Intensification of high-temperature bottom plates forming

Abstract

The issues of high-temperature forming for the production of elliptical steel beaded bottoms, used in vessels and apparatuses with an internal diameter from 300 to 1800 mm, made of carbon, alloy and ply steels, are viewed. There is information that the authors have been studying this forming process of a workblank with no temperature pattern change. There is also data on examples of tests that allow reducing the thickness difference in the bottom plate from the standard 15 % of relative deformations to 12%. It is shown that the use of a variable temperature pattern will make it possible to increase the extraction coefficient by several times and obtain vessels consisting of two body parts. It is noted that the issue of the influence of changes in the hardening curve when heated on the stability of hot-temperature forming has not been viewed in technical publications yet. The possibility of using the QForm program for the analysis of the stress-strain state for high-temperature forming has been studied. The simulation of the heating of the billet in a gas furnace is carried out. As a result of the calculation, a temperature pattern and a distortion of the shape of the workblank were obtained. Comparison with the experiment revealed good convergence of the results in terms of temperatures and qualitative coincidence of the workblank shape. It is noted that QForm simulates the locations of the places of maximum relative deformations quite well, that is coincident with the results of experimental die forming and theoretical solutions for draw-forming of parts with a spherical bottom. Based on the results of the work, recommendations are given for obtaining bottom plates according to the first class of accuracy, when the maximum relative deformations in thickness should not exceed 4,0 %.