JP2688522B2 - Pneumatic tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic tire capable of improving cut resistance without impairing other performances.

[Conventional technology]

Pneumatic radial tires, especially aircraft tires that operate at high speeds and heavy loads, have increased operating speeds and applied loads due to the recent increase in the size of aircraft and increase in flight speed, and therefore, when aircraft take off and land on the runway. In order to effectively mitigate the impact of the
%, Which means that it can withstand a large amount of cyclic deformation, and as the speed of an aircraft increases, the speed associated with takeoff and landing increases,
Therefore, it is desirable to endure high speed rotation under large load and large deformation, and to withstand taxi conditions in which large load acts for a relatively long time, although it is low speed when moving between runway and gate. Be done.

On the other hand, as such an aircraft tire, a cross-ply structure in which carcass cords are arranged so as to intersect each other is often used.

However, the tire of this structure has an excellent advantage that the lateral rigidity is large because the carcass cords cross at a large angle, but the rigidity of the tread portion is smaller than that of the radial tire having a strong belt. Because
There is also a drawback that the tread wear is rather large.

In addition, when taking off and landing, or when traveling between the runway and the gate, the tread portion is easily damaged by foreign substances that tend to be scattered on the road surface, and when damaged, the damage is relatively easy. The tread portion is impaired by reaching the surface of the inner layer and damaging the inner layer even by the foreign matter that has penetrated, impairing the durability. Therefore, it is also necessary to improve the resistance to damage to the tread portion, that is, the cut resistance.

Note that such damage to the inner layer or the like may make it difficult to retread the tire by replacing the tread rubber.

On the other hand, as aircraft tires, other than those having a cross-ply structure, so-called radial tires in which carcass cords are arranged substantially at right angles to the tire equator, radial tires having a semi-radial structure are being used, but compared with radial tires, As described above, in a tire having a cross-ply structure that is inferior in abrasion resistance and does not have a belt layer, it is important to improve the cut resistance in order to protect the carcass.

For radial tires, see, for example, JP-A-61-19680.
Japanese Patent Publication No. 4 proposes an aircraft tire in which a bunt layer is provided outside the belt layer.

Furthermore, JP-A-57-201704 proposes a tire that employs a band layer using a corrugated steel cord.

[Problems to be solved by the invention]

However, aircraft tires according to the former proposal are:
Although the band layer can improve the cut resistance to some extent and improve the in-plane bending stiffness, in this tire, since the organic fiber cord is adopted as the cord of the band layer, the cut resistance is improved. Cannot be improved sufficiently.

Further, in the latter, although the cord is corrugated, since it uses a steel cord, it is inferior in extensibility, and due to the large hoop effect, the inflation shape due to the internal pressure filling of the tire is distorted, and sometimes, The rib formed on the tread portion may meander. When a cord made of only steel is used in a cross-ply tire, the weight of the tire becomes large and the durability is reduced.

An object of the present invention is to provide a pneumatic tire capable of improving cut resistance, on the basis of adopting a cut protector using a composite cord.

The pneumatic tire of the present invention can be suitably used as a high-speed heavy-duty tire, particularly as an aircraft tire, and can also be used as a passenger car tire, a truck tire, and the like.

[Means for solving the problem]

The present invention, a plurality of bead cores are juxtaposed in the bead portion, the outer surface is tucked from the tread portion to the side wall portion, and the bead core of the bead portion is folded back and inclined with respect to the tire equator. A carcass composed of a plurality of carcass plies used, and a cut protector using a protection cord located outside the carcass and arranged at an angle of 0 degrees or more and 90 degrees or less with respect to the tire equator, and the protection. The cord is composed of a parent cord made of organic fiber, a steel wire inside which is spirally wound, and an outer steel wire which is wound outside the inner wire and in a spiral opposite to the inner wire. Is a pneumatic tire made of a composite cord wound with a metallic strand wire containing.

[Action]

The cut protector arranged outside the carcass prevents the damage from reaching the carcass when the outer rubber layer is damaged by foreign matter on the road surface. Further, as a protection cord of the cut protector, a composite cord in which a metallic cord is wound around a parent cord using organic fibers is used. As a result, the metal strands function as a protective body against foreign matter and prevent damage to the carcass. It also minimizes weight gain. Further, the protective cord, by using a parent cord made of an organic fiber, can impart an appropriate stretchability and prevent a rigidity step from occurring between the carcass and the tread rubber,
Damage and its spread can be prevented. Moreover, when the cut protector is arranged inside the tread portion and outside the carcass, the in-plane bending rigidity of the tread portion can be increased to some extent, and the cornering force can be improved.

