Experiment And Finite Element Analysis On Fatigue Life Of Fine-blanking Die

Fine-blanking is a kind of no pared processing technology. The fine-blanking part is high quality and high precision. As the high efficiency , economic and low energy consumption, the fine blanking technology is the necessary choice to produce many key parts in industrial fields, such as auto industry etc. While, because of bad environment during fine-blanking process, especially the cutting edge of core plate and cavity plate, tesion, thermal effect and friction force is huge. That makes so much abrasion in the fine blanking die that the life of die is low. Those constraints restrict the further expansion of the application of fine-blanking technology. Therefore, it requires to research failure mechanism and fatigue life of the fine-blanking mould at great length.This article chooses the powder metallurgical steel called S970, a kind of fine-blanking mould material, as the object of fatigue test research. National standards are used in the tensile test and fatigue test for S790. On the basis of the experiments, it is going to take the fine-blanking mould of ratchet wheel parts as the object for finite element analysis, and simulate the fatigue numerical of the simplified fine-blanking mould models.Firstly, this paper discusses the fatigue-related theories, raises the basic principles and steps of the fatigue analysis, analyses damage and macro fracture's characteristics of fine-blanking mould. Finally, the result indicates the fine-blanking die fatigue belongs to high cycle fatigue, and holds a point of view that the nominal stress can better estimate the life of fine-blanking die.Secondly, samples of S790 steel tensile and fatigue test are prepared by machining and heat treatment. The tensile test proves that the tensile yield strength of S790 is 2564MPa, the ultimate tensile strength is 2955MPa. The fatigue test results that S790 steel is especially sensitive to nicks. It should pay much attention to defects of stress concentration, scratch etc. in parts'manufacturing.Based on the experiments and theoretical formulas, the static strength of the simplified TJB9 6804 ratchet wheel fine-blanking die models is simulated by ANSYS Workbench. And it obtains that the static strength of the main punch meets the requirement under the static load. Then, the whole simplified die models are simulated at the aspect of the fatigue performance. The consequence of the simulation shows that the minimum life lies in the main punch, and the value of life and damage location is close to practical situation.At last, this paper studies the effect factors of the fine-blanking die fatigue life, and validates these factors by simulation. This paper also raises several methods of improving the fatigue performance of the fine-blanking die.