Abstract:
An apparatus for manufacturing a circular bag is configured with two anvil half-sections that are movable relative to each other from an open position to a closed position. An ultrasonic sealing tool is provided that is movable towards and away from the anvil half-sections and configured to seal a lid portion to a sleeve portion of the circular bag. In the closed position, the anvil half-sections define an interior space which is at least as large as the exterior circumference of the circular bag to be manufactured.

Description:
BACKGROUND 
       [0001]    This application claims priority to German Patent Application No. 202007010662.9 filed on Jul. 30, 2007 which is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an apparatus for manufacturing a circular bag in which the lid and/or the bottom of a circular bag can be ultrasound welded to a foil sleeve. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is well-known that ultrasound welding shows advantages over thermal bonding, since the welded seal that is generated is clean even when the bag is filled with powdery materials and the powder gets close to the welded seam. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    The present invention provides an apparatus for manufacturing a circular bag that permits easy and reliable ultrasound welding of the lid and/or bottom of the circular bag. In this connection, “circular bag” means that the bag, at least when filled, has a circular, elliptical or another round cross section whereby the shape of the cross section is determined by the shape of the lid and/or bottom. 
         [0005]    In accordance with the invention, an apparatus for manufacturing a circular bag is fitted with two anvil half-sections which are movable relative to each other from an open position to a closed position. In the closed position, the anvil half-sections define an interior space that at least corresponds to the exterior circumference of the circular bag to be manufactured. Furthermore, the apparatus is fitted with an ultrasound sealing tool that is movable towards and away from the anvil half-sections. 
         [0006]    Preferably, a centering device holds the anvil half-sections in a non-movable manner in the closed position. In this manner, the centering device can be fitted with at least one projection and a corresponding slot which are fitted onto or into the walls that are in contact with each other when the anvil half-sections are in the closed position. 
         [0007]    It is preferable in the production sequence that the anvil half-sections are pivotable relative to each other although in other implementations the anvil half-sections are configured such that they can be pushed towards each other within one plane. 
         [0008]    In one embodiment, one of the anvil half-sections is stationary and the other is movable. In this manner, the movable anvil half-section can be pivoted by means of a floating pivoting device on a rotational axis that is located in the border area of the anvil half-sections when in the closed position. 
         [0009]    Preferably, the movable anvil half-section can be locked by a locking mechanism whereby a cross bar locks the movable anvil half-section in the closed position. 
         [0010]    In an alternative implementation, the anvil half-sections are pivotable around a common axis. In this implementation, it is preferable that the anvil half-sections can be moved over a lever chain which reaches its dead point in the closed position. 
         [0011]    In this manner, one of the anvil half-sections can be articulated with an eccentric adjuster that ensures a symmetrical position of the anvil half-sections to a foil sleeve that has to be welded. 
         [0012]    Below, examples of embodiments of the invention will be described in further detail by means of the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    In the following, the invention will be described in greater detail with reference to the attached figures. 
           [0014]      FIG. 1  shows a first implementation of an apparatus for manufacturing a circular bag in the open position according to an embodiment of the present invention. 
           [0015]      FIG. 2  shows the apparatus depicted in  FIG. 1  in the closed position. 
           [0016]      FIG. 3  shows a second implementation of an apparatus for manufacturing a circular bag in the open position according to an embodiment of the present invention. 
           [0017]      FIG. 4  shows the apparatus in  FIG. 3  in the closed position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The implementation of the invention illustrated in  FIGS. 1 and 2  shows a base plate  70  on which a landing  72  is placed. In landing  72  a floating pivoting device  110  is pivotable around an axis  100  that carries one of the anvil half-sections  50 . A second anvil half-section  80  is fitted onto a carrier  74  in a stationary manner. The stationary anvil half-section  80  is fitted with two rounded projections  40  that are configured to fit into correspondingly rounded slots  42  provided in the anvil half-section  50  when the apparatus is closed. The projections  40  and the slots  42  together form a centering device that ensures that the anvil half-sections  50 ,  80  do not move when in the closed position. A frame made from two longitudinal braces  76  and a connecting cross brace  78  is fitted onto the anvil half-section  80  or onto the carrier and forms a mounting for a tommy screw  60 , which acts on a clamping device  120  that is fitted onto anvil half-section  50 . Schematically depicted above the anvil half-sections  50 ,  80 , is an ultrasonic tool  10  configured to weld a bottom or a lid  20  onto a foil sleeve  30 . To achieve this, the foil sleeve  30  is manually placed between the anvil half-sections  50 ,  80  in the open position, as illustrated in  FIG. 1 . The exact height position is precisely predetermined by a vertical height adjustment  90  shown in  FIG. 2 . Subsequently, the apparatus is closed by pivoting movable anvil half-section  50  toward anvil half-section  80  using floating pivoting device  110 , and is held closed using clamping mechanism  120  and the tommy screw  60 . Next, the bottom  20  is placed into the closed anvil half-sections  50 ,  80 . In the anvil half-sections  50 ,  80  there are special centering devices and supply guides configured to pre-form the bottom  10  as it is placed in the foil sleeve. Finally, the ultrasonic tool  10  is lowered so the welding of the bottom  20  to the foil sleeve  30  can occur in the region between the anvil half-sections  50 ,  80 . 
