This process can avoid the phenomenon that the convex edge of the pipe wall becomes thinner under tension and the concave edge of the pipe wall becomes thicker under pressure when the traditional bending process is formed. Elbows with uniform wall thickness, small radius (R≈D) and thin wall (t/D≈0.0 15) 180 can be manufactured by this process, which is impossible for other elbow bending processes. If the process parameters are designed reasonably, the process can ensure that the wall thickness of each part remains unchanged during the bending process, that is, it is always equal to the wall thickness of the straight tube blank before deformation. By adopting this process, elbows with the same diameter of 45, 90, 180 and other bending angles can be made on the same horn mandrel at one time, and the production efficiency is high.

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