JP2015227096A - Pneumatic tire and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which does not reduce durability performance and which improves performance about rolling resistance.SOLUTION: At least one piece 10 of belt plys comprises: plural first cords 12 extending with equal intervals in a same direction; plural second cords 14 extending with equal intervals in a same direction and being inclined with respect to the first cords 12; and a rubber 16 for covering the first cords 12 and the second cords 14, in plan perspective view. The first cords 12 and the second cords 14 are continuously dotted in a tire direction with once crossover so that tire radial direction positions of the respective first cord and second cord are replaced, in a tire meridian cross sectional view.

Description

  The present invention relates to a pneumatic tire and a method for manufacturing the same, in which performance relating to rolling resistance is improved without impairing durability.

  In recent years, from the viewpoint of consideration for the environment, there has been known a technique for reducing the fuel consumption of a tire, specifically, improving performance related to rolling resistance (see Patent Documents 1 and 2). The technique disclosed in Patent Document 1 is a technique in which the value of the index tanδ that affects the rolling resistance is remarkably improved. The technique disclosed in Patent Document 2 is a technique in which a cord is provided at the center in the tire width direction of the carcass ply. This is a technology that reduces the weight of the tire without disposing it.

JP-A-7-133377 Japanese Patent Laid-Open No. 11-11108

  However, as in the technique disclosed in Patent Document 1, when an additive such as silica is included in the rubber composition, the tread rubber is likely to be worn out, so that it may not be possible to exhibit excellent durability performance. is there.

  In addition, as in the technique disclosed in Patent Document 2, when the carcass cord does not exist between both crown portions, the out-of-plane bending rigidity of the ground contact region is reduced. For this reason, a contact area will deform | transform excessively at the time of tire rolling, and there exists a possibility that the outstanding durability performance cannot be exhibited.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the pneumatic tire which improved the performance regarding rolling resistance, without impairing durability performance.

  A pneumatic tire according to the present invention includes a carcass layer formed between a pair of bead portions, and a belt layer made of at least one belt ply formed on the tread portion on the outer side in the tire radial direction of the carcass layer. A tread rubber formed on the outer side of the belt layer in the tire radial direction. In a plan view, at least one of the belt plies includes a plurality of first cords extending in the same direction at equal intervals, and a plurality of first cords inclined with respect to the first cord and extending in the same direction at equal intervals. A second cord; and a rubber covering the first cord and the second cord. In the tire meridian cross-sectional view, the first cord and the second cord are crossed once so that the positions in the tire radial direction are interchanged, and are continuously scattered in the tire width direction.

  The method for manufacturing a pneumatic tire according to the present invention includes a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and an inspection step after vulcanization. In the tire material processing step, at least one cord is covered with rubber to form a plurality of strips, and two kinds of strips extending in different directions are interchanged in the stacking direction. Cross once to form a strip composite as the material for the belt layer.

  The pneumatic tire according to the present invention uses the above-described manufacturing method to improve the arrangement of two types of cords that are constituent elements of the belt layer. As a result, according to the pneumatic tire according to the present invention, the performance related to rolling resistance can be improved without impairing the durability performance.

FIG. 1 shows a belt ply constituting a belt layer included in the pneumatic tire of the present embodiment, (a) is a plan perspective view thereof, and (b) is an AA ′ line of (a). FIG. FIG. 2 is a tire meridional sectional view showing an example of a belt layer included in the pneumatic tire of the present embodiment. FIG. 2A is a diagram in which belt plies 10 and 10 shown in FIG. (B) and (c) are examples in which the belt ply 10 shown in FIG. 1 (b) and a known belt ply 20 are laminated in the tire radial direction, respectively. FIG. 3 is a tire meridian cross-sectional view showing a modification of the belt layer of the present embodiment. FIG. 3A shows belt plies 30 and 30 which are modifications of the belt ply 10 used in FIG. 2 in the tire radial direction. In this example, the belt plies 30 and the known belt plies 40 and 50 are laminated in the tire radial direction, respectively. FIG. 4 is a flowchart showing a method for manufacturing the pneumatic tire of the present embodiment. FIG. 5 is a flowchart showing a processing procedure of the belt layer material in the tire material processing step shown in FIG. 4. FIG. 6 shows a strip that can be used in the step of forming the strip composite shown in FIG. 5, wherein (a) is a schematic cross-sectional view in the longitudinal direction, and (b) to (d) are each in the width direction. Different examples of cross-sectional views (cross-sectional views taken along line DD ′ in FIG. 5A) are shown. FIG. 7 is a perspective view specifically showing a forming method in the step of forming the strip composite shown in FIG. 5. FIG. 7A shows the second strip 62 with respect to the first strip 60 and the stacking direction thereof. A state of crossing once so that the positions are switched is shown, and (b) and (c) show examples of states that can be taken after the state shown in (a). FIG. 8 is a plan view showing a stacking mode of strips in the strip composite according to the present embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a pneumatic tire according to the present invention (basic form 1 and additional forms 1-1 to 1-4 shown below) and an embodiment of the method for manufacturing a pneumatic tire according to the present invention will be described. A form (basic form 2 and additional forms 2-1 to 2-5 shown below) will be described in detail based on the drawings. Note that these embodiments do not limit the present invention. In addition, the constituent elements of the above embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Furthermore, various forms included in the above-described embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis of the pneumatic tire, the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, and the tire radial direction outer side refers to the tire diameter. The side away from the rotation axis in the direction. The tire circumferential direction refers to a circumferential direction with the rotation axis as a central axis. Furthermore, the tire width direction refers to a direction parallel to the rotation axis. The tire equator plane is a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire.

