Compact steel cord

Abstract

A compact steel cord is provided. The cord includes a core-filament I steel wire with a diameter of d0, and four middle-layer M steel wires with a diameter of d1 and eight outer-layer O steel wires with a diameter of d2 that are twisted around the core-filament I steel wire in the same lay direction and the same lay length. Gaps L are reserved between the outer-layer O steel wires, an average width of the gaps L is not smaller than 0.02 mm, and the total size of the gaps L is larger than d0 and smaller than d1. The steel cord of a stable structure can be obtained by controlling the proportion of the sizes of all layers of monofilaments, the rubber coating performance of a tire cord can also be improved, the corrosion resistance, fatigue resistance, impact resistance and adhesion retention of a tire are improved.

Claims

1. A compact steel cord, comprising a core-filament I steel wire with a diameter of d0, and four middle-layer M steel wires with a diameter of d1 and eight outer-layer O steel wires with a diameter of d2 that are twisted around the core-filament I steel wire in a same lay direction and a same lay length, wherein gaps L are reserved between the outer-layer O steel wires, an average width of the gaps L is not less than 0.02 mm, and a total size of the gaps L is larger than d0 and smaller than d1; tensile strengths of the core-filament I steel wire, the middle-layer M steel wire and the outer-laver O steel wire are respectively Ts1, Ts2, and Ts3, which satisfy the following relationships:
50 Mpa<(Ts2?Ts1)<400 Mpa; and
0 Mpa?(Ts3?Ts2)<400 Mpa.

2. The compact steel cord according to claim 1, wherein, the outer-layer O steel wires comprise four first outer-layer O steel wires tangent to any two adjacent middle-layer M steel wires and other four second outer-layer O steel wires, and the second outer-layer O steel wires are located between two adjacent first outer-layer O steel wires.

3. The compact steel cord according to claim 1, wherein, d0, d1, and d2 satisfy the following relationships:
0.41<(d0/d1)<0.64;
1<(d2/d1)<1.32; and d0 is between 0.06 mm and 0.20 mm.

4. The compact steel cord according to claim 3, wherein, d0, d1, and d2 further satisfy the following relationships:
0.42<(d0/d1)<0.64;
1.13<(d2/d1)<1.32; and d0 is between 0.08 mm and 0.18 mm.

5. The compact steel cord according to claim 1, wherein, TS1, Ts2, and Ts3 satisfy the following relationships:
50 Mpa<(Ts2?Ts1)<150 Mpa; and
0 Mpa?(Ts3?Ts2)<150 Mpa.

6. The compact steel cord according to claim 1, wherein, a wire rod used for the core-filament I steel wire comprises the following components in percentage by weight of the wire rod: carbon?0.86%, manganese in a range of 0.30-0.60%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, and ferrum as a remaining component.

7. The compact steel cord according to claim 1, wherein, a wire rod used for the middle-layer M steel wires and the outer-layer O steel wires comprises the following components in percentage by weight of the wire rod: carbon in a range of 0.60-1.02% , manganese in a range of 0.30-0.70%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, chromium no more than 0.35%, and ferrum as a remaining component.

8. The compact steel cord according to claim 2, wherein, a wire rod used for the core-filament I steel wire comprises the following components in percentage by weight of the wire rod: carbon?0.86% , manganese in a range of 0.30-0.60%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, and ferrum as a remaining component.

9. The compact steel cord according to claim 3, wherein, a wire rod used for the core-filament I steel wire comprises the following components in percentage by weight of the wire rod: carbon?0.86% , manganese in a range of 0.30-0.60%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, and ferrum as a remaining component.

10. The compact steel cord according to claim 4, wherein, a wire rod used for the core-filament I steel wire comprises the following components in percentage by weight of the wire rod: carbon?0.86% , manganese in a range of 0.30-0.60%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, and ferrum as a remaining component.

11. The compact steel cord according to claim 2, wherein, a wire rod used for the middle-layer M steel wires and the outer-layer O steel wires comprises the following components in percentage by weight of the wire rod: carbon in a range of 0.60-1.02% , manganese in a range of 0.30-0.70%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, chromium no more than 0.35%, and ferrum as a remaining component.

12. The compact steel cord according to claim 3, wherein, a wire rod used for the middle-layer M steel wires and the outer-layer O steel wires comprises the following components in percentage by weight of the wire rod: carbon in a range of 0.60-1.02% , manganese in a range of 0.30-0.70%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, chromium no more than 0.35% and ferrum as a remaining component.

