METHOD AND APPARATUS FOR DEFOAMING A PASTEURIZED LIQUID PRODUCT

Abstract: A method for filling an open top container with a foamable pasteurized liquid such as milk or fruit juice breaks down foam that is generated within the container so that the foam does not interfere with the sealing of the container. The container (14) is advanced by a conveyor to each of a plurality of filling stations (12a-12d) where the liquid is dispensed at a high flow rate into the container (14) in predetermined incremental amounts. The container (14) is then advanced to a defoaming station (120) where a fine spray of the same foamable pasteurized liquid is directed into the container to break down the foam. After the foam is broken sufficiently so as not to interfere with the sealing of the container (14), the container (14) is advanced to top sealing stations.

Description: - 1 - METHOD AND APPARATUS FOR DEFOAMING A PASTEURIZED LIQUID PRODUCT BACKGROUND OF THE INVENTION 1. Field of the Invention. The present invention relates to a method and apparatus for filling an open top container with a foamable pasteurized liquid product. In particular, the present invention relates to a method and apparatus for reducing the foam produced by discharging a liquid product into an open top container, so that reliable sealing of the top of the container can be achieved. 2. Description of the Prior Art. Methods and equipment for filling and sealing gable top cardboard cartons with milk, fruit juice and other various liquid food products are well known. In filling the cartons, the erected cartons are typically transported along a conveyor line from station-to-station. There usually are at least two or more stations at which a predetermined amount of the liquid is dispensed at a high rate into the open top of the carton to fill the carton. In the case where there are two stations, typically half the liquid is dispensed at the first station, and the other half of the liquid is dispensed at the second station. After the carton has been filled at the second or final station, the carton is transported along the conveyor to another series of stations where the gable top is formed and sealed. The carton is typically polyethylene coated, so that the sealing of the gable top is done with a combination of heat and pressure. The equipment that fills the cartons operates at a high production rate, and therefore, - 2 - the liquid must be dispensed into the carton rapidly. When the liquid is rapidly discharged into the carton, a foam develops on and over the surface of the liquid. The amount of foam produced during filling depends upon the ' rate in which the fluid is dispensed from a dispensing nozzle and the particular configuration of the dispensing nozzle. Some configurations of nozzles have more problems than others with foam. However, all dispensing nozzles form some foam within the carton on the surface of the liquid. The foam becomes a problem when trying to seal a gable top carton or any carton using an adhesive that must be heated before adhesion occurs. The foam can prevent the adhesive from adhering and prevent the gable top from being properly sealed. It is necessary, therefore, to remove excess foam after filling the carton. In the past, a variety of methods have been developed in trying to eliminate the foam within the carton. One popular method in the past has been to use some form of vacuum device, which sucks the foam out of the carton. Unfortunately, the vacuum also tends to draw whatever dust, bacteria and other particles that are present in the air over the surface of the liquid food product into the carton. Contamination of the liquid food product as a result of the defoa ing process can be a significant problem. The Rydell U.S. Patents 2,792,029 and 2,796,894 show a tubular vacuum defoamer for milk filling machines. The Rydell '029 Patent further includes a beater having blades positioned in the vacuum stream. The beater causes the foam to be directed out on the side wall of the tube so that it O P is returned to a liquid form and back into the container. The Ward U.S. Patent 2,753,098 describes another vacuum milk defoaming device wherein the foam is removed by a vacuum defoa er which includes a plate that covers the top of the open container and a vacuum line extending through the plate to suck foam out of the container. Although the device of the Ward Patent uses a plate to cover the top of the container, in a high production type filling machine, openings between the plate and the top of the container still exist for dust, bacteria and other particles to be drawn near the surface of the liquid food product in the container. The Burger et al U.S. Patent 3,169,561 describes an elastic wave generator which directs elastic waves onto the surface of the liquid in the container to break up the foam. The Ulmen et al U.S. Patent 2,752,083 and Wollenwever U.S. Patent 2,328,372 use a gas that is directed onto the foam to break up the foam. The Ulmen et al Patent shows a defoaming arrangement in which a high pressure gas, such as air or steam, is directed in a jet onto the surface of the liquid in the carton to break up the foam. Gas nozzles are positioned between liquid discharge nozzles which fill the carton at successive stations. The Wollenwever Patent describes the use of a heated gas, specifically steam, which is blown onto the surface of the liquid to break up the foam. The Andre U.S. Patent 2,604,247 also uses steam which is discharged from a nozzle to assist in