<Pneumatic tire>
[Basic form 1]
Below, basic form 1 about a pneumatic tire concerning the present invention is explained. The pneumatic tire according to the present embodiment has a carcass layer formed between a pair of bead portions, similarly to a general pneumatic tire. The pneumatic tire has a belt layer made of at least one belt ply formed on the outer side in the tire radial direction of the carcass layer in the tread portion. Furthermore, the pneumatic tire includes a tread rubber formed on the outer side in the tire radial direction of the belt layer.

  FIG. 1 shows a belt ply constituting a belt layer included in the pneumatic tire of the present embodiment. In the figure, (a) is a plan perspective view thereof, and (b) is a tire meridional sectional view taken along the line AA ′ of (a). In FIG. 1 (a), the solid line indicates the first cord formed at equal intervals and inclined in one direction with respect to the tire circumferential direction, and the dotted line is inclined in the other direction with respect to the tire circumferential direction. The 2nd code | cord | chord formed at equal intervals is shown. In FIG. 1 (b), a circle indicates the first code shown in FIG. 1 (a) with its dimensions and shape exaggerated, and a triangle indicates the second code shown in FIG. 1 (a). The dimensions and shape are exaggerated.

  As shown in FIG. 1A, the belt ply 10 has a plurality of first cords 12 extending at equal intervals in the same direction, and is inclined with respect to the first cord 12 and extended at equal intervals in the same direction. A plurality of second cords 14 and a rubber 16 covering the first cord 12 and the second cord 14.

  As shown in FIG. 1B, the belt ply 10 has the first cord 12 and the second cord 14 intersecting once so that the positions in the tire radial direction are interchanged, and continuously in the tire width direction. Exist.

  Here, as the 1st cord 12 and the 2nd cord 14, a single wire cord may be used, and what is called a strand which twisted a plurality of cords may be used. In addition, these cords 12 and 14 can all be steel cords, organic fiber cords (for example, cords including polyester, nylon, aramid, polyketone, or rayon), and a combination thereof. In addition, about the rubber | gum 16, any well-known rubber | gum can be used and rubber | gum different from the rubber | gum used for layers (for example, tread) other than a belt layer can also be used.

  Moreover, the extension angle with respect to the tire circumferential direction of the 1st cord 12 and the 2nd cord 14 shown in Drawing 1 (a) can be 15 degrees or more and 35 degrees or less. Further, the number of belt ply cord ends in the tire meridional cross section (defined by the number of cords per 50 mm width at a height substantially parallel to the tire width direction, for example, in the example shown in FIG. 1B) If present, the number of the first cords 12 and the second cords at a height substantially parallel to the tire width direction, that is, the total number of circles and triangles shown in FIG. Can be 20 or more and 40 or less. In addition, the diameter of each of the first cord 12 and the second cord 14 is 0.2 mm or more and 4.0 mm or less (the diameter in the case of a single wire, the maximum diameter in the case of a strand), preferably 0. It can be 4 mm or more and 3.0 mm or less.

  FIG. 2 is a tire meridian cross-sectional view showing an example of a belt layer included in the pneumatic tire of the present embodiment. In the figure, (a) is an example (belt layer B1) in which the belt plies 10 and 10 shown in FIG. 1 (b) are laminated in the tire radial direction. FIG. 2B is an example (belt layer B2) in which a known belt ply 20 is laminated on the outer side in the tire radial direction of the belt ply 10 shown in FIG. 1B. FIG. 2C shows an example (belt layer B3) in which the belt ply 10 shown in FIG.

  In addition, the belt layer contained in the pneumatic tire of this Embodiment is not restricted to three examples shown in FIG. That is, the belt layer includes at least one belt ply 10 shown in FIG. 1 (b) as an essential component, and at least one known belt ply 20 or the like as an optional component. Is formed. For this reason, for example, the belt layer includes only one belt ply 10 shown in FIG.

