Steel cord and manufacturing process therefor

A manufacturing method for a steel cord, wherein, the steel cord comprises:

• a steel core wire located in a center and having a diameter of d;
• M sheath-layer steel wires arranged around the steel core wire in the center, tangent to the steel core wire, and having a diameter of d1, at least two gaps L existing between the M sheath-layer steel wires, wherein M is 4;
• d, d1, and L satisfy a relationship:
• 0.420<(d/d1)<0.800;
• d1 is between 0.20 mm and 0.44 mm;
• and
• L≥0.0008 mm;
• wherein,
• in a twisting process, a steel core wire and M sheath-layer steel wires are simultaneously unwound, an unwinding tension of the sheath-layer steel wires being equal, and the unwinding tension of the steel core wire being greater than that of each sheath-layer steel wire;
• and the steel core wire is placed in the center, and the M sheath-layer steel wires are uniformly distributed at 360° and bundled together around the steel core wire for twisting.