Design and Modeling Studies of Tube End Expansion using Response Surface Methodology

The production of various profiles on the ends of the tubes is referred as tube end forming process. In the present work, the elevated temperature forming studies have been performed. The thin walled tubes have been subjected to expansion process, and the process parameters namely the die angle, the die ratio and the operating temperatures that influence the expansion of tube ends at elevated temperatures is carried out. The range of operating parameters has been identified by performing simulation studies. The expansion parameters have been evaluated for AA2014 alloy for performing the simulation studies. Experimental matrix has been developed from the feasible range, got from the simulation results. Design of experiments is used for the optimization of process parameters. Response Surface Method's (RSM) and Box-Behenken design (BBD) is used for developing the mathematical model for expansion. Analysis of variance (ANOVA) is used to analyze the influence of process parameters on the expansion of tube ends. The effect of various process combinations of expansion are analyzed through graphical representations. The developed model is found to be appropriate, as the coefficient of determination value is very high and is equal to 0.9726. The predicted values are found to coincide well with the experimental results, within acceptable error limits.