Numerical Simulation On Push Bench Process Of CPE

In the production of hot-rolled seamless steel tubes, CPE push bench mill is one of the important methods. CPE push bench mill has the advantages of lower investment, being easy to operate and to maintain equipment and large elongation coefficient.The D/S of the tube produced by this process can reach above 40. So the CPE push bench mill is suitable for producing seamless steel pipes with thin-wall thickness and small/medium diameter. But when producing some certain kind of steels, wall-thickness shrinkage and surface crack often appear. For now, there are still fewer literature researches on the metal deformation behavior of steel tube during the manufacturing process by CPE push bench mill. The production of steel pipe mainly relies on experience and the process is unstable. Therefore, this experiment investigates the process of CPE push bench, thus to provide scientific proof for the improvement of this process.Based on the CPE push bench mill of Jiangsu Changbao Steel Pipe Co., Ltd.'s, and with the aid of commercial finite element software Simufact, the push bench process of CPE is simulated. The 5Cr steel tube with a typical specification of ?110×4.85 mm is used in this process. This paper mainly studies the mandrel force, the precision of the transverse wall thickness and the occurrence tendency of surface crack defects.The main conclusions are as follows:(1) The friction coefficient between workpiece and mandrel has a significant effect on the mandrel axial force during the push bench process; while the friction coefficient between steel tube and roll has little influence on it;(2) The transverse wall thickness of the workpiece along the width direction of groove features an approximate W-shaped distribution. The maximum value is obtained at 30° along groove width; the minimum value is obtained near by the top and the bottom of groove;(3) When the friction coefficient between workpiece and mandrel increases, the transverse wall thickness of the workpiece is increased, but the precision of it is reduced. The friction coefficient between roll and steel tube and the initial temperature of the workpiece have no obvious impact on the precision of the transverse wall thickness;(4) During the push bench process, the stress, equivalent plastic strain and effective strain rate of workpiece's inner layer is very large near by the top and the bottom of groove, it is very easy to produce crack at this point.