FLOW WRAPPER WITH LEAKAGE-CONTROL OF THE RESULTING PACKAGES

Abstract

The present invention relates to a flow wrapper which comprises a form and/or film tube, which forms the planar film into a film tube and/or fills the film tube with a packaging item and which comprises means to provide a longitudinal- and/or cross-seal to the film tube.

Claims

1. A flow wrapper comprising: a form- and/or a film tube, which forms a planar film into a film tube and/or fills the film tube with a packaging item, and means to provide a longitudinal seal and/or a cross-seal to the film tube, and means to detect leaks at the seal.

2. The flow wrapper according to claim 1, wherein the flow wrapper comprises means to change an internal pressure the package item after its production.

3. The flow wrapper according to claim 1, wherein in the film tube and/or in the form- and/or fill-tube, a modified atmosphere or negative pressure is provided, wherein the flow wrapper comprises a sensor, which analyzes at least one component of a gas phase in the film tube and/or in the form- and/or fill-tube, and which is located in a vicinity of a downstream end of the form- and/or fill tube and/or upstream from a cross sealing means and/or in a vicinity of an outlet of the gas that modifies the atmosphere.

4. The flow wrapper according to claim 1, wherein the flow wrapper comprises means to apply a sensor spot to the film.

5. The flow wrapper according to claim 1, wherein the flow wrapper comprises at least one detector, which analyses at least one component of a gas atmosphere in the closed package.

6. A method to produce a package from a planar film, which has been formed into a film tube to which a longitudinal seal and at least one cross seal has been applied so that the package is hermetically closed, wherein at least one component of the atmosphere in the package is analyzed.

7. The method according to claim 6, wherein pressure inside the package is changed after its production.

8. The method according to claim 6 wherein at least one component of the gas phase is analyzed during or after a pressure change.

9. The method according to claim 6, wherein the film is provided around a form- and/or fill-tube, and a gas is introduced into the form- and/or fill tube, wherein at least one component of the gas is analyzed in a vicinity of a downstream end of the form- and/or fill tube and/or upstream from the cross sealing means and/or in a vicinity of an outlet of gas that modifies the atmosphere and/or in the film tube prior to application of a cross seal.

10. A flow wrapper comprising: a form- and/or a film tube, which forms a planar film into a film tube and/or fills the film tube with a packaging item, means to provide a longitudinal seal and/or a cross-seal to the film tube, means to detect leaks at the seal, means to change an internal pressure the package item after its production, means to apply a sensor spot to the film, at least one detector, which analyses at least one component of a gas atmosphere in the closed package, wherein a modified atmosphere or negative pressure is provided in the film tube and/or in the form- and/or fill-tube, wherein the flow wrapper comprises a sensor, which analyzes at least one component of a gas phase in the film tube and/or in the form- and/or fill-tube, and which is located in a vicinity of a downstream end of the form- and/or fill tube and/or upstream from a cross sealing means and/or in a vicinity of an outlet of the gas that modifies the atmosphere.

Description

[0036] The invention is now explained according to FIGS. 1-4a. These explanations do not limit the scope of protection. The explanations apply to all embodiments of the present invention likewise.

[0037] FIG. 1 shows an embodiment of a sensor located downstream from the form- and/or fill-tube.

[0038] FIG. 2 shows an embodiment with two sensors.

[0039] FIG. 3 shows the sealing tool.

