Described herein is a blade unit (10) for industrial fans, which comprises: - a blade (2); and - a tubular bar (4), fixed on which is said blade and which has a root portion (4A) configured for being engaged by means for connecting said bar to the rotor of a fan. The unit is characterized in that it comprises a further bar (6) mounted within said first tubular bar (4) so as to present a first portion (6A) axially constrained to said first bar, and a second portion that is, instead, able to slide with respect to said first bar, in a condition of sliding friction, following upon a deformation due to bending of said first bar.