Simulation And Experiment Study Of Cold Rolling Spline Dynamic Constitutive Relation

Involute spline is a kind of common transmission part, and cold rolling process is a way of splinterless processing. By this method, workpiece is impacted and deformed into spline tooth plastically by a pair of rollers, which have the same shapes as the tooth profile and rotate around axes when processing. Compared with traditional processing methods, cold rolling process has high production efficiency, low steel consumption, and can improve the surface hardness and quality significantly; therefore, the carrying capacity and service life can be highly prolonged. Though the forming mechanism, forming force, machine tool design and roller shape modification about the plastic forming process have been studied by many researchers, few studies are developed from the basis of dynamic performances of workpiece materials, and studies of stress and strain variation under different rolling velocities are also very rare. However, these factors all affect the processing efficiency, the roller service life.In order to fully use the green manufacturing technology, the present thesis investigates accurate dynamic constitutive model of the workpiece material, and the deformation law under vary rolling velocities by means of dynamic impact tests and explicit finite element analysis software. On the basis of the present research, suitable rolling velocity is determined, and experimental study are developed on the spline which produced by experimental process.By means of dynamic impact experiment, explicit finite element software and based on the plastic mechanics, the present thesis determines the dynamic constitutive model of material 40Cr, researches its dynamic performance by SHPB system, and get the parameters of the material, and then simulates the cold rolling processed under different rolling speed by using the FEM software LS-DYNA. The thesis discusses the relation of forming conditions and rolling speeds by analyses the stress and strain regulations under different velocity, and determines suitable cold rolling velocity. By experimental manufacturing and research, the tooth fiber structure, residual stress of the tooth bottom, surface layer hardness and surface roughness is observed and measured; the thesis analyzes the mechanical properties of the spline. The results reveal the reason of high internal quality of the cold rolling spline under suitable velocity, and the researching results provide important resultant value for the process design and practical production of cold rolling involute spline.