Device for cutting a web of material

Abstract

A device for cutting a web of material comprises movement means for moving a web of material to be cut, defining a feed path for the web at least partly rotatable about a central axis and equipped with at least one conveyor mounted around the central axis, at least one cutting head equipped with a laser source and an optical system configured to direct the laser beam towards a cutting zone, where the optical system of the cutting head comprises at least one directing member located inside the conveyor to direct the laser beam away from the central axis towards the cutting zone.

1 . A device for cutting a web of material, comprising:
 movement means by which a web of material to be cut is made to advance and defining for the web a feed path which is at least partly rotatable about a central axis; the movement means comprising at least a conveyor mounted around the central axis and defining an at least partly curved cutting zone;   at least one laser cutting head laser equipped with a laser source configured to generate a laser beam, and an optical system configured to direct the laser beam towards the cutting zone;   Wherein the optical system of the cutting head comprises at least one directing member located inside the conveyor to direct the laser beam away from the central axis towards the cutting zone; the directing member being rotatable about its axis of rotation and oriented in such a way that the laser beam defines on the web a cutting line transversal to the feed path of the web.   
     
     
         2 . The device according to  claim 1 , wherein the conveyor constitutes a curved feed surface for the web and is equipped, at the cutting zone, with at least one permeable portion permeable to the laser beam and facing the directing member, so as to allow the laser beam to pass through the feed surface. 
     
     
         3 . The device according to  claim 2 , wherein the permeable portion is defined by a through opening. 
     
     
         4 . The device according to  claim 2 , wherein the permeable portion is defined by an insert or window which is transparent to the laser beam; the device comprising means for cleaning the insert or window, configured to remove the dirt produced by the sublimation of the fibrous material. 
     
     
         5 . The device according to  claim 1 , wherein it comprises motion transmission means, of mechanical or electro-mechanical type, operatively interposed between the movement means and the directing member to correlate a movement of the movement means along the feed path with the rotation of the directing member about its axis of rotation. 
     
     
         6 . The device according to  claim 1 , wherein the optical system of the cutting head comprises at least one focusing unit operatively located upstream of the directing member and able to move translationally in a straight line between a position close to the directing member, where the focal point of the laser beam is distal from the directing member itself, and a position away from the directing member, where the focal point of the laser beam is proximal to the directing member itself. 
     
     
         7 . The device according to  claim 1 , wherein the directing member is rotatable at least between a first angular, start-of-cutting position and a second angular, end-of-cutting position; the movement means and the axis of rotation of the directing member being positioned in such a way that for each angular position of the directing member, the optical path followed by the laser beam between the directing member and the feed surface for the web is substantially constant in length. 
     
     
         8 . (canceled) 
     
     
         9 . The device according to  claim 7 , wherein the conveyor is defined at least partly by a cylindrical drum rotatable about the central axis having a peripheral surface at least partly defining the cutting zone; the directing member being located at the central axis of the drum and being oriented in such a way that, between the first and the second angular position of the directing member, the laser beam remains in a plane at right angles to the central axis. 
     
     
         10 . The device according to  claim 9 , wherein the movement means are structured to direct the web feed path around the drum along a partly helicoidal line. 
     
     
         11 . The device according to  claim 10 , wherein the drum defines a guide shaped to divert the feed path of the web around the drum itself along a portion of a helicoid extending for approximately 180°. 
     
     
         12 . The device according to  claim 7 , wherein the conveyor comprises a semi-elliptic guide extending at least partly around the central axis and a belt slidable on the semi-elliptic guide; the directing member being rotatable about its axis of rotation which is incident on the central axis at an angle such that for each angular position of the directing member, the laser beam intercepts a point on the semi-elliptic guide located at the same predetermined distance from the directing member itself. 
     
     
         13 . The device according to  claim 12 , wherein the area subtended by the laser beam between the first and the second angular position of the directing member, measured in a plane at right angles to the axis of rotation of the directing member itself, defines a circular sector perimetrically delimited by the semi-elliptic guide. 
     
     
         14 . The device according to  claim 1 , wherein the directing member is rotatable about the central axis. 
     
     
         15 . The device according to  claim 1 , wherein the directing member and the conveyor are rotatable as one about the same axis of rotation corresponding to the central axis.