13. The compact steel cord according to claim 4, wherein, a wire rod used for the middle-layer M steel wires and the outer-layer O steel wires comprises the following components in percentage by weight of the wire rod: carbon in a range of 0.60-1.02% , manganese in a range of 0.30-0.70%, silicon in a range of 0.15-0.30%, phosphorus no more than 0.030%, sulfur no more than 0.030%, chromium no more than 0.35%, and ferrum as a remaining component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional structure diagram of a steel cord of a 1+4+8 structure designed by the present invention.

(2) In the figure, 1core-filament I steel wire, 2middle-layer M steel wire, 3outer-layer O steel wire, 301first outer-layer O steel wire, 302second outer-layer O steel wire.

DETAILED DESCRIPTION

(3) To make the objective, technical solution, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the embodiments. It is to be understood that the specific embodiments described herein are merely used for explaining the present invention but are not intended to limit the present invention.

(4) The application principles of the present invention are described in detail below with reference to the embodiments.

(5) FIG. 1 is a schematic cross-sectional structure diagram of a steel cord according to the present invention. As can be seen from the drawing, the structure of a compact steel cord includes a core-filament I steel wire 1 with a diameter of d0, and four middle-layer M steel wires 2 with a diameter of d1 and eight outer-layer O steel wires 3 with a diameter of d2 that are twisted around the core-filament I steel wire 1 in the same lay direction and the same lay length. Two adjacent middle-layer M steel wires 2 can either have a gap or be in close contact. Four first outer-layer O steel wires 301 in the eight outer-layer O steel wires 3 are tangent to any two adjacent middle-layer M steel wires, and sink into the gap between the two middle-layer M steel wires 2, and the other four second outer-layer O steel wires 302 are respectively located between two adjacent first outer-layer O steel wires 301.

(6) By adjusting a ratio of d0 to d1 to control the gap between the middle-layer M steel wires, it avoids that the total size of the gaps is larger than the size d0 of the core-filament I steel wire 1 due to aggregation of the middle-layer M steel wires 2, so that the core-filament I steel wire 1 slides to the middle layer M to change the structure. In addition, by adjusting a ratio of d1 to d2 to control a gap between the outer-layer O steel wires 3, on the one hand, it avoids that the total size of the gaps L is larger than the size d1 of the middle-layer M steel wire due to aggregation of the outer-layer O steel wires 3, so that the middle-layer M steel wire slides to the outer-layer O to change the structure; on the other hand, the first outer-layer O steel wires 301 effectively sink and are restricted in the grooves of the middle-layer M steel wires 2, and form circumferentially distributed gaps L with the second outer-layer O steel wires 302.

(7) The steel cord produced by controlling the ratio of all layers of monofilaments of the steel cord can make the outer-layer O steel wires 3 form gaps L with an average gap width of at least 0.02 mm. Considering the relative sliding of the second outer-layer O steel wire 302, at least four of the formed gaps L are larger than 0.025 mm in size, which allows a rubber viscous fluid to penetrate into the M layers of the steel cord smoothly, improving the rubber coating performance of the cord. In addition, by controlling the ratio of all layers of monofilaments, the total size of the gaps L is larger than d0 and smaller than d1, which ensures the stability of the cord structure.

(8) The steel cord according to the present invention is manufactured by the following method: the raw material is a steel wire rod, and the wire rod used for the core-filament I steel wire includes the following components in percentage by weight: C?0.86%, Mn 0.30-0.60%, Si 0.15-0.30%, P no more than 0.030%, S no more than 0.030%, and the balance of Fe. A wire rod used for the middle-layer M steel wires and the outer-layer O steel wires includes the following components in percentage by weight: C 0.60-1.02%, Mn 0.30-0.70%, Si 0.15-0.30%, P no more than 0.030%, S no more than 0.030%, Cr no more than 0.35%, and the balance of Fe. The steel wire is drawn to the required size, so that when the steel cord is made, the tensile strengths Ts1, Ts2, and Ts3 of the core-filament I steel wire, the middle-layer M steel wire, and the outer-layer O steel wire satisfy the following relationships: 50 Mpa<(Ts2?Ts1)<400 Mpa; and 0 Mpa?(Ts3?Ts2)<400 Mpa.

(9) Preferably, 50 Mpa<(Ts2?Ts1)<150 Mpa; and 0 Mpa?(Ts3?Ts2)<150 Mpa.

