Patent Publication Number: US-6217497-B1

Title: Stand-up apparatus for producing flexible pouches

Description:
This application claims the benefit of U.S. Provisional Application No. 60/107,626, filed Nov. 9, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The invention relates to an apparatus for producing flexible stand-up pouches and, in particular, an apparatus for punching holes in a web during production of the pouch. 
     II. Description of the Prior Art 
     It is well known to produce flexible pouches from a continuous web of plastic film. The web is preprinted with the label and product information. A registration eyemark is formed along one edge of the web for each preprinted panel. The web is fed to a knife cutter. A sensor such as an electronic eve is used to detect the registration mark and generate a signal to stop the web and initiate the knife cutter to cut a panel from the web. Fitments are then attached to the panel and the pouch is formed by sealing the edges. 
     When a stand-up style pouch is being produced, a pair of holes are punched in the web in order to facilitate forming the welding of the base of the stand-up pouch. These holes permit welding of the corners of the leading and trailing edges of the pouch to the base to form gussets on the sides. The holes are punched in the web by a die cutter before the web moves to the knife cutter to form the panels. The die cutter is positioned upstream of the knife cutter and is activated to punch the holes when the web is stopped downstream at the cutting station. 
     However, the length between the registration marks on the web or pitch is not always equal due to shrinkage or stretch during the printing of the web. The length of each pitch or panel can vary as much as +/−0.0625 inches per pouch. The result of this variability in length can cause a variety of hole punching problems when the holes are punched upstream of the cutoff knife. As an example, if the stand-up hole punches are 20 pitches upstream of the cutoff knife and the variability of the web is +/−0.0625 inches, the hole punch could be theoretically +/−(20)*0.0625 inches or +/−1.25 inches off. The position of the hole punch must be manually adjusted whenever the web material has a length variation, a splice, or if there is a roll change. This results in a great slow down in the process. 
     Accordingly, it would be advantageous to automatically adjust the position of the die cutter to punch the holes in the proper position. 
     SUMMARY OF THE PRESENT INVENTION 
     The present system compensates for variations in the web length and automatically positions the web for punching stand up holes. The system utilizes a secondary or die punch registration eye. The die punch eye is positioned a distance of one pitch or panel width upstream of the stand-up hole punch. When the eyemark is detected, a servo powered secondary or die punch feed drive immediately stops the web. The web is thus aligned in exactly the correct position for proper hole punch alignment. 
     A dancer system is positioned downstream of the die punch feed drive. After the die punch punches the holes, the die punch feed drive is activated to move the web into the die punch dancer system. The dancer system accumulates the web and maintains a constant tension on the web until it is moved downstream by the primary web drive. 
     The present invention permits the punch system to operate independently from the main web feed roll system without running any risk of either breaking the web because of too much tension or having too much slack in the system thus causing operating problems. 
     This system precisely punches the stand-up holes in the proper location regardless of variability in the printing of the web, a splice, or when a new roll is put through the machine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The apparatus and features of the invention depicted in the accompanying drawing which form a portion of the disclosure and wherein like reference numerals are used for like elements and wherein: 
     FIG. 1 is a perspective view of a stand-up pouch formed in accordance with the invention. 
     FIG. 2 is a perspective view partly broken away showing a die punch apparatus for use in forming flexible stand-up pouches in accordance with the invention, and 
     FIG. 3 is a schematic of a pouch forming machine with punching apparatus in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     An automatic punching apparatus  10  for use in producing a stand-up flexible pouch in accordance with the invention is shown in FIG.  2 . The apparatus  10  is used for forming a stand-up flexible pouch  12  of the type shown in FIG.  1 . The pouch has side gussets  14  formed when comers  16  of the pouch are folded inwardly and heat welded to a bottom panel. The welding process is improved by cutting a pair of access holes  18  through the bottom panel. The holes  18  permit the heat from a heat sealer (not shown) to pass through the holes to reach the folded corners  16  for welding. 
     The punching apparatus  10  is suitable for use on virtually any type of pouch making machine, such as the horizontal form, fill and seal machine  20  by Laudenberg of Whipplefurth, Germany, and shown in FIG.  3 . The machine  20  is of a type which produces flexible bags or pouches  12  in a continuous operation from a web  22  of plastic film. The web is fed through the machine by a primary drive unit  24  from a spool  26  which has been preprinted in panels. A registration eyemark  28  is positioned along one edge of the web  22  of each panel. The separation between eyemarks  28  is one pitch “p”, which is equivalent to the panel length. The registration mark  28  is placed to indicate the cut line which separates the top of one panel from the bottom of another panel. The machine  20  has a cutting station with an electronic eye  30  positioned to detect the position of the registration eyemark  28  and activate a knife cutter  32  to separate a panel from the web  22 . 
     The punching apparatus  10  in accordance with the invention is shown in FIGS. 2 and 3. The punching apparatus includes a punch eyemark sensor  34 , a hole punch  36 , a servo powered secondary or punch drive  38 , and a secondary or punch dancer system  40 . The punching apparatus  10  is positioned upstream of the knife cutter  32  and downstream of the spool  26  from which the web  22  is unwound. The web  22  is delivered to the apparatus over a roller  42  and passes sequentially beneath the eyemark sensor  34  and punch mechanism  36  to the servo powered punch feed drive  38 . The registration sensor  34  may be of any suitable type and is positioned to read the registration mark  28  upstream of the punch mechanism  36 . The punch mechanism  36  may include a positioning mechanism  44  and a die cutter  46 . The positioning mechanism  44  adjusts the position of the die cutler  46  along the web with respect to the eyemark sensor  34 . The positioning mechanism  44  may be of any suitable type, such as a servo controlled feed screw. In the preferred embodiment, the die cutter  46  is positioned to be a distance one pitch “p” downstream of the registration eye  34 . The punch feed drive is servo powered to precisely position the web and operates independently of the main feed drive  24 . 
     The punch dancer system  40  is positioned downstream of the punch feed drive  38  to receive the web  22  from the feed drive  38  once the punch has been completed and the feed drive  38  is reactivated. The dancer system  40  permits the main feed drive to run independently of the punching operation and to take the web  22  from the dancer system  40  when the punch feed drive  38  is stopped for the punching operation. The dancer system  40  is conventional and includes three rollers  50  which are supported in position and two vertically movable rollers  52 . The movable rollers  52  are guided to move downwardly to place tension on the web  22  which is fed into the dancer system  40 . When the main feed drive  24  is activated, the web  22  is pulled from the dancer system  40  and the movable rollers  52  are permitted to move upwardly, keeping tension on the web  22  at all times but permitting the web to be drawn to the cutting station. 
     OPERATION 
     The registration sensor  34 , punch mechanism  36 , and punch feed drive  38  are connected to a controller  54  or a CPU. The distance between the die cutter  46  and registration sensor  34  is set to be equal to the pitch. The positioning mechanism  44  is used to position the die cutter. After the position is determined, the die cutter  46  remains in the same position with respect to the eyemark sensor  34  and is only changed for making packages having a different panel size. When the eyemark sensor  34  detects a registration mark  28 , it sends a signal to a controller  54  which immediately sends a signal to stop the punch feed drive  38 , stopping the web  22  beneath the die cutter. The controller  54  then activates the die cutter  46  to punch the holes  18 . After the hole cutting is complete, the feed drive  38  is activated to move the web  22  to the dancer  40  and repeat the cycle. The punched web is moved by the primary feed drive  24  to the cutting station. 
     It is understood that while certain embodiments of the present invention have been illustrated and described, it is not limited to specific forms of arrangements herein described and shown.