Unreeling assembly, particularly for labeling devices

Abstract

An unreeling assembly, particularly for labeling devices, comprising a supporting frame for at least one reel of continuous film which is supported by a respective reel support, which can rotate about an unreeling axis of the reel, and a motorized traction drum, which is designed to unreel the continuous film from the reel of continuous film, between the reel of continuous film and the traction drum there being at least one tensioning element, which is movable, with respect to the supporting frame, along a respective movement path, elements being provided for estimating the radius of the reel of continuous film as a function of the data related to the angular velocity of the reel, to the speed of the film drawn by the traction drum and to the position of the tensioning element with respect to the supporting frame along the respective movement path.

1 - 11 . (canceled) 
     
     
         12 . An unreeling assembly, particularly for labeling devices, comprising a supporting frame for at least one reel of continuous film which is supported by a respective reel support, which can rotate about an unreeling axis of the reel, and a motorized traction drum, which is designed to unreel said continuous film from said reel of continuous film, between the reel of continuous film being unreeled and said traction drum there being at least one element for tensioning said continuous film, said tensioning element being movable, with respect to said supporting frame, along a respective movement path, further comprising means for estimating the radius of said reel of continuous film as a function of the data related to the angular velocity of said reel, to the speed of the film drawn by said traction drum and to the position of said tensioning element with respect to said supporting frame along the respective movement path. 
     
     
         13 . The unreeling assembly according to  claim 12 , wherein said estimation means comprise a “state observer”. 
     
     
         14 . The unreeling assembly according to  claim 13 , wherein said “state observer” is adapted to acquire the data item related to the position of said tensioning element with respect to said supporting frame along the respective movement path from acquisition means which are associated with means for detecting the position of said tensioning element. 
     
     
         15 . The unreeling assembly according to  claim 12 , wherein said reel is supported by a reel support, which is associated with a respective servomotor adapted to actuate rotationally said reel about the respective unreeling axis. 
     
     
         16 . The unreeling assembly according to  claim 13 , wherein said “state observer” is adapted to acquire the data item related to an angular velocity of said reel from control means which are adapted to control a rotation rate of the respective servomotor. 
     
     
         17 . The unreeling assembly according to  claim 13 , wherein said “state observer” is adapted to acquire the data item related to a speed of the film drawn by said traction drum from a control device which is associated with a motor for actuating said traction drum. 
     
     
         18 . The unreeling assembly according to  claim 12 , wherein said estimation means comprise data acquisition means adapted to acquire an angular velocity of the reel of continuous film being unreeled, a speed of the film drawn by said traction cylinder, and a position of said tensioning element with respect to said supporting frame, said acquisition means being adapted to transfer said data to a “state observer” for an estimation of the radius of the reel being unreeled. 
     
     
         19 . The unreeling assembly according to  claim 18 , wherein said “state observer” uses, in order to estimate the radius of said reel being unreeled, the following system of differential equations:
   {circumflex over ({dot over (φ)}= k   1 (ω {circumflex over (r)}−v )− k   2 ({circumflex over (φ)}−φ)
 
     {circumflex over ({dot over (r)}=−k   3   ω−k   1   k   4 ω({circumflex over (φ)}−φ)
 
 where:
 (k 1 , k 2 , k 3 , k 4 ) are constants which depend on the mechanical and electronic characteristics of said unreeling assembly; 
 (v, ω, φ) are the measurements of the speed of said traction drum, of the angular velocity of said reel being unreeled and of the position of said tensioning element; 
 ({circumflex over (φ)}, {circumflex over (r)}) are the estimates of the position of said tensioning element with respect to said supporting frame and of the radius of the reel being unreeled; 
 ({circumflex over ({dot over (φ)}, {circumflex over ({dot over (r)}) are the derivatives of these estimates. 
 
 
     
     
         20 . The unreeling assembly according to  claim 12 , further comprising, between at least two reels and said tensioning element, a joining station adapted to provide a connection between an end portion of the continuous film unreeled from the reel about to be depleted and an end portion of the film supported by the other reel. 
     
     
         21 . The unreeling assembly according to  claim 12 , wherein said tensioning element comprises a tensioning dandy roll, which is supported so that it can rotate by said supporting frame about a respective pivoting axis. 
     
     
         22 . A method for controlling the unreeling, by a motorized traction drum, of a continuous film from a reel, between said reel and said traction drum there being an element for tensioning the continuous film being unreeled, said method comprising a step of estimation, by estimation means, of a radius of the reel of continuous film being unreeled as a function of the data related to an angular velocity of the reel of continuous film being unreeled, to a speed of said continuous film drawn by said traction drum, and to a position of said tensioning element with respect to a supporting frame.