Machine for forming fiber webs

Claim 1

In a machine for forming random fiber webs, having a first rotary foraminate condenser, means for delivering airborne fibers onto said first condenser to form a fiber mat on said first condenser, a rotary lickerin mounted beneath said first condenser, means for doffing the mat from said first condenser and feeding the mat to the lickerin so that the lickerin in its rotation combs fibers from the mat, a cylindrical saber mounted in spaced, confronting relation to said lickerin to assist in doffing fibers therefrom, and an endless foraminate condenser whose upper reach at least travels in a horizontal plane beneath said lickerin, the improvement comprising a pair of tapered, vertically disposed ducts positioned one above the other with their narrow ends opening on the space between said lickerin and said saber, said space forming a venturi section between said ducts, and the lower of said pair of ducts extending from said venturi section to and above the upper reach of the last-named condenser, pneumatic means for creating a high velocity air stream in said lower duct to doff fibers from said lickerin and to convey the doffed fibers in a vertically downward direction onto the upper reach of said last-named condenser, said pneumatic means including means for recirculating said air stream downwardly through the upper of said ducts and tangentially past said lickerin and into the upper end of said lower duct, after the stream has passed through the upper reach of said last-named condenser, and means for controlling the air flow in said ducts to minimize turbulence in said lower duct, including means eccentrically mounting said saber for rotational adjustment selectively to vary the distance between said saber and said lickerin, and means for controlling the supply of air to said ducts.