EP3587286B1 - Method for determining process parameters for a packaging machine - Google Patents

Description

The invention relates to a method for producing packs with pack optics at least substantially similar to one another according to claim 1. Furthermore, the invention relates to a packaging machine for producing packs with pack optics at least substantially similar to one another according to independent claim 13.

The invention is in particular the following in connection with Fig. 1 problem described.

Fig. 1 shows a schematic representation of a sealing station S '. The sealing station S 'comprises an upper sealing tool part SO' and a lower sealing tool part SU ', which can be brought together by means of a lifting movement H' to form an airtight sealed sealing chamber SK '. For a gassing and / or evacuation process, an upper film O 'and a lower film U' are brought together within the sealing chamber SK 'in such a way that they enclose a packing volume P' between them, which is essentially the sum of a partial volume V1 'that is determined by the respective Packaging trays VM 'formed in the lower film U' minus the present product contents I ', as well as a partial volume V2' which is present above the respective packaging trays VM 'and is enclosed by the upper film O'.

The package volume P ′ is designed to be overall larger than the totality of the respective individual volumes enclosed by the packages produced, so that gas can be distributed between the packages during the gassing in particular. Because of the in Fig. 1 Positioning of a sealing tool SW 'stored therein above the packaging troughs VM' positioned within the sealing station S ', a gap SP' between the lower and upper film U ', O', via which the supplied gas is in all, shown, in the sealing tool upper part SO 'set back can distribute packaging positioned within the sealing station S '.

When the pack volume P 'is re-compressed, i.e. when the top film O' is pressed down for the sealing process, packaging with varying pack optics can be produced despite an optimized gassing process, for example using an adjustable stage throttle, because it happens again and again that doing that Packagings are produced that have different upper film curvatures, for example appear puffed or rather depressed.

These optical deviations are caused in the sealing process by the lifting (lowering) of the sealing tool SW '. Since the sealing tool SW 'is initially positioned set back in the sealing tool upper part SO' during the gassing process in order to create the gap SP 'required for the distribution of the gas, the sealing tool SW' is then moved downwards for the sealing process in the direction of the packaging tray VM positioned below 'relocated, whereby it displaces the initially created partial volume V2'. By moving the sealing tool SW 'down, the gassed partial volume V2' is pressed into the partial volume V1 ', so to speak as an additional volume. As a result, the pressure in the packaging increases. Depending on the varying packaging contents I ', packaging with a varying packaging appearance is thereby created.

The following applies here: the smaller the freely available partial volume V1 ', the greater the influence of the partial volume V2' displaced by the sealing stroke on the change in pressure within finished packaging.

Up to now, attempts have been made to counteract the problems described above with a preset offset offset printing, i.e. at the beginning only a pressure reduced by the offset offset pressure was used in the hope that the desired target pressure within the packaging would then be achieved through the sealing stroke .

The use of fumigation offset printing, however, requires knowledge of the degree of filling of the respective packaging to be closed, whereby for the sake of simplicity in conventional applications it was previously assumed that the product line has a constant degree of filling over the respective packaging. As a result, it always becomes problematic if, contrary to the assumption mentioned above, the respective packaging does not have a uniform degree of filling, which can apply in particular to products with a target weight with varying product density, for example sliced meat or cheese. Despite the use of a predetermined gas offset printing, finished packaging with a different visual appearance is produced due to varying fill levels.

In addition, the gassing offset printing previously had to be calculated manually during a setting process and entered as a calculation parameter on the packaging machine, so that its use is reserved for specially trained operating personnel.

Working with constant, preset process parameters therefore does not provide the desired manufacturing quality and can be optimized in particular with regard to manufacturing tailored to each individual product.

The operation of a packaging machine assuming a constant filling level across the respective packaging and / or a constant volume flow predetermined for the gassing, without taking into account the respective actual filling levels of individual packages, can lead to a not insignificant amount of rejects.

This can be influenced by the fact that empty packaging temporarily repeatedly goes through the gassing and / or evacuation process within the product line, for example due to interruptions in product provision. The empty packaging then carried along then extremely falsifies the gassing and / or evacuation process, provided that rigidly preset process parameters are used. As a result, at least the filled packaging processed together with the empty packaging in one work cycle does not produce the desired appearance.

