Numerical Simulation And Blank Design Of Welding Neck Flange In Radial Ring Rolling Process

Welding neck flange refers to the flange with the neck and circular tube transition, which is designed to be joined to the pipe by butt welding. It is widely used in the welding of pressure vessels and piping. The radial ring rolling is a forming process of reducing ring thickness, enlarging the diameter, deforming the cross section contour by the ring rolling machine.Welding neck flange radial ring rolling process is complex, and understanding the forming law of welding neck flange, realizing the influence of blank structure size on the quality of ring rolling, reducing and avoiding the occurrence of rolling defects play an important engineering rule in improving the quality of welding neck flange rings.In this paper, the DN1000-1.6-M24-I type welding neck flange is studied. It carried out radial ring rolling theoretical analysis and numerical simulation, the blank designing. The main research contents and achievements are as follows:(1) Formulation of DN1000-1.6-M24-I type welding neck flange radial rolling process. Based on the parameters analysis of DN1000-1.6-M24-I type welding neck flange, formulation of ring rolling is made, and in accordance with the principle of the constant volume and shape similarity, the size of the blank is calculated. In the same time, we calculated the range of feeding speed and rotate speed of the given flange based on ring rolling bite and forging, determining the mandrel feed curve by the growth curve of outer diameter. According to the constant angle, the guide roll trace is made and the ring rolling strategy is formulated.(2) Numerical simulation of DN1000-1.6-M24-I type welding neck flange in radial rolling Process. According to the above ring rolling strategy, the numerical simulation of DN1000-1.6-M24-type is conducted. Through the analysis and comparison of the non-guiding rolling and rolling operating mode in radial ring rolling, the important role of rolling is proved. Through the simulation of rolling mode, the equivalent stress cloud, equivalent strain cloud as well as the roll force curve in the ring rolling process are obtained. By analyzing the occurrence and development of plastic deformation, the author elaborates the reason of warping and sufficient dissatisfaction and other defects generated during the rolling process. By summarizing the flow law of metal, a conclusion is drawn that the neck of blank has a tendency to flow toward the large transverse during the rolling process.(3) Blank designing of DN1000-1.6-M24-I type welding neck flange. The author, taking the DN1000-1.6-M24-I type as object, basing on the analysis of warping, sufficient dissatisfaction and metal flow, determines the principle of blank design and designs four kinds of programs with different structural dimensions. By analyzing the influence of the shape and size of the flange blank on the quality of ring rolling forming, a conclusion is made that the smaller the transverse flow of metal is, the easier for it to fill into the cavity. After the comprehensive comparison of four programs in several aspects such as the filling condition in the metal cavity, the rolling roll force, warping, the degree of difficulty in forming the blank, one respectively ideal is ultimately determined. It will provide basis and guidance for blank design of welding neck flange radial rolling ring.