Calender and method for treating web-like materials

Calender for the treatment of web materials (W), comprising a fixed structure (10, 11H, 11K, 300) adapted to support two heated rollers (R1, R2) mutually arranged so as to form a nip (N) that can be crossed by web-like materials (W), wherein each roller (R1, R2) has surface reliefs (RR) arranged according to a predetermined pattern, wherein the rollers (R1, R2) are mutually arranged in a tip-to-tip configuration, such that in an operational setting of the calender the reliefs (RR) of one roller (R1) are radially opposed to the reliefs (RR) of the other roller (R2) in correspondence with said nip (N), wherein each of said rollers (R1, R2) is connected to a drive unit (UM) which determines its rotation with a predetermined angular speed around its own longitudinal axis (r-r), wherein said rollers (R1, R2) are heated by heating means configured to heat individually each roller (R1, R2) of calender, and wherein each roller (R1, R2) undergoes an axial elongation as a consequence of its heating, characterized in that it comprises detection means (E1, E2;

• IS) adapted to detect the axial elongation of each roller (R1, R2) and a programmable control unit (UCP) connected to said detection means and to said heating means, said programmable control unit being programmed to determine the difference between the axial elongations of the rollers (R1, R2) detected by said detection means and emitting an alarm signal if the absolute value of this difference is greater than a predetermined limit value.