The EP 2 668 102 B1 discloses a packaging machine and a method for producing individually evacuated and / or gassed packages. It is generally further disclosed that a means can be used with which the filling level of the packaging material in the respective packaging tray and / or the filling quantity of the packaging material within the respective packaging tray can be determined. Depending on this measurement signal, a shut-off device can then be regulated, for example, in order to individually regulate the volume of gas that is withdrawn from or supplied to the respective packaging tray.

The object of the invention is to produce a method and a device for producing packs with pack optics that are at least substantially similar to one another. This should be possible even if the respective packagings have varying degrees of filling, i. H. are bulky unevenly filled.

This object is achieved by means of a method according to claim 1 and by means of a packaging machine according to independent claim 13.

Improved further developments of the invention are the subject of the respective subclaims.

• Befüllen eines zwischen einem unteren und einem oberen Verpackungsmaterial eingeschlossenen, freien Packungsvolumens mindestens einer innerhalb der Siegelstation positionierten Verpackung mit einem zur Schaffung einer gewünschten Atmosphäre bestimmten Gas von einem im Packungsvolumen herrschenden Ausgangsdruck auf einen vorbestimmten Begasungsdruck,
• Erfassen eines Druckverlaufs zumindest temporär während des Befüllens des Packungsvolumens mittels mindestens einer damit verbundenen, druckerfassenden Sensorik, wobei der Druckverlauf vorzugsweise anhand einer zeitabhängigen Druckkurve zwischen dem Ausgangsdruck bis hin zu dem vorbestimmten Begasungsdruck erfasst wird,
• Vergleichen des erfassten Druckverlaufs mit einem Referenzdruckverlauf, der vorzugsweise anhand einer seinerseits zeitabhängigen Druckkurve für ein Befüllen eines bekannten freien Referenzpackungsvolumens mindestens einer innerhalb der Siegelstation positionierten, insbesondere leeren Referenzverpackung mit dem Gas zwischen dem Ausgangsdruck bis hin zu dem vorbestimmten Begasungsdruck erfasst wird, und
• Einstellen mindestens eines Prozessparameters an der Verpackungsmaschine unter Berücksichtigung des Vergleichs des erfassten Druckverlaufs mit dem Referenzdruckverlauf.

The invention relates to a method for operating a sealing station of a packaging machine, in particular a deep-drawing packaging machine. The method is configured to produce packagings with a pack optics that are at least essentially similar to one another with possibly varying degrees of filling. The method according to the invention comprises the following steps:

• Filling a free packaging volume enclosed between a lower and an upper packaging material of at least one packaging positioned within the sealing station with a gas intended to create a desired atmosphere from an initial pressure prevailing in the packaging volume to a predetermined aeration pressure,
• Detection of a pressure profile at least temporarily during the filling of the package volume by means of at least one associated pressure-sensing sensor system, the pressure profile preferably being recorded on the basis of a time-dependent pressure curve between the initial pressure up to the predetermined aeration pressure,
• Comparing the recorded pressure profile with a reference pressure profile, which is preferably recorded on the basis of a time-dependent pressure curve for filling a known free reference package volume of at least one, in particular empty reference package positioned within the sealing station with the gas between the initial pressure up to the predetermined aeration pressure, and
• Setting at least one process parameter on the packaging machine, taking into account the comparison of the recorded pressure profile with the reference pressure profile.

For example, it would be conceivable that a degree of filling of the packaging positioned within the sealing station is calculated based on the comparison of the recorded pressure profile with the reference pressure profile and / or a volume flow with regard to the pressure profile or the reference pressure profile and the at least one process parameter on the packaging machine taking into account the calculated degree of filling and / or the volume flow is set. In this variant, by considering the current pressure profile during the gassing process, a degree of filling of a "fume cupboard" provided within the sealing station, ie the the respective packaging processed per machine cycle in one work process at the sealing station, as well as, if necessary, based thereon, in adaptation to the respective withdrawal, the volume flow of the gassing medium can be determined.

Other basic values that can be calculated from the comparison of the recorded pressure profile with the reference pressure profile and / or can be derived using a characteristic map provided on the packaging machine and that are used to set the percentage parameter would also be conceivable. However, it is also conceivable that the process parameter can be set directly on the basis of the comparison between the recorded pressure profile and the reference pressure profile.

