Optimization of processing parameters for double-ridged rectangular tube rotary draw bending based on grey relational analysis

Abstract

The rotary draw bending of double-ridged rectangular tube is a complex nonlinear physical process with multifactors coupling effects. Processing parameters, especially clearances and friction coefficients between tube and various dies, have a significant effect on the forming quality of the double-ridged rectangular tube in rotary draw bending. If the values of these processing parameters are inappropriate, some defects including cross-sectional deformation, wall thinning, and wall thickening easily occur in the bending process of double-ridged rectangular tube. So optimization of these processing parameters is of great importance to control these defects. Based on the grey relational analysis method combined with the orthogonal experimental design and finite element simulation, a grey relational analysis model was established for the rotary draw bending process of double-ridged rectangular H96 brass tube. With the model, optimization of clearances and friction coefficients between tube and various dies was implemented with consideration of interactive effects of the above defects. The results show that (1) the main factors influencing cross-sectional deformation, wall thickening, and wall thinning are tube–mandrel clearance Δcm, tube-bending die clearance Δcb, and tube–mandrel clearance Δcm, respectively. (2) The optimal values of clearances Δcm, Δcp, Δcw, and Δcb and friction coefficients μm, μp, μw, and μb of tube–mandrel, tube–pressure die, tube–wiper die, and tube-bending die are 0.15, 0.2, 0.2, 0.2, 0.02, 0.3, 0.06 and 0.17 mm, respectively. Furthermore, the verification for the optimal values of these processing parameters was carried out, and the double-ridged rectangular H96 bent tube obtained by using the optimal values of these processing parameters has the minimum values of cross-sectional deformation, wall thinning, and wall thickening and can satisfy the national aviation industry standards.