Unit for converting a continuous web substrate, and packaging production machine thus equipped

A method of operating a conversion unit, the conversion unit converting a continuous web into separated converted blanks of predetermined length, the method comprising:

• engaging the continuous web by a first motorized arrangement and driving, as a first run driving, the continuous web at a clocked speed;
• receiving from the first motorized arrangement the continuous web by a second motorized rotatable arrangement and driving, by the second motorized rotatable arrangement as a second run driving, the continuous web;
• receiving the continuous web from the second motorized arrangement by a sheeter adjacent the second motorized arrangement, and cutting, by rotary tools of the sheeter, the continuous web into separate blanks;
• converting, in at least one web conversion station, the separate blanks into the separated converted blanks;
• varying a speed of rotation of the second motorized rotatable arrangement in phases, the phases including:
• a constant speed phase at a constant tangential speed, which is substantially equal to a speed of rotation of the tools of the sheeter, wherein a cut of the continuous web substrate is made by the sheeter during the constant speed phase of the second motorized arrangement;
• a speed reduction phase, during which a length of the continuous web substrate, which length is dependent on the difference between the length of the blank and a peripheral extension of the rotary conversion tools, is kept upstream of the second motorized arrangement;
• and
• a speed increase phase, during which the continuous web substrate is discharged downstream of the second motorized rotatable arrangement to the sheeter.