Hot-rolled Thick-walled Tube Tension Reducing Process Parameters

Seamless steel tube is widely used in the national economy, and it is an important economic steel. The internal hexagonal defect is apt to occur during hot rolling thick tube, which is a worldwide problem. How to control the internal hexagonal is one of the problems, which have been looking for all the time in seamless steel pipe manufacturing. Aimed at the internal hexagonal of hot rolling thick tube, using nonlinear finite element theory, focused on roller pass and processs design, a series of work was launchedFirstly, the modern theory of seamless steel tube rolling technology should be deeply understood, a new distribution scheme of reducing rates was brought forward, and was adapted to the fact pass design.Secondly, using MATLAB software to generate a file which contained the geometric model keypoint of stretch reducing mill. by APDL parameteric language, a three-dimensional elastic viscoplastic thermo-mechanical coupled finite element model of stretch reducing mill was eventually established. A parametric program was developed.Thirdly, during the stretch reducing process, its temperature, velocity, stress and strain field was analysed by the program. The results showed: the larger the speed difference was, the uniformer the thickness of finished tube was, the smaller P value was, and the better the shape of hole was; as the same stretch reducing mill, different thick tube was produced with the same diameter by adjusting the speed difference; under the same production technique, four initial tube with different shape of the simulation results were compared, and if was found that the shape of initial tube had great effect on the thickness of finished tube, and they geneticed the shape characteristics of initial tube; the temperature distribution in cross section had effect on the thickness of finished tube. the rules of metal flow were revealed, and it guided the pass design and rolling process decision.Fourthly, In allusion to meeting the demand of putting forward a requirement that the initial tube billet ofΦ95×10mm was rolled to the size ofΦ48.3×10mm finished tube, the pass parameters with 22 stads and the process parameters were designed, and thet were tested during industrial trial. The P values of the four finished tube after rolling were all less than 0.037. The experiment was successful. It verificated the feasibility and reliability of the finite element simulation.The above findings, conclusions, pass and process parameters have been successfully applied to large industrial batch production. It indicated that the design of pass parameters and process parameters possessed scientific, reliability and feasibility. The technique parameters are used in batch production of tube, the quality of the product was stable, and achieves good economic benefits.