Abstract:
A method of sealing a package containing a food product is provided. The method comprises applying a lid to a non-planar flange surrounding a periphery of the food package. The method comprises supporting at least a portion of the non-planar flange and progressively sealing the lid to the supported portion of the non-planar flange by applying pressure at one or more tangent points against the lid and the flange using a sealing member having a pressure applying surface that rotates about an axis of rotation and one of radially varies relative to the axis of rotation and the axis of rotation reciprocates.

Description:
CROSS-REFERENCE TO RELATED APPLICATION APPLICATIONS 
     This application is a U.S. national phase application filed under 35 U.S.C. §371 of International Application PCT/US2013/029578, filed Mar. 7, 2013, designating the United States, which claims the benefit of U.S. Patent Appl. No. 61/608,080, filed Mar. 7, 2012, which are hereby incorporated by reference in their entirety. 
    
    
     FIELD 
     Systems and methods for sealing food product containers are described herein, and in particular, systems and methods for sealing food product containers having non-planar flanges. 
     BACKGROUND 
     Food product trays typically have planar or flat, symmetric seal flanges. Traditional sealing methods utilise a sealing surface that is applied in one plane that is immediately above the planar surface of the seal flanges. In addition, such methods typically utilize an equal length of lid film stock for a given length of the seal flange of the container such that the seal flange length is equal to its projected dimension on the original, unformed sheet. 
     The above described methods would not be effective to seal packages having flanges that do not lie in one plane, such as curved or non-planar flanges. For example, in a package with one or more curved flanges, the traditional methods of measuring and applying the lid film would not be feasible because the projected dimension of the seal flange would be less than the length along the curve of the sealing flange and a greater length of lid material would be needed for a corresponding length of the base package. In a package where a portion of the flange curves or otherwise deviates out of the flat plane, traditional methods would result in the curved flange remaining unsealed because the sealing surface would only applied in one plane and would not contact the curved portion of the seal flange. 
     A method of sealing a package containing a food product is provided. The method comprises applying a lid to a non-planar flange surrounding a periphery of the food package. The method comprises supporting at least a portion of the non-planar flange and progressively sealing the lid to the supported portion of the non-planar flange by applying pressure at one or more tangent points against the lid and the flange using a sealing member having a pressure applying surface that rotates about an axis of rotation and one of radially varies relative to the axis of rotation and the axis of rotation reciprocates. 
     The step of supporting at least a portion of the non-planar flange can further include supporting the flange along its entire surface during the step of progressively sealing the lid. 
     The step of supporting at least a portion of the non-linear flange can further include supporting the flange using a flange support surface that rotates about an axis of rotation. The axis of rotation of the flange support surface can be parallel to the axis of rotation of the pressure applying surface. 
     The non-planar flange can advance in a linear direction perpendicular to the axis of rotation of the pressure applying surface. 
     The non-planar flange can have a projected length in a machine direction of less than a length along she flange in the machine direction. 
     The method can further a step of tacking a portion of the lid to a leading end of the non-planar flange. 
     The method can include sealing a portion of the lid to a leading end of the flange in a first plane and sealing another portion of the lid to a trailing end of the flange in a second plane. 
     The method of can further include a step of transporting the package along a conveyor surface with a portion of the lid attached to the non-planar flange and a portion of the lid unattached to the non-planar flange. 
     The method can further include providing a plurality of at least one seat including a cavity configured to receive the package with the flange being at least in part outside of the cavity. 
     The method can further include a step of providing at least one cylindrical top sealing member having at least one sealing surface configured to rotate and contact the non-planar flange to seal the lid to the package. 
     The method can also include providing two cylindrical top sealing members where one of the sealing members seals one portion of the lid to one portion of the non-planar flange and the other of the sealing members seals another portion of the lid to another portion of the non-planar flange. The method can further include rotating the two cylindrical sealing members at different speeds. 
     The method can also include a step of providing a bottom rotary die having a plurality of seats, each seat having a plurality of support surfaces configured to support the non-planar flange, and a top rotary sealing member having a plurality of sealing surfaces configured to rotate and contact the support surfaces of the seats to seal the lid to the package. 
     The method can also include a step of providing a conveyor surface including a plurality of seats, each seat having a plurality of support surfaces configured to support the non-planar flange, and a top rotary sealing member having a plurality of sealing surfaces configured to rotate over and contact each of the support surfaces to seal the lid to the package. 
     The method can further include applying the lid onto the flange using a pick and place device including a vacuum. 
     The method can further include a step of providing the sealing member having the sealing surface that is entirely non-planar. 
     The method can further include a step of applying the lid onto the flange from a supply film roll using a plurality of rollers, at least one of the rollers including a cutting surface. 
     The method can further include placing and sealing the lid onto the non-planar flange at one station. 
     The method can further include creating a pressure atmosphere in the package that urges the lid in a direction away from the food product stored in the package. 
     The method can also include creating a protective atmosphere in the food package to increase a shell life of the food product stored in the package. 
     The lid can be made of a flexible film or can be made of a rigid material, such as a suitably rigid blow-molded, injection molded or thermoformed plastic. 
     The method can further comprise providing a food storage package having a non-planar flange. The package can have a top surface that is entirely non-planar. The package can alternatively have a bottom surface that is in part planar and in part non-planar. The package can include a tray having a non-planar flange. 
     The method can include a step of using the sealing member having a sealing surface that radially varies relative to the axis of rotation. 
     The method can include a step of using the sealing member having an axis of rotation that reciprocates. 
     A package including a non-planar flange made according to any one of aforementioned methods is also provided. The package can include a tray having a non-planar flange. 
     An apparatus for sealing a lid to a non-planar flange surrounding a periphery of a package containing a food product is provided. The apparatus includes a conveyor surface configured to advance the package. The apparatus further includes a bottom rotary die protruding at least in part above the conveyor surface and having a plurality of seats, each seat having a plurality of support surfaces configured to support at least a portion of the non-planar flange. The apparatus also includes at least one top sealing member having at least one sealing surface configured to rotate and contact the non-planar flange to seal the lid to the flange. 
