Study On End Quality Of Shaft Parts By Cross Wedge Rolling

Cross wedge rolling has received widespread application in practically manufacturing shaftparts with many advantages such as high efficiency and high material utilization. For shaft partsend rolling, concavity produces in the end transversal section after rolling and should be cut.Manufacturing shaft parts, stub bar of10-20mm length on both sides should reserve, which leadsto the material utilization of cross wedge rolling under85%. How to realize less cutting or nocutting and improve the material utilization are the key to promote the development of cross wedgerolling. Therefore, study on end quality of shaft parts by cross wedge rolling has importantpractical significance.Cross wedge rolling shaft parts end rolling are simulated by finite element analysis softwareDEFORM-3D in the paper. The stress and strain of workpiece are obtained and the metal flowingregularities are got in the rolling process. The concavity is analysed by methods of displacement,grid and axial strain. The reasons of concavity are that the metal in surface flows faster than incenter and the axial strain in surface is bigger than in center. With the accumulation of nonuniformaxle strain, the concavity reaches the maximum.According to the production mechanism of concavity, the paper provides two ways toimprove workpiece end quality with setting block wedge and designing blank shape. Based on thedesigning principle of block wedge, the block wedge is put in the rollers closing to workpiece end.The influence mechanism of block wedge on end transversal section quality is analysed in terms ofstress, strain and axial velocity. Block wedges can hinder the surface metal flowing faster. Thenmetal flowing velocity in the center and in the surface tends to be synchronous. The end concavityof workpiece can decrease effectively. The influence regularities of blank shape on axialdisplacement, axial velocity and axial force are analysed. And the influence mechanism of blankshape on end transversal section quality is got. For cross wedge rolling shaft parts end rolling, theconcavity values decrease as the blank shape angles decrease. So the blank shape can effectivelyimprove workpiece end quality. The influence regularities of blank shape on end concavity areverified by experiment. The experiment results are consistent with the simulation results.The research results of paper have important theoretical significance and engineering valuefor improving material utilization and promoting cross wedge rolling.