Pre-stretching roller, method of manufacturing the pre-stretching roller and winding apparatus

A pre-stretching roller of an unwinding apparatus associable to a wrapping machine, comprising a main body elongated along a longitudinal central axis and manufactured by an extrusion process and including:

• a first tubular element having a cylindrical shape and defining an external cylindrical wall suitable for interacting with a film;
• a second tubular element internal to said first tubular element and having a first end provided with a first seat suitable for receiving and coupling with a driving shaft of a driving assembly of said unwinding apparatus and an opposite second end provided with a second seat suitable for receiving and coupling with a supporting pin for fixing said pre-stretching roller to said unwinding apparatus;
• a plurality of longitudinal vanes, parallel to said central axis and which connect said first tubular element to said second tubular element;
• wherein said second tubular element comprises a plurality of longitudinal ribs each longitudinal rib being connected to a respective longitudinal vane.

A method for manufacturing a pre-stretching roller of an unwinding apparatus comprising the steps of:

• extruding a main body, elongated along a longitudinal central axis and comprising:
• a first tubular element having a cylindrical shape and defining an external cylindrical wall adapted to interact with the film;
• a second tubular element internal to said first tubular element and provided with a plurality of longitudinal ribs;
• a plurality of longitudinal vanes, parallel to said central axis and which connect said first tubular element to said second tubular element, wherein each longitudinal rib of said second tubular element is connected to a respective longitudinal vane;
• making on a first end of said second tubular element a first seat suitable for receiving and coupling with a driving shaft of the unwinding apparatus suitable for rotating said pre-stretching roller;
• making on an opposite second end of said second tubular element a second seat suitable for receiving and coupling with a supporting pin for fixing said pre-stretching roller to said unwinding apparatus.

An unwinding apparatus associable to a winding machine for dispensing a film with which to wrap a load, comprising at least a pair of pre-stretching roller suitable for unwinding from a reel and then pre-stretching a film and a driving assembly for rotatably driving said pre-stretching rollers, each pre-stretching roller comprising a main body elongated along a longitudinal central axis and obtained by an extrusion process and including:

• a first tubular element having a cylindrical shape and defining an external cylindrical wall suitable for interacting with the film;
• a second tubular element inside said first tubular element and having a first end provided with a first seat suitable for receiving and coupling with a respective driving shaft of the driving assembly and an opposite second end provided with a second seat suitable for receiving and coupling with a supporting pin of said unwinding apparatus;
• a plurality of longitudinal vanes, parallel to the central axis and connecting said first tubular element to said second tubular element;
• said second tubular element further comprising a plurality of longitudinal ribs each longitudinal rib being connected to a respective longitudinal vane.