[0040] FIG. 1 shows a first embodiment of the inventive flow wrapper 1, in the present case a so called vertical flow wrapper. This flow wrapper comprises a form- and/or fill-tube 5 with a form shoulder 6. A continuous or intermittently transported, initially planar film 4 is formed by the form shoulder into a film tube 19 which extends around the form- and/or fill-tube. The two opposing ends of the film 4 are sealed together by longitudinal sealing means 18. Downstream, relative to the transportation direction of the film tube 19, cross seal means 7 are arranged which provide a cross seal 20 to the film tube 19. The fill tube 5 is utilized to insert the items to be packaged into the film tube. In the present case this filling is carried out under a modified atmosphere by providing for example N.sub.2 and/or CO.sub.2 into the form- and/or fill tube and/or into the film tube here via a gas-lance 2 which is connected to a gas source. The gas flows out of the downstream end of the lance 2 and into the film tube. After the film tube is filled with the packaging item and the gas atmosphere is sufficiently modified, a cross seal 20 is supplied at the upstream end of the package to close it hermetically and the so finalized package 8 is cut off from the film tube 19. In the film tube 19, downstream from the form- and/or fill-tube 5, but upstream from the cross seal means 7, here essentially at the same vertical extension as the outlet of the gas-lance, a sensor/detector 9 is provided which analyzes the concentration of at least one component of the gas phase in the film tube. A sensor spot is for example illuminated by a light source, for example a LED and based on the concentration of the respective substance, the light emitted by the sensor spot changes. The sensor/detector 9 provides a signal via line 10 to the control of the flow wrapper, which hence knows the concentration of at least one component in the film tube. The signal can be used to control the amount of gas supplied by the gas source 3. The signal can also be used to control the transportation of the film tube 19 and/or the cross seal means 7 and/or the supply of the packaging item. Only in case the gas concentration is correct, the production of packages will be carried out, i.e. the film will be transported and/or the film tube will be filled with the packaging item and/or a cross seal will be applied.

[0041] FIG. 2 shows a modification of the embodiment according to FIG. 1, so that reference can be made to the disclosure regarding FIG. 1. In the present case, the inventive flow wrapper comprises additionally a second sensor 12 which is located upstream from the first sensor/detector 9 relative to the direction of flow of the film material 4 and/or the direction of the movement of the packaging item which drops through the fill-tube 5 from the top to the bottom by gravity. Preferably the second sensor is located inside the form- and/or fill-tube. The second sensor can be identically built as the sensor/detector 9 and is preferably also connected to the control of the flow wrapper and can be utilized to control the flow wrapper. If even the sensor/detector 12 reads the desired concentration of the gas component, it is even more assured that the gas concentration in the package is correct. By positioning the sensor/detector 12 in an appropriate position in the appropriate position, it can be assured that the form- and/or fill-tube is always filled sufficiently with modified gas, for example by controlling the gas supply with the signal of sensor/detector 12.

[0042] Reference is now made to FIG. 3. The flow wrapper is essentially described according to FIG. 1. The sensor 9 is not depicted but can be present. In this embodiment, the flow wrapper comprises an application device 14, here a printer, which applies a sensor spot 15 to the film, preferably the planar film, such that inside every package 18 a sensor spot is provided. The sensor spot is sensitive to the concentration of at least one component of the gas phase in the package. The inventive flow wrapper may comprise one or more detectors 16, which each read out a signal, for example a colour change, of the sensor spot, when the packages passes by, preferably while the package is moving. With the detector 16.1 it can be determined whether the atmosphere in the package is correct prior to closing or to sort it out in case the concentration is not correct. The sensor 16.2 is located inside or in the vicinity of a pressure chamber 17, which changes the pressure inside the package in case one of the seals 20, 21 is not perfectly gas tight. In the pressure chamber the pressure around the package can be increased or decreased and/or the pressure inside the package can be increased or decreased. In case of a modified atmosphere inside the package, air can be pressed inside the package, which changes the concentration of the gas component to be surveyed. This is realized by sensor 16.2 which measures the change in the signal, for example the electromagnetic waves emitted by the sensor spot 15 and knows that the seals 20, 21 are not perfect. The change in the signal from the sensor spot can also be recognized by comparing the readings of sensors 16.1 and 16.3. In case they differ, the concentration in the gas atmosphere has changed over time and/or due to the pressure chamber and it can be concluded that the respective package is not tight.

List of Reference Signs

[0043] 1 packaging machine, flow wrapper [0044] 2 gas supply, gas-lance [0045] 3 gas source [0046] 4 film [0047] 5 form- and/or fill-tube [0048] 6 form-shoulder [0049] 7 cross seal, cutting means [0050] 8 package [0051] 9 first sensor [0052] 10 first connection of the first sensor with the control of the machine [0053] 11 modified atmosphere in the film tube 19 and/or in the package 8 [0054] 12 second sensor [0055] 13 second connection of the first sensor with the control of the machine [0056] 14 application device for sensor spot, printer [0057] 15 sensor spot [0058] 16 detector [0059] 17 pressure means [0060] 18 longitudinal sealing means [0061] 19 film tube [0062] 20 cross-seal [0063] 21 longitudinal seal [0064] 22 outlet of the gas that modifies the atmosphere