United States Patent (19) 11 Patent Number: 4,807,680 Weidenhaupt Et Al
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United States Patent (19) 11 Patent Number: 4,807,680 Weidenhaupt et al. 45 Date of Patent: Feb. 28, 1989 54 PNEUMATIC TRE INCLUDING 58 Field of Search ............... 152/451, 526, 527, 539, RENFORCNG ROPE MADE OF AT LEAST 152/540, 556, 557, 560; 57/210-213, 215-217, TWO DIFFERENT MATER ALS 222, 244, 250, 258, 223, 229, 236-238, 240,902 75 Inventors: Wolfgang Weidenhaupt, Erkelenz; 56 References Cited Gunther Wepner, U.S. PATENT DOCUMENTS Waldfeucht-Neuhaaren; Peter 3,154,910 1 1/1964 Dietz ..................................... 57/214 Dismon, Heinsberg-Proselen, all of 4,176,705 12/1979 Russell et al. .................... 57/220 X Fed. Rep. of Germany; Mattheus G. 4,234,030 1 1/1980 Nieuwal et al. ..... ... 152/557 X Remijn, Velp, Netherlands 4,349,063 9/1982 Kikuchi et al. ................... 57/215 X 73 Assignee: Akzo NV, Arnhem, Netherlands Primary Examiner-Michael W. Ball Assistant Examiner-Thomas Bokan 21 Appl. No.: 938,056 Attorney, Agent, or Firm-Michael J. Striker 22 Filed: Nov. 17, 1986 57 ABSTRACT A pneumatic tire includes a composite rope made of a Related U.S. Application Data cylindrical core of twisted filaments of aromatic poly 63 Continuation-in-part of Ser. No. 610,875, May 16, amides around which a plurality of steel wires of a 1984, abandoned. rectangular configuration are coiled. The steel wires are wound side-by-side in one layer. Each wire is twisted (30) Foreign Application Priority Data around its own axis to such a degree that its broader side May 16, 1983 DE Fed. Rep. of Germany ....... 3317708 fully engages the periphery of the polyamide core. The Mar. 23, 1984 DE Fed. Rep. of Germany ....... 3410703 edges of respective wires are rounded whereby the convex narrow sides of adjoining wires contact one (51 Int. Cl." ............................................... D02G 3/48 another substantially along a line. I52 U.S.C. ...................................... 152/451; 57/212; 57/216:57/902; 152/527 19 Claims, 7 Drawing Sheets FORCE (N) U.S. Patent Feb. 28, 1989 Sheet 1 of 7 4,807,680 FORCE (N) FORCECN) U.S. Patent Feb. 28, 1989 Sheet 2 of 7 4,807,680 FORCE (N) FORCE (N) 64O 29 O U.S. Patent Feb. 28, 1989 Sheet 3 of 7 4,807,680 Z U.S. Patent Feb. 28, 1989 Sheet S of 7 4,807,680 F G. 8 U.S. Patent Feb. 28, 1989 Sheet 6 of 7 4,807,680 NSN No NYNN NASA NNN U.S. Patent Feb. 28, 1989 Sheet 7 Of 7 4,807,680 4,807,680 2 300 N and the component filaments of aromatic poly PNEUMATIC TRE INCLUDING RENFORCNG amide have a breaking strength of 650 N, then the rein ROPE MADE OF AT LEAST TWO DFFERENT forcing rope of this invention has a breaking strength of MATER ALS about 950 N. In keeping with these objects and others which will This application is a continuation-in-part of applica become apparent hereafter, one feature of the invention tion Ser. No. 610,875 filed May 16, 1984, now aban resides in the provision of a reinforcing rope made of at doned. least two components of which the first component BACKGROUND OF THE INVENTION consists of steel wires and the second component of O filaments of aromatic polyamide whereby the polyam The present invention relates to a pneumatic tire ide filaments form a core of a substantially circular including a reinforcing rope made of at least two com cross-section around which the steel wires are coiled, ponents, whereby one component consists of steel wires each of the steel wires having an approximately rectan and the second component of fibres of p-aromatic poly gular cross-section with rounded edges and defining amides. - 15 opposite broad and narrow sides and the broad sides of A reinforcing rope of this kind is described in U.S. respective coiled steel wires extending in the circumfer Pat. No. 4,176,705. The prior art reinforcing rope is ential direction of corresponding sections of the poly composed of a plurality of twisted strands of round steel amide filaments core. In the preferred embodiment, wires coiled around a multi-filament core of aromatic material of the aromatic polyamide core is particularly polyamide. In order to keep the steel wire strands in 20 poly-(p-phenylenterephthalamide). mutually spaced relationship, breaking strength of re If has been found that the structure of the composite spective strands is set equal to that of the core. How rope of this invention surprisingly results in a substantial ever, if such a prior art rope is exposed to a tensile load, increase of the breaking elongation of the steel wires the core filaments of aromatic polyamide share the load component. with the steel wires whereby the polyamide core fila 25 Preferably, the steel wires are made of drawn steel ments are exposed to extremely strong transverse forces having 0.6 to 0.9% by weight of carbon contents. Steel exerted by the steel strands. The effect of the transverse wires of round cross-section made of steel material of forces is very disadvantageous because the larger is the the aforementioned carbon contents have a highly ten tensile load the larger is the extension and hence the sile strength between 2,500 to 3,500 N/mm2 and a stronger is the effect of transverse forces. 