Two-roll Straightening Process And Key Technologies

With the development of economic and improvement of science and technology, the quality of steel products becomes more and more important. Because of some kinds of reasons, in the process of heating, rolling, cooling, heat treatment and transportation, bar may have some defaults such as bend of multi-directions. These defaults must be eliminated by straightened in the later process, so that the flat product can be obtained. The two-rollers straightening has the unique advantage in the Straightening process, and with the high precision and good quality. Its straightening ability is determined by the curvature's variation of the straightening roll. However, the research on the roll shape has been greatly dropping behind the manufacture demands, and presently many rolls are designed on the basis of linear bars contacting with the whole span of the roll, or dealt with the data from manufacture locales. These rolls have many disadvantages and bad applicability, which do harm to manufacture and production efficiency.This paper bases on elastic-plastic bending theory, consults with previous designing experiences, designs the new unilateral tri-curvature reverse-bending roll and the bidirectional tri-curvature reverse-bending roll. When designing, the first step is to get the curvature of each section of the straightening roll on the basis of straightening characteristics of bars and tubes; the second step is to establish dimensional model, accomplish vectors'analysis, and get the accurate formula of the roll shape. Through the roller shape formula and using the Matlab, calculates every segment of roller shape curve, develops straightening rollers range fromΦ5mm toΦ200mm.Built 3D elastic-plastic fem model of the straightening process, simulated the whole process of Two-roll straightening dynamically by LS-DYNA, to test and evaluate the rationality of the design of roller shape .The characteristics of stress and strain distribution during the two-roll straightening are obtained by the finite element analysis; analyzed the residual stress's distribution and the influence of straightening quality on different straightening parameters. According to the bar of the different materials and different diameter experimented, the straightening accuracy and the surface quality can meet the practical requirements and verifies the rationality of the design of roller shape. At the same time, programmed a roller shape design system of two roll straighter by Visual Basic software, the engineering design personnel can use the system convenient.