Filling level-independent gassing

Abstract

A method for operating a sealing station of a packaging machine, wherein the method may include one or more of the following steps: filling a packing volume of a package with a gas to create a desired atmosphere to a preset gassing target pressure for a finished package, wherein the packaging volume may be defined by a lower and an upper packaging material; discharging a partial amount of the gas introduced into the packaging volume from the packaging volume into a collection volume while retaining the packaging volume generated by the preceding filling, which reduces the pressure within the packaging volume; and reducing the packaging volume by moving the upper packaging material to an end position that corresponds to a desired appearance such that the pressure inside the package increases again to near the gassing target pressure. A sealing station that performs this method is also described.

Claims

1. A method for operating a sealing station of a packaging machine for producing packages with packaging appearances being at least essentially similar to one another even if the packages have varying filling degrees, the method comprising the following steps: filling a packaging volume of at least one package positioned inside a sealing station by introducing an amount of gas to a preset gassing target pressure for a finished package to create a desired atmosphere, wherein the packaging volume is enclosed between a lower packaging material and an upper packaging material; discharging a partial amount of the amount of gas introduced into the packaging volume from the packaging volume into a collection volume in fluid communication with the packaging volume while maintaining the packaging volume generated by the preceding filling step so that completion of the discharging step creates an intermediate pressure inside the packaging volume, wherein the intermediate pressure is less than the gassing target pressure, and wherein a channel puts the packaging volume into fluid communication with the collection volume; wherein the discharged partial amount of gas substantially equals an amount of the gas received within a theoretical partial volume of the packaging volume, wherein the theoretical partial volume is defined at least partially by a theoretical plane, which crosses the packaging volume and occupies an edge of the lower packaging material, and by the upper packaging material; and reducing the packaging volume by the theoretical partial volume by moving the upper packaging material to an end position that substantially overlies the theoretical plane so that a final pressure inside the at least one package is substantially the gassing target pressure.

2. The method according to claim 1, wherein the discharging the partial amount step comprises discharging the partial amount of gas through the channel into the collection volume and wherein the collection volume is at least partially defined by at least one of a tool upper part of the sealing station and the upper packaging material.

3. The method according to claim 1, wherein the discharging the partial amount step comprises discharging the partial amount of gas through the channel into the collection volume and wherein the collection volume is a separate collection container.

4. The method according to claim 1, further comprising determining a target pressure of the collection volume using the discharged partial amount of gas, and keeping open the channel until a pressure inside the collection volume reaches the target pressure of the collection volume.

5. The method according claim 4, wherein the pressure generated inside the collection volume created by the discharged partial amount of gas remains lower than the intermediate pressure within the packaging volume to maintain the packaging volume during the discharge process.

6. The method according to claim 1, wherein the upper packaging material is moved into the end position using one of an aeration process or at least one device executing a lifting movement.

7. The method according to claim 1, wherein the upper packaging material is sealed with the lower packaging material at the end position.

8. The method according to claim 1, further comprising evacuating the packaging volume prior to the step of filling the packaging volume of the at least one package positioned inside the sealing station by introducing the amount of gas to the preset gassing target pressure for the finished package.

9. The method according to claim 1, further comprising the step of determining at least one of the theoretical partial volume and the collection volume using a test run of the sealing station.

10. The method according to claim 1, wherein the method is used in the production of packages having a predetermined filling degree which remains approximately the same, and further comprising determining an offset pressure from a difference between the gassing target pressure and the intermediate pressure which is still present within the packaging volume after the partial amount of the gas has been discharged from the packaging volume, and introducing a second amount of gas into a packaging volume of at least one other package positioned inside the sealing station in a subsequent machine cycle, wherein the second amount of gas is based on the difference between the gassing target pressure and the intermediate pressure.

11. A method for operating a sealing station of a packaging machine for producing packages with packaging appearances being at least similar to one another even if the packages have varying filling degrees, the method comprising the following steps: filling a packaging volume, enclosed between a lower packaging material and an upper packaging material, of at least one package positioned inside the sealing station, with a gas intended for creating a desired atmosphere to a preset gassing target pressure for a finished package; discharging a partial amount of the gas introduced into the packaging volume from the packaging volume via a channel connected thereto into a collection volume linked thereto while retaining the packaging volume generated by the preceding filling so that inside the packaging volume, a pressure reduction relative to the gassing target pressure occurs for a remaining residual amount of the filled gas; wherein the discharged partial amount of the gas substantially corresponds to an amount of the gas received within a theoretical partial volume of the packaging volume, which theoretical partial volume is at least partially defined by a theoretical plane, which crosses the packaging volume and which occupies an edge of the lower packaging material, and by the upper packaging material; and reducing the packaging volume by the theoretical partial volume while moving the upper packaging material to an end position essentially falling to the theoretical plane so that pressure inside the at least one package increases again to the gassing target pressure.

