Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Patent
1995-10-18
1998-01-13
Johnstone, Adrienne C.
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
57206, 57237, 57311, 57902, 152451, B60C 900, B60C 918, B60C 920, D07B 106
Patent
active
057074674
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to rubber-reinforcing steel cords, particularly to one operation type high elongation steel cords and also relates to a radial tire using these steel cords as reinforcing members. The present invention also relates to an apparatus for manufacturing steel cords in accordance with the present invention.
In the case of the radial tire, reinforcing layers called belts are provided between the tread and the carcass and steel cords serving as composite reinforcing members are embedded in the reinforcing layers.
For such steel cords, there is a tendency to use high elongation cords having an improved anti-cutting property when, for example, the tire runs over a stone or the like.
The above-mentioned high elongation cords are generally classified into multi-stranded type represented by (3.times.7), (4.times.2) and (4.times.4) structures and one operation type represented by a (1.times.n) structure comprising 6 or less base wires. However, the multi-stranded type has the disadvantages that since it requires two or more twisting steps, the productivity thereof is low resulting in a cost increase and further, the weight of the belt layers increases due to increase in the number of twists and in view of these defects, the single operation type is generally more advantageous.
The conventional single operation type has had the structure such that for example, in the case of a (1.times.5) structure, five (5) base wires are twisted in the same direction and at a short pitch. That is, by twisting the base wires to a spring form a shortened twisting pitch, the core (central) portion of the cord is made hollow to thereby secure the elongation of the cord.
However, in order to obtain a high decree of elongation of 4% or more of the cutting load by this system, it is necessary to twist the base wires at an extremely shortened of 6.5 mm for example or to twist them by a multi-operation method as described in the Japanese Laid-Open Patent Publication No. H1-250483. Therefore, it has been usual that the productivity of the cords becomes low and becomes of the short twisting pitch, the twisting loss becomes large so that the efficiency of strength of the steel wires can not be made use of. Moreover, due to the formation of a rubber-impenetrable hollow portion at the center of the cord, the tread of the tire is damaged allowing water to enter into the hollow portion and to pool therein resulting in a corrosion fatigue of the steel cord or separating the cord from rubber against the adhesive strength of rubber.
As a rubber penetration measure, there is proposed in the Japanese Laid-Open Patent Publication H2-68376 and H4-24296 a high elongation steel cord which is twisted at a short pitch and at a slow speed so that gaps are formed among the steel wires.
However, this prior art technique has also had the problems of cost and the lowering of strength of the cord due to a twisting loss because the twisting pitch is short. Further, due to the instability of twisting structure, the gaps among the wires tend to change so that when an external force is applied in the longitudinal direction of the cord at the time of vulcanization of rubber, the gaps are reduced or biased. Therefore, the steel cord tends to get fatigued or fractured due to the stress concentration at the time when the steel cord is buckled. Further, as the wires are twisted loosely to provide large gaps among the wires, when the tire runs over a nail or a metallic strip, it is liable to penetrate into the cord resulting in lowering its external injury-resistant property.
SUMMARY OF THE INVENTION
The present invention has been made to eliminate the above-described problems and accordingly, a first object of the present invention is to provide a compact high elongation steel cord capable of a large elongation at the time of breakage, having a small twisting loss and a favorable degree of rubber penetration yet capable of being manufactured simply and efficiently by one twisting operation.
A second object of the pr
REFERENCES:
patent: 5287691 (1994-02-01), Okamoto et al.
patent: 5319915 (1994-06-01), Kobayashi et al.
patent: 5323595 (1994-06-01), Mizuta et al.
patent: 5337549 (1994-08-01), Kobayashi et al.
patent: 5351470 (1994-10-01), Shinmura
patent: 5457949 (1995-10-01), Bundo et al.
patent: 5472033 (1995-12-01), Kawamura et al.
patent: 5502960 (1996-04-01), Kobayashi et al.
Horikawa Koichi
Matsumaru Kazuo
Johnstone Adrienne C.
Striker Michael J.
Tokyo Rope Manufacturing Co. Ltd.
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