Method of lap sealing a molten cheese product with non-wax film

A method of sealing a non-wax-coated film pouch contained within an enclosure includes forming an enclosure, positioning a piece of non-wax-coated film within the enclosure to form a floor and side walls of a pouch within the enclosure, dispensing a flowable dairy-based product into the pouch, overlapping portions of the film onto one another to produce a top wall over the dairy-based product, and heat sealing the overlapping portions of the top wall to each other.

BACKGROUND OF THE INVENTION

Many processed cheese and cream cheese manufacturers utilize pouch forming, filling, and sealing equipment from American Can Company or Hart Manufacturing. Conventional processes utilize wax coated film (usually cellophane based) to make various size pouches on horizontal pouch forming equipment. Once these pouches are formed, they are filled with a food product such as cheese and sealed utilizing a “lap seal.” A lap seal is made by over-lapping films. The wax sealant layer of the waxed film provides a way to form a lap seal on the package due to the low melt initiation temperatures of wax coupled with its excellent flow and caulking properties. The heat of the molten cheese product (typically about 165° F.) is generally sufficient to activate a wax lap seal. However, waxed films are expensive and have a tendency to delaminate, wherein the wax layer pulls away from the film substrate and sticks to the food surface upon opening.

Currently, most pouch forming equipment, when using non-wax film such as a polymeric film, requires the formation of a “fin seal.” A fin seal has edges of superimposed films bonded to each other, resulting in a pouch having a fin-like protuberance. A fin seal requires a wider film width to make the fin, thus requiring more material per pouch and also tending to require considerably slower line speeds to properly facilitate the sealing of the fin seal. Moreover, a high cost is associated with retrofitting equipment to provide for formation of a fin seal.

SUMMARY OF THE INVENTION

A method of sealing a non-wax-coated film pouch contained within an enclosure includes forming an enclosure, positioning a piece of non-wax-coated film within the enclosure to form a floor and side walls of a pouch within the enclosure, dispensing a flowable dairy-based product into the pouch, overlapping portions of the film onto one another to produce a top wall over the dairy-based product, and heat sealing the overlapping portions of the top wall to each other.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The ability to use a non-wax film without a fin seal results in considerable materials savings due to less film being required per package. Further, no costly retrofitting of equipment is needed for fin sealing capabilities. Moreover, increased production results from faster line speeds. In one example, this disclosure discusses the use of a non-wax-coated film in 5 lb. and 2 lb. processed cheese packaging operations. A finished block of wrapped cheese is sometimes referred to as a “loaf.”

This disclosure relates to the utilization of a lap sealable polymer packaging film with no wax component. In an exemplary embodiment, the film is used on horizontal pouch forming, filling and sealing equipment that packages processed cheeses and other variable viscosity foods and ingredients. Particularly suitable equipment is available from American Can Company and Hart Manufacturing.

An exemplary film is a 3 mil thick, 3-layer film available from Alcan Packaging. The first layer is composed of oriented polypropylene (OPP). A thin layer of polyurethane adhesive laminates the OPP layer to a sealant layer having glycerol monostearate (GMS) blended into an ethylene vinyl acetate—polybutylene (EVA-PB) and polyethylene sealant for enhanced cheese release properties. This film exhibits even better release properties if it has been allowed to cure for several weeks after manufacture and before use. In exemplary embodiments, the film did not exhibit tacking issues in the pouch gusset area. This sealant resin blend possesses a relatively low heat activation temperature (successfully sealing at about 220° F.). This film possesses adequate stiffness, a pouch formed therefrom flares properly in a carton, the pouch stays in the carton as an insertion ram exits, and the pouch travels to the filling area satisfactorily. An exemplary embodiment has a 14.875″ printed eyespot fiducial repeat pattern.

