Numerical and experimental research of the process of reducing the diameter of a S355J2G2W steel pipe by necking

The article presents the results of research the process of reducing the diameter of pipe ends using the necking method, which are applied to the ends of pressure hoses. The aim of the research was to determine the possibility of reducing the diameter of the S355J2G2W steel pipe by cold necking. The research was carried out using numerical analysis, which was verified experimentally. The software Simufact.forming was used for numerical research of the pipe endnecking process. Experimental tests were carried out using specially designed and made dies and a hydraulic press. As a result of the tests, we determined the pushing force for various friction conditions and the clamping force of the die for four types of grease. The article also presents experimental results of measurements of wall thickness of the pipe being reduced (diameter before and after leaving the die). The test results showed a large influence of the type of grease on: upsetting and elongation of the pipe, flow and the quality of the material surface. The test results showed the effect of the cone angle of the standard die made on the buckling phenomena during the necking process. On the basis of the conducted research, tools for changing the diameter of pipes with theoretically unlimited length were designed. (paper)