Numerical Simulation For Warm Precise Forming Of Cam

The auto industry plays an very important role not only in developed countries but also in China because of extensive relationships with other industries and high market requires ,high active effects to scale, and always bringing energy to other industries. With the development of motorization in China, low energy cost, environmental friendly, and safety in auto industry gradually became the keys. And all above have very close relation with the engine.Engine is the heart of an auto and camshaft directly impacts the whole performance of a car as it is one of five most important parts of the engine. There for now the requirement of the camshaft making level is gradually getting higher and higher. Traditional camshaft making process does not meet the development of the auto industry now. The fabricated process which is found about early twenty years ago which can make design, option, and performance together has changed the tradition and become the broken point in the history of camshaft making.Making process is the most important factor that affects the cost of making camshaft. It will surely lose advantage of assembled camshaft that if chose the traditional ways. Near-net-precision forming technology can significantly turn cost down and make process simple, cut time consumption, optimize cam profile,increase productivity and realize the feasibility of the assembly. There for there is very important significance of researching the Near-net-precision forming technology.Five programs of pre-forging cavity are designed in the paper.Three-dimensional model was established by using CATIA and warm forging process of the cam was simulated by using three-dimensional finite element numerical simulation of coupled thermo-mechanical simulation form. By numerical simulation velocity field, stress field, strain field, temperature field, as well as the process of forming the load - stroke curves of forgings was got in every moment during simulation. And deformation discipline of the warm precise forging process of cam was achieved by analysis and comparing those mentioned above. By the end of the paper,a sufficient basis of determining program of pre-end forging of warm precise forging process of cam was provided.Based on the numerical simulation, this paper analysis the main process parameters of warm precise forging process of cam and main conclusions were made as follows:In the process of warm precise forging process of cam, with other simulation conditions fixed:1. Mechanical fields, metal mobility, effect of cavity filling and load which based on different ratio of height to diameter of billet are different. Reducing the ratio of height to diameter appropriately can lower temperature difference and can also uniform the distribution of stress and strain, reduce work-hardening, make the effect of cavity filling better and reduce the forming load. As the result the wear condition will better and die life will be prolonged.2. It can increase metal plasticity, reduce the deformation resistance, uniform forging deformation, reduce equivalent stress, improve the formability and prolong die life by increase the forming temperature appropriately. And it can make corners more plump, get good cam shape forgings by reducing the metal flow speed. Higher forming temperature can increase plasticity of the blank, reduce the deformation resistance, so it reduces the forming load of cam, improves die stress environment and prolongs the die life.3. With the increase of deforming rate, strain rate, deformation resistance and inner strain of the metal are increasing. And at the same time, large number of heat which is produced by severe plastic deformation is not able to lose to surrounding medium. It brings temperature increase of forge, temperature difference of inside and outer forge, and uneven of stress and strain distribution. And besides, because of heat which is produced by severe plastic deformation is not able to lose to surrounding medium, temperature of forge will be increased, deformation resistance will be reduced. So deformation rate have little affect to load. With the increase of deforming rate, flow rate of material is increasing significantly, and filling small head of cam will be difficult. So it will be better reducing deformation rate.4. With the increase of friction factor, friction between the mold and the blank increases, and it will be easy to form the surface work-hardening and affect forming properties. And at the same time ,the maximum temperature of the forge is increasing, the minimum temperature of it is reducing. And besides, forming load is increasing. There for, we can reduce the demands on the forming equipment, energy consumption, die wear and fail and prolong die life by using reasonable lubricants and method of lubrication to reducing the forming load. All of those mentioned above have significant effect to precision forging process.