Study On The Half-closed Forging Of The 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. While the working procedure is complex and the higher waster rate is very high. The most important thing is how to predigest the billet and increase the material using rate and the precision of the forging parts. It is urgent need to solve the problem that how it can be produced efficiently and economically.In this paper, based on the technique of precision forming of complex components, the mould invalidation forms and the elements which affect the mould's life are analyzed according to the extrusion and forging theory. The reason of the filling discontent, local distortion and collapse are researched, and a new forming method, i.e. half-closed forging (pre-forming)--forging--trimming, is presented. It also analyses the important parameters such as the figure and dimension of the billet, the shape change of the forging part, the distributing of the equivalent strain. And the limitation in the forming process has been solved by pre-forming design.The process of extrusion precision forming (pre-forming) and the forging process are studied by three-dimensional thermal coupling FEM analysis with the aid of UG and DEFORM, so the metal flow rule and the fields of strain, stress, velocity and temperature can be obtained. The influence of the main technical parameters on the metal flow and extrusion load, and the influence of the forming velocity on temperature field are studied too. Based on these researches the main forming processing parameters are determined. The successful experience is summarized by contrasting the simulation result to the experiment, which confirms the correctness of numerical simulation and the feasibility of this technology.The new technology realizes forming in two cavities of one mould, which 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. According to this research, the life of the forging mould, the theory of the FEM analysis, the numerical simulation technology and the CAD technology have been combined, which helps to shorten the production exploring cycle, prolong the life of the mould and reduce the cost. The research provides theory and practice direction to choose the parameters of the steering knuckle die, which proves that the parameters are reasonable and scientific by production and can be used to direct the production.