Research On Adaptive Technology In The Numerical Simulation Of Cold Ring Rolling

Cold ring rolling is one of the advanced technologies in producing seamless rings of high quality. The control of ring forming process is very complex for the static, kinematical and dynamic factors have influence on cold ring rolling. Simulating the cold ring rolling process by finite element method can solve the problems of time and labor consuming and low reliability exsiting in the traditional empirical and trial methods. Therefore, it provides an effective tool for comprehensive analysis and process planning of cold ring rolling. With the development of finite element technology, the requirements for automation, precision and efficiency of finite element simulation have become higher and higher. Thus, mesh generation of high quality has become one of the key technologies in the finite element simulation.This research is the important content for the project named as"Research on plastic forming mechanism and technical equipments of cold ring rolling", which is sponsored by NSF. The main task is to implement adaptive mesh refinement and remesh, and to provide reliable meshes for the simulation of cold ring rolling to ensure the accuracy and efficiency of the simulation.This paper analyzes the traditional adaptive finite element method and hexahedral mesh generation method, and puts forward an adaptive mesh refinement and remesh algorithm for the finite element simulation of cold ring rolling.An adaptive mesh refinement activation criteria has been established based on the geometric features of the model. The mesh density is automatically controlled according to the mesh distortion and interference between elements and rollers. The mesh generation method directly divides the original mesh into eight pieces. During the generation process, topological relations between new meshes and original meshes have been recomposed, following the harmonious refinement rule. The field variables of new elements and nodes are distributed and adjusted by averaging method through recording the relationship between the refined nodes and original nodes.Based on analyzing the mesh distortion and the error caused by geometrical discretization of ring parts and rollers, a remesh activation criteria has been put forward according to the discrete error of space domain. Considering the features of cold ring rolling, the new mesh is generated by an improved grid-based algorithm through establishing standard ring grids. The field variables inheritance between the new and original meshes is accomplished by variable smoothing and mapping transformation.Finally, the validity of the adaptive mesh refinement and remesh algorithm is proved by computation examples.