JPS5977906A - Radial tire for heavy vehicle - Google Patents

Abstract

PURPOSE:To prevent the separation of plies of a belt layer by a method in which a triangle belt layer is made up of 4 plies with steel cords arranged at given angles for each, and a high-elastic cord protective layer is interposed between both ends of the second and third plies. CONSTITUTION:A belt layer 10 is made up by orderly laminating the first - the fourth plies 1-14 wherein steel cords are each arranged at 50-70 deg., 10-30 deg., -10--30 deg., and -10--30 deg. to the circumferential direction of tire and the first ply 11 in proximity to carcass. A high-elastic cord protective layer 15 almost in parallel with the circumferential direction is interposed with a width W0 of 5-100mm. on both ends of the second and third plies 12 and 13. The distance L between the outside end 15a of the layer 15 and the end 12a of the second ply is set up to about 10mm. or less, and the width W2 of the second ply is set to 100-130% of that W3 of the third ply and the width W3 of the third ply is made wider than that W1 of the first ply. The separation of the plies can thus be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radial tire for a heavy vehicle, particularly to an improvement in a radial tire for a heavy vehicle having a belt layer having a triangular structure.

In general, the structure of a radial tire for heavy vehicles is as shown in Figure 1, where both ends are folded back around a heat core (1).
At least one toroidal carcass ply (2) is arranged with its cords in the lateral or semiral direction, the heat part is reinforced with a heat filler (3), and a tread (4) is arranged in the crown part (E). A commonly used heald layer (9) is formed by stacking four plies (5) +6+ +7) (8) of steel coat on the underside of the tread (4) in the circumferential direction. It's the first one. Two types of configurations of the bell h m +9) are adopted as shown in Table 1. Here, the structure of type A is as shown in FIG. This is a so-called trianocle structure in which the bell layers are crossed with each other in the circumferential direction to increase the circumferential rigidity of the bell layer. In such a structure, the second ply (6) and the third ply (7) intersect at a dog-shaped angle, resulting in a shear strain cylinder before and after applying internal pressure or load to the tire. In other words, as shown in Fig. 3, as the load is applied, the second ply (6) and the third ply (7) move in mutually opposite directions in accordance with the coat angle, causing shear strain at the shear angle (θ). . As a result, the second ply (6) and the third ply (
7), especially at both end portions (6a) and (7a), combined with the difference in rigidity at that portion, peeling between the plies occurs.

Therefore, the inventor conducted repeated research to reduce the shear strain between the second ply and the third ply while maintaining the in-plane bending rigidity, which is a feature of the conventional triangular structure.
It has been found that the shear strain between both plies can be reduced and alleviated by interposing a protective layer containing highly elastic cords substantially parallel to the circumferential direction between both ends of the ply and both ends of the third ply,
This has led to the present invention. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to effectively prevent separation between plies while maintaining the rigidity of the bell 1 layer of a Lareal tire for heavy vehicles having a heald layer having a so-called triangle structure.

The present invention provides a runal tire having a 1-let part in the crown part of the runal ply carcass and a belt layer disposed between the tread part and the l-let part and the carcass, the belt layer having a steel cord around the tire circumference. 50 in the direction
A first ply placed adjacent to the carcass at an angle of 0.8° to 70° and a steel coat placed adjacent to the carcass in the circumferential direction of the tire.
The second ply disposed adjacent to the upper side of the first ply at an angle of ~30'' and the steel coat at an angle of -10'' to -30° in the circumferential direction of the tire. A fourth ply is arranged adjacent to the upper side of the third ply at an angle of 10° to 30° in the tire circumferential direction, and a steel coat is formed between both ends of the second ply and the third ply. This is a run-arc tire for a heavy vehicle, characterized in that a protective layer including a highly elastic cord substantially parallel to the circumferential direction is interposed between both ends of the ply.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 4 shows a schematic plan view of the bell i layer of the present invention.

