| Steering knuckle is one of the most important car key parts and a security part. It supports the body weight, transfers steering moment and endures braking moment of front-wheel. The requirement of its mechanical characteristic and contour structure is so strict that it is very hard to produce. It is urgent to solve how to produce it efficiently and economically.In this paper, with the guidance of precision forming complex components, basing on the forming theory of obturated-extrusion, combining the technique of hot extrusion, considering the characteristics of steering knuckle, so the one-step precision obturated lateral-bend extrusion forming method and the two-step forming method are presented. The two-step forming method is composed of precision lateral-bend obturated-extrusion preforging and open die forging. The one-step forming method and extrusion-belt style precision obturated-extrusion preforging of the two-step forming method are studied on three-dimensional thermal coupling FEM analysis by UGII and DEFORMTM. So the metal flow rule and the distributions of strain, stress, velocity and temperature can be obtained, so as to the stroke-load curve. Focusing on the one-step forming method, the influence of main technique parameters to metal flow and extrusion load, and the influence of forming velocity to temperature field are studied. Based on the influences, the main forming parameters are determined. The one-step forming method is also studied on the physical simulation experiment, which verify the correctness of numerical simulation and the feasibility and advancing of obturated-extrusion technology.The new technology which realizes lateral-bend extrusion in once-through stroke, greatly simplifies the production technology of car steering knuckle, reduces the production cost, and makes it possibly produce in china. It also enlarges the obturated-extrusion applying range and provides experience for the precision forming of the similar branch-like parts.
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