The essence of the invention is, at least temporarily, but preferably right at the beginning of the gassing process, to record the pressure curve on a respective trigger and to compare it with a reference pressure curve that is generated and recorded, for example, on a trigger from empty packaging. By means of an analysis, i.e. a comparison of the respective gradients of the pressure increases, it would be further possible, for example, to calculate the degree of filling of the currently available fume cupboard, i.e. the packaging positioned within the sealing station, as well as, if necessary, an optimal volume flow of the gassing medium used for it based on this, the processing of the present print and / or at least one subsequent print can be carried out in a process-controlled manner.

According to the embodiment, it is therefore possible that current filling level and / or volume flow values can be recorded and used per machine cycle as a basis for calculating at least one process parameter for the manufacturing process, be it at the sealing station itself and / or at other work stations of the packaging machine.

In particular, it is possible with the aid of the invention that the comparison of the pressure curve with the reference pressure curve is carried out in good time, ie during a predeterminable time window at the beginning of filling, that for the same draw in real time, optionally a degree of filling and / or a volume flow can be foreseen (calculable ) is, that is, the process parameter can be set during the remaining filling time, that is, before a variable final gas pressure is reached within the package volume. In other words, the time window for the aforementioned comparison can be timed in such a way that the present print itself can still be influenced in a process-controlled manner based on the comparison carried out in this regard. Such an advantageous cascading can lead to a higher process accuracy.

The invention is based on process steps that can be carried out easily in order to better adapt the manufacturing process to possibly varying fill levels, with the result that an improved product quality, that is to say packs with pack optics that are at least substantially similar to one another, can be produced.

The invention is particularly well suited for the qualitative packaging of each target weight product with varying product volume, in particular for packaging fresh meat or cheese with varying product density. Even in the event that empty packaging is included in the product line for procedural reasons during the manufacturing process, its "empty contents" can be optimally compensated for using the method steps according to the invention, so that even with a withdrawal with empty packaging included therein, packaging can be produced with the desired packaging appearance .

For the optional derivation of the degree of filling, in particular for performing the comparison of the recorded pressure profile with the reference pressure profile, it can be useful to assume an isothermal change in state with the same volume flow conditions, preferably with the same pressure ratios and possibly the same throttle valve position. The derivation is preferably based on the Boyle-Mariotte law as the theoretical basis. It is particularly advantageous if, based on at least one process parameter preset at the sealing station (e.g. aeration temperature, volume flow, pressure ratio, throttle position for gassing, etc.), a corresponding reference pressure curve can be called up for carrying out the inventive method, so that the inventive method in the production of different Packaging types can be used.

An advantageous variant of the invention provides that a quotient of a ratio of a time recorded for the pressure profile and a time recorded for the reference pressure profile is subtracted from a whole in order to calculate the degree of filling.

In order to record and / or calculate the elapsed time for the pressure curve increasing between different pressure levels, which results during the filling within the packaging positioned in the sealing station, a recording and / or calculation unit is preferably used, which may be an integral part of a control unit of the packaging machine is.

It can be advantageous that a variable time window can be selected for recording the pressure profile on the packaging machine. For example, a larger time window for recording the pressure profile could also be selected for longer-lasting gassing processes, because this enables a more precise prediction of the current filling level and / or volume flow to be carried out.

The time-based comparison with the reference pressure profile can take place during the gassing using a previously recorded and / or calculated time for the reference pressure profile. For this purpose, a memory of the packaging machine preferably holds at least one time-dependent reference pressure curve that is predetermined for the packaging format and with respect to which the filling level of the current print can be determined. In particular, reference pressure profiles of different packaging formats can be kept ready for the process-controlled comparison, so that the invention can be used for an optically homogeneous production of different packaging formats. The comparison can be particularly meaningful if comparable process parameters, for example the same volume flows, are used to produce the reference pressure profile and the recorded pressure profile.

In this context, it can be the case in particular that the calculation of the degree of filling and / or the volume flow occurs in real time per machine cycle and that the process parameters are automatically adapted based on this. In this context, real-time is intended to mean that the automated adjustment of the process parameter takes place during the same work cycle, in particular that it can also relate to a setting of the currently performed gassing process, during which the filling level is determined.

