EP0168857B1 - Steel cord construction - Google Patents
Steel cord construction Download PDFInfo
- Publication number
- EP0168857B1 EP0168857B1 EP85200930A EP85200930A EP0168857B1 EP 0168857 B1 EP0168857 B1 EP 0168857B1 EP 85200930 A EP85200930 A EP 85200930A EP 85200930 A EP85200930 A EP 85200930A EP 0168857 B1 EP0168857 B1 EP 0168857B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- wires
- pair
- cord
- diameter
- wire
- 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.)
- Expired
Links
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
- D07B1/062—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
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2015—Strands
- D07B2201/2022—Strands coreless
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2207/00—Rope or cable making machines
- D07B2207/20—Type of machine
- D07B2207/204—Double twist winding
- D07B2207/205—Double twist winding comprising flyer
Definitions
- the invention relates to a steel cord for reinforcement of resilient articles, such as rubber vehicle tyres.
- Such cord will generally be a cord with wires having a diameter ranging from 0.03 to 0.80 mm, in general in the range from 0.14 to 0.40 mm, and the steel being in general carbon steel (preferably 0.65 to 0.95% carbon) in its ferritic state, having a tensile strength of at least 2000 N/mm 2 , in some high-tensile applications more than 3000 N/mm 2 , and an elongation at rupture of at least 1 %, preferably about 2%.
- the cord wires will generally further comprise, in order to obtain the necessary rubber adherability for reinforcement purposes, a rubber adherable coating, such as copper, zinc, brass or ternary brass alloy, or a combination thereof, the coating having a thickness ranging from 0.05 to 0.40 micron, preferably from 0.12 to 0.22 micron.
- the coating can also be present in the form of a thin film of chemical primer material for ensuring good rubber penetration and adhesion.
- cord constructions are known in the form of a bundle of four wires, twisted together with a same pitch. This construction is most frequently used in a wire diameter range of 0.14 to 0.40 mm, preferably 0.19 to 0.31 mm, with a twist pitch between 35 and 100 times the wire diameter, for use in truck or passenger car tyres.
- Such cord was normally made in a closed 4x1-configuration, i.e. a cross-sectional configuration where the centres of the wires are arranged in the corners of a square with a side equal to the wire diameter. Such an arrangement is shown in figure 1 of GB-A-2 081 765. This cord however leaves a hollow cavity inside, which is notfilled up with rubber during vulcanizing, and moisture can easily travel lengthwise through this cavity thereby provoking corrosion.
- a closed 2+2-construction was further proposed as an alternative, comprising two strands twisted around each other with a certain pitch p, the first strand comprising two wires, helicoidally deformed and running side by side in parallel with each other without twist around each other, and the second strand comprising two wires twisted around each other with the same pitch p with which this strand is twisted around the first strand.
- This cord although showing good rubber penetration, is however, less good for applications where extra good fatigue resistance is aimed at, and, as is important for fuel consumption, also low tyre weight. Indeed this cord is rather wide, because it is not particularly round, so that then less cords can be laid side by side in a ply, and furthermore the ply is then required to be thicker.
- a steel cord for the reinforcement of resilient articles in the form of a bundle of four wires twisted together with the same pitch, a first pair of said wires comprising two wires of substantially similar diameter, a second pair of said wires each having a diameter not greater than the average diameter of the first pair, a wire of one pair being succeeded by a wire of the other pair along the circumference of the bundle, and is characterized by the fact that, in a stretched condition of the cord, the wires of the first pair are tightly twisted together while each wire of the second pair is spaced from the wires of the first pair.
- the diameter of each of said wires of the second pair is smaller than the average diameter of the first pair, e.g. in a range of 0.6 to 0.85 of said average diameter.
- the wires of the first pair are twisted as tightly as possible, whereas the wires of the second pair are loosely twisted and preferably thinner.
- the cord can hardly elongate any further by tightening its structure because the wires of the first pair are practically completely tight.
- the tow wires of the second pair are loosely twisted and keep a distance, so that rubber penetration is ensured.
