Abstract:
A defoaming apparatus ( 22 ) defoams a foamable product that is dispersed into a container such as a TETRA REX gable-top carton ( 80 ). The defoaming apparatus ( 22 ) creates a sonic shock wave ( 110 ) that destroys most if not all of the bubbles of the foamable product. The defoaming apparatus ( 22 ) has a body ( 100 ) that defines a recessed cavity ( 102 ). A pair of electrodes ( 106, 108 ) is located within the recessed cavity ( 102 ). The opening to the cavity ( 102 ) can include a radio frequency filter ( 114 ) covering to absorb radio waves created from the sonic shock wave ( 110 ). The defoaming apparatus ( 22 ) is preferably disposed immediately after the filling of the container ( 80 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates to defoaming devices for foamable products. Specifically, the present invention relates to a defoaming device utilized on a packaging machine to decrease the foam level in a container prior to sealing of the container. 
     BACKGROUND OF THE INVENTION 
     In the packaging industry, productivity is synonymous with the ability to produce a greater number of cartons per hour than previous machines. In the field of form, fill and seal packaging machine, the ability to produce higher capacity machines is accomplished by analyzing, and as necessary, modifying each action performed on the machine. Through analyzing each action performed on the machine, the dwell time may be lessened while the indexed movement is increased in order to achieve higher capacity on the packaging machine. The dwell time is defined as the time period that each preformed container is stationary on the machine while an action is performed on the container. The indexed movement is defined as the time period that each pre-formed container is conveyed along the packaging machine from one station to the next. 
     For example, on a linear form, fill and seal packaging machine such as a TETRA REX® packaging machine available from Tetra Pak, Incorporated of Chicago, Ill., once a pre-formed container is filled with a product, conveyance of the container must be controlled to prevent sloshing of the product onto the sealing area of the container. However, it is desired to increase the conveyance speed of the product-filled container. To that end, the motion profiles of the conveyance of containers is controlled as set forth in U.S. Patent No. (co-pending U.S. patent application Ser. No. 08/848,888) entitled Servo-Controlled Conveyor System For Carrying Liquid Filled Containers, assigned to the assignee of the present invention. 
     Another possibility for increasing capacity would be to reduce the number of indexed dwell positions on the conveyor line. One possible dwell position that may be eliminated is the extra dwell position between the filling station and top sealing station. This station allows for the product foam in a recently filled container to settle prior to top sealing, which prevents wetting of the sealing area of the container with product foam. Other packaging machines such as rotary filling machines and vertical form, fill and seal machines have exhibited similar problems with foamable products. 
     One defoaming technique is set forth in U.S. Pat. No. 4,295,502, entitled “Method And Apparatus For The Elimination Of Foam Above The Level Of A Liquid, And Particularly Above A Packaged Liquid Such As Milk.” This technique discloses the use of ultrasonic waves to decrease the product foam in a container through disruption of the foam bubbles. The technique requires ultrasonic equipment positioned above the conveyor line. However, the ultrasonic device will increase the noise level on the packaging machine, and if other ultrasonic devices are employed on the machine, such as ultrasonic fitment applicators, then already high decibel levels may be doubled, coming close to intolerable decibel levels. Safeguards and other additions may be added to the machine to reduce noise, however, this further increases the cost of the packaging machine. Moreover, the use of ultrasonics for defoaming purposes has proven ineffective. 
     An alternative defoaming device is needed in the packaging industry to increase the packaging capacity of machines. Such a device desirably reduces foaming of the newly filled package, with minimal if any impact on the operating speeds of the overall packaging machine operation. Most desirably, such a device fits within the known physical parameters and sizing of known packaging machines. 
     SUMMARY OF THE INVENTION 
     The present invention provides an alternative to ultrasonic defoaming which effectively defoams a container filled with a foamable product. The present invention accomplishes this by providing a defoaming device that creates a shock wave to destroy or collapse the bubbles of a foamable product inside a container after filling. 
     One aspect of the invention is a defoaming device having a body with a reflective recessed cavity. Inside the cavity are two electrical terminals that, when a voltage is applied to one terminal, an arc is created between the terminals to complete the circuit. The discharge or arc superheats the air inside of the recessed cavity to create a shock wave. The shock wave is directed toward the container to destroy the bubbles of the foam. 
     Another aspect of the invention is a packaging machine having such a defoaming device positioned between a filling station and a top sealing station. Yet another aspect of the invention is a method for defoaming a carton filled with a foamable product. It is a primary object of the present invention to provide a method and apparatus to defoam pre-formed containers filled with a product on a packaging machine. 
