JP4402940B2 - Method for joining side edge portions of cord ply, and method for producing tire using joining ply produced thereby - Google Patents

Description

The present invention relates to a method for joining side edges of a cord ply that can make the distance between cord centers in a cord ply joined by a zipper joint uniform, and a method for manufacturing a tire using the joint ply produced thereby .

  For example, as shown in FIG. 6, the carcass ply a of the tire is formed by using an unvulcanized rubberized fabric c in which both sides of the cord array body b are rubber-topped as a raw fabric.

  Specifically, the rubberized fabric c is cut at a desired angle θ (about 90 ° for a radial tire) with respect to the length direction and a length corresponding to the width of the carcass ply, and each cut piece c1 is cut into the cut piece c1. The splice e is formed by sequentially joining the side edges on the non-cut side. Then, the joint ply e is cut into a predetermined size, wound on a forming drum, and the carcass plies a are formed in a cylindrical shape by joining the circumferential ends thereof.

  At this time, the joining between the cut pieces c1 and c1 and the joining between the circumferential ends of the cut ply e are fixed as shown in FIG. This is performed by a so-called overlap joint that overlaps and crimps the gaps. However, in the joint portion j1 of such an overlap joint, since the cords f overlap each other, the elongation of the cord f when filling the tire internal pressure is reduced unevenly, and the joint portion j1 is recessed in a band shape. There is a problem that joint dents occur and the tire appearance is remarkably impaired.

  Therefore, in recent years, in order to suppress the joint dent, as shown in FIG. 7B, a zipper joint has been proposed in which two piece bodies g having a cone surface are used and the end edge portions d and d are butted against each other. (See Patent Documents 1 and 2).

JP-A-9-70902 JP 2001-105508 A

  However, in this zipper joint, the urging force F in the abutting direction acts strongly in order to ensure the necessary bonding strength. As a result, the cord center distance ps of 2 to 5 cords fs arranged on the end edge side is gradually smaller than the cord center distance pc of the other cords fc and toward the side edge d. The distance between the cord centers peculiar to this zipper joint occurs. Therefore, although the joint dent is improved as compared with the overlap joint, a satisfactory improvement effect has not been obtained.

Accordingly, the present invention provides a method for joining side edges of a cord ply that can suppress the non-uniformity of the cord center distance peculiar to the zipper joint, and can sufficiently exhibit the effect of improving the joint dent, and the joining ply produced thereby. An object of the present invention is to provide a method for manufacturing a tire using the tire .

In order to achieve the above-mentioned object, the invention of claim 1 of the present application is characterized in that an unvulcanized cord ply in which a cord array in which steel cords are arranged in parallel is covered with a topping rubber is provided on each side edge along the steel cord. A method for joining side edges of cord plies to be joined at
The steel cord is arranged at a central steel cord having a constant cord center distance Pc between adjacent cords and a side edge portion thereof, and the cord center distance Ps is larger than the cord center distance Pc. It consists of 2-5 steel cords that gradually increase toward the side edge,
By joining the side edge portions with a zipper joint using two pieces having a cone surface around the rotation axis, a joining ply having a uniform distance between cord centers after joining is obtained.

  According to a second aspect of the present invention, the cord center distance Ps of the steel cord on the side increases in proportion to the side edge portion, and the outermost cord center distance among the cord center distances Ps. Psmax is characterized by being 1.05 to 1.50 times the distance Pc between cord centers of the central steel cord.

  In the invention of claim 3, the length from the steel cord on the outermost side to the side edge of the topping rubber at the one side edge of the cord plies to be joined to each other, and the side edge on the other side The total length L with respect to the length is not less than the cord center distance Psmax and is 1.05 to 1.50 times the cord center distance Pc of the central steel cord.

  According to a fourth aspect of the present invention, the zipper joint approaches the maximum diameter portion of the cone surface of the piece body, and the rotation at an angle at which one bus bar of each of the two piece bodies is parallel to the surface of the cord ply. It is characterized by being joined using a joining means that is arranged with the shaft centers crossed and that is positioned between the side edges of the cord plies to be joined between the two pieces.

The invention of claim 5 is a method of manufacturing a tire characterized by Rukoto using a bonding ply produced by any of the 請 Motomeko 1-4 carcass ply.

  Since the present invention is configured as described above, it is possible to suppress the non-uniform distance between the cord centers peculiar to the zipper joint, and to improve the joint dent to a sufficiently satisfactory level.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of a tire in which a joining ply joined by the method for joining side edges of a cord ply of the present invention is used as a carcass ply.