- this cord construction shows a sufficient roundness, and these changes in geometry appear not to be at the expense of fatigue resistance, as measured by the Hunter fatigue test.
- the two wires of the first pair must not necessarily have the same diameter. It is sufficient that the diameters be "substantially similar", i.e. in the case of different diameter, the thicker one must not be more than 120% of the diameter of the other one, preferably not more than 110%.
- the wires of the first pair are as tight as possible, so that the structural elongation (i.e. the percentage e of elongation due to the tightening of the structure when passing from the straight unstretched to the stretched condition) be at any rate not more than e m , as given by the formula or preferably, as given by the formula in which D a is the average diameter of these two wires and p the twist pitch.
- this corresponds to saying that the distance between the two wires of the first pair in straight unstretched condition be not more than 0.3, preferably not more than 0.15 times the average diameter of the two wires.
- the spacing of each wire of the second pair, from those of the first pair is in a range from 0.05 to 0.30 of said average diameter of the first pair.
- the lower limit is set by a sufficient guarantee that rubber penetration will be ensured, and the upper limit by the necessity that under normal loads, the two loose wires participate substantially in taking up these loads.
- this spacing means the average spacing along the length.
- the cord is preferably used in its dimension range usable for light truck and passenger car tyres, i.e. with an average diameter of the first pair of wires in the range of 0.14 to 0.40 mm and with a twist pitch ranging from 35 to 80 times the average diameter, as an alternative of the 4x1 cords with 0.25 to 0.38 mm wire diameter.
- Figure 1 shows a cross-sectional configuration of the cord according to the invention, and in stretched condition. It comprises a first pair of steel wires 1 and 2 of a diameter of 0.28 mm and a second pair of steel wires 3 and 4 of a diameter of 0.22 mm.
- the four wires form a bundle of four wires twisted together with a same pitch of 14 mm.
- the wires 1 and 2 are in contact with each other along a contact line, which runs in an axial direction of the cord, perpendicular to the plane of the drawing, through contact point 5 between the two cross-sections. At either side of this contact line, the wires leave two opposite V-shaped or wedge-shaped recesses 6, respectively 7.
- wedge shapes run helicoidally with the pitch of the wires, along the contact line.
- the two other wires 3 and 4 fit these wedge shapes and run helicoidally along these recesses without contacting the wires 1 and 2, but keeping a distance d of about 0.04 mm from each of these wires, this distance being an average over the length of the cord.
- a wire of the pair 1 and 2 therefore alternates with a wire of the pair 3 and 4 along the circumference of the cord.
- the wires 1 and 2 can either be apart or not be apart, according to the helicoidal deformation given to the wires in the twisting process. They are however twisted sufficiently tightly so as not be further apart than a distance of 0.042 mm. For these cord dimensions, this corresponds to a structural elongation from the unstretched to the stretched condition of maximum 0.0636%.
- the cord is made by a process using a conventional double-twister 11 as shown in figure 2.
- the four wires 1, 2, 3 and 4 are unwound from a creel, pass through a guiding plate 12, and converge towards a twisting-die 13 into a bundle. From there, the bundle further travels towards the double-twister 11, where it enters axially through the rotation axis 15 of the twister, over the rotating flyer 16 back to the rotation axis on the other side, where it enters axially into the stationary cradle 17 inside the twister over capstan 19 for winding up on the bobbin 18.
- the bundle is drawn from the unwinding creel through the machine by capstan 19.
- twister twists the four wires 1 to 4 together to a bundle with a pitch depending on the relationship between the traveling speed given by the capstan 19 and the rotation speed of the flyer 16.
- double twister of Figure 2 is of the type with winding-up bobbin inside the twister, it is clear that the type with winding-up bobbin outside the twister can be used in an analogous way.
- the method by which the predeformation is given to the wires 1 to 4 is shown in greater detail on Figure 3. It shows the wires 1, 2, 3, 4 passing through the holes 21, 22, 23, 24 respectively, of the guiding plate 12, which has a circular form.
