Blade with Side Teeth for Opening/Holding/Closing Pleated Bags and Method for Opening/Closing the Mouth of Bags by Means of Said Blade

Abstract

Blade for opening bags ( 1;2 ) with pleats ( 1 a, 2 a ), comprising a flat body ( 10 ) with a bottom edge ( 11 ) and a top part ( 12 ) suitable for stable engagement with associated operating means, and a tooth ( 20 ) substantially extending in the vertical direction (Z-Z) and connected to the body ( 10 ) along the top edge ( 10 c ) of each lateral side ( 10 b ) of the body ( 10 ), a cavity ( 22 ) which extends in the vertical direction (Z-Z) and is of suitable width in the longitudinal direction (X-X) being formed between each tooth ( 20 ) and the corresponding side ( 10 b ).

1 . Blade for opening/holding/closing bags ( 1 ; 2 ) with pleats ( 1   b,   2   b ), comprising a flat body ( 10 ) with bottom edge ( 11 ) and top part ( 12 ) suitable for stable engagement with operating means (M), characterized in that it is flat and rigid and comprises a tooth ( 20 ; 120 ) substantially extending in the vertical direction (Z-Z) and connected to the body ( 10 ) at the opposite side ends of the top edge ( 10   c ) of the said body ( 10 ) and in that said surface ( 10 ) extends with continuity in the longitudinal direction (X-X) along a section such as to define a cavity ( 22 ) extending in the vertical direction (Z-Z) and of suitable width in the longitudinal direction (X-X) between each tooth ( 20 ; 120 ) and the corresponding side ( 10   b ) of the surface ( 10 ) itself. 
     
     
         2 . Blade according to  claim 1 , characterized in that said tooth ( 20 ; 120 ) has a tip ( 23 ) with a rounded inner edge ( 23   a ). 
     
     
         3 . Blade according to  claim 1 , characterized in that the opposite ends of the bottom edge ( 11 ) have a respective rounded part ( 11   a ) opposite the tooth ( 20 ; 120 ). 
     
     
         4 . Blade according to  claim 1 , characterized in that the outer front surface of each tooth ( 20 ; 120 ) has vertical grooves ( 21 ) designed to form corresponding reliefs ( 21   a ). 
     
     
         5 . Blade according to  claim 4 , characterized in that the surface ( 10   a ) of the body ( 10 ) is set back at a suitable distance (D) from the plane passing through the peaks of the reliefs ( 21   a ) of the tooth ( 20 ; 120 ). 
     
     
         6 . Blade according to  claim 1 , characterized in that said tooth ( 20 ) is formed as one piece with the blade ( 10 ). 
     
     
         7 . Blade according to  claim 1 , characterized in that said tooth ( 120 ) is mounted on the body ( 10 ) of the blade by means of a suitable connecting bracket ( 121 ). 
     
     
         8 . Blade according to  claim 7 , characterized in that said tooth ( 120 ) is shaped in the manner of an “overturned U” with two vertical sections ( 120   a,   120   b ) and a longitudinal section ( 120   c ). 
     
     
         9 . Blade according to  claim 7 , characterized in that said tooth ( 120 ) comprises screw means ( 122 ) able to co-operate with the horizontal section ( 120   c ) of the U so as to form an axis of rotation which is parallel to the vertical direction (Z-Z) and about which the “U” is able to rotate. 
     
     
         10 . Blade according to  claim 1 , characterized in that the perimetral edge of the body ( 10 ) has a chamfer ( 111   a ) on the outside. 
     
     
         11 . Method for opening/holding/closing the mouth ( 1   a;   2   a ) of bags ( 1 ; 2 ) with pleats ( 1   b;   2   b ) by means of blades ( 10 ) and suitable gripping jaws ( 32 ) forming part of a packaging machine (M) and comprising the following steps:
 preparing a pair of blades ( 10 ) each of which is fastened to a respective operating means of the machine (M);   transporting the bag ( 1 ; 2 ) with pleats ( 1   b;   2   b ) so that its mouth ( 1   a;   2   a ) is situated underneath the blades ( 10 );   partially opening the mouth ( 1   a;   2   a ) of the bag;   inserting the blades ( 10 ) in the vertical direction (Z-Z) inside the mouth ( 1   a;   2   a ) of the bag ( 1 ; 2 );   closing in the transverse direction the jaws ( 32 ) of the gripper around the outer surfaces of the mouth of the bag ( 1 ; 2 );   relative opening of the blades ( 10 ) and the jaws ( 32 ) in the transverse direction Y-Y;   filling the bag with the product;   return movement, in the transverse direction Y-Y, of the blades and jaws into the initial closed position of the mouth;   symmetrical closing, in the longitudinal direction (X-X), of opposite flanges ( 31 ) forming part of the machine (M) so that they are inserted inside the respective pleat and interfere with the folding line ( 1   f ) inside the pleat ( 1   b,   2   b ) itself;   
       characterized in that 
       the blade ( 10 ) has teeth ( 20 ; 120 ) according to  claim 1 , said teeth being kept outside the mouth ( 1   a,   2   a ) of the bag and inside the portions ( 1   d ) of the corresponding pleat ( 1   b,   2   b ), and in that 
       closing of the jaws ( 32 ) keeps the portions ( 1   d ) of the pleat ( 1   b;   2   b ) against the respective tooth ( 20 ; 120 ) during all the operations for opening/filling/closing the bag ( 1 ; 2 ). 
     
     
         12 . Method according to  claim 11 , characterized in that said bag ( 2 ) has pleats ( 2   b ) with portions ( 1   d ) formed with a vertical edge ( 2   g ) welded vertically.