Study On Technological Parameters Of Stretch Reducing Of Seamless Steel Tube

The competitive essence of steel tube market is the quality and the cost.As the last deformation process of the hot rolling seamless steel tube,the stretch reducing process is important to the geometric size of the end tube.During the rolling of the thick-walled tube,the inner hexagonal defects are prone to occur,resulting in a decrease in the yield and a reduction in the competitiveness of the enterprise.With the continuous maturity of numerical simulation technology and the continuous improvement in computing speed,optimization of the end tube quality becomes to be realistic by using the finite element method to simulate the stretch reduction,and to study the effect of metal flow law and the impact of the process parameters on the internal hexagonal defects.Based on the numerous collections of domestic and foreign research findings on stretch reducing,the following work was carried out:According to the theory of stretch reduction,the software of stretch reduction is programmed by using Visual Basic.It can calculate parameters of the roll pass shape and the roll speed rapidly.By using the software of Marc,25-frame stretch reducing process was simulated.The variation of thickness in stretch reducing rolling process was studied in which the initial tube billet of Φ119mm ? 9.75 mm was rolled to the final dimension of Φ51mm ? 10 mm.Several control groups were created to study the impact of roll pass shape、wall thickness coefficient and roll speed on transverse wall thickness precious.Simulation results showed: compared with the positive spread roll pass,the negative spread roll pass can effectively suppress the generation of uneven thickness.The uneven thickness of the wall occurs in the thickening stage of the stretch reduction.The uniformity of the wall thickness can be further improved by adjusting the roll speed to reduce the thickness increase during the wall thickness thickening stage.The uniformity of the wall thickness can be improved by selecting properly coefficient of the wall thickness.Through optimizing the roll pass shape to reduce the wall thickness reduction at thebottom and the gap of roll in the wall reduction stage to offset the accumulation of wall thickness in the middle zone of the wall thickening stage,it can effectively suppress the generation of wall thickness unevenness.