Preparation method of three-cavity structure rolling profile

The invention provides a preparation method of a three-cavity structure rolling profile, which comprises the following steps of: carrying out rolling bending on a steel belt to form a first bending angle structure and a second bending angle structure; carrying out roll bending on the bent angle structure to form a third bent angle structure and a fourth bent angle structure; carrying out roll bending on the first to fourth corner structures to form a fifth corner structure and a sixth corner structure; carrying out roll bending on the third to sixth bend angle structures to form seventh and eighth bend angle structures; the seventh and eighth corner structures are subjected to roll bending; carrying out roll bending to form a ninth to eleventh bend angle structure; the tenth and eleventh corner structures are subjected to roll bending; laser welding is conducted on the first end attaching position and the second end attaching position; back bending roll bending is carried out; and carrying out laser welding o