Breaking by bending of shaped ends of steel fuel pipes in low cycle material fatigue mode

Abstract

Technology and equipment for breaking the sharpened ends of fuel pipes with bending during coiled drawing on a self-aligning mandrel have been developed. A brief overview of the methods for cutting round bars and pipes is presented, their main advantages, disadvantages and the scope of application are considered. It is suggested to use the fatigue fracture effect for bending breakage of sharpened ends of steel thick-walled pipes. The research problem is to investigate the process under cyclic loads. The possibility of applying the known provisions of calculating theory of strength analysis for low-cycle fatigue for this process is tested. A comparative assessment of theoretical and experimental data is given and their significant difference is established. New calculated dependences are proposed and are in good agreement with the experimental data. The theoretical estimation of the breakage process productivity has been carried out. Different variants of breakage device constructions with the analysis of their work peculiarities have been proposed. Based on the results of the analysis for implementing continuous process of breaking the pointed ends of thick-walled fuel pipes in drawing in coils and a diagram of the mechanism for breaking pipe ends with its supply from coils are selected. The pipes samples obtained by brittle cyclic bending are presented. © 2021 Elsevier B.V.. All rights reserved.