In the figure, the bell is composed of four layers, from the first ply to the fourth ply (10) +, t, and the first ply (11
), second ply (12), third ply (18) and fourth ply
Each ply (14) is composed of steel coat. Then both ends of the second ply (12) and the third ply (1
A protective layer (15) is interposed between both ends of 3).

Here, the protective layer (15) is constructed by embedding highly elastic cords substantially parallel to the circumferential direction in rubber, and its width (Wo) is 5 to 5.
100 mm, preferably in the range of 10 to 50 mIn;
Further, the outer end (15a) is connected to the second ply end (12a) or +3
The distance between the third ply end (1
8a) or beyond the third ply end (18a)
) is placed inside. However, in the present invention, a protective layer made of a cord having an intermediate cord angle between the cord angles of the second ply (12) and the third ply (13), that is, approximately parallel to the circumferential direction of the tire, is interposed between the two. Therefore, the shear strain caused by the cord angle can be reduced by almost half. In addition, the width (Wo) of the protective layer was specified as described above; if it is less than 5 mm, it is not effective in alleviating strain at the ends of the ply;
If it exceeds the 00m+n range, the strain relaxation effect will not decrease, but material costs and manufacturing costs will increase, which is not preferable.

Furthermore, the bed l1l (15) is usually wrapped once in the circumferential direction on the upper side of the second ply, and the overlap at both ends is 0 to 100 mm.
However, if the bonding strength at both ends is low, it may be wrapped twice.

The high elastic cord constituting the protective layer is a steel cord or an aromatic polyamide fiber cord. When a steel cord is used as a high-modulus cord, it should be the same as or smaller in diameter than the steel cord in the belt layer, but in order to prevent the formation of new rigid faults at both ends of the protective layer itself, the smaller diameter is used. It is preferable to use steel cord. For example, the twisted structure is 1 x 4 or 1 x 5, and the diameter of the steel filaments constituting the cord is usually 0.15 to 0.40 mm, preferably 0.2 to 0.40 mm.
It is 25 mm. Also, the number of steel cords embedded in the rubber is 20 to 60 15cm, preferably 30.
~40 pieces/5 cm.

Next, the aromatic polyamide fiber cord used has a strength of 13 g/d or more and an initial modulus of 170 kg/0012 or more. In addition, the twist coefficient (NT) of the aromatic polyamide fiber cord expressed by the following formula is usually in the range of 0.20 to 0.055 for both twist and first twist, particularly preferably 0.
．． The first twist is in the range of 30 to 0.42 and the final twist is 120 to 180.
Set to a range of %.

N T = N As a result, strength and modulus decrease, and the ply becomes curled, impairing molding workability. On the other hand, if it is less than 020, it is not preferable because it impairs the cohesiveness and fatigue resistance. Further, the embedded rubber of the protective layer is a comb having a modulus comparable to or slightly smaller than that of the embedded rubber of the adjacent belt layer, for example, a 300% modulus of 120 to 280.
kg/cm2. 180 ” 280 kg especially when using aromatic polyamide fiber cord
By using a material having the same molecular strength as the steel cord ply of the belt layer in the range of /cm2, the effect of alleviating shear strain can be enhanced. Modulus is 120
If the weight is less than kg/am2, the effect of the arrangement of the protective layer, that is, the prevention of inter-ply peeling, is not sufficiently effective.

Next, the cord angle of the first ply (11) is arranged at an angle of 50° to 70° with respect to the tire circumferential direction. This is to reduce the cord angle between carcass plies that have cord angles close to this, reduce ply distortion between them, and further increase the in-plane bending rigidity of the bell 1 by forming a triangular structure with other plies. be.

Also, the width (W2) of the second ply (12) is different from the width (W2) of the second ply (12).
3) is set within a range of 100 to 130% of the width (W3) and within 120% of the tread width. Here, if it exceeds 120% of the tread width, a new starting point of stress concentration will occur at the end of the second ply.