     The at least one top sealing member can rotate about a reciprocating axis of rotation to seal the lid to an entire surface of the flange. 
     The at least one top sealing member can comprise two top sealing members each configured to rotate about a reciprocating axis of rotation to seal the lid to the flange. 
     The at least one top sealing member can include a first top sealing member configured to seal one portion of the lid to one portion of the flange and a second top sealing member configured to seal another portion of the lid to another portion of the flange. 
     The top sealing member can comprise a plurality of sealing surfaces and is configured to rotate about one axis of rotation and contact each of the support surfaces of the seats to seal the lid to the package. 
     Another apparatus for sealing a lid to a non-planar flange surrounding a periphery of a package containing a food product is also provided. The apparatus comprises a conveyor configured to advance the package. The conveyor includes a plurality of seats formed thereon having a plurality of support surfaces configured to support the non-planar flange. The apparatus further includes at least one top sealing member having at least one sealing surface configured to rotate and press the lid against the flange. 
     The top sealing member can comprise a plurality of sealing surfaces and is configured to rotate about one axis of rotation and contact each of the support surfaces of the seats to seal the lid to the package. 
     The at least one sealing surface can be non-planar. The at least one sealing surface can be made of a resilient material. 
     The apparatus can further comprise a device configured to transfer the lid from a supply source and apply the lid onto the flange of the package. The device can comprise a vacuum source configured to lift and move the package. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a first exemplary container having one or more non-planar flanges shown without a lid; 
         FIG. 2  is a perspective view of the container of  FIG. 2  shown with a food product in the hollow interior of the container; 
         FIG. 3  is the container of  FIG. 1  shown sealed with a lid; 
         FIG. 4  is a side elevational view of the container of  FIG. 1 ; 
         FIG. 5  is a perspective view of a second exemplary container having one or more non-planar flanges shown without a lid; 
         FIG. 6  is a perspective view of the container of  FIG. 5  shown with a food product in the hollow interior of the container; 
         FIG. 7  is the container of  FIG. 5  shown sealed with a lid; 
         FIG. 8  is a side elevational view of the container of  FIG. 5 ; 
         FIG. 9  is a front elevational view of the sealed container of  FIG. 7 , shown being positioned in a vertical orientation; 
         FIG. 10  is a perspective view of a first exemplary conveyor system for sealing the container of  FIG. 1 ; 
         FIG. 11  is a perspective enlarged fragmentary view of the conveyor system of  FIG. 10 , showing the tacking station for tacking a lid to the leading seal flange of the containers; 
         FIG. 12  is a side elevational view of the tacking station of  FIG. 11 ; 
         FIG. 13  is a top plan view of the conveyor system of  FIG. 10 ; 
         FIG. 14  is a side elevational view of the conveyor system of  FIG. 10 ; 
         FIG. 15  a front perspective enlarged fragmentary view of the conveyor system of  FIG. 10 , showing the sealing station for sealing a lid to the seal flanges of the containers; 
         FIG. 16  a rear perspective enlarged fragmentary view of the conveyor system of  FIG. 10 , showing the sealing station for sealing a lid to the seal flanges of the containers; 
         FIG. 17  is a perspective view of a second exemplary conveyor system for sealing the container of  FIG. 1 ; 
         FIG. 18  is a top plan view of the conveyor system of  FIG. 17 ; 
         FIG. 19  is a side elevational view of the conveyor system Of  FIG. 17 ; 
         FIG. 20  is a side perspective enlarged fragmentary view of the conveyor system of  FIG. 17 , showing the mating of the top and bottom rotary sealing members of the sealing station to seal the lid to the leading seal flange of the container of  FIG. 1 ; 
         FIG. 21  is a side perspective enlarged fragmentary view of the conveyor system of  FIG. 17 , showing the mating of the top sealing member and the bottom rotary die of the sealing station to seal the lid to the trailing seal flange of the container of  FIG. 1 ; 
         FIG. 22  is a front perspective enlarged fragmentary view of the conveyor system of  FIG. 17 , showing the top sealing member and the bottom rotary die of the sealing station separated and the lid fully sealed to the seal flanges of the container of  FIG. 1 ; 
         FIG. 23  is a perspective view of a third exemplary conveyor system for sealing the container of  FIG. 1 ; 
         FIG. 24  is a top plan view of the conveyor system of  FIG. 23 ; 
         FIG. 25  is a side elevational view of the conveyor system of  FIG. 23 ; 
         FIG. 26  is a perspective fragmentary view of the conveyor system of  FIG. 23 , showing the mating of the top sealing member and the die train of the conveyor; 
         FIG. 27  is a front perspective enlarged fragmentary view of the conveyor system of  FIG. 23 , showing the mating of the top rotary sealing member and the seat of the die train to seal the lid to the leading seal flange of the container of  FIG. 1 ; and 
         FIG. 28  is a rear perspective enlarged fragmentary view of the conveyor system of  FIG. 23 , showing the mating of the top rotary sealing member and the seat of the die train to seal she lid to the trailing seal flange of the container of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A system and method for sealing of packages having one or more curved, non-planar sealing flanges are provided. The method includes advancing the package having a non-planar seal flange on a conveyor belt in a machine direction. An optional tacking station is located upstream of the sealing station on the conveyor. The tacking station can include a lid material supply roller and plurality of rollers and/or dies which transfer the lid material from the supply roller, out the lid material, tack the lid material to the leading seal flange of the package, and align the lid material over the other seal flanges. The package, with the lid material being tacked to the leading seal flange, can be advanced along the conveyor to a sealing station. 
     The method also includes creating a single point of contact, or nip point, and allowing the lid material to coincide with and follow the non-planar length of the package instead of the projected length of the seal flange to seal the lid material to the seal flanges. This can be accomplished by utilizing one or more rotary sealing members. The method further can include moving a rotary top sealing member and the package in coordination so as to keep a sealing force constantly perpendicular to the tangent of contact. The system and method will be discussed in greater detail herein following a description of exemplary packages. 
