Boyko Y. Perfection of forming methods of welded cylindrical blanks when profiling and longitudinal reduction with upsetting.

The dissertation is devoted to the task solving technology perfection of forming thin sheet cylindrically welded blanks by removing deformation localization preceding destruction. The reason for destruction of weld and adjacent area during sheet forming operations is found by the methods of macro-, micro- and factographical analysis. Technological methods and techniques of increasing deformability of a blank weld during its forming, before it and after forming have been systemized, generalized and presented. The method of calculation of technological parameters of profiling and upsetting is developed with the longitudinal reduction of the welded cylindrical blanks. It helps to solve differential equations of motion of the deformed shell by the method of finite differences. The method involves comparison of arising tensions and deformations with the extremal ones by which localization of deformations takes place preceding destruction, and maximum allowable deformation resulting in destruction. Stressed state schemes are determined which provide the minimal variation in wall thickness of wheel rims being profiled. The maximum allowable deformations of welded cylindrical blanks at expansion and reduction are determined and practical recommendations for removal of deformation localizations preceding destruction at profiling and longitudinal reduction are given. The empiric method for determination of destroying deformations of a welded cylindrical blank under uniaxial and biaxial tension when forming is developed.