Evaluation of deformations of thin-walled pipes during cold bending with rolling

Abstract

The results of experimental evaluation of deformations of thin-walled pipes during their cold bending with rolling are discussed in this paper. The review of application of curvilinear elements of pipelines is considered. The methodology of the experiment is presented. Special equipment for cold bending pipes with rolling was used for experiments. The grid method was used as the basis for the strain estimation method. The measurements were carried out with an electronic caliper and a microscope of the MIM-340 model with an accuracy of 0.01 mm. The evaluation of deformations for various materials and pipe diameters is given in detail: steel Сk10, steel X10CrNiTi18-9 and brass 2.0280. The values of elongation and reduction of the length of the walls of the pipe involved in the beating were determined. For a general assessment of the deformations and residual stresses, summary comparative graphs of changes in the geometric shapes of pipe samples after bending with rolling were constructed by the method of studying the absolute elongations of pipe walls during bending with rolling. It is established that the degree of deformation of pipes obeys a certain regularity. Of a particular interest is the bending of pipes made of corrosion-resistant steel. In this regard, similar experiments were carried out on bending of the pipes from corrosionresistant steel X10CrNiTi18-9. The thickness of the pipe walls and its length are calculated for three different variants of the pipe material, and their average range is given. As a result of the studies, dependencies were obtained that can be used to determine the nature of elongation and reduce the length of the pipe walls at various places of curved pipes, to determine the degree and nature of deformation in the longitudinal and cross sections of the pipe walls during bending with rolling and, as a result, to calculate these deformations and thinning of the pipe walls, which is an important operational characteristic.