Study On New Technology Of CAR Steering Knuckle

Steering knuckle is one of the most important car key parts and a safety part. It supports the body weight, transfers steering moment and endures braking moment of front-wheel. The requirement of its mechanical characteristics and contour structure is so strict that it is very hard to produce. It is urgent need to solve the problem that how it can be produced efficiently and economically. In this paper, with technique of precision forming of complex components, based on the forming theory of combined extrusion and closed-die forging, and taking into account the characteristics of steering knuckle, the new forming method, i.e. combined extrusion precision forming(pre-forming)→closed-die forging (finish-forging)→punching hole and trimming, is presented. The process of combined extrusion forming and closed-die forging is studied by three-dimensional thermal coupling FEM analysis with the aid of UG and DEFORMTM . So the metal flow rule and the fields of strain, stress, velocity and temperature can be obtained, as well as the stroke-load curve. The influence of main technical parameters on metal flow and extrusion load, and the influence of forming velocity on temperature field are studied. Based on the influences, the main forming processing parameters are determined. The method is also studied by conducting the physical simulation experiment, which verify the correctness of numerical simulation and the feasibility of this technology. The new technology which realizes forming in two steps, greatly simplifies the manufacturing of car steering knuckle, reduces the production cost, and makes it possible to produce it in China. It also provides references for the forming of the similar branch-like parts.