12. The method according to claim 11, wherein the collection volume is at least partially defined by at least one of a tool upper part of the sealing station or the upper packaging material.

13. The method according to claim 11, wherein the collection volume is a collection container that is separate from an upper tool part and a lower tool part of the sealing station.

14. The method according to claim 11, further comprising determining a target pressure of the collection volume using the discharged partial amount of the gas, and keeping open the channel until a pressure inside the collection volume reaches the target pressure of the collection volume.

15. The method according claim 11, wherein a pressure generated inside the collection volume created by the discharged partial amount of the gas remains lower than a pressure within the packaging volume during the discharge process to retain the packaging volume during the discharge process.

16. The method according to claim 11, wherein the upper packaging material is moved into the end position using one of an aeration process or at least one device executing a lifting movement.

17. The method according to claim 11, wherein the upper packaging material is sealed with the lower packaging material at the end position.

18. The method according to claim 11, further comprising evacuating the packaging volume prior to the step of filling the packaging volume.

19. The method according to claim 11, further comprising determining at least one of the theoretical partial volume or the collection volume using a test run of the sealing station.

Description

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) In the following, an advantageous embodiment of the present invention will be explained in more detail making reference to a drawing, in which the individual figures show:

(2) FIG. 1 is a schematic sectional drawing of a known embodiment of a sealing station without a gas discharge capability;

(3) FIG. 2 is a schematic side view of one embodiment of a packaging machine in accordance with the teachings of the present disclosure, which is configured in the form of a deep-drawing packaging machine and comprises a sealing station with one embodiment of a gas discharge function according to the teachings of the present disclosure;

(4) FIG. 3 is a schematic sectional drawing of one embodiment of a sealing station in accordance with the teachings of the present disclosure;

(5) FIG. 4 is a schematic sectional drawing of one embodiment of a sealing station in accordance with the teachings of the present disclosure showing a collection volume formed by a separate collection container; and

(6) FIG. 5 is a schematic drawing showing the principles and sequencing of one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(7) The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.

(8) The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

(9) FIG. 1 shows a schematic presentation of a sealing station 3′ according to the prior state of the art.

(10) The sealing station 3′ has a tool upper part 20′ and a tool lower part 21′ which can be moved up to the tool upper part 20′ using a lifting movement and which is configured to accommodate pre-formed packaging troughs 14′. In the packaging troughs 14′ shown in FIG. 1, products 16′ with different filling degrees 22′ are accommodated.

(11) Inside the sealing station 3′, the packaging troughs 14′ together with an upper film 10′ 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 trough volumes created by the packaging troughs 14′ and released by the products 16′. The partial volume V2′ forms a theoretical partial volume, which is enclosed between the upper film 10′ and a theoretical plane E′ which is represented by a dotted line. Based on the partial volume V2′, a connecting gap S′ is formed above the two packaging troughs 14′, which allows the gas to be distributed within the packaging volume P′, particularly during the filling process.

(12) According to FIG. 1, a sealing unit 25′ for a sealing process is positioned inside the tool upper part 20′, which is configured to move the upper film 10′ for a sealing process in the direction of the packaging troughs 14′ positioned below using a lifting movement H′.

(13) In the embodiment shown in FIG. 1, the packaging volume P′, consisting of the sum of the respective partial volumes V1′ and V2′, is initially filled to a gassing target pressure p.sub.soll′ with a gas to create a desired atmosphere. By the subsequent lifting movement H′ of the sealing unit 25′, the gas amount contained in the partial volume V2′ is pressed into the partial volume V1′ released by the products 16′ within the packaging troughs 14′. Since the respective filling degrees 22′ of the packaging troughs 14′ are different, the final pressure inside the finished packages V is also different. This leads to the fact that packages V cannot be produced with packaging appearances which are at least essentially similar to one another.

(14) FIG. 2 shows a schematic view of a packaging machine 1 of the present invention, which is configured in the form of a deep-drawing packaging machine T. The packaging machine 1 has a forming station 2, a sealing station 3, a cross cutting device 4 as well as a longitudinal cutting device 5. These are arranged in this order in a working direction R on a machine frame 6.

