Design And Optimization Of Forging Process For Aluminum Alloy Pump Housing Of Motor Vehicle Exhaust Aftertreatment System

The aluminum alloy pump housing was an important part in the motor vehicle exhaust emission disposal system,mainly used in the cyclic transport of catalysts.The performance requirements of the aluminum pump housing were high because the aluminum pump housing was often in a harsh working environment with high temperature,high pressure and high corrosion.Since the commonly used cast aluminum pump housing was prone to corrosion and cracks,which affected the stability and safety of the system,it was necessary to improve the overall performance of the aluminum pump housing by forging.In this paper,an aluminum pump housing as the research object,the forging process and die design was studied at first,and then the shape of the billet was improved by the finite element simulation software Deform-3D.After that,the forging quality was improved and the overall cost was reduced by optimizing the forging parameters.At last,the heat treatment process and microstructure of forgings were studied.The main research contents were as follows:(1)Aiming at the structural characteristics and forging difficulties of the aluminum pump housing,the process difficulty and manufacturing cost of the forging were reduced by reasonable forging design.Then,from the perspective of forging quality and cost,a forging scheme for profile billet,precision forging and trimming was developed.After that,the precision forging dies and elliptical section profile billet were designed.At last,the test forging verification was carried out and the obtained forgings had defects such as insufficient filling and flashing cracks,so further research on the forging scheme was required.(2)The design and optimization process of profile billets was established based on Deform-3D finite element software and numerical simulation theory,combined with profile billet practical experience.Then,the profile billets of the elliptical,L-shaped and convex-shaped sections were analyzed separately.After that,the convex-shaped section billet was selected,and the trial-forging result was good except that only the L-shaped boss had insufficient filling problems.At last,the reason and optimization direction of the insufficient filling L-shaped boss were analyzed.(3)In order to solve the problem of forging's insufficient filling L-shaped boss,die cracking and flash waste,the boss end face filling rate,the final forging force rate and the forging material utilization rate were selected as the optimization targets,meanwhile the die preheating temperature,the profile billet length,the initial billet temperature and the flash bridge height were chosen as the optimization variables,to design a CCD test experiment.Then the experimental data was obtained by finite element simulation to construct the second-order response surface model,and the differential evolution algorithm was used for multi-objective optimization to obtain the optimal parameter combination.The optimal parameter combination was verified by simulated forging and trial forging,and the both results had achieved the expected results,which showed that the optimization method had practical significance for the production of aluminum pump housing.(4)Solution heat treatment and aging heat treatment of aluminum pump forgings were studied.The mechanical properties and microstructure of the forgings after heat treatment reached the expected standards,which verified the rationality of the forging process and the heat treatment process.This paper combined forging process design,finite element simulation,response surface model and optimization algorithm to solve the forging problem of aluminum pump housing,and studied the heat treatment process and microstructure of aluminum pump housing,which provided theoretical basis and technical support for the manufacture of aluminum pump housing products.