It is advantageous if the process parameter is an offset pressure that is still used during the current filling process and / or during at least one subsequent filling process, in order to fill the package volume with gas only until a pressure is reached that results from a target gas pressure for finished packages minus the calculated offset print results.

For an improved production quality, the offset printing could be adapted automatically at least at intervals, but preferably per machine cycle, so that varying fill levels can be better taken into account during production. In particular, it would then be possible to continuously adapt the filling pressure to the detected filling levels, so that the subsequent sealing stroke inside the packaging precisely brings about the target gas pressure. As a result, optically equivalent packaging, i.e. packaging with the same target gas pressure, can leave the sealing station.

The Boyle-Mariotte law is expediently used to calculate the offset printing, taking into account a partial volume of the packaging volume displaced by a sealing stroke and a free packaging volume that can be determined in view of the calculated filling level, including the target gassing pressure to be produced in finished packaging. When applying the Boyle-Mariotte law, an isothermal pressure equalization between the packages that are positioned within the sealing station can be assumed.

The process parameter is preferably a gas velocity which is achieved at the respective gas pens designed to fill the packing volume. This can be useful in view of the nature of the products, particularly the nature of food products placed in the packages. For example, it matters whether dimensionally stable, one-piece products with a solid surface finish, such as B. a piece of cheese, or products with unstable, in particular applied surface properties, e.g. B. breaded meat, are fumigated. Packagings with a high recorded degree of filling, in which breaded meat is inserted, could be fumigated with reduced gas velocity to avoid damage to the breading layer. On the other hand, gassing with a higher gas velocity for one-part pack contents formed with a stable surface could in principle be set for an increased production rate, in particular when a low degree of filling is detected.

According to one embodiment, the process parameter is a valve setting value, in particular a throttle valve position, which influences an evacuation and / or gassing process. In this way, the pressure profile within the packing volume could be influenced in a targeted manner. The valve setting value is preferably continuously adapted automatically during the manufacturing process, so that optimal process settings can always be used. This particularly favors precise gassing and offers excellent control for the manufacture of optically equivalent products.

One embodiment variant provides that the process parameter triggers a malfunction display on the packaging machine. In this way, for example, leaks can be detected during the manufacturing process, in particular during the gassing and / or evacuation process within the sealing station, and can be displayed immediately to the operating personnel so that production can be interrupted if necessary, for example to adjust process parameters on the packaging machine.

The (free) packing volume is preferably connected to a collecting volume of known size and the (free) packing volume is calculated based on a detected pressure equalization. For example, an external storage device, an external gas tank or a volume created by the upper part of the tool of the sealing station can be used as the collecting volume of known size. This procedure can be used in particular for the precise calculation of a reference package volume of empty packages of a fume cupboard, which can then be used when calculating the reference pressure profile.

A separately provided gas tank could be designed to be lockable by means of an additional valve, so that the pressure equalization between it and the free packing volume can be precisely regulated. After the packaging has been gassed to a desired pressure, a pressure change in the gas tank can then be recorded, which is used as the basis for calculating the volume transition, from which the remaining volume, i.e. the (free) packaging volume, can be calculated. The Boyle-Mariotte law could again be used as the basis for calculation.

An improved variant provides that the process parameter is set continuously in view of averaged values of the degree of filling and / or the volume flow. As a result, the control effort on the packaging machine can be reduced. This can be of particular advantage in an operating situation in which there is a high probability that slight changes in the degree of filling will occur, for example when packing sliced sausage.

According to a variant, the pack volume filled with gas is formed in such a way that pressure equalization takes place between several packs positioned within the sealing station during the gassing process, in particular during the sealing stroke. The respective packagings enclosed within a sealing chamber can be connected via a gap formed between the upper and the lower packaging material. Here, the process parameter can be an adjustable speed of a lifting movement of the sealing tool, which is adjustably mounted within the sealing station, so that it moves in such a way that the pressure equalization can take place reliably between the several packagings provided.

A supply line volume connected to the packing volume, which results for example from a gassing line, an evacuation line and / or a tool volume, is preferably deducted when calculating the degree of filling. In addition or as an alternative, the sealing plate stroke, ie the partial volume of the pack displaced as a result, could also be deducted from the calculation of the degree of filling in view of the known geometries of the upper part of the sealing tool become. Assuming that these values, which may falsify the degree of filling calculation, remain constant, standard values that are stored in the machine control can be used.

