6533b827fe1ef96bd12866d0

RESEARCH PRODUCT

Process parameters calibration in 3D tube hydroforming processes

subject

description

In tube hydroforming the concurrent actions of pressurized fluid and mechanical feeding allow to obtain tube shapes characterized by complex geometries such as different diameters sections and/or bulged zones. What is crucial in such processes is the proper design of operative parameters aimed to avoid defects (for instance shape defects or ductile fractures). The main process parameters are material feeding history (i.e. the punches velocity history) and internal pressure path during the process. In more complex three dimensional processes, also the action of a counterpunch is generally useful to reduce thinning in particular in expansion zones of the tube (i.e. T or Y shaped tubes). The good calibration of these parameters allows the optimal design of the process; in fact many researches have proposed different approaches to the optimization of these parameters. Generally, the main goals in the optimization approaches concern the control of thinning and the reaching of the desired final shape. In this paper, a fully three dimensional tube hydroforming operation is studied, aimed to produce a T‐shaped tube. A numerical simulations campaign was developed in order to analyze the influence of process parameters on the final product quality; in particular, the influence of the pressure path was considered in order to evaluate the effects of wrinkling phenomenon on thickness distribution. The basic idea is that the possibility to determine useful wrinkles at an early stage of the process may lead to better results in terms of maximum thinning on the final part. The numerical investigations led to a knowledge base about the process mechanics and the influence of wrinkling behavior which is very effective in order to implement an optimization procedure on the process parameters.