A: This is an old problem, thin rectangular tube.

Also known as a square tube, one side of the bend is always in tension and the other side is in compression. Both sides of the bend at 90 degrees are stretched above and compressed below, so it is very difficult to bend without wrinkling. The specific method is red bending. That is, insert the square steel with the same shape as the bending moment in the rectangular tube, pay attention to the fact that the bending part is divided into at least four pieces, use a planer to plane the corresponding angle on the shape-taking block, spot-weld it in four directions after insertion, then burn it red and bend it on the fixture. Because there is conformal square steel in the thin rectangular tube, there will be no wrinkles. Even if there are small wrinkles, the plastic surgery industry can easily tidy them up while they are hot.

The problem is to remove the module. The module stuck in the thin rectangular tube is not easy to take out. If necessary, please add QQ 12507 10729.