EP0568271A1 - Stahlseile zur Verstärkung elastomerer Erzeugnisse und radialer Luftreifen - Google Patents

Stahlseile zur Verstärkung elastomerer Erzeugnisse und radialer Luftreifen Download PDF

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Publication number
EP0568271A1
EP0568271A1 EP93303148A EP93303148A EP0568271A1 EP 0568271 A1 EP0568271 A1 EP 0568271A1 EP 93303148 A EP93303148 A EP 93303148A EP 93303148 A EP93303148 A EP 93303148A EP 0568271 A1 EP0568271 A1 EP 0568271A1
Authority
EP
European Patent Office
Prior art keywords
steel
cord
sheath layer
filament
wrap
Prior art date
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.)
Granted
Application number
EP93303148A
Other languages
English (en)
French (fr)
Other versions
EP0568271B1 (de
Inventor
Yoshinori Kuriya
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bridgestone Corp
Original Assignee
Bridgestone Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Bridgestone Corp filed Critical Bridgestone Corp
Publication of EP0568271A1 publication Critical patent/EP0568271A1/de
Application granted granted Critical
Publication of EP0568271B1 publication Critical patent/EP0568271B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • D07B1/062—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration
    • 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
    • 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
    • D07B1/0633—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration having a multiple-layer 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
    • D07B2201/2023—Strands with core
    • 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
    • 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
    • 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
    • D07B2201/2095—Auxiliary components, e.g. electric conductors or light guides
    • D07B2201/2097—Binding wires
    • D07B2201/2098—Binding wires characterized by special properties or the arrangements of the binding wire