(Action etc.)
In the pneumatic tire according to the present embodiment, as shown in FIG. 1 (b), with respect to the belt ply 10, the first cord 12 and the second cord 14 are crossed once so that the positions in the tire radial direction are interchanged. In the tire width direction. Under such a structure, when the tire rolls, each side in the tire width direction of the tire equatorial plane CL of the belt ply 10 is opposite in a plane perpendicular to the tire equatorial plane CL (FIG. 1 (a ) And (b) indicated by arrows X1 and X2) are repeatedly subjected to shear deformation (however, the arrows X1 and X2 are directions of stress applied to the respective sides of the belt ply 10 when the tire rolls in a certain direction). is there). Here, in the conventional belt ply structure, the entire tire width direction of the belt ply undergoes shear deformation in the same direction, so that the tire ground contact surface rolls while being twisted. On the other hand, in the present embodiment, the shear deformation of the belt ply is canceled by the belt ply 10 as a whole, so that the torsional deformation of the tire ground contact surface is suppressed, and excessive deformation of the tire itself during rolling occurs. It becomes a state that does not. Therefore, according to the present embodiment, it is possible to efficiently bias the tire only in the straight traveling direction by suppressing the torsional deformation of the tire itself at the time of tire rolling, particularly when the vehicle is traveling straight ahead. Can be achieved, and excellent performance related to rolling resistance can be realized.

  Further, in the present embodiment, as in the technique of Patent Document 2, the performance relating to rolling resistance is not improved by reducing the weight without the presence of a carcass cord between both crown portions, Improvements have been made to the arrangement of the cords to improve the performance related to rolling resistance. For this reason, the tread portion (including elements extending from the inner liner to the outermost tread rubber in the tire radial direction) in the present embodiment achieves superior rigidity compared to the tread portion disclosed in Patent Document 2. It is possible to prevent the durability from being impaired.

  In addition, the said effect (the effect regarding rolling resistance and the effect regarding durability performance), as shown in FIG.1 (b), the frequency | count of replacement | exchange of the tire radial direction position of the 1st cord 12 and the 2nd cord 14 is 1 time. A lot depends on something. That is, when the number of replacements is an even number, when the tire rolls, the region deformed in the rotation direction X1 and the region deformed in the rotation direction X2 shown in FIG. 1B are mixed in the tire width direction. The torsional deformation of the tire ground contact surface cannot be effectively suppressed. Therefore, when the number of replacements is an even number, the tire itself is excessively deformed when the tire rolls, and the torsional deformation of the tire itself cannot be suppressed particularly when the vehicle goes straight. As a result, since the tire cannot be urged at a high level only in the straight direction, energy loss cannot be sufficiently suppressed, and excellent performance relating to rolling resistance cannot be realized.

  Further, even if the number of times of replacement is an odd number, if the number of times of replacement is three or more, the total number of the region deformed in the rotation direction X1 and the region deformed in the rotation direction X2 shown in FIG. It becomes 4 or more, and there will be a large number of regions that deform in a specific direction in the tire width direction. Therefore, when the number of replacements is 3 times or more, the belt ply includes many boundaries between adjacent regions that deform in the opposite direction, and the stress is excessive with respect to other regions at the boundary. As a result, excellent durability cannot be achieved.

  As described above, the pneumatic tire according to the present embodiment is improved in the arrangement of the two types of cords that are constituent elements of the belt layer, thereby suppressing energy loss during tire rolling and the tread portion. It is possible to achieve both prevention of a decrease in rigidity. As a result, according to the pneumatic tire according to the present invention, the performance related to rolling resistance can be improved without impairing the durability performance.

  In addition, although not shown in figure, the pneumatic tire which concerns on this Embodiment shown above has the same meridional cross-sectional shape as the conventional pneumatic tire. Here, the meridional cross-sectional shape of the pneumatic tire refers to a cross-sectional shape of the pneumatic tire that appears on a plane perpendicular to the tire equatorial plane. The pneumatic tire according to the present embodiment has a bead portion, a sidewall portion, a shoulder portion, and a tread portion from the inner side in the tire radial direction toward the outer side in a tire meridian cross-sectional view. The pneumatic tire includes, for example, a carcass layer extending from a tread portion to bead portions on both sides and wound around a pair of bead cores in a tire meridional section, and a tire radial outside of the carcass layer. The belt layer and the belt reinforcing layer are sequentially formed.

[Additional Forms 1-1 to 1-4]
Next, additional embodiments 1-1 to 1-4 that can be optionally implemented with respect to the basic embodiment 1 of the pneumatic tire according to the present invention will be described.

(Additional form 1-1)
In the basic form 1, as shown in FIG. 1A, among the overlapping portions of the first cord 12 and the second cord 14 in a plan view, overlapping portions adjacent to each other in the tire circumferential direction (for example, point P1) And the points P2 or the points P3 and P4) are preferably parallel to the tire circumferential direction (additional form 1-1).

