JPS5947073B2 - air tires - Google Patents

Description

[Detailed Description of the Invention] A conventional pneumatic tire is composed of a carcass ply fixed to a pair of bead wires and a breaker that provides rigidity to the tread. Among these parts, the carcass ply is made of cotton, rayon, nylon, Progress was made sequentially with polyester and steel, followed by breaker cotton, rayon, nylon, vinylon, and steel.Tire structure also progressed with bias tires, belted bias tires, and radial tires.

Despite the advances in carcass ply, breaker, and tire structure as mentioned above, the bead wire that fixes the carcass ply has a carbon content of around 0.7% and a tensile strength of 190 to 200. Bead wires with m4 shear impact energy of 115 to 125 Ky/d have been used until now without any changes.

On the other hand, from the perspective of required performance for tires, high speed, mass transportation,
In addition to safety, tires with low fuel consumption are required from the viewpoint of energy conservation, and for this reason radial tires are becoming popular.

Bead wire is made from hard steel wire, and in order to maintain sufficient bead strength during the tire bead design stage, a large amount of bead wire must be used, but since the specific gravity is high, it reduces tire weight and fuel consumption. It was becoming an obstacle for me.

In addition, pneumatic tires that use a large amount of bead wire like this are susceptible to shocks perpendicular to the longitudinal axis of the bead wires, such as when running on the shoulder of the road while driving, or when the crowbar is forcibly hit with a hammer when assembling the rim. As a result, the bead wires were sometimes cut.

The pneumatic tire of this invention uses a new high-strength bead wire to reduce the amount of bead wire required for design strength compared to the conventional one, thereby reducing tire weight.
It provides pneumatic tires with low fuel consumption,
In addition, it is possible to provide a pneumatic tire that is excellent in performance and economy by improving the impact resistance of the tire bead, reducing the volume of the tire bead, and improving the efficiency of the bead grommet winding process. It is a purpose.

To explain this invention in detail, the carbon content in the steel wire rod used as the bead wire material has a great effect on its physical properties, and conventional hard steel wire rods, such as JIS-8W
Even if the tensile strength of RH72A material (carbon content 0.69 to 0.76%) is increased by reducing the area reduction rate of cold wire drawing, there is a limit, and the fatigue resistance and shear impact resistance are poor. It is difficult to use, while 5WFLS 92A (carbon content 0.90-0.
95%), only a wire with poor toughness is obtained.

In order to achieve the tensile strength, toughness, and shear impact resistance required for bead wire, the optimal carbon content is 0.75 to 0.90%, considering the wire drawing area reduction rate and heat treatment conditions. If it is too low, it will have poor shear impact resistance and will not exhibit sufficient tensile strength; if it is too high, it will lack toughness, and in extreme cases it will break by bending.

On the other hand, the value of tensile strength 220~240~/mr7i was derived from the required performance of the tire, and 220 has a value of 9/-
If the tensile strength is lower, the tire weight reduction effect will be less.

In other words, in some tires, n rows of parallel bead wires are stacked in m stages and wound around a bead grommet, but if the tensile strength is low, one row or stage may be omitted and the tire If an attempt is made to reduce the weight of the tire, the desired strength of the bead grommet will not be achieved, making it impossible to reduce the weight of the tire.

Wires with tensile strengths exceeding 240 to 9/- are also easily made, but they lack toughness and are prone to breakage during the bead winding process.

Next, the shear impact energy of the bead wire is 130Ky.
/d or more, and if it is less than 130Ky/d, the bead wire will become brittle and will easily break when assembling the rim, and even if the rim can be assembled, it will easily break when the tire runs onto the shoulder of the road while driving. Dangerous and unusable.

The above shear impact energy was measured using a Charpy type impact tester with a sample length of 9.6 degrees, a hammer part having a 60 degree angle and a cutting edge curvature of 0.45 meters, and an arm length of 5 meters.
The value measured with 0 crrL and hammer weight soo, p = calculated using the following formula.

Shear impact energy (KS?/C11F) In the above formula, W is the weight of the hammer, L is the hammer length,
θ is the arm swing angle after sample destruction, θ0 is the arm swing angle when no sample is attached, l is the sample length), and S is the sample cross-sectional area (d).

Next, the present invention will be specifically explained using examples.

Example wire diameter 0.96. Three types of bead wires shown in Table 1 were made using W steel wire.

0 amount of futanzu (93% copper, 7% tin) attached to the above wire
．． 45 g/? It was plated with

Wire A in Table 1 is the wire conventionally used for bead wire, B is the wire of the pneumatic tire of the present invention,
C is an ultra-high strength wire.

Note that the fatigue limit stress (Kp/mA) in Table 1 above is a value measured by a Hay-Robertson rotary bending fatigue tester.

Next, bead grommets were made using each of the wires shown in Table 1 and the following compound.

Is the starting diameter of the grommet 1665? ? The number of aligned wires and the number of stages in Z are as shown in Table 2.

Rubber compound SBR, 50 parts by weight NR, 50 parts by weight zinc white 3 parts by weight Stearic acid 2 parts by weight FEF carbon 40 parts by weight GPF carbon 40 parts by weight Aromatic oil 20 parts by weight Sulfur 15 parts by weight Accelerator MSA 1 part by weight Skotsuk
0.8 parts by weight Using this bead grommet, the carcass is polyester 1500d/2.23 end, 4 ply, and the breaker is 3X0.20+6X0
．． 38.13 end, molded and vulcanized as 4 pieces, 100O
Ten R and -20 radial tires were made.

The performance of the tires is shown in Table 3 below.

The fuel consumption ratios in Table 3 show the travel distance and fuel consumption km/l when each tire is attached to an 11-ton car and the vehicle runs at high speed between Tokyo and Osaka, with TA-1 being 100.

The bead impact resistance ratio is determined by dropping a blade with a blade angle of 60 degrees and a weight of 20 to 7 (blade curvature i, 5 m) onto the tire bead, and from the falling distance and weight of the blade when the bead breaks. Kinetic energy is shown with TA-1 as 100.

The burst water pressure ratio is the water pressure at which the tire breaks when the tire is assembled on a rim and water is injected instead of air.TA-1 is 100.
Shown as

As shown in Table 3 above, the TB-1 tire of the present invention has higher bead wire strength than the conventional TA-1 tire, resulting in lower fuel consumption, higher impact resistance, and higher burst water pressure.

Furthermore, although the TB-2 tire uses a lower bead weight and has a lower bead strength than the TA-1 tire, it has low fuel consumption, excellent impact resistance, and burst water pressure.

On the other hand, TO-1 and TO-2 tires have low heat consumption because they are made of high-strength bead wire, but both have high impact resistance and
Inferior to bursting water pressure.

It should be noted that the shear impact energy in Table 1 is B/A
= 1.17 times, the bead impact resistance of tires using these tires with the same structure is TB-1/T
The increase is A-1=1.28 times, which is an unexpectedly large advantage.

Claims (1)

[Claims] 1 In a pneumatic tire, the carbon content of the bead wire material is 0.75 to 0.90%, and the tensile strength is 220%.
~240? /mi, shear impact energy is 130 to 9
A pneumatic tire characterized in that it is reinforced with a bead wire having a diameter of /d or more.