The principle according to the invention could precede the gassing process and take place during an evacuation process. It would thus be possible to functionally transfer the explanations described above in connection with the invention to the evacuation process, so that a process-controlled parameter setting based thereon can already take place during the evacuation process and then during the gassing process.

Preferably, with the aid of the invention, process parameters can also be set outside the sealing station, i.e. at other work stations of the packaging machine, in such a way that the respective work stations of the packaging machine can work together excellently in order to achieve an improved production result. The invention thus contributes to an overall process-controlled packaging machine.

The invention also relates to a packaging machine, which is in particular in the form of a deep-drawing packaging machine, the sealing station of which is designed to produce packs with a pack optics that is at least substantially similar to one another with possibly varying degrees of filling. In addition to the sealing station, the packaging machine according to the invention comprises a control unit which is functionally connected to at least one sensor system embodied at the sealing station for detecting a pressure of a package volume provided within the sealing station.

According to the invention, the control unit is configured to perform a comparison of a time-dependent, at least temporarily, preferably during filling of the package volume enclosed within the sealing station between predetermined pressure levels, with a time-dependent reference pressure profile stored between the predetermined pressure levels in the control unit for filling a known reference volume, wherein the control unit is further designed to set at least one process parameter on the packaging machine, taking into account the comparison of the recorded pressure profile with the reference pressure profile.

In the invention, the control unit is designed as a process-controlled sequence control, so that an operation of the packaging machine can be perfectly adapted to the respective actual measured variables is. Using the current pressure profile detectable by the sensor system and transmitted to the control unit, the control unit can optionally determine the filling level and / or volume flow based on a comparison of the pressure profile with a reference pressure profile provided for the manufacturing situation. Based on this, the control unit sets at least one process parameter of at least one further actuator of the packaging machine. From the input signals of the control device depicting the pressure curve, process parameters (control signals) are formed as output signals in accordance with a control algorithm for performing the aforementioned comparison, which via actuators to a control object (technological process, control path) provided on the packaging machine, for example to at least one work process on the Sealing station, act.

Figur 1

eine schematische Ansicht einer bekannten Siegelstation;

Figur 2

eine Verpackungsmaschine, die in Form einer Tiefziehverpackungsmaschine ausgebildet ist, an welcher die Erfindung zum Einsatz kommen kann;

Figur 3

eine schematische Darstellung der Siegelstation aus Figur 2 mit verbundener Steuereinheit; und

Figur 4

eine schematische Darstellung eines ausführungsgemäßen Verfahrens.

In the following, the prior art and embodiments of the invention are explained in more detail with reference to the figures. Show:

Figure 1

a schematic view of a known sealing station;

Figure 2

a packaging machine which is designed in the form of a thermoforming packaging machine on which the invention can be used;

Figure 3

a schematic representation of the sealing station Figure 2 with connected control unit; and

Figure 4

a schematic representation of a method according to the invention.

Fig. 1 shows a schematic representation of a sealing station S 'according to the prior art.

The sealing station S 'has an upper sealing tool part SO' and a lower sealing tool part SU 'which can be closed with the upper sealing tool part SO' and which is designed to receive preformed packaging trays VM '. In the in Fig. 1 Packaging trays VM 'shown are packaging contents I', ie products, added whose degrees of filling FG 'are different.

In Figure 1 the sealing station S 'forms a sealing chamber SK', in which the packaging trays VM 'together with an upper film O' positioned above it enclose an airtight packaging volume P ', which consists of a partial volume V1' and a partial volume V2 '. The partial volume V1 'is composed of the sum of the respective packaging tray volumes created by the packaging trays VM' and released by the products. The partial volume V2 'forms an imaginary partial volume which is enclosed between the upper film O' and an imaginary plane E 'shown in dashed lines. Based on the partial volume V2 ' A connecting gap SP 'is formed above the packaging troughs VM', which, in particular during the filling process, allows the gas G 'to be distributed within the entire packaging volume P'.

According to Fig. 1 A sealing tool SW, for example a height-adjustable sealing frame, is positioned within the sealing tool upper part SO 'for a sealing process, which is designed to move the upper film O' for the sealing process in the direction of the packaging trays VM 'provided below by means of a lifting movement H'.

