WO2009113583A1

WO2009113583A1 - Radial tire for vehicle and method for manufacturing the same

Info

Publication number: WO2009113583A1
Application number: PCT/JP2009/054679
Authority: WO
Inventors: 武穂高; 哲也溝根; 孝行山本
Original assignee: 本田技研工業株式会社
Priority date: 2008-03-12
Filing date: 2009-03-11
Publication date: 2009-09-17

Abstract

Disclosed is a radial tire for a vehicle (1) in which a reinforcing layer (11) produced by winding an organic fiber cord into a helical shape in the circumferential direction of the tire is formed in a belt layer (10). The process of forming the reinforcing layer (11) comprises either winding two ribbons (12) containing an organic fiber cord around the circumferential surface (13a) of the tire carcass (13) from both ends in the width direction towards the center, or winding two ribbons (12) around the circumferential surface (13a) of the tire carcass (13) from the center in the width direction towards both ends.

Description

Radial tire for vehicle and manufacturing method thereof

The present invention relates to a radial tire for a vehicle and a manufacturing method thereof.

Recent automobiles tend to be equipped with radial tires excellent in handling stability and durability at high speeds. In this radial tire, two belt layers in which belt cords are inclined in opposite directions with respect to the tire circumferential direction are laminated, and this is disposed outside the carcass layer of the tread portion. The laminated belt layer has rigidity in the circumferential direction and the width direction, and the carcass layer is tightened by the effect to maintain the tire shape. Furthermore, when a reinforcing layer is provided outside the belt layer, the rigidity of the tread portion is improved and the high-speed durability is further improved. When forming the reinforcing layer, in the green tire molding process, as shown in FIG. 9, the carcass layer and the belt layer are inflated with a bladder to hold the tire skeleton 100, and in this state, an organic fiber is formed on the peripheral surface of the tire skeleton 100. A strip 101 including a cord is wound (see Non-Patent Document 1).
"Basics and Practice of Automobile Tires" (page 15), edited by Bridgestone Co., Ltd. Sankaido

That is, the band material 101 is wound around the circumferential surface of the tire frame 100 from one end to the other end. Conventionally, organic fiber cords with high elongation (for example, nylon) were used, so when green tires were inflated in the subsequent vulcanization process, the organic fiber cords were stretched to correct the tightening imbalance and It did not appear as a bug. However, when organic fiber cords with low elongation (for example, aromatic polyamide fibers) are used, the tightening imbalance in the vulcanization process is hardly corrected, and therefore the rubber flow is uneven in the vulcanization process. And conicity is deteriorated due to a decrease in uniformity accuracy.

In view of such circumstances, an object of the present invention is to provide a radial tire for a vehicle and a method of manufacturing the same, in which the conicity is not deteriorated even when an organic fiber cord of a reinforcing layer has a low elongation.

In order to solve the above-mentioned problems, the present invention provides a radial tire for a vehicle in which an organic fiber cord is spirally wound in a tire circumferential direction around a belt layer to form a reinforcing layer, and the reinforcing layer includes two organic fiber cords. Is formed by being advanced from both ends in the tire width direction toward the center. Alternatively, the reinforcing layer is formed by winding two organic fiber cords from the center in the tire width direction toward both ends.

The present invention for solving the above-described problems is directed to a method for manufacturing a radial tire for a vehicle in which an organic fiber cord is spirally wound around a belt layer in a tire circumferential direction to form a reinforcing layer. The two band members are used, and when forming the reinforcing layer, these band members are rolled from the both ends in the tire width direction toward the center. Alternatively, when the reinforcing layer is formed, these strips are wound from the center in the tire width direction toward both ends.

According to such a configuration, the distribution of the tightening force by the organic fiber cord is substantially symmetric with respect to the tire equatorial plane, so that uniformity accuracy is ensured and deterioration of conicity is prevented.

According to the present invention, since the distribution of the tightening force by the organic fiber cord is substantially symmetrical with respect to the tire equatorial plane, uniformity accuracy is ensured even when the organic fiber cord of the reinforcing layer has a low elongation. Thus, deterioration of conicity can be prevented.
Furthermore, since the organic fiber cord is discontinuous at the center of the tread portion where the input load from the road surface is small, there is almost no discoloration in strength compared to the reinforcing layer in which the organic fiber cord is continuous.