In an exemplary embodiment, a pouch former forms a pouch from film roll stock material. In one embodiment, the roll stock has a maximum diameter of 24 inches with a core diameter of 6 inches. Film is unwound from master rolls by means of a nip roll. The speed of the unwind is controlled by a programmable variable speed DC drive. An additional nip roll is located near the film cutoff. Constant tension between the nip rolls is maintained throughout the pouch former. Optional items in the unwind area include a splice plate for easy splicing of new roll material (a vacuum holds the web in place while splicing) and an auto tracker to maintain the edge position of the film. A powered unwind unit pulls the film web from the rolls. In an exemplary embodiment, an edge of the film is turned over to provide an “easy opening” feature. The turned over edge also adds rigidity to the pouch, which enables the pouch to be more erect in the carton. In an exemplary embodiment, each stock film roll core shaft has a roll side adjustment that is used to move the film roll to achieve top edge evenness.

A servo pneumatic web aligner guides the film through a set of stationary and dancer rollers into the forming board. The film runs through a former to make a c-fold and then a bottom gusset is opened to form a pouch of the desired size. In an exemplary embodiment, a pouch has a length of about 14 to 15 inches.

Pneumatically operated side seal bars section off the film web into individual pouches. Servo driven nip rolls pull the pouches into the opener/inserter section. As a pouch is fed out over the opener/inserter, it is held by a set of vacuum jaws. The pouch is then cut by a pneumatic shear knife and opened by servo driven vacuum boxes.

The folded film moves into a pneumatic heat sealing station, where end seals are placed onto the pouch. In an exemplary embodiment, the sealing assembly is activated through the use of servo driven seal jaws that offer variability in jaw dwell time. In an exemplary embodiment, compression washers are used on both sides of the sealing jaws to equalize sealing pressure on both sides of the jaw face. There are regions of greater pressure at the bottoms of the jaw faces. In an exemplary embodiment, the seal jaw back plate is made of silicone rubber.

Some embodiments use current “pancake style” metal sealing jaws. The heating bars are held by a pancake assembly that allows seal adjustment up and down as well as adjustments in pouch length. Shimming the sealing jaws on the “machine” side improves the sealing pressures obtained on the end seals. In an exemplary embodiment, the jaws were shimmed a total of 0.035 inch. The jaws thus shimmed had more consistent and even sealing pressure and allowed for the use of lower sealing temperatures. In other embodiments, older “scissors” type sealing jaws are used. The spring loaded pressures exhibited by the scissors jaws help provide for uniform sealing pressure on the end seals.

In an exemplary embodiment, the sealing jaw assembly has 4 heating zones that can be individually controlled for temperature and pressure: the top and bottom of each of the pair of jaws comprise individual zones. In an exemplary method, the top zones are heated to a higher temperature than the bottom zones. This is because higher temperatures are generally desirable to produce adequate end seals. However, lower temperatures are desirable in the bottom zones because that is where a gusset of the pouch is formed; if temperatures in the bottom zone are too high, the film sticks to itself in a phenomenon called “gusset tacking,” thereby preventing the pouch from opening.

After the end seals are applied, the film web moves to a “V” notcher, where a “V”-shaped notch is cut into the film web between pouches to facilitate forming and folding pouches downstream in production. A 1.5 inch V-notch is particularly suitable for providing a combination of folding and machineability.

The film is then moved through a series of feed rollers, where the pouch is automatically cut from the web. The pouch is cut off by a guillotine knife at its proper length and held in place by servo controlled vacuum plates to await insertion into corrugated trays by a pneumatic plunger.

FIG. 1is a perspective view of a plurality of cartons12on a conveyer14. Enclosures such as corrugated cardboard trays, boxes or cartons, formed in another area of the plant, are conveyed to the pouch inserter area. In an exemplary embodiment, cartons12are pushed onto conveyor14by line pressure. A backlog sensor stops cartons12from feeding in case of a backlog. Brackets15keep cartons12properly spaced and oriented.

FIG. 2is a perspective view of the cartons12ofFIG. 1having pouches16inserted therein. If cartons12are detected, the pouches16, formed as discussed above, are advanced to the inserter area. In the inserter area, a plunger ram block inserts an opened pouch16into each carton12. Each pouch16includes a floor and side walls formed from the stock non-wax-coated film. To make sure the pouch16is inserted properly, the plunger ram block flares out with use of air cylinders as it is inserted. In other words, a pulsed air blower may be provided on the plunger to reduce the tendency of pouches16to be pulled back out of the carton12when the plunger is retracted. The plunger ram retracts and releases the pouch16in the carton12. The pouched carton20then passes through a reject station. In this station, if a pouch16is not detected, the empty carton12is blown off by means of an air blast.

