Research On Hydroforming Technology Of Aluminum Alloy Coverring

With the increasingly stringent fuel consumption and emission indicators,automobile factories continue to pursue lightweight body.Hydraulic forming is an important way to realize it.It has great advantages in deep drawing of aluminium alloy and complex tubular products.In addition,with the acceleration of automobile product renewal,the research and development cycle of the whole vehicle is shortening day by day.The CAE,CAD and orthogonal test method play an active role in shortening the product development cycle and reducing the quality risk of parts.This paper introduces the principle,advantages and disadvantages of active and passive hydroforming,and expounds its application scope,that is,active hydroforming is suitable for panel with gentle shape,but needs highly A surface thinning rate and higher A surface quality.The passive hydroforming die structure is easy to realize,and it is suitable for all inner panels and outer panels which need friction retention effect to improve formability,which have complex shape,large drawing depth and high requirement for surface quality of A surface.In this paper,three kinds of aluminium alloy cover panels,namely,outer plate of Hood,inner plate of Hood and Roof,were developed.Based on the characteristics of the three parts,different hydroforming processes were adopted.The forming defects are predicted by finite element simulation technology,and the optimum combination of process parameters is obtained by optimizing the blank holder force,hydraulic loading curve and drag coefficient of drawbead with orthogonal test method.After the finite element simulation confirms that the process design and technological parameters are reasonable and flawless,the die material is developed and verified.The results show that the finite element simulation technology and the orthogonal test method can effectively avoid the formability risk,and the difference between theory and material is small.Through on-site debugging,the qualified aluminium alloy panel is finally obtained,and its A-plane audit quality and thinning rate meet the requirements.This is of great significance for the development and reserve of lightweight technology.