The Numerical Simulation Of Hot Forging And Die Optimization For Automobile Steering Knuckle

With the high development of the automobile industry, vehicle population has grown steadily, the demand of high precise, complex and complicated shape forgings are becoming more and more big in the auto parts market. Automobile steering knuckle is the key parts of car between front axle and wheel. The requirement of its mechanical characteristics and contour structure is so strict that it is very hard to produce. Hot forging process can improve the micro-structure of the metal billet, physical and mechanical properties of metals, so the steering knuckle with hot die forging production. Furthermore,steering knuckle forging are mostly S4 level according to GB12362 definition, forming is difficult and bring certain difficulty to process design and die design.Steering knuckle in the Toyota IMV pickup as the research object in this paper, the reasonable forming process scheme and die structure were put forward through analyzing the characteristics of the steering knuckle structure and combining with actual production.Finite element modelling of the hot forging process for steering knuckle were performed by using Deform 3D, the velocity field in the process of forging forming were analyzed and the law of metal flow was obtained. The reason of forgings fill difficultly was got by using speed point tracking on steering knuckle long metal ends, namely the flash land resistance of long fork peripheral is too small, cause the metal premature flow to flash,billet supply shortage, lead to the long fork failed to full completely and forming corner collapse. Based on the results of numerical simulation, two resistance wall structure were introduced to improve mold, the results showing that: the established resistance wall can delay the metal flow to flash, promote metal filling the long forks cavity, but unreasonable resistance wall structure easily lead to excessive load rise, the uneven deformation of metal and forming defects.The resistance wall structure design variables of steering knuckle forging die were given in this paper, the sort of the importance of resistance wall structural parameters onthe filling property, the forming load and the die wear were analyzed by using fractional factorial design. Four key parameters were screened: the bridge width b, resistance wall slope A, resistance wall clearance n, resistance wall width L. The generalized regression(GR) artificial neural network was developed to study the four relationship between four key resistance wall parameters and the steering knuckle forming process, then the quantitative effects of resistance wall parameters on long forks filling, forming load and die wear were analyzed. And the parameters of the resistance wall were optimized, namely,bridge section width b is 14 mm, resistance wall slope A is 0 deg, the resistance wall clearance n is 3 mm and resistance wall width L is 40 mm. Finally the optimized steering knuckle die were numerically simulated and actual production verification.