〔Example〕

Hereinafter, one embodiment of the present invention, tire size 49 × 17 20/32
A description will be given using a PR aircraft bias tire as an example.

1 and 2, the aircraft bias tire 1 is
A toroidal shape including a bead portion 3 through which a pair of left and right beads cores 2 pass, a sidewall portion 4 which is continuous with the bead portion 3 and extends outward in the tire radial direction, and a tread portion 5 which joins between the outer ends of the sidewall portion 4. The bead core 2 includes a first bead core 2A, a second bead core 2B, and a third beat core 2C that are juxtaposed outward from the inner side in the tire axial direction.

Further, on the tire base 6, a carcass 7 composed of a carcass group G ... which is folded back from the tread portion 5 to the side wall portion 4 at the bead cores 2A, 2B, 2C of the bead portion 3 and a cut protector 9 are arranged. The cut protector 9 covers the outside of the carcass 7 in the range from the tread portion 5 to the side wall portion 4 to the bead portion 3, and the carcass protection ply 9A and the inside of the tread portion 5 and the carcass protection ply 9A.
And a tread protection ply 9B which is arranged on the outer surface in the radial direction via a retread rubber 10.

The carcass ply group G, as shown in detail in FIG.
Six carcass plies 11a, 11a located inside the tire wound around the first bead core 2A from the inside to the outside of the tire,
A first carcass ply group consisting of 11b ... and a second carcass ply group consisting of four carcass plies 11c ... wound around the bottom surface of the second bead core 2B from inside to outside. GB (shown by the solid line in FIG. 1), a third carcass ply group GC (first carcass ply group 11C) consisting of four carcass plies 11d wound around the bottom of the third bead core 2C from the inside to the outside.
(Indicated by a broken line in the figure), whereby the six carcass plies 11a ..., 11b ... of the first carcass ply group GA are included.
Of the four, the outer four carcass plies 11b ..., the carcass ply 11c of the second carcass ply group GB, and the carcass ply 11d of the third carcass ply group GC are the first, second, and third. The bead cores 2A, 2B, and 2C form folded-back portions GA1, GB2, and GC3 that are folded back outward in the radial direction.

Further, the two inner carcass plies 11a, 11a of the first carcass ply group GA are along the outer surface of the folded-back portion GC1 via the bottom portion GA2 passing through the bottom surfaces of the first to third bead cores 2A to 2C. A folded-back portion GA3 that is folded back radially outward is formed.

Furthermore, the first to third bead cores 2A to 2C are folded back to the first
~ Main body of the third carcass ply group GA ~ GC, and folding part
GA1 to GC1 are provided with a filler 12 surrounding each of the first to third bead cores 2A to 2C, and inside thereof, a bead apex 13 made of hard rubber and extending outward in the radial direction is formed ... By providing the, the rigidity of the bead portion 3 is enhanced.

As the bead apex 13, a hard rubber, for example, a dynamic elastic modulus (E ^* ) of 77 ° C using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho, initial strain 10%, amplitude 2.0%, frequency 5
200 kg / cm ^{2 to} 1500 kg / cm ² , preferably 900 kg measured at 0 Hz with a sample of 4 mm width × 30 mm length × 2 mm thickness
It is advisable to use a rubber of / cm ² or more.

In addition, a chainer 15 is arranged along the bead portion 3 to prevent abrasion damage to the rim.

The carcass protection ply 9A extends on the outer side of the carcass 7, that is, along the outer surface of the third carcass ply group GC, and extends along the tread portion 5, the side wall portion 4, and the bead portion 3.
Carcass plies 11a, 1 of the first carcass ply group GA
In this example, the main body 9A1 that covers the outer surface of the folded-back portion GA3 of 1a is provided with an extending portion 9A2 that extends below the bottom portion GA2 to the inside of the tire, and two plies 13a formed by using a protection cord 20. , 13b are included.

As described above, the tread protection ply 9B is arranged inside the tread portion 5 and outside the carcass protection ply 9A in the radial direction via the retread rubber 10, and one or more sheets using the protection cord 20 are used. It consists of a number of plies 13c and 13d, and a wide ply 13c is arranged inside. This tread protection ply 9B improves the cut resistance of the tread portion 5, reduces the occurrence of a rigidity step between the tread portion 5 and the rubber, and reduces the shear stress between them, thereby damaging the tread portion 5. , And the function of suppressing its expansion.