    
    
     Other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the accompanying drawings, and the appended claims. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective view of a packaging machine; 
     FIG. 2 is an isolated view of the fill pipe, defoaming device, prefolder and top sealer of the packaging machine of FIG. 1; 
     FIG. 2 a  is an isolated view of the defoaming device of FIG. 2; 
     FIG. 3 is a partial cross-section side view of an open ended gable top carton; 
     FIG. 4 is a partial cross-sectional side view of a folded top gable top carton of the prior art; 
     FIG. 5 a  illustrates a gable top carton being filled with a foamable product; 
     FIG. 5 b  illustrates a filled gable top carton with foam; 
     FIG. 5 c  illustrates a filled gable top carton being defoamed at the defoaming device of the present invention; 
     FIG. 5 d  illustrates a defoamed gable top carton; 
     FIG. 6 is an isolated view of an alternate embodiment of the defoaming apparatus of the present invention over a plastic container such as a PET bottle which can be filled on a rotary filling machine; 
     FIG. 6 a  is a cross-sectional plan view of the apparatus of FIG. 6, more clearly illustrating the filter/screen of the apparatus; 
     FIG. 7 a schematic view of a TETRA TOP™ packaging machine having the defoaming device of the present invention integrated thereon; 
     FIG. 8 is a schematic diagram of a vertical form, fill and seal packaging machine; 
     FIG. 9 is a cross-sectional view of the machine FIG. 8 with the defoaming device of the present invention disposed about the fill pipe; 
     FIG. 10 is an electrical schematic diagram of a trigger circuit used in one embodiment of the present invention; and 
     FIG. 11 illustrates a sound guide that is used in one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described presently preferred embodiments with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     The present invention is directed toward a form, fill and seal packaging machine, for example a linear packaging machine for gable-top cartons such as a TETRA REX® machine available from Tetra Pak, Incorporated of Chicago, Ill. Those skilled in the art will, however, recognize that the present invention may be utilized with other machines to defoam a foamable product. Linear packaging machines may process one, two or any multiple of cartons simultaneously with each multiple of cartons being conveyed one indexed movement from station to station. The present invention allows for cartons filled with a foamable product to be defoamed prior to pre-folding and/or top sealing. 
     As shown in FIG. 1, a dual line packaging machine  20  for forming, filling and sealing cartons generally includes a defoaming device  22 , a top sealing station  24  and a filling station  26 , a sterilization station  28  which is composed of an ultraviolet radiation station  30  and a hydrogen peroxide station  32 , a bottom forming station  36 , a carton opener  37 , and a carton blank magazine  38 . From an operational perspective, the front  40  of the packaging machine  20  is where the processing begins, and the rear  42  is where the finished cartons are dispensed for distribution. 
     The packaging machine  20  may be divided along a horizontal plane defined by a table top  44 . The table top  44  divides the packaging machine  20  into an upper half  46  and a lower half  48 . A frame  50  defines the general structure of the packaging machine  20  and supports the table top  44  and the various stations. The lower half  48  of the machine  20  includes servomotors, drive cylinders, cam drives and other components. The upper half  46  includes the various stations, the product tank  56 , the filtered air system  58 , the conveyor system  60 , not shown in FIG. 1, and other components to process the cartons. 
     As shown in FIG. 2, the defoaming device  22  is positioned between the filling station  26  and a pre-folder station  62 . Such a filling station  26  is described in co-pending U.S. patent application Ser. No. 08/897,554, entitled “Dual Stream Filling Valve” and in copending U.S. patent application Ser. No. 08/816,056, entitled “Elliptical Cleaning Box For Filling Apparatus,” both of which are hereby incorporated by reference. 
     Further down line at the top sealing station  24  is an oven  64  for heating the panels for sealing, and the top sealer device  66  for sealing the top fin panels of a carton together to create a form, filled and sealed carton. The top fin panels form the sealing area as described below. Preferably the defoaming device  22  will cover two open top cartons being processed on a dual carton processing packaging machine  20 . For example, two cartons are filled simultaneously at two fill pipes  70   a-b , then conveyed to the defoaming device  22  in the next indexed movement to be defoamed, if necessary. Both cartons are conveyed under the defoaming device  22  for defoaming before the pre-folding station  62 . 
     Alternatively, although not shown, two smaller defoaming devices  22  can be used, with one device each being positioned over a carton for individually and independently defoaming the cartons before pre-folding at the pre-folder station. In still another alternative (also not shown) one carton is defoamed during the dwell while the other carton is defoamed during the indexed movement. Additionally, the packaging machine  20  may process only a single carton at each station, or it may process a multiple of cartons at each station. The defoaming device can be modified to accommodate any of the above alternatives, or any multiple of cartons processed in an indexed movement on the packaging machine  20 , without departing from the scope and spirit of the present invention. 
