two flow baffles the frequency of the motion back and forth is from 10 to 60 and preferably from 25 to 50 s 1 in one region the fibers are deposited on a support moving in direction b the individual coanda trays 1 2 or 1 39 2 39 are rigidly connected by other baffles 3 and 4 as is shown in diagram 1 and 4 these other baffles 3 and 4 are shaped convexly in the direction of the expander nozzles or can be a simple tube which is engaged by the vibratory drive for the purpose of oscillation or reciprocation at each lower edge of the coanda trays 1 2 or 1 39 2 39 there are arc shaped grooves 6 and 7 the depth at the vertex of the arc shaped grooves 6 7 is about 4 to 6 mm with a base of about 2 5 to 3 cm with reference to a coanda tray that is about 6 cm wide and about 3 cm high as is shown in fig1 and 3 the slit like expander nozzles are positioned in such a way that the longer dimension of the nozzle opening is located in the direction of vibratory motion of the trays 1 2 and aimed below the deflection unit fig2 shows clearly that the deflection of the path of the fibers in the vertex of the recess is very much smaller arrow a i than the deflection at the lower edge of the coanda tray arrow a a of course it is possible to design and dimension the groove differently in the event that there is a slant to the formation of.