JP3606475B2 - Steel cord for reinforcing rubber articles and pneumatic radial tire - Google Patents
Steel cord for reinforcing rubber articles and pneumatic radial tire Download PDFInfo
- Publication number
- JP3606475B2 JP3606475B2 JP01884095A JP1884095A JP3606475B2 JP 3606475 B2 JP3606475 B2 JP 3606475B2 JP 01884095 A JP01884095 A JP 01884095A JP 1884095 A JP1884095 A JP 1884095A JP 3606475 B2 JP3606475 B2 JP 3606475B2
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- Prior art keywords
- filament
- core
- cord
- filaments
- steel
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- 229910000831 Steel Inorganic materials 0.000 title claims description 29
- 239000010959 steel Substances 0.000 title claims description 29
- 230000003014 reinforcing effect Effects 0.000 title claims description 10
- 238000000465 moulding Methods 0.000 description 3
- 239000012779 reinforcing material Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
Images
Classifications
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
- D07B1/0646—Reinforcing cords for rubber or plastic articles comprising longitudinally preformed wires
- D07B1/0653—Reinforcing cords for rubber or plastic articles comprising longitudinally preformed wires in the core
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
- D07B1/062—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration
- D07B1/0626—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration the reinforcing cords consisting of three core wires or filaments and at least one layer of outer wires or filaments, i.e. a 3+N configuration
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2015—Strands
- D07B2201/2024—Strands twisted
- D07B2201/2029—Open winding
- D07B2201/2031—Different twist pitch
- D07B2201/2032—Different twist pitch compared with the core
Landscapes
- Tyre Moulding (AREA)
- Ropes Or Cables (AREA)
- Tires In General (AREA)
Description
【0001】
【産業上の利用分野】
本発明はゴム物品補強用スチールコードに関し、詳しくは破断寿命が改善されたゴム物品補強用スチールコードおよび該コードをカーカスプライコードとして用いた空気入りラジアルタイヤに関するものである。
【0002】
【従来の技術】
従来、トラック、バス用の大型タイヤに用いられるスチールコードにおいては、3本のコアフィラメントと9本のシースフィラメントと1本のラップフィラメントとからなる3+9+1構造のものがよく知られている。
【0003】
【発明が解決しようとする課題】
かかる3+9+1構造のスチールコードにおいて、12本のフィラメントの外側に巻きつけらた1本のラップフィラメントを除去し、さらに9本のシースフィラメントの本数を減らして7〜8本としたスチールコードは、タイヤ走行中におけるラップフィラメントとシースフィラメントとのフレッティング摩耗がなくなり、またシースフィラメントの本数を減じたことによりコード内部にゴムが浸入し易くなり各フィラメント間の接触が緩和されることにより、コード強力の低下を防ぐことができる。
【0004】
しかし、このような3+7構造や3+8構造のスチールコードを補強材として使用した空気入りタイヤを実際に走行させたところ、その走行寿命に大きなばらつきがでるという問題を生じた。
【0005】
そこで本発明の目的は、かかる走行寿命のばらつきの原因を究明し、3+7構造や3+8構造のスチールコードにおいて、その破断寿命を改善し、空気入りタイヤの走行寿命をばらつきなく安定して延ばすことにある。
【0006】
【課題を解決するための手段】
本発明者は、上記課題を解決するために走行中のタイヤの補強コードの挙動について鋭意研究を行ったところ、下記の如き知見を得るに至った。
【0007】
