JP4537517B2 - Manufacturing method of pneumatic radial tire - Google Patents

Description

【００４６】
【表２】

【００４７】
【表３】

【００４８】
【発明の効果】
叙上の如く本発明の製造方法によって製造された空気入りラジアルタイヤは、バンド層において、半径方向内外に重複する一方のバンドプライのバンドコード間に他方のバンドプライのバンドコードを落ち込ませ、これによって重複領域での厚さを減じている。従って、必要な耐久性を維持しながらトレッド全厚さを低く抑えることができ、転がり性能とノイズ性能とを向上させることが可能となる。
【図面の簡単な説明】
【図１】 本発明の製造方法によって製造された空気入りラジアルタイヤの一実施例を示す断面図である。
【図２】 バンド層に用いる帯状プライを例示する斜視図である。
【図３】 バンドコードの落ち込み部を示す断面図である。
【図４】 従来技術を説明するトレッド部の断面図である。
【符号の説明】
２ トレッド部
３ サイドウォール部
４ ビード部
５ ビードコア
６ カーカス
７ ベルト層
９ バンド層
１０、１０Ｆ、１０Ｅ バンドコード
１１ 帯状プライ
１２、１２Ｆ、１２Ｅ バンドプライ
１３ 落ち込み部
Ｋ 重複領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a pneumatic radial tire with improved rolling performance and noise performance while maintaining necessary durability.
[0002]
[Background Art and Problems to be Solved by the Invention]
As shown in FIG. 4, a pneumatic radial tire is widely known in which a band layer b formed by spirally winding a band cord is provided outside the belt layer a. This band layer b improves the high-speed durability performance by increasing the restraint force on the belt layer a, and can improve the steering stability by increasing the tread rigidity. Furthermore, the vibration transmission characteristics change due to the increase in the tread rigidity. In addition, there is an advantage that a shift is caused between the peak of the vibration transmissibility of the vehicle and the road noise is reduced, for example, the peak of the vibration transmissibility shifts to a higher frequency side.
[0003]
On the other hand, in the tire, in order to suppress cracking of the tread rubber g and maintain durability, it is necessary to secure a minimum rubber gauge thickness t1 (usually about 1.5 mm) at the groove bottom of the tread rubber g. Therefore, when the band layer b is formed, the total tread thickness t0 is increased by at least the thickness t2 of the band layer b.
[0004]
For example, in the band layer b, since a stronger restraining force is required on the belt layer outer end side, a full band ply b1 covering the entire belt layer a and an edge band ply b2 covering only the belt layer outer end are provided. Overlapping structures (sometimes referred to as F + E structures) are frequently used. However, even in such a structure, it is necessary to increase the rubber gauge thickness t3 corresponding to the thickness of the edge band ply b2 between the edge band plies b2 and b2 in order to prevent the contact pressure distribution from deteriorating. That is, even when the edge band ply b2 is partially arranged, the increase in the total tread thickness t0 is caused over the entire width.
[0005]
As a result, there arises a problem that the tire weight is increased and the rolling performance is deteriorated. Therefore, in order to improve this problem, it is important to keep the maximum thickness of the band layer, that is, the thickness of the band layer in a region where a plurality of band plies overlap as much as possible.
[0006]
As a band layer having an effect equivalent to the F + E structure without using the edge band ply b2, a structure in which the material of the band cord is different between the tread center side and the tread shoulder side, or JP-A-2-34403, etc. As described above, there has been proposed a structure in which the spiral pitch of the band cord is different between the tread center side and the tread shoulder side. However, the former structure increases the cost, for example, the number of types of band cord materials increases, the process becomes complicated, and the function of the molding machine needs to be added. Further, in the latter structure, in addition to the complexity of the process, the cord angle at the rough spiral pitch portion becomes large, so there is a concern that the high-speed running performance is deteriorated.
