METHOD AND MACHINES FOR FILLING FLEXIBLE TUBULAR-BAG PACKAGES

Abstract

The invention relates to a tubular-bag machine and to a method for continuous or intermittent production of tubular-bag packages (02) which are filled with a product (03) in a tubular-bag machine (01) of this kind, the tubular-bag machine (01) comprising a screw-type metering device (10) in which a metering screw (OS) can be driven to rotate relative to a metering tube (06) for metering the product (03), and a compactor (07) by means of which the product (03) can be compacted by applying a vacuum and sucking out gas being provided ahead of, behind or within the metering tube (06), the compactor (07) comprising a suction bushing which is permeable to gas through fine pores and which extends coaxially with the metering tube (06), and at least part of the die suction bushing being surrounded by a vacuum chamber. By applying a vacuum, the pores of the suction bushing can be cleaned.

Claims

1. A method for continuous or intermittent production of tubular-bag packages (02) which are filled with a product (03) in a tubular-bag machine (01), the tubular-bag machine (01) comprising a screw-type metering device (10) in which a metering screw (05) can be driven to rotate relative to a metering tube (06) for metering the product (03), and a compactor (07) by means of which the product (03) can be compacted by applying a vacuum and by sucking out gas being disposed ahead of, behind or within the metering tube (06), the compactor (07) comprising a suction bushing (17) which is preamble to gas through fine pores and which extends coaxially with the metering tube (06), and at least part of the suction bushing (17) being surrounded by a vacuum chamber (20), the method comprising the following method steps, which are to be executed during a tubular-bag production process including multiple cyclically repeating work cycles: establishing a vacuum in the vacuum chamber (20) in a suctioning phase (27, 29, 30) during at least one work cycle in order to compact the product (03) by sucking out gas, establishing pressure in the vacuum chamber (20) in a blowing phase (26, 28, 33) during at least one work cycle in order to clean the pores of the suction bushing (17) by blowing out product particles that adhere to the inside of the pores during the tubular-bag production process.

2. The method according to claim 1, characterized in that the blowing phases (28, 33) are each executed after a regular number of work cycles, in particular during each work cycle.

3. The method according to claim 1, characterized in that the blowing phases are each executed after lapse of a predefined process time.

4. The method according to claim 1, characterized in that the effective vacuum during the suctioning phases (27, 29, 30) is measured using a pressure sensor (15).

5. The method according to claim 4, characterized in that the process parameters during blowing of the suction bushing (17) are changed during the blowing phases (26, 28, 33) as a function of vacuum values measured using the pressure sensor (15).

6. The method according to claim 5, characterized in that the duration of the blowing phases (26, 28) is changed as a function of the vacuum values measured using the pressure sensor (15).

7. The method according to claim 5, characterized in that the pressure level in the blowing phases is changed as a function of the vacuum values measured using the pressure sensor (15).

8. The method according to claim 5, characterized in that the blowing phases (26) are triggered as a function of a vacuum value (25) measured using the pressure sensor (15).

9. The method according to claim 8, characterized in that the effective vacuum during a suctioning phase executed using a cleaned suction bushing is measured using a pressure sensor and is stored as an initial vacuum value (22), a limit value (23) for triggering the blowing phases being determined as a function of the initial vacuum value.

10. The method according to claim 1, characterized in that the tubular-bag production process is interrupted or an error is reported if the vacuum pressure during the suctioning phases (27, 29, 30) measured using the pressure sensor (15) exceeds a predefined limit value (30).

11. A tubular-bag machine (01) for continuous or intermittent production of tubular-bag packages (02) which are filled with a product (03), comprising a metering device (10) in which a metering screw (05) can be driven to rotate relative to a metering tube (06) for metering the product (03), a compactor (07) by means of which the product (03) can be compacted by applying a vacuum and by sucking out gas being provided ahead of, behind or within the metering tube (06), and the compactor (07) comprising a suction bushing (17) which is permeable to gas through fine pores and which extends coaxially with the metering tube (06), and at least part of the suction bushing (17) being surrounded by a vacuum chamber (20), and the vacuum chamber (20) being connectable to a vacuum source (12), and the compactor (07) being controlled by a controller (14) as a function of the tubular-bag production process (14) so as to establish a vacuum in the vacuum chamber (20) in suctioning phases (27, 29, 30) as a function of the process and to compact the product (03) by sucking out gas, characterized in that the vacuum chamber (20) can selectively also be connected to a pressure source (11), the compactor (07) being controlled by the controller (14) as a function of the tubular-bag production process so as to establish a vacuum in the vacuum chamber (20) in blowing phases (26, 28, 33) as a function of the process, the pores of the suction bushing (17) being cleanable during the blowing phases (26, 28, 33) by blowing out product particles that adhere to the inside of the pores during the tubular-bag production process.

12. The tubular-bag machine according to claim 11, characterized in that the effective vacuum in the vacuum chamber (20) and/or in the vacuum lines (16) can be measured using a pressure sensor (15).

