JP2005088793A - Bead core of heavy load, pneumatic radial-ply tire - Google Patents

Bead core of heavy load, pneumatic radial-ply tire Download PDF

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JP2005088793A
JP2005088793A JP2003326458A JP2003326458A JP2005088793A JP 2005088793 A JP2005088793 A JP 2005088793A JP 2003326458 A JP2003326458 A JP 2003326458A JP 2003326458 A JP2003326458 A JP 2003326458A JP 2005088793 A JP2005088793 A JP 2005088793A
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bead core
pneumatic radial
layer
heavy
cross
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Takeshi Takahashi
健 高橋
Toru Moriki
徹 森木
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Yokohama Rubber Co Ltd
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Yokohama Rubber Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a bead core for a heavy load, pneumatic radial-ply tire capable of decreasing a ruptural failure due to fretting of a carcass code and a tire failure resulting from an air sump by heightening the adhesion of a carcass layer to the bead core. <P>SOLUTION: The bead core 1 of the heavy load, pneumatic radial-ply tire consists of a bundle R of metal wires formed by winding a single metal wire S in layers in such a way that the arrangement pitch is dislocated at 1/2 intervals between the layers from the inner to the outer, wherein the section at least on the inside from the section center of the bead core 1 is shaped as consisting of a bottom edge member R1 parallel with the axial direction X of the bead core 1, intermediate side edge members R2 on the left and right perpendicular to the axial direction X, and diagonal members R3 and R4 in which the tangent angle of the two edge members tying the left and right intermediate side members R2 to the bottom edge member R1 is obtuse. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は重荷重用空気入りラジアルタイヤのビードコアに関し、さらに詳しくは、カーカス層のビードコアに対する折り返し部の密着性を高めることによりタイヤ故障の低減を可能にした重荷重用空気入りラジアルタイヤのビードコアに関する。   The present invention relates to a bead core for a heavy-duty pneumatic radial tire, and more particularly to a bead core for a heavy-duty pneumatic radial tire that can reduce tire failure by improving the adhesion of the folded portion of the carcass layer to the bead core.

重荷重用空気入りラジアルタイヤのビード部に埋設するビードコアには、古くから一本のスチール芯線とその周囲を螺旋状に取り巻く複数層のケーブル線とからなるケーブルビードが使用されてきた。しかし、かかるケーブルビードは生産性が悪くコスト高となることから、これに代わって、筒状の台座の周囲に１本の金属線を連続して螺旋状に巻いて列状に並べ、これを内層から外層へと多層に巻き重ねて１本巻きのビードコアにしたものが使用されるようになってきた。   For a bead core embedded in a bead portion of a heavy duty pneumatic radial tire, a cable bead including a single steel core wire and a plurality of layers of cable wires spirally surrounding the periphery has been used for a long time. However, since such a cable bead is low in productivity and high in cost, instead of this, a single metal wire is continuously wound around the cylindrical pedestal and arranged in a row, and this is arranged. A single bead core wound in multiple layers from the inner layer to the outer layer has come to be used.

図３は、重荷重用空気入りラジアルタイヤに使用される従来の１本巻きのビードコアの代表例であって、１本の金属線Ｓを環状のビードコアの軸心を中心にして、内層から外層へと順に螺旋状に巻き付けながら層状に束ね巻いて、断面形状が実質的に六辺からなる六角形にするのが一般的であった。しかしながら、このような六角ビードコアを使用したタイヤは、スチールカーカス層の折り返し部においてカーカスコードがビードコアの角部に強く押し付けられることにより走行中にフレッチングと称するコード破断故障を生じたり、ビードコアの内径側ではカーカス層とビードコアとの間に大きな空隙が形成されるため、そこにエアが残留して製品屑故障に繋がるという問題があった。   FIG. 3 shows a typical example of a conventional single-winding bead core used in a heavy-duty pneumatic radial tire. One metal wire S is centered on the axis of the annular bead core and is formed from the inner layer to the outer layer. In general, the cross-sectional shape is substantially a hexagonal shape consisting of six sides. However, in a tire using such a hexagonal bead core, the carcass cord is strongly pressed against the corner of the bead core at the folded portion of the steel carcass layer. However, since a large gap is formed between the carcass layer and the bead core, there is a problem in that air remains in the carcass layer and leads to a product waste failure.

