JP4721481B2 - Pneumatic radial tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, pneumatic radial tires, inter alia, the carcass ply cord, relates radial tire comprising a continuous coding repeating reciprocation between each other pair of bead portions sequentially, in particular, the automatic molding of the green tire It is possible to achieve excellent bead durability.
[0002]
[Prior art]
For carcass plies that reinforce the pneumatic tire from the tread to the pair of sidewalls and beads, organic fiber cords such as nylon cord and polyester cord, or inorganic fiber cords such as carbon fiber cord and steel cord Is widely used in general.
[0003]
A carcass ply formed by arranging such a ply cord in the radial direction usually has a winding part that is wound around the bead core arranged in the bead part from the inner side to the outer side in the tire radial direction, Since each ply cord has a cut end at the radially outer end at the winding portion, in the load rolling of a tire having such a radial carcass ply, the outer end portion of the winding portion is subjected to shearing in the tire radial direction and the circumferential direction. When distortion occurs, there is a problem that separation tends to occur at the outer end portion where the cut end of the ply cord that is difficult to adhere to rubber is located.
On the other hand, a tire having such a carcass ply structure provided with a winding part brings about an increase in the number of green tire molding operations due to the presence of the winding part, and the winding part automates the tire molding work. There was also a problem that could interfere.
[0004]
Therefore, in recent years, a pneumatic radial tire suitable for automatic molding, including a carcass ply that does not have a winding part has been proposed, and a method for manufacturing a pneumatic tire suitable for automatic molding has been proposed.
[0005]
For example, in Japanese Patent Laid-Open No. 6-171306, a radial carcass ply cord is a reciprocating arrangement of cords that are continuous between a pair of bead portions. A pneumatic radial tire in which a carcass is fixed by being sandwiched between bead cores through the hard rubber layer described above, and Japanese Patent Laid-Open No. 9-155991 discloses a cord of a radial carcass ply between a pair of bead portions. In regard to the radial ply tire similar to the above publication in terms of the reciprocating arrangement of the continuous cords, the folded portion of the reciprocating cord is wound around a pair of bead cores formed by winding a twisted cord, as in the conventional tire, A method of manufacturing a pneumatic tire wound up from the inner side to the outer side in the tire radial direction and a tire manufactured by this method are respectively provided. Any of these disclosed technologies facilitates automatic molding of a green tire and effectively prevents the occurrence of separation in that the bead portion does not have a cut end of a ply cord. Can do.
[0006]
[Problems to be solved by the invention]
However, in the pneumatic radial tire disclosed in the former publication, since the carcass is fixed only by sandwiching the folded portion of the reciprocating cord between the bead cores through the hard rubber layer, with increasing load rolling distance of the tire, the carcass ply cord, pull out phenomenon can not ensure a sufficient bead portion durability supposed to proceed from between the bead core.
[0007]
On the other hand, in the pneumatic tire disclosed in the latter publication, the carcass ply cord is pulled out as described above by forming a winding portion wound around the bead core at the reciprocating folded portion of the carcass ply cord. The bead core is composed of a stranded wire cord, and only one bead core is provided in each bead portion, so that the bead portion rigidity is insufficient. Because the bead core is stretched along the circumference and the bead core is less constrained to the carcass ply cord, the carcass ply cord is pulled out, resulting in insufficient durability of the bead portion. The problem to do will remain.
[0008]
An object of the present invention is to solve such problems of the prior art, and the object of the present invention is to provide a bead portion under a carcass ply structure that facilitates automatic molding of a green tire. Is to provide a pneumatic radial tire that sufficiently secures the required strength and rigidity, effectively prevents the carcass ply cord from being pulled out, and greatly improves the durability of the bead portion.
[0009]
[Means for Solving the Problems]
The pneumatic radial tire according to the present invention includes a tread portion, a pair of sidewall portions that are continuous with the side portions of the tread portion, and a bead portion that is continuous inward in the radial direction of the sidewall portion. Each bead reinforcing layer disposed in the circumferential direction and a carcass ply extending in a toroidal manner to reinforce each of the above-mentioned parts, and reinforcing the carcass ply with each bead reinforcing layer. It is constituted by a continuous cord that repeats reciprocation across the layers sequentially via a turn-back portion positioned along the circumference of the bead portion, and two or more carcass plies are arranged, and rubber is provided between the carcass plies. The folding portion of the continuous cord constituting the carcass ply, which is located on the inner side of the tire, with the seat interposed therebetween is located on the outer side of the tire. See write suppressed directly by the phloem, the bead reinforcing layer, across the two or more carcass plies, as well as arranged on both the inside and the outside in the width direction of the tire, disposed therebetween in each of the carcass ply It will be.