  In FIG. 1, a tire 1 is a heavy-duty tire, and includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, an inside of the tread portion 2, and a radius of the carcass 6. It comprises at least a belt layer 7 disposed on the outer side in the direction.

  The belt layer 7 is formed of two or more belt plies (three or more in the case of heavy load tires) using a belt cord. In this example, the belt layer 7 includes a first belt ply 7A on the innermost side in the radial direction in which steel cords are arranged at an angle of 60 ± 15 ° with respect to the tire circumferential direction, and 10 to 10 with respect to the tire circumferential direction. A case of a four-sheet structure with second to fourth belt plies 7B to 7D arranged at a small angle of 35 ° is illustrated. The belt plies 7 </ b> A to 7 </ b> D are provided with one or more places where the belt cords cross each other between the plies, and are superposed to enhance belt rigidity and reinforce the tread portion 2 with a tagging effect.

  Further, the carcass 6 is formed of one or more carcass plies 6A, in this example, one carcass ply 6A in which carcass cords made of steel cords are arranged at an angle of 70 to 90 ° with respect to the tire circumferential direction. The carcass ply 6A includes a series of ply turn-up portions 6b that are turned back from the inside in the tire axial direction around the bead core 5 on both sides of the ply main body portion 6a straddling the bead cores 5 and 5. A bead apex rubber 8 for bead reinforcement extending radially outward from the bead core 5 is disposed between the main body portion 6a and the folded portion 6b.

  And the said carcass ply 6A is formed using the joining ply 10 joined by the side edge part joining method of the cord ply of this invention.

  As shown in FIG. 2, the cord ply joining method uses an unvulcanized cord ply 13 in which steel cords 11 (carcass cords) arranged in parallel are covered with topping rubber G on both sides of the cord array body 12. The side edges E and E of the cord ply 13 are butted together by a zipper joint.

  At this time, the steel cord 11 of the cord ply 13 has a central steel cord 11c having a constant cord center distance Pc between adjacent cords and a side edge portion E side as shown in a cross section in FIG. The steel cords 11s are arranged on the two to five sides, and the cord center distance Ps is larger than the cord center distance Pc and gradually increases toward the side edge E.

  In other words, the cord ply 13 is composed of the central region Yc and the side regions Ys of the side edges E thereof, and the steel cord 11c arranged in the central region Yc is arranged with a constant cord center distance Pc. ing. Further, 2 to 5 steel cords 11s are arranged in the side region Ys, and the cord center distance Ps of the steel cord 11s is larger than the cord center distance Pc, and further toward the side edge portion E. Gradually increasing.

  By adopting the cord ply 13 having such a cord arrangement, it is possible to cancel the non-uniformity of the cord center distance peculiar to the zipper joint, and as shown in FIG. 4 the cord center distance Psj after joining, It becomes possible to obtain the joint ply 10 having a uniform code arrangement in which the variation with respect to the code center distance Pc is suppressed to 5% or less.

  Therefore, as shown in an enlarged view in FIG. 2, it is preferable to increase the inter-cord distance Ps of the steel cord 11s on the side in a directly proportional manner toward the side edge E, that is, to keep the increase rate constant. . At this time, the maximum outermost cord center distance Psmax among the cord center distances Ps is in a range of 1.05 to 1.50 times the cord center distance Pc of the central steel cord, A range of 1.2 to 1.5 times is preferable. Further, the length L1 from the center of the steel cord 11s1 on the most end side to the side edge of the topping rubber G in the side edge E1 on one side of the cord plies 13 to be joined to each other, and the side edge on the other side The total length L (= L1 + L2) of the length L2 in E2 is not less than the cord center distance Psmax and is 1.05 to 1.50 times the cord center distance Pc of the central steel cord 11c. It is also preferable.

  If the increase in the cord center distance Ps is not directly proportional, or if the ratio Psmax / Pc is out of the range of 1.05-1.50, or the length L is smaller than the cord center distance Psmax. If the ratio L / Pc is out of the range of 1.05 to 1.50, the cord center distance Psj after joining tends to exceed 5% variation. It becomes a trend.

  In the cord ply 13, the cord structure of the steel cord 11, the cord center distance Pc in the central region Yc, and the like can be appropriately set according to the required performance of the carcass 6. Similar to a typical cord ply, for example, the cord center distance Pc is 2.50 mm to 0.83 mm (20 to 60 cords / 5 cm in terms of driving density), and the steel cord 11 has a diameter of 0.50 to 1.40. The range can be suitably employed.

  Next, the zipper joint is performed by using known joining means 21 including two pieces 20 having cone surfaces 20S around the rotation axis N as schematically shown in FIG.

