Abstract:
A method for packaging products, such as any solid or semi-solid product, utilizes a horizontal form, fill and seal (HFFS) system, coupled with a method for subjecting the packages to positive pressure differential while packaging. In the HFFS system, product receiving cavities are formed in a lower film, with each product being arranged in a respective cavity. The loaded product receiving cavities are positioned in a sealing unit, with an upper film above the product cavities. The sealing unit is closed and a lower chamber of the sealing unit is pressurized to force the lower film against the product, while the product abuts a standoff member, in order to remove existing headspace. After minimizing the headspace, a sealing head seals the upper film to the lower film about the product receiving cavities. Thereafter, the pressure is released, the sealing unit is opened and the package can be further processed.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention pertains to the art of packaging and, more particularly, to packaging solid and semi-solid products between upper and lower plastic films in a horizontal form, fill and seal (HFFS) system utilizing a positive pressure differential to minimize headspace. 
       BACKGROUND OF THE INVENTION 
       [0002]    Certainly, there exists various known packaging systems employed to package a wide range of products. Cardboard containers are commonly employed, mainly due to their overall structure which protects stored products from damage. By way of example, it is known to store a refrigerated dough product in a canister of a fixed volume formed from composite paperboard which is spirally wound into a cylinder so the refrigerated dough product proofs while in the canister. However, packaging products in cardboard is actually, relatively expensive and, at least in connection with products having a small profit margin, can be cost prohibitive. 
         [0003]    Although other types of packaging exist, at least a majority of these types of packages are simply not suited for certain products, such as refrigerated dough-based food products which require the control of headspace volume and composition. 
         [0004]    Mainly because of cost efficiencies and packaging versatility, vertical and horizontal form, fill and seal packaging systems have become increasingly popular, particularly in the food industry. While vertical form, fill and seal systems have mainly been limited in connection with making sealed bags, such as potato chip and other types of snack bags, horizontal form, fill and seal packaging systems are considered to be much more versatile. By way of example, it is known to employ a horizontal form, fill and seal (HFFS) system to form product cavities or pouches in a lower film, fill the pouches with frozen dough products and seal the products in the pouches with an upper film. Prior to fully sealing the pouches, a vacuum is typically drawn in order to reduce the available headspace of the package. Although evacuating the headspace is appropriate for frozen dough products, employing a vacuum on a refrigerated dough product would destroy nucleation sites for leavener in the dough and, consequently, the overall product. However, if no vacuum is drawn, the headspace will fill with carbon dioxide which will chemically react with deplete the dough of leavening gas and swell the package. 
         [0005]    Although the above discussion exemplifies disadvantages with utilizing an HFFS system with refrigerated dough products, numerous other products can be similarly affected. Certainly, the many advantages of utilizing HFFS systems make them enticing to employ. However, these advantages have mostly been outweighed by their disadvantages, at least with respect to particular products. To this end, there is seen to still exist a need for new ways of packaging various types of products, including refrigerated dough products, that can take advantage of the benefits of HFFS systems while avoiding known system drawbacks. 
       SUMMARY OF THE INVENTION 
       [0006]    The invention is directed to a method for packaging products, such as any solid or semi-solid product, utilizing a horizontal form, fill and seal (HFFS) system wherein packaged products are subjected to a pressure differential, without applying a vacuum, prior to sealing. According to the invention, the packaging method includes creating product receiving cavities in a lower film, loading product in the product receiving cavities and introducing the loaded product receiving cavities into a sealing unit of the horizontal form, fill and seal assembly with an upper film above the loaded product receiving cavities within the sealing unit. Thereafter, the sealing unit is closed about the loaded product receiving cavities and a lower sealing chamber of the sealing unit is pressurized to minimize a headspace between the product and the upper film. This stage includes forcing the product against standoffs positioned in the sealing unit while maintaining a gap between the upper and lower films to allow the gas in the headspace to escape into an upper, vented cavity. After removing the headspace, a sealing head is activated to seal the upper film to the lower film about the loaded product receiving cavities. After releasing pressure in the lower sealing chamber, the sealing unit is opened in order to allow the packaged product to be conveyed to another system station, such as a cutting station. 
