Optimizing Design And Debugging Of Precision Roll Forging Process On A Coupler Yoke By Numerical Simulation Method

13B type coupler yoke can be weigh about127KG, which is difficult to be formedowing to its complex geometry. The coupler yoke material is subjected to dramaticchange, the original is plain low carbon steel, then Bgrade steel and C grade steel, andnow it develop to E grade steel. Therefore the comprehensive mechanical performancecan be improved, the yield limit and impact property significantly enhanced, which ismore accord with contemporary requirements of railway wagon heavy load and speedincrease. The development of coupler yoke has gone through two stages. First iscasting stage;Second is forging stage, the billet is usually formed in open dieforging,die forging, and then bended in bending die before weld for connecting platesto the two ends because of its complicated shape.This process need two times heating.Now it developed to be a most difficult forming process, which is four-passesprecisionroll forging, and then twotimes die forging, at last lap welding on the two ends afterbending the center part. Based on the advantages of roll forging, the study of coupleryoke roll forging is the policy adaptation of saving energy resources and improvingeconomic performance.Precision rolling forging is primarily used for long shaft type forgings, of whichthe process of front axle, connecting rod is relatively mature. In domestic, the rollingforging process is developing in recent years, and urgently need to be improve. In thepaper, four-passes roll forging production trail has been followed-up investigation.According to the defects appeared in the forming process, such as the die cavity wasmismatching with billet, roll forging instability, the forging with big flash, anterior wallslipping in the third pass. The main content in this paper as following:①The coupler yoke four-passes roll forging DEFORM numerical simulation hasbeen done. Various parameters were properly set in pretreatment, the result in posttreatment, contrast by trail production, which certify the accuracy of the simulation. Todetermine the feasibility use of the production equipment and study on the causes ofdefects, the forging geometry, load, temperature field and the equivalent strain field informing process have been analyzed.②According to the defects of unmatched, flash appeared in the second pass, theflash billet was keeping on extending outward in the third and fourth pass. Theinfluence of manipulator bite distance was analyzed. The primary manipulator bite distance of four-pass is80mm,which changed to be50mm in the first pass,100mm inthe second pass,100mm in the third pass, and95mm in the fourth pass. It solved theabove problems.③Three factors，which is the front wall angle, friction coefficient, and the originalbillet temperaturethat influenced the front wall forming was analyzed according to thebasic theory of the front wall forming. Three factors and three levels of orthogonalexperiment has been used in this chapter. Its vivacity was took to achieve the optimalvalue,as well as the combination, which affect the anterior wall forming. It proved theoptimal combination of these factors, which namely the former front angle of the frontwall is65°, the friction factor is0.7, and the initial billet temperature is1180°C.Practice debugging verified its rationality, and it solved the defect of the third passslipping phenomenon.④The lengthcontrol problem of coupler yoke roll forgings was studied firstly bythe method RSM (Response Surface Method) combined and FEM (Finite ElementMethod).First of all, a second order analysis model is established, in order toresearchroller clearance, friction factor, roller speed and billet temperature, which canresponse the significant and the influence rule of rolling forgings and the maximumtorque.Secondly, the roll forging was simulated with optimized process parameters, theprinciple of debugging the length of roll forgings was firstly presented, the roll forgingdies were redesigned using the principle and point anti-tracking technology, and thelengths of designed, simulated and produced roll forgings and the power dissipationand distribution in one roll process were analyzed. The contrastive results of optimizedsimulation and products indicate that using RSM and FEM can accurately andeffectively grasp the technology of controlling the length of precision roll forgings.Through the study of this issue, the quality of13B type coupler yoke has beengreatly improved, which made the technology of coupler yoke forming is more mature.