The pouch16has a rectangular bottom that closely fits the inside dimensions of the formed carton12. The pouch16preferably has no creases or film wrinkles to mar the display appearance. The inserted pouches16preferably remain erect in all four floor corners of the carton12.

In some embodiments, the pouched carton20is then indexed to the pouch flaring station to open the top of the pouch16. The flarer unit is a vertically reciprocating unit with flare fingers or rods that extend downward toward the interior of pouch16. After flaring, the flared, pouched carton20is indexed to the filling station22. Defective pouches16or cartons12are detected and rejected prior to the filling station22.

In an exemplary embodiment, the filling conveyor24is a single lane lugged chain conveyor that indexes the pouched cartons20through the various stages of the filling station22. A servo motor and camco gear drive the filling conveyor24. A main AC motor drives the forming ram and filler head26.

A servo motor lowers the filler head26into the pouched carton20for filling with a flowable, dairy-based product18such as molten, processed cheese. If the viscosity of the molten cheese product18changes, the speed of the lowering action can be changed. In an exemplary embodiment, the filler head26is a mechanically powered single piston that measures product18by volume. The filler head26has four basic functions in its operation. First, there is the fill piston reciprocation, which is accomplished by a shaft-mounted cam. The linkage contains a screw adjustment, which can increase or decrease the amount of fill piston travel, thus changing the volume of product18as required.

The adjustment is done by a push button from the console. The button activates a stepper motor and turns the adjustment screw. Optionally, it can be tied to a checkweigher and adjusted automatically from the weighed packages. The second function is a rotary spool valve located in the hopper base. It permits product flow from the hopper into the piston-cylinder on the suction stroke, then upon actuation allows the product to be pumped down through the nozzle. A photoeye sensor mounted ahead of the filling station22senses a pouched carton20. It engages a no-fill lockout feature if the sensor fails to sense a pouched carton20. The third function utilizes a double acting air cylinder to activate the rotary valve on the nozzle. Once the valve opens, the cheese product18is filled into the pouched carton20. The rotary valve is used with processed cheese. For cream cheese applications, a tapered nozzle may be used. A fourth function is an optional product agitator inside the hopper. The standard hopper is single-walled and comes with a one-piece cover. Alternatively, a two-wall hopper can be used, in which warm water can be run between the walls to prevent the cheese product18from cooling or setting. A two-piece hopper cover can be added for simplicity in setting the level of cheese product18in the hopper, especially during startup.

Once filled, the pouched carton20moves forward to the pouch folding station28.FIG. 3Ais a perspective view of an assembly of a first sweeper arm30with roller31and a pair of rocker arms32disposed over a pouched carton20filled with molten cheese product18.FIG. 3Bis a perspective view of first sweeper arm30folding down one side36of a top portion of a pouch16with roller31. Simultaneously, a pair of rocker arms32pulls out the ears34of the pouch20. As roller31of first sweeper arm30folds down a first side36of the top portion of the pouch16over the top of the cheese product18, the first side36of the pouch film sticks to the cheese product18.

Second sweeper arm38is positioned behind the assembly of rocker arms32. In an exemplary embodiment, plate39is attached at an end of second sweeper arm38to flatten the cheese product18and smooth the first side36of the pouch film on the pouched carton20in the next index position. In an exemplary embodiment, each of first sweeper arm30, second sweeper arm38, and the pair of rocker arms32pivots between the positions shown inFIGS. 3A and 3B.

In an exemplary embodiment, the pivotal motion of first sweeper arm30and second sweeper arm38is coordinated so that they move together. Thus, both first sweeper arm30and second sweeper arm38are in an “up” position inFIG. 3Aand both first sweeper arm30and second sweeper arm38are in a “down” position inFIG. 33. In an exemplary embodiment, first sweeper arm30and second sweeper arm38simultaneously act upon two adjacent pouched cartons20.