30 breaking elongation of about 2%. As known, steel wires have a lower breaking exten Since such very strong round wires are suitable for sion than have the filaments of aromatic polyamide. withstanding high loads, they are employed as compo Consequently, the prior art composite reinforcing rope nent parts in composite reinforcing ropes which are can be exposed to such a load only at which its exten designed to exhibit a high ultimate tensile strength. The sion does not exceed the breaking extension of the steel 35 specific tensile strength of the reinforcing rope related wire strands. If this limit load is exceeded, the steel to its own weight is advantageously increased by using wires rupture and the entire load is taken up by the the before described round wires. polyamide core which in turn immediately exceeds its Depending on the number of windings or twists of own breaking elongation and ruptures too. In other such steel wires of a rectangular cross-section with words, the known composite rope breaks when its ex rounded edges, per a length unit of the core, the result tension corresponds to the breaking extension of its steel ing composite rope of this invention may surprisingly wire component in spite of the fact that the latter is achieve a breaking elongation over 4%. Preferably each distinctly below the breaking elongation of the polyam of the steel wires is coiled around the core and twisted ide core. along own longitudinal axis with 40 to 200 windings and Since the breaking elongation of the prior art rein 45 twists per meter. The resulting rope has approximately forcing rope is smaller than the sum of breaking elonga a circular cross-section. tions of its component parts, the excellent strength of In order to reduce frictional wear between adjoining the core filaments of aromatic polyamide is utilized only steel wires resulting in the so-called fretting corrosion, partially. it is advantageous when adjoining steel wires are in 50 contact with one another along a line. In establishing SUMMARY OF THE INVENTION such linear contact with steel wires having a rectangu It is therefore a general object of this invention to lar cross-section, it is necessary that the edges of the avoid the above described disadvantages. wires be well rounded. More particularly, it is an object of this invention to The cross-sectional area of each steel wire is prefera provide an improved composite reinforcing rope whose 55 bly between 0.03 and 0.2 mm2 and the ratio of the broad breaking elongation matches that of its polyamide fila sides to the narrow side of each wire cross-section is ment COre. between 1 and 4. It is namely possible to use steel wires Another object of this invention is to improve the having an approximately square cross-section (ratio of design of the composite reinforcing rope in such a man rectangular sides equals 1), with rounded edges or cor ner that the breaking elongation of its steel wires com cS ponent approximates that of its core of polyamide fila The arrangement of steel wires in the outer layer of ments and, at the same time, the steel wires apply the reinforcing rope has the advantage that the steel against the core filaments only minimum transverse wires which are usually coated with brass, have a par forces during a tensile load. The composite reinforcing ticularly strong adherence to the elastomeric material. rope of this invention breaks only under a force which 65 By the provision of steel wires of a rectangular cross corresponds approximately to the sum of breaking section with rounded corners and by orienting the forces of respective component parts. For example, if broad sides of the wires in circumferential direction of the component steel wires have a breaking strength of the approximately cylindrical center core, an approxi 4,807,680 3 4. mately circular cross-section of the rope is ensured. By cant must not exhibit any chemical aggressivity against rounding the edges of the rectangular steel wires a steel and aramid leading to the corrosion of the steel for contact along a line is established between the adjoining example; and must not have any negative effect on the wires so that frictional areas are reduced in advanta binding between the reinforcing rope and the elasto geous manner to minimum.