このような問題の対策として、図４に例示するように、ビードコアの断面形状をタイヤ回転軸に対して垂直方向の中間側辺Ｒ２を有する八角形状にしたり、八角形状の上下辺を長辺とするなどの提案がある（特許文献１、２参照。）。しかしながら、これらの改良された多辺形ビードコアでも、ビードコアの内径側のカーカス層との間に生ずる空隙は依然として解消されておらず、そのためエアが残留することによりタイヤ故障を発生させることから、未だ改良の余地を残していた。
特開平９−２５４６１１号公報 特公昭６４−１０３６５号公報 As a countermeasure for such a problem, as illustrated in FIG. 4, the cross-sectional shape of the bead core is an octagon having an intermediate side R2 perpendicular to the tire rotation axis, or the upper and lower sides of the octagon are long sides. There is a proposal such as (see Patent Documents 1 and 2). However, even with these improved multi-sided bead cores, the air gap generated between the bead core and the carcass layer on the inner diameter side is still not eliminated, and as a result, tire failure occurs due to residual air. There was room for improvement.
JP-A-9-254611 Japanese Patent Publication No. 64-10365

本発明の目的は、かかる従来の問題点を解消するもので、カーカス層とビードコアとの密着性を高めてカーカスコードのフレッチングによる破断故障やエア溜りに起因するタイヤ故障を減少するようにした重荷重用空気入りラジアルタイヤのビードコアを提供することにある。   An object of the present invention is to eliminate such a conventional problem, and to increase the adhesion between the carcass layer and the bead core, thereby reducing the failure caused by fretting of the carcass cord and the tire failure caused by air accumulation. The object is to provide a bead core for a heavy duty pneumatic radial tire.

上記目的を達成するための本発明の重荷重用空気入りラジアルタイヤのビードコアは、１本の金属線をビードコアの軸周りに螺旋状に軸方向に配列するように巻回し、該軸方向の配列層を内層から外層へ順次巻き重ね、かつ層間で前記金属線の配列ピッチを１／２ずつずらせるようにして環状の金属線束にした重荷重用空気入りラジアルタイヤのビードコアにおいて、少なくとも前記ビードコアの内径側の断面形状を、該ビードコアの軸方向に平行な底辺と、該ビードコアの軸方向に垂直な左右両側の中間側辺と、該左右の中間側辺の各内端と前記底辺の両端とをそれぞれ繋ぐ鈍角の２辺からなる斜辺とから形成したことを特徴とする。   In order to achieve the above object, a bead core of a heavy-duty pneumatic radial tire according to the present invention is formed by winding a single metal wire so as to be spirally arranged around the axis of the bead core in the axial direction. In the bead core of a heavy-duty pneumatic radial tire in which the metal wire is sequentially wound from the inner layer to the outer layer, and the metal wire arrangement pitch is shifted by ½ between the layers to form an annular metal wire bundle, at least the inner diameter side of the bead core The cross-sectional shape of each of the bottom side parallel to the axial direction of the bead core, the middle side sides on both left and right sides perpendicular to the axial direction of the bead core, the inner ends of the left and right middle side sides, and both ends of the bottom side, respectively It is characterized by being formed from a hypotenuse consisting of two obtuse angles connecting.

本発明の重荷重用空気入りラジアルタイヤのビードコアは、ビードコアの内径側の断面形状をビードコアの軸方向に平行な底辺と、該ビードコアの軸方向に垂直な左右両側の中間側辺と、該左右の中間側辺の各内端と前記底辺の両端とをそれぞれ繋ぐ鈍角の２辺からなる斜辺とから形成したので、ビードコアの内径側で折り返されるカーカス層に対して局部的な角部が接触したり、大きな空隙を形成しないので、ビードコアとカーカス層間のフレッチングを防止すると共に、エア溜りに起因するタイヤ故障を防止することができる。   The bead core of the heavy-duty pneumatic radial tire of the present invention has a cross-sectional shape on the inner diameter side of the bead core, a bottom side parallel to the axial direction of the bead core, intermediate side sides on both left and right sides perpendicular to the axial direction of the bead core, and Since it is formed from two oblique sides having obtuse angles that connect the inner ends of the intermediate side and both ends of the bottom side, local corners are in contact with the carcass layer folded back on the inner diameter side of the bead core. Since a large gap is not formed, fretting between the bead core and the carcass layer can be prevented, and a tire failure due to air accumulation can be prevented.