  Uniformity in the tire circumferential direction is obtained by making a line segment connecting overlapping portions adjacent to each other in the tire circumferential direction out of the overlapping portions of the first cord and the second cord in plan perspective, parallel to the tire circumferential direction. Can be increased. As a result, in this embodiment, lateral force variation (Lateral Force Variation (LFV)) can be suppressed particularly when the tire rolls, and as a result, performance related to rolling resistance can be further improved.

(Additional form 1-2)
In the basic form 1 and the form in which the additional form 1-1 is added to the basic form 1, the tire in the tire width direction region C in which the distance between the first cord 12 and the second cord 14 is the smallest in the tire meridional section. It is preferable that a land portion is formed on the radially outer side to reach the tread surface (additional form 1-2). Here, the tire width direction region C is, as shown in FIG. 1B, the tire width direction including at least the tire width direction region of the cords 12a and 14a having the smallest tire radial direction distance between the cords. An area.

  In the present embodiment, the land portion is formed on the outer side in the tire radial direction of the tire width direction region C until reaching the tread surface (that is, the groove is not formed). Thereby, among the cords 12a and 14a having the smallest distance in the tire radial direction, the tire radial direction dimension from the cord 14a located on the outer side in the tire radial direction to the tread surface can be sufficiently secured. Since the distance between the cords of the first cord 12a and the second cord 14a is smaller in the tire width direction region C than in other tire width direction regions, the peripheral region of these cords 12a and 14a is other region. Compared to, it is likely to become the base point of failure. However, in the present embodiment, since a sufficient rubber layer exists between the tread surface and the second cord 14a on the outer side in the tire radial direction, even if the tire surface is deformed, the stress applied in the deformation is not reduced. The area around the cords 12a and 14a is reached in a considerably attenuated state. For this reason, it is suppressed that stress is excessively applied to the peripheral region, and failures in the peripheral region are suppressed, so that the durability performance can be further enhanced.

  Two cords 12a existing in the tire width direction region C are provided by separating the both ends of the groove disposed on the tread surface by 5 mm or more from each side in the tire width direction of the tire width direction region C. The dimension from each of 14a to the groove bottom of the groove can be sufficiently secured. Thereby, even if the tire surface (including the groove bottom and the groove wall) is deformed, the stress applied in the deformation reaches the peripheral region of the cords 12a and 14a in an extremely attenuated state. For this reason, it is further suppressed that stress is excessively applied to the peripheral region, and the occurrence of a failure in the peripheral region is further suppressed, so that the durability performance can be further improved.

(Additional form 1-3)
In the basic form 1 and the form obtained by adding at least one of the additional forms 1-1 and 1-2 to the basic form 1, as shown in FIG. The maximum rubber gauge G between the first cord 12 and the second cord 14 is preferably 0.2 mm or more and 2.5 mm or less (additional form 1-3).

  When the maximum rubber gauge G between the first cord 12 and the second cord 14 at the same position in the tire width direction is 0.2 mm or more in the tire meridian cross-sectional view, the first cord 12 and the second cord 14 It is possible to secure a larger dimension in the tire radial direction. Thereby, when the tire surface is deformed, even if the stress applied in the deformation reaches the peripheral region of the cords 12 and 14, the rubber interposed between the cords 12 and 14 serves as a cushioning material. It will fulfill enough. As a result, the occurrence of a failure in the peripheral area is further suppressed, so that the durability performance can be further improved. In addition to increasing the tire radial dimension of the rubber interposed between the cords 12 and 14 shown in FIG. 1 (b), the tire width of the belt ply 10 as shown in FIGS. 1 (a) and 1 (b). The durability performance of the belt ply 10 can also be improved by forming regions made only of rubber without extending the cords 12 and 14 at both ends in the direction.

  In addition, the belt ply shown in FIG. 1 (b) can be obtained by setting the maximum rubber gauge G between the first cord 12 and the second cord 14 at the same position in the tire width direction in the meridional section of the tire to 2.5 mm or less. An excessive increase in the amount of rubber in 10 can be prevented. As a result, the weight can be reduced, and the performance related to rolling resistance can be further enhanced.

  In addition, the said effect can be show | played by a higher level by making the said maximum rubber gauge G into 0.3 mm or more and 2.0 mm or less, respectively.

(Additional form 1-4)
In the basic form 1 and the form in which at least one of the additional forms 1-1 to 1-3 is added to the basic form 1, the tire of the first cord is on at least one side in the tire width direction in the tire meridional section view. It is preferable that the outermost position in the width direction is different from the outermost position in the tire width direction of the second cord (additional form 1-4).

  FIG. 3 is a tire meridional sectional view showing a modification of the belt layer of the present embodiment. In the figure, (a) shows that the outermost position in the tire width direction of the first cord (circle) is different from the outermost position in the tire width direction of the second cord (triangle) on both sides in the tire width direction. This is an example in which the belt plies 30 and 30 are laminated in the tire radial direction (belt layer B4).

