A Trunnion Of Hammer Forging On Fracture And Crack Propagation Research

Trunnion is the connecting parts of car, trunnion of Chang An automobile company is manufactured hammer forging. The fracture failure of bottom die happened in the process of service. On the serious working condition, its serving life is short. The working conditions of hammer forging die generally is on a huge impact, violent friction and the snap hot and cold. Failure form of hammer forging is die wear or plastic deformation or fracture. Through the long-term production practice is summarized, Wear, plastic deformation failure accounted for about 70%, fracture(crack) accounted for about 30%.This paper first studied the concave die macro fracture morphology, found that the fatigue fracture characteristics: At the same time corresponding to the mold cavity geometric structure characteristics, on the working process of the load and stress concentration is the produce of the main causes of fatigue fracture.Secondly, according to the trunnion of hammer forging production process, the finite element model is established, the finite element numerical simulation analysis. The results showed that the die deep groove fillet transition region of the stress concentration area, is dangerous place to die. Simulations verify the macro fracture observation inference.Then, in order to decrease the rounded place of stress concentration, reduce the rounded corners of the maximum stress value of a single point, and make the rounded at the stress value of easing, delayed fracture cracks produced and extended, which to a certain extent, improve the service life of forging die hammer. This paper adopts gradually increase the rounded corners need draft angle and radius method to change the mould structure, thus it is concluded that the optimization of the hammer forging die structure.Finally, ALOF software had carried on the simulation analysis of die fracture propagation, forecasted and analyzed the trend of crack growth. The application of this method which is for the study of crack formation and propagation provides an important reference.