特に、最内層の金属線の配列数をｎとして、第２層をｎ＋３、第３層をｎ＋６としたので、カーカス層の折り返し部におけるビードコアとの密着性が一層向上し、上記する効果を一層顕著にすることができる。   In particular, since the number of arrangement of the innermost metal lines is n, the second layer is n + 3, and the third layer is n + 6, the adhesion with the bead core at the folded portion of the carcass layer is further improved, and the above effects are further enhanced. Can be noticeable.

さらに、ビードコアの断面形状を実質的に１２辺形からなる略円形に近い形状にしたので、ビードコア環体としての曲げ剛性を高めてビードコアの捩れ変形を防止することができる。   Furthermore, since the cross-sectional shape of the bead core is substantially a substantially circular shape consisting of a dodecagon, it is possible to increase the bending rigidity of the bead core ring and prevent torsional deformation of the bead core.

以下、本発明の構成につき添付の図面を参照しながら詳細に説明する。   Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

図１及び図２は本発明の実施形態による重荷重用空気入りラジアルタイヤのビードコア（以下、単にビードコアという）の一部を示す断面図である。   1 and 2 are cross-sectional views showing a part of a bead core (hereinafter simply referred to as a bead core) of a heavy duty pneumatic radial tire according to an embodiment of the present invention.

図１において、ビードコア１は、１本の金属線Ｓをビードコア１の軸（一般にタイヤ回転軸に一致する軸）周りに螺旋状に巻き付けて形成されたもので、各層がビードコア１の軸に平行な方向Ｘに配列するように並べられている。軸方向に並ぶ金属線Ｓの配列層は内層から外層へ順次巻き重ねられ、かつ、層間で金属線Ｓの配列ピッチを１／２ずつずらせるように積層されることにより環状の金属線束Ｒとして構成されている。   In FIG. 1, a bead core 1 is formed by spirally winding a single metal wire S around an axis of the bead core 1 (generally an axis that coincides with the tire rotation axis), and each layer is parallel to the axis of the bead core 1. Are arranged in a certain direction X. The arrangement layer of the metal wires S arranged in the axial direction is sequentially wound from the inner layer to the outer layer, and is laminated so that the arrangement pitch of the metal wires S is shifted by 1/2 between the layers, thereby forming an annular metal wire bundle R. It is configured.

金属線束Ｒからなるビードコア１を構成する配列層における金属線Ｓの配列数は、最内層をｎ（図ではｎ＝４）として、第２層目をｎ＋３、第３層目をｎ＋６、としている。そして、このような配列数の組み合わせにより、金属線束Ｒの断面中心から内径側の断面を、ビードコア１の軸方向Ｘに平行な底辺Ｒ１と、軸方向Ｘに垂直な左右両側の中間側辺Ｒ２、Ｒ２と、左右両側の中間側辺Ｒ２、Ｒ２の各内端と底辺Ｒ１の両端とをそれぞれ繋ぐ２辺の接角を鈍角とする斜辺Ｒ３、Ｒ４とからなる形状に形成している。   The number of arrangement of the metal lines S in the arrangement layer constituting the bead core 1 composed of the metal wire bundle R is n + 3 for the second layer and n + 6 for the third layer, where n is the innermost layer (n = 4 in the figure). . And by such a combination of the number of arrangements, the cross section from the center of the cross section of the metal wire bundle R to the inner diameter side is divided into a base R1 parallel to the axial direction X of the bead core 1 and an intermediate side R2 on both left and right sides perpendicular to the axial direction X. , R2 and the oblique sides R3, R4 having an obtuse angle between the two sides connecting the inner ends of the intermediate sides R2, R2 on both the left and right sides and both ends of the bottom side R1, respectively.