[0010]
More preferably, a rubber sheet is interposed over the entire width of the carcass ply. The entire width of the carcass ply in this case refers to periphery width with the tire cross-section, if there is a difference in Bae Riferi width between adjacent two of the carcass plies, the rubber sheet is narrow side carcass ply or It is assumed that the peripheral width is as follows.
[0011]
In such a pneumatic radial tire, each carcass ply has a rubber between them, regardless of whether or not the continuous cord is pre-rubber coated by heat and pressure during vulcanization molding of the green tire. Fully embedded in the seat, this greatly increases the contact area of the continuous cord with the rubber sheet over its entire length, so that both carcass plies can extend over them and at any position in the circumferential direction. Will be constrained almost evenly, so that even if the tire rolls over a long period of time, it will effectively prevent the continuous cord from being pulled out in the entire circumferential direction, greatly improving the durability of the bead part. it can.
[0012]
This is because the bead reinforcement layer is disposed on both the inner and outer sides in the tire width direction with two or more carcass plies interposed therebetween, and is disposed between the carcass plies so that the bead reinforcement layer is This is more effective when the restraining force of the carcass ply is increased.
[0013]
By the way, in this case, it is preferable to interpose another rubber sheet on the side of the bead reinforcement layer disposed between the carcass plies and not adjacent to the rubber sheet. According to this, each carcass ply is connected to the bead. It can be restrained more advantageously with the reinforcing layer.
[0014]
Here, it is preferable that the thickness of the rubber sheet is in the range of 0.3 to 1.0 mm in order to appropriately fill the carcass ply and the bead reinforcing layer. That is, if the thickness is less than 0.3 mm, it is difficult to ensure a sufficient amount of embedding, while if it exceeds 1.0 mm, the material yield decreases and the tire weight and cost increase.
[0015]
The 100% modulus of the rubber sheet is preferably 7.0 to 9.5 MPa in order to secure the adhesive strength of the bead reinforcement layer and the retention strength of the carcass ply.
[0016]
Further, in order to more sufficiently restrain the carcass ply cord, the folded portion of the continuous cord is positioned inward in the tire radial direction from the bead reinforcing layer, and the folded portion of the continuous cord is arranged around the bead reinforcing layer. It is preferable to rewind from the inner side to the outer side in the tire radial direction.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the drawings.
FIG. 1 is a perspective view showing a basic form of the present invention, with a part thereof being broken and removed in the state of a green tire molded on a mold.
In the figure, 1 is a portion corresponding to a tread portion of a product tire after vulcanization molding, 2 is a product tire, a portion corresponding to a sidewall portion continuous to each side portion of the tread portion, and 3 is a In the same tire, portions corresponding to bead portions continuous inward in the radial direction of the sidewall portion are shown. Here, for convenience of explanation, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. Will be called.
[0018]
In this green tire, for example, one rigid core having an outer surface shape corresponding to the inner surface shape of a product tire is used as a molding die, and then the inner rubber layer 4 as the innermost layer is used to form the respective parts 1, 2, Up to 3 can be formed by lamination molding.
[0019]
As shown in the figure, at the position corresponding to each bead portion 3, for example, a cord made of a single wire or a stranded wire of steel is wound around the bead portion circumference in a spiral shape on the outside of the inner rubber layer 4. The innermost bead reinforcing layer 5 is provided, and at least one continuous cord 6, for example, a continuous inorganic fiber cord or a continuous organic fiber cord is provided on the outer side of the bead reinforcing layer 5. The carcass ply 8 on the inner layer side is arranged by repeating the reciprocation in the direction to be repeated sequentially over the entire circumference via the turn-back portion 7 positioned along the circumference of the bead portion.
Here, the reciprocating extension portions of the continuous cord 6 are positioned at substantially equal pitches over the entire circumference, and the folded portions 7 thereof are positioned inward in the tire radial direction from the bead reinforcing layer 5.