It is a mimetic diagram showing the section structure of the radial tire for vehicles of the present invention. FIG. 3 is a development view of a belt layer and a reinforcing layer in the radial tire. FIG. 4 is a diagram for explaining a cord arrangement of a belt layer and a reinforcing layer in the radial tire. FIG. 4 is a graph showing the relationship between the belt cord inclination angle and the Young's modulus in a laminated belt. It is a perspective view which shows the winding method of an organic fiber cord. It is a perspective view which shows the other winding method of an organic fiber cord. It is a perspective view of the strip | belt material which incorporated the organic fiber cord. It is a graph which shows the elongation of an organic fiber cord. It is a perspective view which shows the winding method of the conventional organic fiber cord.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radial tire for vehicles 9 Belt layer 10 Belt layer 11 Reinforcement layer 11a Organic fiber cord 12 Band material 13 Tire frame 13a Circumferential surface

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a cross-sectional structure of a radial tire for a vehicle according to the present invention, FIG. 2 is a development view of a belt layer and a reinforcing layer in the radial tire, and FIG. 3 is a diagram for explaining a cord arrangement of the belt layer and the reinforcing layer. FIG. 4 is a graph showing the relationship between the belt cord inclination angle and the Young's modulus in the laminated belt.

This vehicular radial tire (hereinafter abbreviated as "radial tire") 1 includes a tread portion 2 in contact with the ground, shoulder portions 3 provided at both ends of the tread portion 2, and sidewall portions 4 extending from the shoulder portion 3. In addition, a bead portion 5 provided at the tip of the sidewall portion 4 to be fitted to the rim R is provided, and an air chamber 16 having a substantially crown-shaped cross section is formed by these

portions

2, 3, 4, and 5. A bead core 6 and a bead filler 7 are built in the bead portion 5. The radial tire 1 includes a carcass layer 8 in which both ends are folded and coupled with a pair of bead cores 2 and bead fillers 3, two

belt layers

9 and 10 disposed outside the carcass layer 8 of the tread portion 2, and the belt layers 9. , 10 and a reinforcing layer 11 made of organic fibers disposed on the outside.

The carcass layer 8 is a rubberized cord layer forming a skeleton as a tire, and carcass cords 8a made of organic fibers such as nylon, polyester, and aromatic polyamide are arranged in a radial direction orthogonal to the tire circumferential direction (see FIG. 2).

The

belt layers

9 and 10 are rubberized cord layers having non-stretchable cords, and the carcass layer 8 is tightened by the effect to keep the tire shape. The

belt layers

9 and 10 are formed in a belt shape by bias-cutting a rubberized cord to form a band material and connecting both ends thereof. For this reason,

belt cords

9a and 10a inclined with respect to the width direction of the

belt layers

9 and 10 are embedded in the

rubber layers

9b and 10b at a predetermined pitch (see FIG. 3). For the

belt cords

9a and 10a, for example, a stranded wire of steel or organic fiber (such as aromatic polyamide) is used.

As shown in FIG. 2, the

belt layers

9 and 10 are laminated by inclining the

belt cords

9 a and 10 a in opposite directions with respect to the tire circumferential direction. Further, the inclination angles θ1 and θ2 of the

belt cords

9a and 10a with respect to the tire circumferential direction are made equal, and the values thereof are set to 45 to 65 degrees. The inclination angles θ1 and θ2 of the

belt cords

9a and 10a with respect to the tire circumferential direction are preferably closer to a singular angle of 54.7 degrees. By the way, since the

belt layers

9 and 10 are formed by bias-cutting rubberized cords at the same angle, the

belt cords

9a and 10a are aligned with respect to the tire circumferential direction by laminating both ends in the width direction in parallel. They are arranged symmetrically and the inclination angles θ1, θ2 are equal. The inner belt layer 9 is formed wider than the outer belt layer 10, and both ends of both

belt layers

9 and 10 reach the shoulder portion 3 beyond the tread portion 2.