         [0007]    With the above method, the problems associated with vacuum-based HFFS packaging systems are avoided and the range of products which can be packaged in accordance with the invention significantly increases. The invention is particularly adapted for use in packaging, refrigerated dough products as these products would actually be destroyed if a vacuum-based system were employed. When a relatively soft material, such as a refrigerated dough, is packaged with the system, the use of a positive pressure, without vacuum, advantageously enables the product to deform so as to take-up some headspace, a result which would be not be possible with a vacuum-based system. 
         [0008]    Additional objects, features and advantages of the invention will become more readily apparent from the following detailed description when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  schematically illustrates a horizontal form, fill and seal (HFFS) system which functions in accordance with the method of the invention. 
           [0010]      FIG. 2  is a cross-sectional view of the sealing unit incorporated in the HFFS system of  FIG. 1 , with the sealing chamber being in a partially open condition. 
           [0011]      FIG. 3  is a cross-sectional view of the sealing unit of  FIG. 2  in a closed state. 
           [0012]      FIG. 4  is a cross-sectional view of the sealing unit following pressurizing of a lower chamber of the sealing unit. 
           [0013]      FIG. 5  is a cross-sectional view of the sealing unit with heat seals being activated. 
           [0014]      FIG. 6  is a cross-sectional view of the sealing unit with the lower chamber pressure being released. 
           [0015]      FIG. 7  is a cross-sectional view of the sealing unit in a fully open condition. 
           [0016]      FIG. 8  is a perspective view of a dough product packaged in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0017]    With initial reference to  FIG. 1 , a horizontal form, fill and seal (HFFS) system employed in connection with the packaging method of the present invention is generally indicated at  2 . As shown, system  2  has associated therewith a first or lower film  5  which runs from a payout reel  7  in the direction of arrow A to a take-up reel  8 . As will become more fully evident below, the majority of film  5  is used in connection with packaging products in accordance with the invention and take-up reel  8  receives the left over or scrap film. In a preferred form of the invention, take-up reel  8  merely receives lateral edge portions of lower film  5 , such as an inch (approximately 2.54 cm) of either side of film  5  while the remainder of the film  5  is employed in the final package. In any case, lower film  5  is first directed to a heating station  10  and is directed between upper and lower heating units  12  and  13 . In general, heating station  10  can employ various types of heater units  12 ,  13  known in the art, such as radiant and/or convection heaters. Basically, it is simply desired to heat lower film  5  for delivery to forming station  18 . In forming station  18 , a thermoforming unit  19  is employed to produce product cavities  20  in lower film  5 . To this end, thermoforming unit  19  includes a lower cavity mold  21  having a main body  22  formed with recessed cavities  23 . A linear actuator  24  is connected to main body  22  and designed to vertically shift main body  22  during the forming of product cavities  20 . For use in connection with the forming process, fluid communication lines, such as that indicated at  25 , extend through main body  22  to recessed cavities  23 . In conjunction with lower cavity mold  21 , thermoforming unit  19  includes an upper cavity mold  30  which also includes a main body  31  from which extend various projection molds  32  that conform to recessed cavities  23 . In a manner similar to lower cavity mold  21 , upper cavity mold  30  is connected to a linear actuator  33  used to vertically shift upper cavity mold  30  during a thermoforming operation. 
         [0018]    In general, thermoforming devices such as that employed in connection with forming station  18  are widely known in the art and do not form part of the present invention. However, for the sake of completeness, it should at least be understood that the function of forming station  18  is to receive heated lower film  5  between lower cavity mold  21  and upper cavity mold  30  at which time the movement of lower film  5  is temporarily stopped, projection molds  32  are mated with recessed cavities  23  in order to reshape lower film  5  to include product cavities  20 . To aid in this shaping operation, fluid communication lines  25  can be hooked to a vacuum source in order to draw lower film  5  against recessed cavities  23  as well as to subsequently apply a positive pressure to aid in removing the formed product cavities  20  from lower cavity mold  21  after the thermoforming process is complete. 
