Abstract:
A method and an apparatus for transferring film bags which are supplied in a plurality of parallel rows to a transfer station, to a conveying means which further transports the film bags in a continuous row substantially in a direction transverse to the direction of supply, the film bags to be handed over being preaccelerated in the direction of movement of the conveying means.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method for transferring film bags which are supplied by a supply means in a plurality of parallel rows to a conveying means which further transports the film bags in a continuous row, and to an apparatus for performing the method. 
     BACKGROUND OF THE INVENTION 
     Nowadays, film bags which are used as packing means are mostly treated automatically, for instance filled, closed and further processed. Such film bags consist e.g. of two side films that are sealed to one another at three edges and between the fourth edge of which a bottom film is sealed in that when said bottom film is unfolded room is created in the film bag for the filled product. 
     In such an automated processing line, several film bags are often treated side by side at the same time. For instance, a number of film bags are simultaneously opened in a filling means, further transported by a transportation device, filled at the same time, further transported again and then closed at the same time. 
     However, at other points of the processing line, the film bags must be supplied individually to a processing station. A typical example is e.g. the application of drinking straws to beverage film bags. 
     This creates the problem that the film bags must be transferred by a transportation means which supplies a number of film bags in parallel, to another transportation means from which the film bags are discharged in a single row for further processing. This results in a discontinuous operation because a supplied number, corresponding to the row number supplied in parallel, must always be handed over simultaneously while the conveying means is at a standstill. Moreover, on account of the speeds nowadays used in such processing systems, strong acceleration and deceleration forces are created during transfer, which especially in the case of film bags may easily cause damage. 
     SUMMARY OF THE INVENTION 
     Said object is achieved by a method comprising the features of claim  1  and by an apparatus comprising the features of claim  6 . Advantageous developments are the subject matter of the respective subclaims. 
     According to the method of the invention a respective number of film bags which are simultaneously supplied to a transfer station are received all at once by a transfer device, preaccelerated by said device in the direction of movement of the conveying means, discharged to the conveying means and then transported away by the latter substantially in a direction perpendicular to the direction of supply. The method according to the invention permits a continuous operation. While a number of film bags are being transported by the transfer device to the conveying means and handed over to the latter, a further number of film bags are supplied by the supply means to the transfer station. On the other hand, the conveying means continues its travel, transporting away already transferred film bags for further processing while the transfer device takes over a new number of film bags from the supply means and transports the bags to the conveying means. With a corresponding setting of the relative speed between the supply means and the conveying means a continuous operation is thereby ensured. Moreover, the preacceleration of the received film bags in the conveying direction has the effect that the acceleration forces are reduced upon discharge to the conveying means. Thus, damage upon discharge to the conveying means is prevented. Small acceleration forces during discharge also enhance the accuracy of the positioning operation for the bags on the conveying means 
     The method according to the invention is particularly efficient when the speeds of the conveying means and of the transfer device are matched such that the conveying means transports away a number of film bags which have simultaneously been handed over, within the same period in which the transfer device has received a further identical number of film bags and transported and preaccelerated the same for discharge to the conveying means. It is thereby ensured that the capacity of the conveying means is exploited in an optimum way because no irregular distances on the discharge device can be created between the individual film bags. Moreover, this facilitates the further processing in automated processing stations. 
     Advantageously, in the method of the invention the relative speed between the conveying means and the film bags at the moment of discharge to the conveying means may be zero or almost zero. Thus, acceleration forces acting on the film bags are entirely avoided during discharge, whereby the risk of damage to the film bags is further reduced and the accuracy of the bag positioning operation is increased. 
     The film bags are simply transported away by the conveying means in a slightly inclined position. Such an inclined position permits an easy discharge operation because the film bags are held on the discharge device on account of their inclined position. 
     The film bags can directly be deposited on the conveying means by the transfer device However, it is easier when the film bags are lifted from the supply means, transported via the conveying means and released at said place. The demands made on a precise discharging operation are thereby reduced. 
     For performing the method of the invention, the apparatus according to the invention comprises a supply means which supplies film bags in parallel rows, a conveying means which transports away the film bags in a continuous row substantially in a direction perpendicular to the supply direction, and a transfer device which takes over from the supply means a respective number of film bags corresponding to the number of supplied rows, preaccelerates said bags in the direction of movement of the conveying means and discharges the same to the conveying means. 
