging film (8) determines a controller (18) before a work step for two or more workstations (2, 3a, 3b, 4), which Vorschublängebedarf (V3a, V3b, V4) each of these workstations (2, 3a, 3b, 4) respectively, wherein the feed length requirement (V3a, V3b, 4) indicates by which route the packaging film (8) for the next Step of the respective workstation (2, 3a, 3b, 4) must be transported before from the determined Vorschublängenbedarfen (V3a, V3b, V4) a Vorschublängevorgabe (W) won and the feed device (11) is driven accordingly.

Description

The invention relates to a method for operating a thermoforming packaging machine and to such a thermoforming packaging machine itself.

A generic thermoforming packaging machine, for example, from the DE 10 2015 211 622 A1 out. Such packaging machines are characterized by a forming station for deep-drawing of troughs in a packaging film and usually comprise a sealing station for sealing the deep-drawn troughs with a lid film and a cutting station for separating the produced packaging. Furthermore, these machines include a feed device for effecting feed of the packaging film.

In most cases, such thermoforming packaging machine is operated intermittently or intermittently. In each work cycle, the packaging film is transported by the feed device by a constant, fixed feed length forward. In this case, the feed length is also referred to as the "take-off length". It indicates the length of each format produced in a single cycle of packaging in the direction of production of the thermoforming packaging machine.

In order to be able to keep the feed length from stroke to stroke exactly constant, enormous efforts are sometimes made. For example, describes the DE 42 16 209 C2 a thermoforming packaging machine in which the packaging film is provided with so-called printing marks at regular intervals. After these print marks have been detected by means of a corresponding print mark sensor, in the packaging machine of DE 42 16 209 C2 various work stations are changed in their position in the longitudinal direction of the packaging machine, so that they are set to the ideal position relative to the print marks. This makes it possible to keep the feed length of the packaging film constant in each working cycle. In the machine the EP 2 860 119 however, the length of a film feed is controlled with respect to an exact target position only in the sealing station.

The object of the present invention is to improve a thermoforming packaging machine and a method of operating such thermoforming packaging machine in terms of versatility and efficiency.

This object is achieved by a method having the features of claim 1 or by a thermoforming packaging machine with the features of claim 7. Advantageous developments of the invention are specified in the dependent claims.

• Die Steuerung ermittelt vor einem Arbeitsschritt für zwei oder mehr Arbeitsstationen, welchen Vorschublängenbedarf jede dieser Arbeitsstationen jeweils hat, wobei der Vorschublängenbedarf angibt, um welche Strecke die Verpackungsfolie für den nächsten Arbeitsschritt der jeweiligen Arbeitsstationen transportiert werden muss,
• aus den ermittelten, mehreren Vorschublängenbedarfen wird eine Vorschublängenvorgabe gewonnen und
• die Vorschubeinrichtung wird dazu angesteuert, die Verpackungsfolie um eine der Vorschublängenvorgabe entsprechende Vorschublänge zu transportieren.

The inventive method relates to the operation of a thermoforming packaging machine, the control (eg a programmable logic controller [PLC] or a microprocessor) and workstations as a forming station for deep drawing of wells in a packaging film - usually a plastic packaging film -, at least one sealing station for Sealing the troughs with a lidding film and a cutting station, wherein the thermoforming packaging machine further comprises a feed device for effecting a feed of the packaging film. The method for operating this thermoforming packaging machine has the following steps:

• For one or more workstations, the controller determines which feed length requirement each of these workstations has in each case, the feed length requirement indicating by which route the packaging film must be transported for the next work step of the respective workstations,
• From the determined, multiple feed length requirements, a feed length specification is obtained and
• the feed device is driven to transport the packaging film by a feed length corresponding to the feed length specification.

The invention thus solves the hitherto preferred concept of keeping the feed length as constant as possible before each work step. By one step is meant performing a primary function of the respective workstation, ie deep-drawing of wells into the packaging film at a forming station, sealing of the wells with a lid film at a sealing station or producing a cut in the packaging film at a cutting station. The invention now considers that the feed length requirement may be different for different workstations. First, therefore, the Vorschublängenbedarfe of two or more workstations, possibly even of all workstations, gathered together before a single Vorschublängevorgabe is obtained from the plurality, possibly different Vorschublängenbedarfen. The feed device is then driven, preferably by means of the control of the thermoforming packaging machine, to transport the packaging film by a feed length corresponding to the feed length specification.

By these measures, it is a great advantage of the invention that not only the respective workstations can act on the optimal locations on the packaging film, but that the thermoforming packaging machine beyond even be able to without changing the packaging material and even in irregular Follow different packaging formats to produce and process.

