| As one of the preferred materials in the design of automotive lightweight structure,the high strength steel sheet?HSS?provides strong guarantee for energy saving,environmental protection and sustainable development of automobile manufacturing industry,under the situation that low-carbon economy has become the significant goal in the whole world.However,compared with the ordinary low-carbon steel cold-rolled sheets,the forming ability become worse as the increase of yield strength,and the die/sheet interface is prone to galling as adhesion,scratches and scuffing,which affect the die's life of die and the part surface quality seriously.In the present work,the high strength steel sheet?SPFC590?is chosen as the forming material.Based on the process experiments and finite element method numerical simulation,the effects of different blank shape and blankholder force on the galling behavior are mainly investigated by square cup drawing process.The main results are obtained as follows:?1?The distribution of sticking behavior of concave model surface under different die heights is studied.The results show that as the height of the die increases,the interface slip distance increases,and the maximum line wear depth of the concave model surface increases.?2?The sticking mode distribution of the concave model surface of the regular quadrilateral,regular octagon and regular hexagonal blank shapes is studied.The results show that the distribution of the concave mold surface of the different shapes of the blank cup shape is similar,and it is concentrated at the junction of the rounded area and the straight wall area and the straight wall area is close to the exit of the concave mold.The degree of wear of the concave model surface is from regular to quadrilateral,positive sixteen deformation,and regular octagon.The elliptical blank shape is thus designed,and the wear of the concave mold surface is greatly improved,and the maximum line wear depth is 1.2×10-3mm.?3?The sticking mode distribution of concave model surface under different blank holder force control is studied.The results show that the concave mold surface sticking behavior is greatly improved when the blank holder force is controlled,and the maximum line wear depth is 2.0×10-3mmmm and 2.5×10-3mm respectively.The block blanking force control can appropriately improve the speed of the blank flowing into the die,and thus affect the sticking mode distribution of the concave model face.When the bending zone/transition zone/draw zone is in the order of 4 MPa/5 MPa/6MPa,the concave mold surface is small,and the maximum wire wear depth is1.0×10-3mm mm.?4?Three different die heights,three different blank shapes,and the presence or absence of blank holder force were designed to control the deep drawing of the cup below.The test results are consistent with the above simulation results,and the validity and rationality of the finite element simulation results are verified. |
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