Analysis Of Wall Thickness Accuracy Of Seamless Steel Tube Push Bench Process For CPE Mill

CPE push bench mill is one of the most important mills to produce hot-rolled seamless steel tubes.It has the advantages of low investment,low operation cost,good product quality and high production efficiency.However,due to the lack of research on the deformation behavior of push bench mill,it mainly relies on experience production,especially in the production of medium and small diameter thin-walled and middle-walled steel tubes with high-grade(for example 13Cr and T91 etal),the uneven wall thickness of steel tube is serious,which seriously affects product quality and enterprise economic benefits.Therefore,it is undoubtedly of great theoretical and practical significance to systematically study the influence of different process and tool parameters on the accuracy of horizontal and longitudinal wall thickness of steel tube in push bench process,and to provide scientific basis for the optimization of process parameters and pass in actual production.Aiming at the serious problem of uneven wall thickness in actual production of seamless T 22 steel tube by 114 mm CPE push bench mill,the force and energy parameters,stress/strain field of rolled parts,pass filling of rolled parts in each stand,transverse wall thickness and longitudinal wall thickness distribution of barren push bench technology and tools were analyzed systematically by means of commercial finite element analysis software Simufact.The effects of parameters such as mandrel speed,mandrel lubrication state,hollow shell temperature and pass structure parameters on the accuracy of horizontal and longitudinal wall thickness during push bench are systematically studied.The main conclusions of this paper are as follows:(1)During push bench process,the horizontal wall thickness distribution curve of workpiece approximates to“?”,which is the smallest at the top of the hole and the roll gap,and the largest at the side wall of the pass;the longitudinal wall thickness distribution of workpiece gradually decreases from the tail of workpiece to the head,and the wall thickness of the head area of workpiece is the thinnest.(2)The main factors which cause the serious non-uniformity of transverse wall thickness of workpiece are the serious non-uniform deformation of metal in the stand with large wall reduction,the large axial tension stress at the roll gap and the pulling force of the fast speed mandrel to the workpiece forward.(3)Considering the production efficiency,energy consumption,tool wear and uniformity of wall thickness,the mandrel speed Vmax=2.7 m/s should be selected in actual production.(4)With the increase of friction coefficient of mandrel,the average wall thickness of workpiece increases.When friction coefficient of mandrel f=0.08,the longitudinal wall thickness of workpiece has a better non-uniformity.(5)When the initial temperature of hollow shell increases from 1010~?C to 1050~?C,the transverse wall thickness non-uniformity of workpiece decreases from 9.64%to 7.69%.The change of hollow shell temperature has little effect on the uneven longitudinal wall thickness of workpiece.(6)The bigger the wall reduction is,the thinner the roll gap is,the bigger the additional strain is,the more the transverse flow of metal is intensified,the non-uniformity of metal flow at the opening of pass increases,and the non-uniformity of transverse wall thickness of workpiece increases.