  The distance between the cords located on the outermost side in the tire width direction of the belt ply 30 shown in FIG. 3A (for example, the distance between the cord 12b2 and the cord 14b2 or the distance between the cord 12c2 and the cord 14c2) is as shown in FIG. The distance between cords (for example, the distance between the cord 12b1 and the cord 14b1 or the distance between the cord 12c1 and the cord 14c1) located on the outermost side in the tire width direction of the belt ply 10 shown in FIG. Therefore, in the example shown in FIG. 3A, when the tire surface is deformed, even if the stress applied in the deformation reaches the vicinity of the outermost cord in the tire width direction, There is a sufficient rubber layer acting as a cushioning material between the positioned cords. As a result, the occurrence of a failure in the vicinity of the outermost cord in the tire width direction is suppressed, so that the durability performance can be further enhanced.

  In the example shown in FIG. 3A, adjacent belt plies 30 stacked not only between two cords (circle code and triangle code) in one belt ply 30 but also in the tire radial direction. 30, the outermost positions in the tire width direction are also made different between the cords adjacent to each other in the tire radial direction (a round cord and a round cord). Thereby, the occurrence of a failure in the vicinity of the outermost cord in the tire width direction can be suppressed not only between the same belt plies but also between adjacent belt plies, so that the durability performance can be further enhanced.

  Next, FIGS. 3B and 3C are examples of belt layers B5 and B6 in which the belt ply 30 shown in FIG. 3A and known belt plies 40 and 50 are laminated in the tire radial direction, respectively. is there. Also in the example shown in FIGS. 3B and 3C, the durability performance can be improved as in the example shown in FIG. The distance between the cords located on the outermost side in the tire width direction described above is preferably 5 mm or more and 15 mm or less. By setting the distance between the cords to 5 mm or more, the buffer function of the rubber layer existing between these cords can be further enhanced, and the durability performance can be further enhanced. Further, by setting the distance between the cords to 15 mm or less, it is possible to further improve the performance relating to rolling resistance by suppressing an increase in weight of the tire without excessively providing a rubber layer between these cords.

<Pneumatic tire manufacturing method>
[Basic form 2]
Below, basic form 2 about the manufacturing method of the pneumatic tire concerning the present invention is explained. FIG. 4 is a flowchart showing a method for manufacturing the pneumatic tire of the present embodiment. As shown in the figure, the pneumatic tire manufacturing method of the present embodiment is in accordance with a general manufacturing method, in which a tire material mixing step, a tire material processing step, a green tire molding step, Including a sulfur process and an inspection process. In particular, the present embodiment is characterized by the tire material processing step, and therefore the tire material processing step will be described in detail below.

  FIG. 5 is a flowchart showing a processing procedure of the belt layer material in the tire material processing step shown in FIG. 4. As shown in the figure, the processing procedure of the material for the belt layer in the present embodiment includes a strip forming step and a strip composite forming step. In particular, the present embodiment is characterized by the step of forming the strip composite.

  In the strip formation stage shown in FIG. 5, after selecting at least one of a steel cord and an organic fiber cord and preparing these cords as single wires, or twisting these cords into strands, Cover the cord or strand with a rubber material. Any known technique can be used for the strip formation stage. The width of the strip (the rubber gauge dimension in the direction perpendicular to the extending direction) can be 0.3 mm or more and 1.0 mm or less.

  FIG. 6 shows a strip that can be used in the formation stage of the strip composite shown in FIG. In FIG. 6, symbol S (S1, S2, S3) indicates a strip, symbol SC (SC1, SC2, SC3) indicates a code, and symbol SG indicates a rubber material. In the figure, (a) is a schematic sectional view of the strip S in the longitudinal direction. FIGS. 6B to 6D are different examples of cross-sectional views in the width direction of the strip (cross-sectional views taken along line DD ′ in FIG. 6A). In addition, (b) is a case where a single wire is used alone, (c) is a case where a plurality of single wires are used, and (d) is an example using a strand in which a single wire is twisted.

  Hereinafter, the step of forming the strip composite will be described in detail. FIG. 7 is a perspective view specifically showing the forming method in the step of forming the strip composite shown in FIG. In FIG. 7, (a) shows a state in which the second strip 62 is crossed once with respect to the first strip 60 so that the positions thereof are switched in the stacking direction. In this state, in the left half of the page, the second strip 62 is located on the back side of the page with respect to the first strip 60, and in the right half of the page, the second strip 62 is located on the front side of the page with respect to the first strip 60. Represents what to do.

  Next, FIG. 7B shows an example of states that can be taken after the state shown in FIG. That is, FIG. 7B shows a state in which, from the state shown in FIG. 7A, the third strip 64 is crossed once with respect to the first strip 60 so that the positions are switched in the stacking direction.