走行中には、タイヤの補強スチールコードに対して引張り、曲げ等の入力がかかり、その際、コード内のフィラメント同士の接触部に繰り返しの接触圧が生じる。かかる接触圧の生じた部分において、スチールフィラメントの材質疲労が起こり、破断の核となる。ここで、3+7や3+8構造の如き、ラップフィラメントがなくかつシース間に隙間を設けゴムがコード内部に浸入し易くした構造においては、スチールフィラメント同士が直接接触しているコア−コア間の接触部に最も大きな接触圧が生じ、そこが破断の核となる傾向が高いことが分かった。すなわち、通常、スチールコードを構成するフィラメントは波形に屈曲型付けされた後に撚り合わされているが、この型付け率が小さいと撚りの戻ろうとする力が大きくなり、接触しているコア−コア間のフィラメントの接触圧が大きくなり、材質疲労の進行が増大することが分かった。
【0008】
そこで、本発明者は、かかる知見に基づきさらに鋭意研究を行った結果、コアフィラメントに型付けを施し、その型付け率を所定の範囲に限定したところ、上記コア−コア間の接触部の接触圧が低下し得ることを見出し、本発明を完成するに至った。
【0009】
すなわち、本発明は、3本のスチールフィラメントを撚り合わせたコアと、その周りに7〜8本のスチールフィラメントをコアと異なるピッチで撚り合わせたシースとの2層構造からなり、この2層構造の周りにラップフィラメントを巻いていないゴム物品補強用スチールコードにおいて、上記コアを構成する全てのフィラメントが波形に型付けされており、次式、
F=H/D
(式中、Hはコアフィラメントの振幅、Dはシースフィラメントを除いたコードの理想直径を表す)で表されるフィラメント型付け率Fが0.95以上であり、かつ各フィラメントの素線径が0.20〜0.24mmであることを特徴とするゴム物品補強用スチールコードに関するものである。
【0010】
また、本発明は、上記ゴム物品補強用スチールコードをプライコードとして使用した空気入りラジアルタイヤに関するものである。
【0011】
ここで、シースフィラメントを除いたコードの理想直径Dとは、3本のコアフィラメントが互いに隙間なく撚り合わされていると仮定した場合の、コード断面におけるコアフィラメント層の外接円の直径をいう(図1(イ))。また、コアフィラメントの振幅Hとは、フィラメントを波形に屈曲型付けして撚り合せるときの、波形の振幅の大きさである(図1(ロ))。
【0012】
【作用】
本発明のスチールコードは、上記式で規定されるコアフィラメントの型付け率Fが0.95以上であり、これは、この値が0.95未満のスチールコードに比べコードの破断寿命が格段に良好となる。よって、かかるスチールコードを補強材として用いた空気入りタイヤは、走行寿命のばらつきが減少し、長寿命化が達成される。
【0013】
本発明においては、ラップフィラメントを除去したことにより各フィラメント同士の接触圧が低減し、フィラメント同士の接触部分から生じる腐食クラックの進展が抑制される。
【0014】
また、コア−シース間へのゴム浸入を良好に確保するためにコアフィラメントのピッチとシースフィラメントのピッチとを異ならしめる。好ましくはコアピッチ:シースピッチを1:2程度とする。
【0015】
本発明においては、すべてのフィラメントはほぼ同一線径であることが好ましい。コード内で多数種のフィラメント径を組み合わせて用いると製造コストが上がるからである。
【0016】
また、コアとシースの撚り方向は同一方向であることが好ましい。異方向ではコアとシースの接触部分での接触角が大きくなり、コアとシース間の接触圧が増加し、コードの耐疲労性が低下するからである。
【0017】
なお、シースフィラメントの本数が6本以下であると、必要なコード強力を維持するためにはフィラメント径を太くしなければならず、破断寿命に問題を生じ、一方、9本の場合は、前述の如くコード内部へゴムが浸入しにくくなり、耐腐食性に問題を生ずる。
【0018】
さらに本発明においては、各フィラメントの素線径を0.20〜0.24mmとすることが好ましい。この素線径が0.20mmよりも細いと、タイヤのプライコードとして使用した場合にタイヤサイド部の単位面積当りの強度、すなわち安全率を十分に保つことができず、耐サイドカット性に劣り、一方0.24mmよりも太いと破断寿命の改善が困難となる。より好ましくは、各フィラメントの素線径を0.21〜0.23mmとする。
【0019】
【実施例】
次に本発明を実施例および比較例により具体的に説明する。
下記の表1および表2に従うスチールコードを試作した。
試作した各種スチールコードを打込み数30本/5cmにてカーカスプライに適用して、サイズ10.00R20のトラック、バス用ラジアルタイヤを作製し、10万kmの実地走行後のタイヤのコアフィラメントの破断寿命を下記式より求め、実施例1を100とした指数で表した。数値の小さいほどコアフィラメントの耐疲労性に優れていることを示す。
【0020】
コアフィラメント破断率={(タイヤより取り出したコード中の破断したコアフィラメントの総本数/タイヤより取り出したコード中のコアフィラメントの総本数)}×100
得られた結果を下記の表1および表2に併記する。
【0021】
【表1】
【0022】
【表2】
【0023】
上記表1および表2から明らかなように、本発明のスチールコードは、比較例に比べて大幅にコアフィラメントの破断寿命が延びていることが分かる。
【0024】
【発明の効果】
以上説明してきたように本発明のスチールコードにおいては、ラップフィラメントを除去したことでシースフィラメントとラップフィラメントとのフレッティング摩耗がなくなり、かつコアフィラメントに型付けを施しその型付け率を所定の範囲に限定したことにより、その破断寿命が大幅に改善されるという効果が得られる。よって、かかるスチールコードを補強材として用いた空気入りタイヤの走行寿命は、ばらつきなく安定してかつ大幅に向上する。
【図面の簡単な説明】
【図1】(ア)は、コードの理想直径Dを表す説明図である。
(イ)は、コアフィラメントの振幅Hを表す説明図である。[0001]
[Industrial application fields]
The present invention relates to a steel cord for reinforcing rubber articles, and more particularly, to a steel cord for reinforcing rubber articles having an improved fracture life and a pneumatic radial tire using the cord as a carcass ply cord.