[0007]
The present invention, in the band layer, between band cord overlapping one band ply not depress the band cord of the other band ply is reduced to a thickness in the overlap region, while maintaining the necessary durability tread An object of the present invention is to provide a method for manufacturing a pneumatic radial tire that can keep the total thickness low and can improve rolling performance and noise performance.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application includes a carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a belt layer disposed inside the tread portion and outside the carcass. , With a band layer arranged on the outside of this belt layer,
The belt layer includes a belt ply in which a belt cord is inclined and arranged at an angle of 10 to 35 ° with respect to a tire circumferential direction, and the band layer has a radius of a plurality of band plies at least at an outer end portion of the belt layer. Pneumatic radial having overlapping regions placed inside and outside in the direction, and using the same band cord for the band cord of one band ply and the band cord of the other band ply adjacent to each other in the overlapping region in the radial direction A tire manufacturing method comprising:
A small band ply in which one or more band cords having a low elongation with an elongation rate of 10% or less when a load of 0.0236 g / dtex is applied is spirally wound in the tire circumferential direction. A raw tire forming step including a band layer forming step for forming each of the band plies, and a vulcanizing step of vulcanizing the raw tire in a vulcanization mold,
In the band layer forming step, each band ply is wound spirally with the side edges of the band ply abutting each other, and the direction and the inclination angle of the band cord with respect to the tire circumferential direction in the overlapping region are determined by the band ply. While being aligned with each other,
The vulcanization stretch at the time of the vulcanization process is set to 5% or more, and at the time of the vulcanization process, the band cords between the other band plies are adjacent to each other in the radial direction in the overlapping region, while the band cords between the other band plies are relatively By moving
Between the band cords of one band ply adjacent inside and outside in the radial direction, and forming a drop portion where the band cord of the other band ply falls,
The inter-cord thickness TD sandwiching the band cords of all the band plies in the overlapping region is smaller than the total value ΣS of the diameters S of the band cords of the respective band plies.
[0009]
According to a second aspect of the present invention, the inter-cord thickness TD is 0.55 to 0.90 times the total value ΣS.
[0010]
In the invention of claim 3, the band layer forming step uses, as the band cord , a low elongation band cord having an elongation rate of 10% or less when a load of 0.0236 g / dtex is applied , In addition, by setting the vulcanization stretch during the vulcanization step to 3% or less, the band cord between the other band plies adjacent to each other inside and outside in the radial direction is moved relative to the inside and outside in the radial direction to form the depressed portion. It is characterized in that the.
[0011]
In the invention according to claim 4, the belt layer has a ratio BC / of a belt camber amount BC which is a radial distance between a tire equator point and a belt outer end point on the inner surface of the belt layer with respect to a tire cross-section height H. H is in the range of the following formula (1).
BC / H ≦ 0.24-A × 0.23 (1)
In the formula, A is a tire flatness ratio.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Figure 1 shows a meridional cross section when the pneumatic radial tire 1 which is formed by the manufacturing method of the present invention (hereinafter referred to as the tire 1) is a passenger tire, the tire 1 comprises a tread portion 2, both sides A pair of sidewall portions 3 extending inward in the tire radial direction, and a bead portion 4 positioned at the inner end of each sidewall portion 3.
[0013]
Further, the tire 1 includes a toroidal carcass 6 straddling the bead portions 4, 4, a belt layer 7 disposed inside the tread portion 2 and outside the carcass 6, and an outer side of the belt layer 7. And a band layer 9 disposed on the surface.
[0014]
The carcass 6 is formed of one or more carcass plies 6A in this example, in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire circumferential direction. As the carcass cord, an organic fiber cord such as nylon, polyester, rayon, aromatic polyamide or the like is suitably employed, but a steel cord can also be employed depending on the size, category, requirement, etc. of the tire.
[0015]
In addition, the carcass 6 is folded back and locked from the inner side to the outer side around the bead core 5 on both sides of the body portion 6a from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. Part 6b. A bead apex rubber 8 is provided between the main body 6a and the folded portion 6b. The bead apex 8 extends from the bead core 5 outward in the tire radial direction. In the present example, the folded portion 6b has a so-called high turn-up structure in which the height from the bead base line BL at the radially outer end is larger than the height at the radially outer end of the bead apex rubber 8. In cooperation with the bead apex rubber 8, the bead portion 4 is reinforced and the tire lateral rigidity is enhanced. When the carcass 6 is formed of a plurality of plies, it is preferable that at least one ply has a high turn-up structure. The bead base line BL is a line in the tire axial direction that passes through the outer end point in the tire axial direction of the bead bottom surface 4S, and serves as a reference for selecting the rim diameter of the applicable rim.
