Finite Element Simulation And Experiment On Internal Spinning For Thin-wall Shell With Ring Internal Rib

The thin shell with ring internal rib is a structure form widely used by curved generatrix shell, which is a preferred structure form in ensuring the stiffness and strength of parts under the condition of no weight reduction. The spinning of aluminium alloy thin-wall shell with internal strengthening belt was studied by the finite element simulation and experiment in this paper. Two kinds of inner spinning forming processes,which are spinning beginning at small end and spinning beginning at big end were presented and the microstructure and mechanical properties were analsized.The two kinds of spinning technologies of spinning beginning at small end and spinning beginning at big end were simulated by ABAQUS software. The spinning force and deformation conditions are calculated and analized. It can obtain thin-walled cylindrical shells with uniform deformation using the preliminary shape and the final forming process of spinning beginning at small end. The radial spinning load is the maximum value, axial spinning load is the secondary and the tangential spinning load is the minimum value. Compared with the radial spinning load, tangential spinning force can be neglected. The spinning load has a platform area during the spinning forming of the end frame and the middle skin section of the shell, where the forming process is stable.Axial travel of the spinning wheel is more big, the thinning rate and spinning load are greater in spinning end frame and middle skin part of the big end in shell, in which the maximum spinning load is appeared in this process. The expanding spinning can be implied if the big end is fixed, but the deformation instability zones will appear in the transition region of front frame and the skin section.The internal spinning forming laws of the spinning beginning at big end and the spinning beginning at small end are reserched by technology experiments for a thin shell with internal strengthening belt. There are two kinds of process when the curved generatrix thin-walled shell are formed by the process of spinning beginning at big end and spinning beginning at small end: one process is the wall thickness unchanged in size expansion, annother process is the wallthickness thinning in expanding indiameter.When the die’s half coneangle is less than the blank’s half coneangle, the thinning rates of the wall thickness in the process of spinning beginning at big end should be in accordance with the law of sine, but the process of spinning beginning at small end is not affected by the sine law. According to the results of orthogonal test, the internal spinning process parameters are displayed as following: the feed ratio is 0.6mm/r, the thinning rate is 25%,the fillet radius is 6mm and mounting angle is 25° of the spinning wheel.Through spinning test, the forming process of thin shell with internal strengthening belt which are spinning beginning at small end is the following: the blank cutting→the blank processing→the annealing treatment→the preliminary shaping→the quenching→the final forming →the parts machining. And the spinning process parameters corresponding to the above process is as follows: the maximum wall thickness reduction rate in the preform forming is 25% and the rate of the final forming is 10%, the fillet radius of spinning wheel is 6mm, the feed rate is 0.6 mm/r, teh spindle speed is 50 r/min, the thickness of the test has a ±0.05 mm difference and the circular degree is 0.15 mm.The microstructure and mechanical properties in skin section of a thin wall shell which is spinned were tested. The test results show that the sample’s grain size formed by the process of annealing and spinnign treatment is smaller and it is between 1μm~5μm.But the sample’s above strength does not meet the design requirements. Another grain size of the sample formed by is bigger and it is between 15μm~20μm. The larger the total deformation is,the smaller the grain size is. The tensile strength of this sample is greater than 360 MPa so it can comply with the design requirements. The fiber tissue can be produced in all the internal spinning test samples with tangential direction, the total deformation amount is larger, the more the tangential fibrous tissue obvious.Compared with the preliminary shape and the final forming with intermediate quenching process, the residual stress of product made by the process of annealing and spinnign treatment is smaller, the whole residual stresses of two Spinning process products is compressive stress.Through the finite element simulation and experimental research for spinning forming process of thin shell with ring internal rib, it is not only to determine the spinning forming process of an aluminium alloy thin shell and to provide the basis for thebatch production,but also to provide a reference to better solve the problem of the thin shell with ring internal rib spinning forming.