Multi-strand steel cord having a core and peripheral strands surrounding the core

摘要

A steel cord (10) has a diameter D and includes a core strand (12) and up to nine peripheral strands (14) surrounding the core strand. The core strand (12) has a diameter D1 and the peripheral strands (14) have a diameter D2. The ratio core strand diameter to peripheral strand diameter D1/D2 is greater than a predetermined value in order to enable rubber penetration. Each strand has a center of one or more center filaments (16, 22) and two or more layers of filaments (18, 20, 24, 26) surrounding the center. The twist angle of a radially outer layer is smaller than the twist angle of a radially inner layer of the same strand. A first free space (28) ranging from 0.0015xD to 0.0075xD is provided in at least the core strand between each pair of filaments (18) of the radially most inner layer.