         [0019]    Once product cavities  20  are formed in lower film  5 , lower film  5  advances to a loading or filling station generally indicated at  40 . At this point, it should be recognized that filling station  40  can take various forms without departing from the invention. As illustrated, filling station  40  includes a vertical loading unit  42  including a platform  43  from which extend various loading arms  44  used to transport products, such as that indicated at  46 , into the individual product cavities  20 . 
         [0020]    After products  46  are loaded into product cavities  20 , lower film  5  is advanced to a sealing station  52 . The present invention is particularly concerned with the manner in which products  46  are sealed within product cavities  20  such that details of sealing station  52  will be more fully described below. However, as is widely known in connection with standard 14FFS systems, a second or upper film  56  is drawn from a payout reel  57 . After following various guide rollers  63  to sealing station  52 , the remainder of upper film  56  is directed to a take-up reel  65 . At sealing station  52 , upper film  56  is sealed to lower film  5  across product cavities  20  in order to create an overall product package indicated at  68 . Thereafter, package  68  is directed to a cutter station  72  wherein a blade element  73  is shifted vertically through the use of a linear actuator  74  against an anvil member  75  in order to cut each package  68  from the overall web defined by the mated lower film  5  and upper film  56 . 
         [0021]    Reference will be now made to  FIG. 2  in detailing an embodiment of sealing station  52  in accordance with the invention. As shown, sealing station  52  employs a sealing unit  78  defined by a housing  80  including an upper housing portion  81  and a lower housing portion  82 . Housing  80  has associated therewith an inlet opening  85  and an exit opening  86 , each of which is only shown to be partially open in this figure. Basically, upper and lower housing portions  81  and  82  are adapted to be vertically shifted relative to each other by linear actuators (not shown) in order to vary the size of inlet and exit openings  85  and  86  in order to enable housing  80  to receive or discharge both lower film  5  with products  46  in product cavities  20  and upper film  56  as illustrated. Above upper film  56  within housing  80  is defined a vented, upper cavity  90 . Upper cavity  90  can be vented in various ways, such as with one or more vent ports (not shown) or forming upper housing portion  81  as an open framework. Below lower film  5  within housing  80  is defined a lower sealing chamber  91 . At least lower sealing chamber  91  in accordance with the invention is connected to a compressed fluid supply unit  93 , such as an air compressor, through a line  94 . 
         [0022]    Also arranged within housing  80  is a plurality of spaced standoffs  97 . In the embodiment shown, standoffs  97  are fixed relative to upper housing portion  81  and include plate members  98 , having substantially flat lower surfaces  99 , suspended within upper housing portion  81  through respective rods  100 . As clearly evident from viewing this figure, the number of standoffs  97  is commensurate with the number of product cavities  20  which are accommodated within sealing unit  78  for a given sealing cycle of HFFS system  2 . Also arranged within housing  80  is an upper sealing element  104  and a lower sealing element  105 . Upper and lower sealing elements  104  and  105  are vertically shiftable within upper and lower housing portions  81  and  82  respectively. However, for sake of clarity of the drawings, the linear actuators employed in connection with shifting upper and lower sealing elements  104  and  105  have not been depicted. In any case, upper and lower sealing elements  104  and  105  include various spaced, mating sealing arms, such as that indicated at  109  and  110 . As clearly evident, each set of sealing arms  109 ,  110  are positioned along a respective portion of each package  68 . Although not clearly shown in this figure due to the cross-section depicted, mating sealing arms  109  and  110  would extend around the entire periphery of each respective product cavity  20  and, as will be described further below, are used in sealing upper film  56  to lower film  5  and, consequently, a given product  46  in a respective cavity  20 . 