[0020]
Further, on the outer side of the inner layer side carcass ply 8, a rubber sheet 9 having a thickness of preferably 0.3 to 1.0 mm and having a 100% modulus within the product tire of 7.0 to 9.5 MPa is provided on the carcass. The rubber sheet 9 is disposed over the entire width of the ply 8, and covers from one folded portion 7 to the other folded portion 7 of the carcass ply 8. Further, on the outer side of the rubber sheet 9, an outer layer side carcass ply 12 configured by reciprocating a continuous cord 10 made of inorganic or organic fibers through a turn-back portion 11 in the same manner as in the previous case is disposed. The outermost bead reinforcing layer 13 configured in the same manner as the innermost bead reinforcing layer 5 is disposed outside the carcass ply 12.
[0021]
In this case, the turn-up portion 11 of the outer layer side carcass ply 12 may be positioned at a radial position equal to that of the inner layer side carcass ply 8, and the outermost bead reinforcement layer 13 has a radius equal to that of the innermost bead reinforcement layer 5. It may be arranged in a directional position.
[0022]
The reciprocating pitch of the continuous cords 6 and 10 of the inner and outer carcass plies 8 and 12 can be different from each other as well as the same pitch. In addition to overlapping and positioning, they can also be positioned alternately.
Further, a belt 14 that contributes to reinforcement of the tread portion 1 is disposed outside the crown portion of the outer layer side carcass ply 12.
[0023]
In the green tire configured as described above, and in the pneumatic radial tire as the product tire formed by vulcanizing it, each carcass ply is based on the deformation displacement of the rubber sheet 9 accompanying the vulcanization molding. The continuous cords 6 and 10 of 8 and 12 are sufficiently embedded in the rubber sheet 9 over the entire circumference, whereby the carcass plies 8 and 12 are sandwiched by the bead reinforcing layers 5 and 13. Combined with the action, the relative displacement of the continuous cords 6 and 10 is mutually restrained via the rubber sheet 9, so that the withdrawal of the continuous cords 6 and 10 is sufficient even when the tire is rolling for a long time. Will be prevented.
[0024]
FIG. 2 is a view similar to FIG. 1 showing another basic form of the present invention. This is because the reciprocating pitch of the continuous cords 6 and 10 constituting the carcass plies 8 and 12 on both the inner and outer sides is three times the required arrangement pitch of the continuous cords 6 and 10, and the mold is rotated three times. In the meantime, the reciprocation of the continuous cords 6 and 10 is performed with a phase difference of 1/3 pitch in the circumferential direction, and the folded portions 7 and 7 located inside the continuous cords 6 and 10 are performed. 11 is held by the folded portions 7 and 11 located outside, and the outermost bead reinforcing layer 13 is wound around the inner and outer three rows to form a winding structure of the carcass plies 8 and 12 by the bead reinforcing layers 5 and 13. The holding power is increased.
[0025]
Here, it goes without saying that the number of columns of the outermost bead reinforcing layer 13 can be appropriately increased or decreased as required.
Further, in this case, in order to maintain the overlapping state of the folded portions 7 and 11 that are located on the inside and outside, the continuous cord is preliminarily coated with rubber and the adhesive strength between the coating rubbers is used. However, if the thickness of the coating rubber is too thick, the resistance at the yarn path for feeding out the continuous cord increases, making it difficult to feed the cord smoothly. It is advantageous to do so.
[0026]
Therefore, according to this basic form, it is possible to more effectively prevent the continuous cords 6 and 10 from being pulled out under the above-described restraining of the folded portions 7 and 11 and an increase in the carcass ply pinching force.
[0027]
FIG. 3 is a schematic cross-sectional view of an essential part showing the embodiment of the present invention on one bead side, which is made of, for example, a single steel wire or a stranded wire between the carcass plies 8 and 12 on both inner and outer sides. An intermediate bead reinforcing layer 15 formed by winding a cord in a spiral shape along the circumference of the bead portion is provided. Here, the intermediate bead reinforcing layer 15 is positioned outside the rubber sheet 9 as shown in FIG. 3A, and also inside the rubber sheet 9 as shown in FIG. 3B. It can also be positioned.
[0028]
In this case, as shown in FIGS. 4 (a) and 4 (b), at least the bead is formed in the portion where the intermediate bead reinforcing layer 15 and the carcass ply directly face each other without the rubber sheet 9 interposed therebetween. It is preferable to interpose another rubber sheet 16 in the radial region corresponding to the reinforcing layer 15.
[0029]
According to this, each carcass ply 8, 12 is not only sandwiched by the bead reinforcing layer 15, but also based on the bead reinforcing layer 15 being embedded in the rubber sheets 9, 16, not only by their mutual, Since the displacement is also constrained by the bead reinforcing layer 15, it is possible to more effectively prevent the continuous cords 6 and 10 from being pulled out.
