A METHOD FOR ADJUSTING AN INLET PRESSURE OF A PACKAGING MACHINE

Abstract

A method (400) for controlling a regulating valve (206) of a packaging machine (100), wherein the packaging machine (100) is a roll-fed packaging machine configured to receive a roll of a carton-based packaging material (102). The packaging machine (100) is configured to be connected to a processing line (202) via the regulating valve (206), wherein the processing line (202) is configured to feed a liquid food product (216) to the packaging machine (100) through the regulating valve (206). The method (400) comprises determining (S402) a product flow, using a flow meter (106), of the liquid food product in the packaging machine (100); determining (S404) an inlet pressure measurement (306), using a pressure sensor (204), of the liquid food product in the packaging machine (100); and making use of the inlet pressure measurement to the packaging machine (100) for adjusting the regulating valve (206), said regulating valve being configured to receive an output signal from a flow feed forward module (308) in combination with an output signal from a flow proportional-integral-derivative (PID) module (310), wherein the flow feed forward module (308) has the inlet pressure measurement (306) and a flow set point as input signals, and wherein the flow PID module (310) has the product flow and the flow set point as input signals.

Claims

1. A method for controlling a regulating valve of a packaging machine, wherein the packaging machine is a roll-fed packaging machine configured to receive a roll of a carton-based packaging material, wherein the packaging machine is configured to be connected to a processing line via the regulating valve, wherein the processing line is configured to feed a liquid food product to the packaging machine through the regulating valve, the method comprising: determining a product flow, using a flow meter, of the liquid food product in the packaging machine; determining an inlet pressure measurement, using a pressure sensor, of the liquid food product in the packaging machine; and adjusting the regulating valve, said regulating valve being configured to receive an output signal from a flow feed forward module in combination with an output signal from a flow proportional-integral-derivative (PID) module, wherein the flow feed forward module has the inlet pressure measurement and a flow set point as input signals, and wherein the flow PID module has the product flow and the flow set point as input signals.

2. The method according to claim 1, wherein the step of adjusting the regulating valve comprises regulating a flow of the liquid food product through the regulating valve.

3. The method of claim 1, wherein the flow PID module has a difference between the product flow and the flow set point as input.

4. The method according to claim 1, wherein the method further comprises determining a product level, using a level detector, of the liquid food product held in a vertical tube of the packaging material formed by the packaging machine, and calculating the flow set point as a function of the determined product level.

5. The method according to claim 1, comprising calculating the flow set point as a function of an output of a level PID module having the product level and a level set point as input signals, preferably having a difference between the product level and the level set point as input.

6. The method according to claim 1, wherein the flow set point is calculated as a function of one or more of a product level, a level set point, a machine speed percentage, a nominal flow percentage and/or a start flow percentage.

7. The method according to claim 1, wherein the pressure sensor comprises a metallic membrane.

8. The method according to claim 1, wherein the step of adjusting the regulating valve is based on real-time pressure measurements from the processing line.

9. A filling control system configured to adjust a regulating valve of a packaging machine, wherein the packaging machine is a roll-fed packaging machine configured to receive a roll of carton-based packaging material, wherein the packaging machine is configured to be connected to a processing line via the regulating valve, wherein the processing line is configured to feed a liquid food product to the packaging machine through the regulating valve, the filling control system comprising: a flow feed forward module configured to control the regulating valve, and having the inlet pressure measurement and a flow set point as input signals; and a flow proportional-integral-derivative (PID) module configured to control the regulating valve together with the flow feed forward module, and having the product flow and the flow set point as input signals, wherein the flow feed forward module is in parallel with the flow PID module.

10. The filling control system according to claim 9, wherein the filling control system further comprises a level PID module configured to feed into the flow feed forward module and the flow PID module and having the product level and a level set point as input signals.

11. The filling control system according to claim 9, wherein the filling control system is configured to receive real-time pressure measurements from the processing line.

12. A filling line configured to control product pressure and/or flow in the paper tube of a packaging machine, wherein the packaging machine is a roll-fed packaging machine configured to receive a roll of carton-based packaging material, wherein the packaging machine is configured to be connected to a processing line via a regulating valve, wherein the processing line is configured to feed a liquid food product to the packaging machine through the regulating valve, the filling line further comprising: a flow meter configured to determine a product flow of the liquid food product; a pressure sensor configured to determine an inlet pressure measurement of the liquid food product of the packaging machine; a flow feed forward module configured to control the regulating valve, and having the inlet pressure measurement and a flow set point as input signals; and a flow proportional-integral-derivative (PID) module configured to control the regulating valve together with the flow feed forward module, and having the product flow and the flow set point as input signals, wherein the flow feed forward module is parallel with the flow PID module.