Therefore, the tread protection ply 9B is preferably arranged on the entire width of the tread portion 5. Further, the narrow ply 13c has at least 70 of the ground contact width S in the tire axial direction at which the outer surface of the tread portion 5 contacts the ground when the tire 1 is assembled to the regular rim and a regular internal pressure and a regular load are applied.
% Or more. In addition, it is preferable to set the full width of the tread portion 5 as described above in consideration of the maximum deformation during takeoff and landing.

Further, the cut protector 9 may be formed of one layer or a plurality of layers of three or more in addition to the case of using two layers of plies.

Next, as the protection cord 20, as shown in FIG. 3, a composite cord in which a metal cord 22 is wound around a parent cord 21 made of organic fiber is used. For the sub wire 22, steel having excellent strength is preferably used.

Parent code 21 is rayon, polyester, vinylon,
Aliphatic polyamides such as nylon 66, aromatic polyamides,
Flexibility and extensibility are enhanced by using monofilaments 21A made of organic fibers such as polyvinyl alcohol fibers and twisted cords made by twisting 21A. The parent cord 21 has a relatively small diameter of about 300d / 2 to 1350d / 3.

As the parent cord 21, in addition to a large diameter monofilament, a twisted cord made of a rope or a strand in which a plurality of monofilaments are twisted may be used.

As shown in FIG. 3, the slave wire 22 includes a steel wire 22b spirally wound around the parent cord 21 and a steel wire 22b outside and inside the steel wire 22b. It can be formed from a steel wire 22c outside the winding with a reverse spiral.

In the case where the parent cord 21 is a twisted cord, the steel strand 22b in the inside prevents the untwisting of the parent cord 21 by forming a spiral in a direction opposite to the direction of the twisted spiral.

Furthermore, the diameter of the steel strands 22b and 22c is about 0.05 to 0.3m.
If necessary, it is preferable to apply brass plating having a thickness of about 2 μm or more in order to improve rusting and compatibility with rubber.

Further, when the two steel wires 22b and 22c are used, the child wire 22 has a spiral pitch Pb of the steel wires 22b in the inner wire is about
0.3 to 1.2 mm, and the spiral pitch Pc of the outer steel wire 22c is about 1.0 to 2.0 mm, and the spiral pitch Pc of the outer steel wire 22c is larger than the spiral pitch Pb of the inner steel wire 22b. And

By setting the helical pitch Pb of the steel strands 22b within the above range, the flexibility of the protection cord 20 is maintained while protecting the parent cord 21 made of organic fibers. For this purpose, the minimum gap between the steel wires 22b, 22b wound around the spiral is set to a distance larger than 50% of the wire diameter in the above range. When the spiral pitch Pb is greater than 1.2 mm, the gap between the steel wires 22b, 22b inside becomes excessively large, and the function as the cut protectors 9A, 9B is deteriorated.

The outer steel wire 22c also enhances the protection function while maintaining the flexibility of the protection cord 20, and is preferably wound more loosely than the inner steel wire 22b. .

In FIG. 4, a steel wire 22b having a diameter of 0.15 mm is helically pitched at 0.88 mm in a Z-twist and a Z-twisted steel wire is attached to a parent cord 21 made of a 1260d / 2 S-twisted cord made of nylon 66. Helical pitch P with outer steel strand 22c of the same diameter
The elongation curves of the protection cords 20 each having a c of 1.39 mm and wound in an S-twist are illustrated by solid lines.

In addition, the elongation curve of the twisted cord A consisting of only 1260d / 2 nylon 66 cord is shown by a broken line in FIG.

As can be seen from the figure, the protection cord 20 having the steel strands 22b and 22c shows a larger elongation at the same load as compared to the twisted cord A having no steel strand. Further, it was found that the breaking load (kgf) of the protection cord 20 was reduced by about 20% as compared with the twisted cord A.

This is because the diameter of the parent cord 21 has been reduced in advance by winding the steel wires 22b and 22c.
It is considered that the length is reduced due to the spring back after the winding of 2c.

The decrease in the breaking strength is considered to be due to the notch effect due to the winding of the steel strands 22b and 22c. However, as the protection cord 20 in which the cut resistance is particularly important, such a decrease does not pose a problem.

This protection code 20 is 0 to 90 with respect to the tire equator CO.
The plies 13c and 13d of the tread protection ply 9B are formed by arranging the plies at an arbitrary inclination. This tread protection ply 9B has cut resistance as well as tread 5
When the plies 13c and 13d are arranged in a crossed arrangement, preferably in the range of 10 to 70 degrees, and more preferably in the range of 30 to 60 degrees when increasing the in-plane bending rigidity of the plies 13c and 13d. Tilt.

