Numerical Simulation And Process Optimization Of Flexible Roll Forming Process

Flexible rolling is a new type of three-dimensional surface continuous forming process,combining the advantages of flexible forming of multi-point forming process and continuous forming of traditional rolling.In the forming process,a continuous three-dimensional curved surface is obtained by relying on the special uneven roll gap distribution between the upper and lower work rolls.The rotation of the flexible work rolls itself to achieve continuous feed of the sheet metal.Based on the analysis of flexible rolling forming(FRF)process principle,this paper explored the influence of sheet size on the effect of FRF by combining numerical simulation with experimental verification.The multi-pass forming process was used to improve the thickness reduction ability of the sheet metal in the flexible rolling.Finally,the purpose of optimizing the forming process has been achieved.The specific research content of this article and its conclusions are as follows:(1)The principle and process of FRF was analyzed through the geometry and mechanical properties of the formed parts.Based on the non-uniform plastic strain of the sheet metal,the characteristics of the deformed contact zone were summarized.Combined with the distribution characteristics of the forming rolls,the roll gap functions were established for the typical curved surface part,the convex curved surface part and the saddle shape part respectively.The numerical relationship between the processing parameters was determined.(2)Based on the principle of FRF,a discrete flexible rolls finite element model was established.Combining the basic knowledge of finite element,the reasonable setting of parameters such as mesh division and boundary conditions in the model was determined.From the aspects of stress strain and thickness thinning distribution,the numerical simulation results were analyzed to verify the rationality of the uneven distribution of roll gaps.The horizontal and vertical bending radii and contour lines of the forming part were extracted respectively,and the forming part was analyzed for surface error.The error distribution of each area of the forming part was discussed.(3)The FRF effect was analyzed from the distribution of forming zone and bending deformation.Combining with the numerical simulation results,the effect of the sheet metal size on the forming effect of the curved surface was studied from the aspects of the length,the width and the thickness of sheet metal.Under the same conditions,the ratio of the length of the stable zone of the sheet metal can be effectively increased by changing the size of the sheet metal.The utilization rate of the sheet metal can be improved.Thus,the unnecessary cutting can be reduced,and the processing cost can be reduced.(4)Taking the convex surface as an example,the influence of the distribution of the roll gap,the reduction amount and the thickness of the sheet metal on the thinning ability of the sheet thickness was discussed through finite element numerical simulation.Combined with the influence of roll gap distribution and reduction,a multi-pass forming process was introduced.The principle is that a large deformation is divided into multiple small deformations,and multiple deformations of small deformations finally achieve bending forming.The use of multi-pass forming process can significantly improve the flexible rolling forming effect.With the increase in the number of forming passes,the effect became more obvious.Finally,the purpose of optimizing the flexible rolling forming process was achieved.(5)The related FRF experiment was carried out and the reliability of numerical simulation was proved.The forming effect of different forming parts was analyzed.The influence rule of sheet metal size on forming effect was verified.The rationality of multi-pass forming process in FRF application was determined.