     With reference to  FIGS. 1-4 , an exemplary container  100  having non-planar seal flanges is provided. The term non-planar flange will be understood to mean a flange having a first surface in one plane and a second surface in a different plane. The non-planar flange could be entirely curved, could be curved in part and straight in part, or could have two or more straight portions that are angled relative to one another. 
     The container  100  can be used to store a food product  130  as shown in  FIG. 2 . The food product  130  can be crackers, cookies, wafers, chocolates, candy, or the like. The food product  130  can be stored in one or more stacks or rows as shown in  FIG. 2 , or may be dump-filled into the container  100 . The container  100  can be made of a flexible material including, but not limited to polyethylene, polypropylene, or the like. For example, the container  100  can be thermoformed, injection-molded, blow-molded, or the like. The container  100  can also be laminated and optionally include a metalized layer. A lid  134  may be sealed to the container  100  as shown in  FIG. 3  to provide the container  100  with a hermetic seal. The lid  134  can be flexible or rigid. 
     With reference to  FIGS. 1 and 4 , the exemplary container  100  can have a bottom wall  116 , a front wall  117 , two opposed side walls  118  and  120 , and a hollow interior  119  therebetween. The container has a leading end  110  (in the machine downstream direction), a trailing end  111  opposite the leading end  110 , a bottom surface  112 , and a top surface  114  opposite the bottom surface  112 . The container  100  does not have a rear wall opposite the front wall  117 . Instead, the container  100  has an open area at the trailing end  111 . This open area can be used to unload the food product  130  stored in the hollow interior  119  of the container  100  onto a serving surface such as a tray or a plate. Optionally, a rear wall opposite the front wall  117  could be provided. 
     The container  100  includes a leading seal flange  102 , a trailing seal flange  104 , and side seal flanges  106  and  108 . The leading flange  102  and adjacent portions of the side flanges  106  and  108  are flat and lie in the same horizontal plane, together defining the top surface  114  of the container  100 . Portions of the side seal flanges  106  and  108  can curve or deviate in a straight line or otherwise downward from the top surface  114  toward the trailing seal flange  104 . As such, the leading flange  102  and the trailing flange  104  lie in different planes as shown in  FIG. 1 . Indeed, the different planes including the leading and trailing seal flanges  102  and  104  are angled relative to each other as can be seen in  FIG. 4 . Similarly, the trailing flange  104  and portions of the side flanges  106  and  108  also lie in different planes. The non-planar shape of the sealing flanges of the container  100  provides the container  100  with a distinctive and aesthetically pleasing appearance. 
     With reference to  FIG. 4 , a portion of the leading end  110  of the container  100  can be straight and perpendicular to the top surface  114 . The leading seal flange  102  protrudes beyond and overhangs the leasing end  110 . A curved transition  113  is formed between the leading end  110  and the bottom surface  112  of the container  100 . The portion of the bottom surface  112  proximate the curved transition  113  can be planar or flat and can be parallel to the top surface  114 . The flat portion of the bottom surface  112  of the container  100  allows the container  100  to be stable when positioned on a flat surface such as a shelf or a table. 
     Proximate the trailing end  111  of the container  100 , the bottom surface  112  of the container  100  can curve or linearly deviate upward to form a raised portion  115 . This non-planar shape of the bottom surface  112  does not undermine the stability of the container  100  when positioned on a flat surface such as a shelf because a majority of the bottom surface  112  is flat. The raised portion  115  can act as stop for the circular food product  130  stored in the hollow interior  119  of the container  100 , and can prevent she food product  130  from inadvertently rolling out of the container  100 . 
     With continuing reference to  FIG. 4 , the non-planar portions of the side flanges  106  and  108  define the trailing end  111  of the container  100 . The trailing end  111  can be curved in part or in its entirety. The trailing end  111  of the container  100  terminates in the trailing seal flange  104 , which extends slightly below the raised portion  115  of the bottom surface  112  of the container  100 . 
       FIGS. 5-9  illustrate a second exemplary container  200  having one or more non-planar seal flanges. Similar to the container  100 , the container  200  can be used to store a food product  230 , as shown in  FIG. 6 . The container  100  can be made of a flexible material including, but not limited to polyethylene, polypropylene, or the like. The container  200  can be laminated and optionally include a metalized layer. For example, the container  200  can be thermoformed, injection-molded, blow-molded, or the like. A lid  234  may be sealed to the container  200  as shown in  FIG. 6  to provide the container  200  with a hermetic seal. The lid  234  can be flexible or rigid. 
     With reference to  FIGS. 5 and 8 , the container  200  can have a bottom wall  216 , a front wall  217 , two opposed side walls  218  and  220 , and a hollow interior  219  therebetween. The container  200  also includes a leading seal flange  202 , a trailing seal flange  204 , and side seal flanges  206  and  208 . The leading seal flange  202  can include a tab portion  222  which facilitates the user in peeling off or otherwise removing the lid  234  when opening the container  200 . 
     Similar to container  100  the container  200  does not have a rear wall opposite the front wall  217 . Instead, the container  200  has an open area between the seal flanges  202 ,  204 ,  206 , and  208 . This open area can be used to load and/or unload the food product  230  into and out of the container  200 . Optionally, a rear wall opposite the front wall  217  can be provided. The hollow interior  219  of the container  200  can store the food product  230  in one stack as shown in  FIG. 6 , or can store a loose food product that can be dump-filled, for example, candy, chips, nuts, or raisins. 
     With reference to  FIG. 8 , the container  200  has a leading end  210  (in the machine downstream direction), a trailing end  211  opposite the leading end  210 , a bottom surface  212 , and a top surface  214  opposite the bottom surface  212 . The leading seal flange  202  can protrude beyond and overhang the leading end  210  of the container  200 . The trailing end  211  of the container  200  terminates in a trailing flange  204 . 
