Wrapping machine and wrapping method

Abstract

A wrapping machine (1) for wrapping a load (100) with a film (50) comprises a main frame (2) that slidably supports a supporting carriage (3), a moving ring (4) rotatable and supporting an unwinding unit (5) provided with a reel (51) of film, pre-stretching rollers (52, 53) and at least one electric motor (37, 38) to rotate said pre-stretching rollers (52, 53), sliding electric contact means (10) for supplying electric current to, and/or exchanging electric signals with, the unwinding unit (5) and comprising brush means (11) fixed to the moving ring (4) and arranged to slidably abut conductive bar means (12) fixed to a supporting ring (6) of the supporting carriage (3), drive and control means (40) fixed to the brush means (11) and to the unwinding unit (5) to drive and control the electric motor (37, 38) and comprising a detector device (46) connected to the brush means (11) and configured to detect and record possible supply interruptions of electric current during operation.

1 . A wrapping machine for wrapping a load with a film or band at least one between of plastic and paper material comprising:
 a main frame;   a supporting carriage slidably supported by said main frame and movable along a working direction;   a moving ring rotatably supported by said supporting carriage and rotatable about a wrapping axis parallel to said working direction;   an unwinding unit fixed to said moving ring and provided with a reel of film, pre-stretching rollers to unwind and pre-stretch the film and at least one electric motor to rotate said pre-stretching rollers;   a sliding electric contact assembly for at least one between supplying electric current to and exchanging electric signals with said unwinding unit and comprising a brush assembly fixed to said moving ring and a conductive bar assembly fixed to a supporting ring connected to said supporting carriage, in an operating configuration, said brush assembly slidably abutting said conductive bar assembly to receive electric current and alternatively or additionally to exchange electric signals;   
       wherein said wrapping machine comprises a drive and control system fixed to said moving ring and electrically connected to said brush assembly and to said unwinding unit at least to drive and control said at least one electric motor, said drive and control system comprising a detector device connected to said brush assembly to receive an electric current therefrom and configured to detect and record possible supply interruptions of electric current during operation of the wrapping machine. 
     
     
         2 . The wrapping machine according to  claim 1 , wherein said detector device is configured to detect and record frequency and duration of interruptions of said electric current. 
     
     
         3 . The wrapping machine according to  claim 1 , comprising a central control unit configured to receive from said detector device data related to said supply interruptions of electric current and to determine based on said data maintenance works on at least one between said brush assembly and said conductive bar assembly. 
     
     
         4 . The wrapping machine according to  claim 1 , wherein said drive and control system comprise at least an inverter and a local control unit for driving and controlling the operation of said at least one electric motor. 
     
     
         5 . The wrapping machine according to  claim 4, claim 3 , wherein said drive and control system comprises at least an inverter and a local control unit for driving and controlling the operation of said at least one electric motor and wherein said detector device is connected to said local control unit to transmit thereto data relating to said supply interruptions of electric current, said local control unit being connected to said central control unit. 
     
     
         6 . The wrapping machine according to  claim 5 , wherein said drive and control system comprises a wireless transceiver device for connecting said local control unit to a further wireless transceiver device of said central control unit of the wrapping machine. 
     
     
         7 . The wrapping machine according to  claim 1 , comprising at least one electric backup battery connected to said brush assembly to receive a first electric current, and connected to said drive and control system for continuously powering by said first electric current to said drive and control system even in the event of supply interruptions of said first electric current due to malfunctions of the sliding electric contact assembly. 
     
     
         8 . The wrapping machine according to  claim 1 , wherein said unwinding-unit comprises sensors for detecting operating parameters of said unwinding unit. 
     
     
         9 . The wrapping machine according to  claim 7 , wherein said unwinding unit comprises sensors for detecting operating parameters of said unwinding unit and wherein said sensors are connected to said electric backup battery to continuously receive a first electric current and are connected to a local control unit of said drive and control system for transmitting signals relating to the detected operating parameters of said unwinding unit. 
     
     
         10 . The wrapping machine according to  claim 1 , comprising a containment casing adapted to contain said drive and control system and fixed to said moving ring. 
     
     
         11 . The wrapping machine according to  claim 1 , wherein said conductive bar assembly comprises a plurality of annular conductive bars parallel and adjacent to each other and fixed to an external side wall of said supporting ring and wherein said brush assembly comprise a plurality of contacting brushes each of which being configured to abut slidably a respective annular conductive bar. 
     
     
         12 . The wrapping machine according to  claim 11 , wherein each contacting brush is removably fixed to said moving ring. 
     
     
         13 . A method for wrapping a load with a film or band of at least one between plastic and paper material by means of a wrapping machine that comprises a moving ring rotatably supported by a supporting carriage and rotatable about a wrapping axis, an unwinding unit fixed to the moving ring and provided with at least one reel of film, a sliding electrical contact assembly to supply at least one electric current to and alternatively or additionally to exchange electric signals with, the unwinding unit, said method comprising:
 detecting and recording by means of a detector device connected to a brush assembly of the sliding electric contact assembly possible supply interruptions of said at least one electric current during operation of the wrapping machine;   transmitting data related to said supply interruptions of electric current to a central control unit of said wrapping machine;   based on said data determining maintenance works on said sliding electrical contact assembly.   
     
     
         14 . The method according to  claim 13 , further comprising detecting and recording by means of said detector device frequency and duration of said supply interruptions of electric current. 
     
     
         15 . The wrapping machine according to  claim 2 , wherein said electric current is a first electric current supplied by first annular conductive bars of said conductive bar assembly. 
     
     
         16 . The wrapping machine according to  claim 4 , wherein said local control unit is powered by a first electric current supplied by first annular conductive bars of said conductive bar assembly and said electric motor is powered by a second electric current supplied by second annular conductive bars of said conductive bar assembly. 
     
     
         17 . The wrapping machine according to  claim 16 , wherein said first electric current is a direct current at low-voltage and said second electric current is a three-phase alternate current. 
     
     
         18 . The wrapping machine according to  claim 10 , wherein said containment casing is fixed to said moving ring opposite and facing said unwinding unit. 
     
     
         19 . The wrapping machine according to  claim 12 , wherein each contacting brush is interchangeable with another identical contacting brush.