13. The tubular-bag machine according to claim 11, characterized in that the metering device (10) comprises a metering screw (05) with an associated metering tube (06) which are disposed immediately above the sealing jaws (08) for sealing the tubular-bag packages (03).

14. The tubular-bag machine according to claim 11, characterized in that the screw-type metering device is configured in the manner of a feeding screw which is disposed in front of a storage tank (04) for intermediate storage of the product.

Description

[0026] FIG. 1 shows a side view of a schematically illustrated tubular-bag machine having a compactor;

[0027] FIG. 2 shows a cross-section of the compactor of the tubular-bag machine of FIG. 1;

[0028] FIG. 3 shows a perspective side view of the compactor of FIG. 2;

[0029] FIG. 4 shows a time diagram of the process parameters of a first method for cleaning the compactor of FIG. 2;

[0030] FIG. 5 shows a time diagram of the process parameters of a second method for cleaning the compactor of FIG. 2;

[0031] FIG. 6 shows a time diagram of the process parameters of a third method for cleaning the compactor of FIG. 2;

[0032] FIG. 7 shows a time diagram of the process parameters of a fourth method for cleaning the compactor of FIG. 2.

[0033] FIG. 1 shows a schematic side view of a tubular-bag machine 01 for producing tubular-bag packages 02. In FIG. 1, the tubular-bag machine 01 is illustrated only with the components that are necessary for understanding the invention. For filling the tubular-bag packages 02 with the grainy or fine-grained product 03, the latter is first fed into a storage tank 04 and then fed in metered amounts from the storage tank 04 into the tubular-bag packages 02 by a metering screw 05 being driven to rotate. A compactor 07 by means of which air or inert gas can be sucked from the product to be discharged at the end of the metering tube 06 is located at the lower end of the metering tube 06. Sucking the air or inert gas from the product at the end of the metering tube 06 prevents the product from trickling in an uncontrolled manner into the space between the sealing jaws 08 by means of which the tubular-bag packages 02 are sealed. The drive 09, the storage tank 04, the metering screw 05 and the metering tube 06 form the main components of the metering device 10 in the tubular-bag machine 01.

[0034] The compactor 07 can be selectively connected to a pressure source 11 and to a vacuum source 12. A switching valve 13 controlled by a controller 14 is provided for switching between the pressure source 11 and the vacuum source 12. The controller 14 for controlling the pressure supply at the compactor 07 can of course also be integrated in the main controller of the tubular-bag machine 01.

[0035] At the compactor 07, there is a pressure sensor 15 by means of which the vacuum effective at the compactor 07 during operation of the compactor 07 can be measured. The pressure sensor can alternatively also be disposed on one of the pressure lines. The data of the pressure sensor 15 is transmitted to the controller 14 via a data line. Also, the controller 14 is connected to the drive 09 via a data line. In this way, the operating state can be transmitted to the controller 14 as the metering screw 05 is being driven. The pressure from the pressure source 11 and the vacuum from the vacuum source 12 are transferred to the compactor 07 via a pressure line 16 starting from the switching valve 13.

[0036] FIG. 2 shows the compactor 07 including the pressure sensor 15 and the pressure line 16 in an enlarged sectional view. The compactor 07 is located at the lower end of the metering tube 06, in which the metering screw 05 for metering the products 03 can be driven to rotate. In FIG. 2, the metering tube 06 is illustrated in the unfilled state in order to facilitate understanding of the compacting device 07.

[0037] In the compactor 07, a suction bushing 17 for sucking gas from the product to be conveyed by the metering screw 05 is provided. The suction bushing 17 is composed of a perforated support plate 18 on which the fine-pored filter mat 19 rests. At its outside, the suction bushing 17 is surrounded by a vacuum chamber 20 which can be selectively subjected to pressure or to vacuum via the pressure line 16. When the vacuum chamber 20 is subjected to a vacuum, the gas is sucked out of the product conveyed by the screw 05 through the pores of the filter mat 19 into the vacuum chamber 20, whereby the product is compacted in the desired manner. If the vacuum chamber 20 is then subjected to pressure in another work cycle, the gas flows in the opposite direction through the pores of the filter mat 19, the product particles adhering to the inside of the pores thus being blown out. In this way, the desired cleaning effect for cleaning the suction bushing 17 is achieved.

[0038] FIG. 3 shows the lower end of the suction tube 06, the metering screw 05, the compactor 07 including the pressure sensor 15 and the pressure line 16, and a product die 21 in a combined perspective illustration.

[0039] In a time diagram, FIG. 4 shows a first method for cleaning the compactor 07 by blowing as per the invention. FIG. 4 illustrates the flow of a tubular-bag production process in a window of three work cycles, the individual work cycles being separated from each other by dashed vertical lines. In the upper part of FIG. 4, the speed of rotation of the metering screw 05 during the individual work cycles is marked out. As is visible, the metering screw stands still up to time t1 and is then driven at a constant speed of rotation by the drive 09 for a predefined process time so as to feed a specific amount of the product 03 into a tubular bag 02. At time t2, the speed of rotation of the metering screw 05 is reset to zero.