[0002]
[Prior art]
Conventionally, steel cords used for large tires for trucks and buses are well known to have a 3 + 9 + 1 structure composed of three core filaments, nine sheath filaments, and one wrap filament.
[0003]
[Problems to be solved by the invention]
In such a steel cord having a 3 + 9 + 1 structure, one wrap filament wound around the outer side of 12 filaments is removed, and the number of 9 sheath filaments is further reduced to 7 to 8 steel cords. The fretting wear between the wrap filament and the sheath filament during running is eliminated, and the number of sheath filaments is reduced, so that rubber can easily enter the inside of the cord and the contact between each filament is eased. Decline can be prevented.
[0004]
However, when a pneumatic tire using a steel cord having such a 3 + 7 structure or a 3 + 8 structure as a reinforcing material was actually run, there was a problem that the running life varied greatly.
[0005]
Accordingly, an object of the present invention is to investigate the cause of such variations in running life, to improve the breaking life of steel cords having a 3 + 7 structure or a 3 + 8 structure, and to stably extend the running life of a pneumatic tire without variation. is there.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor has conducted earnest research on the behavior of the reinforcing cord of a running tire, and has obtained the following knowledge.
[0007]
During running, an input such as pulling or bending is applied to the reinforcing steel cord of the tire, and at that time, repeated contact pressure is generated at the contact portion between the filaments in the cord. In the portion where the contact pressure is generated, material fatigue of the steel filament occurs, which becomes the core of fracture. Here, in a structure such as a 3 + 7 or 3 + 8 structure in which there is no wrap filament and a gap is provided between the sheaths so that rubber can easily enter the inside of the cord, the contact portion between the cores where the steel filaments are in direct contact It was found that the largest contact pressure was generated in the film, and that the tendency to become the core of fracture was high. In other words, the filaments that make up the steel cord are usually twisted after being bent into a corrugated shape, but if this molding rate is small, the force to return the twist increases, and the filament between the core and the core in contact with each other It has been found that the contact pressure increases and the progress of material fatigue increases.
[0008]
Therefore, as a result of further diligent research based on such knowledge, the present inventor performed mold forming on the core filament, and when the mold forming rate was limited to a predetermined range, the contact pressure at the contact portion between the core and core was It has been found that it can be lowered, and the present invention has been completed.
[0009]
That is, the present invention comprises a two-layer structure of a core in which three steel filaments are twisted together and a sheath in which 7 to 8 steel filaments are twisted at a different pitch from the core. In the steel cord for reinforcing rubber articles in which no wrap filament is wound around, all the filaments constituting the core are molded into a corrugated shape,
F = H / D
(Where H represents the amplitude of the core filament, D represents the ideal diameter of the cord excluding the sheath filament), and the filament forming rate F is 0.95 or more, and the filament diameter of each filament is 0. The present invention relates to a steel cord for reinforcing rubber articles characterized by being 20 to 0.24 mm.
[0010]
The present invention also relates to a pneumatic radial tire using the steel cord for reinforcing rubber articles as a ply cord.
[0011]
Here, the ideal diameter D of the cord excluding the sheath filament refers to the diameter of the circumscribed circle of the core filament layer in the cord cross section when it is assumed that the three core filaments are twisted together without any gap (see FIG. 1 (I)). The amplitude H of the core filament is the amplitude of the waveform when the filament is bent and twisted into a waveform (FIG. 1 (b)).
[0012]
[Action]
The steel cord of the present invention has a core filament molding rate F defined by the above formula of 0.95 or more, which is significantly better than the steel cord having a value less than 0.95. It becomes. Therefore, in the pneumatic tire using such a steel cord as a reinforcing material, variation in running life is reduced, and a longer life is achieved.
[0013]
In the present invention, by removing the wrap filaments, the contact pressure between the filaments is reduced, and the development of corrosion cracks generated from the contact portions between the filaments is suppressed.
[0014]
Further, in order to ensure good rubber penetration between the core and the sheath, the pitch of the core filament is made different from the pitch of the sheath filament. Preferably, the core pitch: sheath pitch is about 1: 2.
