JPS6038208A - Large-sized pneumatic tire - Google Patents

Abstract

PURPOSE:To improve fatigue resistance by forming a steel cord by winding five or more of side element wires around a core element wire and specifying the shortest distance among said element wires, in the captioned pneumatic tire including a braker part reinforced by a steel cord. CONSTITUTION:A braker part of the captioned pneumatic tire is reinforced by a steel cord consisting of one core element wire 1 and at least five side element wires 3 wound around said core wire forming free spacing 6 with each other. Namely, the constitution of the steel cord satisfies a relation: 1XD+nXd and set such that G falls in the range of 0.015-0.06mm., which is calculated by an equation G=(D+d)sin180 deg./n-d (D= diameter of core element wire 1, d= diameter of side element wire 3, n= number of side element wires 3, and G= shortest distance among side element wires 3). Hereby, a gap part at the central part of a core strand can be removed, and the gaps among side element wires 3 can be filled with sufficient rubber allowing fatigue resistance of the pneumatic tire to be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a large pneumatic tire whose breaker section is reinforced with steel cords.

BACKGROUND ART In recent years, due to improvements in automobile performance and the expansion of expressway networks, automobiles have been driven at high speeds, and steel cords have been widely used in tire breakers as automobile tires that can withstand high speeds.

An example of a steel cord conventionally used in a breaker section is a steel cord in which six side wires are twisted in the opposite direction to the core nutland around the outer periphery of a core strand made of three core wires twisted together. It is. In this conventional cord, the core strands and the side strands are in contact with each other, so the gap between the core strand and the side strands and the gap in the center of the core strand are not filled with rubber. For this reason, when the tread of a tire is damaged due to external injury, water penetrates into the steel cord from the damaged area, and the water spreads through all the gaps in the steel cord, causing rust to form on the steel cord. Rust makes it easy for the breaker layers to separate.

The fatigue resistance of the tire decreases due to the so-called fretting phenomenon caused by friction between the wires and the dirt, and wear of the wires.

In order to improve the penetration of the comb between the side strands, attempts have been made to reduce the number of side strands, reduce the diameter of the lateral strands, or increase the diameter of the core strands by 16. The example shown in FIG. 1 has three core wires 1'? f Six individual strands 3 are twisted in the opposite direction to the twisting direction of the core strands 2 and wound around the twisted core strands 2, and between the side strands 3. Since the gap 4 is formed between the side strands 3, the comb enters between the side strands 3 and the fretting phenomenon between the side strands 3 is reduced, but the fretting phenomenon occurs between the core strand l and the side strands 3. Further, as in the conventional case, the gap 5 at the center of the core strand 2 is not filled with rubber.

In the case of =1-do in FIG. 1, since the core 1-land 2 is made up of three core strands 1, the void 5 in the center of the core 1-land 2 cannot be avoided. Therefore, since the force gap in the center of the core Nutland kh<d, the example in FIG.
Six side strands 3 having the same diameter as the core strand 1 are completely wound around one frame of a core strand 2 consisting of two core strands 1. This code is inside the code
Point 6 is the contact point between the two core wires 1.1, and when the cord is bent, the strain due to bending applied to the core wire becomes large.

It has the disadvantage of low fatigue resistance.

The core wire used in this production is 1 core wire.
A main wire is wound around this one core wire so that at least five core wires have free space between each other,
The void in the center of the core strand is eliminated and (Ill
It is also possible to ensure that the rubber is sufficiently filled between the wires.

That is, this invention provides a pneumatic tire in which the breaker portion is reinforced with a steel cord, in which the steel cord is IXD.
+n
The number of n-side strands, the shortest distance between the G-side strands (1 question) is a humanoid space character characterized by a G calculated from 0015 to 0.06 mm.

An example of the steel cord of this invention will be explained with reference to FIG. , a free space 6 is formed between the side strands 3, and the gap on the center line connecting the adjacent side strands 3.3 is the shortest distance G between the lateral strands.
It is.

In the example shown in FIG. 4, around one core strand l,
The side wire 3 is wound with a width of 6 pieces from the diameter.

30 side wires constituting the steel cord of this invention Number n
It is preferable to have 5 or 6 pieces. The number of side wires η is 4
Book 1. If it is below J, the number of strands constituting the cord will be a little too large, and in order to obtain strong breakage of the cord, it is necessary to use strands with a thick wire diameter, and as a result, the fatigue resistance of the cord will be poor. In addition, when the number n of side strands is 7 or more, the diameter ■) of the core strand l becomes relatively larger than the diameter d of the side strand 8 in order to satisfy O When a large force is applied to the core wire l), the core wire l becomes susceptible to fatigue failure, and as a result, the fatigue life of the cord becomes shorter and longer.