     With reference to  FIG. 8 , the bottom surface  212  of the container  200  proximate the trailing end  211  can curve or deviate in a straight line or otherwise upward to form a raised portion  215 . The trailing seal flange  204  can extend slightly beyond and overhang the raised portion  215  of the bottom surface  212 . The non-planar shape of the bottom surface  212  does not undermine the stability of the container  200  when positioned on a flat surface. Instead, the protruding trailing seal flange  204  and the non-planar shape of the bottom surface  212  can create a point of stability for the container  200  when positioned on a flat surface such as a shelf or table. In addition, the raised portion  215  of the bottom surface  212  can create a stop for the circular food product  230  and can restrict the food product  230  from inadvertently rolling out of the container  200 . 
     The side flanges  206  and  208  of the container  200  can be non-planar in part or in their entirety from the leading seal flange  202  to the trailing seal flange  204 . As such, the top surface  214  of the container  200  can be non-planar in part or in its entirety. Similarly, the bottom surface  212  of the container  200  can be non-planar in part or in its entirety from the leading seal flange  202  to the trailing seal flange  204 . As such, the container  200  can have a non-planar leading end  210  and a non-planar trailing end  211 . The non-planar shapes of the side flanges  206  and  208  and of the bottom and top surfaces  212  and  214  provide the container  200  with a distinctive and aesthetically appealing appearance. 
     The container  200  can also be positioned a standing orientation, as shown in  FIG. 9 . The non-planar shape of the side flange  206  and the exterior surface of the side wall  213  can create one or more points of stability for the container  200  on a flat surface. The lid  234  may include branding information that is oriented vertically (i.e., going from left to right in the direction from the trailing seal flange  204  to the leading seal flange  202 ) so that the container  200  can foe offered for sale on store shelves in the distinctive standing orientation. 
     With reference to  FIGS. 10-16 , a conveyor system  300  and method of applying and sealing a lid to the container  100  will now be described. It will be appreciated that this and any of the systems and methods described below can be advantageously used to seal the aforementioned container  200 , or any other container having one or more non-planar seal flanges. 
       FIG. 10  illustrates a conveyor system  300  advancing a plurality of food storage containers  100  in the machine direction indicated by an arrow. The conveyor system  300  includes a tacking station  330  and a sealing station  370 . Generally, as a container  100  passes through the tacking station  330 , a lid or cover is placed onto the container  100 , and when the container  100  passes through the sealing station  370 , the lid is sealed to the seal flanges  102 ,  104 ,  106 , and  108  of the container  100  to provide a cover and hermetic seal for a food product stored in the container  100 . 
     With reference to  FIGS. 10-12 , the tacking station  330  includes a supply roller  332  which includes the lid material  334 . The lid material  334  can be made from a thin, flexible material, such as a polymer film or laminate, foil, or the like. Alternatively, the lid material  334  can be made from a more rigid material. The lid material  334  can be unwound from the supply roller  332  in the machine direction as a continuous web  335  and is fed via a series of intermediate rollers  338 ,  340 ,  342 ,  344 , and  346  in between a die roller  348  and a vacuum roller  350 . The die roller  348  may include a cutting surface which may be indexed relative to the rotation speed of the die roller  348  such that a piece of lid material  334  of appropriate length to cover the seal flanges  102 ,  104 ,  106 , and  108  of the container  100  may be cut off from the continuous web  335  by the combined action of the action of the die roller  348  and the vacuum roller  350 . 
     The vacuum roller  350  has an axis of rotation that can be parallel to the axis of rotation of the supply roller  332 . The axis of rotation of the vacuum roller  350  can also be parallel to the conveyor surface  312  on which the containers  100  travel. The vacuum roller  350  can rotate in a direction opposite to the machine direction. In support member having a plurality of elongate arms  352  rotates beneath the conveyor surface  312  in the machine direction. As the support member rotates, the support arms  352  extend above the conveyor surface  312  as shown in  FIGS. 11 and 12 . 
     As a container  100  moves in the machine direction along the conveyor surface  312 , the vacuum roller  350  applies the lid material  334  onto the leading seal flange  102  of the container  100 . As the lid material  334  is being applied by the vacuum roller  350  to the leading seal flange  102  of the container  100 , the support arm  352  rotates into a position where the support arm  352  is substantially perpendicular to the leading seal flange  102 , as shown in  FIG. 11 . In this position, the support arm  352  may be in contact with the underside of the leading seal flange  102 , or may be slightly below the underside of the leading seal flange  102 . The leading flange  102  gets tacked or nipped between the bottom surface of the vacuum roller  350  and the upper surface of the support arm  352  as shown in  FIG. 11 . Since the container  100  and the leading flange  102  are flexible, the support arm  352  ensures that the leading seal flange  102  does not bend or break when a sealing force is applied to the leading flange  102  by the vacuum roller  350 . 
     After the vacuum roller  350  applies the lid material  334  to the leading seal flange  102  of the container  100 , the container  100  moves further in the machine direction along the conveyor surface  312  such that side seal flanges  105  and  108  of the container  100  pass under the vacuum roller  350 . Since portions of the side flanges  106  and  108  are in the same plane as the leading flange  102 , the roller  350  can align the lid material  334  to the side flanges  106  and  108  as shown in  FIG. 12 . 
     During the application of the lid material  334  to the side seal flanges  106  and  108 , the container  100  moves forward and the support arm  352  rotates forward such that the support arm  352  can be maintained in contact with the leading end  110  of the container  100 . The support arm  352  can thus act as a back stop for the container  100  as the lid material  334  is being applied to the side flanges  106  and  108  by the vacuum roller  350  to restrict the container  100  from being inadvertently moved out of position due to the force being applied by the vacuum roller  350 . Since the trailing flange  104  of the container  100  is non-planar and extends below the plane where the leading seal flange  102  lies, the bottom surface of the vacuum roller  350  does not contact the trailing seal flange  104  and the lid material  334  remains unattached to the trailing seal flange  104  when the container  100  exits from the tacking station  330 , as shown in  FIG. 12 . 
