Magnetic self-zipping zipper with different magnetic pull-in forces

A magnetic self-zipping zipper comprising a first end portion, a second end portion and a middle portion along a longitudinal direction of the zipper, and comprising a plurality of magnetic elements of a first type magnetic element and a second type magnetic element, being arranged in a row along the longitudinal direction of the zipper, with the first type magnetic element having a greater pull-in force than the second type magnetic element, wherein the first end portion and the second end portion of the zipper each have at least one of the first type magnetic element but have none of the second type magnetic element, while the middle portion of the zipper comprises both the first type magnetic elements and the second type magnetic elements with 10%-40% of the magnetic elements being the first type and 60%-90% being the second type,

• wherein each of the magnetic elements comprises two pole elements:
• a N-pole element and an S-pole element, and the first type magnetic element comprises two pole elements each of which is a magnetic force concentrated structure of a predetermined design and the second type magnetic element comprises a pole element which is an iron piece, and
• wherein each of the N-pole element and the S-pole element of the first type magnetic element comprises a magnetic ring, a circular iron plate and a protruding portion, the protruding portion being formed by punching on the circular iron plate, the magnetic ring being sleeved on the protruding portion, an inner wall of the magnetic ring has a gap with an outer wall of the protruding portion.