Novel combined standard hydromechanical sheet hydroforming process

Abstract

Sheet hydroforming techniques are widely used in industries for the production of different components with specific characteristics. Despite the advantages of the conventional sheet hydroforming techniques, they have their own limitations. In this paper, to increase the application and to overcome the limitations of conventional deep drawing, a new sheet hydroforming technique is proposed that is a combination of the standard and the hydromechanical sheet hydroforming processes. The proposed method has the advantages of conventional processes but eliminates their limitations. This technique is used in forming a cylindrical cup and a complex industrial part. After applying the appropriate pressure path, the products are formed successfully in one stage without any defects. It is also shown that the required forming pressure in the proposed process is low compared with other sheet hydroforming processes. It is demonstrated that because of the low internal pressure required in the present method, pre-bulging does not have any significant effect on the thickness distribution of the product. It is concluded that in this process increasing the friction coefficient between punch and blank can reduce the sheet thinning.