Multi-objective Optimization Of Forging Process Of Alternator Pole Using Response Surface Methodology

With the rapid growth of auto industry,auto parts with complicated shape and high precision are highly demanded.In order to reduce production cost and enhance productivity at the same time,higher requirement of forging forming precision is put forward,especially for forgings that are difficult to machining.Alternator pole is one of the key components of automobile generator.The research on forging forming process of alternator pole,aiming to improve forming accuracy and reduce the metal losses in form of flash and excessive machining allowances,has carried out for a long time in engineering practice.The shape of alternator pole is very complex,there is a perforated boss in the middle and six uniform sharp pole claws in the peripheral.Only a few parts need a little machining,such as the middle boss and the convex plate plane.Therefore,the forging forming accuracy should be higher than general components.There are serious defects occurring in traditional casting forming process,such as loose,porosity and segregation,which will lead to reducing of the performance of poles.Hence,many scholars have studied the forging forming technology of alternator poles.In the forging method,the alternator poles are usually produced by varying cold,warm or hot forging processes.Aiming to reduce the defects of forging process of automobile alternator pole,such as unfilled,excessive forming load and peak value of local stress,a series of experiments were carried out to obtain an optimal process parameters combination.In the proposed response surface optimal models,unfilled ratio,forming load and peak value of local stress are functions of blank diameter,forging temperature,extruding speed and friction condition.The central composite experimental design(CCD)with four factors and five levels was taken,and then,the second order response surface models were set up.The analysis of multi-objective optimization shows that they are reliable and accurate to predict the forging defects.With the present information of numerical models,a forging case of alternator pole is presented,the result indicates that the precision of proposed models is high enough to meet the engineering requirements.The application of the optimal scheme conforms to the requirements of the production,the precision of the forgings of production reaches ±0.5 mm;material utilization is improved by 10% through reducing the subsequent machining allowance;meanwhile,die life is increased to 2200 times,which is 500 times longer than the traditional method.The application of the optimized parameters scheme leads to lower forging load,smaller peak value of local stress,longer die life and higher production efficiency,meanwhile,the unfilled ratio is greatly reduced i.e.the material losses is decreased and the forming quality is ensured.