Opening method for packaging bag with fastener

Abstract

An opening method for a packaging bag with a fastener enables the fastener to be surely opened with a simplified arrangement and by a simple operation as compared to the prior art. A packaging bag with a fastener is held by being gripped at the laterally opposite side edges thereof with a pair of grippers. A pair of suction cups are disposed at respective stand-by positions at both sides of the bag. The suction cups are moved to respective mutually close positions and allowed to adhere to both side surfaces of the bag at respective regions where the fastener is present. The suction cups adhering to the bag are retracted to respective intermediate positions. The movement of the suction cups between the mutually close positions and the intermediate positions is repeated a plurality of times. Thereafter, the suction cups are returned to the stand-by positions. The fastener is opened stepwise.

1 . A method of opening a packaging bag with a fastener that is gripped at laterally opposite side edges thereof with a pair of grippers by using a pair of suction-adhering members disposed at both sides of said packaging bag in such a manner that said suction-adhering members are moved toward each other so as to adhere to both side surfaces of said packaging bag at respective regions where said fastener is present, and said suction-adhering members adhering to said packaging bag are moved away from each other to open said packaging bag, said method comprising: 
 repeating a plurality of times a reciprocating operation including a series of operations of moving said suction-adhering members toward each other, making said suction-adhering members adhere to said packaging bag, and moving said suction-adhering members adhering to said packaging bag away from each other.    
   
   
       2 . The method of  claim 1 , wherein before starting said reciprocating operation, said suction-adhering members are placed at respective stand-by positions apart from each other by a predetermined distance, and when moved away from each other during said reciprocating operation, said suction-adhering members are moved to respective intermediate positions where they are closer to each other than at said stand-by positions, except for a final cycle of said reciprocating operation, which is repeated said plurality of times.  
   
   
       3 . The method of  claim 1 , wherein said reciprocating operation is repeated at least three times.  
   
   
       4 . The method of  claim 2 , wherein said reciprocating operation is repeated at least three times.  
   
   
       5 . The method of  claim 1 , wherein said pair of suction-adhering members are positioned so that respective centers of suction-adhering surfaces of said suction-adhering members are displaced relative to each other in a longitudinal direction of said fastener.  
   
   
       6 . The method of  claim 5 , wherein said suction-adhering members are capable of returnably tilting within a plane perpendicular to the side surfaces of said packaging bag and containing said fastener.  
   
   
       7 . The method of  claim 6 , wherein said suction-adhering members are urged toward respective predetermined positions with predetermined postures by respective resilient members, and when said suction-adhering members have performed said tilting, they are returned by said resilient members.  
   
   
       8 . The method of  claim 1 , wherein said suction-adhering members are disposed so that their respective suction-adhering surfaces face obliquely upward.  
   
   
       9 . The method of  claim 5 , wherein said suction-adhering members are disposed so that their respective suction-adhering surfaces face obliquely upward.