[0040] In the lower part of FIG. 4, the pressure to which the vacuum chamber 20 is pressurized via the pressure line 16 is marked out. In the diagram, vacuums P are marked out upward and pressures P+ are marked out downward. As is visible, a vacuum from the vacuum source 12 is established in the vacuum chamber 20 via the pressure line 16 during every single work cycle at time t1 synchronously to the rotation of the metering screw 05 so as to suck gas from the product 03 waiting in the metering tube during the thus defined suctioning phases 29. The vacuum is maintained starting at time t1 until time t3 within the suctioning phases 29 during each work cycle. Time t3 occurs shortly after the switch-off time t2 of the metering screw in order to ensure, by corresponding compacting of the product even after the metering screw 05 has been switched off, that the product 03 does not drop out of the metering tube 06 into the fusion zone between the sealing jaws 08.

[0041] The version of the method illustrated in FIG. 4 intends for the pores in the filter mat 19 to be cleaned in every third work cycle during a blowing phase 28. Hence, at time t4 of each third work cycle, the switching valve 13 is switched and the vacuum chamber 20 is then subjected to pressure from the pressure source 11 via the pressure line 16. The pressure impulse ends at time t5 shortly prior to the start of the respective fourth work cycle. The pressure impulse briefly blows the pores in the filter mat 19 of the suction bushing 17 and blows the product particles stuck therein back into the direction of the metering screw 05. Since cleaning of the suction bushing 17 in the compactor 07 takes place during the tubular-bag production process, namely in each third work cycle, the cleaning work on the compactor 07 that would otherwise have to be performed regularly and which causes undesired downtimes can be significantly reduced or even avoided entirely.

[0042] FIG. 5 shows an alternative version of the method in a time diagram in which the speed of rotation of the metering screw 05 is marked out in the upper part and the pressure supply of the compactor 07 is marked out in the lower part. Contrary to the method illustrated in FIG. 4, cleaning of the suction bushing 17 takes place by way of blowing phases 28 during every single work cycle in the method illustrated in FIG. 5. The pressure supply is switched to pressure at time t6 during every single work cycle, whereby the pores in the filter mat 19 are blown. Then, at time t7 shortly prior to the end of the respective work cycle, the pressure supply is reset to zero.

[0043] In FIG. 6, the time diagram of another version of the method for cleaning the compactor 07 by blowing the pores in the filter mat 19 during the tubular-bag production process is schematically illustrated. The individual work cycles of the tubular-bag production process are again separated from each other by dashed vertical lines. As in the previously explained method according to FIG. 4 and FIG. 5, the vacuum chamber 20 is again subjected to the vacuum from the vacuum source 12 between times t1 and t3 during every single work cycle. In the first work cycle at the beginning of the tubular-bag production process, the effective vacuum in the vacuum chamber during application of the vacuum from the vacuum source 12 is measured using the pressure sensor 15. Said effective vacuum in the vacuum chamber 20 during the first work cycle is stored as an initial vacuum value 22. Since the pores of the suction bushing 17 are not yet blocked at the beginning of the tubular-bag production process, the initial vacuum value 22 is below the vacuum level from the vacuum source 12.

[0044] A limit value 23 which serves to trigger cleaning of the compactor 07 by blowing the pores in the suction bushing 17 is determined based on the measured initial vacuum value 22. The limit value 23 can be double the initial vacuum value 22, for example.

[0045] On the right side of FIG. 6, two work cycles of the tubular-bag production process at a later time, such as after running of several hundred work cycles, are marked out. As is visible, the vacuum value 24 measured using the pressure sensor 15 has largely approached the limit value 23 because of the growing blockage of the pores in the suction bushing 17. If the vacuum value 25 now exceeds the limit value 23 in the next work cycle, this will cause the controller 14 to automatically trigger a blowing phase 26 in which the vacuum chamber 20 is subjected to pressure from the pressure source 11 during times t8 and t9 so as to blow the pores of the suction bushing 17.

[0046] In FIG. 7, the process parameters of another version of the method for cleaning the compactor of FIG. 2 are presented in a time diagram. This version of the method largely corresponds to the version of the method illustrated in FIG. 6. However, this version of the method intends for the blowing phases 30 to seamlessly transition into each other starting from initial time t10 of the first work cycle. Again, the limit value 23 serving to trigger cleaning of the compactor 07 by blowing the pores in the suction bushing 17 is determined based on the measured initial vacuum value 22.

[0047] In the 40.sup.th work cycle, for example, the measured vacuum pressure 31 is just barely below the limit value 23. In the subsequent 41.sup.st work cycle, the measured vacuum value 32 is then just above the limit value 23, which causes the controller to trigger a cleaning cycle including a blowing phase 33 so as to clean the pores by blowing out deposited particles. After that, starting with the next work cycle, the vacuum chamber is permanently subjected to a vacuum again so as to compact the product by sucking out gas. Once the measured vacuum value exceeds the limit value 23 again, another cleaning cycle including a blowing phase 33 will be triggered.