Definitions

  • This invention relates to steel cords used as a reinforcement for rubber articles such as pneumatic tires, industrial belts and the like as well as a pneumatic radial tire comprising a carcass ply comprised of such steel cords and having improved durability.
  • tires are well-known.
  • tires for truck and bus or for light truck generally comprise a carcass ply using cords of two or three layer construction.
  • the tensile load of the steel cord lowers during the running of the tire because the sectional area of steel filaments constituting the steel cord is decreased by fretting.
  • the decrease of sectional area in some filaments constituting the steel cord becomes conspicuous, such filaments are apt to cause breakage against tensile shock or repetitive bending.
  • tensile stress in the other filaments increases to promote fatigue breakage of the cord. Therefore, in order to increase the durability of the cord, it is required to avoid that a part of steel filaments constituting the steel cord are precedingly and prematurely broken as compared with the remaining steel filaments, and it is desirable that the tensile loads of all filaments in the cord are equally lowered.
  • an object of the invention to improve the durability of the steel cord by equally lowering the tensile loads of the steel filaments in the steel cord due to the decrease of filament sectional area through fretting during the running when the steel cords are applied to the rubber article, particularly the carcass ply of the radial tire for truck and bus.
  • the inventors have made studies with respect to steel cords formed by spirally winding a wrap steel filament around the steel cord of layer twisting structure for stably preventing the lowering of tensile load in the steel filaments (filament diameter: 0.15-0.25 mm) constituting the steel cord used in the carcass ply during the running of the tire, and found that the lowering of tensile load in the steel filaments constituting the outermost layer of the steel cord is extremely large and a main factor on the lowering of tensile load is a fretting phenomenon with the wrap filament.
  • the inventors have made studies with respect to steel cords formed by removing the wrap filament, which is the main factor on the lowering of tensile load, for preventing the occurrence of fretting around the wrap filament, and confirmed that the fretting is certainly removed to control the lowering of tensile load of the steel filament, but the restraining property of the cord is poor due to the absence of the wrap filament and when the cord is excessively bent, the steel filaments constituting the cord are scattered and finally broken when abnormal force is applied to the steel filament. In the latter case, the life at break of the cord is largely decreased as compared with the cord stabilized by wrapping the cord with the wrap filament. As a result, in order to prevent the decrease of the cord life based on the application of extreme bending force, it becomes required to restrain the cord with the steel filament in any form.
  • the inventors have made further studies with respect to the steel cord of layer twisting structure and discovered that it is advantageous to prevent the lowering of tensile load in the steel filaments of the outermost layer by controlling the application of abnormal force to the steel filament while maintaining the restraint of the filaments constituting the cord when a large bending force is applied to the cord and mitigating the fretting between the wrap filament and the steel filament constituting the outermost layer of the cord and as a result, the invention has been accomplished.
  • a steel cord for the reinforcement of rubber articles formed by twisting 1 to 4 steel filaments as a core and at least one sheath layer comprised of plural steel filaments arranged around the core, provided that a twisting pitch of at least one sheath layer is different from that of a remaining sheath layer adjacent thereto or that of the core, in which a wrap steel filament is spirally wound around a sheath layer located at an outermost side of the steel cord in the same twisting direction as in this sheath layer.
  • a pneumatic radial tire comprising a carcass ply of a radial structure toroidally extending between a pair of bead portions and containing steel cords therein, said steel cord being formed by twisting 1 to 4 steel filaments as a core and at least one sheath layer comprised of plural steel filaments arranged around the core, provided that a twisting pitch of at least one sheath layer is different from that of a remaining sheath layer adjacent thereto or that of the core, in which a wrap steel filament is spirally wound around a sheath layer located at an outermost side of the steel cord in the same twisting direction as in this sheath layer.
  • the wrap steel filament is wound around the outermost sheath layer at a twisting pitch of 2-6 mm.
  • the resistance to corrosion fatigue is improved and also the lowering of tensile load of the cord due to the fretting between the outermost sheath layer and the wrap steel filament can be controlled while maintaining the restraint of the steel filaments in the cord.
  • Figs. 1 and 2 are sectionally shown embodiments of the steel cord for the reinforcement of rubber article according to the invention having layer twisting structures of 3+9+1 and 1+6+12+1, respectively.
  • numeral 1 is a core comprised of one or three steel filaments
  • numeral 2 is a sheath layer comprised of plural steel filaments arranged adjacent to each other around the core 1.
  • the sheath layer 2 is comprised of nine steel filaments in Fig. 1 and six steel filaments in Fig. 2.
  • a second sheath layer 3 comprised of twelve steel filaments is arranged around the sheath layer 2 in the embodiment of Fig. 2.
  • numeral 4 is a wrap steel filament spirally wound around the outermost sheath layer in the same twisting direction as in the outermost sheath layer.
  • Fig. 3 is sectionally shown a third embodiment of the steel cord according to the invention having a layer twisting structure of 3+9+15+1, in which the second sheath layer 3 comprised of 15 steel filaments is arranged around the first sheath layer 2 comprised of 9 steel filaments.
  • the steel cord having a layer twisting structure of 3+8+13+1.
  • the ununiform lowering of tensile load in the steel filaments, particularly extremely lowering of tensile load in the steel filaments of the outermost sheath layer is due to the fact that the wrap steel filament is twisted in the direction opposite to the twisting direction of the steel filament in the outermost sheath layer. Since the twisting direction of the wrap steel filament is different from that of the steel filament in the outermost sheath layer, the contact area therebetween becomes small and the contact pressure per unit area is large.