removing foam in cooperation with a suction pipe. The McKinnis U.S. Patent 2,377,796 includes a machine which fills containers with an oxidizable liquid, such as fruit and vegetable juices. Atmospheric air is purged from the container by a jet of inert gas or steam. When the juice is introduced into the container, it is surrounded by a protective blanket of inert gas or steam. None of the above-mentioned patents describe a method or device which provides a simple solution in reducing the problem of foam developing in a container so that the foam does not interfere with the sealing of the container. Contamination from the environment or introduction of a fluid into the container other than the liquid product being packaged occurs using many of the above methods. SUMMARY OF THE INVENTION The present invention includes a method and apparatus for breaking down the foam being formed in a container when a foam-producing pasteurized liquid food product is being discharged into the container at a high rate. After substantial reduction of the foam, the container can then be sealed without any interference from the foam during the sealing process. Using the method and apparatus of the present invention, containers are progressively moved along a plurality of discharge or filling stations with each discharge station discharging a predetermined amount of the liquid food product at a high rate through a nozzle mechanism. The containers are then moved to a defoaming station where a nozzle for producing a fine spray of the same pasteurized liquid food product directs the fine spray onto the foam in the container until a substantial part of the foam has broken down. This permits subsequent sealing of the container without interference from the foam. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a front view of a liquid product filling machine of the present invention. Figure 2 is a partial cross sectional view of the defoaming device of the present invention broken away from the filling machine with portions shown whole for purposes of clarity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A filling machine generally indicated at 10 is shown in Figure 1. The filling machine 10 is typically part of a larger apparatus which erects flat, collapsed tubular cartons to produce open top cartons, fills the cartons with liquid food product using the machine 10, and seals the tops of the filled cartons. An example of one such apparatus is described in an application entitled "Multiple Mandrel Carton Erecting, Filling and Sealing Machine with Two-Stage Loading," Serial No. 319,801 and "Carton Filling Apparatus," Serial No. 319,691, both applications being filed on November 9, 1981 and being assigned to the same assignee as the present application. The apparatus described in the above-mentioned applications is a variation from the structure shown in Figure 1 of the present application, but the present invention is equally applicable to all types of filling machines that generate foam when filling an open top container with a liquid food product. Briefly, the machine 10 includes a plurality of dispensers 12a, 12b, 12c, and 12d which define dispensing (or filling) stations and dispense a predetermined amount of a pasteurized liquid food product, such as milk, into open top containers 14. The dispeners 12a, 12b, 12c and 12d are supplied - 6 - milk, preferably through a common header pipe (not shown), which in turn is supplied milk from a bulk supply tank (not shown). Each dispenser 12a, 12b, 12c, and 12d is preferably connected to the header pipe (not shown) by supply pipes 16a, 16b, 16c, and 16d which have a 90° bend for connection to the header pipe. Each dispenser 12a, 12b, 12c and 12d discharges a predetermined incremental amount of milk to.each container 14 as each container 14 is positioned under that dispenser. The containers 14 are advanced along a conveyor line in the direction of arrows 18. For example, in filling each container 14, the container 14 is indexed by a conveyor (not shown) under first dispenser 12a, wherein a first predetermined amount of milk is discharged at a high rate into the container 14. Then the container 14 is indexed to the next dispenser 12b and a second predetermined incremental amount of milk is discharged at a high rate into the container 14. Similarly, a third predetermined incremental amount of milk is discharged from dispenser 12c into the container 14 and the last predetermined incremental amount of milk is dispensed by dispenser 12d. The incremental amounts of milk discharged by each dispenser add up to the total volume of milk required for the particular size of container 14 being used. The dispensing apparatus shown in Figure 1 is supported from a generally vertical main plate 20. Mounted near the top of main plate 20 is air cylinder 22, which provides the drive for dispensers 12a-12d. Air cylinder 22 has a vertically movable piston rod 24 which is coupled to drive bar assembly 26. Vertical guide shafts 28 and 30 are attached at - 7 - their lower ends to drive bar assembly 26 and are movable vertically in bearing support assemblies 32 and 34, respectively. In the embodiment shown in Figure 1, each dispenser 12a-12d includes a piston shaft 36, a piston rod pin 38, a cylinder 40, a piston 42, O-rings 44, a valve assembly 46, a nozzle 48, a rod seal 50, cleaning port 52 and top cover assembly 54. The upper ends of piston shafts 36 are connected to drive bar assembly 26 by piston rod pins 38, so that vertical movement of