13. The filling line according to claim 12, wherein the filling line further comprises a level detector configured to determine a product flow of the liquid food product of the packaging machine, wherein the level detector is located after the flow meter in the filling line direction.

14. The filling line according to claim 12, wherein the filling line further comprises a level PID module configured to feed into the flow feed forward module and the flow PID module and having the product level and a level set point as input signals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which

[0054] FIG. 1 is a general illustration of a roll-fed packaging machine.

[0055] FIG. 2 illustrates a roll-fed packaging machine connected to a processing line.

[0056] FIG. 3 illustrates a filling control system for a roll-fed packaging machine.

[0057] FIG. 4 is a flow chart illustrating a method for adjusting an inlet pressure of a packaging machine.

DETAILED DESCRIPTION

[0058] With reference to FIG. 1, a packaging machine 100, sometimes also referred to as a filling machine, is generally illustrated by way of example. The packaging machine 100 can be a roll-fed packaging machine used for packaging liquid food products in carton-based packages. Already in the 1940s this type of packaging machines was introduced by Tetra Pak, and it is today a well-known approach for packaging milk and other liquid food products in a safe and cost-efficient manner. The general approach can also be used for non-liquid food products, such as potato crisps.

[0059] Today, packaging material is often printed and prepared in packaging material production centers, also referred to as converting factories, and is shipped to a site where the packaging machine 100 is placed, e.g. a dairy. Usually the packaging material is loaded onto a reel before being transported. After arriving at the site, the reel is placed in the packaging machine as illustrated in FIG. 1.

[0060] During production a web 102 of packaging material can be fed from the reel through the packaging machine in a web feeding direction A. Before providing the liquid food product, a paper tube can be formed from the web 102 by forming a longitudinal sealing. The food product can be fed into the tube via a pipe 104 and a regulating valve 206 may be used for regulating a flow through the pipe 104. A lower end 108 of the tube can be fed into a folding device 110 in which a transversal sealing can be made, the tube can be folded according to folding lines, also referred to as weakening lines, and cut off such that packages 112 can be formed. Even though the folding device 110 is illustrated as one single device, the folding device 110 may comprise a number of different devices.

[0061] With reference to FIG. 2, a filling line 200 is generally illustrated by way of example. The filling line 200 can be configured to regulate pressure and flow in the paper tube of the packaging machine 100. The filling line 200 can comprise a filling control system 302 and a food handling system 304 configured to communicate with each other. The filling control system 302 will be discussed in more detail in connection with FIG. 3.

[0062] The food handling system 304 can comprise a processing line 202 and the packaging machine 100, wherein the processing line 202 can be connected to the packaging machine 100 via the regulating valve 206. The processing line 202 and the filling machine 100 can be connected such that the liquid food product may be fed therebetween through the regulating valve 206. The processing line 202 may be any processing line 202 known in the art.

[0063] The food handling system 304 can further comprise a pressure sensor 204 for determining an inlet pressure measurement of the liquid food product fed from the processing line 202 to the packaging machine 100. The inlet pressure measurement may be transmitted to the filling control system 302.

[0064] The packaging machine 100 can comprise a flow meter 106 for determining the product flow of the liquid food product fed from the processing line 202 to the packaging machine 100. The determined product flow may be transmitted to the filling control system 302. The packaging machine 100 can further comprise a level detector 208 for determining the product level of the liquid food product that may be fed from the processing line 202 to the packaging machine 100. The determined product level may be transmitted to the filling control system 302.

[0065] The inlet pressure measurement, the product flow and the product level may be referred to as filling parameters.

[0066] For a person skilled in the art, it is conceivable that the filling line 200 may comprise more than one pressure sensor 204, and/or more than one flow meter 106 and/or more than one level detector 208. It should also be noted that the packaging machine 100 may lack the flow meter 106 and/or the level detector 208.

[0067] The packaging machine 100 can further comprise a sterilization device 210, e.g. a hydrogen peroxide bath or an LVEB (Low-Voltage Electron Beam) station, for ensuring that the web 102 may be free from unwanted microorganisms. The packaging machine 100 can further comprise a longitudinal sealing station 212 for sealing the package along the longitudinal direction and a transversal sealing station 214, which may comprise two sealing jaws, for sealing the package transversally.

[0068] With reference to FIG. 3, a flow chart 300 of the filling control system 302 and part of the food handling system 304 of the filling line 200 is illustrated by way of example. It should be noted that not all features of the food handling system 304 are illustrated in FIG. 3. A purpose of the filling control system 302 is to provide for a more stable packaging machine 100 during pressure variations in the processing line 202.

