Cooling device for cooling synthetic filaments

In a cooling device for cooling synthetic filaments using a cooling medium, in particular for use in the spinning of multifilaments, at least one cooling shaft through which the filaments are passed, is arranged between an entry and exit for filaments. The cooling shaft comprises a seamless, electroformed support with passage-openings which are separated by dykes. In this way a uniform flow profile of the cooling medium is obtained in the cooling shaft and the filaments are subjected to a uniform cooling treatment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Preferably, the seamless, electroformed support is made from nickel, with the result that a cooling shaft with a long service life is obtained. In a preferred embodiment of the cooling shaft according to the invention, the passage-opening which are separated by dykes are arranged in a regular pattern. Depending on the particular application, the seamless, electroformed support may comprise a first zone in which there are passage-openings separated by dykes, and a second zone without passage-openings, which adjoins the first zone, as is already known per se from the prior art. In another embodiment, an uninterrupted sleeve is arranged displaceably inside the seamless, electroformed support. This sleeve without openings is used to seal off some of the passage-openings in the electroformed support, so that the amount of cooling air and the location where cooling air enters can be adjusted by the displacement of the sleeve in the seamless electroformed support. The invention also relates to a seamless, electroformed support with passage-openings which are separated by dykes, which is suitable for use in the cooling device according to the invention. The invention also relates to a device for producing synthetic filaments in which a cooling device according to the invention is used, as defined in claim 7 et seq. According to a preferred embodiment of the invention, the extrusion head or the extrusion device used is connected to the entry to the cooling device, and more preferably each spinneret from which monofilaments which are combined to a filament bundle emerge is connected to a cooling shaft of the cooling device. According to a further preferred embodiment of the device for producing synthetic filaments according to the invention, the cooling device used has two outlets for cooling medium, one of which is arranged in the vicinity of the entry end of the cooling shaft and the other of which is arranged in the vicinity of its exit end. In this way, the cooling air supplied is discharged partially in concurrent and partially in countercurrent with respect to the path of the filaments. Such a direction of the air flow promotes the uniformity of the cooling treatment. FIG. 1 shows a diagram for the melt spinning of a polymer, such as PET, during which process PET granules and, if desired, additives are fed via a hopper 1 to a screw type extruder 2 , in which the polymer is melted and than extruded. The extruded polymer is fed to a spinneret 6 via a metering pump 3 , mixing device 4 and filter 5 . The spinneret 6 is provided with a plurality of capillaries, out of which separate jets 7 of molten polymer are forced. The jets 7 of molten polymer are cooled using cooling air (indicated by arrows) in a manner which is to be described in more detail if desired, additives may be applied at the end of tile cooling operation, such as a lubricant, after which the filaments which have been cooled separately in this way are combined to form a multifilament and are wound up for further processing. Further processing of this nature may, for example, comprise the stretching of the yarn in order to obtain the desired orientation in the yarns, and texturing. FIG. 2 shows part of an embodiment of a cooling device according to the invention. A cooling device of this nature comprises a closed housing (not shown) in order to limit disruption to the cooling process caused by variation in environmental factors as far as possible. The housing is provided with an inlet and an outlet for a cooling medium and an entry and an exit for filaments. A cooling shaft 21 , which comprises a cylindrical, thin-walled support 22 which is provided with a regular pattern of passage-openings 23 , is arranged in the housing. The support 22 having passage-opening 23 is produced by means of electroforming as has already been explained above. In the situation shown, the top side of the cooling shaft 21 bears against a spinneret 6 with capillaries 24 , but if desired it may be arranged at a distance therefrom so that a relatively large amount of cooling air can cool the filaments directly beneath the spinneret 6 . A thin-walled, tightly fitting, cylindrical sleeve 25 is arranged displaceably inside the cylindrical support 22 . The cylindrical sleeve 25 , which does not comprise any openings in its wall, is provided with a base 26 with a passage 27 for cooled filaments.