JPS5811325B2 - Composite cord for tire reinforcement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is particularly suitable for line reinforcement of carcass plies and annular belt reinforcement of tires used on heavy trucks and earthmoving vehicles.

Such wire reinforcements or cords typically consist of multiple steel strands cabled together to form the desired cord construction, each steel strand being comprised of multiple individual steel strands twisted together. It consists of filaments or wires.

The steel strands are designed to evenly share the loads imposed on the cord during tire operation.

The formation of voids within cabled cords is inevitable.

It has been found that during tire manufacture and operation, moisture trapped within the tire can seep into these cavities and eventually corrode the individual steel wires.

Corrosion is achieved by filling the voids or gaps in the metal cord with some suitable rubber cement or adhesive or a suitable hydrophobic material such as polyolefins such as polyethylene, polypropylene, and co-electrochemical combinations of such olefins. can be prevented or significantly reduced by

It has been discovered that a core made of synthetic polyester fibers, with a centrally located core around which steel strands are wrapped, is very effective in reducing corrosion of the steel wire.

Unfortunately, such cores weaken the strength of the crimp cord because they alone cannot carry the loads that the steel strands can carry.

A typical example of such a cord is found in U.S. Pat. No. 3,765,883, which describes a core specifically designed to break upon unwinding the cabled strands surrounding the core.

The present invention is designed to provide a steel reinforcing cord with a load-bearing center that does not significantly reduce overall strength.

Briefly, the present invention is a steel cord for tire reinforcement, the cord comprising multiple strands of steel cabled or spirally wrapped around a centrally located non-metallic core. The core has a tensile strength that closely approximates that of the steel strands.

The aramid core in the present invention provides three important benefits:

(1) Expanding the cord to allow the rubber to penetrate into the structure of the cord.

(2) Prevent corrosion from spreading to areas other than the cord structure.

(3) Provide a core with considerable strength to contribute to the load-bearing capacity of the cord.

The invention will now be described in detail.

Referring to the attached drawing, which is a cross-sectional view of a tire reinforcing steel cord 5 used for the carcass ply or annular reinforcing belt of tires of large earthmoving vehicles, the same drawing shows a steel cord made of inorganic aramid filaments arranged at the center. A non-metallic core 6 is shown.

A suitable number of stranded steel wires 7-12 are cabled or twisted around an aramid multifilament core 6.

Each of the steel strands 7 to 12 consists of a desired number of twisted steel filaments or strands 13 to 16.

In this case, the individual steel wires 13 to 16 have a diameter of 0.175 millimeters (II) and the steel strands 7 to 12 each have a twist of 10 ioc in the S direction.

The steel strands 7 to 12 have a 19 m width in two directions around the aramid core 6.

Each aramid core 6 has one individual steel strand wire 7 to 1
It has a high tensile strength substantially equal to, or very close to, that of No. 2.

Treated with an agent to strengthen the adhesion between the steel cord 5 and the rubber material to be filled and with a minimum of 1500
Denier aramid multifilament yarn or strand has been successfully used as the core 6.

Two strands of 1000 denier slightly cabled aramid yarn, each similarly treated, have also been successfully used as core 6.

It is important that the aramid core 6 completely fills the centrally located cavity created by the cabled or spirally wound steel strands I to 12.

For such complete filling, the diameter of the aramid core 6 must be at least equal to the diameter of each of the sized steel strands 7 to 12.

In some cases, an aramid core 6 is used which is slightly larger than the steel strands 7-12, and these strands 7-12 are spaced slightly apart so that the steel of the rubber material of the tire is The penetration of the steel cord 5 into the gap is increased, and the individual steel wires 13 to 16 of each of the steel strands 7 to 12 are increased.
to more completely surround the steel wire, thereby reducing voids and reducing the risk of moisture being trapped in the voids and corroding adjacent steel strands.
It is beneficial to do so.

The aramid core 6 should not be so oversized as to severely distort the shape of the copper cord 5 and adversely affect the load bearing capacity of the steel cord 5.

Therefore, the aramid core 6 not only acts as a load-bearing member for the composite steel/inorganic cord 5, but also prevents any moisture from flowing through the cord, and thereby prevents the steel of each strip from flowing. To prevent or significantly reduce corrosion of the individual steel filaments or strands 13-16, the wires 7-120 also fill the central void created by the wrapped steel weave wires 7-12.

As previously mentioned, attempts to use other synthetic fiber cores such as polyester have proven unsuccessful.

Although polyester cores reduced corrosion of the steel strands, they were not strong enough to share the loads or tensile stresses imposed on the reinforcing cords during operation of tires utilizing such reinforcing cords.

Therefore, not only does it help prevent corrosion of the reinforcing steel strands, but it also absorbs a share of the load that is applied to the reinforcing composite cord together with the steel strands. A reinforcing composite cord has been provided that uses a core that acts as a grip.

Such composite cords allow spirally wound cords to be stretched and unwound to allow limited inflation of the tire in the area where the cords are embedded in the tire. This differs from conventional composite cords which utilize low tensile strength breakable cores, or fusible cores or elastic cores to hold them in a coiled relationship until the time comes.

The reinforcing composite cord of the present invention is useful in passenger car tires as well as heavy truck and earth moving vehicle tires.

Although certain representative embodiments and details are shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that the embodiments may be varied without departing from the spirit or scope of the invention. It does not matter if it is changed.

[Brief explanation of the drawing]

The accompanying drawing is a cross-sectional view of a tire reinforcing steel cord used in the carcass ply or annular reinforcing belt of a tire of a large earthmoving vehicle. 5...Composite cord for tire reinforcement, 6...
・Non-metal core, 7, 8, 9, 10, 11, 12...
・Multiple stranded metal wires.

Claims (1)

[Claims] 1. A composite cord for tire reinforcement with a main body made of a corrosion-resistant material, comprising a plurality of metal strands having the same diameter and the same tensile strength, and a substantially circular cord wrapped around the metal strands. an unreinforced non-metallic core having a cross-section and centrally located in said cord, said non-metallic core having a diameter at least equal to the diameter of each of said metal strands; having a diameter large enough to hold the strands in a spaced-apart condition, such that the corrosion-resistant material coats the metal strands and adheres to the strands to prevent the strands from becoming damp. and the non-metallic core maintains the metal strands under tension and spaced apart as described above, and the non-metallic core A composite tire reinforcing cord having a tensile strength substantially equal to the tensile strength of one of said metal strands so as to carry said non-metallic core's share of the load applied to said core.