  • torsion is applied to the carcass ply cord at a ground contact portion of the tire in the axial direction of the cord.
  • torsional force is applied in a direction opposite to the twisting direction of the steel filament in the outermost sheath layer
  • torsional force is created in a direction of tightening the twisting direction of the wrap steel filament and hence a relative movement between the wrap steel filament and the steel filament in the outermost sheath layer occurs.
  • the twisting direction of the spiral wrap steel filament restraining the steel cord of layer twisting structure is made in the same direction as in the steel filament of the outermost sheath layer, whereby the contact area between the steel filament in the outermost sheath layer and the wrap steel filament is increased and the contact pressure therebetween is decreased. Further, even if torsional force is applied to the cord, the relative movement between the steel filament in the outermost sheath layer and the wrap steel filament reduces and hence the reduction of sectional area in the steel filament of the outermost sheath layer and the lowering of tensile load accompanied therewith are controlled.
  • the steel filaments are restrained by the wrap steel filament, even when the cord is extremely bent, the steel filaments constituting the cord are not scattered and hence the breaking life of the cord is not lowered even when abnormal force is applied to a part of the steel filaments.
  • the filament diameter may be same or different between the core and the sheath.
  • the twisting pitch of the steel filament in the outermost sheath layer is the same as that of the spiral wrap steel filament, there is caused the falling down of the wrap steel filament into the outermost sheath layer, so that it is necessary that the twisting pitch of the steel filament in the outermost sheath layer is different from that of the wrap steel filament.
  • the invention is particularly preferable to apply the invention to a steel cord having a layer twisting structure of 3+8+1 in view of the cord durability. That is, when the invention is applied to rubber penetration type cords having a gap between the steel filaments in the sheath layer, if a large bending force is applied to the cord under a low internal pressure, the movement of the steel filaments becomes small because rubber penetrates into the inside of the cord and hence the resistance to cord breaking-up is improved.
  • Steel cords are prepared as shown in Table 1 and applied to a carcass ply of a radial tire for truck and bus having a tire size of 11/70R22.5 14PR at an end count of 22.0 cords/5 cm.
  • the fretting depth and cord breakage under large bending force are measured by running such a tire on a drum under the following test conditions:
  • steel cord of Comparative Example 1 having a layer twisting structure of 3+9+1 and a wrap steel filament of Z-lay (control)
  • steel cord of Comparative Example 2 having a layer twisting structure of 3+9 and no wrap steel filament
  • steel cord of Example 1 having a layer twisting structure of 3+9+1 and a wrap steel filament of S-lay according to the invention.
  • the measured results are shown in Table 1.
  • the steel filaments of the outermost sheath layer corresponding to two cords are taken out from the tire after the running under usual conditions and broken through a tensile test. Then, the broken sections of these filaments are observed by means of a microscope to measure a fretting depth h shown in Fig. 4 when the section of the original steel filament is circle.
  • the fretting depth is evaluated by an index value according to the following equation:
  • the presence or absence of cord breakage is measured by taking out the steel cords from the tire after the running over a distance of 10,000 km under the large bending force.
  • Steel cords are prepared as shown in Table 2 and applied to a carcass ply of a radial tire for truck and bus having a tire size of 11/70R22.5 14PR at an end count of 20.0 cords/5 cm.
  • the fretting depth and cord breakage under large bending force are measured in the same manner as in Example 1 by running such a tire on a drum under the same conditions as in Example 1.
  • steel cord of Comparative Example 3 having a layer twisting structure of 1+6+12+1 and a wrap steel filament of Z-lay (control)
  • steel cord of Comparative Example 4 having a layer twisting structure of 1+6+12 and no wrap steel filament
  • steel cord of Example 2 having a layer twisting structure of 1+6+12+1 and a wrap steel filament of S-lay according to the invention.
  • Table 2 The measured results are shown in Table 2.
  • the twisting pitch of the core is considered to be infinite.
  • Steel cords are prepared as shown in Table 3 and applied to a carcass ply of a radial tire for truck and bus having a tire size of 11/70R22.5 14PR at an end count of 19.8 cords/5 cm.
  • the fretting depth and cord breakage under large bending force are measured in the same manner as in Example 1 by running such a tire on a drum under the same conditions as in Example 1.
  • steel cord of Comparative Example 5 having a layer twisting structure of 3+9+15+1 and a wrap steel filament of S-lay (control)
  • steel cord of Comparative Example 6 having a layer twisting structure of 3+9+15 and no wrap steel filament
  • steel cord of Example 3 having a layer twisting structure of 3+9+15+1 and a wrap steel filament of Z-lay according to the invention.
  • the measured results are shown in Table 3.
  • Steel cords are prepared as shown in Table 4 and applied to a carcass ply of a radial tire for truck and bus having a tire size of 11/70R22.5 14PR at an end count of 31.8 cords/5 cm.
  • the fretting depth and cord breakage under large bending force are measured in the same manner as in Example 1 by running such a tire on a drum under the same conditions as in Example 1.
  • steel cord of Comparative Example 7 having a layer twisting structure of 3+8+1 and a wrap steel filament of Z-lay (control)
  • steel cord of Comparative Example 8 having a layer twisting structure of 3+8 and no wrap steel filament
  • steel cord of Example 4 having a layer twisting structure of 3+8+1 and a wrap steel filament of S-lay according to the invention.
  • the measured results are shown in Table 4.
  • the steel cord according to the invention has such a layer twisting structure that the wrap steel filament is spirally wound around the outermost sheath layer in the same direction as in the steel filament of the outermost sheath layer.
  • the fretting between the steel filament of the outermost sheath layer and the wrap steel filament is decreased and also the lowering of tensile load in the steel filaments of the cord becomes equal to improve the cord life, so that the tire durability can considerably be improved.

