Research On The Formability Of Ultra-high Strength Steel Part For Structure And Stamping Process Design

With the development of the automobile industry and people's increasing emphasis on energy saving and environmental protection,the current automobile manufacturing industry also meets the requirements of energy saving and environmental protection as much as possible while ensuring the safety performance of automobiles.Lightweight of automobiles can effectively save automobile fuel consumption and reduce exhaust emissions,which has become an important trend of current automobile technology development.The emergence of ultra-high strength steel and its application in automobile body parts can effectively ensure the safety of automobiles while also contributing to the goal of the weight reduction of automobile bodies.However,due to the high strength and low elongation of ultra-high strength steel,it is very difficult to process and form,and it is very prone to defects such as cracking and wrinkling.The research on the performance of ultra-high strength steel is the current research focus of material technology.Many scholars have conducted many related researches on the formability of ultra-high strength steel.However,there are few studies on the application of ultra-high strength steel parts,and the research on the structure itself and stamping process of the ultra-high strength steel parts at the same time is even less,which is not conducive to the widespread application of ultra-high strength steel.Therefore,from the perspective of the application of ultra-high strength steel parts,this article studied the formability of automotive ultra-high trength steel structural parts for structure and stamping process design.And it is of great significance for guiding the structural design and stamping process design of parts in the production process and promoting the wide application of ultra-high strength steel.Through analysis and summary,it has accumulated some experience for the structural design and manufacturing of ultra-high strength steel automobile body parts.In this paper,an ultra-high strength steel B-pillar reinforcement plate was taken as the research object,and the stamping simulation analysis and multi-objective optimization were also carried out.The maximum thinning rate and maximum wrinkle factor were selected as the evaluation indicators of formability.Considering the structural parameters of the parts and the stamping process parameters comprehensively,three structural parameters of upper bending radius,lower bending radius,elevation tilt angle and two process parameters of blank holder force and drawbead coefficient are used as optimization parameters.The experimental design was carried out and the Kriging approximate model was constructed.Based on the constructed approximate model and according to the multi-objective optimization theory,the NASG-II algorithm was used to perform multi-objective optimization design on the relevant parameters that affect the formability of ultra-high strength steel parts.The optimal parameters combination obtained is R=14mm,r=15mm,?=17°,F=530k N and ?=0.11.The part structure and stamping process were modified according to the optimized parameters combination.And it is verified through experiments that the optimized part has good formability.The risk of cracking and wrinkling defects is greatly reduced.