Temperature Field & Stress Field Simulation And Optimization Of Hot Forging Die

Hot Forging Die is an important processing equipment in Forging industry. It will bear cyclical thermal load and mechanical load in its working processing and these two loads will produce thermal stress and mechanical stress. Predecessors' research found the thermal stress which was produced by the variation of temperature field was the main cause of the failure and damage of the Hot Forging Die. In order to increase service life of Hot Forging Die, we have to resolve the problem of thermal stress.In this paper, I analyze the factors which influence the thermal stress on Hot Forging Die in theory first. I notice that these factors include craft parameter and physics parameter of material. Formers had made summary to the impact of physics parameter of Forging die materials to thermal stress. However, the influence of craft parameter (include preheat temperature, working beat, stayed time of forging and so on) to the temperature field and stress field did not win enough attention.In this paper, we regard the hub Hot Forging Die of car as prototype, regard DEFORM-2D program as tool, and simulate the work course of Hot Forging Die in different craft parameter. Finally, we get the stress field and temperature field when forging die work in succession under different craft parameter. We define temperature field when die works in thermal balance as temperature field of working in succession. The heat absorbed in one working cycle equals to heat that die distribute to the environment in the same cycle when forging die works under thermal balance. After analyzing the temperature field of working in succession, we divide the forging die into fluctuating and gradient area of temperature. The real working course proves that the fluctuating area which takes only a little part of die is the main district of damage of Hot Forging Die.We analyze the temperature field under different craft parameter and find that:â‘ The higher preheat temperature is, the easier to reach the balance state . The higher preheat temperature is, the higher temperature field of working in succession is. However, the temperature of working in succession is smaller than that of preheat temperature.â‘¡Working beat is changed by changing the time of different forging stage. And we find that it need less times of working circle to reach thermal balance if the working beat is slow. The range of temperature fluctuation is sharp with slow working beat. The change of temperature field of working in succession is irregular.â‘¢The longer the stayed time is, the faster the rising of temperature is. It will need less working circles to reach thermal balance with longer stayed time. Also, if the stayed time is long, the temperature field in working succession is high.After we simulate and analyze the stress field, we find that integrated equivalent stress is high at the shoulder of bottom die and the stress value of danger point reaches 2000 MPa. When the stroke of top die is 11mm, the stress of danger point will rise rapidly and reaches its extreme value finally.At the last of this paper, we optimize the bridge size of fash slot of this hub forging die. We find that we could get qualified product if we decrease the width of bridge size of fash slot from 10mm to 7mm. If this size is small, integrated equivalent stress of this forging die and forging force will diminish too. So we could decrease the width of bridge size of fash slot to 7mm.We not only find out craft parameters which can help alleviating thermal stress, but also provide a basis to design the functionally gradient materials(FGM). We believe it will help improving service life of Hot Forging Die a lot.