[0016]
The belt layer 7 is formed of two or more belt plies 7A and 7B in this example, in which highly elastic belt cords are inclinedly arranged at an angle of 10 ° to 35 ° with respect to the tire circumferential direction. The belt plies 7A and 7B are arranged in different directions so that the belt cords cross each other between the plies. The belt triangle structure thereby increases the belt rigidity, and the tread portion 2 has a substantially full width with a tagging effect. And reinforce. As the belt cord, a steel cord or a highly elastic fiber cord such as an aromatic polyamide fiber or an aromatic polyester fiber having a strength close to steel is preferably used.
[0017]
In this example, the inner belt ply 7A is formed to be slightly wider than the outer belt ply 7B, and the stress concentration acting on the outer end of the belt is reduced.
[0018]
Next, the band layer 9 is a band ply formed by spirally winding a small band ply 11 (shown in FIG. 2) in which one or more band cords 10 are aligned in the tire circumferential direction. 12 and at least at the outer end of the belt layer 7, an overlapping region K is formed in which a plurality of band plies 12 are overlapped in the radial direction.
[0019]
Specifically, in this example, the band layer 9 includes a full band ply 12F that covers the entire width of the belt layer 7 and an edge band ply 12E that covers the outer end of the belt layer 7. It has a so-called F + E structure in which the binding force on the outer end side is higher than that on the center side (tire equator side). Therefore, in the band layer 9 of this example, the full band ply 12F and the edge band ply 12E form an overlapping region K in which the two band plies 12 overlap in the radial direction. In this example, the case where the edge band ply 12E is disposed on the inner side in the radial direction of the full band ply 12F is illustrated, but may be on the outer side in the radial direction.
[0020]
The “outer end portion of the belt layer 7” includes a range of at least 15 mm inward in the tire axial direction from the outer end of the belt layer 7 corresponding to the outer end of the wide belt ply.
[0021]
As shown in FIG. 2, the belt-like ply 11 has a narrow ribbon shape in which one or more, in this example, a cord parallel body obtained by arranging a plurality of band cords 10 is covered with a topping rubber. At this time, the number of the band cords 10 in the belt-like ply 11 is preferably about 5 to 15. If the number is too small, the ply formation efficiency is lowered. On the other hand, if the number is too large, the cord angle of the band cord becomes excessive and the binding force is increased. As a result, the function as the band layer 9 cannot be fully exhibited. The cord angle of the band cord with respect to the tire circumferential direction is generally 5 ° or less.
[0022]
In addition, the band-like ply 11 forms a full-band ply 12F and an edge-band ply 12E in which the band cords 10 are arranged at a substantially constant pitch P by causing the side edges 11e to face each other and being wound spirally. As the band cord 10, an organic fiber cord such as nylon, polyester, rayon or aromatic polyamide can be used. In this example, the case where the same band cord 10 is used for both the full band ply 12F and the edge band ply 12E is illustrated, but for convenience, the band cord of the full band ply 12F is 10F and the edge band ply 12E. May be distinguished as 10E.
[0023]
In the present application, as shown in FIG. 3, the band layer 9 is formed between the band cords 10E and 10E of one band ply 12 (in this example, the edge band ply 12E) adjacent inside and outside in the overlapping region K. The band ply 12 (in this example, the full band ply 12F) has a major feature in that the depression 13 into which the band cord 10F falls is formed.
[0024]
Here, the “sag” means that the inner edge point in the radial direction of the upper band cord 10F goes inward in the radial direction beyond the outer edge line EL that connects the outer edge points in the radial direction of the lower band cord 10E. means. For this purpose, it is necessary to align the direction and the inclination angle of the band cord 10E with respect to the tire circumferential direction with the direction and the inclination angle of the band cord 10F with respect to the tire circumferential direction. Further, the pitch PE between the band cord 10E, 10E, the pitch PF between the band cord 10F, 10F, are equal to each other, i.e., it is necessary that PE = PF.