piston rod 24 of air cylinder 22 is transmitted through drive bar assembly 26 to cause vertical movement of piston shafts 36. In Figure 1, cylinder 40 has been broken away partially to show the internal construction of a portion of dispenser 12b, whicn is typical of the construction of all four dispensers 12a-12d. As shown in Figure 1, piston rod 36 extends downwardly through rod seal 50 and top cover assembly 54 into cylinder 40. At its lower end, piston shaft 36 has a T head 56 which mates with a corresponding T slot in the upper end of piston 42 to provide a connection between piston shaft 36 and piston 40. The upper ends of cylinders 40 are provided with cleaning ports 52, which are connected to cleaning pipe 58, so that the back (upper) side of the pistons 42 and the upper ends of the cylinders 40 can be cleaned. The stroke of air cylinder 22 is controlled by switch rod 60 and limit switch 62. Switch rod 60 is connected to drive bar assembly 26 by screw 64, while limit switch 62 is mounted to main plate 20 by switch plate 66. The lowermost position of drive bar assembly 26 is determined by the point at which OMPI switch rod 60 engages limit switch 62. In operation, air cylinder 22 is controlled to cause reciprocating upward and downward movement of piston shafts 36, and thus reciprocal upward and downward movement of pistons 42 within cylinders 40. As pistons 42 are simultaneously driven upward, the valve mechanisms 46 permit milk (or other pasteurized liquid) from supply pipes 16a-16d to be drawn into cylinders 40. When pistons 42 are simultaneously driven downward, the valve mechanisms 46 are reversed to allow the milk from cylinders 40 to be forced out of nozzles 48 into the containers 14 positioned below those nozzles. This description of the dispensing apparatus of machine 10 is provided in order to understand the manner in which cartons may be filled in a typical carton filling machine. The present invention, however, is not concerned with the specific construction of dispensers 12a-12d, but rather with an improved method and apparatus for elminating foam which has been created while the containers 14 were being filled. It should be recognized, therefore, that the present invention can be used with a wide variety of different types of dispening apparatus in a carton filling machine, and is not limited to the particular type of dispensing apparatus shown in Figure 1. The present invention is a defoamer 120 for breaking down the foam of the liquid product within the container 14. Since the dispensers 12a, 12b, 12c, and 12d of the machine 10 dispense liquid at a high rate, foam is created on and above the liquid surface of the milk. Frequently, the foam is of such an amount that it interferes with the sealing process - 9 - of the top of the container. The container 14 is typically a polyethylene coated cardboard carton which is sealed under heat and pressure. During filling, the foam rises sufficiently high to cause a problem in sealing the top of the container. The defoamer 120 of the present invention sufficiently reduces the amount of foam in each container 14 so that the container 14 is sealed without interference from foam. The defoamer 120 of the present invention reduces foam in each container 14 by directing a fine spray of the same pasteurized liquid into the container after the container 14 has been filled by dispensers 12a-12d. The fine spray droplets impinge on the foam bubbles and break down the foam. This is achieved without introducing any contamination or any other substance other than pasteurized liquid. Thus, defoaming is achieved while maintaining the integrity of the pasteurized liquid. The defoamer 120 is shown in detail in Figure 2, where the components are generally shown in section, with other components shown in whole for ease of visualization. The defoamer 120 is positioned at a defoamer station located along the conveyor line after the last dispensing station (dispenser 12d) and before the sealer stations (not shown) where the gable top of each container 14 is closed and sealed. The defoamer 120 preferably includes a central milk supply passage 122 which is connected between supply pipe 16d and dispenser 12d so that supply pipe 16d supplies both defoamer 120 and the dispenser 12d with milk. The passage 122 has a flange 124 for attachment to a flange 126 of the supply pipe 16d. A clamp 128 engages and abuts the flanges 124 and 126 to each other so that a fluid seal is created. The passage 122 also has a flange 129 at another end for attachment with a flange 130 of the inlet pipe 132 of the dispenser 12d. Similarly, a clamp 134 engages and secures the flanges 129 and 130 to each other so that a fluid seal is made between the flange 129 and the flange 130. Defoamer 120 includes a plunger 136 which is coaxially positioned within an upper housing 138 which has a plunger head 136a at its lower end, and intermediate neck section 136b, an upper end section 136c and a T slot 136d in upper end section 136c. In Figure 2, plunger 136 (which is not in section) is shown in its uppermost position. Plunger 136 is movable vertically downward from that uppermost position in the direction shown by arrow 140. The plunger 136 is moved up and down by an air cylinder 142. Piston rod 142a of air cylinder 142 is connected by T head upper connector 142b to T slot 136d in upper section 1.36c of plunger 136. The upper housing 138 has an upper flange 144 for sealing with a lower flange 146 of the air cylinder 142. A clamp 148 engages