The study of forming concave-bottom cylindrical parts in hydroforming process

Abstract

Among the sheet-hydroforming techniques, hydrodynamic deep drawing assisted by radial pressure has introduced good results for forming parts with high drawing ratio. Forming concave-bottom cylindrical parts is complicated through conventional deep drawing and requires several steps. Hydroforming is one of the techniques that can resolve such problems. In this paper, forming of concave-bottom parts has been studied by using finite element simulation and experiment through hydrodynamic deep drawing assisted by radial pressure. The effects of pressure path and geometrical parameters of the punch on thickness distribution and punch force have also been investigated. The results illustrate that after forming the concave profile of the part, by increasing the maximum fluid pressure, the thickness of critical regions does not change. Thus, the pressure path with the lowest maximum pressure that can form the concave profile of the part is the best pressure path for forming a concave-bottom part. Meanwhile, increasing the concavity height and punch corner radius affects thickness reduction in critical regions, but these parameters do not have any significant effects on maximum punch force.