As shown in FIG. 3, the reinforcing layer 11 is formed by spirally winding an organic fiber cord 11 a around the

belt layers

9 and 10 in the tire circumferential direction. The organic fiber cord 11a is preferably wound in a single layer aligned in the tire width direction, but may be wound in multiple layers depending on the characteristics of the radial tire. By the way, it is preferable that the organic fiber cord 11a uses a strand of an organic fiber such as an aromatic polyamide fiber, a polyarylate fiber, or a polyparaphenylene benzbisoxazole fiber. The reinforcing layer 11 is formed wider than the inner belt layer 9 so as to completely cover the belt layers 9 and 10 (see FIG. 1), so that the

belt layers

9 and 10 are peeled from both ends during high-speed rotation. Is preventing. Moreover, since the organic fiber cord 11a is wound around the

belt layers

9 and 10 in the state of the strip 12 as will be described later, the organic fiber cord 11a is actually arranged to be inclined with respect to the tire circumferential direction, but the inclination is slight. Therefore, in FIG. 2, it is ignored and the organic fiber cord 11a is drawn so as to extend in parallel to the tire circumferential direction.

By the way, as shown in FIG. 4, the Young's modulus Ex in the circumferential direction of the

laminated belt layers

9 and 10 is the maximum when the inclination angle θ (θ1 = θ2) of the

belt cords

9a and 10a is zero. It decreases rapidly with increasing θ and becomes zero at the singular angle θ0 (54.7 degrees). That is, since the rigidity in the circumferential direction is lost at the singular angle θ0, there is no difference in the tensile force in the width direction acting on the

belt layers

9 and 10 due to the ground deformation of the tire, and the torsional deformation of the tire is suppressed. Is greatly reduced. However, since the circumferential rigidity of the belt layers 9 and 10 is lost, the belt layers 9 and 10 cannot function as tires as they are. For this reason, conventionally, since the inclination angle θ of the

belt cords

9a and 10a is set to 17 to 27 degrees (range A in FIG. 4) to ensure the rigidity in the circumferential direction, the twist of the tire due to the price tear occurs. There was a point that should be improved in straight running.

On the other hand, in the present embodiment, since the inclination angles θ1, θ2 of the

belt cords

9a, 10a are set to 45 to 65 degrees, the rigidity in the circumferential direction of the belt layers 9, 10 is greatly reduced. For this reason, the difference of the tensile force with respect to the width direction of the belt layers 9 and 10 hardly arises, and the price tear by tire twist is reduced significantly. For this reason, the rolling resistance is reduced and the straight traveling performance is improved. However, since the rigidity in the circumferential direction of the belt layers 9 and 10 is significantly reduced and the tire does not function as it is, the reinforcing layer 11 is provided on the outer side of the belt layers 9 and 10 so that the circumferential rigidity of the belt layers 9 and 10 is increased. To compensate for the decline.

Thus, since the reinforcing layer 11 is formed by spirally winding the organic fiber cord 11a around the belt layers 9 and 10 in the circumferential direction of the tire, the outer side of the belt layers 9 and 10 in the radial direction due to centrifugal force during high-speed rotation. This prevents the belt layers 9 and 10 from being distorted. For this reason, peeling of the belt layers 9 and 10 becomes difficult to occur, and the high-speed durability is greatly improved.
Further, since the belt layers 9 and 10 are reinforced by the organic fiber reinforcing layer 11, the tire rigidity is maintained at an appropriate level as compared with the case where the tire rigidity is ensured only by the belt layer, and the riding comfort characteristics are improved. There will be no decline.

By the way, when the inclination angles θ1 and θ2 of the

belt cords

9a and 10a are set to singular angles, the twisting deformation at the time of contact of the belt layers 9 and 10 is eliminated, the price tear is reduced, and the steering flow is suppressed. However, even if the inclination angles θ1 and θ2 are set to 45 degrees, which is about 10 degrees smaller than the singular angle, a dramatic improvement in the price tear was confirmed by experiments. The change in the price tear due to the inclination angles θ1 and θ2 of the

belt cords

9a and 10a is considered to be symmetric with respect to the singular angle, so even if it is set to 65 degrees, which is about 10 degrees larger than the singular angle, the price tear jumps. Reduction should be expected.