         [0019]    After the welding process is finished, the ultrasonic tool  10  is raised and the tommy screw  60  is loosened so anvil half-section  50  can be pivoted away from anvil half-section  80 . 
         [0020]    A circular bag comprising the foil sleeve  30  fitted with the welded bottom  20  is subsequently removed. If a lid (not shown) is to be welded onto the circular bag, which is now closed at one end by bottom  20 , the circular bag is turned 180° and again placed between the anvil half-sections  50 ,  80 . Finally, the working operations described above are repeated until the lid is welded to the foil sleeve  30 . 
         [0021]    The above-described manufacturing apparatus can be used for manufacturing empty and filled circular bags. The manufacturing apparatus is particularly suitable for manual operation, although the steps described above could be automated. However, a second implementation of an apparatus for manufacturing a circular bag, which is described in connection with  FIGS. 3 and 4 , is particularly advantageous for the automated operation. 
         [0022]    As illustrated in  FIG. 3 , two anvil half-sections  250 ,  280  are disposed within respective receivers  200  within which receivers the position of the respective anvil half-section can be exactly adjusted. The anvil half-sections  250 ,  280  can be pivoted from an open position to a closed position by means of lever chains  130 ,  132 ,  140 ,  142  around an axis  150 . The pivoting movement occurs by means of a servo assembly  180  that activates a crank gear  170 . Integrated into the crank gear  170  is a pneumatic spring  160  that permits reproduction of the clamp force adjustment. The crank gear  170  is articulated to the lever frame  130 ,  132 , which, in turn, is articulated to the receivers  200  for the anvil half-sections  250 ,  280 . Part of the lever frame  130 ,  132  is an eccentric adjuster  130  which is articulated to the crank gear  170 , on the one hand, and to a sealing lever  140  for the anvil half-section  280 , on the other hand. The eccentric adjuster ensures the symmetrical positioning of the anvil half-sections  250 ,  280  with respect to a foil sleeve  30 . 
         [0023]    The lever  132  is articulated to the crank gear  170  and to a sealing lever  142  for the anvil half-section  280 ,  250 . Sideways extruding projections  240  and slots  242  are disposed within the walls of the respective anvil half-sections  280 ,  250 , which touch in the closed position of the device. Projection  240  and slot  242  forms a centering device similar to the one described in connection with the description of the implementation in  FIGS. 1 and 2 . An ultrasound tool  10  is movable in a vertical direction by means of a servo assembly  190  and a crank gear  110  so that, in the closed position of the anvil half-sections  250 ,  280 , ultrasound tool  110  is located just above said anvil half-sections  250 ,  280 . Integrated into the crank gear  110  is a pneumatic spring  120  that facilitates reproduction of the sealing force adjustment. 
         [0024]    As depicted in  FIG. 4 , the closed position of the anvil half-section  250 ,  280  is the dead point of the lever chain  130 ,  132 ,  140 ,  142 , which permits very high clamping force by means of the crank gear  170  without the need for great drive power. 
         [0025]    To seal a foil sleeve  30 , the sleeve is inserted into sealing position by means of a transport system, which is not shown. By means of sorting and supply installation, which is not shown, a lid or bottom  20  is led into the sealing position between the sealing tool and anvil half-sections and is held in position in a gland (not shown). Subsequently, the ultrasound tool  10  is moved in a vertical direction by means of the servo assembly. In this manner, the lid or bottom  20  is pressed into the foil sleeve  30  by the gland in the anvil half-sections  250 ,  280 . Subsequently, sleeve  30  is welded to the lid or bottom. As in the first implementation of an apparatus for manufacturing a circular bag, special centering devices and supply guides are led into the anvil half-sections  250 ,  280  which pre-form the lid or bottom  20  as it is supplied to the foil sleeve  30 . 
         [0026]    In the implementation of an apparatus for manufacturing a circular bag described with respect to  FIGS. 3 and 4 , separate devices are necessary for sealing the lid and the bottom, although it is possible to design a system that turns the foil sleeve  30  by 180°. 
         [0027]    The characteristics of the invention revealed in the above specifications, in the drawings, as well as in the patent claims, could be significant for the realization of the invention individually as well as in any combination.