The folding press provides two blades 7 and 8 which are supported and actuated by a cutter block 6 which is C-shaped and which is movable in the vertical direction with respect to two counterblades 1 and 5 between which the plate 19 is placed. The cutter block 6 is actuated by one or more cylinders 9 of the fluid-dynamic type and and in its rear part has rolling elements 14 and 15 which move on tracks 16 and 17, the latter extending essentially in the vertical direction and having curved portions 18 at the extremities. The rolling elements travelling on the tracks cause the cutter block 6 to make a motion of curvilinear shape, a fact which causes the operation of the blades 7 and 8 and the folding of the plates. There are also provided an eccentric structure 12 and a pivot 13' which are capable of varying the position of the cylinders 9 so as to vary the folding angle of the border of the plate 19 upwardly or downwardly, the folding being determined respectively by the lower blade 8 and by the upper blade 7.
