Analysis Of Forming Defects And The Mold Design Of Shaft Part With Cross Wedge Rolling Process

The cross wedge rolling(CWR) process is a process forming a cylindrical billet orpart into stepped axial part by means of two molds with wedge groove that are fixed oncross-rolling mills, which rotate in the same direction and drive the billet rotation. Thedeformation is mainly radial compression and axial extension. The CWR technologybelong to one of the rotating rolling technology. The CWR has great advantages of3-7times higher production efficiency,20%-40%higher stock utilization,30%lower costof production, etc., which compared with traditional forming process such as cutting,forging, etc.. Now, the CWR is used widely in the forming process of shaft partsproduction in vehicles, motorbikes, combustion engines which has been one importantpart of modern advanced manufacturing technologies.According to the characters of the CWR shaft parts forming process, the specificcase, connecting rod blanking process, has been selected, the reliable DEFORM3Dfinite element mold was established based on the substantial documents domestic andabroad. The entire process was simulated analysed, the general understanding of theCWR process was acquired via the analysis and discussion in the different situationunder mold loads, velocity state, stress and strain states, temperature, etc..As the complex of mold structure and great deformation of billet in CWR process,how to keep the stable and sustainable deformation has been the essential and difficultpoints to ensure the forming quality in the forming process. To the mold itself, the basictechnological parameters such as stretching angleβ, forming angleαand reduction ofareaφare create obvious influence to the forming effect. Consequently, the formingprocess was simulated based on the initial mold, the influence rules of three primeparameters to the forming quality of billet was analysed through different aspects ofmovement, mechanics, etc.. The mold structure and parameters were designed andoptimized through substantial simulation.Defects like holes in the central position, twist, necking, stocking and spiral stepconcave lines, etc. are the common problems of CWR blanking process, the appearanceof which affect the outlook and internal quality of billet seriously even result in scrapdirectly, and the mass automatic production of CWR process in the meantime. Therefore,it will be theoretical and practical meaning the research on analysis of CWR formingprocess and the defect formation mechanism. In this thesis, the defects of twist， stocking and necking were mainly analysed carefully, the defect position wasemphasized on, the reason was stated through material flow and mold structure. Thedefects were avoided effectively after adopted the optimized mold structure. After then,the ideal result was acquired via practical experiment.The research of this topic not only strengthen the acknowledge of CWR molddesign and solve the practical problems in production, but also save lots of cost ofenterprise. In the meantime, it is also a guidance to other shaft parts forming.