Preferably, the feed length requirement of the two or more workstations is determined before each individual feed of the packaging film, and from this a feed length specification is obtained. Analogously, it is conceivable that the thermoforming packaging machine is cyclically, in particular in regular work cycles, operated and that the Vorschublängenbedarfe the two or more workstations determined in each individual power stroke and from a Vorschublängevorgabe is obtained. In this way, the invention unfolds its advantages over the entire operation of the thermoforming packaging machine.

In a variant, the feed device can be controlled to transport the packaging film by a feed length that corresponds to the smallest determined feed length requirement. On the one hand, this has the advantage that, with this measure, the time duration for the next advance is kept particularly low, and thus the overall performance of the thermoforming packaging machine is increased. On the other hand, this measure makes it possible, after the work step has been carried out by the workstation which has the smallest feed length requirement, to adjust the feed of the packaging film to the feed length requirement of those workstations which have a greater feed length requirement. Thus, finally, each of the participating workstations perform their work step. This variant of the invention is particularly suitable when the positions of the individual workstations along the thermoforming packaging machine are invariable.

It is also conceivable, however, a variant of the method in which the position of at least one of the workstations in a production direction of the thermoforming packaging machine is adjustable and is adjusted when performing the method. In addition to the degree of freedom in the selection of the feed length specification, the second degree of freedom is changed by changing the position of the at least one workstation in the production direction of the thermoforming packaging machine. Several or even all workstations could be changeable in their position in the direction of production. With this second degree of freedom, the flexibility of the use of thermoforming packaging machine is further increased. In addition, this variant of the method opens the possibility to further increase the performance of the thermoforming packaging machine by the Vorschublängevorgabe and the positioning of the workstations with the aim of a possible high cycle performance of the packaging machine can be coordinated and optimized by as many of the workstations can perform their work step in each cycle.

If the positions of not only a single but several of the work stations of the thermoforming packaging machine are adjustable in the direction of production over a predetermined travel range, it may be particularly favorable to determine a feed length specification range for each of these workstations, taking into account the respective travel range. The minimum of this feed length default range is the feed length that would be required for the particular workstation as the workstation moves to its furthest upstream position prior to the next operation. The maximum of the feed length specification area is the feed length that would be required if the respective work station is moved to its furthest downstream position prior to its next operation. The difference between the maximum and the minimum of the feed length specification range thus corresponds to the length of the travel range of the respective workstation.

In this variant of the method, it is advantageous if the feed length specification is selected from an overlap region in which the feed length specification ranges of the workstations adjustable in their position in the direction of production overlap. For example, the feed length specification could be selected from the middle third of the overlap area or even exactly at the midpoint of the overlap area.

The invention also relates to a thermoforming packaging machine, which has as workstations at least one forming station for deep-drawing of trays in a packaging film, at least one sealing station for sealing these trays with a lid film and at least one cutting station, wherein the thermoforming packaging machine further comprises a feed device for effecting a feed of the Packaging film and a controller (eg a programmable logic controller [PLC] computer or a microprocessor) includes. The invention is characterized in that the feed device is configured to produce a variable feed length per work step of the thermoforming packaging machine, that the controller has a detection section that is configured to determine a feed length requirement of the respective workstation for two or more workstations an evaluation section configured to determine a feed length preset from the feed length requirements of the two or more workstations and that the controller is configured to drive the feed device to move the wrapping film by a feed length corresponding to the feed length preset.

The determination section of the controller can either itself calculate which feed length requirements the two or more workstations have, or it can receive the respective feed length requirements from the workstations. The invention deviates, as already carried out for the inventive method, from the concept of a fixed feed length. The variable feed length enables optimized operation of the thermoforming packaging machine and, in particular, alternating or even irregular processing of formats of different sizes.

The feed device can be configured to produce a stepwise or even a continuously variable feed length. While a stepwise changeable feed length minimizes the required computational effort for the control, a continuously variable feed length enables even more versatile operation of the thermoforming packaging machine.

It is expedient if the feed device comprises a staple chain with a controllable servo motor. While the staple chain securely grips the packaging film, the servomotor can be controlled with different feed length specifications.

The evaluation section of the controller is preferably configured to determine the lowest feed length requirement. In this case, the controller is arranged to control the feed device for moving the packaging film by a feed length corresponding to the smallest feed length requirement. As already stated above, this variant is particularly advantageous if the positions of the individual workstations along the thermoforming packaging machine are invariable.