[0025]
Thus, by forming the depression 13, the inter-cord thickness TD sandwiching the band cords 10 of all the band plies 12 in the overlapping region K is set to the diameter S of each band cord 10 of each band ply 12. It can be reduced to be smaller than the total value ΣS. That is, it is possible to reduce the thickness in the overlapping region K which is the maximum thickness of the band layer 9, and to keep the total thickness of the tread low while ensuring the minimum necessary rubber gauge thickness at the groove bottom of the tread rubber. It becomes possible. As a result, it is possible to improve rolling performance while maintaining durability.
[0026]
When the inter-cord thickness TD is equal to or greater than the total value ΣS, the total tread thickness increases and the rolling performance is impaired. When the inter-cord thickness TD is 0.5 times the total value ΣS, the band layer 9 has a substantially single layer structure. At this time, since the cord density is limited in order to ensure the cord interval between the band cords 10F and 10E, the band layer 9 has the above-mentioned functions of improving the high-speed durability performance, improving the steering stability, and The reduction of road noise cannot be achieved sufficiently. From such a viewpoint, it is preferable that the inter-cord thickness TD is 0.55 to 0.90 times the total value ΣS.
[0027]
In order for the band layer 9 to effectively function as the F + E structure, the width WE of the overlapping region K in the tire axial direction and the width WF of the full band ply 12F from the tire equator C as shown in FIG. The ratio WE / WF is preferably in the range of 1/12 to 8/12. If the ratio WE / WF is less than 1/12, the binding force on the outer end side is insufficient, and the functions of the band layer 9 such as noise reduction are not effectively exhibited. If it exceeds 8/12, the rolling performance tends to be lowered.
[0028]
Further, at the inner end point in the tire axial direction of the edge band ply, while a rigid step is generated, a circumferential groove is usually disposed in the vicinity thereof. For this reason, conventionally, the occurrence of cracks at the groove bottom has become prominent, and the width of the edge band ply (corresponding to the width WE of the overlapping region K) has been restricted, or it has been unavoidable to abandon its use. It was. However, in the present application, the formation of the sagging portion 13 relaxes the rigidity step at the inner end point of the edge band ply 12E. As a result, the occurrence of cracks is further suppressed, and there are also advantages such as the adoption of the edge band ply and the setting of the width regardless of the position of the circumferential groove.
[0029]
Next, a method for manufacturing the tire 1 will be described. This manufacturing method includes a green tire forming step including a step of forming the band layer 9 and a vulcanizing step of vulcanizing the green tire in a vulcanization mold. The step of forming the band layer 9 is as described above, and each band ply 12 is formed by winding the side edges 11e of the band-shaped ply 11 against each other and spirally winding, and the band in the overlapping region K is formed. The direction and the inclination angle of the cord with respect to the tire circumferential direction are aligned with each other between the band plies. Also, the drop portion 13 may be formed by using the raw tire vulcanization tire stretch in a vulcanizing mold during, i.e. the vulcanization stretch.
[0030]
Specifically, the vulcanization stretch at the time of vulcanization molding, which is usually about 3%, is set larger than the conventional one, for example, 5% or more, or a cord material having a lower elongation than the conventional one is used as a band cord. . In any case, at the time of vulcanization molding, the tightening effect by the upper band cord 10F acts strongly between the lower band cords 10E and 10E, and the resulting lower band cord 10E below the upper band cord 10F ( By the relative movement inward (inward in the radial direction), the depression 13 is formed.
[0031]
Here, with the means for setting the vulcanized stretch large, the deformation of the belt layer 7 and the like is increased during the vulcanization molding, and the partial rubber flow is also increased, so that the uniformity of the tire is lowered. For example, it is disadvantageous for vibration characteristics.
