Research On Forging Process And Forming Quality Control Of Marine Long-shaft Heavy Forging

As the most important components of shipping power installation, marine long-axisheavy forgings’ operation effects have a direct influence on a ship’s hydrodynamiccharacteristics and normal voyage. Large ingot always used as the initial billet for heavyforgings, which is inevitably existing defects externally determined by its metallurgicalprocess, and those defects should be improved and eliminated by applying reasonable forgingprocess so as to obtain the high quality marine long-axis heavy forgings with good dimensionaccuracy and internal quality.The research subject is supported by2010~2012Guangdong Major Research andDevelopment Project (2009A080304004)“Research on forging reduction and waste heatrecovery technology of marine industry heavy forgings and Its application in shippingindustry” and2008~2010Guangzhou city scientific and technological planning project(2008Z1-D221)“Research on key technology of forging for heavy forgings with complexlong axis and Its application in shipping industry”.The forging method and parameters are studied based on DEFORM-3D simulationresults and existing theory in this paper, then the whole process are simulated inDEFORM-3D. The main research contents and conclusions of this paper are summarized asfollows：(1) Multi-step continuous forging been realized in the text mode of DEOFRM-3Dsoftware by writing commands to calls related function module. Then the method and finiteelement model were tested by verification experiment, and they were proved to be correct bycomprising and analyzing of simulation results and experimental results.(2) Flat anvil forge method, FM forge method, and unequal Flat anvil forge method beenstudied, and the numerical simulation results show that when using Flat anvil forge method,the forming efficiency, forging quality and temperature field distribution are better than othermethod, thus flat anvil forge method were choose as forging method in this paper.(3) From the point of view of stress distribution，inner defects compaction and materialdamage, the relative reduction η=20%~25%is ideal for squaring and stretching process.(4) The whole forging process was simulated in DEFORM-3D, and it shows thattemperature distribution can meet the forging requirements. In the first and the second firingforging, two dimensional tensile stresses (stress X, stress Z) are existed in billet cross sectioncenter because of anvil width restriction. After the third forging stretching process, the billetwas in a state of three-direction compressive stress，which is ideal for forming. (5)The billet axis straightness was tracked in the whole process, billet axis prone to bendduring the stretching process of the third heat forging. When using90°-90°inversion method,feeding form rigid end to flange period，Axis bending can be avoided while high forgingefficiency can be assured.（6）Center loose model was established in this paper, and it can be effectively forgingclosed by adopting the preset process. That means the high quality intermediate shaftwithgood dimension accuracy and internal quality can be forged with the preset process.