     Either or both the underside of the lid material  334  and the upper surface of the leading flange may have an adhesive layer. As such, when the container  100  exits the tacking station  330 , the lid material  334  can be partially attached by an adhesive to the leading seal flange  102  and/or the side seal flanges  106  and  108 . Thus, although the lid material  334  is not attached to the trailing seal flange  104  and not fully sealed to any of seal flanges  102 ,  106 , or  108 , the lid material  334  does not shift or fail off the container  100  as the container  100  moves along the conveyor surface  312  toward the sealing station  370 . 
     It is to be appreciated that instead of the tacking station  330  shown in  FIG. 1 , the conveyor system  300  may include a tacking station with a pick and place device. For example, the tacking station would include a stack of pre-cut sheets of flexible lid material  334  or sheets or stacks of rigid lid material  334  sized and shaped to match the size and shape of the seal flanges  102 ,  104 ,  106 , and  108  of the container  100 . The tacking station would further include a pick and place device which could pick a sheet of lid material  334  off the stack and transfer the sheet of lid material  334  onto a container  100  moving along the conveyor surface  312 . For example, the pick and place device could be vacuum-based and could have one or more points of contact with the lid material  334 . The pick and place device could apply a pressure to the top of the leading seal flange  102  similar to the vacuum roller  350  such that the sheet of lid material  334  placed onto the container  100  by the pick and place device would be tacked to at least the leading seal flange  102  to ensure that the lid material  334  does not inadvertently fail off the container  100  as the container  100  moves along the conveyor surface from the tacking station to the sealing station  370 . 
     It is to be appreciated that a tacking station such as the tacking station  330  can foe eliminated altogether and flexible or rigid lid material  334  can be transferred from a supply roll or supply stack directly onto the containers and sealed to the seal flanges of the containers  100  in one step at the sealing station  370 . In this approach, the containers  100  having partially attached lid material  334  would not travel along the conveyor surface  312  between the tacking station  330  and the sealing station  370 . Instead, open containers  100  having no lid material  334  applied to them would travel along the conveyor surface  312  until they reach the sealing station  370 , where the lid material  334  would foe applied to the containers  100  for the first time and the containers  100  would be sealed. 
     With reference to  FIG. 10 , at the sealing station  370 , the conveyor surface  312  has a gap and a portion of a bottom rotary die  360  rotates in the gap and protrudes above the conveyor surface  312 . Two top rotating dies or sealing members  366  and  368  rotate over the bottom rotary die  360 . The bottom rotary die  360  can have a fixed axis of rotation and rotates in the machine direction. The bottom rotary die  360  includes a plurality of die seats  362 . Each die seat  362  includes a cavity sized and shaped to receive the containers  100 . Each die seat  362  also includes a plurality of support surfaces  363 ,  365 ,  367 , and  369  configured to oaten the shape and orientation of the leading, trailing, and side seal flanges  102 ,  104 ,  106 , and  108  of the container  100 . 
     As the containers  100  move in the machine direction down the conveyor surface  312 , a portion of the container  100  passes a trailing edge  314  of a section of the conveyor surface  312  and the container  100  is deposited into the cavity of a die seat  362  of the bottom rotary die  360  as shown in  FIG. 15 . The container  100  may either be deposited into the die seat  362  of the bottom die  360  solely due to the forward motion of the conveyor surface  312 , or may be assisted by a push from behind by one of the raised ribs  313 , which can be positioned along the conveyor surface  312  at equal or son-equal intervals. 
     The container  100  is positioned in the die seat  362  such that only the seal flanges  102 ,  104 ,  106 , and  108  protrude from the cavity formed in the die seat  362 . In particular, the seal flanges  102 ,  104 ,  106  and  108  of the container  100  rest on the support surfaces  363 ,  365 ,  367 , and  369 , respectively, of the die seat  362 . As shown in  FIGS. 15 and 16 , a rubber or plastic insert  364  may surround the support surfaces  363 ,  365 ,  367 , and  369  of each seat  362  to compensate for variations in material and machine orientations. 
     The top rotating sealing members  366  and  368  can be cylindrical and can each have an axis of rotation parallel to the axis of rotation of the bottom rotary die  360 . The first top die  366  has a surface configuration such that the width of the die surfaces  366   a  and  366   b  protruding from the top die  366  generally match the widths of the side seal flanges  106  and  108 , respectively, of the container  100 . The second top die  368  has a surface configuration such that the width of the die surface  368   a  protruding from the die  368  generally matches the widths of the leading and trailing seal flanges  102  and  104  of the container  100 . Optionally, instead of the cylindrical sealing member  366  having sealing surfaces  366   a  and  366   b  that seal the lid material  334  to the side seal flanges  106  and  108  and the cylindrical sealing member  368  having a sealing surface  368   a  that seals the lid material  334  to the leading and trailing flanges  102  and  104 , the conveyor system  300  can include a single top die or sealing member having one or more sealing surfaces configured to seal each of the leading, trailing, and side flanges  102 ,  104 ,  106 , and  108  of the container  100 . 
     As such, when a container  100  received in a seat  362  of the bottom rotary die  360  passes under first top die  366 , the top die  366  seals the lid material  334  to the side flanges  106  and  108  of the container  100 . In particular, as the container  100  moves in the seat  362  of the bottom rotary die  360  under the top die  366 , the top die  366  rolls over the side flanges  106  and  108  such that the lid material  334  and the first and second side seal flanges  106  and  108  of the container  100  are nipped between the die surfaces  366   a  and  366   b  of the top die  366  and the support surfaces  367  and  369  of the seat  362  of the bottom die  360 . Since the top die  366  applies sealing pressure against the flexible side seal flanges  106  and  108  of the container  100 , the support surfaces  367  and  369  of the seat  362  provide support to and prevent the bending and/or breaking of the side seal flanges  106  and  108 , respectively, similarly to the support arm  352  at the tacking station  330 . 
     After the seat  362  of the bottom die  360  passes under the top die  366  and the lid material  334  is sealed to the side flanges  106  and  108  of the container  100 , the seat  362  travels under the second top die  368 . The second top die  368  seals the lid material  334  to the leading and trailing seal flanges  102  and  104  of the container  100 . In particular, as the container  300  passes under the top die  368 , first the lid material  334  and the leading seal flange  102  are nipped between the die surface  368   a  of the top die  368  and the support surface  363  of the seat  362  of the bottom die  360 . 
