Abstract: Plane, rectangular sheets (10) are moved through between a driven bending roll (32) and a plurality of back-up rolls (34) and are bent round the bending roll (32) by these rolls and a plurality of pressure rolls (52, 56) disposed behind the bending roll (32) and back-up rolls (34). The almost completely rounded sheet (10) is bent resiliently away from the bending roll (32) by a deflecting member (62) as a result of which the front edge (10a) of the sheet is prevented from re-entering the gap between the bending roll (32) and the back-up rolls (34) before the rear edge (10b) of the sheet has travelled through this gap. Then the deflecting member (62) is moved back into its position of rest so that the front region of the sheet (10) springs back in the direction of the bending roll (32) and as a result is again gripped by the bending roll (32) and the back-up rolls (34) and moved through between them.