Next, a method for winding the organic fiber cord 11a of the reinforcing layer 11 will be described.
FIG. 5 is a perspective view showing a method of winding an organic fiber cord, FIG. 6 is a perspective view showing another method of winding the organic fiber cord, FIG. 7 is a perspective view of a band material incorporating the organic fiber cord, and FIG. It is a graph which shows the elongation of an organic fiber cord.
In the present embodiment, the inclination angle θ1 and θ2 of the

belt cords

9a and 10a is set to 45 to 65 degrees so as to reduce the price tear, while the decrease in the circumferential rigidity of the belt layers 9 and 10 is caused by the organic fiber reinforcing layer. 11 is supplemented. For this reason, since it is necessary to increase the rigidity of the reinforcing layer 11, an aromatic polyamide fiber having a high elastic modulus or the like is used as the organic fiber cord 11a. As shown in FIG. 8, this type of fiber has a property that it is difficult to stretch as compared with a conventionally used nylon fiber or hybrid fiber (a composite fiber of nylon and aromatic polyamide). For this reason, when this type of fiber is wound around the tire skeleton 100 by the method of FIG. 9, the tightening imbalance in the vulcanization process is hardly corrected, resulting in uneven rubber flow. In other words, the looser the organic fiber cord 11a is, the easier it is for rubber to flow during the vulcanization process, resulting in a decrease in uniformity accuracy and poor conicity.

Therefore, as shown in FIG. 5, a method of using two strips 12 including the organic fiber cord 11a and winding these

strips

12 and 12 around the circumferential surface 13a of the tire frame 13 from both ends in the width direction toward the center. Adopted. Alternatively, as shown in FIG. 6, a method is adopted in which the two

strips

12, 12 are wound around the circumferential surface 13a of the tire frame 13 from the center in the width direction toward both ends. In any case, the band member 12 is wound while the end edges are in contact with each other without forming an overlap margin, and is in contact with the end edges of both the

band members

12 and 12 at the tire equator. . The tire skeleton 13 refers to a structure in which the carcass layer 8 and the belt layers 9 and 10 are inflated and held by a bladder in a green tire molding process. Then, the

strips

12 and 12 are wound around the tire skeleton 13 as described above, and the parts constituting the tread portion 2 and the sidewall portion 4 are assembled thereto to form a green tire, and the green tire is then subjected to a vulcanization process. Is heated and pressurized, and each part is integrated into a final product. The band 12 is obtained by cutting a rubberized cord into a band shape along the cord, and a plurality of organic fiber cords 11a are embedded in the rubber layer 12a (see FIG. 7). *

Even when the strip 12 is wound in this manner, the tightening tends to become tight as the winding of the strip 12 proceeds. Further, since the elongation of the organic fiber cord 11a is low, the tightening imbalance in the vulcanization process is hardly corrected. For this reason, when the winding method of FIG. 5 is adopted, the tightening force of the organic fiber cord 11a is minimized at both ends of the tire width and increases toward the inside. On the other hand, when the winding method of FIG. 6 is adopted, the tightening force of the organic fiber cord 11a is minimized at the center of the tire width and increases toward the outside. However, in any of the methods, the distribution of the tightening force by the organic fiber cord 11a is substantially symmetrical with respect to the tire equator plane, so that uniformity accuracy can be ensured and deterioration of the conicity can be prevented.

Furthermore, although any winding method is adopted, the organic fiber cord 11a is discontinuous at the center of the tread portion 2, but most of the input load from the road surface acts on the shoulder portion 3, and the tread portion. Since it does not act so much in the center of 2, compared with the case where the organic fiber cord is continuous, there is almost no fading on strength.

In the present embodiment, the tire is described in which the inclination angles θ1, θ2 of the

belt cords

9a, 10a are set to 45 to 65 degrees. However, the winding method of the organic fiber cord according to the present invention sets the inclination angle of the belt cord. The present invention can also be applied to a general tire set to 17 to 27 degrees.

Next, the comparative test performed about the Example and comparative example of this invention is demonstrated concretely.
<Example>
The radial tire of the example was produced by the following method.
A strip 12 is produced using a twisted strand of an aromatic polyamide fiber as the organic fiber cord 11a, and this is wound around the tire frame 13 by two methods shown in FIGS. 5 and 6 to produce one reinforcing layer 11 each. did. A radial tire produced by the method of FIG. 5 (a method of winding the strip 12 from both ends to the center) is set as Example 1, and a radial tire produced by the method of FIG. 6 (a method of winding the strip 12 from the center to both ends) is implemented. Example 2. The produced tire has a tire size of 195 / 65R15, a rim size of 15 × 6 J, and an air pressure of 220 kPa.