     The transfer device can perform the individual movements e.g. in the manner of a robot controlled by a microprocessor. A particularly simple configuration is however a transfer device which comprises a carrier, a transverse bar parallel thereto with carrier means for the film bags and at least one lever arm which interconnects the transverse bar and the carrier, the connections being designed such that the angle enclosed by the lever arm with the carrier or transverse bar is variable. Such an arrangement permits a preacceleration of the received film bags in an easy way by varying the angle. 
     Such a construction is particularly stable if at least two lever arms are provided so that the carrier, the lever arms and the transverse bar form a parallelogram of a variable angle. 
     The angle can be varied in various ways. One simple possibility consists in pivoting a lever arm with the help of a motor. Said motor can be controlled such that upon discharge of the film bags the transverse bar and the conveying means have a relative speed of zero or almost zero. Acceleration forces can thus not act on the film bags during the discharge operation, which reduces the risk of damage. Advantageously, the movement of the transverse bar in the area of the conveying means is so high that it is slightly higher than a film bag positioned on the conveying means. It is thereby avoided that the movement of the transverse bar might impede the transportation of the film bags. Moreover, it is thereby easily possible to release the film bags to the conveying means, which represents a simple possibility of discharge. 
     To this end the transverse bar can perform a lifting movement during the transfer operation. To this end a linkage guide is just provided that effects the lifting movement during change in the angle between the at least one lever arm and the carrier. Such a linkage guide represents a possible configuration that is simple, mechanical and inexpensive. The lift can also be carried out pneumatically or by a motor. 
     The carrier means may comprise clamps on the transverse bar that are capable of gripping the film bags at the upper end thereof. The supply means may be an endless belt on which a number of film bags are conveyed in parallel. 
     Receiving cases in which the film bags are supplied may be arranged on the endless belt. The supply means may consist of chains extending in parallel and including receiving cases mounted thereon, in which the film bags are supplied. 
     The discharge means may e.g. comprise a transportation belt. Advantageously, holding means are provided on such a transportation belt, the film bags being transported in said means. Such holding means ensure a safe transportation. Such a safe transportation can be realized in a particularly easy manner when the holding means are designed such that the film bags are transported in a slightly inclined position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     It may here be that the film bags are directly transported away side by side. In an advantageous embodiment, however, the holding means comprise side guides for the film bags that ensure a regular arrangement of the film bags on the transportation belt in an easy way. 
     An embodiment of the apparatus of the invention and the method of the invention shall now be explained in more detail with reference to the enclosed figures, in which: 
     FIG. 1 a  is a schematic top view on a transfer station at the moment when the film bags are received; 
     FIG. 1 b  is a schematic top view on a transfer station in an intermediate state; 
     FIG. 1 c  is a schematic top view on a transfer station at the moment when the film bags are discharged; and 
     FIG. 2 is a lateral schematic view for illustrating the whole transfer operation. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 a  to  1   c  show the transfer region. Such a transfer region is e.g. found in a beverage filling system. Beverage film bags  2  which have been filled and closed are discharged with the help of the transfer device to a conveying means which conveys the beverage film bags e.g. to a drinking-straw applying station. 
     Filled and closed beverage film bags  1   a  are supplied by a supply means  2  in supply direction  4   
       13  designates a carrier which at pivotal points  14  and  16  has hinged thereto pivotable lever arms  12   a ,  12   b . A motor  18  is provided for the pivotal movement in the direction of arrow  20 .  11  designates a transverse bar having a bottom side provided with clamp means, which are not explicitly shown in FIG. 1 a  to  c . Film bags  1   b  which are taken over by the transverse bar  11  are shown in broken line in FIG.  1 . The transverse bar  11 , the two lever arms  12   a ,  12   b  and the carrier  13  form a parallelogram of a variable angle γ. 
       6  designates a conveying means which moves in direction of arrow  10 . Holding means  8  are positioned on said conveying means  6 .  1   e  designates beverage film bags which are already conveyed. 
     FIG. 1 b  shows the same transfer station at a later time at which angle γ between the lever arms and the carrier is enlarged.  1   c  designates film bags which are transported in suspended fashion by the transverse bar  11   
     FIG. 1 c , in turn, shows the same transfer station at the time when the film bags  1   d  are discharged from the transverse bar  11  to the conveying means  6 . 
     FIG. 2 is a lateral schematic drawing of the same transfer station. A clamp mechanism  26  with clamps  28  is provided on the transverse bar  11 . Arrow  24  designates the return direction of the emptied receiving cases  30  in which the film bags  1   a  have been supplied. 
     Arrow  22  shows the lifting movement of the transverse bar  11  which, as will still be described, is initiated during the pivotal operation of the lever arms  12   a ,  12   b.    
