PURPOSE: To mold a mat having a uniform surface weight distribution by bringing a rotating cleaning brush into contact with a vertically adjustable inverting brushing roller, and feeding back an excess mat forming material.
CONSTITUTION: A vertically adjustable inverting brushing roller 8 is obliquely disposed in a width direction of a mat, rotated in an opposite direction to the moving direction of a mat carrier to form a more uniform surface weight distribution of an intermediate layer of the mat. To clean the roller 8 having flexible bristles made of a plastic material, a reversely rotating brushing roller 17 is brought into contact with the roller 8 at the same inclined position 16. The roller 17 has the same flexible bristles 14 of the plastic material. Excess mat particles are all moved in a direction of an arrow 18, and sent to be returned into a metering receiver of a dispersing head by a suitable conveyor such as a lateral conveyor 33 or the like.