Method and apparatus for the manufacture of cigarette filters containing particulate material

An apparatus for the manufacture of cigarette filters containing particulate material, from plasticized filter material composed of thermoplastisity filaments, comprising:

• a first pair of rolls, between which a first gap is defined, said gap having a substantially oval cross section, said filter material being fed through said first gap and being formed so that the transverse cross-section thereof is changed to a substantially oval shape;
• a second pair of rolls, between which a second gap is defined, said gap having a cross-section wherein two campaniforms are arranged symmetrically and connected to each other, one of said second pair of rolls having projections on the peripheral edge thereof for forming pockets, said filter material being fed through said second gap and being formed so that the transverse cross section thereof is changed to a shape wherein two campaniforms are arranged symmetrically and connected to each other and at the same time pockets are formed on the surface of said filter material;
• means for depositing particulate material in said pockets;
• means for folding and closing said filter material so that the deposited particulate material is positioned in the interior of said filter material;
• and,
• means for wrapping said filter material with wrapping sheets.