In addition, the protection cord 20 has 20 to 60
~ 60E / 5cm). When the number is less than 20, the cut resistance is inferior. When the number exceeds 60, the tire weight increases and the tire becomes expensive.

Therefore, the number is preferably about 30 to 50 per 5 cm.
Further, the protection cord 20 includes plies 13c and 13d formed by a cord winding method in which one or a plurality of cords are spirally wound at a small angle.
Can also be formed.

The inclination of the protection cord 20 of the plies 13a and 13b of the carcass protection ply 9A is determined according to the carcass cord of the carcass 7.

The carcass cords of the first, second, and third carcass ply groups GA to GC are inclined in the range of 20 to 50 degrees, preferably 30 to 45 degrees with respect to the tire equator. Moreover, the first to third carcass ply groups GA to GC arranged in order from the inside to the outside of the tire
The cord angle of the carcass cord is gradually reduced.

For example, the cord angle of the first carcass ply group GA is
25 to 50 degrees, preferably 30 to 45 degrees, 40 degrees in this example, and the first and second carcass ply groups GB and GC
1 to 5 in comparison with the cord angle of the carcass ply group GA of
The code angle is sequentially reduced in angular steps of degrees, preferably about 2 degrees. That is, when the chord angle of the first carcass ply group GA is 40 degrees as described above, the chord angle of the second carcass ply group GC is 38 degrees and the chord angle of the third carcass ply group GC is 36 degrees. Set to a degree.

Moreover, in the carcass plies 11a to 11d in the carcass ply groups GA to GC, the carcass cords are arranged so as to intersect each other. By reducing the cord angle from the inner side to the outer side in this manner, the rigidity of the ply is increased from the inner side to the outer side, and a desired predetermined inflated shape can be obtained.

The protection cord 20 of the carcass protection ply 9A can be set to 0 to 90 degrees, preferably 10 to 70 degrees with respect to the tire equator CO, but from the above-mentioned viewpoint of the carcass 7, the ply of the carcass protection ply 9A can be obtained. The inclination of the protection cord 20 of 13a and 13b is preferably set to be smaller, for example, about 34 degrees.

In addition, the said 1st-3rd carcass ply group GA-GC said folding | returning part GA1-GC1 makes the height large one by one toward an outward direction, and especially the folding | returning part GC1 of 3rd carcass ply group GC is the maximum of a tire. It is terminated near the width position.

Furthermore, in the present embodiment, the inside of the tread portion 5 and between the second inner carcass ply group GB and the third inner carcass ply group GC and between the outer carcass ply group GD and the third inner carcass ply group GC are Two first and second cap ply layers C1 and C2 are arranged between them.

The cap ply layers C1 and C2 each include two cap ply layers 16a, 16a, 16b and 16b, and the cap cord of the first cap fly layer C1 is located at the tire equator.
At an angle of 36 degrees, the cap cords of the second cap ply layer are oriented at 34 degrees, intersecting each other and each adjacent carcass cord.

In the first and second cap ply layers C1 and C2, at least one of the cap ply layers 16a and 16b is set to about 110 to 130% of the width S of the ground contact surface of the tire in the tire axial direction. From this, the outer ends of the cap ply layers 16a and 16b are
It is discontinuous in the radial direction of the bead portion, which makes it smaller than the carcass plies 11a to 11d wound around the bead core 2 and effectively reinforces the tread portion 5 on which a large load acts in use. Further, by disposing the cap ply layer C between the carcass ply groups G, the stress due to the contraction due to the thermal action at the time of vulcanization of the cap ply layer C is carried by the carcass ply group G located inside thereof. sell.

The carcass plies 11a to 11d, the cap ply layer C1,
For each C2 carcass cord and cap cord, polyethylene fiber, polyurethane fiber, cellulose fiber,
Organic fibers such as cellulose ester fibers and aromatic polyamide fibers can be used, and aliphatic polyamide fibers such as nylon 66 can be preferably used.

In addition, carcass cords and cap cords are made of relatively soft rubber, such as 300% modulus of 80-160kg / c.
m ^2, preferably by embedding in the topping rubber in the range of 90~110kg / cm ^2, the plies 11 a to 11 e, 16a, 16b
To form

The retread rubber 10 extends over the entire width on the radially inner side of the breaker 10 and has a thickness of 2.0 mm or more.

This prevents the carcass 7 from being damaged when the tread rubber is removed during tire rehabilitation. By using a rubber having a hardness lower than that of the tread rubber as the retread rubber 10, the carcass 7 can be easily removed and the carcass 7 can be easily removed. Prevent damage. Note that the carcass 7 may be protected by using rubber that is equivalent to or harder than the tread rubber.

Further, the tire 1 may use either one of the carcass protection ply 9A and the tread protection ply 9B as the cut protector 9 or one of them.

〔Concrete example〕

Aircraft bias tires with tire sizes of 49 × 17 32 PR were prototyped according to the specifications shown in FIG. 1 and Table 1 (note that in Table 1, the codes shown by the symbols in Table 2 are used). In addition to filling the normal internal pressure, US Civil Aviation Bureau standard TS
Taxi mileage based on O-C62c The durability was tested based on the solution test. After the test, those that withstood takeoff at 200% load are indicated by a circle (the number of times indicates the number of times before destruction in the test).

Further, the cornering force was measured using a flat belt type indoor tester, and is shown as an index with Comparative Example 1 being 100. A higher value indicates a better result. The weight is also shown by an index with Comparative Example 1 being 100.

Cut resistance is 5mm in height on the drum as shown in Fig. 5.
Wedge pieces a having a tip radius of 0.5R are scattered and rotated at a load of 150%, and the time until the tire breaks is shown by an index notation in which Comparative Example 1 is 100. The larger the index, the better the result. An index of 120 or more is a passing criterion.

〔The invention's effect〕

Thus, the tire of the present invention can improve the cut resistance without impairing other properties.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view illustrating a ply structure, FIG. 3 is a diagram illustrating a protection cord, and FIG. 4 illustrates characteristics of the protection cord. FIG. 5 is a perspective view illustrating a drum for a cut resistance test. 2, 2A, 2B, 2C ... bead core, 3 ... bead part, 4 ...
… Sidewall part, 5 …… Tread part, 7 …… Carcass, 10 …… Retread rubber, 11a, 11b, 11c, 11d …… Carcass ply, 20 …… Protection code, 21 …… Parent code, 22
...... Child wire, 22b …… Steel wire inside, 22c …… Steel wire outside. C, C1, C2 ... cap ply layer, G ... carcass ply group, GA ... first inner carcass ply group, GB ... second carcass ply group, GC ... third inner carcass ply group,
GD: Outer carcass plies.

Continuation of the front page (56) Reference JP-A-51-106906 (JP, A) JP-A-61-196804 (JP, A) JP-A-59-15587 (JP, A) JP-A-57-143535 (JP , A) Actually open 58-180705 (JP, U) Actually open 56-53798 (JP, U)

Claims (5)

(57) [Claims] 1. A carcass cord of organic fibers in which a plurality of bead cores are juxtaposed in a bead portion, and a tread portion whose outer surface is in contact with a side wall portion is folded back at the bead core of the bead portion and inclined with respect to the tire equator. A carcass consisting of a plurality of carcass plies using the above, and a cut protector using a protection cord located outside the carcass and arranged at an angle of 0 degree or more and 90 degrees or less with respect to the tire equator, and The protective cord consists of an inner steel wire that is spirally wrapped around a parent cord that uses organic fibers, and an outer steel wire that is wound outside the inner wire and in the opposite direction to the inner wire. Pneumatic tire consisting of a composite cord wound with a metallic strand wire containing. 2. The cut protector is formed of the protection cord, is located inside the tread portion, and when the tire is assembled into a rim, and has a normal inner pressure and a normal load, a ground contact width of the outer surface of the tread portion in the tire axial direction. A pneumatic tire according to claim 1, characterized in that it comprises a tread protection ply with a width of more than 70%. 3. The cut protector has a carcass protection ply which is made of a protective cord and covers the outside of the carcass in a range from the tread portion to the sidewall portion to the bead portion. Pneumatic tire. 4. The carcass protection ply, which comprises a protection cord and covers the outside of the carcass in the range from the tread portion to the sidewall portion to the bead portion, and the carcass protection ply radially outwardly of the carcass protection ply. A tread protection ply having a width that exceeds 70% of the ground contact width in the tire axial direction on the outer surface of the tread portion when the tire is rim-assembled and the tire is rim-assembled and the regular internal pressure and the regular load are applied. The pneumatic tire according to claim 1. 5. The pneumatic tire according to claim 1, wherein the outer steel wire has a spiral pitch larger than that of the inner steel wire.