Studies on hydroformed tubular components

Abstract

The process of tube hydro-forming (THF) has gradually come into use over the last half decade for manufacturing aircraft and automobile components. In tubular hydro-forming process an internal fluid is used as the forming medium and the tube is bulged into the desired shape through simultaneous application of axial feed and internal pressure. Using the THF process, manufactures are able to produce parts of complex shape which are lighter and have fewer welds than those using alternative metal forming techniques. Due to the complex nature of the process, the best method to study the behaviour of the process is by using numerical techniques and advanced explicit finite element (FE) codes. A counter punch is usually used to control the protrusion height, to control the evolution of thickness and also to avoid over thinning in T-shape hydroforming. The details of Tube Hydroforming process with counter punch against protrusion are used to avoid the bursting failure. Trials of hydroforming of AA 6063 of thickness 1.77 mm have been carried out at room temperature with counter punch. The tubes were annealed prior to the tube forming. Operating parameters viz. internal pressure and axial feed were adjusted to obtain a successful product. Parameters must suited for realising defect free products have been recorded. Another set of trials have been carried out with reduced counter punch force and without counter punch. The realized product quality was not good as expected. The process was simulated using ABAQUS software. Holloman s model was used to simulate the material behaviour. The analysis results were compared with experimental values.The correlation of input parameters namely, tube wall thickness, tube length, loading time and coefficient of friction are correlated with protrusion height and percentage change in wall thickness.A mathematical correlation for these parameters are developed utilizing Box-Behnken response surface method. The required responses are acquired using a developed finite element model cons