Method and apparatus for automatically joining reels of web material

Abstract

The apparatus for automatically joining reels of web material includes a joining assembly adapted to take the trailing edge of a first expiring reel of web material and to apply it on the leading edge of a second reel of web material. Said leading edge is held close to said second reel of web material by gripping means rotated, at the same angular speed, by the same second reel. Said leading edge bears, on the side facing outwardly, a label of adhesive material.

1 . A method for automatically joining reels of web material, comprising the steps of:
 a. arranging in a working position, placed side by side of the working position of a first unwinding reel of web material to feed in line the same web material, a second reel of web material, said first and said second reel being rotatable with parallel axes of rotation;   b. associating a leading edge of said second reel of web material with gripping means operated in rotation by the same second reel of web material, said leading edge bearing adhesive means on the side facing outwardly;   c. detecting by sensor means the residual diameter of said first unwinding reel of web material;   d. rotating said second reel of web material, when detecting a predetermined residual diameter of said first unwinding reel of web material;   e. cutting a trailing edge of said first unwinding reel of web material;   f. engaging said trailing edge of said first reel of web material with a joining assembly arranged downstream of said first reel according to the feed direction of said web material;   g. applying said trailing edge of said first reel of web material on said leading edge of said second reel of web material rotated by said gripping means integrally with the same second reel of web material; and   h. joining said trailing end and said leading edge of the reels of web material by means of said adhesive means associated with the same leading edge of said second reel.   
     
     
         2 . An apparatus for automatically joining reels of web material comprising a joining assembly adapted to take the trailing edge of a first reel of web material that is about to expire and to apply it to the leading edge of a second reel of web material, said leading edge being held close to said second reel of web material by gripping means rotated, at the same angular speed, by the same second reel and bearing a label of adhesive material on the side facing outwardly. 
     
     
         3 . The apparatus of  claim 2 , wherein said gripping means comprises a radial arm provided at a free end with a vane connectable to suction means to put under vacuum its surface facing outwardly, said radial arm being mounted in axis to said reel and rotated thereby at the same angular speed. 
     
     
         4 . The apparatus of  claim 2 , wherein said joining assembly comprises a plurality of rollers rotatable, in a suitable phase relationship, according to respective axes of rotation parallel to the axis of rotation of said reels, to grip in sequence said web material unwinding from said first reel, to cut said trailing edge of the same first reel, to transfer said trailing edge of the first reel onto said leading edge of the second reel and to join through said label of adhesive material said trailing end to said leading edge. 
     
     
         5 . The apparatus of  claim 2 , wherein said joining assembly comprises a first roller for gripping and unwinding the web material said first roller being connectable to drawing means to put under vacuum its peripheral surface, so as to retain said web material unwinding from the first reel. 
     
     
         6 . The apparatus of  claim 5 , wherein said joining assembly comprises, downstream of said first roller, according to the direction of travel of said web material, a second roller for transferring said trailing edge of the first reel onto said leading edge of the econd reel, means for cutting the web material unwinding from said first reel, suitable for separating said trailing edge, being carried on said second roller. 
     
     
         7 . The apparatus of  claim 6 , wherein said cutting means comprises a blade housed inside a seat made radially in the body of said second roller said blade being operable between an inactive retracted position and an advanced position, protruding from said second roller to cut said web material. 
     
     
         8 . The apparatus of  claim 7 , wherein said joining assembly comprises, downstream of said second roller a third roller for driving the web material to be fed, once said leading edge of the second reel is joined to said trailing end of the first reel, said third roller being connectable to drawing means to put under vacuum its peripheral surface. 
     
     
         9 . The apparatus of  claim 4 , wherein said joining assembly is held by a movable assembly adapted to translate the same joining assembly in an axial direction to said rollers for a stroke, whose width is greater than the thickness of the web material 
     
     
         10 . The apparatus of  claim 4 , wherein said joining assembly is carried by a movable assembly adapted to rotate the same joining assembly according to a vertical axis between a first and a second working positions, which are specular to each other.