and secures the flanges 144 and 146 to each other. The plunger 136 slides along a bushing 150 which is coaxially positioned within the upper housing 138 and which circumferentially surrounds the plunger 140. An 0-ring 152 is located on a lower edge of the bushing 150 to provide a fluid seal between the lower portion of the bushing 150 and the upper housing 138. Plunger head 136a is coaxially aligned with a chamber 154 of a lower housing 156 of the defoamer 120. Plunger head 136a is movable from its uppermost position above chamber 154 (as shown in Figure 2) to a lowermost position within chamber 154. The chamber 154 communicates with the passage 122 and is filled with a predetermined amount of milk when plunger head 136a is in its uppermost, position. When plunger 136 is driven downward by air cylinder 142, plunger head 136a moves downward into chamber 154 and forces the predetermined amount of milk out through nozzle tip 158 at the bottom end of lower housing 156 and into the container 114 which is positioned at the defoamer station. The milk is forced out of nozzle tip 158 in the form of a fine spray, which breaks up foam in container 114. Nozzle tip 158 is positioned within a bore 160 in a lower portion of the housing 156. The nozzle tip 158 has a spray opening 159 designed to form a fine spray of milk. In preferred embodiments, the spray opening 159 has a diameter which is one-eighth inch or less. The particular diameter depends upon the properties of the liquid being sprayed, the volume of chamber 154, and rate at which plunger head 136a forces the liquid out of chamber 154. A spring 162 and a check ball 164 are positioned above nozzle tip 158 within the bore 160. The spring 162 is in a compressive state and holds the check ball 164 seated against an opening 166 to form a check valve. The opening 166 provides a fluid passage between the bore 160 and the chamber 154. A spring clip 168 retains the nozzle tip 158 within the bore 160 such that the upper end of the nozzle tip retains the spring 162 against an upper end of bore 160 and in a compressive state. As mentioned previously, container 14 is indexed from one dispenser station to the next with each dispenser 12a-12d delivering an incremental amount of the milk at a high rate. After the last dispenser station {dispenser 12d), the container 14 is indexed under the defoamer 120 of the present invention. The plunger 136, as shown in Figure 2, is initially in the up position, so that chamber 154 fills with milk from passage 122. When the container 14 is beneath the defoamer 120, the plunger 136 is pushed downwardly by the air cylinder 142 and plunger head 136a is forced into the chamber 154. The plunger head 136a pushes the predetermined amount of milk within the chamber 154 through the opening 166 and unseats the check ball 164. When the check ball 164 is unseated, the milk enters the bore 160 and is forced through the spray opening 159 to form a fine spray that is directed onto the foam in the container 14. The spray droplets of the fine spray impinge on and break down the foam. When the plunger head 136a has traveled to its lowermost position within the chamber 154 (as indicated by phantom lines) and the chamber 154 is empty of milk, the spring 162 forces the check ball 154 up against the opening 166. As the plunger head 136a is withdrawn from the chamber 154, the chamber 154 once again fills up with a predetermined amount of milk from passage 122 so that defoamer 120 is ready when the next container 14 is advanced to the defoamer station. The chamber 154 holds a sufficient amount of milk to break down the foam in the container 14. However, the amount of milk contained in chamber 154 is a minimal quantity in comparison to the volume of milk in the container 14, and therefore does not appreciably change the volume of the milk within the container 14 or affect the accuracy of the volume of OMPI milk within the container 14. In a preferred embodiment, the volume of chamber 154 is about 0.25 ounce, which is about one to three percent of a typical volume (20 ounces to 8 ounces) of liquid in container 14. This is quite important since the accuracy of the volume in the container must be maintained in very price competitive products such as milk or juices. Volumetric inaccuracy can be economically significant due to the large number of containers which typically are filled every day with this type of equipment. In addition, because the spray from the defoamer 120 of the present invention is the same pasteurized liquid product that is being dispensed into the container 14, there is no contamination of the container or dilution of the milk or juice, and no danger of negating the pasteurization procedures which were previously taken to pasteurize the liquid. Although the present invention has been -described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. O P