[0069] As illustrated in FIG. 3, the food handling system 304 can comprise the regulating valve 206, the flow meter 106 and the level detector 208 as discussed in connection with FIG. 2. The food handling system 304 can be configured to transmit information to the filling control system 302. The filling control system 302 can be configured to adjust the inlet pressure of the packaging machine 100 based on the received information from the food handling system 304. The filling control system 302 can be configured to adjust the regulating valve 206 such that the inlet pressure of the packaging machine 100 can be adjusted. Thus, the food handling system 304 and the filling control system 302 can be configured to communicate with each other. By controlling the inlet pressure in the packaging machine 100 and/or the processing line 202, a quicker response for pressure disturbances occurring in the processing line 202 may be achieved.

[0070] The filling control system 302 may comprise a flow feed forward module 308 and a flow proportional-integral-derivative (PID) module 310. The filling control system 302 may further comprise a plurality of summing junctions 314a-e for summing one or more signals within the filling control system 302. The filling control system 302 may further comprise a plurality of switches 316a-c for controlling the signals that are traveling within the filling control system 302.

[0071] The flow feed forward module 308 can be configured to control the regulating valve 206. The flow PID module 310 can be configured to control the regulating valve 206. The flow feed forward module 308 may be arranged in parallel with the flow PID module 310 such that both the flow feed forward module 308 and the flow PID module 310 can be configured to control the regulating valve 206. Upon the flow feed forward module 308 and the flow PID module 310 can be controlling the regulating valve 206, the inlet pressure of the liquid food product may also be controlled. A purpose of the present arrangement, wherein the flow feed forward module 308 is arranged in parallel with the flow PID module 310, is to provide for a faster reactivity of the filling control system 302 to inlet pressure disturbances as well as real-time pressure information exchange between the packaging machine 100 and the processing line 202.

[0072] The filling control system 302 may further comprise a level PID module 312 for controlling the regulating valve 206. The level PID module 312 and the flow PID module 310 may together form a double PID feedback control loop in the filling control system, wherein the output signal from the level PID module 312 may be input signals to the flow feed forward module 308 and the flow PID module 310. Thus, the flow feed forward module 308 may be arranged in parallel with the double PID feedback control loop. By introducing the level PID module 312 in the arrangement may provide for another parameter that may be tuned and hence, controlled in the filling control system 302 in order to provide for the faster reactivity of the filling control system 302 to inlet pressure disturbances as well as the real-time pressure information exchange between the packaging machine 100 and the processing line 202.

[0073] As illustrated in FIG. 3, the liquid food product may be fed in the food handling system 304, wherein the food handling system 304 may be configured to transmit a product flow from the flow meter 106 and/or a product level from the level detector 312 to the filling control system 302. The food handling system 304 may further be configured to transmit an inlet pressure measurement 306 from the pressure sensor 204 (not illustrated in FIG. 3).

[0074] The inlet pressure measurement 306 may be transmitted from the pressure sensor 204 to the flow feed forward module 308, thus the inlet pressure measurement 306 may be an input signal to the flow feed forward module 308. A further input signal to the flow feed forward module 308 may be a flow set point, wherein the flow set point can be based on a machine speed percentage. The machine speed percentage may pass a second summing junction 314b and a third summing junction 314c before entering the flow feed forward module 308. According to one example, the flow set point may further be based on a start flow percentage and/or a nominal flow percentage. If the flow set point may be further based on the start flow percentage, a first switch 316a may be set such that the start flow percentage may be transmitted to the second summing junction 314b. Alternatively, or in combination, if the flow set point may be further based on the nominal flow percentage, a second switch 316b may be set such that the nominal flow percentage may be transmitted to the second summing junction 314b. The second summing junction 314b may be configured to combine the machine speed percentage with the start flow percentage and/or the nominal flow percentage. For a person skilled in the art, it is conceivable that the first switch 316a and the second switch 316b may be set such that both the start flow percentage and the nominal flow percentage are combined with the machine speed percentage in the second summing junction 314b.

[0075] The product flow may be transmitted from the flow meter 106 to a fourth summing junction 314d, wherein the product flow may be combined with the flow set point. The flow set point may be configured in the same way as discussed above. Thus, the flow set point may be the same flow set point arranged as the input signal to the flow feed forward module 308. The product flow in combination with the flow set point may be transmitted to the flow PID module 310, thus the product flow and the flow set point may be input signals to the flow PID module 310.