     The right upper half of FIG. 2 illustrates a state of the transfer station at a later time, in which after the lifting movement  22  the clamps  28  are opened above the holding means  8  of the conveying transportation belt  6 .  9  designates lateral guides of said holding means  8 . This illustration shows that the bottom surface  8  of the holding means is inclined and the holding means only comprise one rear wall. The continuous line shows a film bag shortly after the clamps  28  have been opened. A film bag which a moment later rests on the rear wall of the holding means is shown in broken line. 
     The method according to the invention shall now be explained with reference to the mode of operation of the apparatus according to the invention by way of an exemplary transfer device in a machine for filling beverage film bags. 
     The beverage film bags are supplied by the supply means  2  in parallel rows. Any desired number of parallel rows is here possible. The beverage film bags  1   a  are transported in receiving cases  30  which are fastened to the supply means  2 . 
     As shown in the left half of FIG.  2  and in FIG. 1 a , respectively, clamps  28  engage the beverage film bags  1   b  in the transfer region. As soon as the clamps  28  have been closed, the motor  18  starts to move the lever arm  12   a  in direction  20 . This creates a state as shown in FIG. 1 b.    
     While the beverage film bags  1   c  are transported away from the supply means  2  with the help of the transverse bar  11  and the clamps  28 , the supply device  2  moves on continuously to move a further number of beverage film bags into the transfer region. While the beverage film bags  1   c  are transported away, a lifting movement of the transverse bar  11  is initiated. To this end a linkage guide is e.g. provided which for reasons of clarity is not explicitly shown in the figures; a motor type drive or a pneumatic drive serves as an alternative. A simple configuration is e.g. a ramp against which the lever arms  12   a  and  12   b , respectively, abut while being pivoted by the motor  18 . 
     The lever arms  12  and  12   b  are pivoted along the arc represented by arrow  20  continuously up to the state shown in FIG. 1 c . The speed of the pivotal movement is here chosen such that at the time shown in FIG. 1 c  the transverse bar  11  has the same speed in conveying direction  10  as the transportation belt  6 . 
     In this state the clamps  28  are e.g. opened by a control means and the film bags  1   d  fall into the holding means  8  positioned thereunder. In this process they are aligned by the side guides  9  in their lateral position. As shown in FIG. 2, the holding means  8  are equipped with a slightly inclined bottom surface so that the film bags come to rest in an inclined way. Since the transportation belt  6  is continuously moved with the holding means  8 , the film bags  1   e  are continuously conveyed after ejection. The relative speed of the film bags  1   d  and of the transportation belt  6  in the discharge process is zero or almost zero, so that acceleration forces that might damage the film bags are not acting on the film bags. 
     Upon release the pivotal movement of the lever arms  12   a  and  12   b  is continued, as shown by arrow  20  in FIGS. 1 a  to  1   c . Finally, the pivotal movement of the lever arms  12   a  and  12   b  is reversed and the transverse bar is again returned along the same path which is illustrated in FIGS. 1 a  to  1   c  and has been described above. 
     The linkage guide is traveled through in reverse direction. Alternatively, it is also possible to use a motor type drive or a pneumatic drive. Since the lifting movement  22  has lifted the transverse bar to a height sufficiently above the transportation belt  6 , it is ensured that the clamps  28  during the return movement of the transverse bar  11  will not collide with the already deposited film bags  1   e.    
     The pivotal return movement is continued until the state shown in FIG. 1 a  is reached again, and the transfer operation is repeated with the next number of film bags While the transverse bar  11  is further pivoted or pivoted back after the discharge operation shown in FIG. 1 c , and while a new number of film bags  1   b  are taken over on the transverse bar with the clamps  28  and moved to the transportation belt  6 , said belt is continuously moving on. With a suitably timed coordination, the transportation belt  6  is thus advanced further exactly by such a distance that the film bags  1   d  can be ejected onto the transportation belt  6  directly in accordance with the previously discharged number of film bags. 
     Thus the above-described apparatus and the associated method make it possible that two continuously conveying transportation belts can be used and that a transfer is possible although on the one transportation belt quite a number of film bags are simultaneously conveyed to the transfer station while the other conveying means discharges a single continuous row. Such a continuous supply and discharge facilitates the integration of such a transfer device into an automated processing system. Thanks to the preacceleration of the film bags to the speed of the conveying transportation belt, the risk of damage to the film bags is reduced in addition to an acceleration of the whole process.