In another variant of the invention, however, the position of at least one of the workstations, preferably several or even all workstations, is adjustable in the direction of production. This makes it possible to change the position of the work stations in such a way that, in conjunction with the variable feed length specification, the work of the thermoforming packaging machine is maximized.

If even the positions of several of the workstations in the production direction over a respective predetermined range of travel are adjustable, it is particularly advantageous if a Vorschublänge range can be determined for each of these workstations, taking into account their travel range. As already stated with respect to the method, it is further particularly advantageous if the evaluation section is configured to determine an overlapping area in which the feed length specification areas of the position in Production direction adjustable workstations overlap, and to select the Vorschublänge from the overlap area.

Fig. 1

eine schematische Ansicht einer Tiefziehverpackungsmaschine,

Fig. 2A

eine schematische Darstellung von zwei unterschiedlichen, auf der Tiefziehverpackungsmaschine hergestellten Formaten,

Fig. 2B bis 4C

verschiedene Zustände im Betrieb der Tiefziehverpackungsmaschine nach Figur 1,

Fig. 5A

ein zweites Ausführungsbeispiel zweier unterschiedlicher, mittels der Tiefziehverpackungsmaschine herstellbarer Formate,

Fig. 5B bis 5E

verschiedene Zustände im Betrieb der Tiefziehverpackungsmaschine,

Fig. 6A

ein drittes Ausführungsbeispiel zweier unterschiedlicher, mit der Tiefziehverpackungsmaschine herstellbarer Formate,

Fig. 6B bis 6D

verschiedene Zustände im Betrieb der Tiefziehverpackungsmaschine,

Fig. 6E

eine schematische Darstellung des Überlappungsbereichs und

Fig. 7

eine schematische Darstellung aus dem Betriebsablauf der Tiefziehverpackungsmaschine.

In the following, embodiments of the invention are illustrated in more detail with reference to a drawing. In detail show:

Fig. 1

a schematic view of a thermoforming packaging machine,

Fig. 2A

a schematic representation of two different formats produced on the thermoforming packaging machine,

Figs. 2B to 4C

various states during operation of the thermoforming packaging machine according to FIG. 1,

Fig. 5A

A second embodiment of two different, producible by the thermoforming packaging machine formats,

Fig. 5B to 5E

various states during operation of the thermoforming packaging machine,

Fig. 6A

A third embodiment of two different, producible with the thermoforming packaging formats,

Fig. 6B to 6D

various states during operation of the thermoforming packaging machine,

Fig. 6E

a schematic representation of the overlap area and

Fig. 7

a schematic representation of the operation of the thermoforming packaging machine.

The same components have been provided throughout the figures with the same reference numerals.

FIG. 1 shows a schematic side view of a thermoforming packaging machine 1. This thermoforming packaging machine 1 has a forming station 2, a first sealing station 3a, a second sealing station 3b, a cross-cutting device 4 and a longitudinal cutting device 5, which are arranged in this order in a production direction P on a machine frame 6 , On the input side is located on the machine frame 6, a feed roller 7, from which a packaging film 8 is withdrawn. In the area of the sealing stations 3 a, 3 b, a material reservoir 9 is provided, from which a cover film 10 is pulled off. On the output side, a discharge device 13 in the form of a conveyor belt is provided on the packaging machine, with the finished, isolated packaging be transported. Furthermore, the packaging machine 1 has a feed device 11 which grips the film 8 and transports it intermittently per main working cycle in the production direction P. The feed device 11 may, for example, have staple chains 12 acting on both sides of the packaging film 8.

The forming station 2 is designed as a deep-drawing station, in which molds 14 are formed into the packaging film 8, usually a plastic film, by deep-drawing. In this case, the forming station 2 can be designed such that in the production direction P and / or in the direction perpendicular to the production direction P a plurality of wells are formed side by side. In the production direction P behind the forming station 2, an insertion path 15 is provided in which the troughs 14 formed in the packaging film 8 are filled with a product 16.

Each sealing station 3a, 3b has a closable chamber 17 in which the atmosphere in the wells 14 can be replaced prior to sealing, for example, by gas purging with a replacement gas or with a gas mixture.

The cross-cutting device or cutting station 4 is designed as a punch which cuts through the packaging film 8 and the cover film 10 in a direction transverse to the production direction P between adjacent depressions 14. In this case, the cross-cutting device 4 operates such that the packaging film 8 is not separated over the entire width, but at least in an edge region is not severed. This allows a controlled onward transport by the feed device 11.

In the illustrated embodiment, the longitudinal cutting device or second cutting station 5 is designed as a knife arrangement with which the packaging film 8 and the cover film 10 are severed between adjacent depressions 14 and at the lateral edge of the packaging film 8, so that there are individualized packages behind the longitudinal cutting device 5.