[0032]
Accordingly, a means using the low elongation band cord 10 can be preferably employed. That is, as the band cord 10, one having an elongation rate of 10% or less when a load of 0.0236 g / dtex is applied. As a result, it is possible to secure the necessary restraint force by the band layer 9 even in a vulcanized stretch of about 3% while enabling the formation of the sagging portion 13, and the functions of the band layer 9 (improvement of high-speed durability performance, steering) Stability improvement and road noise reduction can be effectively demonstrated.
[0033]
The elongation rate of the conventional nylon band cord is about 14%. The elongation is a value measured according to JISL1017.
[0034]
In particular, the band cord 10 having an elongation of 5% or less can form a larger sagging portion 13 even in a vulcanized stretch of less than 3%, and the restraint force is further increased, so that the function of the band layer 9 is further improved. Moreover, further improvement in uniformity can be expected by reducing the vulcanized stretch. An aromatic polyamide fiber cord is suitable as the band cord 10 with an elongation of 5% or less, and a nylon fiber cord is suitable as the band cord 10 with an elongation of 5 to 10%.
[0035]
In forming the sagging portion 13, when the band cord itself is thick or when the cord density R of the band cord is high (the number of cords per 1 cm width of the ply), the relative movement of the band cord in the radial direction tends to be hindered. This is disadvantageous. Therefore, the diameter S of the band cord 10 is preferably 0.9 mm or less, and the cord density R is preferably 13/1 cm or less.
[0036]
Further, the product S × R of the diameter S of the band cord 10 and the cord density R is an index of the band cord occupation ratio in the band ply. The smaller the product S × R, the easier the relative movement of the band cord. And also advantageous for uniformity. Therefore, the product S × R is preferably 8.0 or less.
[0037]
In addition, as described above, the ratio BC / H between the belt camber amount BC of the belt layer 7 and the tire cross-section height H is determined because the sagging portion 13 is formed using a vulcanized stretch at the time of vulcanization molding. In an excessive tire, that is, a tire having a small radius of curvature, there is a problem that the difference in vulcanization stretch between the tread center side and the tread shoulder side becomes too large, making manufacture difficult and significantly impairing uniformity.
[0038]
Therefore, it is necessary to regulate the ratio BC / H within the range of the following formula (1).
BC / H ≦ 0.24-A × 0.23 (1)
In the equation, A is the tire flatness, and when the flatness is 60%, A = 0.60. The belt camber amount BC means a radial distance between the tire equator point and the belt outer end point on the inner surface of the belt layer 7 as shown in FIG.
[0039]
The belt camber amount BC, the tire cross-section height H, and the flattening ratio A are values measured with the tire assembled on a regular rim and filled with a regular internal pressure. “Regular rim” is defined by JATMA. Standard rim, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. “Regular internal pressure” means the maximum air pressure specified by JATMA, the maximum value described in the TRA table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “INFLATION PRESSURE” specified by ETRTO. In some cases, it is 180 KPa.
[0040]
【Example】
A tire having a tire size of 195 / 60R15 and having the structure shown in FIG. 1 is manufactured on the basis of the specifications shown in Tables 1 to 3, and the rolling performance, durability performance, road noise performance, and uniformity of each sample tire are tested. Compared.
[0041]
The test method is as follows.
(1) Rolling performance:
Using a rolling resistance tester, the rolling resistance when the sample tire was run at a rim (15 × 6.5JJ), internal pressure (230 kPa), load (4.0 kN), speed (80 km / h) was measured, The results are shown as an index when Comparative Example 1 (conventional tire) is set to 100. A larger index is better.
[0042]
(2) Durability:
Cracks generated at the bottom of the groove after the sample tire was run on the drum for 100 km at a speed of 60 km / h on the basis of a rim (15 × 6.5JJ), internal pressure (200 kPa), and load (5.5 kN) Were visually inspected, and those that were confirmed to have cracks were considered defective.
[0043]
(3) Road noise performance:
The sample tires were mounted on all wheels for passenger cars (1600cc, FF cars) with a rim (15 × 6.5JJ) and internal pressure (210kPa), and the smooth road surface was run at a speed of 50km / h. Evaluation was performed by a 5-point method. The larger the value, the smaller the noise level and the better.