[0076] As discussed above, the flow feed forward module 308 may be arranged in parallel with the flow PID module 310. The output signal from the flow feed forward module 308 and from the flow PID module 310 may be combined in a fifth summing junction 314e. The output signal from the fifth summing junction 314e may be a control signal configured to control the regulating valve 206.

[0077] Thus, the regulating valve 206, may be controlled based on the inlet pressure measurement 306, the product flow and the flow set point.

[0078] An advantage with the present disclosure is that the pressure of the liquid food product in the paper tube may be known and controlled, compared to conventional packaging machines whose control systems have an inlet pressure normally set to a fixed value and hence, independent of other filling parameters in the system.

[0079] An advantage by controlling the regulating valve 206 based on determined values from both the flow meter and the pressure sensor is that a faster reaction of the regulating valve 206 is achieved. Thus, the regulating valve 206 may be controlled with higher feedback compared to conventional packaging machines and control systems due to the arrangement between the flow feed forward module 308 and the flow PID module 310. Thus, the flow feed forward module 308 may be configured to tune the filling parameter in a quicker way compared to conventional packaging machines and control systems.

[0080] According to one example, the product level may be transmitted from the level detector 208 to a first summing junction 314a, wherein the product level may be combined with a product set point. The product level in combination with the level set point may be transmitted to the level PID module 312, thus the product level and the level set point may be input signals to the level PID module 312. Upon a third switch 316c may be set, the output signal from the level PID module 312 may be transmitted to a third summing junction 314c. In the third summing junction 314c, the output signal from the level PID module 312 may be combined with the machine speed percentage and the start flow percentage and/or the nominal flow percentage. The output signal from the third summing junction 314c may be the flow set point. Thus, the flow set point may further be based on the output signal from the level PID module 312. In addition, the output signal from the third summing junction 314c may be transmitted to the fourth summing junction 314d and hence, combined with the product flow.

[0081] As discussed above, the flow feed forward module 308 may be arranged in parallel with the double PID feedback control loop. The output signal from the flow feed forward module 308 and from the double PID feedback control loop may be combined in a fifth summing junction 314e. The output signal from the fifth summing junction 314e may be the control signal configured to control the regulating valve 206.

[0082] An advantage by having the level PID module 312 in the filling control system is that the adjustment of the regulating valve 206 may be even more precise due to more filling parameters.

[0083] A further advantage by introducing the level PID module 312 in the arrangement is that, in combination with the switches 316a-c, it is possible to optimize the signals in the system and hence, adjust the regulating valve 206 in a more precise and efficient way.

[0084] Yet a further advantage, the filling parameters are used to tune the system for stability achievements through different phases in various configurations.

[0085] In FIG. 4 it is presented a flow chart illustrating a method 400 for adjusting the regulating valve by means of an inlet pressure measurement of a packaging machine 100, wherein the packaging machine 100 may be a roll-fed packaging machine configured to receive a roll of a carton-based packaging material 102. The packaging machine 100 can be configured to be connected to a processing line 202 via a regulating valve 206, wherein the processing line 202 can be configured to feed a liquid food product 216 to the packaging machine 100 through the regulating valve 206.

[0086] In a first step S402, a product flow of the liquid food product in the packaging machine 100 can be determined by using a flow meter 106. In a second step S404, an inlet pressure measurement 306 of the liquid food product in the packaging machine 100 can be determined by using a pressure sensor 204. Preferably, the pressure sensor 204 comprises a metallic membrane. In a third step S406, the regulating valve 206 can be adjusted by using a flow feed forward module 308 in parallel with a flow proportional-integral-derivative (PID) module 310. The flow feed forward module 308 has the inlet pressure measurement 306 and a flow set point as input signals. The flow PID module 310 has the product flow and the flow set point as input signals.

[0087] Optionally, the method 400 may further comprise the fourth step S408 of determining a product level, using a level detector 208, of the liquid food product 216 held in a vertical tube 308 of the packaging material 102 formed by the packaging machine 100. Upon that may be the case, the third step S406 may further comprise using the product level for adjusting the regulating valve 206.

[0088] Optionally, the third step S406 of adjusting the regulating valve may be further controlled using a level PID module 312 configured to determine the flow set point, wherein the level PID module has the product level and a level set point as input signals.

[0089] Optionally, the flow PID module 310 may further have the product flow and/or a machine speed percentage as input signal.

[0090] Optionally, the third step S406 of adjusting the regulating valve 206 may further be based on real-time pressure measurements from the processing line 202.

