GB1063309A - Method and apparatus for making rods of bonded filaments - Google Patents

Abstract

Bonded rods (particularly for use as cigarette filters) are made in a continuous manner from a bundle of filaments (which have been treated with a bonding agent) by funnelling successive portions of the filament bundle into direct contact with one or more travelling endless belts, the portion of the bundle at any moment in contact with the belt or belts being parallel to the edges of the belt or belts and the belt or belts which envelop this portion of the bundle and carry the bundle through a heating zone. As illustrated in Fig 1 (not shown) five tows 1 of crimped continuous filaments are withdrawn from a supply source and drawn through a bonding jet 2 to form a flat ribbon of uniform width and thickness and over a guide 3 by a pair of feed rollers 4. The bonded tow is withdrawn from the feed rollers, passing over and under wick-type addendum applicators 6 and 6a, by a bustled, cylindrical fluffing jet 7. The plasticized, bloomed tow is then drawn into a forming die 10 through a condensing funnel 8 by means of an endless belt 11. In order to produce a cylindrical rod, the endless belt is formed into a hollow cylinder by the die. The edges of the belt meet in a butt joint, forming a hollow cylinder with an inside diameter equal to the required diameter of the rod. The condensing funnel 8 is provided with a tongue 9 (Fig. 4, not shown) of thin flexible metal which extends inside the belt where the edges are being brought together to keep filaments from getting caught between the edges of the belt as they gradually close. The entrance end of the die 10 is provided with a converging funnel section 12 to permit smooth shaping of the belt and final compaction of the tow. The die is divided into a first section 13 which is heated, a third section 15 which is cooled, and an intermediate section 14 having neither heating nor cooling. To facilitate the use of a seamless, endless belt all sections of the die are divided longitudinally into sections 13a and 13b as shown in the enlarged cross-sectional view (Fig. 2, not shown). An alternative construction, also permitting the use of a seamless belt, is illustrated in Fig 3 (not shown) in which the section 13 is provided with a slot 13c for the insertion of the belt 11. The belt is moved by the drive pulley 16 and otherwise guided by the idler pulleys 17a to 17d. The finished bonded rod 18 emerges from the discharge end 11a of the belt and enters a final sizing die which may be surrounded by a cooling jacket. The rod is pulled through the finishing die by a pair of grooved rollers 19 which may be replaced by a short endless belt which envelopes the rod in the same manner as the forming belt. As illustrated in cross-section in Fig. 5 (not shown) two belts 32 and 33 may be used in a forming section 34 to produce a cylindrical rod, each belt covering one-half the periphery of the rod, the section 34 being provided with a slot 34a for the insertion of the belts into the interior of the section. Figure 6 (not shown) depicts an arrangement for forming a rod of square cross-section by the use of four belts 21 to 24 passing through a forming section comprising a lower section 35 and a removable upper section 36.