ЕКСПЕРИМЕНТАЛЬНЕ ДОСЛІДЖЕННЯ ВПЛИВУ ПОЗДОВЖНЬОГО РОЗТЯГУ НА ПРУЖИНЕННЯ СМУГИ ПРИ ПОПЕРЕЧНОМУ ЗГИНІ

<jats:p>The subject of the study is the process of transverse bending of a thin-walled strip under the simultaneous action of longitudinal tension and the regularity of the influence of longitudinal stresses on the magnitude of springback after unloading. The study is a continuation of theoretical works devoted to profiling with longitudinal tension and solving the problem of rigid-plastic bending of a strip. The purpose of the work is to experimentally verify the theoretical provisions regarding the influence of longitudinal tension on the springback of a strip during transverse bending and to establish the dependence between the level of longitudinal stresses and the parameters of elastic recovery. The task is to develop a methodology for experimental research, create a special test fixture, determine the mechanical characteristics of the materials of the test specimens, conduct tests at different levels of longitudinal stresses and establish the dependence of the residual deflection and relative springback on the magnitude of longitudinal tension. Methods. Experimental methods were used to study the process of plastic deformation during transverse bending with longitudinal tension. The test was carried out on a specially designed device installed in a universal testing machine. The study was performed on flat samples of heat-resistant corrosion-resistant alloys Kh18N9T with a thickness of 0.18 mm and KhN78T with a thickness of 0.30 mm. The results were processed using methods of mathematical statistics and measurement error analysis. Results. A methodology for experimental research and a special device for testing at a given level of longitudinal stresses were developed. The dependences of residual deflection and relative springback on the magnitude of longitudinal stresses were obtained. It was found that with increasing longitudinal stresses, the residual deflection increases, and the springback after unloading decreases, which confirms the effectiveness of using longitudinal tension to increase the accuracy of shaping thin-walled profiles. Conclusions. The proposed test method and experimental equipment provide reliable determination of springback parameters and can be used to study the processes of profiling thin-walled products. Scientific novelty. The theoretically established regularities of the influence of longitudinal tension on the magnitude of the springback of the strip during transverse bending were experimentally confirmed and the quantitative dependences of the residual deflection and relative springback on the level of longitudinal stresses were obtained, in particular for heat-resistant corrosion-resistant alloys.</jats:p>