A Numerical Study Of Springback Deformation Properties Of Die-less Spinning And Its Multi Roller Path Planning Method

Spinning is a kind of typical continuous local forming technology, which is widely used in the manufacturing of high quality and precision products, such as products in aviation, automobile and appliance industries because of its principle of chipless and high performance manufacturing. However, with the increasing need of individualization and medium and small batch products, conventional spinning can no longer fulfill these needs. Consequently, die-less spinning is proposed in these situations for the reasons that it eliminates the reliable of special mould in its processes and increases the flexibility and adaptability of the process. In this thesis, the springback properties and the roller path planning will be investigated, in order to reveal the free deformation mechanism of the die-less spinning process and to establish a theoretical base for future application in industries.Build analysis models for the forming process and springback process in die-less spinning by utilizing the finite element method and the related software (ansys/ls-dyna). The Explicit method is used for the simulation of forming process of die-less spinning, while the Implicit Method is used for the springback process, which is the basic research techniques for the later researches of deformation mechanism and springback properties of the die-less spinning.Tons of model data, such as forces, stress and strain data through lots of numerical experiments are obtained in order to realize the free deformation properties of the blank in die-less spinning. The stress circumstances in die-less spinning is similar with that of conventional spinning, however, they contribute to a more complicated phenomena. The reason is because of the free deformation of the blank, which could be controlled by adding a supplementary roller in theoretical. At the same time, the springback in die-less spinning is comprised with whole spingback which is similar with that in stamping process and local springback in the deformed area of the blank which is caused by the deforming force from the deforming area.The expressing method of complex curved surface products is studied with the help of geometrical mechanism and the control parameters (deflection angles) for the curved surface are obtaine as well. On basis of that, establish a group of numerical experiments according to the control parameters to get the relationship between the parameters and the springback amount of the blank, thus realizing the proper range of deflection angles and the effect model of deflection angle to springback property.Finally, by synthesizing the geometrical mechanism and the process properties of die-less spinning, we achieved a method to determine the pass numbers and the intermediate path curves in multi pass die-less spinning. To make the method more precise, we then applied into the springback effect model obtained before to revise the roller paths of each pass, fulfilling the effectively plan of multi roller paths in the end. The method is validated by a simulation experiment of die-less spinning of a cup. Meanwhile, the springback control effectiveness of supplementary roller in die-less spinning is also tested in the end, which is verified to be an effective way to assist the roller path planning method raised in this paper to optimize the springback phenomena in die-less spinning.