<Comparative example>
A radial tire of a comparative example was produced by the following method.
The two types of strips 12 using the strands of nylon fibers as the organic fiber cord 11a and the strands of strands of aromatic polyamide fibers are produced, and the strips 12 are shown in FIG. Thus, one reinforcing layer 11 was produced by wrapping around the tire frame 13. A tire produced by the method of FIG. 9 (a method of winding the strip 12 in one direction) using the strip 12 containing nylon fibers is referred to as a radial tire of Comparative Example 1. Further, a tire produced by the method of FIG. 9 (a method of winding the strip 12 in one direction) using the strip 12 containing the aromatic polyamide fiber is referred to as a radial tire of Comparative Example 2. In addition, the size and air pressure of the manufactured radial tire are the same as the radial tire of an Example.

<Comparison test>
High-speed test: The test was conducted according to ISO-10191. Originally, the air pressure should be 280 kPa, but this time to confirm the durability of the belt layers 9 and 10, the test was conducted under the low air pressure condition (150 kPa) until the radial tire was damaged. The distance of was measured. The test result of other radial tires tested including the examples is converted into an index with the test result of the radial tire of Comparative Example 1 as 100, and the higher the index, the better the high speed performance.
Durability test: The vehicle was run under conditions of a speed of 80 km / h, a load of 8 kN, and an air pressure of 150 kPa, and the distance to the place where the radial tire was damaged was measured. The test result of other radial tires tested including the examples is converted into an index with the test result of the radial tire of Comparative Example 1 being 100, and the larger this index is, the better the durability performance is.
RFV / LFV / conicity: Measured using a uniformity machine under conditions of an air pressure of 220 kPa and a load of 450 kg. The test result of other radial tires tested including the examples is converted into an index with the test result of the radial tire of Comparative Example 1 as 100, and the larger the index, the better each evaluation.
Table 1 shows the results of the comparative test.

As can be seen from Table 1, the radial tire of Comparative Example 2 using the method of winding the strip 12 containing the aromatic polyamide fiber in one direction uses the method of winding the strip 12 containing the nylon fiber in one direction. Compared with the radial tire of Comparative Example 1, the conicity is extremely low. This is thought to be because aromatic polyamide fibers have low elongation and uniformity uniformity is reduced due to imbalance in tightening. In the case of the radial tires of Examples 1 and 2 using the method of winding the strip 12 containing the aromatic polyamide fiber from two directions, it was confirmed that the conicity was greatly improved and improved to the same level as before. It was done. Some improvement was also observed for RFV and LFV.

Furthermore, when an aromatic polyamide fiber was used instead of nylon fiber as the organic fiber cord 11a, the rigidity of the reinforcing layer 11 was improved, and good results were obtained in a high-speed test and a durability test. In particular, a significant improvement was observed in the results of the durability test. In addition, even if the organic fiber cord 11a was discontinuous at the center of the tread portion 2, it was confirmed that there was no problem in strength. Some improvement was also observed for RFV and LFV.

Claims

In a vehicle radial tire in which a reinforcing layer is formed by spirally winding an organic fiber cord on a belt layer in the circumferential direction of the radial tire, the reinforcing layer has two organic fiber cords extending from both ends in the tire width direction toward the center. A radial tire for a vehicle characterized by being formed by winding.
In a radial tire for a vehicle in which a reinforcing layer is formed by spirally winding an organic fiber cord on a belt layer in a tire circumferential direction, the reinforcing layer winds two organic fiber cords from the center in the tire width direction toward both ends. A radial tire for a vehicle which is formed by being advanced.
In the method for manufacturing a radial tire for a vehicle in which an organic fiber cord is spirally wound around the tire layer in the tire circumferential direction to form a reinforcing layer, two rubber strips containing the organic fiber cord are used, and the reinforcing layer A method for manufacturing a radial tire for a vehicle is characterized in that, in forming the tire, the belt material is rolled up from both ends in the tire width direction toward the center.
In the method for manufacturing a radial tire for a vehicle in which an organic fiber cord is spirally wound around the tire layer in the tire circumferential direction to form a reinforcing layer, two rubber strips containing the organic fiber cord are used, and the reinforcing layer A method for manufacturing a radial tire for a vehicle is characterized in that, in forming the tire, the belt material is wound from the center in the tire width direction toward both ends.