Next, the eighth ply (13) is usually the first ply (11) (
The cord angle is formed to be wider than or substantially the same as the cord of the second ply (12) and intersects with the cord of the second ply (12) at an angle of 110 in the tire circumferential direction.
°~-30°. Here, a negative angle means that the cord is inclined in the opposite direction to the cord of the second ply.

Further, the fourth ply (14) is arranged above the third ply (13) and has a width of 50 to 90% of the width of the first ply.

FIG. 6 shows another embodiment of the present invention. Here, the first ply is divided into two plies (16) (1
7). In this structure, the circumferential rigidity of a part of the crown center is weakened to increase the gloss of the outer periphery, while the change in the outer diameter of a part of the shoulder is suppressed, thereby reducing shear strain between the second and third plies. It has the effect of Here, the ply interval (W6) of the first briar is in the range of 5% to 40%, preferably 7% to 20% of the total ply width (W2).

As described above, the present invention provides a protective layer of a high elasticity coat having a coat angle between the above two on both ends of the heald layer of a steel lareal tire, particularly the second and third plies of the trianocle structure. The resulting shear strain can be effectively suppressed, and the heald layer laterality, which is an original feature of the triangular structure, can be maintained.

EXAMPLE Tires with Kuiyasaisu 10.0OR2014PR steel radial carcass cord were manufactured according to various specifications shown in Table 1, and their performance was evaluated. The results are shown in the same table. The basic structure of the prototype tire is the first one, excluding the belt layer.
As shown in the figure.

Crack damage at the end of the belt layer is on a drum diameter of 1593 mm, tire internal pressure 8.0 kgf/cd, load 4000 kgf
The vehicle was run at a speed of 50 km/h, and the distance traveled until cracks appeared at the end of the heald was measured. From Table 1, it can be seen that all of the tires of the present invention have significantly improved mileage over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional tire, FIG. 2 is an enlarged front view of its heald layer, FIG. 3 is a partial sectional view of a belt layer, and FIG. 4 is a schematic plan view of the heald layer of the present invention. is a schematic cross-sectional view thereof, and FIG. 6 is a schematic cross-sectional view of a heald layer according to another embodiment of the present invention. 10. Belt layer 13. 3rd ply 11 1st ply 14. 4th ply 12 2nd ply
15 Mamoru Layer Patent Applicant Sumitomo Rubber Industries Co., Ltd. Attorney Yoshihira Nakamura Figure 1 Figure 2 Figure 4 Figure 3 Figure 5 Figure 6

Claims (6)

[Claims] (1) In a radial tire that has a tread part in the crown part of a Lareal ply car cane and a belt layer installed between the tread part and the carcass, the heald layer is formed by applying a steel coat at an angle of 50° to 70° in the tire circumferential direction. a first ply disposed adjacent to the carcass; a second ply disposed adjacent to the upper side of the first ply with a steel cord at an angle of 10° to 30° in the tire circumferential direction; Steel coat at -10° to -30° in the tire circumferential direction
The third ply, which is disposed adjacent to the upper side of the second ply, and the steel cord are connected at an angle of 110 mm in the tire circumferential direction.
The fourth ply is disposed adjacent to the upper side of the third ply at an angle of between -30 degrees, and the circumferential direction is between both ends of the second ply and both ends of the third ply. A radial tire for a heavy vehicle, characterized in that a protective layer made of substantially parallel high-elastic cores is interposed therebetween. (2) The radial tire according to claim 1, wherein the protective layer is composed of one layer. (3) The radial tire according to claim 1, wherein the ply width (Wl) of the first ply is smaller than the ply width (W2) of the second ply. (4) The radial tire according to claim 1, wherein the first ply is a single ply or a two-part ply. (5) The high elasticity cord of Hoi II is a cord thinner than the steel cord of the belt layer.
Radial tires listed in section. (6) The radial tire according to claim 1, wherein the high modulus cord is a steel cord or an aromatic polyamide fiber cord.