Effect Of Lubrication On The Dual-phase Steel DP500 In Deep Drawing Process

In recent years, major objectives of the world's automotive industry are saving energy, preventing environmental degradation and improving vehicle safety. Reducing vehicle weight to reduce energy consumption and greenhouse gas emissions, so improving vehicle fuel economy as an important means is taken by the auto manufacturers to improve product competitiveness in auto-markets. High strength steel, ultrahigh strength steel and advanced high strength steel in the weight loss achieve a good result and get a good application, and the proportion of using in the car body is also increased every year.Firstly, sheet metal friction mechanical analysis is carried out to obtain the friction variation in deep-drawing process in this article. Dynaform5.5—Sheet metal forming special software is used to build up a model for the DP500 high-strength steel sheet on the thickness of 0.8mm for the finite element analysis to study the impact of the parameter of friction, which is between sheet and die, on FLD in round cup deep-drawing. The results show that the conditions of friction can change the FLD in the round cup forming of the DP500. At the same time, the impact of lubrication (between the sheet and the die) on thickness is studied. Improved lubrication condition can improve the round cup wall thickness is given out. The process window (limit drawing ratio) can be increased by lower friction. Springback of DP500 is studied too, the results show that springback curvature at different positions on the sensitivity of different coefficient of friction, and interaction of each other is serious.Secondly, adopting a common version of ABAQUS 6.8 finite element analysis software, the DP500 sheet metal forming process is simulated. By extracting contact surface force between the sheet and different die in the round cup deep-drawing to evaluate the friction between them. The contacts surface forces of the sheet and die in the direction of the deep-drawing is used to compare the different coefficients of friction in the phase of unloading process. Improving the lubrication conditions, the various contact surface contacts in the deep-drawing direction make the value of return time T shorter. It is founded that the contacts force in Y in the unload process can be used as the merits of the standard to evaluation the different kinds of lubricants.Finally, using different lubricants-PTFE film, chlorinated paraffin oil and dry friction, the sheet of ST14 and DP500 steel are compared with experimental studies in the deep-drawing process. The experimental results show that in the same die size and blank holder force conditions, with the improvement of lubrication conditions, round cup parts limit forming height is increased, the thickness distribution became uniform too. It shows that improving the lubrication of high strength steel DP500 in this experiment conditions can improve the forming properties, and is same as the law of the finite element simulation results basically.