Abstract: In an apparatus for winding up flat material webs or foils, by means of a rotary winding cylinder, the cylinder is provided with a longitudinal slot and which accommodates a clamping device and by which a portion of the web to be wound up and introduced through the slot by means of a vertically movable blade which causes the web to be seized and firmly held. Upon finishing a roll, the seized portion of the web is disengaged and the roll can be withdrawn by means of a take-off device. This makes it possible to wind up the web at a high speed without forming folds. Also, the laps of the formed roll are very firmly wound and their edges are throughout in a definite position so that they may be heated in a working station.