Landscapes

  • Ropes Or Cables (AREA)
  • Tires In General (AREA)
EP19930303148 1992-04-27 1993-04-22 Stahlseile zur Verstärkung elastomerer Erzeugnisse und radialer Luftreifen Expired - Lifetime EP0568271B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP10774292 1992-04-27
JP107742/92 1992-04-27

Publications (2)

Publication Number Publication Date
EP0568271A1 true EP0568271A1 (de) 1993-11-03
EP0568271B1 EP0568271B1 (de) 1996-06-19

Family

ID=14466812

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930303148 Expired - Lifetime EP0568271B1 (de) 1992-04-27 1993-04-22 Stahlseile zur Verstärkung elastomerer Erzeugnisse und radialer Luftreifen

Country Status (3)

Country Link
EP (1) EP0568271B1 (de)
DE (1) DE69303222T2 (de)
ES (1) ES2090867T3 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2795751A1 (fr) 1999-06-29 2001-01-05 Michelin Soc Tech Cable d'acier multicouches pour carcasse de pneumatique
EP1388488A1 (de) * 2002-08-07 2004-02-11 Otico Verstärkungskabel für Gummi- Raupenkette
US7380579B2 (en) * 2001-12-07 2008-06-03 Michelin Recherche Et Technique S.A. Metal cable usable in a tire carcass reinforcement
JP2012172291A (ja) * 2011-02-24 2012-09-10 Bridgestone Corp ゴム物品補強用スチールコードおよびゴム−スチールコード複合体

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB720149A (en) * 1952-06-17 1954-12-15 Dunlop Rubber Co Improvements in or relating to pneumatic tyres
EP0373595A1 (de) * 1988-12-16 1990-06-20 Sumitomo Electric Industries, Ltd. Stahlkabel zum Verstärken von Kautschuk
EP0488735A1 (de) * 1990-11-29 1992-06-03 Bridgestone Corporation Stahlcord zur Gummiverstärkung und der Verstärkung radialer Luftreifen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB720149A (en) * 1952-06-17 1954-12-15 Dunlop Rubber Co Improvements in or relating to pneumatic tyres
EP0373595A1 (de) * 1988-12-16 1990-06-20 Sumitomo Electric Industries, Ltd. Stahlkabel zum Verstärken von Kautschuk
EP0488735A1 (de) * 1990-11-29 1992-06-03 Bridgestone Corporation Stahlcord zur Gummiverstärkung und der Verstärkung radialer Luftreifen

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2795751A1 (fr) 1999-06-29 2001-01-05 Michelin Soc Tech Cable d'acier multicouches pour carcasse de pneumatique
US7380579B2 (en) * 2001-12-07 2008-06-03 Michelin Recherche Et Technique S.A. Metal cable usable in a tire carcass reinforcement
EP1388488A1 (de) * 2002-08-07 2004-02-11 Otico Verstärkungskabel für Gummi- Raupenkette
FR2843361A1 (fr) * 2002-08-07 2004-02-13 Otico Cable de renforcement pour chenille souple sans fin
JP2012172291A (ja) * 2011-02-24 2012-09-10 Bridgestone Corp ゴム物品補強用スチールコードおよびゴム−スチールコード複合体

Also Published As

Publication number Publication date
EP0568271B1 (de) 1996-06-19
ES2090867T3 (es) 1996-10-16
DE69303222T2 (de) 1996-12-05
DE69303222D1 (de) 1996-07-25

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