  Similarly, FIG. 7C shows another example of states that can be taken after the state shown in FIG. That is, FIG. 7C shows a state where the third strip 66 is crossed once with respect to the second strip 62 so that the positions thereof are switched in the stacking direction from the state shown in FIG.

  Then, a new strip is sequentially arranged with respect to the existing strip so as to intersect once so that the stacking direction is changed. That is, from the state of FIG. 7A to the state of FIG. 7B or the state of FIG. 7C, the region surrounded by the dotted line in FIG. 7B or FIG. A plurality of other strips are sequentially arranged so as to fill all. As a result, the region surrounded by the dotted line in both figures is filled with a plurality of strips parallel to either the first strip 60 or the second strip 62, and a strip composite is obtained.

  The strip composite thus obtained is used as a material for a belt layer in a green tire molding process. And a predetermined pneumatic tire is obtained by passing through a normal vulcanization process and an inspection process.

(Function)
In the manufacturing method of the pneumatic tire of the present embodiment, two types of strips extending in different directions are used, and these are crossed once so that the positions in the stacking direction are switched to form a strip composite. The composite is used as the material for the belt layer. As a result, the product tire (pneumatic tire) includes the belt ply having the structure shown in FIGS. 1A and 1B, and as described above, the arrangement of the two types of cords that are constituent elements of the belt layer Will be improved. As a result, it is possible to achieve both suppression of energy loss during rolling of the tire and prevention of rigidity reduction of the tread portion, and consequently, performance relating to rolling resistance can be improved without impairing durability performance.

[Additional Forms 2-1 to 2-5]
Next, additional modes 2-1 to 2-5 that can be optionally implemented with respect to the basic mode 2 of the method for manufacturing a pneumatic tire according to the present invention will be described.

(Additional Form 2-1)
FIG. 8 is a plan view showing a stacking mode of strips in the strip composite according to the present embodiment. In addition, the thick line in FIG. 8 is those outlines shown in order to emphasize the strip 72a and the strip 72b.

  In the basic mode 2, as shown in FIG. 8, in a plan view, two types of strips 72a (strips extending from the lower left to the upper right in the figure) and strips 72b (lower right in the figure) are viewed in different directions. Strips extending so that the line segment connecting the ends E1 and E2 in the extending direction of the strip composite 70 is parallel to the extending direction of the strip composite 70. Forming complex 70 (additional form 2-1) is preferred. As shown in FIG. 8, the extending direction of the strip composite 70 refers to the longitudinal direction of the strip composite 70, and corresponds to the tire circumferential direction in a product tire manufactured using the strip composite 70.

  When the strip composite is formed in this way, since the belt cord is usually located at the center in the width direction of the strip, in the product tire (pneumatic tire), as shown in FIG. A line segment connecting overlapping portions adjacent to each other in the tire circumferential direction (for example, point P1 and point P2 or point P3 and point P4) among the overlapping portions of the first core 12 and the second cord 14 in plan perspective. Is parallel to the tire circumferential direction. As a result, the uniformity in the tire circumferential direction can be increased, and as a result, the lateral force variation (Lateral Force Variation) at the time of rolling of the tire can be suppressed, and the performance related to rolling resistance can be further improved.

(Additional form 2-2)
In the basic form 2 and the form in which the additional form 2-1 is added to the basic form 2, the width of the strip composite in the layered region of the two types of strips in the region where the stacking direction positions of the strips are interchanged. It is preferable that the directional dimension is 1/3 or less of the width of the strip composite (additional form 2-2). As shown in FIG. 8, the width direction of the strip composite 70 refers to the short direction of the strip composite 70. In a product tire manufactured using the strip composite 70, the width direction corresponds substantially to the tire width direction. .

  The substantially rhombus regions shown in FIG. 8 are all regions where two types of strips are laminated. Among these, the hatched area shown in the figure is an area where the stacking direction positions of the strips are switched (stacking direction switching area).

  On the both sides in the width direction of the strip composite in the stacking direction changing region, twisting deformations in opposite directions occur when the product tire rolls, but these deformations are canceled as a result. However, in the stacking direction switching region, due to the stacking mode, torsional deformation on the same side as any region in the width direction occurs. For this reason, when the width direction dimension of the stacking direction replacement region is relatively large, when viewed as the strip composite as a whole, torsional deformation in either direction remains when rolling the product tire, and the lateral force It is difficult to sufficiently suppress the fluctuation (LFV).

  However, in the present embodiment, the width direction dimension of the strip composite in the stacking direction replacement region is set to 1/3 or less of the width of the strip composite. Thereby, when the dimension in the width direction of the stacking direction switching region is made relatively small and viewed as the entire strip composite, it is possible to suppress the remaining torsional deformation in any direction when the product tire rolls. As a result, lateral force fluctuation (LFV) can be sufficiently suppressed, and as a result, the performance related to rolling resistance can be further enhanced.

