US 12,257,867 B2
Steel cord for rubber reinforcement
Aijun Zhang, Jiangyin (CN)
Assigned to NV Bekaert SA, Zwevegem (BE)
Appl. No. 18/268,501
Filed by NV Bekaert SA, Zwevegem (BE)
PCT Filed Nov. 30, 2021, PCT No. PCT/EP2021/083627
§ 371(c)(1), (2) Date Jun. 20, 2023,
PCT Pub. No. WO2022/135850, PCT Pub. Date Jun. 30, 2022.
Claims priority of application No. PCT/CN2020/138103 (WO), filed on Dec. 21, 2020.
Prior Publication US 2024/0075772 A1, Mar. 7, 2024
Int. Cl. B60C 9/20 (2006.01); D07B 1/06 (2006.01)
CPC B60C 9/2006 (2013.01) [D07B 1/0633 (2013.01); B60C 2009/2077 (2013.01); B60C 2009/2096 (2013.01); D07B 2205/3025 (2013.01); D07B 2501/2046 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A steel cord, said steel cord having a construction comprising an outer layer and an inner strand surrounded by and adjacent to said outer layer, said inner strand comprising at least one steel filament with a number of N1, said at least one steel filament of said inner strand having an average diameter of d1 expressed in mm, said outer layer comprising steel filaments with a number of N2, said steel filaments of said outter layer having an average diameter of d2 expressed in mm, wherein said inner strand has a torque T1, said outer layer has a torque T2, T1 and T2 satisfy the following formulas:
T1=G×RT1×π2×D12×d12×N1/16000,
T2=G×RT2×π2×(D12+D22)×d22×N2/16000,
|T1+T2|<60,
wherein,
D1 is the theoretical diameter of the inner strand while D2 is the theoretical diameter of the steel cord, D1 and D2 are expressed in mm,
RT1 is the residual torsion of the inner strand while RT2 is the residual torsion of the outer layer expressed in the number of turns per meter in “+” if in clockwise direction or “−” if in anticlockwise direction,
G is 80000 N/mm2,
and the absolute value of RT2 is less than 2 turns per meter and no less than 0.05 turns per meter, and the absolute value of RT1 is no less than 0.05 turns per meter.