[0091] Below follows an alternative way of describing a method for controlling the regulating valve:

[0092] A method 400 for controlling a regulating valve 206 of a packaging machine 100, wherein the packaging machine 100 is a roll-fed packaging machine configured to receive a roll of a carton-based packaging material 102. The packaging machine 100 is configured to be connected to a processing line 202 via the regulating valve 206, wherein the processing line 202 is configured to feed a liquid food product 216 to the packaging machine 100 through the regulating valve 206. The method 400 comprises determining S402 a product flow, using a flow meter 106, of the liquid food product in the packaging machine 100; determining S404 an inlet pressure-measurement 306, using a pressure sensor 204, of the liquid food product in the packaging machine 100; and making use of the inlet pressure measurement to the packaging machine 100 for adjusting the regulating valve 206, said regulating valve being configured to receive an output signal from a flow feed forward module 308 in combination with an output signal from a flow proportional-integral-derivative (PID) module 310, wherein the flow feed forward module (308) has the inlet pressure measurement 306 and a flow set point as input signals, and wherein the flow PID module 310 has the product flow and the flow set point as input signals.

[0093] The features and advantages described in the context of the first aspect in the summary are also applicable for the method described above.

[0094] From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.

[0095] As already discussed, one or more embodiments may relate to the filling line 200 comprising the filling control system 302 and the food handling system 304. The food handling system 304 may comprise the processing line 202 and the filling machine 100. The food handling system 304 may comprise the regulating valve 206. The regulating valve 206 may connect the processing line 202 and the filling machine 100. The filling line 200 may be configured to perform the method according to one or more embodiments as described above.

[0096] The filling line 200 may be configured to control product pressure and/or flow in the paper tube of the packaging machine 100, e.g. a roll-fed packaging machine configured to receive a roll of carton-based packaging material 102. The packaging machine 100 is configured to be connected to the processing line 202 via the regulating valve 206, wherein the processing line 202 is configured to feed a liquid food product 216 to the packaging machine 100 through the regulating valve 206.

[0097] The food handling system 304 may comprise the pressure sensor 204 for determining the inlet pressure measurement of the liquid food product fed from the processing line 202 to the packaging machine 100. The inlet pressure measurement may be transmitted to the filling control system 302. The pressure sensor 204 may be positioned upstream of the regulating valve 206 in a direction of flow of the liquid food product 216.

[0098] Preferably, the food handling system 304 may comprise the flow meter 106 for determining the product flow of the liquid food product fed from the processing line 202 to the packaging machine 100. The determined product flow may be transmitted to the filling control system 302. The flow meter 106 may be positioned upstream of the regulating valve 206 in the direction of flow of the liquid food product 216.

[0099] Preferably, the food handling system 304 can comprise the level detector 208 for determining the product level of the liquid food product that may be fed from the processing line 202 to the packaging machine 100. The determined product level may be transmitted to the filling control system 302. The level detector 208 may be positioned downstream of the regulating valve 206 in the direction of flow of the liquid food product 216.

[0100] The filling control system 302 may comprise the flow feed forward module 308, the flow proportional-integral-derivative (PID) module 310 and/or the level PID module 312.

[0101] The flow feed forward module 308 may receive as input the inlet pressure measurement 306 from the pressure sensor 204 and the flow set point. The flow feed forward module 308 may comprise as an output a control signal for adjusting the regulating valve 206 calculated as a function of the flow set point and inlet pressure measurement 306.

[0102] The flow proportional-integral-derivative (PID) module 310 may receive as input the flow set point and the product flow. An output of the flow PID module 310 may be indicative of a difference between a real flow, measured e.g. by means of the flow meter 106, and a desired flow, i.e. the flow set point.

[0103] The level PID module 312 may comprise as inputs the level set point and the product level. An output of the level PID module 312 may be indicative of a difference between a real product level, measured e.g. by means of the level detector 308, and a desired level, i.e. the level set point.

[0104] The outputs of the flow proportional-integral-derivative (PID) module 310 and the flow feed forward module 308 may be combined. The regulating valve 206 may be adjusted as a function of the combined outputs.

[0105] The flow set point may be indicative of a target flow of product through the regulating valve 206. The flow set point may be calculated as a function of one or more of a start flow percentage a nominal flow percentage, a machine speed percentage, a level set point and/or a product level.

[0106] The step of adjusting the regulating valve 206 may comprise adjusting a flow of liquid product passing therethrough. The step of adjusting the regulating valve 206 may comprise physically opening or closing the valve 206 to regulate the flow of liquid product therethrough. That is, by means of filling control system 302 and the regulating valve 206 it is possible to control a flow of the liquid product through the filling machine 100. Advantageously, this way it is possible to control a pressure and/or flow of the liquid product.