Abstract: A bundle of hollow fibers of uniform diameter, particularly for use in dialysis is formed of a plurality of parallel hollow fibres at least a part of which, prior to the formation of the bundle, is permanently undulated by means of interleaved undulating elements moving opposite the feeding direction of freshly extruded fibres. The undulating elements are in the form of cylindrical rods having a substantially larger diameter than the outer diameter of the fibres so that the wavelength and amplitude of the resulting undulations are substantially larger than the outer diameter of the fibres.

Abstract: Disclosed is a method of and a device for producing bundles of hollow fibers such as used for dialysis. The device includes a guiding device for a continuous fiber which rotates in a plane. At least two groups of take-up elements are mounted on a conveyor. The conveyor is intermittently activated so that a group of take-up elements is placed in a working position in the range of movement of the guiding device, and a strand of a desired thickness is wound around the take-up elements. Thereafter, the conveyor is activated to discharge the first group together with the completed strand from the working position and place the subsequent empty group of take-up elements in the working position, without interruption of movement of the guiding device. During the winding-up of the subsequent strand, the completed strand is cut and wrapped into bundles.