金属線束Ｒの最内層から第４層目以上の中間側辺Ｒ２までの各配列層における金属線Ｓの配列数は、特に限定されるものではないが、好ましくは図１に例示するように、内径側の斜辺Ｒ３を形成する配列層は隣接する内層側の配列数より順次３本ずつ増加させ、外径側の斜辺Ｒ４を形成する配列層は隣接する内層側の配列数よりも順次１本ずつ増加させるとよい。さらに、中間側辺Ｒ２を形成する配列層では、各配列層毎に隣接する層間の配列数を交互に１本ずつ減少及び増加を繰り返して配列するとよい。   The number of arrangement of the metal lines S in each arrangement layer from the innermost layer of the metal wire bundle R to the intermediate side R2 of the fourth or higher layer is not particularly limited, but preferably as illustrated in FIG. The array layer forming the inner hypotenuse R3 is sequentially increased by three from the number of adjacent inner layer side arrays, and the array layer forming the outer hypotenuse R4 is sequentially one array from the adjacent inner layer side. It is good to increase it step by step. Furthermore, in the arrangement layer forming the intermediate side R2, it is preferable to arrange the arrangement number between adjacent layers for each arrangement layer by alternately decreasing and increasing one by one.

最内層（底辺Ｒ１）を構成する金属線Ｓの配列数ｎは下限を２以上とし、上限は最大幅を形成している左右両側の中間側辺Ｒ２、Ｒ２間の配列層のうちの最大配列数ｎｍａｘを底辺Ｒ１の配列数ｎの０．２５〜０．５０倍 、好ましくは０．３６〜０．４４倍にするとよい。底辺Ｒ１における金属線Ｓの配列数と最大幅における金属線Ｓの配列数との関係を上記の範囲にすることにより、底辺Ｒ１と左右両側の中間側辺Ｒ２、Ｒ２とを繋ぐ斜辺Ｒ３、Ｒ４の長さを底辺Ｒ１と略同等にするため、カーカス層のビードコア１に対する折り返しをより密接可能にする。   The arrangement number n of the metal lines S constituting the innermost layer (base R1) has a lower limit of 2 or more, and the upper limit is the maximum arrangement of the arrangement layers between the left and right intermediate sides R2 and R2 forming the maximum width. The number nmax may be 0.25 to 0.50 times, preferably 0.36 to 0.44 times the number of arrangement n of the base R1. By setting the relationship between the number of metal lines S arranged at the base R1 and the number of metal lines S arranged at the maximum width within the above range, the hypotenuses R3 and R4 connecting the base R1 and the intermediate sides R2 and R2 on the left and right sides. Therefore, the carcass layer can be folded back with respect to the bead core 1 more closely to the base R1.

このように金属線束Ｒの内径側の断面を形成することにより、ビードコア１の表面に大きな突出する角部が形成されず、ビードコアの内径側に巻き付け折り返されるカーカス層に対して局部的な接触によるフレッチングを起こしたり、また大きな空隙を形成しないので、エア溜りに起因するタイヤ故障を防止することができる。   By forming a cross section on the inner diameter side of the metal wire bundle R in this way, a large protruding corner portion is not formed on the surface of the bead core 1, but by local contact with the carcass layer wound and folded around the inner diameter side of the bead core. Since fretting does not occur and a large gap is not formed, tire failure due to air accumulation can be prevented.

本発明において、金属線束Ｒの断面中心から外径側の断面形状は、特に限定されるものではないが、好ましくは、内径側の断面形状と鏡対称にするとよい。すなわち、ビードコア１の軸に平行な方向Ｘに延長する頂辺Ｒ５と、この頂辺Ｒ５の両端と左右両側の中間側辺Ｒ２、Ｒ２の各外端とをそれぞれ繋ぐ２辺の接角を鈍角とする斜辺Ｒ６、Ｒ７とからなる形状とする。このように内径側と外径側とを鏡対称にして金属線束Ｒの断面を実質的に１２辺形に形成するとよい。   In the present invention, the cross-sectional shape on the outer diameter side from the cross-sectional center of the metal wire bundle R is not particularly limited, but is preferably mirror-symmetric with the cross-sectional shape on the inner diameter side. That is, the tangent angle between two sides connecting the apex R5 extending in the direction X parallel to the axis of the bead core 1 and both ends of the apex R5 and the outer sides of the right and left intermediate sides R2 and R2 is an obtuse angle. The shape is composed of the hypotenuses R6 and R7. As described above, the inner diameter side and the outer diameter side are mirror-symmetrical, and the cross section of the metal wire bundle R is preferably formed in a substantially dodecagonal shape.

