is held tensioned so that a satisfactory smoothing of the felt roll is achieved this also makes it possible to reduce the distortion of the rolls in the case of products with a large thickness on which it is difficult to flatten the final turn satisfactorily this final phase of between time t 2 and time t 3 takes place preferably during a period corresponding to at least three complete revolutions of the felt roll this slowing down causes a considerable difference between the speed of rotation of the felt roll and the speed of the compressor roller which facilitates the removal of the felt roll via the inclined plane 12 as soon as the conveyor 7 has been retracted as is shown more particularly in fig3 4 the roll obtained consists of uniform turns which are coiled about generatrices of concentric cylinders to test the efficiency of a process of this type for forming rolls strips of glass fibers of 11 m in length 1 20 m in width and 80 mm in thickness were coiled and rolls of 500 mm in diameter were formed corresponding to a compression ratio of 4 5 the strips were then unrolled and cut into squares if the procedure according to state of the art fig2 or according to the invention is carried out a resumption of the average thickness of 129 is obtained in both cases on the other hand the dispersion of the measurements is much greater in the first case deviation type 8.