Research On The Application Of Hot-forming Technology Of High Strength Steel In Auto-body Structure

The weight of car body contributes 40% of the whole,so the lightweight of car body play an important role in the development of lightweight vehicles, using high strength steel is one of the most important methods to achieve the lightweight of auto-body. High strength steel can meet the strength requirements and effectively reduce the numbers and the thickness of the sheet; the other hand, high strength steel can make the body more easily meet safety performance. Howeve,with the enhancement of the steel strength,its formability is worsened drarnaticall.So, failure and fracture are always occurred stamping. As a new production process,hot stamping can help to solve these problems. Hot stamping is a technics that make part shape up in the hot stamping die by using metal's characteristic that plasticity and tractility increase rapidly and yield stress decrease rapidly. The material has better plasticity,higher forming limit and easier to shape in hot stamping than in cold stamping. At present, thermal forming technology has been widely used in the world's automotive companies, has mostly used in parts which require high collision performance.The side-door impact beam as one of important auto-body structure parts, in the event of side collision, could greatly reduce deformation of the side door, which can reduce vehicle impact damage to the vehicle occupants,so the beam must ensure high strength. As the opening and closing pieces, the door can not be too heavy, the weight of side door beam should also be controlled, in order to meet lightweight and impact these two requirements, hot-formed steel is an ideal choice. In addition, the material strength and hardness will be greatly improved after quenching cooling for steel.Have studied the side beam blank design in the near net shape technology for the difficulties to follow-up process based on this issue.This paper's research studies on a side-door impact beam.At first,by analyzing the fundamental of hot stamping, effective engineering-use hot stamping flow has been instituted in this paper. Have studied the impact beam blanks shape design using near net shape technique, effectively reduced the processing costs caused by hot stamping. Some key numerical simulation technologies based on the PAMSTAMP2G have been studied in this paper. Have designed the hot stamping die by analyzing the shape and figuration characteristic of the object part. Have founded the mechanics and finite element model of steel hot stamping. By simulating the whole hot stamping process, have found the influence of blank holder force,friction coefficient in simulation of hot stamping,correlative parts' stress,strain and temperature distribution have been found. Have resolved the choice problem of some key parameters such as contact conductance related to pressure and part-die contact heat transfer coefficient in the thermal-stress coupled analysis. Have studied collision performance of the hot stamping impact beam, the beam can guarantee safety and the weight can be reduced by 30% compared to useing ordinary steel plate.