Claims: WHAT IS CLAIMED IS: 1. A method of filling an open top, sealable container with a foamable pasteurized liquid product, the method including: discharging a predetermined quantity of the foamable pasteurized liquid product into the container through the open top; and reducing any foam generated by discharging before sealing the open top of the container, by directing a fine spray of the same pasteurized liquid product into the container and onto the foam until a sufficient amount of the foam is broken down so that the foam will not interfere with subsequent sealing of the top of the container. 2. The method of claim 1 wherein discharging a predetermined quantity of the foamable pasteurized liquid product comprises: conveying the container intermittently along a conveyor path to a plurality of dispensing stations; and discharging a portion of the predetermined quantity into the container through the open top at each of the dispensing stations. 3. The method of claim 2 wherein reducing any foam generated comprises: conveying the container from a last dispensing station of the plurality of dispensing stations to a defoaming station; and discharging, at the defoaming station, the fine spray of the same pasteurized liquid product into the container through the open top to break down the foam within the container which was generated as a result of discharging at the dispensing stations. 4. The method of claim 1 wherein reducing any foam generated comprises: filling a chamber with a quantity of the pasteurized liquid, the chamber having a volume which is less then about three percent of a volume of the liquid product in the container; and. forcing the quantity of the pasteurized liquid out of the chamber and through a nozzle to form the fine spray. 5. An apparatus for filling an open top container with a foamable pasteurized liquid food product from a supply source, the apparatus comprising: means connected to the supply source for discharging a predetermined amount of the foamable pasteurized liquid food product into the container; and means connected to the supply source for directing a fine spray of the same foamable pasteurized liquid food product on the foam in the container to break down the foam so that the foam will not interfere with subsequent sealing of the open top of the container. 6. The apparatus of claim 5 wherein the means for discharging a predetermined amount of foamable pasteurized liquid food product comprises a dispenser positioned at each of a plurality of dispensing stations, each dispenser discharging an incremental amount of the pasteurized liquid food product through the open top into the container as the container is indexed from one dispensing station to another dispensing station. 7. The apparatus of claim 5 wherein the means for directing a fine spray includes: a supply conduit for supplying the pasteurized liquid food product connected to the supply source; a housing having a chamber communicating with the supply conduit and being a predetermined size sufficient to hold a predetermined quantity of pasteurized liquid food product sufficient to break down the foam while not adding significantly to a volume of the pasteurized liquid food product within the container; a spray nozzle for spraying the predetermined quantity of the pasteurized liquid food product in a fine spray positioned below the chamber in the housing; valve means positioned in a fluid passage between the chamber and the spray nozzle for controlling the flow of the pasteurized liquid food product therebetween; and plunger means for forcing the predetermined quantity of the pasteurized liquid food product from the chamber and cooperating with the valve means such that the pasteurized liquid food product is forced through the spray nozzle to produce the fine spray. 8. The apparatus of claim 7 wherein the valve means includes a spring in compression within a bore in the housing and a ball seatable against a passage communicating with the chamber, the ball seated against the passage, by compressive force of the spring. 9. In an apparatus of the type in which an open top, sealable container is conveyed along a conveyor path to at least one dispensing station where a pasteurized liquid food product is discharged into the container through the open top and subsequently is conveyed to at least one top sealing station at which the open top is sealed, the improvement comprising: defoamer means positioned at a defoaming station located along the conveyor path between the dispensing station and the top sealing station for directing a fine spray of the pasteurized liquid food product into the container through the open top to break down foam within the container which was generated at the dispensing station so that any remaining foam in the container will not interfere with sealing of the top of the container at the top sealing station. - ' w ' o ' 10. The apparatus of claim 9 wherein the defoamer means comprises: a supply conduit for supplying the pasteurized liquid food product connected to- the supply source; a housing; a chamber in the housing which communicates with the supply conduit for holding a predetermined quantity of pasteurized liquid food product sufficient to break down the foam while not adding significantly to a volume of the pasteurized liquid food product within the container; a spray nozzle for spraying the predetermined quantity of the liquid food product in a fine spray, the spray nozzle being positioned below the chamber in the housing; valve means positioned in a fluid passage between the chamber and the spray nozzle for controlling the flow of the pasteurized liquid food product therebetween; and plunger means for forcing the predetermined quantity of the liquid food product from the chamber and cooperating with the valve means such that the liquid food product is forced through the spray nozzle to produce the fine spray.

Inventors: BOUGIE STEPHEN L, CORNIEA DONALD G, SIEG WILLIAM F, BOUGIE, STEPHEN, L., CORNIEA, DONALD, G., SIEG, WILLIAM, F.
Applicants: LIQUIPAK INT INC, LIQUIPAK INTERNATIONAL, INC.
Application year: 1984
Main classification: B65B3
IPC codes: B65B3