Simulation Research On Roll-forging Process For Thick-walled Hollow Patr

Roll-forging is a way to produce the forging piece by means of rollers, and it presents a seriesof advantages, such as light weight of equipment, low driving power, high production efficiencyand stable size of forging piece. With the increasing development of FEM software, traditionalmethod has gradually been replaced. Making use of FEM to simulate roll-forging forthick-walled hollow part, it is very beneficial for optimizing the rolling die design, controllingthe quality of hollow part, revealing metal flow law during roll-forging process, making up forthe theory blank of roll-forging for hollow part and improving the roll-forging technologyapplied in hollow part.Because roll-forging theory of thick-walled hollow part is blank and existing roll-forgingtheory of solid part just plays a role in guiding rolling die design，the gap between designed diesand actual ones is bigger. It not only extends the on-site commissioning time, but also inevitablywastes a lot of manpower and resources. By means of DEFORM-3D to simulate the wholeroll-forging process for thick-walled hollow piece including metal flow law of hollow part、equivalent strain field distribution of typical sections、temperature field distribution、situation ofwall thickening、 influence law of gap、friction coefficient μ、temperature and reduction onroll-forging for hollow part，and it can save cost, reduce trial cycle and improve efficiency.Based on existing roll-forging process, not only the size of original tube blank and roll-forgingsteps are determined, but also the grooves are selected and rolling passes are designed.Roll-forging part and fan-shaped dies are modeled by CATIA, roll-forging FEM for thick-walledhollow part is set up, and roll-forging for thick-walled hollow part is finished through two stepsand one step for reshaping.At the same time, rolling dies are modified according to thesimulation results. This paper systematically analyzed and studied positioning, contact, bite,constrained conditions and pass increased to shape during the thick-walled hollow roll-forgingprocess simulation, and all the results are of great value to establish roll-forging theory of the hollow part.Compared with simulation results of roll-forging for solid pieces, influence law of wallthickness on elongation and width is revealed, and effect of friction coefficient μ on roll-forgingfor solid part and hollow part is discussed. According to experimental product of hollow part,geometric sizes、forward slips、wall thickening conditions、defect types and mechanisms ofemergence of the defects of two products are coincident by contrast, accuracy and reliability ofFEM establishment are proved. In the paper, improving methods of defects are presented, androll-forging process for hollow part is again simulated after rolling dies are modified. Thesimulation results indicate after increasing the roll-forging step, ellipse degree of circular sectionhas disappeared, efficiently improved quality of the forging piece, and provided a reference forguiding the actual roll-forging for thick-walled hollow part.