JCOE is a pipe making technology for the production of large diameter thick wall steel pipes. It mainly adopts the production process of double-sided submerged arc welding. The products go through multiple processes such as milling, pre bending, bending, seam closing, internal welding, external welding, straightening, and flat end. The forming process can be divided into N+1 steps (N is a positive integer). The steel plate is automatically fed laterally and bent according to the set step size to realize the numerical control progressive J-C-O forming. The steel plate enters the forming machine horizontally, and under the push of the feeding trolley, the first stage of multi-step bending with N/2 steps is carried out to realize the “J” forming of the front half of the steel plate; In the second stage, firstly, the steel plate formed by “J” shall be sent to the specified position in the transverse direction rapidly, and then the unformed steel plate shall be bent in multiple steps of N/2 from the other end to realize the forming of the second half of the steel plate and complete the forming of “C”; Finally, the lower part of the “C” type tube blank is bent once to realize the “O” forming. The basic principle of each stamping step is three-point bending.