At the in Fig. 1 The embodiment shown is initially the packing volume P ', consisting of the sum of the respective partial volumes V1', V2 ', filled to a preset gas pressure with a gas G' to create a desired atmosphere. The gassing pressure is conventionally generated from a difference between a target gassing pressure of finished packaging and a preset gas offset pressure. By means of the subsequent stroke movement H ', the sealing tool SW' pushes the amount of gas contained in the partial volume V2 'into the partial volume V1' released by the product contents I 'within the packaging trays VM', so that, assuming a homogeneous level distribution, ie not in itself varying fill levels, in the finished packaging the target gas pressure can be set.

As already stated at the previous point in the introduction to the description, the respective fill levels of the provided packaging can vary, so that the above offset approach, which, contrary to actual circumstances, is based on the assumption of a homogeneous fill level distribution, leads to the production of visually different packaging.

Fig. 2 shows a schematic view of a packaging machine 1, which is designed in the form of a thermoforming packaging machine T. The packaging machine 1 has a forming station 2, a sealing station 3, a cross-cutting device 4 and a longitudinal cutting device 5. These are arranged in this order in a working direction R on a machine frame 6.

A feed roller 7 is arranged on the input side of the machine frame 6 of the packaging machine 1, from which a lower film U is pulled off as the lower packaging material 8. The lower film U is transported into the forming station 2 by means of a feed device (not shown). By means of a deep-drawing process taking place there, packaging trays 14 are formed in the lower film U by means of the forming station 2. The packaging trays 14 are then transported on to an insertion section 15, where they are manually or automatically with a product 16 can be filled. Following the insertion section 15, the packaging trays 14 filled with the products 16 are transported on to the sealing station 3. By means of the sealing station 3, the packaging trays 14 can be sealed with an upper film O, which forms an upper packaging material 10, so that by sealing the upper film O onto the packaging trays 14, closed packs V are produced, which by means of the cross-cutting device 4 and the longitudinal cutting device 5 can be isolated and removed by means of a discharge device 13. It may be that empty packaging LV is included in the conveyed goods, for example because of an interruption in the product preparation process.

Furthermore, the in Fig. 2 shown packaging machine 1 via a control terminal 9, on which process parameters can be set for the respective workstations provided on the packaging machine 1. The operating terminal 9 comprises a control unit 11, shown only schematically. The control unit 11 is configured to perform arithmetic operations, in particular in real time during the manufacturing process, in order to control the packaging machine on a process-based basis, i.e., if necessary, to initiate an adjustment of the respective process parameters of the packaging machine based on the process .

The control unit 11 is equipped with a sensor system 12 for detecting a pressure P _IST (see FIG Fig. 3 ) one within the sealing station 3 according to Fig. 3 formed packing volume P connected. On the basis of the sensor system 12, the control unit 11 can continuously be transmitted current pressure values during the manufacturing process, that is to say the respective pressure curves, during the gassing and / or evacuation process.

Also shows Fig. 2 that the control unit 11 is connected to a schematically illustrated memory 17 so that it can access reference values stored thereon for generating process parameters, in particular for adapting such parameters. For example, it can compare the pressure profile recorded as an input variable at the sealing station 3 by means of the sensor system 12 with a corresponding reference pressure profile of the memory 17, optionally determining a degree of filling and / or a volume flow in a first step using an algorithm and then in a further step is generated based on at least one process parameter as an output variable, on the basis of which the manufacturing process can be adapted, so that the packaging machine 1 is able to optimally adapt the manufacturing process running on it to the respective filling states.

Fig. 3 shows the sealing station 3 of in Fig. 2 shown packaging machine 1 in isolated representation.

The sealing station 3 comprises an upper sealing tool part 20 and a lower sealing tool part 21, which enclose a sealing chamber 23. Fig. 3 further shows that two packaging trays 14 with respective products 16 are received in the sealing tool lower part 21, their respective degrees of filling 22 differing.

The packaging trays 14 received within the sealing station 3, together with the upper film O arranged above, enclose a packaging volume P. The packing volume P is traversed by means of an imaginary plane E shown in dashed lines, as a result of which it is divided into a partial volume V1 and a partial volume V2. The packaging tray 14, which is present on the right with a lower degree of filling 22 when viewed in the image plane, forms a larger proportion of the packaging volume P than the other packaging tray 14, shown to the left with a greater degree of filling 22.