     Then, the lid material  334  and the trailing flange  104  of the container  100  are nipped between the die surface  368   a  and the support surface  365  of the seat  362  of the bottom die  360 . Since the top die  368  applies sealing pressure against the side flanges  106  and  108  of the container  100 , the support surfaces  363  and  365  of the seat  362  provide support to and prevent the bending and/or breaking of the leading and trailing seal flanges  102  and  104  of the container  100 , respectively, similarly to the support arm  352  at the tacking station  330 . 
     Since the support surfaces  367  and  369  of the seat  362  as well as the side flanges  106  and  108  are non-planar, the first and second top sealing members  366  and  368  and their respective sealing surfaces  366   a ,  366   b , and  368   a  do not move only about the initial axes of rotation of the top sealing members  366  and  368 . In particular, as the die surfaces  366   a ,  366   b , and  368   a  of the top sealing members  366  and  368  travel along the respective sealing flanges  102 ,  104 ,  106 , and  108 , the top sealing members  365  and  368  can travel both in an upward direction relative to their initial axes of rotation and in a downward direction relative to their initial axes of rotation. As such, each sealing member  366  and  368  has a variable axis of rotation which can reciprocate, and the relative position of the container  100  and the top sealing members  366  and  368  can vary as the lid material  334  is being sealed to the container  100 . 
     The rotational speed of the bottom rotary die  360  and the top sealing members  366  and  368  may be constant during the sealing of the lid material  334  to the container  100 . Alternatively, the rotational speed of either one or both the top sealing members  366  and  368  may vary during the sealing of the lid material  334  to the container  100 . 
     The top sealing members  366  and  368  can apply a sealing pressure in a direction that is normal to the seal flanges  102 ,  104 ,  106 , and  108  of the container  100 . More specifically, the bottom surfaces of the top sealing members  366  and  368  can apply a sealing force that is perpendicular to a line tangential to the non-planar seal flanges  102 ,  104 ,  106 , and  108  of the container  100 . This can provide for a smoothing action that can eliminate undesired wrinkling of the lid material  334  as it is being applied to the container  100 . Any wrinkles upstream of the sealing point of contact can be eliminated by the top sealing members  366  and  368  as a seal is made at the next sealing point, especially since the sealing surfaces  366   a ,  366   b , and  368   b  of the top sealing members  366  and  368  travel continuously along the surfaces of the seal flanges  102 ,  104 ,  106 , and  108  from the leading end  110  to the trailing end  111  of the container  100 . 
     With reference to  FIG. 15 , after the second top die  368  seals the lid material  334  to the trailing flange  104  of the container  100 , the container  100  is transferred back to the conveyor surface  312 . In particular, the leading end  316  of the conveyor surface  312  can have a loading platform  317  extending in a direction toward the bottom rotary die  360 . The loading platform  317  may have an upper surface  318  that is in the same horizontal plane as the conveyor surface  312 . Alternatively, the upper surface  318  of the loading platform  317  may be above or below the conveyor surface  312 , or may be angled relative to the conveyor surface  312 . The loading platform  317  can have a leading edge  319 . 
     As the seat  362  with a fully sealed container  100  is rotated by the bottom die  360  toward the loading platform  317 , the leading edge  319  of the loading platform  317  can lift the leading seal flange  102  from the support surface  363  of the seat  362  of the bottom die  360 . With the leading flange  102  being lifted, the forward motion of the bottom die  360 , can urge the trailing flange  104  and the side flanges  106  and  108  of the container  100  to be lifted off the remaining support surfaces  365 ,  367 , and  369 , respectively, such that the container  100  can be ejected from the seat  360  and transferred onto the loading platform  317 . The loading platform  317  can be shorter than the container  100  and as such, when the sealed container  100  is transferred onto the loading platform  317 , a portion of the container  100  comes in contact with and is pushed onto the leading edge  316  of the downstream section of the conveyor surface  312 . 
     The conveyor surface  312  can be made from a material that has sufficient friction with the container  100  such that when a portion of the container  100  sits on or is in contact with the conveyor surface  312 , the container  100  can be pulled onto the conveyor surface  312 . If the flat portion of the conveyor surface  312  does not pull the container  100  off the loading platform  317 , one of the raised ribs  313  may facilitate the transfer of the container  100  from the loading platform  317  onto the conveyor surface  312 . Once back on the conveyor surface  312 , the containers  100  can travel along the conveyor surface  312  coward a packing or accumulating station such as known in the art. 
     With reference to  FIGS. 17-22 , a second embodiment of a conveyor system  400  and method for applying a lid to the container  100  will now be described. Similarly to the first conveyor system  300 , the second conveyor system  400  can be used to seal the container  200  or any other container having one or more non-planar seal flanges. 
     The conveyor system  400  includes a tacking station  430  and a sealing station  470 . As the containers  100  pass through the tacking station  430 , lid material  434  is placed onto the containers  100 , and as the containers  100  pass through the sealing station  470 , the lid material  434  is sealed to the containers  100  to provide a cover and hermetic seal for the food product stored in the containers  100 . 
     The tacking station  430  is identical to the tacking station  430  described with reference to conveyor system  300  and will not be separately described here, but like reference numerals will be used to designate like parts. Instead of the tacking station  430  shown in  FIG. 17 , the conveyor system  400  may include a tacking station with a pick and place device as described above in reference to the tacking station  330 . 
     As the containers  100  exit the tacking station  430  with the lid material.  434  tacked to the leading seal flange  102 , they travel in the machine direction toward the sealing station  470 . At the sealing station  470 , the section of the conveyor surface  412  has a gap and a bottom rotary die  460  rotates in the gap and protrudes above the conveyor surface  412 . The bottom rotary die  460  is identical to the bottom rotary die  360  described above in reference to the conveyor system  300 , and will not be described separately, but like numbers will be used to designate like parts. 