     The positioning of the defoaming device  22  over a dual processing line is best shown in FIG.  3 . Two cartons  80 a,b are positioned below the defoaming device  22 . The defoaming device  22  has a body  100  that defines a recessed cavity  102 . Preferably, the recessed cavity  102  has a parabolic shape into the body  100  thus forming a parabolic ceiling  104  of the recessed cavity  102 . This ceiling  104  is reflective to direct air towards the interior of each carton  80   a,b . Projecting from the body  100  are two electrical terminals  106  and  108 . For example, terminal  106  can be a cathode and terminal  108  can be an anode. For example, a high voltage current is sent through terminal  106  thereby establishing an electrical arc  109  between terminal  106  and terminal  108 . A sonic shock wave, illustrated by arrows  110 , is created by the electrical discharge. The shock wave  110  arises from the super-heating of the air within the recessed cavity  102  by the electrical discharge, similar to lightening. As the air heats, it expands thereby increasing the pressure within the recessed cavity  102 . The sonic shock wave  110 , or compressed air, is directed toward the interior of the cartons  80   a,b  to destroy the foam bubbles thereby defoaming the product in anticipation of pre-folding. The reflective ceiling  104  acts to reflect all vectors of the shock wave toward the interior of the cartons  80   a,b  to increase the defoaming effect of the shock wave  110 . However, those skilled in the art will recognize that the ceiling  104  may be of a non-parabolic shape and be within the scope and spirit of the present invention. 
     The body  100  may be encapsulated by a protective shield  112  composed of a metal or other protective material. Also, a protective screen  114  may be placed over the recessed cavity to prevent contact with the terminals  106  and  108 . The screen  114  may also be a radio frequency filter to absorb radio waves created with the sonic shock wave. The radio waves may have a deleterious effect on the operation of the packaging machine. A power supply  116  is connected to the terminals  106  or  108  to supply the high voltage current. One of the terminals  106  or  108  may also be connected to a ground  118 . 
     A carton  80  filled with a foamable product  201  filled therein is shown in FIG.  3 . The liquid level is approximately shown at line  199 . The foamable product  201  has bubbles  200  that approach the sealing areas  91  of the carton  80 . The same carton  80  is illustrated in FIG. 4 undergoing pre-folding without defoaming, as performed in the prior art. As shown in FIG. 4, the bubbles  200  of the foamable product  201  “wet” the sealing areas  91  of the carton  80 . Such wetting will interfere with proper sealing of the carton  80  and render the product filled carton  80  defective. For example, in a carton  80  having a cross section of 70 mm×70 mm, a ten millimeter thick layer of foam will require approximately forty-nine milliliters of volume. In a typical one liter carton, the volume between the level of the product and the top of the carton is approximately forty-nine milliliters. Thus, it is obvious that the foam will wet the sealing area if the carton is not defoamed, or allowed to settle prior to sealing. 
     FIGS. 5 a-d  illustrate the filling, defoaming and pre-folding of a single carton. In FIG. 5 a , a carton  80  is bottom-up filled with a foamable product  201  such as milk. A fill pipe  207  with a nozzle  209  attached thereon fills the carton as it is lowered on a lifter  211 . The liquid level  199  remains in proximity to the nozzle  209  during the entire filling process to reduce the amount of foaming. In FIG. 5 b , the carton  80  is now filled with a foamable product  201  and conveyed to the defoaming device  22 . The carton may contain any volume from one liter to one half gallon to one gallon. The cross-section of the carton may vary, for example from a 70 mm×70 mm cross section to a 47 mm×47 mm cross-section to a 70 mm×95 mm cross section. In FIG. 5 c , the defoaming device  22  is defoaming the carton. The terminals  106  and  108  create an electrical discharge, and the heated air in the form of one or more shock waves  10  is directed by the reflective ceiling  104  toward the bubbles  200  of the foam of the foamable product  201 . A single electrical discharge with an energy of 2×10 −5  joules has been found to be sufficient to collapse all of the foam bubbles in a carton having a cross-section of 70 mm×70 mm. The voltage delivered may be 15 kilovolts and the distance between the electrodes and the foam may be 1 to 2 centimeters. However, other parameters may be used in practicing the present invention. In FIG. 5 d , a carton with a defoamed product is ready for pre-folding. 
     An alternate embodiment of the defoaming apparatus  122  is illustrated in FIGS. 6 and 6 a . The alternative defoaming apparatus  122  is constructed as a semi-isolated component on a machine. In this embodiment, the defoaming apparatus  122  has a built-in step-up transformer  300  that receives standard voltage from a power supply along standard voltage line  301 , and transforms the electricity to a higher voltage for delivery to a high voltage power line  302  and to the electrode  106 . A ground  303  is connected to electrode  108  for delivering the after-effects of the arc/charge  109  to ground. 
