Investigation into the factors that influence inverse bulging effect during sheet hydro-mechanical deep drawing

Lihui Lang,Jianmin Zhang,Yao Wang,Quanda Zhang,Kui Li,Shiyue Li,Y Qin,F Vollertsen,S J Yuan,J Lin,T A Dean

doi:10.1051/matecconf/20152106008

Abstract

The factors that influence inverse bulging effect during sheet hydro-mechanical deep drawing are especially researched in this paper. According to the different inverse bulging process, two modes can be singled: the initial inverse bulging (IIB) and the local inverse bulging (LIB). IIB includes two parameters: inverse bulging height ratio ( H Ib / t ) and inverse bulging pressure ratio ( P Ib / t ). LIB is influenced by IIB and has a direct relationship with liquid chamber pressure in the forming process. The optimal inverse bulging parameters of hemispherical bottom cylindrical part and flat bottom cylindrical part are obtained by numerical simulation. Process parameters including the clearance between the punch and the blank holder and the blank holder entrance radius that have a large influence on inverse bulging effect are optimized, so as to make inverse bulging effect behave better in hydroforming process. Finally, the accuracy of the numerical simulation results was verified by experiments.

Highlights

As one of the important processing technology in modern industry, sheet hydroforming has gained increasing interest in the aerospace and automotive manufacturing
local inverse bulging (LIB) is influenced by initial inverse bulging (IIB) and has a direct relationship with liquid chamber pressure in the forming process
Process parameters including the clearance between the punch and the blank holder and the blank holder entrance radius that have a large influence on inverse bulging effect are optimized, so as to make inverse bulging effect behave better in hydroforming process

Summary

Introduction

As one of the important processing technology in modern industry, sheet hydroforming has gained increasing interest in the aerospace and automotive manufacturing. Many parameters influence the process, such as the blank holding gap, the blank holding force, the die entrance radius, liquid chamber pressure and the inverse bulging effect [1,2,3,4,5]. In these parameters, the inverse bulging effect plays an important and decisive role in the sheet hydroforming. In order to avoid the influence of sheet thickness on inverse bulging effect and be consistent with other parameters research method, the inverse bulging height ratio HIb/t and the inverse bulging pressure ratio PIb/t are adopted to research inverse bulging effect in this paper [6]

Basic parameters

FEM model and scheme

Influence of inverse bulging effect on forming process

Influence of the blank holder entrance radius on inverse bulging

Experiment result and analysis

Conclusions