The packaging machine 1 also has a controller 18. It has the task of controlling and monitoring the processes taking place in the packaging machine 1. A display device 19 with operating elements 20 serves for visualizing or influencing the process sequences in the packaging machine 1 for or by an operator.

The general operation of the thermoforming packaging machine 1 will be briefly described below.

The packaging film 8 is withdrawn from the feed roller 7 and transported by the feed device 11 in the forming station 2. In the forming station 2 are formed by deep drawing troughs 14 in the packaging film 8 is formed. The troughs 14 are transported along with the surrounding area of the packaging film 8 to the insertion path 15. During the feed movement or at a stationary feed a product 16 is inserted into the wells 14.

Subsequently, the filled wells 14 are transported by the feed device 11 to the sealing station 3a, 3b. In the sealing station 3a, 3b, the troughs 14 can optionally be evacuated and / or fumigated with an inert gas before the lidding film 10 is sealed onto the troughs 14 to close the troughs 14 hermetically. The transverse and longitudinal cutting devices 4, 5 provide for a separation of the troughs 14, which are finally transported on the discharge device 13. A controllable by the controller 18 servomotor 12 a is provided as a drive for the staple chain 12.

FIG. 1 already indicates two different embodiments of the thermoforming packaging machine 1. In the first embodiment, the position of the work stations 2, 3a, 3b, 4, 5 in the direction of production P of the thermoforming packaging machine 1 is fixed. In a second embodiment, however, the position of certain workstations, in this case specifically the two sealing stations 3a, 3b, can be changed independently of one another in the production direction P. This means that the respective workstations 3a, 3b can be moved in or against the production direction P. For this purpose, each of the two sealing stations 3a, 3b is assigned in each case a linear drive 21, which can be activated by the controller 18 and is configured to change the position of the respective sealing station 3a, 3b over a respective travel range 22a, 22b.

FIG. 2A schematically shows in plan view a first format F1 and a second format F2, which are producible with the thermoforming packaging machine 1. It would be conceivable, for example, for the thermoforming packaging machine to have two forming stations 2 in the production direction P one behind the other, one of which generates an arrangement of packaging trays 14 in F1 format, while the other is capable of producing an array of trays 14 in F2 format. One format is in each case a group of depressions 14, which are produced together in one step in the packaging film 8. Alternatively, a single mold station 2 can produce the two different formats.

The two in FIG. 2A F1, F2 shown by way of example are multi-row and multi-track, ie they each comprise a plurality of tracks S of troughs 14 side by side both parallel to the production direction P, ie also several rows R of troughs 14 one behind the other, transversely to the production direction P. The first format F1 comprises three tracks S and three rows R, of which each individual row R in the production direction P has a so-called "row length" RL of 100 mm. Overall, this results in the production direction P an overall length (so-called "take-off length", AZL) of the format F1 of 300 mm.

The second format F2, however, also comprises three tracks S, but with only two rows R. Each row R here has a "row length" RL in the production direction P of 150 mm. Thus, the second format F2 has the same take-off length AZL of 300 mm in the production direction P as the first format F1.

FIG. 2B shows a schematic plan view of the thermoforming packaging machine 1 at a specific time in the operation. It can be seen that there is always a first format F1 and a second format F2 alternately in the production direction P. The first sealing station 3a is configured to seal the troughs 14 of a first format F1 with the lidding film 10. This means that a sealing tool of the first sealing station 3a, for example, a so-called sealing glasses, has a contour corresponding to the division of the troughs 14 in the first format F1 and is thus able to provide each trough 14 of the first format F1 with a circumferential sealing seam. By contrast, the second sealing station 3b is set up to seal the wells of the second format F2. This means that a sealing tool of the second sealing station 3b, for example a sealing eyeglasses of the second sealing station 3b, has a contour corresponding to the division of the depressions in the second format F2. As a result, the second sealing station 3b is able to provide each trough 14 in the second format F2 with a circumferential sealed seam. The cross-cutting device 14 generates a cut transversely to the direction of production P through the packaging film 8 at the in FIG. 2B shown location. In this embodiment, the positions of the work stations 3a, 3b, 4 are not variable in the direction of production P.

One operation of the first sealing station 3a is to seal the troughs 14 of a format F1, which is done by applying suitable pressure and heat to the packaging film 8 and the lidding film 10. An operation of the second sealing station 3b is analogous to producing a seal of the troughs 14 of the second format F2, while a step of the cutting station or cross-cutting device 4 in severing the packaging film 8 by means of a suitable cutting tool, for example a knife exists.