[0015]
In the present invention, it is preferable that all filaments have substantially the same wire diameter. This is because the manufacturing cost increases when a plurality of types of filament diameters are used in combination in the cord.
[0016]
Moreover, it is preferable that the twist direction of a core and a sheath is the same direction. This is because in a different direction, the contact angle at the contact portion between the core and the sheath increases, the contact pressure between the core and the sheath increases, and the fatigue resistance of the cord decreases.
[0017]
If the number of sheath filaments is 6 or less, the filament diameter must be increased in order to maintain the necessary cord strength, which causes a problem in the breaking life. As described above, it is difficult for rubber to enter the inside of the cord, which causes a problem in corrosion resistance.
[0018]
Furthermore, in the present invention, the filament diameter of each filament is preferably 0.20 to 0.24 mm. If this wire diameter is thinner than 0.20 mm, the strength per unit area of the tire side part, that is, the safety factor cannot be sufficiently maintained when used as a ply cord of a tire, and the side cut resistance is inferior. On the other hand, if the thickness is larger than 0.24 mm, it is difficult to improve the fracture life. More preferably, the filament diameter of each filament is 0.21 to 0.23 mm.
[0019]
【Example】
Next, the present invention will be specifically described with reference to examples and comparative examples.
Steel cords according to the following Table 1 and Table 2 were made as trial products.
Trial steel cords were applied to the carcass ply at a driving number of 30 / 5cm to produce radial tires for trucks and buses of size 10.00R20, and the core filaments of the tires after the actual running of 100,000 km were broken. The lifetime was obtained from the following formula and expressed as an index with Example 1 as 100. The smaller the value, the better the fatigue resistance of the core filament.
[0020]
Core filament breaking rate = {(total number of core filaments broken in cord taken out of tire / total number of core filaments in cord taken out of tire)} × 100
The obtained results are shown in Table 1 and Table 2 below.
[0021]
[Table 1]
[0022]
[Table 2]
[0023]
As is apparent from Tables 1 and 2 above, it can be seen that the steel cord of the present invention has a significantly longer core filament fracture life than the comparative example.
[0024]
【The invention's effect】
As described above, in the steel cord of the present invention, by removing the wrap filament, the fretting wear between the sheath filament and the wrap filament is eliminated, and the core filament is molded and its molding rate is limited to a predetermined range. By doing so, the effect that the fracture life is significantly improved can be obtained. Therefore, the running life of a pneumatic tire using such a steel cord as a reinforcing material is stable and greatly improved without variation.
[Brief description of the drawings]
FIG. 1A is an explanatory diagram showing an ideal diameter D of a cord.
(A) is explanatory drawing showing the amplitude H of a core filament.
Claims (2)
上記コアを構成する全てのフィラメントが波形に型付けされており、次式、
F=H/D
(式中、Hはコアフィラメントの振幅、Dはシースフィラメントを除いたコードの理想直径を表す)で表されるフィラメント型付け率Fが0.95以上であり、かつ各フィラメントの素線径が0.20〜0.24mmであることを特徴とするゴム物品補強用スチールコード。It consists of a two-layer structure consisting of a core in which three steel filaments are twisted and a sheath in which seven to eight steel filaments are twisted around the core at a different pitch from the core. In steel cords for reinforcing rubber articles that are not wound,
All the filaments that make up the core are molded into a waveform,
F = H / D
(Where H represents the amplitude of the core filament, D represents the ideal diameter of the cord excluding the sheath filament), and the filament forming rate F is 0.95 or more, and the filament diameter of each filament is 0. Steel cord for reinforcing rubber articles, characterized by being 20 to 0.24 mm .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP01884095A JP3606475B2 (en) | 1995-01-12 | 1995-01-12 | Steel cord for reinforcing rubber articles and pneumatic radial tire |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP01884095A JP3606475B2 (en) | 1995-01-12 | 1995-01-12 | Steel cord for reinforcing rubber articles and pneumatic radial tire |
Publications (2)
Publication Number | Publication Date |
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JPH08199487A JPH08199487A (en) | 1996-08-06 |
JP3606475B2 true JP3606475B2 (en) | 2005-01-05 |
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JP01884095A Expired - Fee Related JP3606475B2 (en) | 1995-01-12 | 1995-01-12 | Steel cord for reinforcing rubber articles and pneumatic radial tire |
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JP (1) | JP3606475B2 (en) |
Families Citing this family (1)
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KR20030018447A (en) * | 2001-08-28 | 2003-03-06 | 금호산업 주식회사 | Structure of the steel code in heavy duty tire |
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