Speed independent sealing

Abstract

The present invention concerns a method and a device for sealing packages ( 1 ) during continuous movement. A row of packages ( 1 ) is driven by means of a motor ( 8 ) through a sealing station comprising an inductor ( 4 ). The inductor ( 4 ) is driven in a pulse form by means of an IH (induction heating) inductor ( 5 ). A PLC system ( 6 ) is used to control the IH generator ( 5 ). The PLC system ( 6 ) receives information regarding speed and position of the packages ( 1 ) by means of a motor drive ( 9 ) and an encoder ( 7 ), respectively.

1 . A method of sealing packages ( 1 ) during continuous movement, in which a row of packages ( 1 ) is driven by means of a motor ( 8 ) through a sealing station comprising an inductor ( 4 ), characterized in that the inductor ( 4 ) is driven in a pulse form, that the pulses are of a fixed length and that the time between the pulses vary depending on the speed of the row of packages ( 1 ).  
     
     
         2 . The method of  claim 1 , characterized in that a PLC system ( 6 ) is used to control the feeding of the inductor ( 4 ) by means of a IH (induction heating) generator ( 5 ).  
     
     
         3 . The method of  claim 2 , characterized in that information regarding speed and position of the packages ( 1 ) is given to the PLC system ( 6 ).  
     
     
         4 . The method of  claim 3 , characterized in that the information regarding speed and position of the packages ( 1 ) is given by means of a motor drive ( 9 ) and an encoder ( 7 ).  
     
     
         5 . The method of any of the previous claims, characterized in that the applied power is adjusted depending on the speed.  
     
     
         6 . The method of any of the previous claims, characterized in that each package ( 1 ) of the row of packages ( 1 ) has the same length (l p ) in the feeding direction and that the packages ( 1 ) are separated by a distance (l s ) from each other.  
     
     
         7 . The method of  claim 7 , characterized in that the length (l i ) of the inductor ( 4 ) in the feeding direction of the packages ( 1 ) is the same as the length (l p ) of one package plus the length (l s ) of the space between two adjacent packages ( 1 ).  
     
     
         8 . The method of any of the previous claims, characterized in that each package is given a constant sealing energy throughout the length (l p ) of the package ( 1 ).  
     
     
         9 . The method of any of the previous claims, characterized in that the first package ( 1 ) of the row of packages ( 1 ) triggers the sealing system at start-up.  
     
     
         10 . A device for continuous sealing of packages ( 1 ) in a sealing station comprising an inductor ( 4 ), whereby a row of packages ( 1 ) is driven by means of a motor ( 9 ) through the sealing station passing the inductor ( 4 ), consisting of two plates on each side of the row of packages ( 1 ), characterized in that an IH (induction heating) generator ( 5 ) is connected to the inductor ( 4 ) and that the IH generator ( 5 ) is controlled by a PLC system ( 6 ) connected to the IH generator ( 5 ).  
     
     
         11 . The device of  claim 10 , characterized in that the PLC system ( 6 ) is connected to receive information from a motor drive ( 9 ) and an encoder ( 7 ), respectively, connected to the motor ( 8 ).