     In a present embodiment, the electrical circuit  400  includes a trigger circuit  402 , as shown in FIG.  10 . The electrical circuit  400  includes a high voltage power supply  404 , a current limiting resistor  406 , a storage capacitor bank  408 , a discharge resistor  410 , a discharge relay  412  and the electrodes  106 ,  108 . The trigger circuit  402  enables the initiation of a spark upon receipt of a control signal. It has been observed that in a circuit without a trigger circuit, a spark will initiate when the potential (voltage) across the electrodes reaches a “value” sufficient to overcome the resistance of the air between the electrodes. As will be recognized by those skilled in the art, this “value” can be dependent upon a number of external or environmental factors, such as temperature, humidity, ion concentrations and the like. 
     To overcome the potential for inadvertent spark initiation, the trigger circuit  402  uses an ionization method in which a high voltage trigger pulse is applied to one side of an insulating plate  414 . This ionizes the gas (typically air) between the electrodes  106 ,  108  to initiate the discharge (spark). 
     In an effort to further reduce the opportunity for inadvertent spark initiation, it has been found that it is desirable to minimize or eliminate fouling the electrodes  106 ,  108 , which can occur by, for example, the accumulation of ionic material (salts, milk, juice, soap and the like) on the electrodes  106 ,  108 . As will be recognized by those skilled in the art, electrode  106 ,  108  fouling can affect the spark, and typically compromises spark generation by lowering the resistance path from the high voltage electrode  106  to ground. It has been found that fouling can be reduced or eliminated by spacing the defoaming device body  100  and electrodes  106 ,  108  from the product as it is filled into the carton  80 . In such an arrangement, a sound guide  500 , such as that illustrated in FIG. 11, can be positioned between the body  100  and the carton  80 . In this manner, any liquid that may project as the foam or bubbles collapse will not project so far as to contact, land on, or accumulate on the defoaming device  22  and in particular on the electrodes  106 ,  108 . In one embodiment, as illustrated in FIG. 11, the sound guide  500  has a body  502  that is configured as an elongated cylindrical tube. The tubular body  502  essentially envelopes the shock waves  110  that emante from the spark and directs the waves  110  onto the foamed product  201  in the carton  80 . 
     As shown in FIG. 6, the foamable product  201  is filled into a plastic container  333  having a rim  351 . The plastic container  333  maybe any type of plastic container such as a PET bottle, a high-density polyethylene bottle, or the like. The product may be any type of foamable product such as milk, cranberry juice, pineapple juice and grapefruit juice, as well as other foamable food products, and other foamable non-food products. The apparatus  22  may be integrated on various types of filling machines such as rotary fillers, linear fillers, vertical fillers and even in batch foamable product processing units. The defoaming apparatus  22  of the embodiment of FIG. 6 obviates the need for connecting high voltage power lines to the machine. Such high voltage power lines may interfere with the operation of the machine and can increase the potential for injury to machine operators. The defoaming apparatus  22  is connected to a standard power supply line, for example a 110 volt power line. This electricity is then transformed to a higher voltage by the transformer  300  within the apparatus  22 , thus providing a safer work environment and also limiting any interference that a high voltage line might have on a machine. 
     As shown in FIG. 7, an alternative packaging machine that may use the defoaming device of the present invention is generally designated  500 . The machine  500  creates a package with a fiberboard based body and an injection molded plastic top known as the TETRA TOP™ package that is available from the aforementioned Tetra Pak, Incorporated. In operation, a web of material  502  is formed into a carton sleeve at a forming station  504 . The sleeve is placed on a mandrel  506  and rotated to an injection molding station  508  where the plastic top is created. The partially formed package is placed on a conveyor  509 . The package is filled at a filling station  510  with a foamable product  201  that is received from a product tank  512 . The defoaming apparatus  22  is disposed adjacent the fill station  510 , similar to the arrangement on the gable-top carton packaging machine  20 . The bottom of the package is sealed at a bottom forming station  514  and the bottom flaps are sealed at a flap sealing station  516 . At a discharge point  518 , the package is released from the conveyor  509  for further distribution. The defoaming apparatus  22  will defoam the product filled package allowing for better bottom sealing of the package. 
     Yet another packaging machine that may utilize the apparatus  22  is a vertical form, fill and seal packaging machine. An example of such a machine is shown in FIGS. 8 and 9. The machine fabricates fiberboard packages such as the ubiquitous TETRA BRIK® package, or flexible plastic pouches such as a TETRA POUCH™ package. As shown in FIG. 8, the vertical packaging machine  600  receives a web of material  602 . The material  602  is formed around a fill tube  604 . The material is formed into a tube  607  by a longitudinal sealer  606 . The package is then cut-away from the tube  607  at a transversal sealer  608 . As shown in FIG. 9, the defoaming apparatus  22  can be mounted about the fill pipe  604  between the longitudinal sealer  606  and the transversal sealer  608 . The apparatus  22  can also contact the bubbles  200  and/or the foamable product  201 . 
     From the foregoing, it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the normal concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.