  In addition, the said effect can be show | played to a higher level by making the width direction dimension of the strip composite of a lamination direction exchange area | region into 1/4 or less of the width | variety of a strip composite, It shall be 1/5 or less. Thus, the above effect can be achieved at an extremely high level.

(Additional form 2-3)
In the basic form 2 and the form obtained by adding at least one of the additional forms 2-1 and 2-2 to the basic form 2, in the vulcanization step, among the laminated regions of the two types of strips in plan view, It is preferable to use a mold in which no convex portion is formed on the surface corresponding to the region in which the stacking direction positions of the strips are switched (stacking direction switching region) (additional form 2-3).

  In the product tire, by using a mold that does not have protrusions on the surface corresponding to the stacking direction replacement region, in the tire radial direction outer region of the cord in the stacking direction replacement region to the region from the tread surface. A rubber layer can be sufficiently present. In the stacking direction replacement region, the distance between cords arranged in the tire radial direction is smaller than the distance between coats in other regions. However, by adopting the manufacturing method as described above, even if the tire surface is deformed, the stress applied in the deformation reaches the peripheral region of the cord in the stacking direction changing region in a considerably attenuated state. It becomes. For this reason, it is suppressed that stress is excessively applied to the peripheral region, and the occurrence of a failure in the peripheral region is suppressed, so that the durability performance can be further enhanced.

(Additional form 2-4)
In the basic mode 2 and the basic mode 2 in which at least one of the additional modes 2-1 to 2-3 is added, two types of the above-described strips may be alternately stacked (additional mode 2-4). preferable.

  In the present embodiment, among the specific methods for forming the strip composite, for example, an example in which the strip composite is formed through the state shown in FIG. That is, in the present embodiment, for example, as shown in FIG. 7A, first, the second strip 62 extending in the second direction with respect to the first strip 60 extending in the first direction. Are crossed once so that their positions are interchanged in the stacking direction. Next, as shown in FIG. 7C, the positions of the third strips 66 extending in the first direction with respect to the second strips 62 extending in the second direction are switched in the stacking direction. Cross once. Then, the above operation is repeated between the strip extending in the first direction and the strip extending in the second direction, and the region surrounded by the dotted line shown in FIG. As described above, a plurality of other strips are sequentially arranged.

  Thereby, according to the crossing aspect of the strip, the crossing aspect of the cord in the product tire is appropriately realized. For this reason, in the product tire, the uniformity in the tire width direction can be increased, and as a result, the performance relating to rolling resistance can be further improved.

  When forming the strip composite, the distance between the strips extending in the same direction (for example, the strips 60 and 66 in FIG. 7C) can be 0 mm or more and 10 mm or less. By setting the above interval to 0 mm or more, avoiding excessive use of the rubber material without causing a laminated portion between the strips extending in the same direction, reducing the weight, and performance related to rolling resistance. It can be further increased. Moreover, a pneumatic tire can be manufactured by making the said space | interval 10 mm or less, without generating the vulcanization failure resulting from the air confined between strips.

  In addition, the said effect can be show | played by a higher level by the said space | interval being 3 mm or less.

(Additional Form 2-5)
In the basic form 2 and the form in which at least one of the additional forms 2-1 to 2-4 is added to the basic form 2, two kinds of extending directions are different in at least one side in the tire width direction in a plan view. It is preferable to form the strip composite by changing the outermost position in the tire width direction of the strip (additional form 2-5).

  When the manufacturing method of the present embodiment is adopted, in the product tire, as shown in FIG. 3 (a), the distance between cords located on the outermost side in the tire width direction of the belt ply 30 is as shown in FIG. The distance between the cords of the belt ply 10 shown in FIG. For this reason, even if the stress applied to the tire surface reaches the vicinity of the outermost cord in the tire width direction, there is a sufficient rubber layer as a cushioning material between the cords located on the outermost side in the tire width direction. The occurrence of a failure in the vicinity of the cord is suppressed, and the durability performance can be further enhanced.

  A belt in which the tire size is 195 / 65R15, and the first cord and the second cord are crossed once so that the positions in the tire radial direction are interchanged and continuously dotted in the tire width direction in the tire meridional section view. Pneumatic tires of Examples 1 to 5 including a ply (for example, a belt ply shown in FIG. 1B) were manufactured. Various conditions regarding the detailed structure of the pneumatic tires of Examples 1 to 5 are as shown in Table 1 below.

  On the other hand, the tire size is 195 / 65R15, and the first cord and the second cord are continuously scattered in the tire width direction without changing the tire radial direction position in the tire meridional section view. A conventional pneumatic tire consisting only of a belt ply was manufactured.

  Each of the test tires of Examples 1 to 5 and the conventional example manufactured as described above was mounted on a rim of size 6J, and the performance and durability performance regarding the rolling resistance were evaluated according to the following procedure.

