Abstract:
A form-fill-seal web packaging system includes a pressure monitor at the sealing station monitoring sealing pressure. A bladderless actuator effects relative movement of dies and applies sealing pressure.

Description:
BACKGROUND AND SUMMARY 
     The invention relates to form-fill-seal web packaging systems. A form-fill-seal web packaging system packages a product. One type of packaged product is a food product, e.g. hotdogs, and other packaged food items. Other types of packaged products include non-food products. For example, there is a growing demand for one-time use disposable sterile medical products and devices. For packaging of these types of products, ultra high quality validate able sealing is critically important to maintain sterility while also allowing for easy peel access to the contents of the package. Such products may typically include disposable syringes, needles, baby bottles for premature infants, IV (intravenous) devices, surgical prep kits, sterile gloves, and so on. 
     A web transport conveyor transports the lower web from upstream to downstream through a series of stations which form the lower web into a component of a package, e.g. a pocket or downwardly depending cavity, at a forming station, and receive the product at a loading station into the lower web package, and close and seal the package with the upper web at a closing and sealing station, typically thermally adhesively sealing the upper and lower webs to each other. A pasteurization station may be provided between the loading station and the closing station for pasteurizing and/or sterilizing the product. 
     The present invention arose during continuing development efforts directed toward the above noted form-fill-seal web packaging systems, including improvements at the sealing station. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a form-fill-seal web packaging system. 
         FIG. 2  is an enlarged isometric view of a portion of the system of  FIG. 1  incorporating the present invention at the sealing station. 
         FIG. 3  is an isometric view of a portion of  FIG. 2 , with a section line taken along line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 2 . 
         FIG. 5  is like  FIG. 4  and shows a further operational position. 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 2 . 
         FIG. 7  is an enlarged view of a portion of  FIG. 3 . 
         FIG. 8  is an enlarged view of a portion of  FIG. 4  taken along line  8 - 8 . 
         FIG. 9  is an enlarged view of a portion of  FIG. 5  taken along line  9 - 9 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows form-fill-seal web packaging apparatus  10 , and is taken from, and uses like reference numerals from, U.S. Pat. Nos. 6,843,043 and 5,170,611, both incorporated herein by reference. As noted in the &#39;043 and &#39;611 patents, packaging apparatus  10  generally includes a lower web supply station  12  for supplying a lower web  14  of flexible packaging material from a supply roll  16 , a forming station  18 , a loading station  20 , an upper web supply station  22  for supplying an upper web of flexible packaging material  25 , and a downstream station  26  closing and sealing the package by thermally adhesively sealing the upper and lower webs at pre-applied adhesive therebetween by moving at least one of upper and lower dies towards the other to respectively engage the upper and lower webs therebetween and apply heat and pressure to adhesively seal the upper and lower webs to each other, as is known. As described in the &#39;043 and &#39;611 patents, the web transport conveyor provided by apparatus  10  transports lower web  14  through the noted series of stations which form the lower web into a component of a package, e.g. a downwardly depending pocket or cavity, at forming station  18 , and receive a product P at loading station  20 , and close and seal the package with the upper web  25  at closing and sealing station  26 . The webs are advanced by the indexing apparatus disclosed in the &#39;611 patent, as controlled by the control modules  250  and  278 , also as set forth in the &#39;611 patent, to which further reference may be had. The conveyor advances from upstream to downstream, wherein closing and sealing station  26  is downstream of loading station  20 , and loading station  20  is downstream of forming station  18 . As disclosed in the &#39;043 patent, a pasteurization station  300  may be provided between loading station  20  and closing and sealing station  26 , for pasteurizing product P in product cavity pocket  302  in lower web  14 . 
       FIGS. 2-9  show a sealing machine  400  for closing station  26  for thermally adhesively sealing upper and lower webs  25  and  14  of a package at sealing station  26 . The sealing machine includes upper and lower dies  402  and  404 , at least one of which is movable relative to the other such that the dies are relatively movable toward and away from each other as shown at arrows  406  and  408 ,  FIGS. 9 and 8 , respectively, to respectively engage and release upper and lower webs  25  and  14  therebetween and apply heat and pressure to thermally adhesively seal the upper and lower webs to each other. Sealant  409  is pre-applied to the upper web and/or lower web, as is standard. Also as is standard, the upper die includes one or more heater cartridges  410 ,  FIG. 5 , e.g. electrical resistance heaters, applying heat to activate the sealant to thermally adhesively seal the upper and lower webs to each other, which is preferred in the present system. It is typical and known in the prior art to monitor the control the parameters of temperature and time during the sealing operation to create a seal between the upper and lower webs using a thermally activated sealant. The present system, in one aspect, provides a pressure monitor, to be described, to additionally monitor sealing pressure. 