According to Fig. 3 the partial volume V2 enclosed by the upper film O and the imaginary plane E as well as the partial volume V1 (free package volume P) provided within the packaging trays 14 can be filled with a gas G via a line 26 and gas pins 29 provided thereon. A gas source Q is provided for the gas supply. An evacuation process can be controlled by means of a (vacuum) pump VP. For the filling process and the evacuation process, valves 27a, 27b are formed in the line 26, which can be controlled in particular in a process-controlled manner, for example on the basis of recorded pressure values.

A pressure sensor 18 is connected to the line 26 as a sensor system 12 for detecting the pressure P _{ACTUAL within the package volume P.} The pressure sensor 18 is functionally connected to the control unit 11, which is configured to further calculate the _{pressure P IST transmitted to it as an input variable.} In particular, the control unit 11 is able to determine the pressure _profile present on the basis of the detected pressure values P IST during the filling of the package volume P and to compare this, possibly a section thereof, with a preset reference pressure profile in order to use an algorithm, for example to calculate a degree of filling and / or a volume flow with respect to the packaging V positioned within the sealing station 3, on which the control unit 11 generates at least one process parameter PP as an output variable.

To the line 26 is according to Figure 3 a collection volume is connected, which can be used to calculate the packing volume P. Also shows Figure 3 a feed line section 30, the volume of which can be subtracted when calculating the degree of filling 22.

Fig. 4 shows a method in a schematic representation.

First of all, in a first process step A, the free packing volume P is filled with a gas G via the line 26 to create a desired atmosphere.

During the filling according to step A, according to method step B, pressure is detected by means of the sensor system 12 within the package volume P. As a result, a time-dependent pressure curve 27 for the pressure P _ACT that is present within the package volume P between an outlet pressure P1 up to a predetermined gassing pressure P2 can be recorded. In this case, the control unit 11 can be configured to take into account only a section of the pressure curve 27 for the further method.

According to Fig. 4 the pressure curve 27 recorded in method step B is a linear pressure curve K _IST .

According to the further method step C, a comparison VG of the recorded pressure profile 27 with a reference pressure profile 28 takes place. The control unit 11 retrieves the reference pressure profile 28 from the memory 17 for the comparison VG. The control unit 11 can be designed to call up a suitable reference pressure curve 28 from a large number of reference pressure curves 28 provided on the memory 17 with regard to at least one process parameter predetermined on the packaging machine 1, in particular at the sealing station 3, for the manufacturing process. According to the reference pressure curve 28, a time-dependent reference _{pressure curve K REF is} shown, which would arise in particular when gassing empty packaging LV used for the manufacturing process. In order to carry out a meaningful comparison and an appropriate derivation of the degree of filling 22, it is advantageous to assume the same volume flow for the respective pressure curves 27, 28.

After performing method step C, that is, after comparing the respective gradients of the pressure curve 27 and the reference pressure curve 28, the degree of filling 22 and / or the volume flow V is determined in accordance with the optional, subsequent method step D. This is based in particular on the respective time segments t and t * that have elapsed for the pressure curve 27 and for the reference pressure curve 28, based on the packing volume P and the respective pressure levels P1, P2.

The calculated degree of filling 22 and / or volume flow V can be used in a further method step E by the control unit 11 to calculate at least one process parameter PP. For example, the control unit 11 calculates an offset pressure P _OFF , a gas velocity V _GAS , a valve setting value x and / or triggers a malfunction display y based thereon. However, it is also conceivable that the process parameters can be set directly on the basis of the Comparison between the recorded pressure curve (27) and the reference pressure curve (27) can be set.

On the basis of the offset _{pressure P OFF} , the control unit 11 can calculate a pressure P _RED , up to which the filling process A is controlled, in _{view of a desired gassing target pressure P SOLL of finished packaging V.} This is shown schematically in Figure 4 shown by the dashed line EZ.

The principle according to the invention can be excellently applied in a process-controlled packaging machine in which the respective work processes run based on measurement signals, so that, considered in total, both optimal process times and higher quality products can be produced.