     Instead of two top rotating sealing members  366  and  368 , the conveyor system  400  includes a rotary top die or sealing member  466  positioned over the bottom rotary die  460 . The top sealing member  466  can have a plurality of dies or surface configurations  472  with matching profile geometry to the seats  462  of the bottom rotary die  460 , as shown in  FIGS. 19-22 . The dies or surface configurations  472  of the top sealing member  466  can be continuously curved or non-planar to provide an involute shape. In particular, each die  472  has sealing surfaces  473 ,  475 ,  477 , and  479  sized and shaped to match the support surfaces  463 ,  465 ,  467 , and  469 , respectively, of the seats  462  of the bottom die  460 . While the bottom die  460  rotates in the machine direction, the top sealing member  466  rotates in a direction opposite to the bottom die  460  and opposite to the machine direction. 
     When a container  100  received in a seat  462  of the bottom rotary die  460  passes under the top sealing member  466 , the sealing surfaces  473 ,  475 ,  477 , and  479  and the support surfaces  463 ,  465 ,  467 , and  469  of the seat  462  of the bottom rotary die  460  come into contact with the lid material  434  and nip the lid material  434  and the seal flanges  102 ,  104 ,  106 , and  108 , respectively, of the container  100  to hermetically seal the lid material  434  to the container  100 . As shown in  FIGS. 20 and 21 , a rubber or plastic insert  464  may surround the support surfaces  463 ,  465 ,  467 , and  469  of each seat  462  to compensate for variations in material and machine orientations. 
     In particular, as the container  100  seated in the seat  462  of the bottom die  460  passes under the top sealing member  466 , first the lid material  434  and the leading seal flange  102  of the container  100  are nipped between the sealing surface  473  of the top sealing member  466  and the support surface  463  of the seat  462  of the bottom die  460  as shown in  FIG. 20 . As the top sealing member  466  and the bottom die  460  continue to rotate, the sealing surfaces  477  and  479  of the top sealing member  466  roll over the side seal flanges  106  and  108  and nip the lid material  434  to the support surfaces  467  and  469  of the seat  462  of the bottom die  460 . 
     Finally, the sealing surface  475  of the top sealing member  466  and the support surface  465  of the seat  462  of the bottom die  460  nip the lid material  434  and the trailing seal flange  104  to seal the lid material  434  to the container  100  such that the container  100  is hermetically sealed as shown in  FIGS. 21 and 22 . Since the top sealing member  466  applies sealing pressure against the leading, trailing, and side seal flanges  102 ,  104 ,  106 , and  108  of the container  100 , the support surfaces  463 ,  465 ,  467 , and  469  of the seat  462  of the bottom rotary die  460  provide support to and prevent the bending and/or breaking of the seal flanges  102 ,  104 ,  106 , and  108  of the container  100 , respectively, similarly to the support arm  452  at the tacking station  430 . 
     The top sealing member  466  rotates about one axis of rotation and the bottom die  460  rotates about one axis of rotation which can be parallel to, or different from, the axis of rotation of the top sealing member  466 . As such, the sealing member  466  has a constant axis of rotation. Since the support surfaces  467  and  469  of the seat  462  of the bottom die  460  and the side flanges  106  and  108  of the container  100  are non-planar, the sealing surfaces  477  and  479  of the top sealing member  466  have a matching curvature and travel along the respective non-planar sealing flanges  106  and  108  without requiring the top sealing member  466  to travel out of its axis of rotation. It is to be appreciated that the top sealing member  466  and the bottom die  460  can have synchronized speeds of rotation. Further, it will be appreciated that the speed of rotation the sealing member  460  and the bottom die  466  can be synchronized with the speed of the conveyor surface  412 . 
     Thus, unlike the top sealing members  366  and  368 , which can reciprocate by traveling in and out of their axes of rotation, the top sealing member  466  can seal all seal flanges  102 ,  104 ,  106 , and  108  of the container  100  while traveling about only one constant axis of rotation. Similar to the sealing surfaces  366   a ,  368   a , and  638   b  of the top sealing members  366  and  368 , the sealing surfaces  473 ,  475 ,  477 , and  479  of the top sealing member  466  can provide a sealing force that is perpendicular to a line tangential to the non-planar seal flanges  102 ,  104 ,  106 , and  108  of the container  100 . This can provide for a smoothing action that can eliminate undesired wrinkling of the lid material  434  as it is being applied to the container  100  as discussed in more detail above in reference to the conveyor system  300 . 
     With reference to  FIG. 17 , after the top sealing member  466  seals the lid material  434  to the trailing flange  104  of the container  100 , the hermetically sealed container  100  can be transferred from the seat  462  of the bottom rotary die  460  back to the conveyor surface  412  substantially as described above in reference to the conveyor system  300 . For example, the conveyor surface  412  may include a loading platform similar to the platform  317  described above in reference to the conveyor system  300 . Alternatively, the bottom die  460  may simply unload the sealed packages  100  onto the conveyor surface  412  due to its forward rotating motion. Once back on the conveyor surface  412 , the containers  100  can travel along she conveyor surface  412  toward a packing or accumulating station such as known in the art. 
     With reference to  FIGS. 23-28 , a third embodiment of a conveyor system  500  and method for applying a lid to the container  100  will now be described. Similarly to the conveyor systems  300  and  400 , the conveyor system  500  can foe used to seal the container  200  or any other container having one or more non-planar seal flanges. 
     The conveyor system  500  includes a tacking station  530  and a sealing station  570 . As the containers  100  pass through the tacking station  530 , lid material  534  is placed onto the containers  100 , and as she containers  100  pass through the sealing station  570 , the lid material  534  is sealed so the containers  100  to provide a cover and hermetic seal for the food product stored in the containers  100 . 
     The tacking station  530  is identical to the tacking station  330  described with reference to conveyor system  300  and will not be separately described here, but like reference numerals will foe used to designate like parts. Instead of the tacking station  530  shown in  FIG. 23 , the conveyor system  500  may include a tacking station with a pick and place device as described above in reference to the tacking station  330 . 