(15) On the machine frame 6 of the packaging machine 1, a feed roller 7 is arranged on the input side, from which a lower film U is drawn off as the lower packaging material 8. The lower film U is transported into the forming station 2 using a feed device which is not shown. Using a deep-drawing process taking place there, packaging troughs 14 are formed into the lower film U using the forming station 2. The packaging troughs 14 are then further transported to an infeeding stretch 15, where they can be filled manually or automatically with a product 16. Following the infeeding stretch 15, the packaging troughs 14 filled with the products 16 are further transported to the sealing station 3. Using the sealing station 3, the packaging troughs 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 troughs 14, sealed packages V are produced, which can be separated with the cross cutting device 4 and the longitudinal cutting device 5 and transported away using a discharge device 13.

(16) FIG. 3 schematically shows a sealing station 3 according to the invention as it can be used on the packaging machine 1 shown in FIG. 2.

(17) The sealing station 3 according to the invention includes a tool upper part 20 as well as a tool lower part 21, which enclose a sealing chamber 23. FIG. 3 further shows that two packaging troughs 14 with respective products 16 are accommodated in the tool lower part 21, whereby the respective filling degrees 22 of the packaging troughs 14 differ.

(18) The packaging troughs 14 accommodated inside the sealing station 3, together with the upper film O arranged above them, enclose a packaging volume P. The packaging volume P is traversed using a theoretical plane E represented by a dotted line, whereby it is divided into a partial volume V1 and a partial volume V2. The packaging trough 14 on the right viewed at image plane with a lower filling degree 22 forms a larger proportion of the packaging volume P than the other packaging trough 14 filled with a higher filling degree 22.

(19) According to FIG. 3, the partial volume V2 enclosed by the upper film O and the theoretical plane E is connected via a channel 26 to a collection volume V3 integrated in the tool upper part 20, which is enclosed between the tool upper part 20 and the upper film O.

(20) According to FIG. 3, the packaging volume P is filled with a gas G via a section 26a of the channel 26 to create a desired atmosphere at a gassing target pressure p.sub.soll. For the filling process, section 26a comprises an inlet valve 37a controlled by a pressure sensor 38a. The pressure sensor 38a is configured to detect the pressure level within the packaging volume P.

(21) Subsequently to this, a partial amount TM (see FIG. 5) contained within the partial volume V2 of the gas G brought to the gassing target pressure p.sub.soll is again taken from the packaging volume P via the channel 26. Thereby, the gas G is led into the collection volume V3 via sections 26a, 26b, and 26c of the channel 26. The partial amount TM of the discharged gas G corresponds to the amount of the gas contained in the partial volume V2. For the discharge process, section 26b comprises a (discharge) valve 27 controllable by another pressure sensor 48a. The pressure sensor 48a is configured to detect the pressure level within the collection volume V3.

(22) Section 26c is simultaneously provided as an aeration channel with an aeration valve 47a.

(23) Due to the discharging of the partial amount TM, the amount of gas originally introduced during the preceding filling process is reduced to a residual amount RM of the gas G which is shown below in connection with FIG. 5 and which remains in the packaging volume P, whereby the initially prevailing gassing target pressure p.sub.soll decreases to a lower pressure level pred.

(24) After the discharged partial amount TM of the gas G has been taken up by the collection volume V3, the packaging volume P, i.e. the valve 27 of the discharge channel 26, is closed and the upper film O is pressed in the direction of the packaging troughs 14 positioned below using the sealing unit 25. The upper film O is brought into an end position L positioned according to the theoretical plane E, in which the upper film O is sealed onto the packaging troughs 14.

(25) Due to the lowering of the upper film O, the gas G contained in the partial volume V2 is pressed into the partial volume V1. As a result, the reduced pressure p.sub.red set within the packaging volume P during the discharge process increases again to the gassing target pressure p.sub.soll.

(26) Lowering of the upper film O can be controlled in such a slow manner using the sealing unit 25, in particular a device 28 which can be lowered on it and is formed plate-like, and/or using an aeration process so that the remaining amount RM contained within the packaging volume P is distributed slowly over the respective packages V. The device 28 is configured as a product protection plate and is configured to prevent unwanted heat from being transferred to the products 16 accommodated inside the packaging troughs 14 during the sealing process.

