The Lifetime Estimation Of Fine-blanking Male-die Based On FEM Analysis

Die stress is one of the main factors causing damage of fine-blanking dies. The mechanics of fatigue has not been studied deeply due to the complex processes in die stress alternation. Based on the detail reviews of the development of materials forming and dies stresses analysis used finite element method(FEM), in this work, the cold forming process of AISI-1010 billet is simulated by using the commercial finite element analysis package, DEFR0M-3D. For a comparison with the distribution or stress/strain in die, the stress field of fine-blanking pounch is simulated. The main results can be listed as followed:From consideration of the die as an elastic-plastic body, the FEM results are credible. It is showed that the finite element method used in die stresses analysis is feasible and effective. According to the results, the peak of equivalent-stress all appears in the corners area of the core die. Serious stress concentration and continuous cyclic high stress contribute to tipping and cracks.Because the Lame equation can't describe die stress accurately, it is impossible to get the optimization of the fine-blanking die design as based on this formula. By FEM, it is easy to obtain all the accurate mechanical information, such as die stress, strain, stress concentration, and effective stress etc. Obviously the FEM analysis is paramount and effective for the prediction of fatigue life and reduction of high stress within the tools. And it can save a lot of cost in experiment.In this thesis, a fatigue failure model for die life estimation was set up by using local stress-strain approach. Pre-estimate the fatigue life of die will find a new way for fine-blanking die design optimization.According to this estimation equation, the forming quality and life of die are different with the changes of technology parameter. Consideration of dimensional effect and stress gradient effect, index number of fatigue strength was amended. So the model could be appropriated for the estimation of low-cycle fatigue and high-cycle fatigue.Die stresses analysis using FEM and fatigue life model set up can help determine die quality and can give a good reference for dies development and manufacture.