The FIGS. 2C to 2E show which feed length requirement the workstations 3a, 3b, 4 respectively in the situation in the operating state of the thermoforming packaging machine 1, the in FIG. 2B was shown. The term "feed length requirement" means the distance by which the packaging film 8 has to be transported, so that the respective work station 3a, 3b, 4 can carry out its next work step.

Figure 2C X1 denotes the first format F1 that is closest to the upstream of the first sealing station 3a and thus to be sealed next to the first format F1 in the sealing station 3a. For the sealing to take place, the format X1 must be transported completely into the first sealing station 3a. The feed length requirement V3a, by which the format X1 must be transported for this purpose, is here 300 mm, ie corresponds exactly to a take-off length AZL of the first format F1.

FIG. 2D shows that at this time immediately upstream of the second sealing station 3b is a first format F1, which can not be sealed in the second sealing station 3b (and in any case already must be sealed by the first sealing station 3a). X2 denotes the second format F2, which is located upstream upstream of the second sealing station 3b. In order for this format X2 to be sealed in the second sealing station 3b, it is necessary to advance the packaging film 8 by a distance of 600 mm. This means that the feed length requirement V3b of the second sealing station 3b in this situation corresponds to 600 mm and thus to a double take-off length.

In the same operating state shows Figure 2E This is only half a take-off length, ie 150 mm, until the next cross-section behind the next row R can take place X3.

The controller 18 of the thermoforming packaging machine 1 comprises, as in FIG. 1 illustrated, a determination section 18a, which is adapted to determine for two or more workstations 3a, 3b, 4, a feed length requirement V3a, V3b, V4 of the respective workstations 3a, 3b, 4. For this purpose, the determination section 18a can be set up, for example, to receive and store the feed length requirement V3a, V3b, V4 of the respective workstations 3a, 3b, 4. Alternatively, the determination section 18b may be configured, for example, in the form of a path controller and be capable of having, at all times, knowledge of the positions of the respective formats F1, F2 and the parting lines between two adjacent rows R in the production direction P of the thermoforming packaging machine. This enables the determination section 18a to calculate even the feed length requirement V3a, V3b, V4 of the respective work stations 3a, 3b, 4. The determination section 18a may also be configured to recognize whether it already has knowledge of the current feed length requirement of each of the workstations 3a, 3b, 4 to be considered.

The controller 18 further includes an evaluation section 18b configured to determine a feed length preset VV from the determined feed length requirements V3a, V3b, V4. This feed length default VV finally transmits the controller 18 as a control command the feed device 11, in the illustrated embodiment concretely to the servo motor 12a, so that this the staple chain 12 and thus the covered by this packaging film 8 by a Vorschublängevorgabe VV corresponding feed length V transported in the production direction P.

In the in the Figures 2B to 2E Thus, the determination section 18a determines the respective feed length requirements V3a, V3b, V4 of the workstations 3a, 3b, 4. The evaluation section 18b is configured in this exemplary embodiment to determine the smallest of the determined feed length requirements V3a, V3b, V4 as the feed length specification VV. In the situation described, V3a = 300 mm, V3b = 600 mm, V4 = 150 mm. The smallest of these values is V4 = 150 mm, so the feed length default is VV = 150 mm.

The Vorschublängevorgabe VV is passed as a command to the feed device 11, which then causes a transport of the packaging film 8 by a corresponding feed length V = 150 mm, as in Figure 2F shown. In the in Figure 2F shown situation, the cutting station 4 can now perform their next step, ie cut through the packaging film 8 at the point X3. The two sealing stations 3a, 3b, however, remain inactive, so they can not yet perform their respective work step.

FIG. 3A shows starting from the in Figure 2F situation reached the feed length requirement V3a the first sealing station 3a. The format X1 must be transported further by a length of V3a = 150 mm, so that the format X1 is completely in the first sealing station 3a and can be sealed. This remaining feed length requirement V3a already results as a difference between the feed length requirement V3a according to FIG Figure 2C and the intermediate feed V of the packaging film 8 according to FIG Figure 2F ,

FIG. 3B analogously shows the current feed length requirement V3b of the second sealing station 3b. Here, the format X2 must be transported on by a length of V3b = 450 mm in order to be sealed in the second sealing station 3b.

Finally shows FIG. 3C the new feed length requirement V4 of the cross cutting station 4. So that behind the next, located upstream of the cutting station 4 row R of packaging trays 14, a cross section of a point X4 can be set for the cutting station 4, a feed length requirement V4 of 150 mm.