With first sweeper arm30, second sweeper arm38and pair of rocker arms32in the position shown inFIG. 3A, pouched cartons20are indexed through pouch folding station28. The film of each pouched carton20is folded as first sweeper arm30and pair of rocker arms32pivot to the positions shown inFIG. 3B. First sweeper arm30and pair of rocker arms32alternate between the positions shown inFIGS. 3A and 3Bas the plurality of pouched cartons20index through pouch folding station28. In the next index position, the pouched carton20then is contacted by plate39of second sweeper arm38to flatten and smooth the first side36of the pouch film.

FIG. 3Cis similar toFIG. 3Abut shows a sickle shaped embodiment of a rocker arm132.FIG. 3Dis similar toFIG. 3Bbut shows a sickle shaped embodiment of a rocker arm132. The shape of sickle rocker arms132assists in flaring out ears34of pouch16, thereby leading to more uniform shaping of ears34.

FIG. 4is a perspective view of a guide41folding down the second side40of a top portion of a pouch16. In an exemplary embodiment, guide41is connected to pouch folding station28at pivotal connection43, which allows some vertical movement of a bottom surface of guide41to accommodate irregularities in the filling of cheese product18. While guide41is depicted as a roller, it can also be a plate or other member, preferably one that allows for vertical motion of its bottom surface. After this step, a portion of the second side40overlaps the first side36of the top portion of the pouch16, thereby forming a top wall over cheese product18. A guide plate may be used to keep the top wall flat before the tamp sealing station42.

The folded pouch is then sent to a heat tamp sealing station42.FIG. 5is a perspective view of a tamper44in a raised position above a pouch16. In an exemplary embodiment, tamper44is a heated platen. In an exemplary embodiment, tamper44includes extensions for heated upper ear anvils46. Ears34of pouch16extend between upper ear anvil46and lower ear anvil48. In an exemplary embodiment, both upper ear anvil46and lower ear anvil48are heated, so that each ear34is sealed with heat from both the top and bottom sides of the ear34. Because pressure is provided on both sides of the ear34, a lower sealing temperature may be used compared with the temperature of tamper44. The temperature of heated ear anvils46,48is generally in the range of about 125-130° F. in one embodiment. In an exemplary embodiment, ear guides54fold down ears34as pouched cartons20are indexed past ear guides54.

FIG. 6is a perspective view of a tamper44in a lowered, sealing position on pouch16. Lap seal50is produced by the overlap of second side40over first side36of the top portions of pouch16over product18. A function of tamper44is to push down on the lap seal50, expel trapped air from the headspace of the pouch16, and apply heat to activate the lap seal50. The tamper44is actuated by means of an air cylinder52. Generally, higher sealing temperatures result in better sealing. However, higher temperatures can also cause distortion of lap seal50such as wrinkling and creasing. In some embodiments, a sealing temperature of about 220-265° F. is used. A temperature of about 275° F. may used without adverse effect if limited to a short dwell time. Tamper44is in the raised position shown inFIG. 5as pouched cartons20are indexed through heat tamping station42. When an unsealed pouched carton20is positioned under tamper44, tamper44is actuated to press down on lap seal50and ears34, as shown inFIG. 6. Tamper44is then raised to allow for indexing of the next pouched carton20.

The pouched cartons20are then discharged to a lidding operation, in which a lid is positioned over the top of the pouched carton20.FIG. 7is a perspective view of a lidding station56for applying lids58to sealed, pouched cartons20to form packages60. In the illustrated embodiment, the lids58are pre-formed. In another embodiment, the lids are provided as flat blanks that are then folded and glued to the pouched carton20on-line. In an exemplary method, a flat lid blank is positioned over a pouched carton20as the carton20is raised to meet the lid. As the pouched carton20continues to move upward, the sides of the lid are bent down over the pouched carton20. The lid is glued to the pouched carton20with hot-melt adhesive.

In an exemplary embodiment, six packages60are side-loaded into a corrugated case. Each package60, comprising a lidded, pouched, and sealed enclosure20, is flipped so that the top wall36,40is below the dairy based product18. In an example, the finished case is date coded and flipped over so that residual heat and product pressure further assist in forming the bond of lap seal50. Finally, the flipped cases are conveyed to a variable retention time (VRT) area, where they are cooled based on particular product requirements.