Folding roller and machine comprising said roller

A folding roller with a rotation axis, comprising

• at least one gripping member extending longitudinally along the folding roller and
• at least one piezoelectric actuator for controlling a pivoting movement of the at least one gripping member about a pivoting axis thereof parallel to the rotation axis of the folding roller;
• and
• wherein said at least one piezoelectric actuator comprises
• an active piezoelectric element contained in an amplification member of deformations of the active piezoelectric element caused by a voltage applied to said active piezoelectric element, wherein the amplification member comprises a deformable frame, which amplifies the deformations of the active piezoelectric element caused by an electrical voltage applied to said active piezoelectric element.

A folding machine comprising

• at least a first feed path for feeding at least a first web material toward a folding unit, and
• members for forming packs of folded sheets produced from the web material;
• wherein the folding unit includes
• a first folding roller with a rotation axis;
• wherein the first folding roller comprises
• at least one gripping member extending longitudinally along the first folding roller, and
• at least one piezoelectric actuator for controlling a pivoting movement of the at least one gripping member about a pivoting axis thereof parallel to the rotation axis of the first folding roller;
• wherein the at least one piezoelectric actuator comprises an active piezoelectric element contained in an amplification member of deformations of the active piezoelectric element caused by a voltage applied to said active piezoelectric element;
• and
• wherein the amplification member comprises a deformable frame, which amplifies the deformations of the active piezoelectric element caused by an electrical voltage applied to said active piezoelectric element.

A folding machine comprising

• at least a first feed path for feeding at least a first web material toward a folding unit, and
• members for forming packs of folded sheets produced from the web material;
• wherein the folding unit includes
• a first folding roller with a rotation axis;
• wherein the first folding roller comprises
• at least one gripping member extending longitudinally along the first folding roller, and
• at least one piezoelectric actuator for controlling a pivoting movement of the at least one gripping member about a pivoting axis thereof parallel to the rotation axis of the first folding roller;
• and
• wherein the at least one piezoelectric actuator comprises an active piezoelectric element contained in an amplification member, wherein the deformations of the active piezoelectric element caused by a voltage applied to said active piezoelectric element are amplified to obtain desired displacement of the piezoelectric actuator.