Unwinder for web material and method for controlling the unwinding of web material

A method for controlling the unwinding of web material, comprising:

• pulling, by an actuator, a web material unwound from a first reel along a feeding path and in sequence through a junction device and a dynamic storage device located between said first reel and said actuator;
• wherein, in the dynamic storage device, the web material is arranged to zigzag around at least a first return roller and around at least a second return roller, mounted idle on a carriage free to move towards or away from the first return roller;
• decreasing a speed of the web material unwound from the first reel in a portion placed at the junction device and splicing an end portion of the web material running low on the first reel to an initial portion of a web material of a second reel maintaining a constant delivery speed of the web material downstream of the dynamic storage device by approaching the carriage to the first return roller caused by the traction exerted by said strip material;
• conferring to the web material unwound from the second reel a speed greater than the delivery speed to move away the carriage from the first return roller under the weight of the carriage;
• and
• rotating, through at least one motor and in a direction consistent with a feed direction of the web material, at least one motorized shaft on which said at least one first return roller is idly mounted.