The shortest path l1IllG between the side element wires calculated using the above formula is:
0-015~0.06mmn range, G is 0.01
If it is less than 5 mm, rubber will enter the gap between the side wires LF
ill(<, voids are formed in the cord. Also, if G exceeds 0.06, the shape stability of the cord will be poor, and the cord will easily lose its shape during the processing process, resulting in insufficient performance. Can not do it.

The steel filament used for this Zenmei may be made of ordinary iron material with a carbon content of 065-075%, but it is preferable to use one made of iron material with a carbon content of 075-085%. By increasing tensile strength and resulting cord usage? This reduction results in a lighter tire and improves tire performance. 1 Steel filament is made of copper 60~
The adhesion to rubber is improved by coating with a proportion of 70% brass and 30-40% zinc.

This invention will be explained in detail below.

Examples Various steel cords shown in Table 1 were manufactured using brass-plated Nutyl filaments with a copper/zinc ratio of 65/35.

Table 1 The wire materials in Table 1 are + S'WI Ma582A (carbon content 080-0.85%
) and the conventional product SWf Ma372A (carbon content 0.6
9-0.73%).

The amount of air permeation was determined by inserting a piece of null cord cut into a length of 6 cm into the center of a rubber compound block with a length of 6α, a width of 25α, and a thickness of 250n, and the pressure was 80.
k! The vulcanized block was vulcanized at a pressure of 7/ca, and both lengthwise ends of this vulcanized block were ground with a grinder to a length of k 5 cm, and then compressed air at a pressure of 5 and 4/d was injected into one end of the block. The amount of air flowing out from the other end of the rubber block was measured using a rheometer. The formulation of the rubber compound used in the above air permeation test was as shown in σ below in parts by weight.

(Blank below) The fuel consumption ratio in Table 2 above is the average fuel consumption per month required for the 10) Nta-type trucks installed in each Thailand 67 meeting to make a round trip between Tokyo and Osaka for about one year. ((J/km)
Total tire ratio 3''k 100 and 1 to 4 (low price, average mileage is the mileage at which 1 is completely worn out to all tires on the general road)).

The failure rate when driving on rough roads is the tire failure rate when a large dump truck for transporting crushed stone equipped with each tire was tested running on rough mountain roads 'kfi0000b', and the breaker was separated.

Punctures and complete wear of the core wire form a breakdown of the above failure rate.

The rust occurrence area rate is the value of the fourth layer of the breaker layer after 2000 hours of tire running, and the number of belt cord breaks is the value obtained by disassembling a completely worn tire after running and examining the number of broken cords in the tire. be.

As seen in Table 1.2 above, the tire actual l', actual 2', and actual tire 31 of the embodiment of the present invention have a fuel t1 consumption F ratio,
The tire performance is superior to the comparative tire in terms of average mileage, rough road failure rate, rust area rate, and number of broken Velcito cords. g+, 4782, which has a particularly high carbon content
Code fact consisting of A 1. Thai A1 fruit 1 and fruit 31, which were used three times, are a(i':)i72A with a small carbon content.
It should be noted that the fuel consumption jfc ratio is smaller and the number of belt cord breaks is smaller than that of the tire sample 2/ which uses two cord samples. Cord cross section same figure δ, 6th
Cord ratio shown in the figure], ratio 2 has a large amount of air permeation because the free space 0 deviates from the specified value of the present invention, and the tire ratio 1/=ratio 21 using this cord ratio has significantly inferior tire performance. Although the free space G of the l-da cord (cross-sectional view in Fig. 1) using all three strand core wires is within the range of the specified value of this invention, the tire performance is inferior.

[Brief explanation of the drawing]

3 and 4 are sectional views of a steel cord according to an embodiment of the present invention, and FIGS. 1, 2, 5, and 6 are sectional views of a steel cord of a conventional example or a comparative example. ]: Core strand, 3: Side strand, 7: Free space.

Claims (1)

[Claims] [l] In a pneumatic tire in which the breaker part is reinforced with a steel cord, the steel cord is composed of I diameter of the d-side strand ff
A large pneumatic tire characterized in that G calculated by the number of Jn-side strands and the shortest distance between G-side strands is 0.015 to 0.061ffff. [2] The large pneumatic tire according to claim 1, wherein the number n of side strands is 5 or 6. (8) The large pneumatic tire according to claim 1 or 2, wherein the carbon content of the steel filaments constituting the steel cord is 0.75 to 0.85% by weight. [4] A large pneumatic tire according to any one of claims 1 to 3, wherein the force-heavy portion is reinforced with a polyester cord.