After determining the respective feed length requirements V3a, V3b, V4 by the determination section 18a, the evaluation section 18b determines the smallest feed length requirement, here V3a = V4 = 150 mm, and sets this as the feed length specification VV = 150 mm.

Figure 3D shows the situation after the packaging film 8 starting from FIG. 3C by the Vorschublängevorgabe VV corresponding feed V = 150 mm was further transported. In the situation according to FIG. 3d, both the next working step of the first sealing station 3a can take place, ie the sealing of the format X1 as well as the next working step of the cutting station 4, ie the severing of the packaging film 8 at the point X4.

FIG. 4A shows starting from Figure 3D the feed length requirement V3a of the first sealing station 3a. The next, first format F1 located upstream of the first sealing station 3a is located at the point X1 and has to be transported by a feed length V3a = 600 mm in order to be able to be sealed in the first sealing station 3a. The second format F2 located next to the second sealing station 3b is located at the point X2 and has to be transported by a distance of V3b = 300 mm in order to be sealed in the second sealing station 3b.

FIG. 4B shows in this situation the feed length requirement V4 of the cross-cutting station 4. Immediately upstream of the cutting station 4 is now a first format F1 with a row length RL = 100 mm (see FIG. 2A ). So that the cutting station 4 can set the next cut at the point X5, ie behind the next row R, the cutting station 4 has a feed length requirement V4 = 100 mm.

Among the determined feed length requirements V3a = 600 mm, V3b = 300 mm, V4 = 100 mm, the smallest value of the feed length requirement V4 = 100 mm is the cutting station 4. The evaluation section 18b determines this smallest feed length requirement V4 and transmits it to the feed device 11 as the feed length specification VV ,

FIG. 4C shows the situation after the thus driven feed device 11, the packaging film 8 has transported by a feed length V = 100 mm forward. The cutting station 4 can now set the cut at the point X5.

FIG. 5A shows a second embodiment of two formats F1, F2. Here is the first format F1 two-lane and single-row, with a take-off length AZL = 260 mm. The second format F2, however, is three-lane and two-row, also with a take-off length AZL = 260 mm.

FIG. 5B shows a certain operating state of the thermoforming packaging machine 1. Alternately one behind the other on the packaging film 8 first and second formats F1, F2 of wells 14 have been generated. The first sealing station 3a is configured to seal the first format F1, while the second sealing station 3b is configured to seal the wells 14 of a second format F2.

FIG. 5C shows the feed length requirement V3a of the first sealing station 3a. The next first format F1 upstream of the first sealing station 3a is at location X1. The feed length requirement V3a of the first sealing station 3a is thus 195 mm.

FIG. 5D shows at the same time the feed length requirement V3b of the second sealing station 3b. Upstream of the second sealing station 3b is the nearest second format F2 at the point X2. The feed length requirement V3b of the second sealing station 3b is thus V3b = 520 mm. If only the two sealing stations 3a, 3b are to be considered, the evaluation section 18b determines the value V3a = 195 mm as the smallest feed length requirement and transmits this as the feed length specification to the feed device 11.

FIG. 5E shows the situation after the feed device 11 has transported the packaging film 8 in accordance with the Vorschublängevorgabe VV by the feed rate V = 195 mm forward. The first sealing station 3a can now carry out its next work step and seal the format X1 with the cover film 10.

FIG. 6A shows a third embodiment of two different formats F1, F2, which can be generated with a forming station 2 or two successively arranged forming stations 2 in the packaging film 8. The first format F1 comprises three troughs 14 of different sizes and in the production direction P has a total "take-off length" AZL = 240 mm. The second format F2, however, consists in a 3x3 arrangement each about the same size packaging trays 14 (ie three tracks S and three rows R) and has a total take-off length AZL = 200 mm.

FIG. 6B shows in plan view a certain operating state of the thermoforming packaging machine 1, which comprises a first sealing station 3a for sealing first formats F1 and downstream of which a second sealing station 3b for sealing second formats F2 of wells 14. In this exemplary embodiment, the positions of each of the two sealing stations 3a, 3b in the production direction P are variable. Specifically, the position of the first sealing station 3a can be moved by means of an associated linear drive 21 over a travel range 22a, which in FIG. 6B is shown and has a total length of eg 675 mm. The position of the second sealing station 3b can analogously by means of an associated linear drive 21 via a travel range 22b with a total length of, for example, 585 mm in the production direction (ie parallel to the production direction P) are adjusted.