(27) FIG. 4 shows the sealing station 3 according to FIG. 3, whereby a separate collection container 30 is used as collection volume V3. In addition, a separate aeration channel 26d is connected to the sealing chamber 23, which comprises an aeration valve 47b.

(28) In FIGS. 3 and 4, the channel 26 in its section 26b comprises the valve 27, which is opened for the discharge process so that the partial amount TM of the gas G can flow from the packaging volume P into the collection volume V3. Insofar as using the section 26a filling of the packaging volume P or using the section 26c aeration of the sealing chamber 23 takes place, the valve 27 remains closed. In addition, the valve 27 remains closed when an evacuation of the packaging volume P takes place prior to the filling process.

(29) The discharge process via the valve 27 according to FIG. 4 can be controlled using a pressure sensor 48b connected to the collection volume V3. The filling process takes place via an inlet valve 37b which is pressure-controlled using a pressure sensor 38b connected to the packaging volume P.

(30) For further transport of sealed packages V out of the sealing station 3, the tool upper part 20 is aerated via section 26c of FIG. 3 or via the separate aeration channel 26d of FIG. 4 (i.e. creating a pressure equalization to the atmospheric pressure of the environment).

(31) FIG. 5 shows the principle of the method according to the invention.

(32) In a first method step, the packaging volume P is filled with the desired gas G to the gassing target pressure p.sub.soll. There is then a predetermined amount of gas GM in the packaging volume P corresponding to the gassing target pressure p.sub.soll.

(33) In the second and third method steps, the gas amount (partial amount TM) contained within the theoretical partial volume V2, which is present above the theoretical plane E drawn in as the system boundary, is discharged via the channel 26 shown in FIGS. 3 and 4.

(34) Accordingly, according to the fourth method step, the residual amount RM of the gas G remaining within the packaging volume P is distributed over the entire packaging volume P so that a reduced pressure level p.sub.red is applied within the maintained packaging volume P.

(35) Finally, in the fifth method step, the packaging volume P is reduced by the theoretical partial volume V2 by pressing the upper packaging material down into the end position L, which drops to the theoretical level E. The gassing target pressure p.sub.soll within the partial volume V1 intended for finished packaging V is now present again. According to this process, packaging with packaging appearances being at least essentially similar to one another can be produced irrespective of the filling degree.

(36) As the basis for the method according to the invention it is assumed that the sum of the theoretical partial volume V2 with the collection volume V3 is geometrically known.

(37) Using a test run which can be carried out using the sealing station 3 according to the invention, the ratio of the partial volume V2 and the collection volume V3 can be determined. The test run could, for example, be carried out in such a way that the lower film U used for the packaging troughs 14 is not inserted into the sealing station 3 in a shaped form and is fixed there together with the upper film O. During gassing, therefore, only the partial volume V2 is gassed to the gassing target pressure p.sub.soll. If the channel 26 is then opened and left open until a pressure equalization between the partial volume V2 and the collection volume V3 has been reached, the ratio of the partial volume V2 to the collection volume V3 can be calculated using the pressure that occurs. Via the total volume, consisting of the partial volume V2 and the collection volume V3, the respective volumes of the partial volume V2 and the collection volume V3 can be directly calculated.

(38) Alternatively, the partial volume V2 could also be estimated approximately via an executed lifting of the sealing unit 25. Further alternatively, the respective volumes V2 and V3 could also be calculated using clearly known reference volumes when commissioning the machine. The volumes used in connection with the principle according to the invention, that is, the partial volume V2 as well as the collection volume V3, can be conveniently stored in a tool database of the packaging machine 1 and serve as calculation variables during the packaging process.

(39) Insofar as a constant filling degree of the packages V to be closed is expected, for example, because the same intersection of a selected product 16, for example sliced sausage or sliced cheese, is always present in the respective packaging troughs, the principle according to the invention can be used for the automated generation of an offset pressure so that the discharge process of the partial amount of the gas can be dispensed with by using the offset pressure, in order to produce packages with essentially constant packaging appearances.

(40) Thereby, it is only gassed to a reduced pressure, which results from the gassing target pressure less the offset pressure calculated on the basis of the invention, and sealed immediately afterwards. In order to check the correctness of the offset pressure, it could be provided that this is calculated several times during a product batch repeatedly using the principle according to the invention.

(41) The invention could just as easily be carried out at a sealing station which is part of a packaging machine which is not configured as a deep-drawing packaging machine, for example a tray sealing machine with feeding of pre-fabricated packaging trays.

(42) From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting.

(43) The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention.

(44) As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.