Technological Analysis And Numerical Simulation For Precision Forming Of Cam

Assembled camshaft,which combines the design of camshaft,materials selection andthe optimization performance together,has offered a range of remarkable advantages in costreduction,weight saving,excellent performance.As a novel technology,assembled camshafthas obvious advantages,it is the main developing object of camshaft manufacture.The precision forming technology of cam, which is the most important factor thataffects the production efficiency and manufacturing cost of assembled camshaft,is the coreof technology of assembled camshaft. Near or net shape forming technology of cam ismainly include precision forging of steel,precison casting of alloy cast iron,powdersintering (forging) of powder material.The cam of precision forging with precision and highquality,have significant economic advantages.For example,it have good wear resistance andimpact resistance,and also can remarkablely reduce costs,save energy.Therefore,the researchand investigate for precision forging technology of cam have important siganificance.By means of numerical simulation,this dissertation aims to find the best cam precisionforming method and dies design in order to provide theoretical guidance and valuablereference for the actual cam precision forging production. The major research is summarizedas follows:1、This paper take typical cam sample(Ford V348camshaft) as example,and analyzeits part drawing.Combination of the GCr15materials performance,the thesis analyzed thetechnical difficulties(include recess design and pre-forging cavity design),designed moldingprocess for three forming methods (cold, warm, hot precision forging) and gave two sets ofthe mold cavity design at each forming method.2、 By using DEFORM to conduct three-dimensional finite element numericalsimulation for six programs of cam precision forging in this paper. The velocity field, stressfield, strain field, temperature field,and the process of forming load-stroke curves offorgings were got in every moment through numerical simulation, and then these sixprograms were analyzed by comparing to each other,finally,deformation discipline of theprecise forging process of cam was acheived.Warm precision forming of cam is the bestforming method by comparing the simulation results. 3、Cavity design of pre-forging has an important influence on precision forging ofcam.On the basis of end-forging mold cavity of program F, we optimize its pre-forging diecavity and determine the optimal design project of G from the three different pre-forgingschemes by numerical simulation analysis in this paper.compared with project F, Formingforce reduce30%,stress reduce11%,temperature of forgings decrease17℃for Project G.4、Based on the numerical simulation，this paper analyse the main process parameters ofwarm precise process of cam,and with other simulation conditions fixed during warmprecision forging process of cam，the main conclusions were made as follows：①With the increase of the friction factor, the load force and the temperature of billetincrease.The value of stress of the billet and mold contact area is large, which has seriouslyimpact on the mold and influences the cavity size.It is likely to cause abrasion and elasticdeformation of mold, these results are not conducive to the filling of the cavity corner andalso influences the effect of forgings forming. Therefore, reducing the friction factor hasgreat significance for the precision forging process.②The forming speed which is too high or too low, is not good for warm precision forming ofcam. When taking the middle value of forming speed20mm/s，the stress，the load force andtemperature difference between the billet of the end-forging are minimum.At the sametime，the metal flow is relatively stable and easy to fill the cavity corner, forming effect offorgings is best (little burr). Accordingly, the speed of20is best for warmprecision forming of cam.③Appropriately increased of forming temperature can reduce the deformation resistance, theforming load and the stress of the forgings.It also can improve its formability,extend the lifeof the die,increase metal plasticity which is conducive to fill the cavity corner fully.So thegood forming cam is fabricated.However, if the temperature is too high, forgings oxidizeseriously and the volume of mold elastic deformation becomes large.So the damage isserious in high temperature.The most suitable temperature is850℃which was choosed inthis forming of cam.④In the process of warm precision forging of cam,preheating of mold (300℃) cansignificantly reduce the forming force.The stress and temperature of billet are significantlyreduced when pre-forging and end-forging ended.On the other hand, the flow velocity ofmetal in the corner is small.The flow is smooth and the effect of filling is optimal,whichreduces the impact to the equipment and improves the life of die.