     The conveyor surface  512  includes a plurality of die seats  562  similar or identical in shape to the die seats  362  and  462  described in reference to conveyor systems  300  and  400  above. The die seats  562  form a so-called die train along the conveyor surface  512 . As the containers  100  exit the tacking station  530  with the lid material  534  tacked to their leading seal flanges  102 , the containers  100  travel along the conveyor surface  512  in the machine direction and are deposited into a respective die seat  562  on the conveyor surface  512  as shown in  FIG. 23 . 
     The container  100  is positioned in the die seats  562  such that only the seal flanges  102 ,  104 ,  106 , and  108  of the container  100  protrude from the cavity formed in the die seat  562 . In particular, the seal flanges  102 ,  104 ,  106  and  108  of the container  100  rest on the support surfaces  563 ,  565 ,  567 , and  569 , respectively, of the die seat  562 . As shown in  FIGS. 25 and 26 , a rubber or plastic insert  564  may surround the support surfaces  563 ,  565 ,  567 , and  569  of each die seat  562  to prevent to compensate for variations in material and machine orientations. 
     The conveyor system  500  includes a rotary top die or sealing member  566  positioned at the sealing station  570  over the conveyor surface  512 . The top sealing member  566  can be identical to the top rotary die or sealing member  466  described above in reference to the conveyor system  400  and where appropriate, like reference numerals will be used to describe like parts. 
     The rotary top sealing member  556  has a matching profile geometry to the seats  562  formed on the conveyor surface  512 , as shown in  FIGS. 26-28 . In particular, the top sealing member  566  has a plurality of dies or surface configurations  572  with die sealing surfaces  573 ,  575 ,  577 , and  579  sized and shaped to match the support surfaces  563 ,  565 ,  567 , and  569 , respectively, of the die seats  562 . The dies or surface configurations  572  of the top sealing member  566  can be continuously curved or non-planar to provide an involute shape. The top sealing member  566  rotates in a direction opposite to the machine direction as shown in  FIG. 23 . When a container  100  received in a die seat  562  passes under the top sealing member  566 , the sealing surfaces  573 ,  575 ,  577 , and  579  and the support surfaces  563 ,  565 ,  567 , and  569  of the seat  562  nip the lid material  534  and the flanges  102 ,  104 ,  106 , and  108 , respectively, of the container  100  to hermetically seal the lid material  534  to the container  100 . 
     In particular, as the container  100  seated in the seat  562  passes under the top sealing member  566 , first the lid material  534  and the leading flange  102  of the container  100  are nipped between the sealing surface  573  of the top sealing member  566  and the support surface  563  of the seat  562  as shown in  FIG. 26 . As the seat  562  moves in the machine direction and the top sealing member  566  rotates, the sealing surfaces  577  and  579  of the top sealing member  566  roll over the side seal flanges  106  and  108  and nip the lid material  534  to the support surfaces  567  and  569  of the seat  562 , respectively. 
     Finally, the sealing surface  575  of the top sealing member  566  and the support surface  565  of the seat  562  nip the lid material  534  and the trailing seal flange  104  to seal the lid material  534  to the container  100  such that the container  100  is hermetically sealed as shown in  FIGS. 27 and 28 . Since the top sealing member  566  applies sealing pressure against the leading, trailing, and side seal flanges  102 ,  104 ,  106 , and  108  of the container  100 , the support surfaces  563 ,  565 ,  567 , and  569  of the seat  562  provide support to and prevent the bending and/or breaking of the seal flanges  102 ,  104 ,  106 , and  108  of the container  100 , respectively, similarly to the support arm  552  at the tacking station  530 . 
     The top sealing member  566  rotates about one axis of rotation which can be parallel to conveyor surface  512 . Since the support surfaces  557  and  569  of the seats  562  and the side flanges  106  and  108  of the container  100  are non-planar, the sealing surfaces  577  and  579  of the top sealing member  566  have a matching non-planar shape and can travel along the respective non-planar sealing flanges  106  and  108  without requiring the top sealing member  566  to travel out of its axis of rotation. It is to be appreciated that the top sealing member  566  can have a synchronized speed of rotation relative to the speed of the conveyor surface  512 . 
     Thus, unlike the top sealing members  366  and  368 , which travel radially in and out of their initial axes of rotation, the top sealing member  566  can seal all seal flanges  102 ,  104 ,  106 , and  108  of the container  100  while traveling about only one axis of rotation. Similar to the sealing surfaces  366   a ,  368   a , and  638   b  of the top sealing members  366  and  368 , the sealing surfaces  573 ,  575 ,  577 , and  579  of the top sealing member  566  can provide a sealing force that is perpendicular to a line tangential to the non-planar seal flanges  102 ,  104 ,  106 , and  108  of the container  100 . This can provide for a smoothing action that can eliminate undesired wrinkling of the lid material  534  as it is being applied to the container  100  as discussed in more detail above in reference to the conveyor system  300 . 
     With reference to  FIG. 17 , after the top sealing member  566  seals the lid material  534  to the trailing seal flange  104  of the container  100 , the hermetically sealed container  100  continues to move in the die seat  562  along the conveyor surface  512  until it reaches an accumulating or packing station. 
     Optionally, any of the methods described in conjunction with the conveyor systems  300 ,  400 , and  500  can include the step of creating a pressure atmosphere in the package that urges the lid in a direction away from the food product stored in the package. Likewise, any of the methods described in conjunction with the conveyor systems  300 ,  400 , and  500  can include the step of creating a protective atmosphere in the food package to increase a shell life of the food product stored in the package. Further it is to be appreciated that the sealing surfaces of the sealing members  366 ,  368 ,  466 , and  566  described in conjunction with the conveyor systems  300 ,  400 , and  500 , respectively, can be made from metal or from a resilient material. 
     These teachings describe containers having non-planar seal flanges. The containers can be sealed using any one of the above-discussed methods geared toward sealing containers having non-planar seal flanges. 
     Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the concept.