  Specifically, each piece body 20 has a rotation axis N at an angle at which the largest diameter portion 22 of the cone surface 20S is brought close to each other and one bus bar X forming each cone surface 20S is parallel to the surface of the cord ply 13. Are arranged. Then, the middle of the two piece bodies 20 is positioned at the center between the side edges E and E of the cord plies to be joined, and each piece body 20 is rotated. Thereby, each side area | region Ys can be urged | biased in the abutting direction, between the side edge parts E and E can be strongly pressed, and it can join firmly. Then, the non-uniformity of the cord center distance caused by the urging force in the abutting direction can be suppressed by using the cord ply 13 described above.

  In the zipper joint, the urging force in the abutting direction causes a thick portion Q such that a topping rubber G swells in a substantially V shape as shown in FIG. It tends to cause unevenness. Therefore, after the zipper joint, it is preferable for the joint dent to be further improved by subjecting the joint to a rolling process with a roller to suppress uneven thickness.

  Such a method for joining the side edges of the cord ply according to the present invention is employed to join the joint ply e of a fixed size wound on the forming drum at the circumferential end as shown in FIG. You can also In such a case, the cord ply 13 corresponds to the joint ply e of the fixed size cut, and the joining ply 10 corresponds to the carcass ply 6A.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  A tire using a joining ply joined by the joining method of the present invention as a carcass ply was manufactured as a trial, and a joint dent depth h of the prototype tire was measured and compared with a conventional tire. Further, the variation range of the distance between the cord centers in the bonding ply is indicated by an index where the distance Pc between the cord centers is 1. The joint dent depth h is an average value of five prototype tires.

  The specifications of the cord ply used for the joining ply are as shown in Table 1, and the cord center distances Ps1, Ps2, and Ps3 in the table mean the cord center distances from the outermost side. The cord center distances Ps1, Ps2, Ps3 and the length L are indicated by indices with the cord center distance Pc being 1.

  As shown in the table, it can be confirmed that the distance between the cord centers can be made uniform and the joint dent can be suppressed by the joining method of the present invention.

It is sectional drawing which shows one Example of the tire which used the joining ply joined by the side edge part joining method of the cord ply of this invention for the carcass ply. It is sectional drawing which expands and shows the side edge part of a cord ply. It is sectional drawing which expands and shows the whole cord ply. It is sectional drawing which expands and shows the junction part of a joining ply. It is a diagram which shows the joining means of a zipper joint schematically. It is a diagram explaining the formation method of the carcass ply of the conventional tire. (A), (B) is sectional drawing of the joint part explaining the problem of a prior art.

Explanation of symbols

10 Joining ply 11 Steel cord 11c Steel cord 11s in the center Steel cord 12 Cord arrangement body 13 Cord ply 20 Top body 20S Cone surface E Side edge G Topping rubber

Claims (5)

A cord ply side edge joining method for joining unvulcanized cord plies in which a cord array in which steel cords are arranged in parallel are covered with a topping rubber at each side edge along the steel cord,
The steel cord is arranged at a central steel cord having a constant cord center distance Pc between adjacent cords and a side edge portion thereof, and the cord center distance Ps is larger than the cord center distance Pc. It consists of 2-5 steel cords that gradually increase toward the side edge,
A cord ply characterized in that a joining ply having a uniform distance between cord centers after joining is obtained by joining the side edge portions with a zipper joint using two pieces having a cone surface around the rotation axis. Side edge joining method.   The cord center distance Ps of the steel cord on the side increases in direct proportion toward the side edge, and the outermost cord center distance Psmax among the cord center distances Ps is equal to the central steel cord. The cord ply side edge portion joining method according to claim 1, wherein the cord center distance Pc is 1.05 to 1.50 times.   The total length of the length from the center of the steel cord on the outermost side to the side edge of the topping rubber at the one side edge of the cord plies to be joined to each other and the length at the other side edge The side edge portion of the cord ply according to claim 2, wherein L is not less than the cord center distance Psmax and is 1.05-1.50 times the cord center distance Pc of the central steel cord. Joining method.   The zipper joint is arranged so that the maximum diameter portion of the cone surface of the piece body is brought close to each other and the rotation axis is intersected at an angle at which one bus bar of each of the two piece bodies is parallel to the surface of the cord ply. The cord ply according to any one of claims 1 to 3, wherein the cord ply is joined using a joining means positioned between the side edges of the cord plies to be joined. Side edge joining method. Method of manufacturing a tire characterized by Rukoto using a bonding ply produced by any one of claims 1 to 4 as a carcass ply.

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