FIG. 6C visualizes the feed length requirement V3a of the first sealing station 3a. In order to bring the first format F1, which is located at the point X1 and thus closest upstream of the first sealing station 3a, to the instantaneous position of the first sealing station 3a, a minimum feed rate V3a _min = 440 mm would be required. However, the first sealing station 3a can also be brought to the furthest downstream end of its travel range 22a, as indicated by the reference numeral 3a '. To bring the next format X1 into this position, a feed of V3a _max = 875 mm would be required. The feed length requirement V3a of the first sealing station 3a is therefore not a singular value here, but rather a feed length specification range VBa (see FIG FIG. 6E ), which ranges from the minimum value V3a _min to the maximum feed length requirement V3amax.

Analog visualized FIG. 6D the at the same time existing feed length requirement V3b of the second sealing station 3b. In order for it to be able to seal the second format F2 situated at the point X2 upstream upstream of the second sealing station 3b, this (and thus the packaging film 8 as a whole) must be transported forward at least by V3b _min = 585 mm. Taking into account the travel range 22b of the second sealing station 3b, the film advance can be at most V3b _max = 970 mm when the second sealing station 3b is brought into its furthest downstream position. The feed length setting range VBb of the second sealing station 3b thus ranges from 585 mm to 954 mm, as in FIG FIG. 6E shown.

After the determination section 18a of the controller 18 has determined the feed length specification ranges VBa, VBb as feed length requirements, the evaluation section 18b determines therefrom an overlapping area UB in which the feed length specification ranges VBa, VBb, of the involved workstations 3a, 3b overlap. From this overlapping area UB, the evaluation section 18b selects a specific value as the feed length specification VV. For example, this may be a value in the middle third of the overlapping area UB, preferably even the mean value of the overlapping area UB. Alternatively, it would be conceivable that the evaluation section 18b selects the lowest value of the overlapping area UB in order to keep the feed length V as small as possible. The selected feed length setting W is given as a control command to the feed device 11, so that they transported the packaging film 8 by a corresponding feed length V forward.

A further variant of the control method could be optimized to select the feed length preset VV from the overlapping area UB such that the workstations involved remain as close as possible to a central area of their respective travel areas 22a, 22b.

In yet another variant, the evaluation section 18b may be configured to select the feed length preset VV from the overlapping area UB in view of minimizing the total time to the next work step, since this will increase the overall performance of the thermoforming packaging machine 1. For this purpose, it would be possible for one or more of the involved workstations to be moved upstream, i. contrary to the direction of the film feed, in order to obtain as quickly as possible a new situation, which allows a work step of any workstation.

FIG. 7 shows in a flow chart some steps from the method according to the invention or from the operation of the thermoforming packaging machine. 1

At S1 the machine is switched on. At S2, a referencing of the current position of the servo motor 12a of the feed device 11 takes place.

At S3, a query is made as to whether the next film feed should be released. This involves a query as to whether each work station 2, 3a, 3b, 4, 5 has completed a work step intended for it.

In parallel with this, the determination section 18a of the controller 18 determines the feed length requirements V3a, V3b, V4 ... of all workstations 3a, 3b, 4 to be considered in step S4. It transfers the determined values to the evaluation section 18b of the controller 18, which derives therefrom in step S5 generates a feed length preset VV.

As soon as the release for the next advance of the packaging film 8 has taken place in step S3, a control command corresponding to the feed length specification V.sub.V takes place to the drive 12a of the feed device 11 in step S6.

In step S7, the servomotor 12a starts feeding the feeding device 11 and maintains it in step S8 until a query in step S9 shows that the positioning target has been reached, ie, the feed has been made by the desired feed length V. The method then proceeds back to step S3, in which after the execution of the respective work steps of the workstations 3a, 3b or 4, the release for the next feed takes place.

The core of the invention is therefore that the feed length is no longer held constant from power stroke to power stroke, but on the contrary can vary from each step to the next step, especially taking into account the individual Vorschublängenbedarfe several workstations.

Starting from the illustrated embodiments, the method and the thermoforming packaging machine 1 can be modified in many ways. Of course, the values given are merely examples that have been used for purposes of illustration only. It is quite conceivable to process more than two different formats F1, F2 on a thermoforming packaging machine 1 according to the invention, for which purpose a corresponding number of sealing stations 3a, 3b are provided. Of course, the configuration of the formats F1, F2 can also deviate significantly from the illustrated examples. It would also be conceivable to consider an upper film printing station for printing on the upper film with its feed length requirement as a workstation in the method according to the invention.