     An actuator  410 ,  FIG. 2 , actuates the upper die  402  to move toward the lower die  404 ,  FIGS. 5 ,  9 . The pressure monitor is preferably provided by one or more sensors  412 ,  414 ,  FIGS. 2 ,  3 ,  6 , sensing the force applied by the actuator to the upper die. The one or more sensors  412 ,  414  are preferably provided by load cells through which the force is applied from the actuator to the upper die. Upper die  402  is provided by a pair of parallel horizontal plates  416  and  418 ,  FIG. 3 , spaced by load cells  412  and  414  therebetween,  FIG. 6 . Plate  416  is engaged by the actuator, to be described, to transfer force through load cells  412 ,  414  to plate  418  to apply sealing pressure to the webs,  FIGS. 5 ,  7 - 9 . Plate  418  is heated by heater cartridges  410  to apply heat to thermally adhesively seal the upper and lower webs to each other. Load cells  412  and  414  are laterally spaced from each other for sensing even distribution of sealing pressure across the plates for uniform sealing of the webs, and for sensing differential sealing pressure across the plates to detect nonparallel skewing of the plates relative to each other to in turn detect an obstruction at the webs. 
     The actuator  410  is provided by a plurality of laterally spaced cams such as  420 ,  422 ,  FIGS. 2-6 , on a respective plurality of laterally spaced shafts such as  424 ,  426  driven by a motor  428 , preferably a servomotor, having an output shaft  430  driving via belt  432  the shaft  424  which in turn drives via belt  434  and idler tensioner pulley  436  the shaft  426 . Shafts  424  and  426  are each rotatable to a first shaft position,  FIG. 5 , actuating the upper die to a sealing position to apply sealing pressure to the webs, and rotatable to a second shaft position,  FIG. 4 , to release the sealing pressure. Eccentric cams  420  and  422  engage plate  416  to apply force through respective load cells  412  and  414  to plate  418  to apply the noted sealing pressure. One or more return springs  438  and  440 ,  FIGS. 3-5 , bear against plate  416 , such that the cams  420  and  422  engaging plate  416  must overcome the bias of the return springs  438  and  440  to apply force through the load cells  412  and  414  in a first direction  406  to plate  418 . Return springs  438  and  440  bias plate  416  in a second direction  408  opposite to first direction  406 , to bias the upper die away from the sealing position such that the upper die moves to a non-sealing position when shafts  424  and  426  rotate to the noted second shaft position. The lower ends of springs  438 ,  440  bear against a carriage  442  supporting the upper die, which carriage may be lowered downwardly to engage lower die box  404  at the outer peripheral edge of lower web  14 , or which may remain stationary while lower die box  404  is raised upwardly for example as in FIGS. 2-5 of the &#39;611 patent. 
     Motor  428  is preferably a servomotor to drive each of shafts  424  and  426  in a first rotation direction, e.g. clockwise as shown at arrows  444  in  FIG. 4 , from the noted first shaft position (sealing) to the noted second shaft position (non-sealing), and in a second opposite rotation direction, e.g. counterclockwise as shown at arrows  446  in  FIG. 5 , from the noted second shaft position (non-sealing) to the noted first shaft position (sealing). Shaft  424  thus is driven to rotate in opposite rotation directions, namely in a first rotation direction  444  from the noted first shaft position to the noted second shaft position, and in a second opposite rotation direction  446  from the noted second shaft position to the noted first shaft position. Shaft  426  likewise is driven to rotate in opposite rotation directions, namely in the first rotation direction  444  from the noted first shaft position to the noted second shaft position, and in the second opposite rotation direction  446  from the noted second shaft position to the noted first shaft position. These opposite rotation directions of the shafts avoid the necessity of reaching a full bottom-dead-center engagement of cams  420 ,  422  and plate  416 , which would require closer tolerance. That is, if shafts  424  and  426  only rotated in a single direction, the cams must pass through bottom-dead-center. Instead, motor  428  is preferably provided by a reversible servomotor to effect opposite rotation directions of the shafts, and avoid the necessity of reaching a full bottom-dead-center engagement of the cams and the upper die. 
     The described preferred actuator arrangement provides a bladderless actuator  410  actuating the upper die to move toward the lower die. Laterally spaced cams are preferably provided at  420  and  422  and are also preferably provided at the other ends  448  and  450  of shafts  424  and  426  and apply sealing pressure along first force direction  406  through laterally spaced load cells such as  412 ,  414  and such other load cells as may be desired, for example proximate the other ends  448  and  450  of the shafts, which laterally spaced load cells sense even distribution of sealing pressure across plates  416 ,  418  for uniform sealing of the webs, and sense differential sealing pressure across the plates to detect nonparallel skewing of the plates relative to each other to in turn detect an obstruction at the webs. 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different configurations, systems, and method steps described herein may be used alone or in combination with other configurations, systems and method steps. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims.