JPH0431107A - Radial tire - Google Patents

Abstract

PURPOSE:To To concurrently improve the uniformity of a tire, enhance the durability at high speed and reduce the manufacturing cost by dividing a cap ply covering the whole width of belts into more than 3 portions in the axial direction of the tire, shifting the curled end sections of the cap ply portions in the circumferential direction of the tire, and thereby make each elongation of the cap ply portions different at the time of constant loading. CONSTITUTION:In a tread section 1, a belt is made up out of 2 belt plies 20 and 22 while they are winded up onto a carcass 10. And a cap ply 30 in which organic fiber cords are embedded, is formed in such a way that the whole width of both of the belt plies 20 and 22 is covered. In this case, the cap ply 30 is divided into 3 portions 32, 36 and 38 in the axial direction of a tire. In addition, the curled end sections of both side peripheral cap ply portions 36 and 38 are respectively disposed at places where they are mutually shifted roughly by 120 deg. to the opposite sides in the circumferential direction of the tire from the curled end section 33 of the central cap ply portion 32. Furthermore, the elongation of the organic fiber cords 37 and 39 of the side peripheral cap ply portions 36 and 38 at the time of constant loading is made smaller than that of the organic fiber cords 34 of the central cap ply portion 32.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves winding a belt around the carcass in the tire circumferential direction, and further wrapping a cap ply having an organic fiber cord so as to cover the entire width of the heald. / Altaiya 1 related.

[Prior art and problems to be solved by the invention] In the conventional manufacturing process of radial tires, in order to form a cap ply, a large number of organic fiber cords of the same thickness are arranged substantially parallel and uniformly in a band-shaped rubber member. I was using what I had available. Usually, this band-shaped rubber member is wider than the belt wound on the carcass, and is wound so as to cover the entire width of the belt, and the end portion of the band is overlapped with itself by a width of several tens of millimeters. In the cap ply thus formed, the organic fiber cords are arranged substantially parallel to each other in the circumferential direction of the tire. However, since the joint portion is localized in the circumferential direction of the tire, this causes unevenness in thickness and thus unevenness in rigidity. As a result, there was a problem with tire uniformity, especially the radial force variation (RF V). In addition, since the belt side edges cannot be sufficiently pushed in with the cap ply, the belt side edges rise due to centrifugal force during high-speed running, which tends to cause separation.

Therefore, a narrow band-shaped rubber member made of aligned organic fiber cords is wound spirally around a belt to form a cap ply.

In this case, although it is possible to minimize the negative impact on the winding end or tire uniformity, it not only requires special equipment for spiral winding, but also requires special equipment for spiral winding.
There was a problem with a significant increase in manufacturing man-hours. For this,
The cost of manufacturing tires will increase significantly.

In addition, if the cap ply is simply divided in the tire axial direction and the winding ends of adjacent cap ply portions are shifted from each other in the tire circumferential direction, the belt side edges will not be pushed in sufficiently, resulting in It is considered that the occurrence of separation cannot be sufficiently suppressed.

The present invention has been made in view of the above points, and provides a radial tire that simultaneously achieves improved tire uniformity, lower manufacturing costs, and improved high-speed durability by improving the structure of the cap ply. The purpose is to

[Means for Solving the Problems] The radial tire according to the present invention has a belt wrapped around the carcass in the tire circumferential direction, and a cap ply wrapped around the belt so as to cover the entire width of the belt. The fiber cords are arranged substantially parallel to each other in the circumferential direction of the tire, and the cap ply is divided into three or more parts in the axial direction of the tire, and each winding end of the adjacent can/knob ply part is arranged substantially parallel to each other in the circumferential direction of the tire. It's worn out,
The elongation of the organic fiber cord in the side edge cap ply portion under constant load is smaller than that in the center cap ply portion.

The density of the organic fiber cords may be made different between the divided central part and the side edge parts of the cap ply. In this case, the cord driving density in the side edge canknob ply portions is higher than that in the central gap ply portions.

[Function] In the runal tire according to the present invention, the camp ply on the belt is divided into three or more parts in the tire axial direction,
Moreover, since the winding ends of the adjacent cap ply portions rub against each other in the tire circumferential direction, the joint portions of the camp ply are dispersed in the tire circumferential direction. It is easy to wrap each cap ply part.

In addition, the elongation of the organic fiber coating in the side edge cap ply portion under a constant load is made smaller than that in the center cap ply portion, or the cord implantation density in the side edge cap ply portion is made higher than that in the center cap ply portion. This increases the rigidity of the side edge cap ply portion, allowing the side edge cap ply portion to firmly hold down the easily movable side edge of the heald. On the other hand, the rigidity of the central cap ply portion becomes relatively low, resulting in poor ride comfort.

[Example] FIG. 1 is a partially cutaway oblique view of a radial tire according to an example of the present invention. Tire size is 185/70R14
It is 87H.

The carcass 10 extends from the tread portion 1 through both site portions 2 to the left and right bead portions 3, and is folded back to the outside with the beet core 12 and the beet filler 14 rolled up. carcass 10
The cord 11 inside extends approximately perpendicularly to the tire circumferential direction.

In the tread portion 1, two belt braces 20 and 22 are wound around the carcass IO in the circumferential direction of the tire to form a belt. In each belt ply 20, 22, a large number of steel cords 21, 23 are embedded substantially parallel to each other and arranged at an angle of about 30° to the tire circumferential direction. Each cord 21°23 is made by concentrically twisting five steel wires each having a diameter of 0.25 mm (IX5
XO.

25). However, the steel cords 21 and 23 intersect between the first belt ply 20 on the inside and the second belt ply 22 on the outside.

Furthermore, a cap ply 30 in which an organic fiber cord is embedded is formed so as to cover the entire width of both belt plies 20 and 22. This cap ply 30 is divided into three parts 32, 36, and 38 in the tire axial direction. The central cap ply portion 32 is made of a thin organic fiber cord 34 made of 6.6 nylon with a thickness of 840 d/2 (elongation at a load of 4.5 kgf or 9%) in the longitudinal direction of a band-shaped rubber member with a width C. ) are arranged substantially parallel to each other and uniformly at a density of 21 pieces per 2.5 cm, and are wound twice on the second belt ply 22. Tatashi,
The winding end portion 33 is cut diagonally as shown. The left and right side edge cap ply parts 36 and 38 adjacent to the center cap ply part 32 are each made of a thick organic fiber cord 37 made of 6.6 nylon and having a thickness of 1260 d/2 in the longitudinal direction of the band-shaped rubber member having a width S. .39 (Load 4.
The elongation at 5kgf is 6.6%. ) is still 2゜5
It is formed by wrapping two heald plies, which are arranged substantially parallel and uniformly at a density of 21 per cm, twice so as to cover the edges of both heald plies 20 and 21.

The winding ends of the side edge cap ply portions 36 and 38 are similarly cut diagonally, and these winding ends are approximately 120° in opposite directions in the tire circumferential direction from the winding end 33 of the center cap ply portion 32. They are located in different places. However, only the winding end portion 33 of the central cap ply portion is shown in the drawing.

As described above, the organic fiber cords 36, 37, 39 in any part of the cap ply 30 are arranged substantially parallel to each other in the tire circumferential direction.

However, the elongation of the organic fiber cords 37 and 39 of the side edge cap ply portions 36 and 38 under a constant load is smaller than that of the organic fiber cords 34 of the central camp ply portion 32. Therefore, the side edge cap ply portion 3L3
8 has increased rigidity, and even when driving at high speed, both heald ply 2
The easily movable side edges of 0.22 can be firmly held down.

The elongation of the organic fiber cords 3739 of the side edge cap ply portions 36 and 38 under a constant load may be kept to less than 85% of that of the six-machine fiber cords 34 of the center cap ply portion 32.

Further, since the cap ply 30 is divided in the tire axial direction, and the winding ends of adjacent cap ply portions are shifted from each other in the tire circumferential direction, the cap ply 30
The joints are dispersed in the circumferential direction of the tire, improving tire uniformity. In addition, each cap ply portion 32
．． Since the winding work of 36.38 is easy, manufacturing costs can be reduced compared to the case of spiral winding.

FIGS. 2 and 3 are end views showing a helt ply 1' and a cap ply of a radial tire according to another embodiment of the present invention. However, the cords in the heald plies 20 and 22 are not shown.

Tire size is the same as above, 185/70R]
487H.

When using fiber cords 34, 37, and 39 of the same thickness for the three-divided portions 32, 36, and 38 of the gap ply 30, the side edge cap ply portion 3 is used as shown in FIG.
6.38 cord driving density in central cap ply part 3
Make it higher than 2. In the example shown in FIG. 2, the cap ply 30
How many machine fiber cords inside are 8 as 34, 37, 39
A 6.6 nylon cord with a thickness of 40d/2 is used, and the cord density of the central cap ply portion 32 is 2.5c.
21 pieces per m, side edge cap ply part 36.3
8, the cord implantation density is 25 cords per 2.5 cm. Other points, such as the fact that the camp ply 30 has a two-layer structure, are the same as in the case of FIG. 1.

As shown in FIG. 3, both the thickness and batting density of the organic fiber cords may differ between the central cap ply portion 32 and the side cap ply portions 36,38. In the example shown in FIG. 3, the central cap ply portion 32 has an 840 d
Thin organic fiber cord 3 made of 6.6 nylon with a thickness of
4 at a low density of 21 pieces per 2.5cm, while 1260d/1260d /
Thick organic fiber cords made of 6.6 nylon with a thickness of 37.39 mm are implanted at a high density of 28 cords per 2.5 cm. Other points, such as the fact that the cap ply 30 has a two-layer structure, are the same as in the case of FIG.

In both of the cases shown in FIGS. 2 and 3, the side edge cap ply portions 36, 38 have increased rigidity, so that the easily movable side edges of the belt ply 20, 22 can be firmly held down.

For comparison with the three types of radial tires according to the embodiments of the present invention described above, 6.6
It is a belt-shaped comb member in which nylon cords are evenly implanted at a density of 21 cords per 2.5 cm, and both belt plies are 20,
Place one wider than 22 on both belt plies 20.22.
A radial tire with a conventional structure in which a cap ply was formed by heavy wrapping was manufactured in the same size as the example.

The structure and materials of the carcass 10 and both belt plies 20, 22 are the same as in the example embodiment. If the RFV size of this comparative example tire is 100, then the RFV size is reduced to 80 in each of the examples. This demonstrated the effect of improving tire uniformity according to the present invention.

On the other hand, as a result of a high-speed durability test in accordance with the provisions of the European safety standard ECE30, in the case of the comparative tire, the
Separation occurred at the side edges of the belt after running for 19 minutes at a speed of m/h. In contrast, Fig. 1 (Example 1
), in the case of 10 under a speed of 230 km / h
Belt separation occurred after 1 minute of running.

In the case of Fig. 2 (Example 2), 220 km/h
3 (Example 3)
), separation occurred only after 18 minutes of driving at a speed of 240 km/h. This also demonstrated the effect of the present invention on improving high-speed durability.

Note that the number of divisions of the gap ply 30 may be three or more. However, the upper limit of the number of divisions is determined as appropriate from the viewpoint of ease of manufacture. The number of layers in each cap ply portion may be one or more. Further, the material of the organic fiber cord in each gap ply portion is not limited to the above-mentioned 6.6 nylon. It is also possible to use organic fibers such as polyester cord. Furthermore, the thickness and implant density of the organic fiber cords 34, 37, and 39 are merely examples, and are not limited thereto.

[Effects of the Invention] As explained above, in the radial tire according to the present invention, a heald is wound around the carcass in the tire circumferential direction, and a cap ply is further wound around the belt so as to cover the entire width of the belt. The organic fiber cords inside are arranged substantially upwardly and parallelly in the tire circumferential direction, and the cap ply is divided into three or more parts in the tire axial direction, and each winding end of the adjacent cap ply part is connected to the tire circumference. Because they rub against each other in the direction, tire uniformity can be improved while eliminating increased manufacturing costs, unlike in the case of conventional spiral winding. Moreover, the elongation of the fiber cords in the side edge cap ply portions at a constant load is made smaller than that in the center cap ply portion, or the cord driving density in the side edge cap ply portions is made higher than that in the center cap ply portion. This increases the rigidity of the side edge cap ply, allowing the side edge cap ply to firmly hold down the heald side edge, which tends to move easily during high-speed driving. That is, according to the present invention, it is possible to provide a radial tire that simultaneously achieves improved tire uniformity, lower manufacturing costs, and improved high-speed durability. Furthermore, the rigidity of the central cap ply portion is relatively low, improving riding comfort.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a radial tire according to an embodiment of the present invention; FIG. 2 is an end view showing a belt ply and a cap ply of a radial tire according to another embodiment of the present invention; FIG. 3 is a diagram similar to the previous one of a radial tire according to still another embodiment of the present invention. Explanation of symbols■...Tresoto part, 2...Side part, Butt part...Bead part, 10...Carcass, 20.22...Belt ply, 30...Cap ply, 32...Central cap ply Part, 33... Winding end of central cap ply part, 34... Organic fiber cord of central cap ply part, 3638... Side edge cap ply part, 37.
39...Organic fiber cord of side edge cap ply part. Patent applicant: Toyo Tire & Rubber Industries Co., Ltd.゛-(Representative Patent Attorney Tsuta 1) Shoko 1---and others 1
Name 2-1 Figure 3

Claims (1)

[Claims] 1. Wrap a belt around the carcass in the tire circumferential direction, and further wrap a cap ply to cover the entire width of the belt,
A radial tire in which the organic fiber cords in the cap ply are arranged substantially parallel to each other in the tire circumferential direction, the cap ply being divided into three or more parts in the tire axial direction, and each winding end of the adjacent cap ply part are offset from each other in the circumferential direction of the tire, and the elongation of the organic fiber cord in the side edge cap ply part under a constant load is smaller than that of the center cap ply part. 2. Wrap a belt around the carcass in the circumferential direction of the tire, and then wrap a cap ply to cover the entire width of the belt.
A radial tire in which the organic fiber cords in the cap ply are arranged substantially parallel to each other in the tire circumferential direction, the cap ply being divided into three or more parts in the tire axial direction, and each winding end of the adjacent cap ply part A radial tire in which the organic fiber cords are offset from each other in the circumferential direction of the tire, and the density of the organic fiber cords in the side edge cap ply parts is higher than in the center cap ply part.