Optimal design of hydroforming of pure titanium elbow with small bending radius based on response surface method

DOI:	10.11809/bqzbgcxb2024.10.016
Keywords:	small bend radius; hydroforming; optimization of response surface method;finite element analysis
Abstract:	In order to solve the defects of wrinkling and excessive thinning in the forming of titanium elbow with small bending radius, this paper used hydroforming to form TA2 pure titanium elbow with diameter of Φ69 mm×1 mm and bending radius of 65 mm. In order to obtain the best process parameters of elbows with small bend radius in the process of hydraulic bending, the finite element simulation analysis of elbows with small bend radius was carried out by finite element simulation method. Firstly, the influence of internal pressure and unilateral feeding amount before forming on the forming effect of elbows with small bend radius is studied. Then, combined with the response surface method, the scheme is designed by Central Composite Design (CCD) method, and an effective response surface model is established. In the forming process, the internal pressure before forming, unilateral feeding amount and friction coefficient are taken as design variables, and the thickness reduction and thickening after elbows with small bend radius forming are taken as response. The results show that in a certain range, the formability of elbows with small bend radius can be effectively improved by using higher internal pressure and higher unilateral feeding amount. The response surface optimization results show that when the internal pressure is 12.164 MPa, the unilateral feeding amount is 7 mm and the friction coefficient is less than 0.2, the thinning of the parts can be controlled at 15.7% and the thickening at 4.792%. The experimental results show that the actual thinning rate is 15% and the thickening rate is 5.7%. The experimental results are compared well with the numerical simulation, and there are no obvious defects. The accuracy of the response surface model is verified, and the best hydraulic bending process path is obtained.
Issue:	Vol. 45 No. 10 (2024)
Published:	2024-10-31
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