Patent GB-1466114-A (GB)
Title: Pneumatic tyre
IPC: B60C9/00
Filed: 1974-02-01
Abstract: 1466114 Pneumatic tyre reinforcing cords TOYO RUBBER INDUSTRY CO Ltd 1 Feb 1974 [2 Feb 1973] 04806/74 Heading B7C [Also in Division D1] A steel cord for use as a reinforcement in a pneumatic tyre comprises a plurality of steel filaments of which those filaments exposed to the surface of the cord are coated with a copper alloy, e.g. brass or bronze and at least some of those filaments not exposed to the surface of the cord are coated with aluminium, zinc, an aluminium alloy, a zinc alloy, or a magnesium alloy. A first embodiment of pneumatic tyre includes a radial carcass ply formed from a plurality of cords formed as illustrated in Fig. 1. The cord of Fig. 1 comprises a 3-filament core strand 3, five 7-filament exposed strands 2, and a 1-filament wrapping wire 1. All the filaments are 0À15 mm. in diameter. The core strand 3 is Z twisted with a pitch of 8À6 mm.; each exposed strand 2 is Z twisted with a pitch of 9À7 mm.; the exposed strands 2 are S twisted around the core strand at a pitch of 12À5 mm.; and the wrapping wire is Z twisted at a pitch of 5À00 mm. The non-exposed filaments 4, 4<SP>1</SP> are zinc plated and the exposed filaments 5, and 1 are plated with brass (copper 60%, zinc 31%). A plurality of such cords are rubberized with 10 ends/2À5 cm. The tyre also has four breaker plies having cord angles of + 60, - 20, + 20 and - 20 degrees from the radially inner ply to the radially outer ply. The breaker plies are formed from cords each having a 3-filament core strand (each filament being 0À20 mm. in diameter) with six filaments (each of 0À38 mm. diameter) wrapped therearound. The core strand is Z twisted with a pitch of 9À5 mm. and the six filaments wrapped therearound are S twisted with a pitch of 15À00 mm. Each breaker ply has 13 ends/2À5 cm. The core strand filaments are not exposed to the surface of the cord and are zinc plated, and the six exposed filaments are plated with brass. The carcass and breaker ply cords are rubberized with a compound disclosed in the Specification. In a modified embodiment of the pneumatic tyre previously described, the carcass ply and the breaker plies are formed from cords as shown in Fig. 2. This cord has a 4-filament non-exposed core strand and six 4-filament exposed strands. The core strand is Z twisted with a pitch of 9À00 mm.; the exposed strands are each Z twisted with a pitch of 9À7 mm; and the exposed strands are S twisted around the core strand with a pitch of 13À1 mm. The filaments each have a diameter of 0À175 mm. and the non-exposed filaments 4 are zinc plated and the exposed filaments 5 are brass plated. Alternatively the non- exposed filaments 4 may be coated with a zinc alloy, a magnesium alloy (both specified in the Specification) or aluminium. The Specification disclosed a tyre with twenty two nylon cord carcass plies and two steel cord breaker plies, the cords of which breaker pliers are constructed as illustrated in Fig. 2. In this tyre the non-exposed filaments 4 are coated with an aluminium alloy (specified in detail in the Specification) and the exposed filaments 5 are coated with bronze (copper 93À11%, tin 6À89%). In a further embodiment similar to the first embodiment described above, the non-exposed core strand is not twisted and two of the filaments 4 are plated with zinc with the third plated with brass. Of the non-exposed filaments 4<SP>1</SP>, three are plated with zinc and two with brass.