Protsenko P. Metal spinning process developed for manufacturing helical tubes

The thesis is devoted to research of the making process based on the metal spinning of helical tubes that will be used as the heat exchangers, and determination of optimal parameters of the process by which to predict and provide making helical tubes without breaking. The character of influence of the main parameters (geometry of the workpiece and tool, workpiece rotation frequency, the number of passes rollers, value backpressure) of metal spinning process on the formation of helical tubes and stress-strain state in tube during its making were determined. The recommendations for the design of technology and equipment for metal spinning forming processes of one- and three-start helical tubes were developed. The developed method and technology for making of helical tubes without mandrels using internal back pressure. Numerical simulation by finite element method was made an estimation of influence of internal back pressure on the stress-strain state in the course of treatment of tubes made of stainless steel AISI 304 and aluminum alloy aluminium-2017. The analytical dependencies for the approximate determination of the stress-strain state, specific stress and roll pressing force indentation in the tube were obtained. The results were quite experimental verification and industrial approbation and allowed to set new schemes of making one- and three-start helical tubes without using mandrel and develop making technology such products which based on the recommendations presented in the thesis.