[0030]
This is particularly noticeable when the cord turn-up portions 7 and 11 of the carcass plies 8 and 12 are wound from the inner side to the outer side in the tire radial direction at least around the adjacent bead reinforcing layer. In addition, it is advantageous to perform such rewinding toward the outside rather than toward the inside when considering the moldability of the tire.
[0031]
FIG. 5 is a schematic cross-sectional view of an essential part showing still another basic form of the present invention, in which the number of carcass plies is three, the bead reinforcement layers are three layers, and the intermediate bead reinforcement layers. The arrangement of 15 is variously changed. Further, the main part schematic cross-sectional view of FIG. 6 showing the modified example of FIG. 5 is such that rubber sheets are interposed on both sides of the intermediate bead reinforcing layer 15. Also by these forms state, under the action of the rubber sheet can provide the same effect as was mentioned earlier.
[0032]
5 and 6, the bead reinforcement layer can be arranged between all the carcass plies so that the number of layers can be four. According to this, the binding force on the carcass ply can be increased. Can be further increased.
[0033]
Although the present invention has been described based on the drawings, the number of carcass plies can be four or more.
[0034]
【Example】
When the tire having the structure shown in FIG. 1 and the comparative example tire having the structure shown in FIG. In FIG. 1 , continuous cord pull-out occurred at a filling pressure of 1.7 MPa, whereas in the tire having the structure shown in FIG. 1, cord pull-out was not observed until 2.5 MPa.
[0035]
【The invention's effect】
As is apparent from the above description, according to the present invention, the automatic molding of the green tire is facilitated, and with the rubber sheet interposed between the carcass plies, by increasing the binding force between the carcass plies, It is possible to effectively prevent the continuous cord from being pulled out and greatly improve the durability of the bead portion.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a basic configuration of the present invention with a part thereof removed by breaking.
FIG. 2 is a view similar to FIG. 1, showing another basic form of the present invention .
FIG. 3 is a schematic cross-sectional view of an essential part showing an embodiment of the present invention.
4 is a view similar to FIG. 3, showing a modification of FIG.
FIG. 5 is a schematic cross-sectional view of an essential part showing still another basic form of the present invention.
6 is a view similar to FIG. 5 showing a modification of FIG.
DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Inner surface rubber layer 5,13,15 Bead reinforcement layer 6,10 Continuous cord 7,11 Folded part 8,12 Carcass ply 9,16 Rubber sheet 14 Belt

Claims (7)

A tread portion, a pair of sidewall portions that are continuous with the side portions of the tread portion, and a bead portion that is continuous inward in the radial direction of the sidewall portion, and is disposed in each bead portion in the circumferential direction. Each continuous bead reinforcing layer and a carcass ply extending in a toroidal manner to reinforce each of the above-described parts are provided between the bead reinforcing layers. In a pneumatic radial tire constituted by a continuous cord that repeats sequentially through a turn-back portion positioned along,
Two or more carcass plies are disposed, a rubber sheet is interposed between the carcass plies, and the folded portion of the continuous cord constituting the carcass ply located on the inner side of the tire is positioned on the outer side of the tire. see write suppressed directly by the folded portion, the bead reinforcing layer, across the two or more carcass plies, as well as arranged on both the inside and the outside in the width direction of the tire, disposed therebetween in each of the carcass ply Pneumatic radial tire.   The pneumatic radial tire according to claim 1, wherein a rubber sheet is interposed over the entire width of the carcass ply. 3. The pneumatic radial tire according to claim 1, wherein another rubber sheet is interposed on a side surface of the bead reinforcing layer disposed between the carcass plies that is not adjacent to the rubber sheet. The pneumatic radial tire according to any one of claims 1 to 3, wherein the rubber sheet has a thickness of 0.3 to 1.0 mm. The pneumatic radial tire according to any one of claims 1 to 4, wherein the rubber sheet has a 100% modulus of 7.0 to 9.5 MPa. The pneumatic radial tire according to any one of claims 1 to 5, wherein the folded portion of the continuous cord is positioned inward in the tire radial direction from the bead reinforcing layer. The pneumatic radial tire according to any one of claims 1 to 6, wherein the folded portion of the continuous cord is wound around the bead reinforcing layer from the inner side to the outer side in the tire radial direction.

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