Research On Apparatus Parameters Of Strip Metal In-Plane Bending Under Unequal Compression

In-plane bending of strip metal under unequal compressing, achieving the bending by using of the unequal plastic deformation, can be developed into an advanced precision plastic forming technology. The key parametric effect and optimization of apparatus parameters related directly to the forming, has become an important subject in the research and development of the process. Therefore, in this dissertation, from based on force-energy parameters wrinkling, and bending radius, a systematical investigation has been carried out by using FEM numerical simulation combined with theoretical analysis and experiment. A brief introduction to the project and its main achievements obtained are as follows:A new algorithm for obtaining the rolling moment has been established. It is shown that the new algorithm is reliable by comparison of the results from rigid-plastic FEM numerical simulation system IBS with experimental results.The effect of cone-apex angle and rotating speed of conical rollers on force-energy parameters has been revealed by using IBS system in conjunction with the algorithm, and the result indicates that the total rolling force, the rolling moment, and the average rolling force firstly decrease and then increase with an increase of cone-apex angle, and reach the minimum when the cone-apex angle is 60°; The effect of the rotating speed on the total rolling force, the average rolling force and the rolling moment is similar to approximate wave variation in general, but with slight margin, and they reach to the minimum when the rotating speed is 40r/p.m.The relationship of the cone-apex angle and the rotating speed of conical rollers with the stability of forming process has been studied by IBS system, and the result shows that the process firstly produces the stable forming and then produces the internal wrinkling with an increase of cone-apex angle. The relative compression width is the most important factor influencing the wrinkling, the relative compression thickness, the strength coefficient and the strain-hardening exponent are second factors; the cone-apex angle has a little effect on the wrinkling; and the effect of the rotating speed can be ignored.The forming limit of the process is the basis for optimization design and precision control of the process and its apparatus parameters. The used concept of forming limit of in-plane bending of strip metal under unequal compression has been corrected. A method for quantitatively determining the forming limit is put forward based on the unified criterion for predicting the internal and external wrinkling and by using numerical simulation system IBS, and its reliability has been validated by the experiment.The orthogonal numerical simulation has been carried out by using numerical simulation system IBS. The results show that the loading wedge angle is the most important factor influencing the minimum bending radius, the compression thickness is second factor, and then is the cone-apex angle and the rotating speed of conical rollers. The process reaches to the optimization when the cone-apex angle is 60° and the rotating speed is 40r/p.m.The achievements of this study lay a foundation for developing the forming apparatus, and are important to developing advanced forming technology of in-plane bending of strip metal.