Abstract: A first aspect of the present invention relates to a filament (11; 12), especially for reinforcing rubber articles. Said filament (11; 12) features a contact surface (14) and an outer surface (13). In a second aspect, the invention relates to a steel cord (10) comprising two of said filaments (11, 12), the contact surfaces (14) are arranged adjacent to each other. The outer surfaces (13) are configured arcuate shaped and provide a smooth outer contour (15) of the steel cord (10). Due to said construction the largest dimension (d) of the steel cord (10) and the thickness of a rubber coating (18) may be considerably reduced. Additionally the invention relates to a method of producing a steel cord (10) and to a tyre (20) comprising a carcass ply (22) and/or at least one belt (25; 26) including said steel cords (10).

Abstract: The invention relates to a false twister (10), especially for producing spiral filaments. The false twister comprises a rotatably driven twister (17) with at least one guide roller (18) around which the filaments (11) are wrapped. The aim of the invention is to reduce the forces that act upon the spiral filaments (11′). To this end, at least one guide roller (18) is driven. According to a method for producing spiral filaments (11) the power necessary for moving the filaments (11) through the false twister (10) is at least partially applied on the filaments (11) in the false twister (10).

Abstract: For reinforcing rubber or plastics articles, particularly pneumatic tires, a wire filament is proposed which is spirally shaped and exhibits no elastic residual torsional stresses. A wire filament 8 according to the invention is produced by twisting drawn straight wire filaments 2 into the range of plastic deformation with subsequent return-twisting, at least two wire filaments being brought together and combined prior to return-twisting. Preferably at least two wire filaments 2 are brought together by means of a perforated disk 30, twisted about each other and plastically deformed in a false twister 20 and subsequently return-twisted in a further false twister 40.

Abstract: Process for producing a steel cord for pneumatic tires comprising a bunch of wires, the core of which consists of wire filaments 10 arranged bunched juxtaposed in parallel. Preferably at least three wire filaments 10, 20 are provided, at least two wire filaments located juxtaposed in parallel being spirally shaped as core filaments 10 forming a core 60 and at least one wire filament spirally surrounding the two core filaments 10 as a sheathing wire 20. Spirally shaping the wire filaments 10 is achieved in accordance with the invention by false twisters 40. Due to this spiral shaping of the wire filaments 10 migration of the filaments from the core composite is avoided more particularly. The residual torsional stresses of the core filaments among each other and in conjunction with the restoring forces of the sheathing wire are advantageously cancelled. In addition, the steel cord features to advantage a flattened, more particularly, oval shape.