Claims (13)

Method for operating a thermoforming packaging machine (1) comprising a controller (18) and, as work stations, a forming station (2) for deepening depressions (14) in a packaging film (8), at least one sealing station (3a, 3b) for sealing the wells ( 14) with a cover film (10) and a cutting station (4, 5), wherein the thermoforming packaging machine (1) further comprises a feed device (11) for effecting a feed of the packaging film (8),
the method comprising the steps of: - The controller (18) determines before a step for two or more workstations (2, 3a, 3b, 4), which Vorschublängenbedarf (V3a, V3b, V4) each of these workstations (2, 3a, 3b, 4), respectively the feed length requirement (V3a, V3b, V4) indicates by which route the packaging film (8) has to be transported for the next work step of the respective workstations (2, 3a, 3b, 4), a feed length specification (VV) is obtained from the determined feed length requirements (V3a, V3b, V4), - The feed device (11) is driven to transport the packaging film (8) by one of the Vorschublängevorgabe (VV) corresponding feed length (V). A method according to claim 1, characterized in that in each working cycle of the cyclically operated thermoforming packaging machine (1) or before each feed of the feed length requirement (V3a, V3b, V4) of the two or more workstations (2, 3a, 3b, 4) determined and a Vorschublängevorgabe (VV) is won. A method according to claim 1, characterized in that the feed device (11) is driven to transport the packaging film (8) by a feed length (V), which corresponds to the smallest determined feed length requirement (V3a, V3b, V4). Method according to one of the preceding claims, characterized in that the thermoforming packaging machine (1) has a production direction (P) and the position of at least one of the workstations (2, 3a, 3b, 4) in the production direction (P) is adjusted. Method according to one of the preceding claims, characterized in that the positions of a plurality of the workstations (2, 3a, 3b, 4) in the production direction (P) via a predetermined travel range (22a, 22b) are adjustable, and that for each of these workstations (2, 3a, 3b, 4), taking into account the travel range (22a, 22b), a feed length specification range (VBa, VBb) is determined. Method according to Claim 5, characterized in that the feed length setting (W) is selected from an overlapping area (UB) in which the feed length specification ranges (VBa, VBb) of the work stations (3a, 3b, 4) adjustable in their position in the production direction (P) overlap. Thermoforming packaging machine (1) used as workstations
at least one forming station (2) for deep-drawing of cavities (14) in a packaging film (8), at least one sealing station (3a, 3b) for sealing the cavities (14) with a lid film (10) and at least one cutting station (4, 5) the thermoforming packaging machine (1) further comprising feed means (11) for effecting feed of the wrapping film (8) and a controller (18),
characterized,
in that the feed device (11) is configured to produce a feed length (V) which is variable per working step of the thermoforming packaging machine (1),
in that the controller (18) has a determination section (18a) which is set up for two or more workstations (2, 3a, 3b, 4) a feed length requirement (V3a, V3b, V4) of the respective workstation (2, 3a, 3b , 4) to determine
in that the controller (18) has an evaluation section (18b) configured to determine a feed-forward preset (VV) from the feed-length requirements (V3a, V3b, V4) of the two or more workstations (2, 3a, 3b, 4),
and that the controller (18) is adapted to drive the feed device (11) for moving the packaging film (8) by a feed length (V) corresponding to the feed length setting (W). Thermoforming packaging machine according to claim 7, characterized in that the feed device (11) is configured to produce a step-wise or continuously variable feed length (V). Thermoforming packaging machine according to one of claims 7 or 8, characterized in that the feed device (11) comprises a staple chain (12) with a controllable servo motor (12a). Thermoforming packaging machine according to one of claims 7 to 9, characterized in that the Auswertektion (18b) is configured to determine the lowest feed length requirement (V3a, V3b, V4), and that the controller (18) is adapted to drive the feed device (11) for moving the packaging film (8) by a feed length (V) corresponding to the smallest feed length requirement (V3a, V3b, V4). Thermoforming packaging machine according to one of claims 7 to 9, characterized in that the thermoforming packaging machine (1) has a production direction (P) and the position of at least one of the workstations (2, 3a, 3b, 4) in the production direction (P) is adjustable. Thermoforming packaging machine according to claim 11, characterized in that the positions of several of the workstations (2, 3a, 3b, 4) in the production direction (P) over a predetermined travel range (22a, 22b) are adjustable, and that for each of these workstations (2, 3a , 3b, 4), taking into account your travel range (22a, 22b), a feed length specification range (VBa, VBb) can be determined. Thermoforming packaging machine according to claim 12, characterized in that the evaluation section (18b) is configured to determine an overlapping area (UB) in which the feed length specification ranges (VBa, VBb) of their position adjustable in the production direction (P) in workstations (2, 3a, 3b , 4) overlap, and to select the feed length default (W) from the overlap area (UB).

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