(10) According to the description above, the present invention manufactures a steel cord with a minimum size ratio of the core-filament I steel wire 1, and parameters of each embodiment are shown in the following table:

(11) TABLE-US-00001 TABLE 1 Size parameters of the steel cord manufactured in Examples 1-6 Unit Example I Example II Example III d0/d1/d2 (?0.01) mm 0.08/0.175/ 0.085/0.20/ 0.10/0.225/ 0.21 0.235 0.27 Cord diameter (?5%) mm 0.85 0.955 1.09 Lay length (?5%) mm 12.0 14.0 15.0 Line density (?5%) g/m 2.99 3.80 4.97 L mm 0.020 0.024 0.025 Example IV Example V Example VI d0/d1/d2 (?0.01) mm 0.11/0.25/ 0.13/0.295/ 0.16/0.33/ 0.30 0.35 0.395 Cord diameter (?5%) mm 1.21 1.42 1.61 Lay length (?5%) mm 16.0 18.0 20.0 Line density (?5%) g/m 6.14 8.41 10.70 L mm 0.027 0.034 0.041

(12) It can be seen from Table 1 that all the gaps L between the outer-layer O steel wires 3 of the steel cords in Examples 1-6 are not smaller than 0.02 mm, which can meet the requirements for gaps in the rubber penetration process, making rubber enter the M layers of the steel cord.

(13) Trial manufacture of cords is carried out according to the method of the present invention, and the performance of steel cords manufactured in Example II, Example III, and Example V are selected for testing, and compared with the performance of the steel cords with the same diameter in the structure in the prior art, the structure of the steel cord in the comparative example can be found in Chinese invention patents CN 209066179 U and CN 1898435 B, and the utility model patent CN 203034291 U. The specific rubber penetration test coating method is: cutting a section of steel cord and placing it in a mold box where rubber is placed, and then coating the other side of the placed steel cord with rubber; after a certain time period of high temperature and high pressure, forming a sample of the steel cord cured in rubber, taking a 25 mm sample, peeling off outer-layer O steel wires, and measuring an approximate length J and width K of an uncoated part of a sheath-layer steel wire, subscripts 1, 2, . . . , and M representing different uncoated parts; calculating an area of uncoated steel wires, dividing it by the total area of all steel wires obtained by multiplying the approximate width of the uncoated parts by 25 mm to obtain the percentage of the uncoated part; and subtracting this percentage from 1 to obtain the rubber coating percentage, i.e., the rubber coating rate Pc. See Formula (1) for details:

(14) $\begin{array}{cc}\mathrm{Pc}=\left[1-\frac{J_1*K_1+J_2*K_2+.Math.+J_M*K_M}{\left(K_1+K_2+.Math.+K_M\right)*25}\right]?100\%& \left(1\right)\end{array}$

(15) The test results are as shown in Table 2:

(16) TABLE-US-00002 TABLE 2 Rubber penetration performance of the steel cords of the examples of the present invention and the comparative examples of the same diameter Comparative Example Example CN 209066179 U Item Unit II 3 ? 0.24/9 ? 0.225 d0 mm 0.085 / d1 mm 0.202 0.241 d2 mm 0.235 0.226 Cord diameter mm 0.958 0.942 Lay direction S/Z S S Lay length mm 13.92 14.10 Line density g/m 3.82 3.992 Fracture load N 1481 1504 Rubber penetration- % 22.1 17.0 coating rate (Pc) Comparative Example Example CN 1898435 B Item Unit III 0.22 + 18 ? 0.20 d0 mm 0.10 0.221 d1 mm 0.226 0.202 d2 mm 0.272 0.201 Cord diameter mm 1.095 1.026 Lay direction S/Z Z Z Lay length mm 15.1 12.36 Line density g/m 5.03 4.89 Fracture load N 2012 1889 Rubber penetration- % 24.2 0 coating rate (Pc) Comparative Example Example CN 203034291 U Item Unit V 3 + 9 + 15 ? 0.225 d0 mm 0.13 0.226 d1 mm 0.293 0.227 d2 mm 0.351 0.226 Cord diameter mm 1.42 1.394 Lay direction S/Z Z Z/Z/Z Lay length mm 17.83 6.31/12.35/17.7 Line density g/m 8.43 8.733 Fracture load N 3026 3212 Rubber penetration- % 26.3 0 coating rate (Pc)

(17) It can be seen from data in Table 2 that under the condition of the same diameter of the cords of the three examples and the comparative examples, the strengths of the same line density are basically the same, and the rubber coating performance of the cords of the examples is better than that of the cords of the comparative examples.

(18) In addition, in this embodiment in Table 2, rubber penetration is not detected using a pressure drop. Because of the eight outer-layer O steel wires of the 1+4+8 structure, four first outer-layer O steel wires 301 are tangent to the adjacent middle-layer M steel wires 2, and sink into the gaps of the middle-layer M steel wires 2, to form four small triangular gaps. The rubber cannot fully penetrate to make the air flow through part of the gaps when the pressure drop is detected.

(19) The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited by the embodiments above. The embodiments above and the descriptions only illustrate the principles of the present invention. Various changes and improvements may be made to the present invention, without departing from the spirit and scope of the present invention. These changes and improvements all fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and equivalents thereof.