- the wires 1 and 2 are deformed into a helicoidal form, because the wires rotate around their own axis when passing through the hole: the torsion given to each wire by the double twister 11 is transmitted back through the twisting-die.
- the degree of predeformation of wires 1 and 2 is determined by the distance of the holes 21 and 22 from the centre of the plate, and by the distance of the guiding plate from the twisting-die, as is well known in the art.
- a further possibility of adjusting the predeformation of wires 1 and 2 is provided by making holes 21 and 22, as shown in Figure 3c, in the form of hollow screws, screwed into the plate so as to make the distance between the exit of the hole and the twisting-die adjustable.
- the degree of deformation (openness) of wires 3 and 4 is obtained by the fact that these wires, after leaving holes 23 and 24, slightly diverge and pass over the rim of a deformation wheel 25, from where they suddenly converge towards the twisting-die 13.
- This deformation wheel has an axis 26, screwed in the guiding plate, and the distance from the plate can be changed by rotation of the wheel.
- the degree of deformation of wires 3 and 4 can be adjusted by adjusting this distance.
- Penetration degree is expressed in terms of airflow (liter per hour).
- a cylindrical rubber rod of 220 mm length and 15 mm thickness is formed around 4 axially running cords, by vulcanizing under a pressure of 20 bar under standard conditions. Both ends of the rod are then submitted to a gradually raising pressure difference from 0 to 9 bar and the air flow curve is recorded or calculated by regression analysis.
- the penetration degree is then expressed by the air flow at 4 bar. A large air flow consequently means poor rubber penetration.
- Fatigue resistance is the value in Newton/mm 2 of the fatigue resistance of the cord, as measured by the Hunter rotating-beam fatigue test.
- Cord thickness is the average, over the cord length, of the cord thickness, measured according to the standard ASTM-test D2969-76, i.e.: between two parallel surfaces, having a length of at least the lay length of the pitch, and at three locations where in each two measurements are made in orientation which are 90 degrees apart.
- Diameter fluctuation is half the difference between the maximum and minimum cord thickness, (measured according to the standard test above: i.e. at the location which has the greatest spread between maximum and minimum thickness (and as such a measure of the ovality of the cross-section.
- Breaking load is the tensile load limit where the cord breaks.
- Stiffness in rubber is a value for evaluating tyre wear versus driving comfort. If too high, comfort is low but tyre wear too, and the inverse occurs when the stiffness is too low. A value in the range 100-200 is generally preferred.
- the stiffness value e k is given by the formula in which M,, and Mo are the values, in Newton millimeter, of the Taber Stiffness and the Taber counter Moment respectively, of a cord sample of 75 mm, bent over 15° and unbent in a Taber V-5 Stiffness Tester. The sample is embedded in rubber to form a diameter of 3 mm.
- cord B and the cords which are an embodiment of the invention can well reconcile penetration degree, fatigue resistance and sufficient compactness (as to B to a lower degree). But, what is important: the other necessary properties, such as cord stiffness, are not lost.
- the good penetration degree of cord B was however obtained at the expense of special precautions to avoid tension during vulcanizing, which is not necessary with the cord which is an embodiment of the invention.