このように金属線束Ｒの断面を形成することにより、ビードコア１の断面を略円形に近い形状にするので、カーカス層が巻き付けられたときの捩じり剛性が向上し、ビードコア１の捩じりに対する耐久性を向上させることができる。   By forming the cross-section of the metal wire bundle R in this way, the cross-section of the bead core 1 is made to be a substantially circular shape, so that the torsional rigidity when the carcass layer is wound is improved, and the torsion of the bead core 1 is improved. The durability with respect to can be improved.

図２は、本発明の他の実施形態によるビードコアの断面を示している。本実施形態が図１の実施形態と異なる点は、ビードコア１を構成する金属線束Ｒの配列層の数及び各配列層における金属線Ｓの配列数を異にしていることにある。   FIG. 2 shows a cross-section of a bead core according to another embodiment of the present invention. This embodiment is different from the embodiment of FIG. 1 in that the number of arrangement layers of the metal wire bundle R constituting the bead core 1 and the arrangement number of the metal wires S in each arrangement layer are different.

ビードコア１を構成する金属線束Ｒは、断面形状を実質的に１２辺形とし、底辺Ｒ１及び頂辺Ｒ５を形成する配列層における金属線Ｓの配列数を７とし、斜辺Ｒ３及びＲ６を形成する配列層の数を３にすると共に各配列層における金属線Ｓの配列数を隣接層より３ずつ増加又は減少させ、斜辺Ｒ４及びＲ７を形成する配列層の数を５にすると共に各配列層における金属線Ｓの配列数を隣接層より１ずつ増加又は減少させ、左右の中間側辺Ｒ２、Ｒ２を形成する配列層の数を７にすると共に各配列層における金属線Ｓの配列数を隣接層より交互に１ずつ増減させている。   The metal wire bundle R constituting the bead core 1 has a substantially cross-sectional shape of 12 sides, the number of arrangements of the metal lines S in the arrangement layer forming the bottom side R1 and the top side R5 is 7, and the oblique sides R3 and R6 are formed. The number of arrangement layers is set to 3, and the arrangement number of the metal lines S in each arrangement layer is increased or decreased by 3 from the adjacent layer, the number of arrangement layers forming the hypotenuses R4 and R7 is set to 5, and The number of arrangement of the metal lines S is increased or decreased by 1 from the adjacent layer, the number of arrangement layers forming the left and right intermediate sides R2 and R2 is set to 7, and the number of arrangement of the metal lines S in each arrangement layer is set to the adjacent layer. It is increased or decreased alternately one by one.

これにより、ビードコア１の断面を略円形に近い形状にして、ビードコア１の周囲に折り返されるカーカス層との間をほぼ面接触に近い状態に保つことができると共に、ビードコア環体としての曲げ剛性を高めることができるので、カーカスコードのフレッチングを防ぐと共にビードコアの捩れ変形を防止してビード部の耐久性を向上させることができる。   As a result, the cross-section of the bead core 1 can be made to be a substantially circular shape so that the bead core 1 can be kept in a state close to surface contact with the carcass layer that is folded around the bead core 1, and the bending rigidity as the bead core ring body can be maintained. Therefore, the durability of the bead portion can be improved by preventing fretting of the carcass cord and preventing torsional deformation of the bead core.

本発明のビードコア１は、破断強度を共通にする従来のビードコアに比して、ビードコアの断面幅Ｗを狭く抑えることができるので、タイヤにおけるビード部の形状をコンパクトにすることができる。これにより、リムとの嵌合性を有利にすることができると共に、タイヤの軽量化にとっても有利になる。   Since the bead core 1 of the present invention can suppress the cross-sectional width W of the bead core narrower than the conventional bead core having the same breaking strength, the shape of the bead portion in the tire can be made compact. Thereby, the fitting property with the rim can be made advantageous, and it is also advantageous for reducing the weight of the tire.

直径２．０ｍｍの金属線の周囲に厚さ０．１２５ｍｍのインシュレーションゴムを被覆し、内層から外層へと各層間で金属線の配列ピッチを１／２ずつずらせながら連続して層状に束ね巻いて、表１に示すように断面形状の異なる従来のビードコア（従来例１、２）及び第１発明のビードコア（実施例）を作製した。   A metal wire having a diameter of 2.0 mm is covered with an insulation rubber having a thickness of 0.125 mm, and the inner and outer layers are continuously bundled in layers while shifting the arrangement pitch of the metal wires by 1/2 each layer. As shown in Table 1, conventional bead cores (conventional examples 1 and 2) having different cross-sectional shapes and bead cores of the first invention (examples) were produced.

