Fatigue Life Analysis And Topology Structural Optimization On Stamping Die Of High Strength Steels

With the popularization of cars, the social problems caused by the automotive industry and related industries have become the focus of attention. To achieve the goal of sustainable development, automobile enterprises have launched the strategy of energy-saving and environmental protection, the main way is developing vigorously the cars with low fuel consumption and low emissions. High strength steel with high mechanical strength, good formability and mature manufacturing process has a wide range of applications in lightweight and improving strength of the car body, it has become the primary method to realize energy saving and emission reduction, but it also has brought new challenges for material selection and mould structure design.Compared to the traditional low strength steel, the forming force of high strength steel in stamping process is higher, with perennial cyclic loading of high stress and high impact, stamping die is prone to wear, tear and fatigue failure. In order to avoid fatigue phenomenon, a lot of mould enterprises has improved the fatigue life by increasing safety factor of mold, which often result in higher production costs, but the mould performance did not improve. Therefore, it is of important to research fatigue life and structural optimization of stamping die of high strength steel.In this paper, the punch most severed in the stamping die of high strength steel was the researching object, the fatigue properties of topological structure of punch were analysed by the analysis of structure stress, fatigue life prediction and structural topology optimization. Through the finite analysis results of structure force, we knew that the equivalent stress distribution of punch is nonuniform at different times in stamping process, the majority of equivalent stress concentrated in the corner and ups where the convex and concave feature are relatively obvious, these dangerous position was also prone to fatigue damage. The maximum stress position was selected as the object for fatigue analysis, it was known that the theory life of punch is far greater than the design life, so the punch structure has optimization space. Then punch structure was better by using the topology optimization technology to optimize the structure design of the die.Through a series of analysis and optimization, punch quality with new design decreased more than 20%, structure stress analysis and fatigue life estimation were completed, in the whole stamping process, although the average value of maximum equivalent stress of punch increased slightly, but the integral level was same compared with the integral level before optimization. At the same time, the peak of punch stress is reduced so that the fatigue life increased.Based on the above research results, the optimize design method of punch structure and design standard of key parameters for small high strength steel stamping die were proposed, which provided a reference basis for the design and development of stamping die of high strength steel.