         [0023]    Reference will now be made to  FIGS. 2-7  in describing the operation of sealing unit  78  in connection with the present invention. As indicated above,  FIG. 2  depicts sealing unit  78  with inlet and exit openings  85  and  86  exposed. Correspondingly, housing  80  is partially open in  FIG. 2 . In  FIG. 3 , upper and lower housing portions  81  and  82  have been brought together such that inlet and exit openings  85  and  86  are fully closed, along with lower sealing chamber  91 . At this time, it should be at least noted that upper and lower sealing elements  104  and  105  are spaced from both upper film  56  and lower film  5 . Thereafter, the sealing operation proceeds to  FIG. 4  wherein compressed fluid supply unit  93  is activated to pressurize lower sealing chamber  91 . At this time, lower film  5  is forced upward within housing  81  which actually causes both upper film  56  and product  46  to be forced against a respective standoff  97 . This action is perhaps best depicted from seeing the manner in which product  46  converts from the rounded upper configuration shown in  FIG. 3  to a flat upper configuration in  FIG. 4 , while lower film  5  defining product cavity  24  is drawn about product  46 . At this point, it should be recognized that this deformation occurred in connection with the packaging of soft dough and relatively high pressure in sealing unit  78 . Therefore, dough deformation need not occur, such as when packing flat biscuits in a pouch. In any case, at the same time, the head space  116  (see  FIG. 3 ) within each product cavity  20  is minimized. Although both product  46  and upper film  56  are forced against a standoff  97 , the gas within headspace  116  is forced to flow between lower film  5  and upper film  56 . This gas flow can be enhanced in various ways, such as by pre-forming upper film  56  with various slits in the regions between product cavities  20  or by making upper film  56  narrower than upper cavity  90  such that the gas from headspace  116  will be free to flow into upper cavity  90 . As upper cavity  90  is vented, the gas is readily released. As the pressure within lower sealing chamber  91  is increased, lower film  5  is further forced against product  46  and the air in headspace  116  in between films  5  and  56  is expelled. 
         [0024]    In one form of the invention wherein product  46  constitutes a refrigerated dough product, lower sealing chamber  91  is preferably pressurized between 0.5 and 50 psi, more preferably, in the order of 25 psi for a large package and 2 psi for a small package. When a soft material is being packaged, such as a refrigerated dough, product  46  can actually deform as discussed above to take up some of the headspace  116 . At this point, it should be clearly noted that the pressure differential arrangement employed in connection with sealing unit  78  is done without a vacuum. In any case, after headspace  116  is minimized, the sealing operation proceeds to that shown in  FIG. 5  wherein upper and lower sealing elements  104  and  105  are brought together about product cavities  20  to seal lower and upper films  5  and  56 . Thereafter, the pressure within lower chamber  91  is released as shown in  FIG. 6 . At this point, products  46  are sealed inside the low volume product cavities  20 , upper and lower housing portions  81  and  82  are shifted relative to each other to expose inlet and outlet openings  85  and  86  as shown in  FIG. 7 , then the packaging operation proceeds to cutter station  72 . In accordance with a variant of the invention, package  68  can be further wrapped in a film (not shown) which is shrunk about the package  68 , such as by heating, thereby developing an applied force which is essentially transferred to static pressure within package  68 . 
         [0025]      FIG. 8  is a perspective view of package  68  following cutter station  72 . In the embodiment shown, the soft, low temperature dough product has generally taken a D-shape with a flat top due to the application of the pressure in connection with sealing unit  78 . Because of the use of the pressure method of the invention, the invention is only applicable for use in packaging relatively rigid objects, i.e., any solid or semi-solid object. That is, the invention can be employed in connection with any solid or rigid product, semi-solid product such as jello, but not liquids. However, it should be recognized that the invention could be employed in connection with the combination of a liquid with a solid so long as the liquid had a high enough viscosity and associated properties to prevent it from being squirted out between the upper and lower films during the pressurization phase. Therefore, in connection with at least the food art, other exemplary products can include jello, vegetables, overall meals and frozen products, while the use of the invention with rigid products can take various forms including medical products, toys, electronics and the like. Still, given the unique problems associated with refrigerated dough products, the fact that the present sealing arrangement of the present invention does not employ a vacuum provides significant advantages over a HFFS system which would either employ a vacuum or even a combination of a vacuum and positive pressure. In any case, although described with reference to embodiments of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. Instead, the invention is only intended to be limited by the scope of the following claims.