(Performance related to rolling resistance)
The rolling resistance of each test tire was measured by a force method based on ISO 28580. And based on this measurement result, the index evaluation which made the conventional example the reference | standard (100) was performed. This evaluation shows that the larger the index, the higher the performance related to rolling resistance.

(Durability)
A normal load was applied to each rim set tire, a normal load was applied, and a slalom running test was performed using a drum having a diameter of 1700 mm and changing the slip angle within a range of ± 5 °. And the travel distance when the tire broke was measured. And based on this measurement result, the index evaluation which made the conventional example the reference | standard (100) was performed. This evaluation indicates that the larger the index, the higher the durability performance.
These results are also shown in Table 1.

  The normal internal pressure means the “maximum air pressure” specified by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. . Furthermore, the normal load means the “maximum load capacity” specified by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “LOAD CAPACITY” specified by ETRTO. Say.

  According to Table 1, the pneumatic tires of Examples 1 to 5 belonging to the technical scope of the present invention (with improvements made to the arrangement of two types of cords constituting the belt layer) However, it can be seen that the performance relating to the rolling resistance is improved without impairing the durability performance as compared with the conventional pneumatic tire which does not belong to the technical scope of the present invention.

10, 20, 30, 40, 50 Belt ply 12, 12a, 12b1, 12b2, 12c1, 12c2 First cord 14, 14a, 14b1, 14b2, 14c1, 14c2 Second cord 16 Rubber 60 First strip 62 Second strip 64 , 66 Third strip 70 Strip composite 72 a, 72 b Strip B 1, B 2, B 3, B 4, B 5, B 6 Belt layer C Tire width direction region CL Tire equatorial plane E 1, E 2 Extending direction both ends G of strip composite 70 G Maximum Rubber gauge OR Laminated area P1, P2, P3, P4 Point S, S1, S2, S3 Strip SC, SC1, SC2, SC3 Code SG Rubber material X1, X2 Arrow (twist direction)

Claims (11)

A carcass layer formed between a pair of bead portions; a belt layer made of at least one belt ply formed on the tread portion on the outer side in the tire radial direction of the carcass layer; and on the outer side in the tire radial direction of the belt layer. With tread rubber formed,
In a plan view, at least one of the belt plies has a plurality of first cords extending at equal intervals in the same direction, and a plurality of first cords inclined with respect to the first cord and extending at equal intervals in the same direction. In a pneumatic tire including a second cord and a rubber covering the first cord and the second cord,
In the tire meridian cross-sectional view, the first cord and the second cord are crossed once so that the positions in the tire radial direction are interchanged, and are continuously scattered in the tire width direction. Enter tire.   The line segment which connected the overlapping parts adjacent to a tire peripheral direction among the overlapping parts of the said 1st code | cord | chord and the said 2nd code by plane perspective is parallel to a tire peripheral direction. Pneumatic tire.   The land portion is formed on the outer side in the tire radial direction of the tire width direction region where the distance between the first cord and the second cord is the smallest in the tire meridional section until reaching the tread surface. Or the pneumatic tire of 2.   4. The maximum rubber gauge between the first cord and the second cord at the same position in the tire width direction in a tire meridional cross-sectional view is 0.2 mm or more and 2.5 mm or less. The pneumatic tire according to item.   5. The tire according to claim 1, wherein the outermost position in the tire width direction of the first cord is different from the outermost position in the tire width direction of the second cord on at least one side in the tire width direction in a tire meridional cross-sectional view. The pneumatic tire according to claim 1. A method for manufacturing a pneumatic tire including a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and an inspection step after vulcanization,
In the process of processing the tire material,
Coating at least one cord with rubber to form a plurality of strips;
Two types of strips extending in different directions are crossed once so that the positions in the laminating direction are interchanged to form a strip composite as a material for the belt layer.
A method for manufacturing a pneumatic tire.   The strip composite is formed so that the line segment connecting the two ends of the strip composite in the stacking region of the two types of strips is parallel to the extending direction of the strip composite in plan view. The manufacturing method of the pneumatic tire of Claim 6.   In a plan view, the width direction dimension of the strip composite in an area where the stacking direction positions of the strips are interchanged among the two types of the laminated areas of the strips is set to 1/3 or less of the width of the strip composite. The manufacturing method of the pneumatic tire of Claim 6 or 7.   In the vulcanization step, a mold having no convex portion formed on the surface corresponding to a region where the stacking direction positions of the strips are interchanged among the two types of the layered regions of the strips is used in plan view. The method for manufacturing a pneumatic tire according to any one of claims 6 to 8.   The method for manufacturing a pneumatic tire according to any one of claims 6 to 9, wherein the two kinds of the strips are alternately laminated.   11. The strip composite according to claim 6, wherein the strip composite is formed by differentiating the outermost positions in the tire width direction of the two types of strips having different extending directions on at least one side in the tire width direction in a plan view. The manufacturing method of the pneumatic tire of Claim 1.

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