Study On Cold Extrusion Forming Process For Motor Silent Chain Sprocket

Silent chain transmission has the advantage of steady transmission and low noise. It iswidely applied in the transmission device of automobile and motorcycle engine. Sprocketof silent chain was usually used milling processing. It can not meet the needs of massproduction because the process is complex and the production efficiency is low. Coldextrusion is a near net shape processing forming method. In other words, produce partsclose to the final parts requirements and has the advantages of high production efficiency,less material consumption, good surface quality, high metal mechanical properties andhigher level of automation, especially has its unique superiority in mass production. It hasthe widespread application prospect that the cold extrusion technology applied in themanufacture of silent chain sprocket. The difficulty for cold extrusion on motor silentchain sprocket is that the local metal flow severely and process defects will be brought incold extrusion forming. As a result, the forming quality is difficult to guarantee. Therefore，the study of the process parameters on metal flow law, provides theoretical basis for theformulation of process plan and election of process parameters.This thesis was study the tooth surface crack and collapse of tooth profile angle defectwhich was given in cold extrusion forming of silent chain sprocket. On the basis of fracturecriterion, the study method of damage factor as the criterion of crack was established. Thecold extrusion forming process of silent chain sprocket was numerically simulated byRigid-Plastic finite element analysis software DEFORM-3D and the causes of crackdefects were analyzed. The influence of die-entrance angle on rack defects was obtained bynumerical simulation. Through the establishment of velocity field，the effects tooth profileangle of collapse defects of parameters were determined. The effects law of die-entranceangle on collapse of tooth profile angle defect was obtained by finite element numericalsimulation. On this base, the process plan was optimized. The reasonable forming plan andprocess parameters were proposed.On the basis of the above study, it was worked out the cold extrusion process test ofsilent chain sprocket to verify the feasibility of using the damage factor criterion of toothsurface crack defect.