Numerical Simulation And Parameters Optimization Of Flexible Rolling Process For Three-dimensional Surface

Flexible rolling forming is a novel technology of continuous forming for three-demensional surface parts,combining multi-point adjusting method and rolling technology.The process employs two flexible rolls as forming tool,and depends on the uniform distribution of flexible roll gap and the rotation of the flexible rolls to realize dieless,continuous and efficient forming for three-dimensional surface parts.Flexible rolling forming has the advantages with lower cost,flexible forming and wider range of shaping,etc.Thus,it's easy to meet much industry demand for individual surface sheet parts and has broad application prospect in aerospace,ships,civilian industry,etc.In order to improve flexible rolling forming process,in this paper,the theory of flexible rolling forming process is analyzed and the law of forming parameters is explored by numerical simulation and experimental research,the optimization experimental design of the flexible roll adjusting radius,the maximum thinning rate and the plate thickness is carried out,which provides the optimization to flexible rolling process.The main contents of this paper are as follows:(1)Principle of flexible rolling forming process is analyzed through plastic mechanics,geometry and plate deformation.Forming characteristics of convex surface and saddle parts are analyzed.Based on the theory of plastic forming,the forming process and the longitudinal bending deformation are analyzed.Based on the practical test device whose upper and lower rolls can only be bent with small deflection,the roll gap control function is established.(2)The finite element model of flexible rolling forming is established.The shape of two typical three-dimensional parts is analyzed in transverse,longitudinal and thickness directions.It can be concluded that the forming parts have good consistency and verified that the roll gap design is valid and the finite element model is reasonable.The influence of different parameters on the forming results of saddle parts is analyzed by numerical simulation.The results show that with the increase of flexible roll adjusting radii,transverse and longitudinal curvature decreases;with the increase of maximum thinning rates,transverse curvature decreases,longitudinal curvature increases;with the increase of plate thickness,transverse curvature increases,longitudinal curvature decreases.(3)On the basis of numerical simulation,flexible roll adjusting radius,maximum thinning rate and plate thickness are further optimized through orthogonal experimental design,experimental data employs range and variance to analysis the primary and secondary relationship for the process parameters.The significance level and contribution rate of different process parameters are compared.The orthogonal experiment is used to quantify the contribution of the process parameters for the forming result,which makes significance level more intuitive.And the interaction between transverse and longitudinal deformation factors is verified.Finally,the optimal combination of process parameters is obtained.(4)Experimental verification for the theory and numerical simulation of the flexible rolling forming is carried out.The experimental results show that the convex parts and saddle parts are in good forming consistency.The experiments are carried out to study the flexible rolling forming process with different parameters,and the forming parts shape is analyzed.The experimental results are basically consistent with the simulation results.