carding drum 17 turning during operation in the direction indicated by an arrow 18 and carrying at its periphery a layer of fibres 19 which is constantly renewed by means which are not represented part of the layer 19 is picked up by a doffer 21 which with the fibres taken forms directly or indirectly the fibre web 6 as explained in detail in fr a 2 770 855 the thickness of the fibre web 6 can be varied by varying the rotation speed of the drum 17 or of the doffer 21 or else by varying the distance between the drum 17 and the doffer 21 fig5 more particularly illustrates the production of a fleece having on leaving the crosslapper a profile with tapering edges by means of a fibre web 6 which instead of having a uniform thickness has zones z 1 and z 2 in which the surface weight of the fibre web represented by the thickness in fig5 diminishes up to a fibre web cross section 22 and then increases again these zones z 1 and z 2 are positioned along the length of the fibre web 6 in such a way that the lapper carriage 9 places these along the left edge and right edge respectively of the fleece 16 the fiber web cross section 22 having the smallest surface weight coincides with the corresponding edge of the fleece 16 the needle loom 3 installed downstream of the crosslapper 2 and in particular of its delivery belt 8 relative to the direction of circulation 23 of the latter transforms the intermediate fleece 16 constituted of superposed segments of fibre web 6 into.