[0044]
(4) Uniformity:
In accordance with JASO C607 “Testing method for vehicle tire uniformity”, RFV was measured under the conditions of rim (15 × 6.5JJ), internal pressure (200 kPa), load (4.0 kN), rotation speed (60 rpm), The RFV primary value at that time was displayed as an index when Comparative Example 1 (conventional tire) was set to 100. A larger index is better.
[0045]
[Table 1]

[0046]
[Table 2]

[0047]
[Table 3]

[0048]
【The invention's effect】
As described above, in the pneumatic radial tire manufactured by the manufacturing method of the present invention, in the band layer, the band cord of the other band ply is depressed between the band cords of one band ply overlapping in the radial direction. Reduces the thickness in the overlap region. Therefore, the total thickness of the tread can be kept low while maintaining the required durability, and the rolling performance and noise performance can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a pneumatic radial tire manufactured by the manufacturing method of the present invention.
FIG. 2 is a perspective view illustrating a belt-like ply used for a band layer.
FIG. 3 is a cross-sectional view showing a band cord drop portion;
FIG. 4 is a cross-sectional view of a tread portion for explaining a conventional technique.
[Explanation of symbols]
2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 7 Belt layer 9 Band layer 10, 10F, 10E Band cord 11 Band-like ply 12, 12F, 12E Band ply 13 Depressed portion K Overlapping region

Claims (4)

A carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, a belt layer disposed inside the tread portion and outside the carcass, and a band layer disposed outside the belt layer,
The belt layer includes a belt ply in which a belt cord is inclined and arranged at an angle of 10 to 35 ° with respect to a tire circumferential direction, and the band layer has a radius of a plurality of band plies at least at an outer end portion of the belt layer. Pneumatic radial having overlapping regions placed inside and outside in the direction, and using the same band cord for the band cord of one band ply and the band cord of the other band ply adjacent to each other in the overlapping region in the radial direction A tire manufacturing method comprising:
A small band ply in which one or more band cords having a low elongation with an elongation rate of 10% or less when a load of 0.0236 g / dtex is applied is spirally wound in the tire circumferential direction. A raw tire forming step including a band layer forming step for forming each band ply, and a vulcanizing step of vulcanizing the raw tire in a vulcanization mold,
In the band layer forming step, each band ply is wound spirally with the side edges of the band ply abutting each other, and the direction and the inclination angle of the band cord with respect to the tire circumferential direction in the overlapping region are determined by the band ply. While being aligned with each other,
The vulcanization stretch at the time of the vulcanization process is set to 5% or more, and at the time of the vulcanization process, the band cords between the other band plies are adjacent to each other in the radial direction while adjacent to each other in the radial direction. By moving
Between the band cords of one band ply adjacent inside and outside in the radial direction, and forming a depression portion where the band cord of the other band ply falls,
The production of a pneumatic radial tire characterized in that the inter-cord thickness TD sandwiching the band cords of all the band plies in the overlapping region is smaller than the total value ΣS of the diameters S of the band cords of the respective band plies. Method.   The method for manufacturing a pneumatic radial tire according to claim 1, wherein the inter-cord thickness TD is 0.55 to 0.90 times the total value ΣS.   In the band layer forming step, a low-stretch band cord having an elongation rate of 10% or less when a load of 0.0236 g / dtex is applied is used as the band cord, and the vulcanization step is performed. The squeeze stretch is set to 3% or less, and the band cord between the other band plies adjacent to each other in the radial direction is relatively moved inward and outward in the radial direction to form the sagging portion. A method for producing a pneumatic radial tire according to 1 or 2. In the belt layer, a ratio BC / H of a belt camber amount BC which is a radial distance between a tire equator point and a belt outer end point on the inner surface of the belt layer with respect to a tire cross-section height H is represented by the following formula (1). The method for manufacturing a pneumatic radial tire according to claim 1, 2 or 3, wherein
BC / H ≦ 0.24-A × 0.23 (1)
In the formula, A is a tire flatness ratio.

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