Supplementary reply:

The diameter of the U-shaped pipe is 150mm, and the bending radius is 75 mm This bending radius is too small, and the bending radius should be at least equal to or greater than the outside diameter d of the pipe. The specification of the pipe is very large. If you want to get a suitable bend, you must first fill the pipe with sand and heat it before pressing it. The heating temperature is controlled between 150~250℃. When aluminum tubes are hot-pressed, the temperature is not easy to control, and the technical requirements for operation and processing are high. The bending of aluminum tube is slightly wrinkled, which is also technically allowed.