Evaluation of stress–strain state in the combined process of straightening and strengthening of non-rigid cylindrical parts

The article examines the stress-strain state of flexible cylindrical parts during the combined process of straightening and strengthening with flat wedge plates. The relevance of the work is determined by the need to improve the geometric accuracy and operational reliability of long, low-rigid shafts subjected to significant deformations during manufacturing and heat treatment. The authors developed a new method for straightening and strengthening flexible cylindrical parts such as shafts and axles in a single technological operation. It is intended primarily for machining parts made of ductile metals and alloys. The objective of the study was to determine the permissible geometric values ​​of curved cylindrical parts and rational technological parameters for the straightening and strengthening process with flat wedge plates. A theoretical model was developed during the study, which made it possible to determine the critical conditions for gripping and stable rotation of a cylindrical billet between the working surfaces of flat wedge plates. Based on the theoretical calculation, the permissible value of the billet initial deflection was determined, which should not exceed 4 mm over a length of 200 mm. To verify the theoretical data, computer simulations were conducted using the ANSYS software package. Using the finite element method, the process’s stable boundaries were clarified. The simulation results revealed that, to ensure the straightness of the billet axis without damaging the surface, the initial deflection should not exceed 3.5 mm over a length of 200 mm. An assessment of the distribution of residual stresses and plastic deformations revealed that the optimal relative reduction ratio is within the range of 1.3 – 1.5 %. The obtained results can be used in development of effective technologies for machining flexible cylindrical parts, contributing to improved performance and manufacturing accuracy. 

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