20*20MM square pipe, wall thickness 1.0MM, minimum bending radius of coreless elbow R 72mm, minimum bending radius of through-core elbow R36mm, and the above deformation rate shall not exceed 8%;

20MM round tube, wall thickness of 0.8MM, minimum bending radius of coreless elbow R76mm；; The minimum bending radius of the through-core elbow is R30mm, and the above deformation rate does not exceed 8%;

For example, when the pipe diameter of the material is 60mm and the pipe wall is thick, the bending radius r can be reduced to R 1D for both coreless elbows and through-core elbows! When the pipe wall is thicker and thinner, the bending radius r will be larger!