Claims (11)

1. A method of operating a sealing station (3) of a packaging machine (1) for producing, in the case of possibly varying filling degrees (22), packages (V) with at least substantially similar package appearances, the method comprising the following steps:

   • filling (A) a free package volume (P) enclosed between a lower and an upper packaging material (8, 10) and defined by at least one package (V) positioned within the sealing station (3) with a gas (G), intended to be used for creating a desired atmosphere, from an initial pressure (P1) prevailing in the package volume (P) up to a predetermined gas flushing pressure (P2),

   • detecting (B), at least temporarily during filling (A) of the package volume (P), a pressure curve (27) by means of at least one pressure-detecting sensor system (12) connected to the package volume (P), the pressure curve (27) being preferably detected on the basis of a time-dependent pressure curve (K_IST) between the initial pressure (P1) and the predetermined gas flushing pressure (P2),

   • comparing (C) the detected pressure curve (27) with a reference pressure curve (28) detected preferably on the basis of a pressure curve (K_REF), which, in turn, is time-dependent, for filling a known free reference package volume (P_REF) of at least one, in particular empty reference package (V_REF) positioned within the sealing station (3) with the gas (G) between the initial pressure (P1) and the predetermined gas flushing pressure (P2),

   • setting (E) at least one process parameter (PP) at the packaging machine (1) with due regard to the comparing of the detected pressure curve (27) with the reference pressure curve (28).
2. The method according to claim 1, characterized in that the setting of the at least one process parameter (PP) is carried out in real time per machine cycle and that, based on this, an automated adaptation of the process parameter (PP) is executed.
3. The method according to one of the preceding claims, characterized in that the process parameter (PP) is an offset pressure (P_OFF) used during the filling process and/or during at least one subsequent filling process (A), so as to fill the package volume (P) with gas (G) only until a pressure (P_RED) is reached, which results from a gas flushing target pressure (P_SOLL) for finished packages (V) minus the calculated offset pressure (P_OFF).
4. The method according to claim 3, characterized in that for calculating the offset pressure (P_OFF) the Boyle-Mariotte law is used, taking into account a partial volume (V2) of the package volume (P) displaced by a sealing stroke (H) and a free package volume (V1), which can be determined in the light of the calculated filling degree (22), including the gas flushing target pressure (P_SOLL) of finished packages (V) to be generated in said free package volume.
5. The method according to one of the preceding claims, characterized in that the process parameter (PP) is a gas velocity (V_GAS) reached at respective gas pins (29) configured for filling the package volume (P).
6. The method according to one of the preceding claims, characterized in that the process parameter (PP) is a valve setting value (x) which influences an evacuating process and/or the gas flushing process.
7. The method according to one of the preceding claims, characterized in that the process parameter (PP) triggers a malfunction indicator (y) at the packaging machine (1).
8. The method according to one of the preceding claims, characterized in that the free package volume (P) is connected to a collecting volume (AV) of known size and that the free package volume (P) is calculated on the basis of a detected pressure compensation.
9. The method according to one of the preceding claims, characterized in that the process parameter (PP) is continuously adjusted in the light of averaged values of the filling degree (22) and/or of the volume flow (V).
10. The method according to one of the preceding claims, characterized in that the package volume (P) filled with gas (G) is formed such that a pressure compensation between a plurality of packages (V) positioned within the sealing station (3) will take place during the sealing stroke (H).
11. A packaging machine (1) for producing, in the case of possibly varying filling degrees (22), packages (V) with at least substantially similar package appearances, comprising a sealing station (3) and a control unit (11), which is functionally connected to a sensor system (12) formed at the sealing station (3) and used for detecting a pressure (P_IST) of a package volume (P) provided within the sealing station (3), characterized in that the control unit (11) is configured for conducting a comparison (C) between a time-dependent pressure curve (27), which is detected between predetermined pressure levels (P1, P2) at least temporarily during a filling process (A) of the package volume (P) enclosed within the sealing station (3), and a time-dependent reference pressure curve (28) representative of the filling process (A) of a known reference volume (V_REF) and stored in the control unit (11) between the predetermined pressure levels (P1, P2), the control unit (11) being further configured for setting at least one process parameter (PP) at the packaging machine (1) with due regard to the comparison of the detected pressure curve (27) with the reference pressure curve (28).

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