Classifications

• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B9/00—Binding or sealing ends, e.g. to prevent unravelling
• • 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
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/10—Rope or cable structures
  • D07B2201/104—Rope or cable structures twisted
  • D07B2201/106—Pitch changing over length
• • 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
  • D07B2201/2026—Pitch changing over length
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2401/00—Aspects related to the problem to be solved or advantage
  • D07B2401/20—Aspects related to the problem to be solved or advantage related to ropes or cables
  • D07B2401/2015—Killing or avoiding twist

Definitions

• the invention relates to a steel cord without flare and to a method of
• Flare is the phenomenon that after cutting of a steel cord spreading of the filament ends or strand ends is observed. Due to the springy nature of high-carbon steel filaments, residual torsions either on cord level or on filament level or on both are present and cause the spreading if no precautions are taken.
• a steel cord having two ends and comprising steel filaments. At least some of the steel filaments are twisted along the length of the steel cord - except for a local region at at least one of the two ends - with a cord lay length L c .
• the steel cord has been additionally cold twisted, i.e. cold over-twisted, in a local region at at least one of the two ends in the same twisting direction of the filaments with the cord lay length L c , so that locally the steel filaments with an original lay length L c have a lay length that is less than 60%, e.g. less than 45%, e.g. less than 30%, e.g. less than 20% of the cord lay length L c in order to avoid flare.
• a local region at at least one of the two ends means that the local region comprises the end of the steel cord or is very close to the steel cord end.
• the invention has the advantage that no other material needs to be added and that welding and any other heat treatment is be avoided.
• the invention is a simple measure.
• the over-twisted steel cord end according to the invention has also shown to be more robust than a welded or burnt steel cord end. Indeed, in case the welded or burnt steel cord end hits a hard material or a spool, one or more individual filaments may become loose due to the brittleness introduced during with welding. This is not the case with an over-twisted steel cord end.
• the local region has a length that is at least one time, preferably two or three or more times the cord lay length l_c. Usually the length of the local region corresponds to a few centimetre.
• the invention is particularly relevant for steel cords comprising filaments that have a different torsion saturation level.
• the torsion saturation level of a steel filament is the level at which the residual torsions no longer increase despite the increasing number of applied torsions.
• the torsion saturation level of a steel filament is dependent upon the filament diameter, the tensile strength and the filament material, i.e. the steel composition. These steel cords often have flare, if no appropriate measures are taken.
• tensile strength levels are normal tensile strength, high-tensile strength, super-high-tensile strength and ultra-high-tensile strength;
• - a high-tensile strength has values ranging from 2400 MPa to 3200 MPa
• a super-high-tensile strength has values ranging from 3200 MPa to 3800 MPa
• - an ultra-high-tensile strength has values ranging from 3800 MPa to 4500 MPa
• composition is different from the second steel composition; examples can be a steel composition for normal tensile strength with typically a carbon content of about 0.70 weight per cent and a steel composition for higher tensile strengths with typically a carbon content of 0.80 weight per cent and higher and possibly with micro alloying elements such as chromium in amounts greater than 0.20 weight per cent.
• the invention is particularly appropriate for small steel cords, i.e. steel cords with a limited number of steel filaments, e.g. between two and nine, e.g. between two and six and with filament diameters below 0.40 mm, e.g. below 0.30 mm.
• the invention has proved to be particularly useful for a steel cord with a core group and a sheath group.
• the core group comprises core steel filaments.
• the sheath group comprises sheath steel filaments.
• the core steel filaments are untwisted or have a lay length greater than 300 mm - except in the local region.
• the sheath group and the core group are twisted around each other with a cord lay length - except in said local region. This cord lay length is much smaller than 300 mm, e.g. smaller than 100 mm.
• the core steel filaments may have a diameter di and the sheath filaments a diameter 02, where di is substantially different from 02. For example, di is greater than 02.
• the core group may have two to four steel filaments.
• the sheath group may have one to six steel filaments.
• a spool filled with a steel cord according to the first aspect of the invention.
• the local region with the over-twisting is situated at full spool. So only one steel cord end, namely the steel cord end at full spool (not the steel cord end at empty spool) needs to be over-twisted. The reason is that the steel cord end at full spool is the one which is first unwound and led to inserts.
• a method of manufacturing a steel cord according to the first aspect comprises the following steps:
• Figure 1 illustrates the prior art practice of welding.
• Figure 2 illustrates the invention on particular steel cord.
• Figure 3 illustrates the general principle of the invention.
• Figure 1 is a longitudinal view of a steel cord 10 with a core group of three steel filaments 12 with a diameter of 0.265 mm and a sheath group of three steel filaments 14 with a diameter of 0.17 mm.
• the lay length Lc of the cord is 14 mm.
• one end 16 of the steel cord 10 has been burnt to weld the individual ends of the steel filaments 12, 14 together to avoid spread.
• Figure 2 is a longitudinal view of a steel cord 20 with a core group of three steel filaments 22 with a filament diameter of 0.265 mm and a sheath group of three steel filaments 24 with a filament diameter 0.17 mm.
• the cord lay length is 14 mm.
• one end of the steel cord 20 has been over-twisted over a local region 26 of about 3 cm to have locally a lay length of only 3.5 mm.
• Other specific examples are:
• Figure 3 illustrates the general principle of the invention.
• Figure 3 is a longitudinal view of a steel cord 30 with steel filaments 32.
• the lay length of the steel cord is L c . At one end, over a local region /, the lay length has been reduced to L e to avoid flare.
• the steel composition of steel cords adapted for the reinforcement of rubber products such as tyres is along the following lines: a carbon content (% C) ranging from 0.60% to 1 .20%, e.g. 0.80% to 1 .1 %;
• a manganese content (% Mn) ranging from 0.10% to 1 .0%, e.g. from 0.20% to 0.80%;
• a silicon content (% Si) ranging from 0.10% to 1 .50%, e.g. from 0.15% to 0.70%;
• Steel filaments adapted for the reinforcement of tyres typically have filaments with a final diameter ranging from 0.05 mm to 0.60 mm, e.g. from 0.10 mm to 0.40 mm.
• filament diameters are 0.10 mm, 0.12 mm, 0.15 mm, 0.175 mm, 0.18 mm, 0.20 mm, 0.22 mm, 0.245 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.40 mm.
• Steel cords adapted for the reinforcement of rubber usually have a coating which promotes the adhesion with rubber such as a brass coating or a ternary alloy coating.

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• Ropes Or Cables (AREA)
• Tires In General (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2015
  • 2015-09-16 CN CN201580057795.2A patent/CN107002356B/zh active Active
  • 2015-09-16 EP EP15763032.8A patent/EP3212839A1/en not_active Withdrawn
  • 2015-09-16 BR BR112017007522-9A patent/BR112017007522B1/pt active IP Right Grant
  • 2015-09-16 WO PCT/EP2015/071205 patent/WO2016066319A1/en active Application Filing

Non-Patent Citations (2)

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