Centring device for centring a packaging film for a forming unit of a packaging machine

Abstract

A centring device for centring a packaging film for a forming unit of a packaging machine, comprises a support structure connectable to the forming unit; centring elements connected to the support structure and movable between a rest configuration and an active configuration for compressing the packaging film against a guide body of the forming unit; actuation members connected to the centring elements so as to align the packaging film in accordance with a predefined sliding axis thereof. The rest configuration corresponds to a static position whereas the active configuration corresponds to a dynamic position, in which the centring elements are in contact with the film so as to align it with the sliding axis. The centring elements can only be selectively activated under conditions in which the film is skidding with respect to the sliding axis.

1 . A centring device for centring a packaging film for a forming unit of a packaging machine;
 wherein the forming unit comprises a guide body extending along a sliding axis and is configured to receive the packaging film having a substantially tubular and flattened shape, which comes from a reel placed upstream of the forming unit so as to wrap the guide body, and which slides along the sliding axis, so as to form a plurality of packages;   the centring device comprising:   a support structure connectable to the forming unit at an inlet area thereof for the packaging film;   centring elements connected to the support structure and movable between a rest configuration in which the centring elements are proximal to the support structure, and an active configuration in which the centring elements are distal with respect to the support structure for compressing the packaging film against the guide body of the forming unit;   actuation members connected to the centring elements and configured to drive them between the rest configuration and the active configuration;   wherein the actuation members are configured to selectively activate at least one of the centring elements from the rest configuration to the active configuration, and exert a force between the packaging film and the centring elements thereof, so as to align the packaging film in accordance with a predefined sliding axis thereof on the forming unit;   wherein the rest configuration corresponds to a static position in which the centring elements are inactive and disengaged from the film, while the active configuration corresponds to a dynamic working position in which the centring elements are in contact with the film to press it against a surface of the guide body so as to align it with the sliding axis;   and wherein the centring elements are selectively activatable only under conditions of the film skidding with respect to the sliding axis, remaining distal from the film itself during its movement along the sliding axis.   
     
     
         2 . The centring device of  claim 1 , wherein the centring elements are rotatably connected to the support structure and configured to perform an oscillating movement between the rest configuration and the active configuration. 
     
     
         3 . The centring device of  claim 1 , wherein the centring elements comprise a pair of levers which are during use facing each other and arranged astride the sliding axis. 
     
     
         4 . The centring device of  claim 3 , wherein the pair of levers comprises:
 a first lever extending between a first end in which a first idle roller is rotatably mounted and a second end connected to the actuation members; and   a second lever extending between a third end in which a second idle roller is rotatably mounted and a fourth end connected to the actuation members.   
     
     
         5 . The centring device of  claim 4 , wherein the first and second levers are arranged inclined to each other with respect to the sliding axis of the packaging film. 
     
     
         6 . The centring device of  claim 4 , wherein the first and second idle rollers respectively have a rubberised outer surface thereof. 
     
     
         7 . The centring device of  claim 4 , wherein the actuation members comprise a pair of cylinders each connected respectively to the first and second levers. 
     
     
         8 . The centring device of  claim 7 , wherein the pair of cylinders comprises cylinders of the pneumatic type. 
     
     
         9 . The centring device according to  claim 1 , comprising a sensor arranged at the centring device and configured to detect a deviation of the packaging film with respect to the predefined sliding axis. 
     
     
         10 . The centring device of  claim 9 , comprising an electronic control unit connected to the sensor and to the actuation members, and configured to receive a deviation signal from the sensor and send a centring signal to the actuation members to selectively move only one of the centring elements in the active configuration. 
     
     
         11 . A forming unit for an automatic packaging machine, comprising:
 a support frame;   an elongated guide body, connected to the support frame, and extending along a sliding axis of a packaging film;   
       a centring device comprising:
 a support structure connectable to the forming unit at an inlet area thereof for the packaging film; 
 centring elements connected to the support structure and movable between a rest configuration in which the centring elements are proximal to the support structure, and an active configuration in which the centring elements are distal with respect to the support structure for compressing the packaging film against the guide body of the forming unit; 
 actuation members connected to the centring elements and configured to drive them between the rest configuration and the active configuration; 
 wherein the actuation members are configured to selectively activate at least one of the centring elements from the rest configuration to the active configuration, and exert a force between the packaging film and the centring elements thereof, so as to align the packaging film in accordance with a predefined sliding axis thereof on the forming unit; 
 wherein the rest configuration corresponds to a static position in which the centring elements are inactive and disengaged from the film, while the active configuration corresponds to a dynamic working position in which the centring elements are in contact with the film to press it against a surface of the guide body so as to align it with the sliding axis; 
 and wherein the centring elements are selectively activatable only under conditions of the film skidding with respect to the sliding axis, remaining distal from the film itself during its movement along the sliding axis.