Landscapes
- Ropes Or Cables (AREA)
- Laminated Bodies (AREA)
- Reinforced Plastic Materials (AREA)
- Tires In General (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT85200930T ATE32924T1 (de) | 1984-07-20 | 1985-06-13 | Metallseilherstellung. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8418509 | 1984-07-20 | ||
GB848418509A GB8418509D0 (en) | 1984-07-20 | 1984-07-20 | Steel cord construction |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0168857A1 EP0168857A1 (en) | 1986-01-22 |
EP0168857B1 true EP0168857B1 (en) | 1988-03-09 |
Family
ID=10564173
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85200930A Expired EP0168857B1 (en) | 1984-07-20 | 1985-06-13 | Steel cord construction |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP0168857B1 (pt) |
JP (1) | JPS6163792A (pt) |
AT (1) | ATE32924T1 (pt) |
AU (1) | AU574804B2 (pt) |
BR (1) | BR8503450A (pt) |
CA (1) | CA1304263C (pt) |
DE (1) | DE3561828D1 (pt) |
ES (1) | ES296143Y (pt) |
GB (1) | GB8418509D0 (pt) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0342644B1 (en) * | 1988-05-20 | 1996-08-21 | TOYO TIRE & RUBBER CO., LTD . | Pneumatic tire |
ATE91514T1 (de) * | 1988-06-01 | 1993-07-15 | Bekaert Sa Nv | Aufbau eines stahlcords mit hoher zugfestigkeit. |
JPH02242988A (ja) * | 1989-03-15 | 1990-09-27 | Sumitomo Electric Ind Ltd | ゴム補強用スチールコード |
US5285623A (en) * | 1989-04-03 | 1994-02-15 | N.V. Bekaert S.A. | Steel cord with improved fatigue strength |
EP0493410B1 (en) * | 1989-09-18 | 1994-04-13 | N.V. Bekaert S.A. | Open cord structure |
JP2523397Y2 (ja) * | 1990-01-26 | 1997-01-22 | 東京製綱株式会社 | スチールコード |
IT1277689B1 (it) | 1995-12-21 | 1997-11-11 | Pirelli | Cordicella metallica di rinforzo da impiegarsi particolarmente in manufatti compositi a matrice elastomerica procedimento ed apparato |
KR100680159B1 (ko) | 1998-12-24 | 2007-02-08 | 피렐리 타이어 소시에떼 퍼 아찌오니 | 강화 엘라스토머 제품, 특히 타이어용의 금속 코오드 제작방법 및 장치 |
BRPI0621667B1 (pt) | 2006-05-10 | 2016-11-29 | Bekaert Sa Nv | cordonel de metal, processo para fabricar um cordonel de metal, e, aparelho para fabricar um cordonel de metal |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3006488A1 (de) * | 1980-02-21 | 1981-08-27 | Uniroyal Englebert Reifen GmbH, 5100 Aachen | Fahrzeugluftreifen |
JPS6049421B2 (ja) * | 1980-08-11 | 1985-11-01 | 株式会社ブリヂストン | 金属コ−ドとゴムの複合体 |
JPS58191609A (ja) * | 1982-04-30 | 1983-11-08 | Kanai Hiroyuki | スチ−ルコ−ド |
-
1984
- 1984-07-20 GB GB848418509A patent/GB8418509D0/en active Pending
-
1985
- 1985-06-13 DE DE8585200930T patent/DE3561828D1/de not_active Expired
- 1985-06-13 EP EP85200930A patent/EP0168857B1/en not_active Expired
- 1985-06-13 AT AT85200930T patent/ATE32924T1/de not_active IP Right Cessation
- 1985-06-26 CA CA000485320A patent/CA1304263C/en not_active Expired - Fee Related
- 1985-07-16 AU AU45043/85A patent/AU574804B2/en not_active Ceased
- 1985-07-18 JP JP60157098A patent/JPS6163792A/ja active Pending
- 1985-07-19 BR BR8503450A patent/BR8503450A/pt not_active IP Right Cessation
- 1985-07-19 ES ES1985296143U patent/ES296143Y/es not_active Expired
Also Published As
Publication number | Publication date |
---|---|
EP0168857A1 (en) | 1986-01-22 |
ES296143U (es) | 1987-12-01 |
AU4504385A (en) | 1986-01-23 |
GB8418509D0 (en) | 1984-08-22 |
DE3561828D1 (en) | 1988-04-14 |
AU574804B2 (en) | 1988-07-14 |
JPS6163792A (ja) | 1986-04-01 |
ES296143Y (es) | 1988-05-16 |
BR8503450A (pt) | 1986-04-15 |
CA1304263C (en) | 1992-06-30 |
ATE32924T1 (de) | 1988-03-15 |
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