上記３種のビードコアを使用して、ビードコア以外の仕様を共通にするダンプトラック用ラジアルタイヤ（サイズ：２４００Ｒ３５）を製造し、充填内圧７００ｋＰａ、負荷荷重２１８ｋＮ、速度８ｋｍ／ｈの条件の下で、室内の回転ドラム試験機で８００時間走行させた後、各タイヤを解体してビードコアと接触する位置のカーカス層を取り出した。取り出したカーカス層の折り返し部におけるエアの残留状況をチェックしてその状況を表１に記載すると共に、カーカスコード素線の断面における摩滅の程度を観察して以下の尺度により評価し、その結果をフレッチング性として表１に併記した。   Using the above three types of bead cores, a dump truck radial tire (size: 2400R35) having the same specifications other than the bead cores is manufactured, and under conditions of a filling internal pressure of 700 kPa, a load load of 218 kN, and a speed of 8 km / h, After running for 800 hours with an indoor rotating drum tester, each tire was disassembled and the carcass layer at a position in contact with the bead core was taken out. The remaining state of air in the folded part of the carcass layer taken out was checked and described in Table 1. The degree of abrasion in the cross section of the carcass cord strand was observed and evaluated according to the following scale. The fretting properties are also shown in Table 1.

〔フレッチング性評価尺度〕
０点：カーカスコード素線に摩滅なし。
１点：カーカスコード素線断面に２０％以下の摩滅あり。
２点：カーカスコード素線断面に２０％超５０％以下の摩滅あり。
３点：カーカスコード素線断面に５０％超８０％以下の摩滅あり。
４点：カーカスコード素線の破断あり。 [Fretting evaluation scale]
0 point: No wear on the carcass cord.
1 point: 20% or less wear on the cross section of the carcass cord.
2 points: Wear of more than 20% and less than 50% in the cross section of the carcass cord.
3 points: Wear of 50% or more and 80% or less on the cross section of the carcass cord.
4 points: Carcass cord strand was broken.

Figure 2005088793
表１の結果から、実施例のビードコアは、タイヤのカーカス層の折り返し部にエアーを残留させず、従来例１、２に比較してカーカスコードの耐フレッチング性を向上させていることがわかる。
Figure 2005088793
 From the results of Table 1, it can be seen that the bead core of the example does not leave air in the folded portion of the carcass layer of the tire and improves the fretting resistance of the carcass cord as compared with the conventional examples 1 and 2.

本発明の実施形態からなる重荷重用空気入りラジアルタイヤのビードコアの一例を示す断面図である。It is sectional drawing which shows an example of the bead core of the heavy-duty pneumatic radial tire which consists of embodiment of this invention. 本発明の他の実施形態からなる重荷重用空気入りラジアルタイヤのビードコアの一例を示す断面図である。It is sectional drawing which shows an example of the bead core of the heavy-duty pneumatic radial tire which consists of other embodiment of this invention. 従来の６角ビードを示す断面図である。It is sectional drawing which shows the conventional hexagon bead. 従来の８角ビードを示す断面図である。It is sectional drawing which shows the conventional octagon bead.

符号の説明Explanation of symbols

１ ビードコア
Ｓ 金属線
Ｒ 金属線束
Ｒ１ 底辺
Ｒ２ 中間側辺
Ｒ３、Ｒ４、Ｒ６、Ｒ７ 斜辺
Ｒ５ 頂辺
1 Bead core S Metal wire R Metal wire bundle R1 Bottom R2 Middle side R3, R4, R6, R7 Oblique side R5 Top side

Claims (5)

１本の金属線をビードコアの軸周りに螺旋状に軸方向に配列するように巻回し、該軸方向の配列層を内層から外層へ順次巻き重ね、かつ層間で前記金属線の配列ピッチを１／２ずつずらせるようにして環状の金属線束にした重荷重用空気入りラジアルタイヤのビードコアにおいて、
少なくとも前記ビードコアの断面中心から内径側の断面形状を、該ビードコアの軸方向に平行な底辺と、該ビードコアの軸方向に垂直な左右両側の中間側辺と、該左右の中間側辺の各内端と前記底辺の両端とをそれぞれ繋ぐ鈍角の２辺からなる斜辺とから形成した重荷重用空気入りラジアルタイヤのビードコア。 One metal wire is wound around the bead core so as to be spirally arranged in the axial direction, the axially arranged layers are sequentially wound from the inner layer to the outer layer, and the arrangement pitch of the metal wires is set to 1 between the layers. / In the bead core of a heavy-duty pneumatic radial tire that is made to be shifted by 2 to form an annular metal wire bundle,
At least the cross-sectional shape on the inner diameter side from the center of the cross-section of the bead core, the bottom side parallel to the axial direction of the bead core, the middle side sides on both the right and left sides perpendicular to the axial direction of the bead core, and the inner sides of the left and right middle side sides A bead core for a heavy-duty pneumatic radial tire formed of a hypotenuse consisting of two obtuse angles connecting the end and both ends of the base. 前記ビードコアの断面中心から外径側の断面形状を、該ビードコアの軸方向に平行な頂辺と、前記左右の中間側辺の各外端と前記頂辺の両端とをそれぞれ繋ぐ鈍角の２辺からなる斜辺とから形成し、前記ビードコアの断面形状を実質的に１２辺形にした請求項１に記載の重荷重用空気入りラジアルタイヤのビードコア。   An obtuse angle of two cross-sectional shapes on the outer diameter side from the center of the cross-section of the bead core, each connecting the top side parallel to the axial direction of the bead core and each outer end of the left and right intermediate sides and both ends of the top side. The bead core of a heavy-duty pneumatic radial tire according to claim 1, wherein the bead core has a substantially dodecagonal cross-sectional shape. 前記金属線束の配列数を最内層をｎとして少なくとも第２層をｎ＋３、第３層をｎ＋６にした請求項１又は２に記載の重荷重用空気入りラジアルタイヤのビードコア。   The bead core of a heavy-duty pneumatic radial tire according to claim 1 or 2, wherein the number of arrangements of the metal wire bundles is such that the innermost layer is n, the second layer is n + 3, and the third layer is n + 6. 前記金属線束の最内層における金属線の配列数ｎと最大幅における金属線の配列数ｎｍａｘとの比ｎ／ｎｍａｘを０．２５〜０．５０にした請求項１、２又は３に記載の重荷重用空気入りラジアルタイヤのビードコア。   The heavy load according to claim 1, 2, or 3, wherein a ratio n / nmax between an arrangement number n of metal lines in the innermost layer of the metal wire bundle and an arrangement number nmax of metal lines in the maximum width is 0.25 to 0.50. Heavy-duty pneumatic radial tire bead core. 請求項１〜４の何れか１項に記載のビードコアを埋設した重荷重用空気入りラジアルタイヤ。
A heavy-duty pneumatic radial tire in which the bead core according to any one of claims 1 to 4 is embedded.
JP2003326458A 2003-09-18 2003-09-18 Bead core of heavy load, pneumatic radial-ply tire Pending JP2005088793A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007055465A (en) * 2005-08-25 2007-03-08 Bridgestone Corp Bead core and pneumatic tire using it
CN102441626A (en) * 2011-11-07 2012-05-09 三角轮胎股份有限公司 Nearly circular bead ring
CN107953726A (en) * 2017-12-07 2018-04-24 合肥万力轮胎有限公司 A kind of tire wire loop structure, winding disc and winding method
WO2024036477A1 (en) * 2022-08-16 2024-02-22 横滨橡胶株式会社 Pneumatic tire

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007055465A (en) * 2005-08-25 2007-03-08 Bridgestone Corp Bead core and pneumatic tire using it
CN102441626A (en) * 2011-11-07 2012-05-09 三角轮胎股份有限公司 Nearly circular bead ring
CN107953726A (en) * 2017-12-07 2018-04-24 合肥万力轮胎有限公司 A kind of tire wire loop structure, winding disc and winding method
WO2024036477A1 (en) * 2022-08-16 2024-02-22 横滨橡胶株式会社 Pneumatic tire

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